[0001] The present patent document claims benefit of the filing under 35 U.S.C.

§119(e) of U.S. provisional application no. 62/047,434, filed September 8, 2014, which is hereby incorporated by reference.

BACKGROUND

1. Field of the Invention

[0002] The present invention generally relates to a gage for thrufeed centerless grinding. Such gages are ones in which workpieces exiting the grinder are measured without the necessity of fixturing the workpiece during gaging. More specifically, the invention relates to a thrufeed gage having top guide for the workpieces.

2. Description of Related Technology

[0003] Thrufeed feed centerless grinding is used for the high volume precision grinding of the outside diameters of a variety of parts. Such parts include, without limitation, electric motor shafts, gas spring rods, shock absorber rods, transmission shafts, and ball studs. One advantage of such machines is the automatic flow of workpieces through the machine, as if one long workpiece is being ground.

[0004] During grinding, the workpiece is supported by a grinding wheel, regulating wheel and a work rest blade. Due to the machine elements that support the workpiece, it is difficult to provide a gage at a location that will measure the finished part size while it is between the regulating and grinding wheels. As a result, most centerless grinding gages are post process gages. In other words, the workpieces are gaged after they have left the grinder. While some post process gages confine the workpiece in a fixture during measurement, a thrufeed centerless grinder does not confine the workpiece, but instead continuously moves the workpieces through the gage while they are being measured. Since the accuracy of the gaging process can be seriously compromised by the moving of the workpieces, the workpieces must be stabilized relative to the gage in order to attain accurate gage readings.

SUMMARY

[0005] In an aspect of the invention, an apparatus is provided for measuring cylindrical workpieces having circular, generally uniform, cross sections, as the workpieces exit a grinding machine. The apparatus comprises a gage having a pair of contacts for engagement with opposite sides of the workpieces and which is configured to measure the diameter of the workpieces. The gage is mounted relative to a first conveyor such that the contacts engage each workpiece on opposite sides of the workpieces. The first conveyor includes a first frame and a first endless belt supported and carried by the first frame and upon which the workpieces are supported. The first conveyor further includes a guide rail cooperating with the first endless belt to define the path of travel. A second conveyor includes a second frame and a second endless belt supported and carried by the second frame. The second conveyor is located opposite of the first conveyor with the predetermined path of travel passing between the first and second conveyor. When a workpiece is positioned between the first conveyor and the second conveyor, the gage measures the diameter of the workpiece.

[0006] In another aspect, the second conveyor is located opposite of the guide rail.

[0007] In a further aspect, the contacts of the gage are positioned to measure the diameter of the workpiece when the workpiece is supported by the guide rail and located between the guide rail and the second endless belt of the second conveyor.

[0008] In an additional aspect, the workpieces are conveyed over the guide rail solely by the second endless belt.

[0009] In still another aspect, the guide rail is bounded on opposing ends by the first endless belt.

[0010] In yet a further aspect, the guide rail include tapered ends.

[0011] In an additional aspect, the tapered ends of the guide rail correspond to a radius of curvature.

[0012] In a further aspect, the radius of curvature corresponds to a radius of curvature exhibited by the first endless belt immediately adjacent to the guide rail.

[0013] In yet another aspect, the first conveyor and the second conveyor are each driven by a motor.

[0014] In an additional aspect, the first conveyor and the second conveyor are each driven by a common motor.

[0015] In still a further aspect, the common motor is configured to drive first conveyor and the second conveyor at the same speed.

[0016] In another aspect, the first conveyor and the second conveyor coupled to the common motor by a synchronous gear set.

[0017] In an additional aspect, a portion of the second endless belt is located in a position directly opposing the guide rail and is oriented parallel to the guide rail. [0018] In still another aspect, the guide rail is mounted in a support block that is adjustably secured to the second conveyor.

[0019] In a further aspect, the second conveyor is vertically adjustable relative to the first conveyor to enable the apparatus to accommodate workpieces of different sizes.

[0020] In yet an additional aspect, the first endless belt is configured as a pair of endless belts.

[0021] In still a further aspect, the second endless belt is configured as a single belt.

[0022] In another aspect, the guide rail is configured as a pair of guide rails.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a perspective view of a thrufeed gaging station embodying the principles of the present invention;

[0024] Figure 2 is an enlarged view of a portion, the thrufeed gage assembly, of the thrufeed gaging station seen in Figure 1 ;

[0025] Figure 3 is a rear perspective view of the thrufeed gage assembly seen in

Figure 2;

[0026] Figure 4 is a front elevational view of the thrufeed gage assembly seen in

Figures 2 and 3;

[0027] Figure 5 is a front elevational view, similar to Figure 4, of the thrufeed gage assembly with various front covers removed and showing internal components of the assembly;

[0028] Figure 6 A and 6B are similar to Figure 5, but are perspective views of the thrufeed gage assembly, with the front covers removed and revealing the various internal components of the assembly;

[0029] Figure 7 is a cross sectional view of an alternative construction for the guide belt; and

[0030] Figure 8 is a further alternative construction for the guide belt.

DETAILED DESCRIPTION

[0031] As a preliminary note, the terms "about," "generally," "substantially," and

"approximately," as used herein, are intended to mean within the corresponding manufacturing, equipment, product or production process tolerances as would be appreciated by those skilled in the technology. [0032] Referring now to the drawings, a thrufeed gaging station, embodying the principles of the present invention, is illustrated in Figure 1 and designated at 10. As its primary components, the thrufeed gaging station 10 includes a stand or frame 12, upon which a thrufeed gage assembly 14 is supported. The stand 12 may be movable and included legs 16 supported by lockable casters 18 and/or lockable floor supports 20. The stand 12 includes an upper portion 22, which carries the thrufeed gage assembly 14, that may be movable relative to the stand 12 for adjustment purposes. In one variation, this adjustability can be accomplished by mounting the thrufeed gage assembly 14 to the stand 12 utilizing a linear slide 24.

[0033] The thrufeed gage assembly 14, as seen in Figures 1 and 2, includes a number of main components. Those main components include, without being bound with respect to the criticality of any individual component, a main or lower conveyor 26, a top conveyor or guide 28, a gage 30, an actuator 32, a diverter 34 and a controller or control panel 36.

[0034] The main or lower conveyor 26 (hereinafter just "conveyor 26") receives cylindrical workpieces 38 (seen in Figures 1, 3, 5 and 6) from a centerless grinding machine (not shown) in a substantially continuous manner such that the workpieces 38 are fed to the conveyor 26 one after another. The workpieces 38 are received by transfer guides 40 onto the conveyor 26 and then conveyed along a path of travel, defined by the conveyor 26, and through a location where the workpieces 38 pass between the conveyor 26 and the top conveyor or guide 28 (hereinafter just "guide 28"). While between the conveyor 26 and the guide 20, the workpieces 38 are measured by the gage 30. Those workpieces 38 deemed unacceptable after being measured by the gage 30 are caused to be rejected by the diverter 34, which operates to laterally displace the unacceptable workpieces 38 into a catch pan 42. Acceptable workpieces 38 are discharged from the conveyor 26

[0035] Referring now specifically to the conveyor 26, the conveyor 26 includes a housing 44, defined by a pair of sidewalls or covers 46, within which a pair of endless belts 48 are disposed. Along the upper surface of the conveyor 26, the belts 48 are exposed so that they may receive the workpieces 38 from the centerless grinder at one end of the conveyor 26 and discharge the measured and acceptable workpieces 38 at the other end. However, the endless belts 48 do not traverse along the entire upper surface of the conveyor 26. Rather, the endless belts 48 are configured so that, at an intermediate position along the upper surface of the conveyor 26, the endless belts 48 are routed internally the housing 44. This intermediate position is generally located opposite of the guide 28. Instead of the endless belts 48 traversing this intermediate position opposite of the guide 28, the conveyor 26 includes a pair of stationary guide rails 50 having tapered ends 52.

[0036] As further illustrated in Figures 5, 6A and 6B, the endless belts 48 are wound about a series of pulleys 54. While the style, number and location of pulleys may vary depending on the particular application and construction of the conveyor 26, in the illustrated variant, the pulleys are dual pulleys, meaning that they contain two adjacent grooves for receiving the pair of endless belts 48 in a side -by-side arrangement. At opposing ends of the conveyor 26, intake and outtake end pulleys 56, 66 are provided to route the endless belts 48 in an exposed manner along the upper surface of the conveyor 26. Proceeding from an intake end 57 of the conveyor 26, where the workpieces 38 are received, the endless belts 48 progress along the upper surface of the conveyor 29 until encountering a first or leading intermediate pulley 58, which is located adjacent to one of the tapered ends 52 of the guide rails 50. The leading intermediate pulley 58 then routes the endless belts 48 inward of the housing 44 and away from the upper surface. From the leading intermediate pulley 58, the endless belts 48 are generally routed back toward the intake end 57 of the conveyor 26. Prior to reaching the intake end 57 of the conveyor 26, the endless belts 58 encounter a first direction reversing pulley 60. The first direction reversing pulley 60 redirects the endless belts 58 approximately 180°, generally toward the outtake end 61 to the conveyor 26. The endless belts 58 next engage a second direction reversing pulley 62, which also redirects the endless belts 58 approximately 180°. At this point, the endless belts 58 are being directed generally toward the intake end 57 of the conveyor 26. After the second direction reversing pulley 62, the endless belts 58 encounter a trailing intermediate pulley 64. The trailing intermediate pulley 64 re-directs the endless belts 58 back to the upper surface of the conveyor 26, adjacent to the other tapered ends 52 of the guide rails 50, where they are again exposed along the upper surface of the conveyor 26. At this location, the endless belts 40 receive workpieces 38 from the guide rails 50 after they have been measured. The endless belts 48 thereafter proceed along the upper surface of the conveyor 26 until reaching the outtake end 61 of the conveyor 26, where the endless belts 48 encounter an outtake end pulley 66. The outtake end pulley 66 re-routes the endless belts 58 back into the housing 44 and back towards the first end pulley 56 located at the intake end 57 of the conveyor 26. For this re-routing purpose, additional pulleys, such as spacer pulley 68 may be used to space the endless belts 48 apart from the previously mentioned pulleys and location of the belts 48 within the housing 44. [0037] Additionally, at least one of the pulleys is coupled to a tensioning mechanism

70 allowing for the tension of the endless belts 40 to be adjusted. The tensioning mechanism maybe any one of the well-known mechanisms for this purpose. As illustrated, a threaded rod 72 is coupled to the second direction reversing pulley 62. The threaded rod 72, along with the pulley 62, is movable to adjust the tension in the endless belts 48. Translational movement of the threaded rod 72, and therefore the pulley 62, is achieved by extending the rod 72 through a fixation block 74, connected to the side cover, and rotation of an adjustment nut 76. A locking nut 78 may be used to finally secure pulley 62 once the desired tension has been achieved.

[0038] Preferably, the endless belts 58 of the conveyor 26 are formed of reinforced urethane and have a nylon or Kevlar core.

[0039] In the locations where the endless belts 58 are exposed along the upper surface of the conveyor 26, the endless belts 58 are positioned relative to the guide rails 50 such that the workpieces 38 are transferred from the endless belts 58 to the guide rails 50 in a seamless fashion and without any significant change in the vertical positioning of the workpieces 38 relative to the thrufeed gage assembly 14. Such that the uppermost surfaces of the endless belts 58 are preferably parallel to and coplanar with the uppermost surface of the guide rails 50.

[0040] The guide rails 50 are preferably round rods formed of carbide, titanium coated carbide, ceramic or other materials that are non-wearing or that have a non-wearing coating thereon, such as steel or carbide rods having a ceramic spray coating or flamed-on coating. The tapered ends 52 of the guide rails 50 are such that the endless belts 48 smoothly transition to the guide rails 50 without a significant gap. By minimizing the gap at the transition between the endless belts 48 and the guide rails 50, the likelihood of an end of a workpiece 38 catching and become caught on the ends 52 of the guide rails 50 is minimized.

[0041] In one preferred embodiment, the guide rails 50 have a length that is at least twice the length of the workpieces 38 handled by the gaging station 10. Regarding the tapered ends 52, preferably the taper exhibited by these ends 52 corresponds to the radius of curvature of the endless belts 48 as they extend around the leading and trailing intermediate pulleys 58 and 64. Additionally, the guide rails 50 are adhesively mounted in a support block 80. The support block 80 is adjustably secured within the conveyor 26, preferably to the side cover 46, which operates to support the pulleys and tensioning mechanism 70 discussed above. The adjustability of the support block 80 provides sufficient adjustment for the guide rails 50 relative to the adjacent sections of the endless belts 48, as well as for easy replacement of the guide rails 50 if necessary.

[0042] The guide 28 includes a housing 82 within which an endless guide belt 84 is provided and circulated. The housing 82 further includes a pair of side covers 86, which are shown in their operating positions in Figures 1-4. In Figures 5-6B, the guide 28 is shown with one of the side covers removed, revealing the internal components of the guide 28.

[0043] The guide 28 is positioned relative to the conveyor 26 such that the guide 28, and in particular the guide belt 84, is opposite of the guide rails 50. Guide 28 and guide belt 84 are also located opposite of portions of the endless belts 48, the latter occurring at least in the regions where the endless belts 48 traverse the leading and trailing intermediate pulleys 58 and 64.

[0044] The guide belt 84 extends around a set of pulleys, which in the illustrated embodiment includes a drive pulley 86, coupled to the motor 32, and return pulley 88, each located at one end of the guide 28. The drive pulley 86 is preferably located on the same general side of the thrufeed gage assembly 14 as the pulley operating as the drive pulley of the conveyor 26. No pulley of the conveyor 26 was previously indicated as being the drive pulley for the conveyor 26. However, in the illustrated embodiment, the first direction reversing pulley 60 has this function and is coupled to the motor 32.

[0045] In coupling the drive pulleys (drive pulley 86 and the first direction reversing pulley 60) to the motor 32, a synchronizing gear set 89 connects the output of the motor 32 to these pulleys. The synchronizing gear set 89 induces a rotation speed in each of the drive pulleys that results in their corresponding belts, endless belts 48 and guide belt 84, being circulated at the same speed. This is important to ensure smooth movement of the workpieces through the thrufeed gage assembly 14 because, at times, both belts will be simultaneously in engagement with the workpieces 38.

[0046] To adjust the tension in the guide belt 84, the guide 28 includes an idler pulley

90 whose position relative to the guide belt 84 can be adjusted via the tension mechanism 92. The tension mechanism 92 generally operates along the same principles as the previously discussed tension mechanism and is not further discussed herein.

[0047] The guide belt 84 is preferably constructed configured as a non-reinforced urethane V-belt having a predetermined amount of compliancy or give in compression. This give in compression allows the guide belt 84 to isolate the individual workpieces 38 from one another as they are engaged by the guide belt 84. Alternatively, the guide belt 84 may be a reinforced V-belt. [0048] Where the guide belt 84 is directly opposite of the guide rails 50, the guide belt additionally rides along a backer 94. The backer 94 is carried within a support block 96 that is adjustably mounted to the guide 28 and, more preferably to the side cover 85 that supports the drive and return pulleys 86 and 88. The backer 94 is preferably constructed of a hard, non-wearing material such as that described for the guide rails 50. Alternatively, the backer 94 can be constructed of a urethane material that allows the guide belt 84 to glide there over. Adjustability of the positioning of the support block 96 is sufficient to enable the backer 94, and therefore the guide belt 84, to be oriented parallel to the endless belts 48 and guide rails 50.

[0049] The guide 28, as well as the gage 30 and the motor 32, is carried by the conveyor 26. A mounting fixture 102 is provided for this purpose. The mounting fixture 102 allows for adjustability in mounting the guide 28 to achieve the previously discussed parallel orientation of the guide belt 84 relative to the endless belts 48 and guide rails 50. In this regard, the mounting fixture 102 included both a primary mounting portion 104, which allows for initial mounting of the guide 28 to the conveyor 26, a vertical adjustment assembly 105 and a final adjustment assembly 106, the latter allows for fine tuning of the parallel orientation. The final adjustment assembly 106 may include a pair of adjustment members to precisely control and set the orientation of the guide 28. In order to allow larger diameter parts to be run through the same thrufeed gage assembly 14, the vertical adjustment assembly 105 can be readily adjusted in conjunction with the final adjustment assembly 106.

[0050] Preferably, the mounting of the guide 28 to the conveyor 26 allows for a predetermined amount of vertical float to accommodate the workpieces 38 as they initially engage the guide 28 and the conveyor 26. The spring rate exhibited by the guide 28 is preferably the spring rate inherent as a result of the material and construction of the guide belt 84, as well as the weight of the guide 28. This float, however, does not allow for variation in the orientation of the guide belt 84 relative to the guide rails 50 and the endless belt 48.

[0051] With the conveyor 26 and the guide 28 properly positioned, the path of travel of the workpieces 38 is centrally between the conveyor 26 and the guide 28. As the workpieces 38 move along the path of travel, they are initially transported by the endless belts 48. Upon reaching the lead intermediate pulley 58, the workpieces 38 begin to be engaged by the guide belt 84 and are transferred from the endless belts 48 onto the guide rails 50 and into what is herein referred to as the gaging zone. While on the guide rails 50, the workpieces 38 are conveyed solely by the guide belt 84. It is at this point in time, while the workpieces are positioned between the guide rails 50 and the guide belt 84, that the workpieces 38 are measured by the gage 30.

[0052] The gage 30 may be one of variety of gages well known in the industry for measuring cylindrical workpieces. One such gage is described in U.S. patent number 5,643,049, which is herein incorporated by reference. Generally, the gage 30 includes a transducer (not shown) and a means to support a pair of gage arms 98 terminating in gage contacts 100, the latter being constructed of carbide or similar material. The gage arms 98 carry the contacts 100 so that the contacts engage the diameter of each workpiece 38 on opposite sides, allowing the diameter of each workpiece 38 to be measured along the length of the workpiece 38 without requiring fixturing of the workpiece 38. With the present construction, the gage arms 98 extend down from the body of the gage 30 and around opposing sides of the guide 28. The gage arms 98 therefore exhibit a downward offset, as readily seen in figures 5-6B.

[0053] The control panel 36 is used to control the speed of the motor 32, and therefore the speed of the conveyor 26 and the guide 28. Additionally, the control panel 36 receives and processes the signals from the gage 30, and will subsequently activate the diverter 34 in the event that the gage 32 detects an unsatisfactory workpiece 38. The control panel 36 may include a single controller configured to operate the various subassemblies of the thrufeed gaging station 10 or may alternatively include separate controllers for the subassemblies. For example, the gage 30 may include its own controller for analyzing signals of the gage 30.

[0054] In an alternative to the V-belt construction of the guide belt 84, a guide belt

184 having a central channel or notch 186 may be provided. As seen in the cross-sectional view of Figure 7, the notch 186 of the guide belt 184 is defined by opposing legs 188 that extend from a base portion 190. When engaged with the workpiece 38, inside corners or portions 192 of the legs 188 each contact the workpiece 38. This engagement of the workpiece 38 ensures that the workpiece 38 remains centered and aligned while engaged with the guide belt 184 and while traversing the gaging zone.

[0055] Referring now to Figure 8, seen therein is an alternate construction for the guide 28. The guide 228 of this alternative construction replaces the single endless guide belt 84, drive pulley 86, return pulley 88 and idler pulley 90 of the guide 28. These components are respectively replaced with a pair of endless guide belts 284, a dual drive pulley 286, a dual return pulley 288 and, optionally, omission of any idler pulley. [0056] The guide belts 284 are provided about the pulleys 286, 288 in a side-by-side or parallel configuration and are preferably provided as round tubing. The material forming the round tubing of the guide belts 284 provides sufficient compliancy to allow the guide belts 284 to isolate the individual workpieces 38 from one another as they are engaged and are transported by the guide belts 284. In one preferred construction, the guide belts 284 are made of urethane, which may or may not be reinforced with a nylon or Kevlar core. Other materials may alternatively be utilized so long as they provide the requisite compliancy for the given application.

[0057] The drive and return pulleys 286, 288 are similar in construction to the dual pulleys 54 of the conveyor 26 and include two adjacent grooves for receiving the pair of guide belts 284 in a side-by-side arrangement. Being provided in a side-by-side arrangement, the workpieces 38 are received between the individual guide belts 284, which ensures that the workpieces 38 remain centered and aligned while traversing the gaging zone. Because the round tubing of the guide belts 284 is available in wide variety of sizes and materials, the idler pulley 90 of the previously discussed alternative may be omitted, if desired.

[0058] Other than the changes in components mentioned herein, this alternative construction for the guide 228 includes the same components and operates in the same manner as the previously discussed guide 28. Accordingly, further discussion of the related components and operation of the guide 228 is omitted in the interest of brevity, reference being herein made to the prior discussion thereon. As a person skilled in the art will readily appreciate, the above description is meant as an illustration of implementation of the principles this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from spirit of this invention, as defined in the following claims.