CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to prior-filed co-pending U.S. Provisional Patent Application No. 63/399,904, filed on August 22, 2022, the entire contents of which are incorporated by reference herein.

BACKGROUND

[0002] Precision machining of mechanical components, such as bearings, is routinely fulfilled with CNC machine tools. Rough turning and finish turning are the two primary processes involved to remove unwanted materials and obtain the desired dimensions and surface finish of the workpiece in the machining process. However, most of the precision components require extremely smooth surfaces, but also finish-turned surfaces are often insufficient to achieve the desired surface finish. Consequently, they require additional superfinishing on a specialized machine, known as honing machine. Honing is a finishing process that uses bonded cutting grain to improve the size, dimensional accuracy, and surface finish of a workpiece while maintaining constant surface contact with the tool. In most cases, honing is performed after precision machining, such as grinding or turning. It is achieved by applying abrasive stones of the appropriate grit and grade to the work surface. Therefore, the additional honing process will inevitably increase the cycle time, thereby reducing output and increasing production costs. SUMMARY

[0003] The invention relates to a singular, combined turning and honing tool that enables the CNC lathe to perform a honing process during or after turning, without the need for additional tools or tool switching.

[0004] Tn one aspect, the invention provides an integral tool holder for turning and honing for CNC machine tools. The body of the integrated turning and honing tool holder defines a feed direction, a cutting direction perpendicular to the feed direction, and a depth direction perpendicular to both the feed and cutting directions. The cutting portion is fixed in relation to the body's top end. The cutting portion specifies the direction of the tip. The honing portion is located beneath the cutting portion, and the direction of honing is parallel to or angled with respect to the direction of the tip. The cutting portion and honing portion are stacked in the cutting direction. The honing portion is covered up within the body during the cutting process but is activated and extended outside the body during the honing process. A relative position is established between the cutting and honing portions so that the honing process can be performed after the cutting process. The invention adds honing capabilities to tool holders for turning that are driven by pressurized coolant, thereby enabling a CNC lathe to perform turning and honing without requiring an additional tool or device. By providing a honing feature with the tool holder, the surface finish of the finish turned component can be extensively improved on the CNC lathe without the need to be further processed on a honing machine.

[0005] In a second aspect, the invention provides a method for precision machining, specifically a method for integral turning and honing machining. The workpiece is simultaneously honed with the honing portion located below the upper cutting portion or after the cutting process performed by the cutting portion. The honing process is powered by a pressurized coolant, meaning no additional power source, such as a living tool is required Tn addition, the honing force is adjustable by adjusting the coolant pressure from the supply. The compatible honing stones are available in a range of harnesses and grit sizes based on the superfinishing requirement. The workpiece may be honed while feeding in or feeding out.

[0006] The invention provides of a series of advantages: The primary benefit is the ability to add honing capability to a conventional CNC lathe and tool holder without the need for additional tools, thereby enhancing the surface finish of the processed surface. Second, the honing system can be concealed within the tool holder when not in use so that it does not interfere with the turning process. Thirdly, the tool holder does not necessitate a separate powering system. The pressurized coolant drives the honing operation. Fourthly, the attached honing abrasive can be replaced, and the honing pressure can be adjusted by varying the coolant pressure. Other aspects will be described in greater detail in the drawings below.

BRIEF DESCRIPTION OF THE DRAWING

[0007] FIG. 1 is a perspective view of an integral tool holder for turning and honing, according to one embodiment of the present disclosure. The honing portion is shown extended. [0008] FIG. 1A is a section view of the integral tool holder of FIG. 1.

[0009] FIG. 2 is an exploded view of the integral tool holder for turning and honing of FIG. 1.

[00010] FIG. 3 is a section view of the integral tool holder of FIGS. 1 and 2, showing the honing portion retracted.

[00011] FIG. 4 is a perspective view of an exemplary workpiece turning operation on a lathe. [00012] FIG. 5 is a plan view of the integral tool holder in position to hone a cylindrical side surface of a lathe-mounted workpiece.

[00013] FIG. 6 is a plan view of the integral tool holder in position to hone an end surface of the lathe-mounted workpiece.

[00014] FIG. 7 is a perspective view of an integral tool holder for turning and honing, according to another embodiment of the present disclosure, wherein the cutting and honing portions have respective tip angles offset from each other.

DETAILED DESCRIPTION

[00015] Before any embodiments of the invention are described in detail, it should be understood that the invention is not limited in its application to the construction details and component arrangement described in the following description or depicted in the following drawings. The invention is capable of other embodiments and of being practiced or carried out in a number of different ways.

[00016] A CNC lathe is commonly used for turning precision components which requires a fine surface finish. As known in the art, turning is a cutting operation whereby the workpiece 100 is spun about a central axis A on a lathe, as shown in FIG. 4, while a cutting tool is brought into contact with a surface of the workpiece 100. Turning can be classified as either rough turning or finishing turning. Typically, the finish turning is the final turning operation that can be performed on a CNC lathe. However, in order to meet the required surface finish standard for the precision component, most of the time, the workpiece must be transferred to a super finishing machine for a honing process after the finish turning process. This additional honing procedure increases cycle time and production costs. The invention integrates honing capability into a turning tool holder on a CNC lathe, allowing a typical CNC lathe to perform the superfinishing process The CNC lathe can perform the superfinishing process (directly) after the finish turning process. It eliminates the need for a superfinishing machine in a component finishing process, which extensively reduces manufacturing costs and increases productivity.

[00017] The illustrated embodiment includes a dual-function tool 20 for cutting and honing on a lathe. The tool 20 comprises a tool holder or body 8 (e.g., formed as a shank body) that defines a cutting direction C in which the tool 20 faces for engaging and cutting into a workpiece 100 during a metalworking cutting (e.g., turning) operation. The cutting direction C is perpendicular to the surface of the spinning workpiece 100 and directly opposite to the workpiece rotation direction at the point of contact. The tool 20 further defines a feed direction F perpendicular to the cutting direction C (and parallel to the axis A of the spinning workpiece 100 on the lathe). While the tool 20 may typically be fixed in the cutting direction C, movement of the tool 20 in the feed direction F produces an axial length of the cutting operation along the surface of the spinning workpiece 100. A depth direction D of the tool 20 is perpendicular to both the feed direction F and the cutting direction C. Movement of the tool 20 in the depth direction D adjusts the amount of overlap between the cutting tip of the tool 20 and the workpiece 100 to change depth of cutting and chip load. In other words, depth direction movement of the tool 20 moves the cutting tip toward or away from the central axis A of the spinning workpiece 100 on the lathe. The exception is end turning (FIG. 6), where the tool 20 can be oriented for working on an axial end surface of the workpiece 100. In that case, the depth direction D is parallel to the workpiece/lathe rotational axis A, and the feed of the tool 20 is toward or away from the axis A.

[00018] The tool 20, and in particular the body 8, consists of two functional sections adjacent the distal or tip end. The cutting portion 24 is located at the top side of the body 8 (i.e., forward in the cutting direction C). The honing portion 28 is situated below the cutting portion

24 (i.e., behind the cutting portion 24 in the cutting direction C). Thus, the cutting and honing portions 24, 28 are spaced apart from each other and stacked in the cutting direction C. A relative position between the cutting and honing portions 24, 28 is determined in order to complete the honing process following the cutting process. The honing portion 28 can be selectively retracted or concealed within the body 8 (FIG. 3) when cutting with the cutting portion 24. The operation of honing with the honing portion 28 can be performed during cutting with the cutting portion 24 (simultaneous cutting and honing), or after cutting with the cutting portion 24 (sequential cutting and honing). When honing, it is possible to extend a honing insert 3 (i.e., stone) of the honing portion 28 from the body 8, and the amount of extension may be adjustable in some constructions.

[00019] FIG. 1A is a cross-sectional illustration of the exemplary tool 20 with the honing portion 28 activated or deployed, and FIG. 2 is an explosion illustration. FIG. 3 is a cross-section like FIG. 1 A, but with the honing portion 28 retracted. The tool 20 includes the shank body 8, the cutting insert 4 of the cutting portion 24, an insert shim 9, a piston 5, a spring 11, the honing stone 3 of the honing portion 28, and various fasteners (e.g., set screws 1, 2, 6, 12). The conventional turning function is carried out by the cutting portion 24, which is fulfdled by the turning insert 4, the shim 9, and the screw 10 for securing with the body 8. The integrated honing feature is fulfdled by the piston 5 that holds the honing stone 3. The set screws 1, 2, and 6 are for blocking and guiding the coolant flow from a coolant source 40 (e g., receiving pressurized coolant through the opening 21 with the set screw 1 removed while the other set screws 2, 6 are in place to block coolant escape). The set screw 12 is for locking the honing stone 3.

Accordingly, this invention has multiple modes of operation. One operating mode is simply a turning operation using only the cutting portion 24. However, the tool 20 also enables the coolant-driven honing mode. As mentioned, the honing mode can be simultaneous with cutting, or following cutting - directly, without changing tools and without moving the workpiece 100 to a different machine or workstation.

[00020] The cutting insert 4 and the shim 9 are assembled into a receptacle 13 of the body 8 to form the cutting portion and configure the tool 20 for cutting (e.g., turning operations) on the lathe-mounted workpiece 100. The honing stone 3 is inserted into the hole opening 14 at the distal end of the piston 5 and locked with the set screw 12 on the side of the piston 5. The assembled piston 5 with the honing stone 3 is inserted into the hole opening 15 with the spring 11 in between the step 16 on the piston 5 and the body 8. Thus, the piston 5 is biased to a retracted position (FIG. 3) by the spring 11 bearing against the body 8, at a shoulder thereof. The inserted honing portion 28 assembled as described above is then restrained to a limited amount of extension by the insert screw 10 from the cutting portion 24, and it is locked within the body 8 from the back side with the set screw 6. Additional set screws 1, 2 may be inserted to block the flowing way of the coolant in the depth direction D and cutting direction C.

[00021] When the insert 4 is brought to engagement with the workpiece 100, the cut surface can spin directly toward and into engagement with the honing portion, particularly the tip of the honing stone 3. With this understanding, as shown in FIG. 1, in the assembled position and honing portion is activated, the honing stone 3 with a portion of the piston 5 extends outward from the body 8 in the honing tip direction Th. The honing tip direction Th can be parallel to and point in the same direction as a longitudinal axis or cutting tip direction T _c of the cutting insert 4. In other constructions (FIG. 7), the honing stone 3 can be oriented off-axis with the cutting insert 4, such that there is a small angle between two respective tip directions (e.g., depending on the insert seating types/tool holder types). Tn one exemplary embodiment, there is a minor tool holder side clearance angle of approximately 6 degrees.

[00022] The cutting tip direction T _c can be oriented at a small angle a (e.g., less than 30 degrees, or less than 15 degrees) away from the depth direction D and toward the feed direction F. This is more clearly shown in the plan view of FIG. 5, including the workpiece 100. The honing tip direction Th can lie in the plane defined by the feed and depth directions F, D such that it is also perpendicular to the cutting direction C. Although not coincident with each other due to the physical spacing therebetween, the tip directions Th and T _c of the honing stone 3 and the cutting insert 4 can lie in a single reference plane that is parallel to the cutting direction C (FIG. 5 views directly along the cutting direction C with the two tip directions Th and T _c overlapping each other). The honing operation can be processed simultaneously with the cutting process in this configuration. In other words, a surface portion of the workpiece 100 is cut to size and honed in the same pass of the workpiece 100 along the tool 20, while the workpiece 100 remains in motion on the lathe. The singular tool 20 remains in the working position and need not be removed or reconfigured between cutting and honing. At the same time, two adjacent portions of the workpiece surface are engaged by the insert 4 and the honing stone 3, respectively.

[00023] The integral cutting and honing tool 20 can operate as follows:

• Turning: The pressurized coolant from the supply 40 is not turned on, so the honing portion 28 is biased by the spring 11 and remains hidden inside the body 8. In some constructions, the honing stone 3 is extended from the body 8, but to an extent less than the insert 4. Only the cutting portion 24 is active, the workpiece 100 only being contacted by the insert 4. • Honing: The pressurized coolant from the supply 40 is activated and flows into the passage in the body 8 through the opening 21 and pushes onto the rear or internal end surface of the piston 5. The spring is compressed, and the piston is pushed outside the body 8 to apply to hone force on the surface of the workpiece 100.

• After honing, the pressurized coolant from the supply 40 is turned off, the spring 1 1 is then restored from compression, and the honing portion 28 is retracted.

[00024] The honing force can be estimated as the equation: where the a is the angle between the honing tip direction Th and the depth direction D when honing a (cylindrical side) surface of the workpiece 100 normal to the depth direction D (and parallel to the lathe axis A) as shown in FIGS. 4 and 5. However, the tool 20 can be oriented on the lathe to hone an end surface of the workpiece 100 that is perpendicular to the lathe axis A as shown in FIG. 6. In such a construction, the angle a in the expression above is replaced by a _x which is defined as the angle between the honing tip direction Th and the feed direction F. Pcooiant is the coolant force, which can be determined by:

^coolant ^coolant Api _S f _On where P _CO oiant is the coolant pressure, A _piston is the back-end surface 17 area of the piston 5. [00025] FIG. 7 illustrates a tool 20’ that can conform to the above described elements and features, except as noted specifically below. The tool 20 includes the honing stone 3 and the cutting insert 4, the two of which extend at different or offset tip angles Th, T _c . In other words, the honing stone 3 can be oriented off-axis with the cutting insert 4, such that there is a small angle between two respective tip directions. [00026] Thus, the tool 20 as shown and described integrates a honing function into the tool holder that supports the cutting insert 4. It is different from the traditionally used turning tool holder and a specialized honing tool holder. In addition, the honing process relies upon maintained coolant pressure inside the tool holder body 8 to maintain the honing force. The tool 20 can be used to cut a wide variety of materials, including hardened or unhardened, and for a host of products, including but not limited to bearing rollers, without deviating from the spirit of the current invention. Those of skill in the art will appreciate other possible variants and/or embodiments. They shall be considered under the scope of the present invention.