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Title:
CENTERLESS BALL ELEMENT MACHINING SYSTEM, MACHINING WHEEL THEREFOR, AND METHOD OF MAKING AND USING THE SAME
Document Type and Number:
WIPO Patent Application WO/2021/030746
Kind Code:
A1
Abstract:
A centerless ball element machining system comprises a rotatable upper wheel comprising an upper base and a upper ball raceway, the upper wheel configured to be rotatably disposed on the upper wheel axis, the upper ball raceway comprising an upper abrasive material or an upper non-abrasive material and configured to contain a lubricant/abrasive media while the upper wheel is rotated; a rotatable lower wheel comprising a lower base and a lower ball raceway comprising a lower abrasive material or a lower non-abrasive material and configured to contain the lubricant/abrasive media while the lower wheel is rotated, the upper raceway profile disposed above and facing the lower raceway profile; and a bias member, the bias member operatively coupled to at least one of the upper wheel or the lower wheel and configured to provide a predetermined load on the ball element precursor from the upper wheel and the lower wheel.

Inventors:
CISLO LAWRENCE E (US)
Application Number:
PCT/US2020/046500
Publication Date:
February 18, 2021
Filing Date:
August 14, 2020
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
CISLO LAWRENCE E (US)
International Classes:
B21D53/00; B21H1/14; B21K1/02; B23B25/00; B23P17/00
Foreign References:
GB1359738A1974-07-10
US20080171492A12008-07-17
US6053804A2000-04-25
US20120180317A12012-07-19
US2964886A1960-12-20
US2332133A1943-10-19
Attorney, Agent or Firm:
ANDERSON, Edmund (US)
Download PDF:
Claims:
CLAIMS

What is claimed is:

1. A centerless ball element machining system, comprising: a rotatable upper machining wheel comprising a cylindrical upper base and a cylindrical upper ball raceway, the cylindrical upper base comprising an upper wheel axis, the cylindrical upper ball raceway comprising a circumferentially-extending concave upper raceway profile on an inner surface, the upper raceway profile configured to receive a ball element precursor comprising a ball element precursor material, the upper machining wheel configured to be rotatably disposed on the upper wheel axis, the cylindrical upper ball raceway comprising an upper abrasive material or an upper non-abrasive material and configured to contain a lubricant or an abrasive media while the upper machining wheel is rotated; a rotatable lower machining wheel comprising a cylindrical lower base and a cylindrical lower ball raceway, the cylindrical lower base comprising a lower wheel axis, the cylindrical lower ball raceway comprising a circumferentially-extending concave lower raceway profile on an inner surface, the lower raceway profile configured to receive the ball element precursor comprising the ball element material, the lower machining wheel configured to be rotatably disposed on the lower wheel axis, the cylindrical lower ball raceway comprising a lower abrasive material or a lower non-abrasive material and configured to contain the lubricant or the abrasive media while the lower machining wheel is rotated, the upper raceway profile disposed above the lower raceway profile with the upper raceway profile facing the lower raceway profile, the upper wheel axis spaced apart from the lower wheel axis by a predetermined distance selected to capture the ball element precursor between the upper raceway profile and the lower raceway profile; and a bias member, the bias member operatively coupled to at least one of the upper machining wheel or the lower machining wheel and configured to provide a predetermined load on the ball element precursor from the upper machining wheel and the lower machining wheel, the upper machining wheel and lower machining wheel configured to remove the ball element material from the ball element precursor upon rotation about the upper wheel axis and lower wheel axis, respectively, in the presence of the abrasive media, the upper raceway profile and lower raceway profile selected to increase the sphericity of the ball element precursor upon removal of the ball element material.

2. The centerless ball element machining system of claim 1, wherein the upper machining wheel comprises a plurality circumferentially-extending slots that are configured to pass through the ball element precursor for placement between the upper raceway profile and the lower raceway profile.

3. The centerless ball element machining system of claim 1, wherein the upper raceway profile comprises an upper elliptical shape, and wherein the lower raceway profile comprises a lower elliptical shape.

4. The centerless ball element machining system of claim 1, further comprising a drive assembly, the drive assembly operably coupled to and configured to rotate the upper machining wheel and the lower machining wheel.

5. The centerless ball element machining system of claim 4, wherein the drive assembly comprises an epicyclic gear set and an electric motor comprising a motor shaft configured for selectively controllable rotation about a motor axis that is rotatably and operably coupled to the epicyclic gear set.

6. The centerless ball element machining system of claim 5, wherein the epicyclic gear set comprises a ring gear configured for attachment to a gear table proximate a gear opening, an upper wheel planetary gear configured for selective attachment to and detachment from the upper machining wheel and configured for toothed engagement within the ring gear and rotation about the upper wheel axis, a lower wheel planetary gear configured for selective attachment to and detachment from the lower machining wheel and configured for toothed engagement within the ring gear and rotation about the lower wheel axis, the upper wheel planetary gear spaced apart from the lower wheel planetary gear.

7. The centerless ball element machining system of claim 6, further comprising a carrier assembly comprising: a lower carrier plate comprising a lower hub , a plurality of outwardly extending, radially spaced lower spokes attached to the lower hub and extending to a circumferential lower rim and defining a plurality of radially spaced, circumferentially-extending lower slots disposed therebetween, the lower hub configured for attachment to the motor shaft and comprising a downwardly extending, upwardly opening clutch pocket configured to receive a selectively and variably engageable/disengageable clutch and a torsion spring that are configured to be disposed on the motor shaft within the clutch pocket, the lower carrier plate comprising a lower gear shaft attached thereto and configured to receive a lower gear bearing that is configured for attachment to and rotatable disposition between the lower gear shaft and the lower planetary gear, the lower carrier plate configured for rotatable engagement with the ring gear; and an upper carrier plate comprising an upper hub , a plurality of outwardly extending, radially spaced upper spokes attached to the upper hub and extending to a circumferential upper rim and defining a plurality of radially spaced, circumferentially-extending upper slots disposed therebetween, the upper hub comprising a shaft portion configured for insertion into and locking torque transfer engagement with the torsion spring, the upper carrier plate comprising an upper gear shaft attached thereto and configured to receive an upper gear bearing that is configured for attachment to and rotatable disposition between the upper gear shaft and the upper wheel planetary gear, the upper gear shaft configured to extend through one of the circumferentially-extending upper slots, the upper carrier plate configured for rotatable engagement with the ring gear.

8. The centerless ball element machining system of claim 7, wherein the carrier assembly further comprises: an upper carrier bearing configured for disposition proximate the ring gear and a peripheral edge of the upper carrier plate and comprising an upper inner bearing race and an upper outer bearing race, the upper inner bearing race configured for pressed engagement onto an outer circumference of the ring gear, the upper outer bearing race configured for attachment to the upper carrier plate, the upper carrier bearing providing rotatable engagement of the upper carrier and the ring gear; and an lower carrier bearing configured for disposition proximate the upper carrier bearing and a peripheral edge of the lower carrier plate and comprising a lower inner bearing race and a lower outer bearing race, the lower inner bearing race configured for attachment to the lower carrier plate, the lower outer bearing race configured for attachment to the upper carrier plate and the upper outer bearing, the lower carrier bearing providing rotatable engagement of the lower carrier and the upper carrier bearing.

9. The centerless ball element machining system of claim 7, wherein the selectively and variably engageable/disengageable clutch and a torsion spring comprise the bias member, and wherein upon rotation of the motor and engagement of the clutch, a torque is applied to the torsion spring causing the torsion spring to wind up according to a predetermined spring rate and apply the predetermined load on the ball element precursor from the upper machining wheel and the lower machining wheel.

10. The centerless ball element machining system of claim 1, wherein the upper abrasive material and/or the lower abrasive material comprise diamond, boron carbide (B4C), silicon carbide (SiC), boron nitride (BN (e.g. cubic BN)), carbon-boron nitride (CBN), aluminum oxide (AI2O3), chromium oxide (CNCh), zirconium oxide, (ZrC^), silicon oxide (Si02), cerium oxide (CeCh), iron oxide (FeiCb), yttrium oxide (Y2O3), copper oxide (CuO), molybdenum oxide (M02O3), or tungsten carbide (WC), or a combination thereof, or a composite thereof.

11. The centerless ball element machining system of claim 1, wherein the abrasive media comprises a plurality of abrasive particles dispersed in a liquid medium.

12. The centerless ball element machining system of claim 11, wherein the abrasive particles comprise diamond, boron carbide (B4C), silicon carbide (SiC), boron nitride (BN (e.g. cubic BN)), carbon-boron nitride (CBN), aluminum oxide (AI2O3), chromium oxide (CnC ), zirconium oxide, (ZrCh), silicon oxide (Si02), cerium oxide (CeCh), iron oxide (Fe203), yttrium oxide (Y2O3), copper oxide (CuO), molybdenum oxide (M02O3), or tungsten carbide (WC), or a combination thereof, or a composite thereof.

13. The centerless ball element machining system of claim 1, further comprising a stop member that is configured to limit a translation of the upper wheel axis and the upper machining wheel as the ball element material is removed during machining of the ball element precursor.

14. The centerless ball element machining system of claim 1, wherein the upper machining wheel comprises a plurality of concentric cylindrical upper ball raceways comprising a plurality of concentric circumferentially-extending concave upper raceway profiles on respective inner surfaces, the upper raceway profiles configured to receive a corresponding plurality of the ball element precursors, and wherein the lower machining wheel comprises a plurality of concentric cylindrical lower ball raceways comprising a plurality of concentric circumferentially-extending concave lower raceway profiles on respective inner surfaces, the lower raceway profiles configured to receive the corresponding plurality of the ball element precursors.

15. The centerless ball element machining system of claim 1, wherein the upper machining wheel comprises a plurality of concentric upper machining wheels stacked on one another and configured to rotate together, and the lower machining wheel comprises a corresponding plurality of concentric lower machining wheels stacked on one another, the plurality of corresponding plurality of upper raceway profiles and plurality lower raceway profiles configured to receive a corresponding plurality of the ball element precursors.

16. The centerless ball element machining system of claim 1, wherein the upper machining wheel comprises a single upper machining wheel that is configured to be rotatably disposed on an upper wheel axis, and the lower machining wheel comprises a plurality of radially and circumferentially spaced lower machining wheels that are configured to be rotatably disposed on a corresponding plurality of lower axes, the upper raceway profile and plurality of lower raceway profiles configured to receive a corresponding plurality of the ball element precursors.

17. A centerless ball element machining wheel, comprising: a cylindrical base and a cylindrical ball raceway, the cylindrical base comprising a wheel axis, the cylindrical raceway comprising a circumferentially-extending concave raceway profile on an inner surface, the raceway profile configured to receive a ball element precursor comprising a ball element precursor material, the machining wheel configured to be rotatably disposed on the wheel axis, the cylindrical ball raceway comprising an abrasive material and/or a non-abrasive material configured to contain an abrasive media while the machining wheel is rotated.

18. The centerless ball machining wheel of claim 17, wherein the cylindrical ball raceway is selectively attachable and detachable and is configured for periodic removal and replacement.

19. The centerless ball machining wheel of claim 17, wherein the upper machining wheel comprises a plurality of concentric cylindrical upper ball raceways comprising a plurality of concentric circumferentially-extending concave upper raceway profiles on the upper inner surface, the upper raceway profiles configured to receive a corresponding plurality of the ball element precursors, and wherein the lower machining wheel comprises a plurality of concentric cylindrical lower ball raceways comprising a plurality of concentric circumferentially-extending concave lower raceway profiles on the lower inner surface, the lower raceway profiles configured to receive the corresponding plurality of the ball element precursors.

20. The centerless ball element machining wheel of claim 17, wherein the base comprises a metal, ceramic, engineering plastic, or a combination thereof.

21. The centerless ball element machining wheel of claim 17, wherein the upper abrasive material and/or the lower abrasive material comprise a diamond, boron carbide, silicon carbide, aluminum oxide, chromium oxide, zirconium oxide, silicon oxide, cerium oxide, iron oxide, yttrium oxide, copper oxide, molybdenum oxide, or carbon boron nitride, or a combination or composite thereof.

22. The centerless ball element machining wheel of claim 17, wherein the abrasive media comprises a plurality of abrasive particles dispersed in a liquid medium.

23. The centerless ball element machining wheel of claim 22, wherein the abrasive particles comprise diamond, boron carbide, silicon carbide, aluminum oxide, chromium oxide, zirconium oxide, silicon oxide, cerium oxide, iron oxide, yttrium oxide, copper oxide, or molybdenum oxide, and the liquid medium comprises water, a water soluble liquid, an oil, or a paste.

24. The centerless ball element machining wheel of claim 17, wherein ball element precursor material comprises a ceramic.

25. The centerless ball element machining wheel of claim 24, wherein the ceramic comprises silicon nitride.

26. A method of making a centerless ball element machining system, comprising: forming an upper machining wheel comprising a cylindrical upper base and a cylindrical upper ball raceway, the cylindrical upper base comprising an upper wheel axis, the cylindrical upper ball raceway comprising a circumferentially-extending concave upper raceway profile on an inner surface, the upper raceway profile configured to receive a ball element precursor comprising a ball element material, the upper machining wheel configured to be rotatably disposed on the upper wheel axis, the cylindrical upper ball raceway comprising an upper abrasive material and/or comprising a non-abrasive material and configured to contain an abrasive media while the upper machining wheel is rotated; a lower machining wheel comprising a cylindrical lower base and a cylindrical lower ball raceway, the cylindrical lower base comprising a lower wheel axis, the cylindrical lower ball raceway comprising a circumferentially-extending concave lower raceway profile on an inner surface, the lower raceway profile configured to receive a ball element precursor, the lower machining wheel configured to be rotatably disposed on the lower wheel axis, the cylindrical lower ball raceway comprising a lower abrasive material and/or comprising a non-abrasive material and configured to contain the abrasive media while the lower machining wheel is rotated, the upper raceway profile disposed above the lower raceway profile with the upper raceway profile facing the lower raceway profile, the upper wheel axis spaced apart from the lower wheel axis by a predetermined distance selected to capture the ball element precursor between the upper raceway profile and the lower raceway profile; and a bias member, the bias member operatively coupled to at least one of the upper machining wheel or the lower machining wheel configured to provide a predetermined load on the ball element precursor from the upper machining wheel and the lower machining wheel, the upper machining wheel and lower machining wheel configured to remove the ball element material upon rotation about the upper wheel axis and lower wheel axis, respectively, in the presence the abrasive media, the upper raceway profile and lower raceway profile selected to increase the sphericity of the ball element precursor upon removal of the ball element material; forming a drive assembly; forming a carrier assembly; attaching the upper machining wheel and the lower machining wheel to the carrier assembly; and attaching the upper machining wheel, lower machining wheel, and carrier assembly to the drive assembly.

27. A method of using a centerless ball element machining system, comprising: forming: an upper machining wheel comprising a cylindrical upper base and a cylindrical upper ball raceway, the cylindrical upper base comprising an upper wheel axis, the cylindrical upper ball raceway comprising a circumferentially-extending concave upper raceway profile on an inner surface, the upper raceway profile configured to receive a ball element precursor comprising a ball element material, the upper machining wheel configured to be rotatably disposed on the upper wheel axis, the cylindrical upper ball raceway comprising an upper abrasive material and/or comprising a non-abrasive material and configured to contain an abrasive media while the upper machining wheel is rotated; a lower machining wheel comprising a cylindrical lower base and a cylindrical lower ball raceway, the cylindrical lower base comprising a lower wheel axis, the cylindrical lower ball raceway comprising a circumferentially-extending concave lower raceway profile on an inner surface, the lower raceway profile configured to receive a ball element precursor, the lower machining wheel configured to be rotatably disposed on the lower wheel axis, the cylindrical lower ball raceway comprising a lower abrasive material and/or comprising a non-abrasive material and configured to contain the abrasive media while the lower machining wheel is rotated, the upper raceway profile disposed above the lower raceway profile with the upper raceway profile facing the lower raceway profile, the upper wheel axis spaced apart from the lower wheel axis by a predetermined distance selected to capture the ball element precursor between the upper raceway profile and the lower raceway profile; and a bias member, the bias member operatively coupled to at least one of the upper machining wheel or the lower machining wheel configured to provide a predetermined load on the ball element precursor from the upper machining wheel and the lower machining wheel, the upper machining wheel and lower machining wheel configured to remove the ball element material upon rotation about the upper wheel axis and lower wheel axis, respectively, in the presence the abrasive media, the upper raceway profile and lower raceway profile selected to increase the sphericity of the ball element precursor upon removal of the ball element material; a carrier assembly comprising an upper carrier plate and a lower carrier plate configured to rotatably carry the upper machining wheel and lower machining wheel and house the bias member; and a drive assembly comprising an electric motor and a rotatable motor shaft that is configured to rotate the carrier assembly carrier assembly and bias the bias member; disposing the ball element precursor between the upper raceway profile and the lower raceway profile; disposing a lubricant and/or an abrasive media in contact with the ball element precursor; operating the electric motor to rotate the upper machining wheel and the lower machining wheel thereby removing the ball element material from the ball element precursor; and stopping the electric motor and removing the ball element precursor when the ball element precursor comprises a predetermined size, a predetermined sphericity, or a predetermined surface finish, or a combination thereof.

28. The method of using a centerless ball element machining system of claim 27, further comprising: checking the upper raceway profile and/or the lower raceway profile for a predetermined wear characteristic; and if a predetermined wear characteristic is indicated, removing the upper ball raceway and/or the lower ball raceway having the predetermined wear characteristic; and replacing the upper ball raceway and/or the lower ball raceway with the upper raceway profile and/or the lower raceway profile.

29. The method of using a centerless ball element machining system of claim 28, further comprising: dispensing a flow of the lubricant and/or the abrasive media into contact with the ball element precursor while operating the electric motor.

Description:
CENTERLESS BALL ELEMENT MACHINING SYSTEM, MACHINING WHEEL THEREFOR, AND METHOD OF MAKING AND USING THE SAME

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This Patent Cooperation Treaty (PCT) utility patent application claims priority to US Provisional Patent Application 62/886,441 filed on August 14, 2019, which is hereby incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

[0002] The subject invention relates generally to a centerless ball element machining system, machining wheels therefor, and a method of making and using the same to machine spherical ball elements of various materials for many applications, more particularly the subject invention relates generally to centerless ball element machining system, machining wheels therefor, and a method of making and using the same to machine spherical ball elements of ceramic materials, such as silicon nitride, for many applications.

BACKGROUND

[0003] Bearings comprising rolling or Tollable bearing elements of various types are used in an enormous number of applications, products, and technologies to enable relative rotation between one rotatable member and another member. Bearings comprise two general types based on the rolling or Tollable bearing elements (sometimes referred to simply as “elements” or “bearings”) used to bear the load, spherical ball elements and cylindrical roller elements. These bearing elements are generally housed within bearing races that support the bearings and are configured for attachment to the rotatable member or members. The ball elements, roller elements and bearing races generally have highly polished surfaces and low surface roughness in order to reduce the amount of friction associated with the bearing.

[0004] The current ball element manufacturing process begins with the forming of a ball element precursor (or ball element blank) comprising a rough spherical shape. The ball machining process requires the removal of a significant amount of material from the ball element precursor in order to form polished spherical balls suitable for low friction bearings. Typically, this is done by a combination of grinding and lapping processes that are performed by placing the ball element precursors between opposed concentric stationary and rotating cylindrical lapping plates or disks that include opposed concentric grooves filled with ball element precursors (e.g. balls) and an abrasive as shown in FIGS. 20 and 21. In the device of FIGS. 20 and 21, two opposed superimposed lapping plates are spaced by a working gap and are rotated relative to each other. The upper plate is held stationary and the lower plate is rotated. The lower plate has in its side facing the upper plate a plurality (e.g. three) concentric grooves for lapping ball element precursors by relative rotation of the two plates. The plates are encompassed by a rotary magazine including a circular guide path for balls to be lapped.

A radial recess in the stationary plate connects the working gap with the guide path. The rotation of the plate causes the ball element precursors to rotate within the grooves and the abrasive causing removal of material from the ball element precursors. Selective and progressive reduction of the particle size of the abrasive is used to progressively achieve the spherical shape and size and desired surface finish or roughness of the finished ball elements.

[0005] The grinding and lapping processes permit large numbers of ball element precursors to be processed simultaneously. The quantity depends on the size of the ball element precursors. The present understanding of rolling motion and ball dynamics indicates that there is a significant amount of rolling motion and limited sliding motion of the balls in the contact ellipse that is formed between the balls and the rolling surfaces as shown in FIG. 22. The predominance of the rolling motion compared to the sliding motion results in the rate of material removal being relatively slow compared to other material removal processes.

[0006] While very useful, current grinding and lapping processes are very time consuming, particularly for harder materials. The rate of material removal is inversely proportional to the hardness of the bearing material (e.g. generally significantly lower for ceramics as compared to metals). These grinding and lapping processes and equipment have known limitations, including a slow rate of material removal, due to the fact that they result in a large amounts of rolling motion of the ball element precursors in the grooves and a limited amount of sliding of the ball element precursors that in turn results in a low rate of material removal (i.e. wear) and longer processing times. Therefore, it is generally desirable in grinding and lapping processes and equipment to increase the amount of sliding and the rate of material removal (i.e. wear) to reduce processing time and increase throughput. [0007] For example, as shown in FIG. 22 the contact ellipses can be very small if the lapping plates are large. The lapping plates form two small concave and two convex interfaces to the ball element precursors. These interfaces become smaller as the lapping plate size and number of balls between the plates increase. Sliding is limited to the rotating speed of the ball element precursors. High lap speeds reduce ball rotation and increase ball sliding within the lapping plates and reduce sphericity, which is very undesirable. In addition, current grinding and lapping processes are known to produce ball elements that include various manufacturing and/or equipment related defects, including cracking. Therefore, while it is generally desirable to increase sliding and wear (i.e. rate of material removal), it is generally not possible to do so with existing lapping and grinding processes for the reasons mentioned.

[0008] Centerless grinding processes that employ opposed rotating abrasive wheels as shown in FIG. 23 provide a high degree of sliding contact between the grinding wheels and the workpiece, and thus high wear and high rates of material removal, and provide components with tight tolerances and excellent surface finishes. Centerless grinding processes are currently used to machine many materials into precision cylindrical shapes with very accurate cross-sectional roundness, dimensional tolerances, and very fine surface finishes, including low surface roughness. However, centerless grinding processes have not been used in the manufacture of ball elements because the ball elements are generally spherical, not cylindrical.

[0009] Recently, ceramic bearings, and more specifically silicon nitride ball elements, offer significant performance advantages in many bearing types and other applications such as ball valves. The hardness, operating temperature range, and wear resistance of ceramics, particularly silicon nitride, offer advantages in many bearing applications, but the same properties make it difficult and expensive to process ceramic bearings into the desired shapes, particularly spherical polished balls. Thus, the process limitations of prior art processes noted above that apply generally to all bearing materials are exacerbated in the case of ceramic bearings due to their increased hardness and wear resistance.

[0010] Planetary or epicyclic gears are used to promote the rotation of one or more planetary gears about a sun gear within a ring gear as shown in FIG. 24. They are used to provide relative rotation of the gears and associated members in many applications. However, they are not employed in existing lapping/grinding processes utilized on ball element precursors to manufacture ball elements.

[0011] Therefore, it would be very desirable to develop improved bearing manufacturing processes and equipment for making ball elements, particularly ceramic ball elements, that increase the amount of sliding of the balls and the rate of material removal and thereby avoid the current process and equipment limitations mentioned and that also provide improved bearing elements. It would be very desirable to develop material removal processes that provide high rates of material removal similar to centerless grinding. It would also be desirable to provide lapping/grinding processes for ball elements that utilize well established technology to provide relative rotation of the lapping/grinding members, such as planetary or epicyclic gear assemblies.

SUMMARY OF THE INVENTION

[0012] In one embodiment, a centerless ball element machining system is disclosed. The centerless ball element machining system comprises an upper machining wheel comprising a cylindrical upper base and a cylindrical upper ball raceway, the cylindrical upper base comprising an upper wheel axis, the cylindrical upper ball raceway comprising a circumferentially-extending concave upper raceway profile on an inner surface, the upper raceway profile configured to receive a ball element precursor comprising a ball element material, the upper machining wheel configured to be rotatably disposed on the upper wheel axis, the cylindrical upper ball raceway comprising an upper abrasive material or an upper non-abrasive material and configured to contain a lubricant or an abrasive media while the upper machining wheel is rotated. The centerless ball element machining system also comprises a lower machining wheel comprising a cylindrical lower base and a cylindrical lower ball raceway, the cylindrical lower base comprising a lower wheel axis, the cylindrical lower ball raceway comprising a circumferentially-extending concave lower raceway profile on an inner surface, the lower raceway profile configured to receive the ball element precursor comprising the ball element material, the lower machining wheel configured to be rotatably disposed on the lower wheel axis, the cylindrical lower ball raceway comprising a lower abrasive material or a lower non-abrasive material and configured to contain the lubricant or the abrasive media while the lower machining wheel is rotated, the upper raceway profile disposed above the lower raceway profile with the upper raceway profile facing the lower raceway profile, the upper wheel axis spaced apart from the lower wheel axis by a predetermined distance selected to capture the ball element precursor between the upper raceway profile and the lower raceway profile. The centerless ball element machining system also comprises a bias member, the bias member operatively coupled to at least one of the upper machining wheel or the lower machining wheel configured to provide a predetermined load on the ball element precursor from the upper machining wheel and the lower machining wheel, the upper machining wheel and lower machining wheel configured to remove a ball element material from the ball element precursor upon rotation about the upper wheel axis and lower wheel axis, respectively, in the presence the abrasive media, the upper raceway profile and lower raceway profile selected to increase the sphericity of the ball element precursor upon removal of the ball element material.

[0013] In another embodiment, a centerless ball element machining wheel is disclosed.

The centerless ball element machining wheel comprises a cylindrical base and a cylindrical ball raceway, the cylindrical base comprising a wheel axis, the cylindrical raceway comprising a circumferentially-extending concave raceway profile on an inner surface, the raceway profile configured to receive a ball element precursor comprising a ball element material, the machining wheel configured to be rotatably disposed on the wheel axis, the cylindrical ball raceway comprising an abrasive material and/or a non-abrasive material configured to contain an abrasive media while the machining wheel is rotated.

[0014] In another embodiment, a method of making a centerless ball element machining system is disclosed. The method of making a centerless ball element machining system comprises forming an upper machining wheel comprising a cylindrical upper base and a cylindrical upper ball raceway, the cylindrical upper base comprising an upper wheel axis, the cylindrical upper ball raceway comprising a circumferentially-extending concave upper raceway profile on an inner surface, the upper raceway profile configured to receive a ball element precursor comprising a ball element material, the upper machining wheel configured to be rotatably disposed on the upper wheel axis, the cylindrical upper ball raceway comprising an upper abrasive material and/or comprising a non-abrasive material and configured to contain an abrasive media while the upper machining wheel is rotated; a lower machining wheel comprising a cylindrical lower base and a cylindrical lower ball raceway, the cylindrical lower base comprising a lower wheel axis, the cylindrical lower ball raceway comprising a circumferentially-extending concave lower raceway profile on an inner surface, the lower raceway profile configured to receive a ball element precursor, the lower machining wheel configured to be rotatably disposed on the lower wheel axis, the cylindrical lower ball raceway comprising a lower abrasive material and/or comprising a non-abrasive material and configured to contain the abrasive media while the lower machining wheel is rotated, the upper raceway profile disposed above the lower raceway profile with the upper raceway profile facing the lower raceway profile, the upper wheel axis spaced apart from the lower wheel axis by a predetermined distance selected to capture the ball element precursor between the upper raceway profile and the lower raceway profile; and a bias member, the bias member operatively coupled to at least one of the upper machining wheel or the lower machining wheel configured to provide a predetermined load on the ball element precursor from the upper machining wheel and the lower machining wheel, the upper machining wheel and lower machining wheel configured to remove the ball element material upon rotation about the upper wheel axis and lower wheel axis, respectively, in the presence the abrasive media, the upper raceway profile and lower raceway profile selected to increase the sphericity of the ball element precursor upon removal of the ball element material. The method of making a centerless ball element machining system also comprises forming a drive assembly. The method of making a centerless ball element machining system also comprises forming a carrier assembly. The method of making a centerless ball element machining system also comprises attaching the upper machining wheel and the lower machining wheel to the carrier assembly. The method of making a centerless ball element machining system also comprises attaching the upper machining wheel, lower machining wheel, and carrier assembly to the drive assembly.

[0015] In yet another embodiment, a method of using a centerless ball element machining system is disclosed. The method of using a centerless ball element machining system comprises forming an upper machining wheel comprising a cylindrical upper base and a cylindrical upper ball raceway, the cylindrical upper base comprising an upper wheel axis, the cylindrical upper ball raceway comprising a circumferentially-extending concave upper raceway profile on an inner surface, the upper raceway profile configured to receive a ball element precursor comprising a ball element material, the upper machining wheel configured to be rotatably disposed on the upper wheel axis, the cylindrical upper ball raceway comprising an upper abrasive material and/or comprising a non-abrasive material and configured to contain an abrasive media while the upper machining wheel is rotated; a lower machining wheel comprising a cylindrical lower base and a cylindrical lower ball raceway, the cylindrical lower base comprising a lower wheel axis, the cylindrical lower ball raceway comprising a circumferentially-extending concave lower raceway profile on an inner surface, the lower raceway profile configured to receive a ball element precursor, the lower machining wheel configured to be rotatably disposed on the lower wheel axis, the cylindrical lower ball raceway comprising a lower abrasive material and/or comprising a non-abrasive material and configured to contain the abrasive media while the lower machining wheel is rotated, the upper raceway profile disposed above the lower raceway profile with the upper raceway profile facing the lower raceway profile, the upper wheel axis spaced apart from the lower wheel axis by a predetermined distance selected to capture the ball element precursor between the upper raceway profile and the lower raceway profile; and a bias member, the bias member operatively coupled to at least one of the upper machining wheel or the lower machining wheel configured to provide a predetermined load on the ball element precursor from the upper machining wheel and the lower machining wheel, the upper machining wheel and lower machining wheel configured to remove the ball element material upon rotation about the upper wheel axis and lower wheel axis, respectively, in the presence the abrasive media, the upper raceway profile and lower raceway profile selected to increase the sphericity of the ball element precursor upon removal of the ball element material; a carrier assembly comprising an upper carrier plate and a lower carrier plate configured to rotatably carry the upper machining wheel and lower machining wheel and house the bias member; and a drive assembly comprising an electric motor and a rotatable motor shaft that is configured to rotate the carrier assembly carrier assembly and bias the bias member. The method of using a centerless ball element machining system also comprises disposing the ball element precursor between the upper raceway profile and the lower raceway profile. The method of using a centerless ball element machining system also comprises disposing a lubricant and/or an abrasive media in contact with the ball element precursor. The method of using a centerless ball element machining system also comprises operating the electric motor to rotate the upper machining wheel and the lower machining wheel thereby removing the ball element material from the ball element precursor. The method of using a centerless ball element machining system also comprises removing the ball element precursor when the ball element precursor comprises a predetermined size, a predetermined sphericity, or a predetermined surface finish, or a combination thereof.

[0016] The above features and advantages and other features and advantages of the invention are readily apparent from the following detailed description of the invention when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Other features, advantages and details appear, by way of example only, in the following detailed description of embodiments, the detailed description referring to the drawings in which:

[0018] FIG. 1 is a perspective view of a solid model of an embodiment of a ball element machining system comprising an embodiment of an upper ball element machining wheel and an embodiment of a lower ball element machining wheel and also comprising a ball element precursor, in an assembled condition, as described herein;

[0019] FIG. 2 is an exploded view of the embodiments of FIG. 1;

[0020] FIG. 3 is a side view of the embodiments of FIG. 1;

[0021] FIG. 4A is a perspective view of an embodiment of an upper carrier bearing comprising a ring gear on an inner diameter thereof, as described herein;

[0022] FIG. 4B is a perspective view of an embodiment of a lower carrier bearing, as described herein;

[0023] FIG. 5 is a top view of the embodiment of the ball element machining system and ball element machining wheels of FIG. 1 with the machining wheels in a ball element precursor load position, as described herein;

[0024] FIG. 6A is a partial cutaway top view of the embodiments of the ball element machining system and ball element machining wheels of FIG. 1 with the machining wheels in a ball element precursor machining position, as described herein;

[0025] FIG. 6B is an enlargement of region 6B of FIG. 6A;

[0026] FIG. 7A is a partial cross-section view of a ball element precursor disposed in the embodiment of the upper and lower ball element machining wheels of the ball element machining system of FIG. 1 in a ball machining position schematically illustrating the application of forces (loads) on the ball element precursor and the movement of the raceways of the machining wheels as a function of machining time and ball element material removal, as described herein;

[0027] FIG. 7B is a side view of a ball element precursor, as described herein;

[0028] FIG. 8 is another partial cross-section view of a ball element precursor disposed in another embodiment of the upper and lower ball element machining wheels and respective raceways of the ball element machining system in a ball machining position schematically illustrating elliptical raceway profiles on the ball element machining wheels and describing the contact ellipse (ball contact area);

[0029] FIG. 9A is another partial cross-section view of a ball element precursor disposed in another embodiment of the upper and lower ball element machining wheels and respective raceways of the ball element machining system in a ball machining position schematically illustrating another embodiment of the application of forces (loads) on the ball element and machining wheel raceway movement as a function of machining time and ball element material removal, as described herein;

[0030] FIG. 9B is a partial cross-section view of a ball element precursor disposed in another embodiment of upper and lower ball element machining wheels and respective raceways of a ball element machining system in a ball machining position illustrating another embodiment of the application of forces (loads) on the ball element and machining wheel raceway movement as a function of machining time and ball element material removal, and illustrating an embodiment of a gothic arch shaped raceway of the upper machining wheel, as described herein;

[0031] FIG. 10 is schematic illustration of ball element dynamic forces and velocities applied by the rotating upper and lower machining wheels during operation of the ball element machining system;

[0032] FIG. 11 is a schematic illustration of ball dynamic forces and sliding movement patterns in the contact ellipse in a ball machining position and a condition where the velocity (Vi) of the lower machining wheel is greater than the velocity (V2) of the upper machining wheel; [0033] FIG. 12 is a schematic illustration of ball dynamic forces and sliding movement patterns in the contact ellipse in a ball machining position and condition where the velocity (Vi) of the lower machining wheel is equal to the velocity (V2) of the upper machining wheel;

[0034] FIG. 13 is a side view of another embodiment of a ball element machining system comprising another embodiment of upper and lower ball element machining wheels, as described herein;

[0035] FIG. 14 is a perspective view of another embodiment of a ball element machining system comprising another embodiment of upper and lower ball element machining wheels that is attached to a machining table, as described herein;

[0036] FIG. 15 is a side view of another embodiment of a ball element machining system comprising another embodiment of upper and lower ball element machining wheels comprising a plurality of stacked upper and lower ball element machining wheels configured to simultaneously machine a plurality of ball element precursors, as described herein;

[0037] FIG. 16 is a side view of another embodiment of a ball element machining system comprising another embodiment of upper and lower ball element machining wheels comprising a plurality of concentric raceways that are configured to simultaneously machine a plurality of ball element precursors, as described herein;

[0038] FIG. 17A is a partially exploded perspective view of another embodiment of a ball element machining system comprising another embodiment of upper and lower ball element machining wheels comprising a plurality of radially spaced lower ball element machining wheels spaced about a central upper ball element machining wheel and configured to simultaneously machine a plurality of ball element precursors, as described herein;

[0039] FIG. 17B is a top view of the embodiment of FIG. 17A;

[0040] FIG. 18 is a flowchart of a method of making a ball element machining system, as described herein;

[0041] FIG. 19 is a flowchart of a method of using a ball element machining system, as described herein;

[0042] FIG. 20 is a schematic top view of a prior art ball element lapping system; [0043] FIG. 21 is a schematic cross-sectional view of the prior art ball element lapping system of FIG. 20 taken along Section II;

[0044] FIG. 22 is a schematic cross-sectional view of the loads applied to a prior art ball element precursor in the prior art ball element lapping system of FIG. 20;

[0045] FIG. 23 is a schematic perspective view of a prior art centerless grinding system ; and

[0046] FIG. 24 is a schematic perspective view of a prior art epicyclic gear assembly.

In the figures, various elements may be described as circular or cylindrical and the like and illustrated with curves comprised of a plurality of what appear to be interconnected line segments that approximate a curved shape. In such instances, one of ordinary skill will understand that the illustrations actually represent smooth circular or cylindrical lines and surfaces and that the segmentation is due to limitations of the equipment used to render the figures. The terms circular or cylindrical and the like should be understood as having the shapes shown in FIG. 17 A.

DESCRIPTION OF THE EMBODIMENTS

[0047] Referring to FIGS. 1-17B, and particularly to FIGS. 1-6, a centerless ball element machining system 10 is disclosed. The centerless ball element machining system 10 comprises a selectively rotatable upper machining wheel 12 comprising a cylindrical upper base 14 and a cylindrical upper ball raceway 16. The cylindrical upper base 14 comprises an upper wheel axis 18, which is also the axis of the upper shaft as described herein. The cylindrical upper ball raceway 16 comprises a circumferentially-extending concave upper raceway profile 20 on an inner surface 22 proximate the periphery of the cylindrical upper base 14. The concave upper raceway profile 20 is configured to receive and be brought into contact with an upper contact patch or portion 29 of the surface of the precursor of a ball element 24, or ball element precursor 24, comprising a ball element precursor material 26. The upper machining wheel is configured to be rotatably disposed on the upper wheel axis 18. The ball element precursor 24 is partially or substantially spherical, or spherical. As used herein, substantially or partially spherical means having a generally spherical shape or joined hemispherical shapes that may include a raised portion such as a central circumferential protrusion 25 (FIG. 7B), including a parting line 27 that is sometimes associated with the manufacturing method used to form the ball element precursor material 26 into ball element precursor 24. The cylindrical upper ball raceway 16 comprising an upper abrasive material 28 or an upper non-abrasive material 30 and configured to contain or retain, or at least partially contain or retain, a lubricant 31 or an abrasive media 35 while the upper machining wheel 12 is rotated. The concave upper raceway profile 20 comprises a concave curve. In one embodiment, the concave upper raceway profile 20 comprises an elliptical curve, including an elliptical curve defined as a portion or segment of an ellipse (e.g. FIG. 7A). In one embodiment, the curvature of the concave curve, such as radius of curvature of the elliptical concave upper raceway profile 20 about the foci of the ellipse is greater than the radius of curvature of the spherical ball element precursor 24. In another embodiment, the concave upper raceway profile 20 comprises opposed intersecting concave curves opposed about the vertical axis 21, including opposed intersecting concave curves defined as a portion or segment of an arch, such as, for example, a gothic arch (e.g. FIG. (9B). In one embodiment, the opposed intersecting concave curves may comprise mirror images of one another about the vertical axis 21. The concave curve, or opposing concave curves, of the concave upper raceway profile 20 may be defined by any mathematical function capable of defining a concave curve or curve segment or arc, such as mathematical functions that comprise a circle, ellipse, parabola, hyberbolic cosine, and the like.

[0048] The centerless ball element machining system 10 also comprises a selectively rotatable lower machining wheel 32 comprising a cylindrical lower base 34 and a cylindrical lower ball raceway 36. The cylindrical lower base 34 comprises a lower wheel axis 38, which is also the axis of the lower shaft as described herein. The cylindrical lower ball raceway 36 comprises a circumferentially-extending concave lower raceway profile 40 on an inner surface 42 proximate the periphery of the cylindrical lower base 34. The lower raceway profile 40 is configured to receive and be brought into contact with a lower contact patch or portion 31 of the surface of the ball element precursor 24 comprising a ball element precursor material 26. It must be appreciated that the location of the upper and lower contact patches or portions 29, 31 are constantly changing as the ball element machining system 10 is operated as described herein and the ball element precursor 24, or precursors, rotate, slide and spin within while in pressed engagement with the upper and lower machining wheels 12, 32 and as described and illustrated in FIGS. 5-12, for example. The lower machining wheel 32 is configured to be rotatably disposed on the lower wheel axis 38. The cylindrical lower ball raceway 36 comprises a lower abrasive material 48 or a lower non-abrasive material 50 and is configured to contain or retain, or at least partially contain or retain, the lubricant 31 or the abrasive media 35 while the lower machining wheel 32 is rotated. The concave lower raceway profile 40 comprises a concave curve. In one embodiment, the concave lower raceway profile 40 comprises an elliptical curve, including an elliptical curve defined as a portion or segment of an ellipse. In one embodiment, the curvature of the concave curve, such as radius of curvature of the elliptical concave upper raceway profile 40 about the foci of the ellipse is greater than the radius of curvature of the spherical ball element precursor 24. The concave curve of the concave lower raceway profile 40 may be defined by any mathematical function capable of defining a concave curve or curve segment or arc, such as mathematical functions that define a circle, ellipse, parabola, hyberbolic cosine, and the like. The concave upper raceway profile 20 is disposed above and opposes the concave lower raceway profile 40 with the upper raceway profile opposed from and facing the lower raceway profile. In one embodiment, the concave curve, or opposing concave curves, of the concave upper raceway profile 20 and the concave curve of the concave lower raceway profile 40 may comprise the same concave curve. In another embodiment, the concave curve, or opposing concave curves, of the concave upper raceway profile 20 and the concave curve of the concave lower raceway profile 40 may comprise different concave curves.

[0049] The upper wheel 12 and upper wheel axis 18 are spaced apart from the lower wheel 32 and the lower wheel axis 38 by a predetermined distance selected to capture the ball element precursor 24 between the upper raceway profile 20 and the lower raceway profile 40 and the upper and lower wheels 20, 40 are configured to apply a predetermined load to the ball element precursor 24, as described herein. It will be understood that as a result of material removal through grinding and lapping as described herein, the ball element precursor 24 is transformed as a function of time into a spherical ball element 24’ comprising a ball element material 26’ and that the ball element precursor material 26 is thus also the ball element material 26’ although the surface finish, including surface roughness, waviness and other characteristics of these materials are different . In one embodiment, the spherical ball element 24’ comprises a predetermined bearing size and grade, comprising a predetermined sphericity and a predetermined surface finish or smoothness, including predetermined surface roughness and a predetermined surface waviness as these terms are used in the art of ball bearing manufacture.

[0050] The centerless ball element machining system 10 also comprises a bias member 52 (FIG. 3). The bias member 52 is operatively coupled to at least one of the upper machining wheel 12 and/or the lower machining wheel 32 and is configured to provide a predetermined load on the ball element precursor 24 from the upper machining wheel 12 and the lower machining wheel 32 through the upper ball raceway 16 and the lower ball raceway 36, respectively. The upper machining wheel 12 and lower machining wheel 32 are configured to remove the ball element material 26 from the ball element precursor 24 upon rotation about the upper wheel axis 18 and lower wheel axis 38, respectively, in the presence of the abrasive media 35, the upper raceway profile 20 and lower raceway profile 40 and their curvatures are selected and configured to increase the sphericity of the ball element precursor 24 upon removal of the ball element material 26.

[0051] Referring to FIGS. 1-3, in one embodiment of the centerless ball element machining system 10, each of rotatable upper wheel axis 18/upper gear shaft 118 and lower wheel axis 38/lower gear shaft 98 may contain the following upper and lower elements, respectively: the shaft 118, 98, bearing 116, 100, planetary gear 76, 78, and machining wheel 12, 32 with the respective raceway profile 20, 40. The upper gear shaft 118 and lower gear shaft 98 and respective upper machining wheel 12 and lower machining wheel 32 may rotate at the same speed or at different speeds and in the same direction or in opposite directions. The axis/shaft can also be mounted to a carrier similar to a planetary gear system so the respective axes/shafts/wheels can also orbit around the ball element precursor 24. Material removal can be accomplished by providing upper and lower ball raceways 16, 36 made of a grinding medium or any abrasive material or non-abrasive material suitable for use as a ball raceway and/or by dispensing an abrasive media comprising abrasive particles into the ball raceways to create wear.

[0052] In one embodiment, the upper machining wheel 12 comprises a plurality radially spaced, circumferentially-extending slots 54 or other suitable openings, such as holes, that are configured to pass through or load the ball element precursor 24 for placement between the upper raceway profile 20 and the lower raceway profile 40. In one embodiment, the circumferentially-extending slots 54 have a width and a length and rounded semicircular shaped ends with a radius of curvature greater than or equal to the radius of curvature of the ball element precursors 24 in order to promote their loading over the entire length of the circumferentially-extending slots 54. In the embodiment of FIGS. 16A and 16B, the plurality of radially spaced circumferentially-extending slots 54 may be replaced with a plurality of radially spaced circular openings or holes 54’ having a predetermined diameter that is configured to receive and pass the ball element precursors 24 through them.

[0053] In one embodiment, the upper raceway profile 20 comprises an upper elliptical shape, and wherein the lower raceway profile 40 comprises a lower elliptical shape as described herein (FIG. 8). In one embodiment, the upper raceway profile 20 and upper elliptical shape and lower raceway profile 40 and lower elliptical shape may comprise the same shapes.

[0054] In one embodiment, the centerless ball element machining system 10 further comprises a drive assembly 56. The drive assembly 56 is operably coupled to and configured to rotate the upper machining wheel 12 and the lower machining wheel 32.

[0055] In one embodiment, the drive assembly 56 comprises an epicyclic gear set 58 and an electric motor 60 comprising a motor shaft 62 configured for selectively controllable rotation about a motor axis 64 that is rotatably and operably coupled to the epicyclic gear set 58 through the clutch 94 and torsion spring 96 (e.g. FIG. 3). The epicyclic gear set 58 comprises a planetary gear 66, or a plurality of planetary gears, and a ring gear 68. In one embodiment, the epicyclic gear set 58 also comprises a sun gear 70 (FIG. 17A). The epicyclic gear set 58, including the diameters of the planetary gear(s) 66, ring gear 68 and sun gear 70, may be selected together with the electric motor 60 to provide a predetermined gear reduction ratio and range of rotational speeds and torques of the upper machining wheel 12 and lower machining wheel 32. The electric motor 60 may comprise any suitable type of electric motor, including all manner of AC and DC powered motors, that are selectively controllable to control a motor speed and a motor torque through a suitable controller 61. In one embodiment, the controller 61 comprises a microcomputer-based programmable logic controller configured for at least one of sequential relay control, wheel position control, motor control, fluid or liquid dispensing control, process control, wheel/ball element pressure or force control, ball pick and placement control, distributed control of one or more centerless ball element machining systems, and networking. [0056] In one embodiment, the epicyclic gear set 58 comprises a ring gear 68 configured for attachment to a machining table 72 configured to support the epicyclic gear set 58 and system 10 proximate a gear opening 74 configured to receive the epicyclic gear set, an upper wheel planetary gear 76 configured for selective attachment to and detachment from the upper machining wheel 12 and configured for toothed engagement within the ring gear and rotation about the upper wheel axis 18. The epicyclic gear set 58 also comprises a lower wheel planetary gear 78 configured for selective attachment to and detachment from the lower machining wheel 32 and configured for toothed engagement within the ring gear 68 and rotation about the lower wheel axis 38. The upper wheel planetary gear 76 is spaced apart from the lower wheel planetary gear 78.

[0057] Referring again to FIGS. 1 -3, in one embodiment, the centerless ball element machining system 10 further comprising a carrier assembly 80 (e.g. FIG. 2). The carrier assembly 80 comprises a lower carrier assembly 81 comprising a lower carrier plate 82 that comprises a lower hub 84, a plurality of outwardly extending, radially spaced lower spokes 86 attached to the lower hub and extending to a circumferential lower rim 88 and defining a plurality of radially spaced, circumferentially-extending lower slots 90 disposed therebetween. The lower hub 84 is configured for attachment to the motor shaft 62 and comprising a downwardly extending, upwardly opening clutch pocket 92 configured to receive a selectively and variably engageable/disengageable clutch 94 and a torsion spring 96 that are configured to be disposed on the motor shaft 62 within the clutch pocket 92. The lower carrier plate 82 comprises a lower gear shaft 98 attached thereto and configured to receive a lower gear bearing 100 that is configured for attachment to and rotatable disposition between the lower gear shaft 98 and the lower planetary gear 78. The lower carrier plate 82 configured for rotatable engagement with the ring gear 68. The lower carrier plate 82 also may comprise a clutch pocket 92 configured to house the clutch 94 as described herein.

[0058] The carrier assembly 80 also comprises an upper carrier plate assembly 101 comprising an upper carrier plate 102 that comprises an upper hub 104, a plurality of outwardly extending, radially spaced upper spokes 106 attached to the upper hub and extending to a circumferential upper rim 108 and defining a plurality of radially spaced, circumferentially-extending upper slots 110 disposed therebetween. The upper hub 104 comprises a shaft portion 112 configured for insertion into and locking torque transfer engagement with the torsion spring 96. The upper carrier plate 102 comprises an upper gear shaft 118 attached thereto and configured to receive an upper gear bearing 116 that is configured for attachment to and rotatable disposition between the upper gear shaft 118 and the upper wheel planetary gear 76, the lower gear shaft 98 configured to extend through one of the circumferentially-extending upper slots 110, the upper carrier plate 102 configured for rotatable engagement with the ring gear 68.

[0059] The lower carrier plate assembly 81 and the upper carrier plate assembly 101 are each built on bearings and can rotate independently of each other. The torsion spring 96 and clutch 94 acts between the lower carrier plate assembly 81 and the upper carrier plate assembly 101 to bias and move the upper machining wheel 12 and upper wheel axis 18 toward the lower machining wheel 32 and lower wheel axis 38 and thereby provide pressing engagement of the upper ball raceway 16 lower ball raceway 36 against the ball element precursor 24with a predetermined bias force or bias load.

[0060] In one embodiment of the centerless ball element machining system 10, the carrier assembly 80 further comprises an upper carrier bearing 120 configured for disposition proximate the ring gear 68 and a peripheral edge 122 of the upper carrier plate 102 and comprising an upper inner bearing race 124 and an upper outer bearing race 126 and upper bearing elements 125 rotatably disposed between them as shown in FIGS. 1-4B. The upper inner bearing race 124 configured for pressed engagement onto an outer circumference 128 of the ring gear 68, the upper outer bearing race 126 configured for attachment to the upper carrier plate 102, the upper carrier bearing 120 providing rotatable engagement of the upper carrier plate and the ring gear.

[0061] The carrier assembly 80 also comprises a lower carrier bearing 130 configured for disposition proximate the upper carrier bearing 120 and a peripheral edge 132 of the lower carrier plate 82 and comprising a lower inner bearing race 134 and a lower outer bearing race 136 and lower bearing elements 135 rotatably disposed between them as shown in FIGS. 1- 4B. The lower inner bearing race 134 is configured for attachment to the lower carrier plate 82, the lower outer bearing race 136 configured for attachment to the upper carrier plate 102 and the upper outer bearing race 126, the lower carrier bearing 130 providing rotatable engagement of the lower carrier plate 82 and the upper carrier bearing 120. [0062] In one embodiment of the centerless ball element machining system 10, the selectively and variably engageable/disengageable clutch 94 and the torsion spring 96 comprise the bias member 52, and wherein upon rotation of the electric motor 60 and engagement of the clutch, a torque is applied to the torsion spring causing the torsion spring to wind up according to a predetermined spring rate of the torsion spring and apply the predetermined load (L) on the ball element precursor 24 from the upper machining wheel 12 and the lower machining wheel 32. The clutch 94 and its constituent parts and the electric motor 60 and its constituent parts together with torsion spring 96 comprise a drive assembly 56 for providing motive power to the centerless ball element machining system 10.

[0063] Referring to FIGS. 5-12, the operation of the centerless ball element machining system 10 and machining of the ball element precursors 24 is explained. Referring to FIGS.

5, the loading and unloading of the ball element precursor 24 is explained. The ball is loaded between the raceways by moving one of upper wheel axis 18 and lower wheel axis 38 relative to the other to increase and expose the cavity formed by the opposing raceways for insertion of a ball element precursor 24. The removal of the finished ball element 24’ can occur in a similar manner. In one example, the electric motor 60 creates torque. The lower carrier assembly 81 is held stationary /blocked such that the lower planetary gear 78 cannot orbit within the ring gear 68. If the centerless ball element machining system 10 does not contain a ball element precursor 24, the upper carrier assembly 101 is rotated to an angle less than the 180° “home” position to load the ball element precursor 24. The ball element precursor 24 is fed through holes 54’ or circumferentially-extending slots 54 in the upper machining wheel 12. If the centerless ball element machining system 10 contains, and has completed the machining of, a ball element precursor 24 to produce a finished ball element 24’ and is in the “machining complete” or stop position, the finished ball element 24’is removed and a new ball element precursor 24 is fed through the holes 54’ or circumferentially-extending slots 54. The upper carrier assembly 101 is rotated and returned by the electric motor or torsion spring forces to an angular position slightly less than the straight line 180° “home” position that comprises a “machining start” position.

[0064] Referring to FIGS. 6A-6B, controlling of the final ball size during ball element precursor 24 machining is explained. After ball element precursor 24 insertion, the upper carrier assembly 101 is returned by the torsion spring 96 into a position in which load equilibrium is established (angle less than 180°, but greater than the load position). The upper wheel axis 18 of the upper gear shaft 118 and the lower wheel axis 38 of the lower gear shaft 98 move farther apart. A controlled or predetermined torsion bias or load (L) is maintained between the upper carrier assembly 101 and lower carrier assembly 81 that is converted into or provides a predetermined compressive load on the ball element precursor 24 through pressure exerted by the upper and lower ball raceways 16, 36. As the ball precursor material 26 is removed from the ball element precursor 24 the torsion load will increase the distance between the upper wheel axis 18 and lower wheel axis 38 and the angle between the upper carrier assembly 101 and lower carrier assembly 81 moves closer to the “home” position (e.g. 180°). This movement maintains the controlled or predetermined compressive load (L) on the ball element precursor 24. There is a positive upper stop 138 on the upper carrier assembly 101 and a corresponding lower stop 139 on the lower carrier assembly 81 that are configured to engage one another and stop the relative rotation of the carrier assemblies and andthat will not permit the upper wheel axis 18 of upper carrier assembly 101 to move beyond a predetermined angle that defines the “home” position (e.g. 180° angular separation) from lower wheel axis 38 of lower carrier assembly 81. The upper stop 138 and lower stop 139 may be placed on any desired portion of their upper and lower carrier assemblies 101,81 that provides engagement sufficient to stop their relative rotation. As the distance between the upper axis 18 and lower axis 38 is increased the upper/lower raceways 16, 36 exert a predetermined compressive load (L) or force on the ball element precursor 24. As the ball element precursor 24 size is reduced the distance between the upper wheel axis 18 and lower wheel axis 38 is increased to maintain the predetermined compressive load (L) or force. In a planetary gear machine design, a controlled torsion between the carrier assemblies increases the distance between the upper wheel axis 16 and lower wheel axis 36 and imparts a predetermined compressive load (L) on the ball element precursor 24 that resists the upper carrier assembly’s 101 ability to return to the “home” position (e.g. 180 ° angle). As the material is removed from the ball element precursor and its size reduced the shaft axis on the carriers move closer to the “home” position (e.g. 180°) or stop 138.

[0065] Referring to FIGS. 5-7B, the predetermined machining loads and upper/lower raceway 16, 36 movement during ball element precursor sizing and ball precursor material 26 removal during machining is explained. The torsion load from the torsion spring 96 forces the center of the upper wheel axis 18 back toward a “home” angular position (e.g. 180°). As the angle between the upper/lower axes 18, 38 moves closer to 180° of angular separation and the shaft axes continue to separate - the upper/lower raceways 16, 36 move closer to each other which accommodates the shrinking ball element precursor 24 and maintains a predetermined compressive load on the ball element precursor 24. The maintenance of the predetermined compressive load is necessary to provide sliding motion of the ball element precursor 24 and promote wear and removal of the ball element precursor material 26. The position of the load and ball element precursor 24 contact with the raceway profiles 20, 40 changes as the ball blank/ball element precursor 24 is reduced in size. The cavity between the upper/lower raceways 16, 36 is reduced as the distance between the upper/lower axes 18, 38 is increased and a compressive load is maintained on the ball element precursor 24. The loads, contact patches, and relative movement between the ball element precursor 24/ upper/lower raceways 16, 36 are similar to the mechanics in the ball elements/bail races of a conventional ball bearing.

[0066] Referring to FIG. 8, the geometry of the upper/lower raceways 16, 36 is explained. In one embodiment, the upper raceway profile 20 and lower raceway profile 40 are predetermined elliptical raceway profiles, and in one embodiment comprise the same elliptical shape. The predetermined elliptical raceway profiles maintain optimum raceway conformity at the ball element precursor 24 and final ball diameters for largest possible contact ellipse and wear for the purpose of removing the ball precursor material 26 by lapping or otherwise wearing this material. The predetermined elliptical raceway profiles insure that the contact angle between the ball element precursor 24 and upper/lower raceways 16, 36 never reaches the respective upper/lower raceway shoulders 17, 37. The predetermined elliptical raceway profiles prevent the ball element precursor 24 and/or finished ball element 24’ from contacting or riding on the upper/lower raceway shoulders 17, 37. The raceway conformity of the upper/lower raceways 16, 36 = raceway diameter (e.g. radius of the foci of the ellipse)/ball element precursor 24 diameter. The upper/lower raceway profiles 20, 40 or arc profiles that encompass the ball element precursor 24 are elliptical profiles that accommodate the larger diameter of the unprocessed ball element precursor 24 and maintain the desired contact and predetermine load (L) between the ball element precursor 24 and upper/lower raceways as the ball element precursor 24 is reduced to the final size of the ball element 24’.

[0067] Referring to FIG. 9, an alternate geometry of the upper/lower raceway profiles 20, 40 is described and illustrated. Multiple upper/lower raceway profiles/geometries 20, 40 (any suitable concave curved arc) can also be utilized if the appropriate spacing between the upper/lower machining raceways 16, 36 is maintained and contact between ball element precursor 24 and the upper/lower raceway shoulders 17, 37 is not permitted (the contact angle does not reach the shoulder). For example, simple raceway (single arc (e.g. circular arc)) profiles/geometries can also be designed that may not be as efficient as the raceways 16, 36 with the elliptical profile. Multiple upper/lower raceway profiles/geometries 20, 40 and methods of positioning the raceways can be established as long as the appropriate relationship is maintained between the upper/lower machining raceways 16, 36 and ball element precursors 24 (e.g. contact between ball element precursor 24 and the upper/lower raceway shoulders 17, 37 is not permitted).

[0068] Referring to FIGS. 10, the ball dynamics and velocity at the elliptical contact patches is described and illustrated. As shown in FIG. 10, there is a large upper contact patch or portion 29 and a large lower contact patch or portion, both of which may be elliptical, between the upper/lower raceway profiles 20, 40 of the upper/lower machining raceways 16, 36 and the ball element precursor 24 - the convex interface of the ball element precursor 24 engaging the concave upper/lower raceway profiles 20, 40. The upper machining wheel 12 and upper wheel raceway 16 is rotating at an upper wheel velocity (V2) and the lower machining wheel 32 and lower wheel raceway 36 is rotating at a lower wheel velocity (Vi). As a result of the rotation of upper machining wheel 12 and lower machining wheel 32 and contact of the upper raceway profile 20 and lower raceway profile 40 with upper contact patch 29 and lower contact patch 31, respectively, as well as orbiting of the upper machining wheel 12 and lower machining wheel 32 about one another, the ball element precursor 24 is subject to angular rotation on multiple (e.g. 3) axes to provide or promote even wear and sphericity. There is an angular velocity and rotation due to rolling (cox’), an angular velocity and rotation due to spinning (coy’) and an angular velocity and rotation due to orbiting (coy). The ball element precursor 24 and/or finished ball element 24’ motion and dynamics are complex. An infinite number of rotating speeds and ratios and directions of rotation of the upper machining wheel 16 and lower machining wheel 36 can be created to create different angular velocities of the ball element precursor 24 at the raceway contacts. These rotational dynamics provide very advantageous sliding and wear conditions on the ball element precursor 24 promoting uniform removal of the ball element precursor material 26 and a high degree of sphericity and low degree of waviness of the curved surface of the machined ball elements 24’ upon completion of machining. The orbiting of the upper machining wheel(s)

16 and upper wheel axis (or axes) 18 and lower machining wheel(s) and lower wheel axis (or axes) provide another axis of rotation of the ball element precursor 24 to insure the ball element precursor is rotating on multiple (e.g. 3) axes and that even wear is obtained. Even wear advantageously provides a final ball element 24’ with a high degree of sphericity.

[0069] Referring to FIG. 11, one embodiment of the movement of ball element precursor 24/ball element 24’ and ball dynamics and sliding wear is described and illustrated. The arcuate sliding lines within the upper contact patch 29 and lower contact patch 31 for the condition where Vi > V2 and the directions of rotation are the same is shown in FIG. 11. In this embodiment, the selection of Vi > V2 may be used to create significant sliding and wear. Rolling and spinning are inherent to all rolling motion and the high degree of sliding provide by selecting Vi > V2 may be used to provide a high rate of material removal.

[0070] Referring to FIG. 12, in one embodiment of the movement of ball element precursor 24/ball element 24’ and ball dynamics and ball/sphere rolling is described and illustrated.

The arcuate sliding lines within the upper contact patch 29 and lower contact patch 31 for the condition where Vi = V2 and the directions of rotation are the same is shown in FIG. 12. In this embodiment, the selection of Vi = V2 may be used to process a ball element precursor 24 using a rolling motion and compressive loads. This condition provides an opportunity to process a ball element precursor 24 or blank under the same/similar conditions and compressive loads as found in many rolling bearing applications. The process of manufacturing a ceramic blank (rough ball element precursor shape) powders are compressed with a binder under high temperatures (sintering process). The sintered blank is not very dense and can contain voids that are detrimental to the strength and durability of the product. Further processing steps such as hot isostatic pressing (HIP) comprise placing the blank in a high pressure and temperature oven to further compress and densify the material. This process still may result in material with defects such as voids and folds. Currently expensive and time consuming inspection processes such as Florescent Penetrant Inspection is used to confirm no defects are at the surface of the ball element precursor 24. In bearing operation, rolling contact creates stresses at the ball element precursor surface 24 and these defects are the point of initial ball failure. If the wheels are rotated at the same speed and a limited amount of sliding is established. The process and machine design concept noted herein could also be utilized to provide an improvement over the current HIP processes to roll sintered blanks under very concentrated compressive stresses and at very high temperatures to reduce or eliminate porosity. This processes in which the initial ball element precursor 24 shape (blank) is manufactured under similar conditions/mechanical stresses in which it is to perform may comprise an important process improvement.

[0071] In one embodiment of the centerless ball element machining system 10, the upper ball raceway 16 comprises an upper abrasive material 28 and/or the lower ball raceway 36 comprises a lower abrasive material 48. The upper abrasive material 28 and the lower abrasive material 48 may be the same material, or different materials, and may comprise any suitable abrasive material including those that provide mechanical abrasion and/or chemical or electrochemical abrasion. In one embodiment, the upper abrasive material 28 and the lower abrasive material 48 comprise a ceramic material, including an abrasive ceramic material, such as, for example, diamond, boron carbide (B4C), silicon carbide (SiC), boron nitride (BN (e.g. cubic BN)), carbon-boron nitride (CBN), aluminum oxide (AI2O3), chromium oxide (CrsCk), zirconium oxide, (ZrCk), silicon oxide (Si02), cerium oxide (CeCk), iron oxide (FeiCh), yttrium oxide (Y2O3), copper oxide (CuO), molybdenum oxide (M02O3), or tungsten carbide (WC), or a combination thereof, or a composite thereof. The abrasive ceramic materials may be formed into the articles described herein by any suitable ceramic material fabrication method, such as, for example, various forms of sintering, tape casting and sintering, or hot pressing and sintering, and may comprise fully dense (e.g. the stoichiometric density or > 99.9%), substantially fully dense (e.g. less than fully dense (e.g. 99.9% to 95.)%) due to some porosity), or partially dense (e.g. <95.0%. In this embodiment, the upper ball raceway 16 and/or the lower ball raceway 36 may be formed entirely from the upper abrasive material 28 and/or the lower abrasive material 48, respectively, or the upper abrasive material 28 and/or the lower abrasive material 48 may comprise only a part of the upper ball raceway 16 and/or the lower ball raceway 36, such as by a coating or layer of the upper abrasive material 28 and/or the lower abrasive material 48 applied to a backing substrate, such as a metal substrate such as, for example, a substrate of various alloys of iron, including various grades and alloys of steel (e.g. stainless steel), aluminum, magnesium, or titanium, or combination thereof, or composites thereof. In this embodiment, the upper abrasive material 28 and/or the lower abrasive material 48 may comprise the primary abrasive material and lapping and grinding of the ball element precursors 24 may be performed using a suitable liquid medium as a lubricant. Alternately, the lapping and grinding of the ball element precursors 24 may be performed using a suitable abrasive media 35 comprising abrasive particles disposed in (e.g. as a suspension) a liquid medium, as described herein.

[0072] In another embodiment of the centerless ball element machining system 10, the upper ball raceway 16 comprises an upper non-abrasive material 30 and/or the lower ball raceway 36 comprises a lower non-abrasive material 50. The upper non-abrasive material 30 and the lower non-abrasive material 50 may be the same material, or different materials. In one embodiment, the upper non-abrasive material 30 and the lower non-abrasive material 50 comprise a metal, such as, for example, various alloys of iron, including various grades and alloys of steel (e.g. stainless steel), aluminum, magnesium, or titanium, or combination thereof, or composites thereof. In this embodiment, the lapping and grinding of the ball element precursors 24 may be performed using a suitable abrasive media 35 comprising abrasive particles disposed in (e.g. as a suspension) a liquid medium, as described herein.

[0073] In one embodiment, the upper ball raceway 16 comprising an upper abrasive material 28 or non-abrasive material 30 and/or the lower ball raceway 36 comprising a lower abrasive material 48 or non-abrasive material 50 is/are integrally formed with the upper base 14 and the lower base 34. In another embodiment, the upper ball raceway 16 comprising an upper abrasive material 28 or non-abrasive material 30 and/or the lower ball raceway 36 comprising a lower abrasive material 48 or non-abrasive material 50 is/are formed separately and is/are selectively attachable to and detachable from the upper base 14 and/or the lower base 34, respectively, by any suitable attachment/detachment device, such as, for example, a plurality of threaded fasteners that attach the raceways to the bases, or by forming interlocking features on the upper ball raceway 16 and/or the lower ball raceway 36 that interlock with mating interlocking features of the upper base 14 and the lower base 34, respectively (e.g. a bayonet mount). This selectively attachable and detachable arrangement of the upper ball raceway 16 and/or the lower ball raceway 36 is very advantageous because it allows the raceways to be easily removed, replaced or serviced (e.g. dressing the raceways to maintain a predetermined raceway profile as described herein), and reattached.

[0074] In one embodiment of the centerless ball element machining system 10, the abrasive media 35 comprises a plurality of abrasive particles dispersed in a liquid medium or a fluid medium. In one embodiment, the abrasive particles comprise a ceramic material, including an abrasive ceramic material, such as, for example, diamond, boron carbide (B 4 C), silicon carbide (SiC), boron nitride (BN (e.g. cubic BN)), carbon boron nitride (CBN), aluminum oxide (AI2O3), chromium oxide (CNCh), zirconium oxide, (ZrC^), silicon oxide (Si02), cerium oxide (CeCh), iron oxide (FeiCb), yttrium oxide (Y2O3), copper oxide (CuO), molybdenum oxide (M02O3), or tungsten carbide (WC), or a combination thereof, or a composite thereof, and the liquid medium comprises water, water-based or aqueous liquids or fluids of any form (e.g. various solutions, complexes, suspensions, and the like), or an oil, including all manner of organic or inorganic oils. The abrasive media 35 comprising the abrasive particles and the liquid medium or fluid medium may have any suitable fluid form or characteristic, including any suitable viscosity and/or rheology (e.g. various suspensions, sols, gels, pastes, and the like). The plurality of abrasive particles may have any suitable particle size, particle morphology (e.g. fully dense or porous), and particle shape.

[0075] Referring to FIGS. 1-6, for example, in one embodiment, the centerless ball element machining system 10 further comprises a stop member 138 that is configured to limit a translation of the upper wheel axis 18 and the upper machining wheel 12 as the ball element material is removed during machining of the ball element precursor 24 and a lower stop 139 that is configured to limit a translation of the lower wheel axis 38 and the lower machining wheel 32.

[0076] Referring to FIGS. 1-6, and 14, for example, in one embodiment, the centerless ball element machining system 10 is configured to process a single ball element precursor 24. [0077] Referring to FIG. 15, in one embodiment the centerless ball element machining system 10 is also configured to process a plurality of ball element precursors 241, 24-2, and so on simultaneously. This centerless ball element machining system 10 comprises an upper machining wheel 12 comprising a plurality of concentric upper machining wheels 12-1, 12-2 and so on stacked on one another and configured to rotate together. The lower machining wheel 32 comprises a corresponding plurality of concentric lower machining wheels 32-1, 32-2, and so on stacked on one another and configured to rotate together, and the plurality of corresponding plurality of upper raceway profiles 20-1, 20-2, and so on and the plurality lower raceway profiles 40-1, 40-2, and so on are configured to receive a corresponding plurality of the ball element precursors 24-1, 24-2, and so on. This configuration is very advantageous because it can be used to process a plurality of ball element precursors simultaneously on the same machine.

[0078] Referring to FIG. 16, in one embodiment the centerless ball element machining system 10 is also configured to process a plurality of ball element precursors 24-1, 24-2, and so on simultaneously. This centerless ball element machining system 10 comprises an upper machining wheel 12 comprising a plurality of concentric cylindrical upper ball raceways 16 comprising a plurality of concentric circumferentially-extending concave upper raceway profiles 20 on respective inner surfaces 22. The upper raceway profiles 20 are configured to receive a corresponding plurality of the ball element precursors 24. The lower machining wheel 32 comprises a plurality of concentric cylindrical lower ball raceways 36 comprising a plurality of concentric circumferentially-extending concave lower raceway profiles 40 on respective inner surfaces 42, the lower raceway profiles are also configured to receive the corresponding plurality of the ball element precursors 24. This configuration is also very advantageous because it can be used to process a plurality of ball element precursors simultaneously on the same machine.

[0079] Referring to FIGS. 17A and 17B, in one embodiment the centerless ball element machining system 10 is also configured to process a plurality of ball element precursors 24 simultaneously. This centerless ball element machining system 10 comprises an upper machining wheel 12 that comprises a single upper machining wheel that is configured to be rotatably disposed on an upper wheel axis 18, and the lower machining wheel 32 comprises a plurality of radially and circumferentially spaced lower machining wheels that are configured to be rotatably disposed on a corresponding plurality of lower axes 38, the upper raceway profile 16 and plurality of lower raceway profiles 36 configured to receive a corresponding plurality of the ball element precursors 24. In this embodiment, the single upper machining wheel 12 may have a smaller diameter than the lower machining wheels 32 and is configured to be centrally rotatably disposed on an upper wheel axis 18 in the midst of the lower machining wheels 32 and lower axes 38. In one embodiment, the lower wheels are circumferentially spaced at equal angles about the upper wheel axis 18. Any suitable number of lower machining wheels may be used, including 2-10, more particularly 2-6, and more particularly 2-4 lower machining wheels. In one embodiment, the lower machining wheels 32 may be gear driven using an epicyclic gear or ring gear 68 and a plurality of lower planetary gears 78 corresponding in number to and attached to the lower machining wheels 32 as described herein, and the upper machining wheel 12 may be gear driven by a sun gear 70 that is configured for toothed engagement with and to be driven by the lower planetary gears 78. The ball element precursors 24 may be loaded by insertion through the radially spaced circular openings or holes 54’. A torsion spring 96 in combination with the clutch 94 and motor 60 biases the ball element precursors 24 and the lower machining wheels 32 and lower raceways 36 against the upper machining wheels 12 and upper raceway 16 as described herein. This configuration is also very advantageous because it can be used to process a plurality of ball element precursors simultaneously on the same machine.

[0080] Referring to FIG. 13, another embodiment of a centerless ball element machining system 10 is disclosed. This embodiment does not employ a carrier assembly, but rather provides for direct drive of each of the upper machining wheel 12 and the lower machining wheel 32 using a machining center 150, such as a computer numerically controlled (CNC) machining center 150. The machining center 150 comprises a first translation table 152 that is selectively and controllably movable in at least three directions, such as, for example, the x direction, y direction and z direction. The first or lower translation table 152 that comprises a first or lower rotatable spindle 154 rotatable on a first or lower axis 156. The rotational speed and torque of the first rotatable spindle 154 may be controlled by machining center 150. The lower machining wheel 32 is selectively attachable to and detachable from the first rotatable spindle 154. The machining center 150 also comprises a second translation table 158 that is selectively and controllably movable in at least three directions, such as, for example, the x direction, y direction and z direction. The second translation table 158 comprises a second rotatable spindle 160 rotatable on a second axis 162. The rotational speed and torque of the second rotatable spindle 160 may also be controlled by machining center 150. The upper machining wheel 12 is selectively attachable to and detachable from the second rotatable spindle 160. In one embodiment, the first translation table 152 comprising the first rotatable spindle 154 and first axis 156 and the second translation table 158 comprising the second rotatable spindle 160 and second axis 162 are also rotatable about a third or orbiting axis 164. The third axis may be disposed anywhere between the first axis 156 and the second axis 162, including being disposed in the middle, equidistant from both the first axis and the second axis. The rotation of the first machining wheel 12 and the second machining wheel 32 about their respective axes, as well as the rotation or orbiting of the first machining wheel 12 and the second machining wheel about the third axis 164 is similar to the motion provided by the carrier assembly described herein. The upper machining wheel 12 and the lower machining wheel 32 are configured to receive a ball element precursor 24 as described herein. The upper machining wheel 12 and the lower machining wheel 32 are also configured to provide a predetermined bias or load (L) on the ball element precursor 24 and machine the ball element precursor 24 in the same manner as described above for the other embodiment of the centerless ball element machining system 10. The bias or load may be maintained at a constant predetermined load as a function of machining time and as material is removed from the ball element precursor 24, or the bias or load may be reduced at a controlled rate as a function of machining time and as material is removed from the ball element precursor 24. The centerless ball element machining system 10 of this embodiment may be configured with all of the embodiments of the upper machining wheels 12 and upper raceways 16 and the lower machining wheels 32 and lower raceways 36 described herein, including those illustrated in FIGS. 14-17B, for example.

[0081] The centerless ball element machining systems 10 disclosed herein are very advantageous because they reduce the processing time needed to form ball elements 24’ from ball element precursors 24, particularly ceramic ball element precursors, such as those formed from silicon nitride. The current lapping processes for large 2 inch diameter balls is approximately (15) minutes, whereas typical centerless grinding cycle times would take approximately (1) minute per ball. In addition, centerless ball element machining systems 10 provide approximately 40% larger area of the ball element precursor 24 covered by the contact ellipse. The centerless ball element machining systems 10 provide sliding friction of significantly higher magnitudes than current lapping methods, and increased sliding friction promotes greater material removal rates than those offered by prior art lapping systems and lapping methods.

[0082] Referring to the FIGS. 1-17B, a centerless ball element machining wheel 12, 32 is disclosed which may comprise an upper machining wheel 12 or a lower machining wheel 32 and their constituent parts or elements, as described herein.

[0083] The centerless ball element machining wheel 12, 32 comprises a cylindrical base 14, 34 and a cylindrical ball raceway 16, 36. The cylindrical base 14, 34 comprises a wheel axis 18, 38, the cylindrical raceway comprising a circumferentially-extending concave raceway profile 20, 40 on an inner surface 22, 42. The raceway profile 20, 40 is configured to receive a ball element precursor 24 comprising a ball element precursor material 26. The machining wheel 12, 32 is configured to be rotatably disposed on the wheel axis 18, 38. The cylindrical ball raceway 16, 36 comprises an abrasive material 48 and/or a non-abrasive material 50 configured to contain an abrasive media 35 while the machining wheel 12, 32 is rotated. The centerless upper ball element upper machining wheel 12 and lower ball element upper machining wheel 32 and their constituent elements, as described herein, may be the same or different.

[0084] In one embodiment of the centerless ball machining wheel 12, 32, the respective cylindrical ball raceway 16, 36 is selectively attachable and detachable and is configured for periodic removal and replacement or repair.

[0085] Referring to FIG. 16, in one embodiment of the centerless ball machining wheel 12, 32, the upper machining wheel 12 comprises a plurality of concentric cylindrical upper ball raceways 16 comprising a plurality of concentric circumferentially-extending concave upper raceway profiles 20 on the inner surfaces 22. The upper raceway profiles 20 are configured to receive a corresponding plurality of the ball element precursors 24. The lower machining wheel 32 comprises a plurality of concentric cylindrical lower ball raceways 36 comprising a plurality of concentric circumferentially-extending concave lower raceway profiles 40 on the lower inner surface 42. The lower raceway profiles 40 are configured to receive the corresponding plurality of the ball element precursors 24. The plurality of concentric circumferentially-extending concave upper raceway profiles 20 and the plurality of concentric circumferentially-extending concave lower raceway profiles 40 are spaced apart from one another along rays 7, 9 extending outwardly away from the respective centers 13,

33 of the upper machining wheel 12 and the lower machining wheel 32.

[0086] In one embodiment of the centerless ball element machining wheel 12, 32, the base 14, 34 comprises a metal, ceramic, engineering plastic, or a combination thereof.

[0087] In one embodiment, the upper abrasive material and/or the lower abrasive material comprise a ceramic material, including an abrasive ceramic material, such as, for example, diamond, boron carbide (B 4 C), silicon carbide (SiC), boron nitride (BN (e.g. cubic BN)), carbon boron nitride (CBN), aluminum oxide (AI2O3), chromium oxide (CNCh), zirconium oxide, (ZrCh), silicon oxide (Si02), cerium oxide (CeC ), iron oxide (FeiCb), yttrium oxide (Y2O3), copper oxide (CuO), molybdenum oxide (M02O3), or tungsten carbide (WC), or a combination thereof, or a composite thereof.

[0088] In one embodiment of the centerless ball element machining wheel 12, 32 the abrasive media 35 comprises a plurality of abrasive particles dispersed in a liquid medium or fluid medium as described herein. In one embodiment, the abrasive particles comprise a ceramic material, including an abrasive ceramic material, such as, for example, diamond, boron carbide (B 4 C), silicon carbide (SiC), boron nitride (BN (e.g. cubic BN)), carbon boron nitride (CBN), aluminum oxide (AI2O3), chromium oxide (CnC ), zirconium oxide, (ZrCh), silicon oxide (Si02), cerium oxide (CeCh), iron oxide I^Cb), yttrium oxide (Y2O3), copper oxide (CuO), molybdenum oxide (M02O3), or tungsten carbide (WC), or a combination thereof, or a composite thereof, and the liquid medium or fluid medium comprises water, water-based or aqueous liquids or fluids of any form (e.g. various solutions, complexes, suspensions, and the like), or an oil, including all manner of organic or inorganic oils. The abrasive media 35 comprising the abrasive particles and the liquid medium or fluid medium may have any suitable liquid or fluid form or characteristic, including any suitable viscosity and/or rheology (e.g. various suspensions, sols, gels, pastes, and the like). The plurality of abrasive particles may have any suitable particle size, particle morphology (e.g. fully dense or porous), and particle shape.

[0089] In one embodiment, the centerless ball element machining wheel 12, 32 is configured to receive a ball element precursor material 24 that comprises a ceramic. In one embodiment, the ceramic of the ball precursor material 24 comprises silicon nitride. [0090] Referring to FIG. 18, in one embodiment, a method 200 of making a centerless ball element machining system 10 is disclosed.

[0091] The method 200 of making the centerless ball element machining system 10 comprises forming 210 an upper machining wheel comprising a cylindrical upper base and a cylindrical upper ball raceway, the cylindrical upper base comprising an upper wheel axis, the cylindrical upper ball raceway comprising a circumferentially-extending concave upper raceway profile on an inner surface, the upper raceway profile configured to receive a ball element precursor comprising a ball element material, the upper machining wheel configured to be rotatably disposed on the upper wheel axis, the cylindrical upper ball raceway comprising an upper abrasive material and/or comprising a non-abrasive material and configured to contain an abrasive media 35 while the upper machining wheel is rotated; a lower machining wheel comprising a cylindrical lower base and a cylindrical lower ball raceway, the cylindrical lower base comprising a lower wheel axis, the cylindrical lower ball raceway comprising a circumferentially-extending concave lower raceway profile on an inner surface, the lower raceway profile configured to receive a ball element precursor, the lower machining wheel configured to be rotatably disposed on the lower wheel axis, the cylindrical lower ball raceway comprising a lower abrasive material and/or comprising a non-abrasive material and configured to contain the abrasive media 35 while the lower machining wheel is rotated, the upper raceway profile disposed above the lower raceway profile with the upper raceway profile facing the lower raceway profile, the upper wheel axis spaced apart from the lower wheel axis by a predetermined distance selected to capture the ball element precursor between the upper raceway profile and the lower raceway profile; and a bias member, the bias member operatively coupled to at least one of the upper machining wheel or the lower machining wheel configured to provide a predetermined load on the ball element precursor from the upper machining wheel and the lower machining wheel, the upper machining wheel and lower machining wheel configured to remove the ball element material upon rotation about the upper wheel axis and lower wheel axis, respectively, in the presence the abrasive media 35, the upper raceway profile and lower raceway profile selected to increase the sphericity of the ball element precursor upon removal of the ball element material.

[0092] The method 200 of making a centerless ball element machining system 10 also comprises forming 220 a drive assembly 56 as described herein. [0093] The method 200 of making a centerless ball element machining system 10 also comprises forming 230 a carrier assembly 80 as described herein.

[0094] The method 200 of making a centerless ball element machining system 10 also comprises attaching 240 the upper machining wheel 12, lower machining wheel 32, and bias member 52 to the carrier assembly 80 as described herein.

[0095] The method 200 of making a centerless ball element machining system 10 also comprises attaching the upper machining wheel 12, lower machining wheel 32, bias member and carrier assembly 80 to the drive assembly 56 as described herein.

[0096] Referring to FIG. 19, in one embodiment, a method 300 of using a centerless ball element machining system 10 as described herein is disclosed.

[0097] The method 300 of using a centerless ball element machining system 10 comprises forming 310 a centerless ball element machining system 10 comprising: an upper machining wheel comprising a cylindrical upper base and a cylindrical upper ball raceway, the cylindrical upper base comprising an upper wheel axis, the cylindrical upper ball raceway comprising a circumferentially-extending concave upper raceway profile on an inner surface, the upper raceway profile configured to receive a ball element precursor comprising a ball element material, the upper machining wheel configured to be rotatably disposed on the upper wheel axis, the cylindrical upper ball raceway comprising an upper abrasive material and/or comprising a non-abrasive material and configured to contain an abrasive media 35 while the upper machining wheel is rotated; a lower machining wheel comprising a cylindrical lower base and a cylindrical lower ball raceway, the cylindrical lower base comprising a lower wheel axis, the cylindrical lower ball raceway comprising a circumferentially-extending concave lower raceway profile on an inner surface, the lower raceway profile configured to receive a ball element precursor, the lower machining wheel configured to be rotatably disposed on the lower wheel axis, the cylindrical lower ball raceway comprising a lower abrasive material and/or comprising a non-abrasive material and configured to contain the abrasive media 35 while the lower machining wheel is rotated, the upper raceway profile disposed above the lower raceway profile with the upper raceway profile facing the lower raceway profile, the upper wheel axis spaced apart from the lower wheel axis by a predetermined distance selected to capture the ball element precursor between the upper raceway profile and the lower raceway profile; a bias member, the bias member operatively coupled to at least one of the upper machining wheel or the lower machining wheel configured to provide a predetermined load on the ball element precursor from the upper machining wheel and the lower machining wheel, the upper machining wheel and lower machining wheel configured to remove the ball element material upon rotation about the upper wheel axis and lower wheel axis, respectively, in the presence the abrasive media 35, the upper raceway profile and lower raceway profile selected to increase the sphericity of the ball element precursor upon removal of the ball element material; a carrier assembly comprising an upper carrier plate and a lower carrier plate configured to rotatably carry the upper machining wheel and lower machining wheel and house the bias member; and a drive assembly comprising an electric motor and a rotatable motor shaft that is configured to rotate the carrier assembly carrier assembly and bias the bias member.

[0098] The method 300 of using a centerless ball element machining system 10 also comprises disposing 320 the ball element precursor between the upper raceway profile and the lower raceway profile. This can be accomplished as described herein and illustrated in FIG. 5.

[0099] The method 300 of using a centerless ball element machining system 10 also comprises disposing 330 a lubricant and/or an abrasive media 35 in contact with the ball element precursor.

[00100] The method 300 of using a centerless ball element machining system 10 also comprises operating 340 the electric motor to rotate the upper machining wheel and the lower machining wheel thereby removing the ball element material from the ball element precursor. [00101] The method 300 of using a centerless ball element machining system 10 also comprises stopping 350 the electric motor and removing the ball element precursor when the ball element precursor comprises a predetermined size, a predetermined sphericity, or a predetermined surface finish, or a combination thereof, to define a ball element 24’. In one embodiment, the method 300 of using the centerless ball element machining system 10 also comprises optionally measuring 392 the ball element precursor and adjusting the positions of the machining wheels prior to additional machining of additional precursor ball elements 24. [00102] In one embodiment, the method 300 of using the centerless ball element machining system 10 further comprises checking 360 the upper raceway profile and/or the lower raceway profile for a predetermined wear characteristic; and if a predetermined wear characteristic is indicated , removing 370 the upper ball raceway and/or the lower ball raceway having the predetermined wear characteristic; and replacing 380 the upper ball raceway and/or the lower ball raceway with the upper raceway profile and/or the lower raceway profile by replacing or repairing the respective raceway; and continuing 390 to operate the electric motor and dispensing a flow of the lubricant and/or the abrasive media into contact with the ball element precursor while operating the electric motor, which optionally may be followed by measuring 392 the ball element precursor and adjusting the positions of the machining wheels prior to additional machining of additional precursor ball elements 24.

[00103] In one embodiment, the centerless ball element machining system 10 further comprises a dispenser 170 for dispensing a flow 172 of the lubricant 31 and/or the abrasive media 35, particularly the liquid medium, onto the ball element precursors 24 and the upper raceway(s) 16 and lower raceway(s) 36 during grinding and/or lapping that is installed as part of the method of making 200. The method of using further comprises dispensing 390 a flow 172 of the lubricant 31 and/or the abrasive media 35into contact with the ball element precursor while operating the electric motor 60. The abrasive media 35, particularly the liquid medium, may be selected to act as a lubricant and/or as a coolant to cool the ball element precursors 24 and the upper raceway(s) 16 and lower raceway(s) 36 during grinding and/or lapping.

[00104] In one embodiment, the centerless ball element machining system 10 further comprises upper position sensor 180 disposed on the upper machining wheel 12 or the upper carrier plate 102 and lower position sensor 182 disposed on the lower machining wheel 32 or the lower carrier plate 82, and in signal communication with the controller 62, that are configured to sense and in conjunction with the controller 62 determine the positions of the upper machining wheel 12 and the lower machining wheel 32, which are installed as part of the method of making 200. The method of using 300 may also comprise measuring 392 the ball element precursor 24 diameter automatically to determine the ball size and, using a feedback loop based on the positions determined by the upper position sensor 180 and lower position sensor 182, and adjusting the positions of the upper machining wheel 12 and lower machining wheel 32 to provide and apply a predetermined amount of bias or load to the ball element precursors 24 to achieve the next predetermined ball size. [00105] In one embodiment, the centerless ball element machining system 10 further comprises an automatic feeding and/or removal system 184 to feed new ball element precursors 24 between the upper raceway 16 and lower raceway 36 and/or to remove ball elements 24’ as they are machined to achieve the predetermined ball size. In one embodiment, the automatic feeding and/or removal system 184 comprises a robotic ball pick and place machine 186 that is in signal communication with and configured for control by the controller 62 to pick and remove a finished ball element 24’ and then pick and insert a new ball element precursor 24 for machining as described herein.

[00106] The terms "a" and "an" herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., includes the degree of error associated with measurement of the particular quantity). Furthermore, unless otherwise limited all ranges disclosed herein are inclusive and combinable (e.g., ranges of “up to about 25 weight percent (wt.%), more particularly about 5 wt.% to about 20 wt.% and even more particularly about 10 wt.% to about 15 wt.%” are inclusive of the endpoints and all intermediate values of the ranges, e.g., “about 5 wt.% to about 25 wt.%, about 5 wt.% to about 15 wt.%”, etc.). The use of “about” in conjunction with a listing of items is applied to all of the listed items, and in conjunction with a range to both endpoints of the range. Finally, unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this invention belongs. The suffix “(s)” as used herein is intended to include both the singular and the plural of the term that it modifies, thereby including one or more of that term (e.g., the metal(s) includes one or more metals). Reference throughout the specification to “one embodiment”, “another embodiment”, “an embodiment”, and so forth, means that a particular element (e.g., feature, structure, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments.

[00107] It is to be understood that the use of “comprising” in conjunction with the components or elements described herein specifically discloses and includes the embodiments that "consist essentially of’ the named components (i.e., contain the named components and no other components that significantly adversely affect the basic and novel features disclosed), and embodiments that "consist of' the named components (i.e., contain only the named components).

[00108] While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.