Workpiece processing device, grindstone, and workpiece processing method

Abstract

In the present invention, a recessed grinding part 5b of an outer peripheral portion of a grindstone 5 has arc-shaped parts 5e at both ends in the thickness direction and a linear part 5h between the arc-shaped parts. A workpiece 2 and the grindstone 5 are arranged in parallel, and the grindstone 5 is moved relative to the workpiece 2 under a moving condition calculated on the basis of the radius of curvature of the arc-shaped parts 5e so that a contact portion between the recessed grinding part 5b and the workpiece 2 moves along a desired cross-sectional shape of the workpiece 2 while the workpiece and the grindstone are rotated. The radius of curvature of the arc-shaped parts 5e is 10 times or more of the thickness of the workpiece 2 so that the arc-shaped parts 5e of the grindstone 5 abut on the workpiece 2 without creating a gap between the arc-shaped parts and a chamfered portion 2a of the desired cross-sectional shape. A lower surface of the workpiece 2 is picked up by a pick-up member 10, and the lower arc-shaped part 5e has a length which is equal to or greater than a length of the chamfered portion 2a on the lower side of the workpiece 2 having the desired cross-sectional shape, and which is less than a length to abut on the pick-up member 10 in a state of contact with an end portion of the lower surface of the workpiece 2 at a position where a tangent line extends at the same angle as a tapered shape 10a of the pick-up member 10.

Description

Workpiece processing device, grinding wheel, and workpiece processing method

[0001] The present invention relates to a workpiece machining device, a grinding wheel, and a workpiece machining method.

[0002] Conventionally, chamfering the outer periphery of a disc-shaped workpiece (workpiece) such as a semiconductor wafer involves pressing a grinding wheel against the workpiece's outer periphery. To improve the shape and dimensional accuracy of the chamfered portion of the workpiece, one method involves forming a groove (formed groove) on the outer periphery of the grinding wheel with a shape and dimensions corresponding to the finished shape of the workpiece, inserting the outer periphery of the workpiece into the groove, and rotating the workpiece to grind the outer periphery of the workpiece using the inner periphery of the groove. However, this method requires replacing the grinding wheel every time the shape or dimensions of the workpiece to be manufactured change, making it unsuitable for small-lot production of a wide variety of products. Furthermore, repeated chamfering operations can wear or damage the inner periphery of the groove on the outer periphery of the grinding wheel, changing the shape and dimensions of the groove and reducing the accuracy of the workpiece chamfering. Therefore, after chamfering a workpiece for a long period of time, the grinding wheel must be replaced or reshaped.

[0003] In order to replace or reshape a grinding wheel as needed, the methods described in Patent Documents 1 and 2 involve preparing a master grinding wheel with a formed groove corresponding to the finished shape of the workpiece. The outer periphery of the grinding wheel material is then abutted against the inner periphery of the groove of the master grinding wheel and ground to produce a truing grinding wheel (truer), which is a mold material. Furthermore, by abutting the outer periphery of the truing wheel against the grinding wheel material to form a formed groove similar to that of the master grinding wheel, the shape of the grinding wheel for use in chamfering the actual workpiece can be adjusted (shaped). The truing wheel is made of a material (e.g., a GC grinding wheel) that is harder than the grinding wheel used for chamfering (e.g., a resin-bonded grinding wheel), and the master grinding wheel is made of a material (e.g., a metal-bonded grinding wheel) that is harder than the truing wheel. This process of shaping a grinding wheel using a truing wheel is called truing.

[0004] Patent Documents 1 and 2 suggest a method of chamfering a workpiece using a formed groove in a circular grinding wheel arranged parallel to the workpiece, as well as a method of chamfering a workpiece using a groove in a circular grinding wheel arranged at an angle to the tangent direction of the outer periphery of the workpiece (helical grinding method). A helical chamfering method is also described in Patent Document 3. In the method described in Patent Document 3, the grinding wheel arranged at an angle to the tangent direction of the outer periphery of the workpiece has a concave groove formed on its outer periphery and an inwardly inclined surface. Grinding is performed by abutting this inclined surface against the outer periphery of the workpiece. Patent Document 4 discloses a grinding method in which grinding is performed using a circular grinding wheel arranged parallel to the workpiece, and then more precise grinding is performed using a helical grinding method using a circular grinding wheel arranged at an angle to the tangent direction of the outer periphery of the workpiece, as well as a truing grinding wheel and a truing method for truing a grinding wheel for precision helical grinding.

[0005] As described in Patent Documents 1 to 4, when a workpiece is chamfered using a grinding wheel positioned at an angle to the tangent direction of the outer periphery of the workpiece, grinding is performed with a long contact area between the inner periphery of the grinding wheel and the outer periphery of the workpiece, and by grinding the workpiece while rotating it at a low speed, the surface roughness of the chamfered portion of the workpiece can be reduced, making it easier to carry out the finish polishing process that is performed later.

[0006] Patent Document 5 discloses a method for chamfering a workpiece by using a grinding stone having a groove on its outer periphery that is larger than the thickness of the workpiece, and abutting the inner peripheral surface of the groove on the grinding stone against the outer periphery of the workpiece. Patent Document 5 also discloses a method for chamfering a workpiece by using a grinding stone that is thicker than the workpiece, has no groove on its outer periphery, and has a convex cross-sectional shape on its outer periphery, and abutting an inclined surface that constitutes part of the convex portion on the outer periphery of the grinding stone against the outer periphery of the workpiece.

[0007] In the method described in Patent Document 6, a disc-shaped grinding wheel is placed perpendicular to a disc-shaped workpiece. The workpiece is rotatable around a rotation axis located at the center of its planar shape. The grinding wheel is rotatable around a rotation axis perpendicular to the workpiece's rotation axis and is also movable in a direction perpendicular to the rotation axis (a direction parallel to the disc-shaped workpiece) and a direction parallel to the rotation axis (a direction perpendicular to the disc-shaped workpiece). While the workpiece is rotating, the grinding wheel is rotated and brought closer to the workpiece. The outer periphery of the rotating grinding wheel is brought into contact with the outer periphery of the workpiece, which is rotating in a direction perpendicular to the rotation direction of the grinding wheel, and the grinding wheel is moved to chamfer the workpiece. This processing process is called contouring.

[0008] The method described in Patent Document 7 uses a cup-shaped grinding wheel that is positioned perpendicular to a disk-shaped workpiece, and, similar to Patent Document 6, the cup-shaped grinding wheel is rotated and brought close to the workpiece while the workpiece is rotating. The cup-shaped grinding wheel is moved while the cup-shaped tip surface of the rotating cup-shaped grinding wheel is brought into contact with the outer periphery of the workpiece that is rotating in a direction perpendicular to the rotation direction of the cup-shaped grinding wheel, thereby chamfering the workpiece.

[0009] Patent Document 8 discloses a method of performing chamfering in the same manner as Patent Document 6 using two disc-shaped grinding wheels, and a method of performing chamfering in the same manner as Patent Document 7 using two cup-shaped grinding wheels.

[0010] In the method described in Patent Document 9, the outer periphery of the workpiece is machined using a first grinding wheel that is a large, double-layered cup-shaped grinding wheel having an inner grinding element (cup-shaped) and an outer grinding element (cup-shaped) for more precise grinding than that achieved by the inner grinding element, and a second cup grinding wheel.

[0011] In the method described in Patent Document 10, in the peripheral edge diameter reduction process of the wafer, two grooveless grinding wheels are held at a fixed height and brought into contact with the wafer to perform the process, and in the contouring process, the two grooveless grinding wheels are moved separately to each side of the peripheral edge of the wafer, and the same radial location of the peripheral edge of the wafer is sandwiched from above and below, and each side is processed simultaneously.

[0012] In the method described in Patent Document 11, a disc-shaped grinding wheel having a convex grinding portion on its outer periphery is used, the disc-shaped workpiece and the grinding wheel are arranged parallel to each other, and while the grinding wheel and workpiece are rotated, the grinding wheel is moved relative to the workpiece in accordance with movement conditions calculated based on the radius of curvature of the arc-shaped portion of the grinding wheel so that the contact portion between the convex grinding portion and the workpiece moves along the desired cross-sectional shape of the workpiece.

[0013] Japanese Patent Application Laid-Open No. 2005-153085 Japanese Patent Application Laid-Open No. 2007-165712 Japanese Patent Application Laid-Open No. 5-152259 Japanese Patent Application Laid-Open No. 2007-044817 Japanese Patent Application Laid-Open No. 11-207585 Japanese Patent Application Laid-Open No. 2000-317789 Japanese Patent Application Laid-Open No. 2008-034776 Japanese Patent Application Laid-Open No. 2014-37014 Japanese Patent Application Laid-Open No. 2017-154240 Japanese Patent Application Laid-Open No. 2008-177348 Japanese Patent No. 7093875

[0014] As described in Patent Documents 1 to 4, it is not easy to form grooves for chamfering a workpiece with high precision on the outer periphery of a grinding wheel that is positioned at an angle relative to the tangent direction of the workpiece's outer periphery. To form a desired chamfer on a workpiece, the inner periphery of the groove must contact the outer periphery of the workpiece at an appropriate angle and with an appropriate contact length. It is difficult to form a groove with an inner periphery that accurately contacts the outer periphery of the workpiece at an appropriate angle and with an appropriate contact length when using a grinding wheel that is positioned at an angle relative to the tangent direction of the workpiece's outer periphery. In particular, when truing is performed by rotating a truing wheel using a drive unit that rotates the workpiece or a drive unit that rotates a grinding wheel used to grind the workpiece, it is difficult to form grooves with high precision that allow for good chamfering when the grooves are tilted relative to the tangent direction of the workpiece's outer periphery. Therefore, a method for easier truing is needed. Furthermore, if the shape or dimensions of the chamfered portion of the workpiece to be manufactured change, the shape of the groove on the master grinding wheel used to create the truing wheel must also be changed, which is a cumbersome process.

[0015] When machining a workpiece using a grinding wheel that is tilted obliquely relative to the tangent direction of the workpiece's outer periphery, the shape and dimensions of the inner peripheral surface of the groove cannot be easily changed, making it difficult to make fine corrections to approximate the desired machined shape. Therefore, when manufacturing a wafer having an orientation flat as the workpiece, it is not possible to accurately form the orientation flat using the grooves of a grinding wheel that is tilted obliquely relative to the tangent direction of the workpiece's outer periphery, which are primarily intended to form the arc-shaped portion of the workpiece's outer periphery. Therefore, the groove for forming the orientation flat must be formed separately from the groove for forming the arc-shaped portion, which makes the manufacture of the grinding wheel more complicated and increases the machining time required to use two grooves separately.

[0016] In the method described in Patent Document 5, the outer periphery of a workpiece is ground by contacting it with an inclined surface that is part of the inner periphery of the grinding wheel groove or a convex portion of the outer periphery of the grinding wheel. Since the outer periphery of the workpiece is ground by moving the workpiece relatively along the inclined surface of the grinding wheel, the shape of the ground outer periphery of the workpiece corresponds to the inclined surface of the grinding wheel. Because the angle of the inclined surface of the outer periphery of the grinding wheel cannot be arbitrarily changed, it is difficult to form the chamfered portion of the workpiece into an arbitrary shape. Furthermore, grinding is performed by moving the workpiece back and forth (traverse) relative to the grinding wheel at the chamfered portions on both sides of the workpiece, the straight portion at the tip, and the curved portion between the straight portion and the chamfered portion, resulting in complex processing and a long processing time.

[0017] In the method described in Patent Document 6, a disc-shaped grinding wheel is positioned perpendicular to the disc-shaped workpiece. Therefore, if a large grinding wheel is used, the grinding wheel may interfere with mechanisms for supporting and driving the workpiece (e.g., a vacuum table or a rotation mechanism). Therefore, to avoid interfering with stable support and smooth driving of the workpiece, a small grinding wheel is used instead of a large one. As a result, processing efficiency is reduced and processing time is extended. Furthermore, when chamfering the same workpiece, a small grinding wheel spends more time in contact with the outer periphery of the workpiece than a large grinding wheel, resulting in a shorter grinding wheel life. Furthermore, the workpiece moves along a trajectory such that the contact points with the grinding wheel follow the desired cross-sectional shape. However, since each point on the workpiece is sufficiently ground before the workpiece moves, the workpiece must rotate at a high speed to achieve high efficiency. In this way, grinding is performed while the workpiece is rotated at high speed, and scratches from the grinding wheel rotating in a direction perpendicular to the workpiece's rotation are formed on the outer surface of the workpiece in a shape that extends along the thickness of the workpiece, resulting in a high surface roughness in the ground portion. Even if a more precise polishing process is performed after this grinding process, polishing is difficult due to the presence of scratches that run perpendicular to the workpiece's rotation. In particular, the inclined surface of the workpiece is difficult to polish in the subsequent precision polishing process, and there is a possibility that scratches will remain because the workpiece is not polished sufficiently.

[0018] In the method described in Patent Document 7, the production of the cup-shaped grinding wheel is complicated, and truing is particularly difficult. In addition, it is not easy to position and drive the cup-shaped grinding wheel so that the tip surface of the cup shape appropriately contacts the outer periphery of the workpiece, and the mechanism for supporting and driving the cup-shaped grinding wheel is complex.

[0019] In addition to the problems with the methods described in Patent Document 8, which are described in Patent Documents 6 and 7, the method described in Patent Document 8 has the following problems: the device is complicated because two grinding wheels are driven simultaneously, and differences in size and shape are likely to occur between the two grinding wheels, making it difficult to perform stable, high-precision chamfering.

[0020] In the method described in Patent Document 9, the shape of the first grinding stone is very complex, and manufacturing the first grinding stone is cumbersome. In addition, since the workpiece is rotated around two rotation axes, the mechanisms for supporting and driving the workpiece are also complex. As such, the processing device for implementing the method described in Patent Document 9 is very complex.

[0021] In the method described in Patent Document 10, similar to the method described in Patent Document 6, grinding is performed using a circular grinding wheel arranged perpendicular to the circular workpiece. Furthermore, this method requires a mechanism using a piezoelectric element to adjust the thickness position of the workpiece rotating at high speed, which makes the processing equipment complex and expensive. Furthermore, since the workpiece is rotated while constantly adjusting its thickness position, the accuracy of forming the desired cross-sectional shape tends to be poor. In particular, it is difficult to maintain a constant radius (R dimension) of the arc-shaped portion of the desired cross-sectional shape of the workpiece around the entire circumference of the circular workpiece.

[0022] In the method described in Patent Document 11, the convex grinding portion on the outer periphery of the grinding wheel approaches the workpiece while grinding, resulting in large loads and vibrations during grinding. Furthermore, because the radial volume of the convex grinding portion is large, the weight of the grinding wheel and the moment of inertia during rotation are large. As a result, vibrations during rotation of the grinding wheel tend to increase, leading to high manufacturing costs for the grinding wheel. Furthermore, even if grinding water (coolant) is supplied to the contact area between the grinding wheel and the workpiece during grinding, the grinding water that comes into contact with the convex grinding portion tends to splash, making it difficult to perform efficient and smooth grinding.

[0023] The present invention aims to provide a workpiece processing device, a grinding wheel, and a workpiece processing method that can easily, efficiently, and accurately chamfer a workpiece, that has a simple mechanism for supporting and driving the workpiece and grinding wheel, and that can easily shape the grinding wheel.

[0024] The workpiece processing device of the present invention for forming a disc-shaped workpiece into a desired cross-sectional shape includes a workpiece support mechanism that supports the workpiece, a disc-shaped grinding wheel that is arranged parallel to the workpiece, and a grinding wheel support mechanism that supports the grinding wheel, wherein the workpiece support mechanism rotates the workpiece, the grinding wheel support mechanism rotates the grinding wheel, and the rotation axis that is the center of rotation of the workpiece by the workpiece support mechanism and the rotation axis that is the center of rotation of the grinding wheel by the grinding wheel support mechanism are parallel to each other, and the workpiece support mechanism adsorbs only one side of the workpiece. The grinding wheel has a concave grinding portion on its outer periphery, and the cross-sectional shape of the concave grinding portion in a cross section along the rotation axis of the grinding wheel is a concave shape recessed from the outer periphery side toward the inner periphery side, and has arc-shaped portions at both ends in the thickness direction, and between the arc-shaped portions at both ends, there is a gap having a thickness equal to or greater than the thickness of the workpiece and a diameter of the workpiece. the grinding wheel has a shape having a straight portion for grinding for at least one of reducing the size of the workpiece and smoothing the middle portion of the outer periphery of the workpiece in the thickness direction, the grinding wheel and the workpiece can be moved relatively toward or away from each other by the grinding wheel support mechanism or the workpiece support mechanism, the grinding wheel support mechanism or the workpiece support mechanism moves the grinding wheel relatively to the workpiece in accordance with movement conditions calculated based on the radius of curvature of the arc-shaped portion of the grinding wheel so that the contact portion between the concave grinding portion and the workpiece moves along the desired cross-sectional shape of the workpiece, the radius of curvature of the arc-shaped portion of the grinding wheel is at least 10 times the thickness of the workpiece so that the arc-shaped portion of the grinding wheel abuts against the workpiece without generating a substantial gap between it and the chamfered portion of the desired cross-sectional shape of the workpiece, the arc-shaped portion located on the one surface side of the workpiece that is attracted by the attraction member has a length equal to or longer than the chamfered portion of the one surface side of the workpiece of the desired cross-sectional shape in a cross section along the rotation axis of the grinding wheel, andThe tangent of the arc-shaped portion has a length less than the length at which it abuts against the tapered shape of the suction member in a state where it is in contact with the end of the one surface of the workpiece at a position where it extends at an angle that coincides with the angle of the tapered shape of the suction member.

[0025] Another workpiece processing device for forming a disc-shaped workpiece into a desired cross-sectional shape of the present invention includes a workpiece support mechanism for supporting the workpiece, a disc-shaped grinding wheel arranged parallel to the workpiece, and a grinding wheel support mechanism for supporting the grinding wheel, wherein the workpiece support mechanism rotates the workpiece, the grinding wheel support mechanism rotates the grinding wheel, and the rotation axis around which the workpiece is rotated by the workpiece support mechanism and the rotation axis around which the grinding wheel is rotated by the grinding wheel support mechanism are parallel to each other, and the workpiece support mechanism has an adsorption member that adsorbs only one side of the workpiece. The planar shape of the attraction member is a circle having a radius smaller than the radius of the workpiece, the outer peripheral portion of the circular attraction member has a tapered shape in which the thickness decreases toward the outside, the grinding wheel has a concave grinding portion on the outer periphery, the cross-sectional shape of the concave grinding portion in a cross section along the rotation axis of the grinding wheel is a concave shape recessed from the outer periphery side toward the inner periphery side, and has at least an arc-shaped portion at each end in the thickness direction, and an inclined portion located outside the arc-shaped portion in the thickness direction and continuously connected to the arc-shaped portion, and a shape having a straight portion having a thickness equal to or greater than the thickness of the workpiece and performing grinding for at least one of reducing the diameter of the workpiece and smoothing the intermediate portion in the thickness direction of the outer periphery of the workpiece, the inclined portion extending along a tangent direction of the arc-shaped portion at the boundary position between the arc-shaped portion and the inclined portion, which matches the angle of the chamfered portion on one surface of the workpiece having the desired cross-sectional shape, and the grinding wheel and the workpiece can be moved relatively toward or away from each other by the grinding wheel support mechanism or the workpiece support mechanism. The grinding wheel support mechanism or the workpiece support mechanism moves the grinding wheel relative to the workpiece in accordance with movement conditions calculated based on the radius of curvature of the arc-shaped portion of the grinding wheel so that the contact portion between the concave grinding portion and the workpiece moves along the desired cross-sectional shape of the workpiece, and the radius of curvature of the arc-shaped portion of the grinding wheel is at least 10 times the thickness of the workpiece, and the inclined portion located on the one surface side of the workpiece that is attracted by the attracting member is, in a cross section along the rotation axis of the grinding wheel,The length is equal to or greater than the length of the chamfered portion on the one surface side, and when the angle formed by the direction in which the inclined portion extends with respect to the one surface side of the workpiece is smaller than the angle formed by the tapered shape of the suction member with respect to the one surface side of the workpiece, the length is less than the length at which the inclined portion abuts against the tapered shape of the suction member in a state in which the tangent to the arc-shaped portion extends at an angle that matches the angle of the tapered shape of the suction member.

[0026] The present invention provides a rotatable, disc-shaped grinding wheel having a concave grinding portion on its outer periphery, wherein the cross-sectional shape of the concave grinding portion in a cross section along the rotation axis of the grinding wheel is a concave shape recessed from the outer periphery toward the inner periphery, and has arc-shaped portions at least at both ends in the thickness direction, and has a straight portion between the arc-shaped portions at both ends that has a thickness greater than or equal to the thickness of the workpiece and performs grinding for at least one of reducing the diameter of the workpiece and smoothing the middle portion of the outer periphery in the thickness direction, by using the grinding wheel to grind a disc-shaped workpiece into a desired cross-sectional shape. a step of moving the grinding wheel relative to the workpiece in accordance with a movement condition calculated based on a radius of curvature of the arc-shaped portion of the grinding wheel so that a contact portion between the concave grinding portion and the workpiece moves along the desired cross-sectional shape of the workpiece, while rotating the grinding wheel and rotating the workpiece about a rotation axis parallel to the rotation axis of the grinding wheel; While rotating the workpiece attracted by an attraction member and the grinding wheel, the arc-shaped portion of the concave grinding portion of the grinding wheel is moved in a curved line from the outer peripheral end face of the workpiece toward one surface by an angle calculated in advance in accordance with the movement conditions, thereby grinding the outer periphery of the one surface side of the workpiece to form a chamfered portion of the workpiece having the desired cross-sectional shape; moving the grinding wheel along the outer peripheral end face of the workpiece from the one surface side to the other surface side; and while moving the workpiece, the circular arc-shaped portion of the concave grinding portion of the grindstone is moved in a curved line from the outer peripheral end face of the workpiece toward the other surface by an angle calculated in advance in accordance with the movement conditions, thereby grinding the outer periphery on the other surface side of the workpiece to form a chamfered portion of the workpiece having the desired cross-sectional shape, wherein the planar shape of the attraction member is a circle with a radius smaller than the radius of the workpiece, and the outer peripheral portion of the circular attraction member has a tapered shape whose thickness decreases toward the outside, and the circular arc-shaped portion of the grindstone isThe radius of curvature of the arc-shaped portion of the grinding wheel is at least 10 times the thickness of the workpiece so that the grinding wheel can abut against the workpiece without creating a gap between the workpiece and the chamfered portion of the desired cross-sectional shape of the workpiece, and the arc-shaped portion located on the surface of the workpiece that is attracted by the attracting member has a length equal to or greater than the length of the chamfered portion of the workpiece that has the desired cross-sectional shape on the surface of the workpiece that is attracted by the attracting member, in a cross section along the rotation axis of the grinding wheel, and a tangent to the arc-shaped portion is and a length that is less than the length that contacts the tapered shape of the attraction member in a state where the attraction member is in contact with the end of the one surface side of the workpiece at a position that extends at an angle that matches the angle of the tapered shape of the attraction member, and when rough grinding is performed on the outer periphery of the one surface side or the other surface side of the workpiece, the workpiece and the grinding wheel are rotated, and the arc-shaped portion of the concave grinding portion of the grinding wheel is moved from the outer periphery end face of the workpiece toward the one surface or the other surface, and the rotation axis of the grinding wheel and the and then, when performing precision grinding of the outer periphery of the one surface side or the other surface side of the workpiece, while rotating the workpiece and the grinding wheel, the arc-shaped portion of the concave grinding portion of the grinding wheel is moved in a curved line relative to the workpiece by an angle calculated in advance in accordance with the movement conditions from the outer periphery end face of the workpiece toward the one surface or the other surface so that the rotation axis of the grinding wheel and the rotation axis of the workpiece are positioned in the same plane, and then the movement of the grinding wheel relative to the workpiece is stopped.

[0027] A rotatable, disc-shaped grinding wheel having a concave grinding portion on its outer periphery, wherein the cross-sectional shape of the concave grinding portion in a cross section along the rotation axis of the grinding wheel is a concave shape recessed from the outer periphery side toward the inner periphery side, and has an arc-shaped portion at each end in the thickness direction, and a slope portion located outside the arc-shaped portion in the thickness direction and continuously connected to the arc-shaped portion, and a thickness greater than the thickness of the workpiece is provided between the arc-shaped portions at both ends for at least one of reducing the diameter of the workpiece and smoothing the middle portion in the thickness direction of the outer periphery of the workpiece. Another workpiece machining method for forming a disk-shaped workpiece into a desired cross-sectional shape using a grinding wheel having a shape with a straight portion for grinding includes the steps of: arranging the workpiece and the grinding wheel parallel to each other; and rotating the grinding wheel and rotating the workpiece about a rotation axis parallel to the rotation axis of the grinding wheel, while moving the grinding wheel relative to the workpiece in accordance with movement conditions calculated based on the radius of curvature of the arc-shaped portion of the grinding wheel so that a contact portion between the concave grinding portion and the workpiece moves along the desired cross-sectional shape of the workpiece. and a step of moving the grinding wheel relatively to the workpiece, wherein the step of moving the grinding wheel relatively to the workpiece includes: rotating the workpiece, only one surface of which is attracted by an attracting member, and the grinding wheel, while moving the arc-shaped portion of the concave grinding portion of the grinding wheel in a curved line from the outer peripheral end face of the workpiece toward one surface by an angle calculated in advance according to the movement conditions, thereby grinding the outer periphery on the one surface side of the workpiece to form a chamfered portion of the workpiece having the desired cross-sectional shape; and while rotating the workpiece and the grinding wheel, moving the arc-shaped portion of the concave grinding portion of the grinding wheel in a curved line from the outer peripheral end face of the workpiece toward the other surface by an angle calculated in advance in accordance with the movement conditions, thereby grinding the outer periphery of the other surface side of the workpiece to form a chamfered portion of the workpiece having the desired cross-sectional shape, wherein the planar shape of the attraction member is a circle with a radius smaller than the radius of the workpiece, and the circular outer peripheral portion of the attraction member isThe grindstone has a tapered shape that is thinner toward the outside, the radius of curvature of the arc-shaped portion of the grindstone is at least 10 times the thickness of the workpiece, the inclined portion extends along a tangential direction of the arc-shaped portion at a boundary position between the arc-shaped portion and the inclined portion, which matches the angle of the chamfer on the one surface side of the workpiece having the desired cross-sectional shape, and the inclined portion located on the one surface side of the workpiece that is attracted by the attracting member is located at a position that is closer to the front of the one surface side of the workpiece having the desired cross-sectional shape in a cross section along the rotation axis of the grindstone. and when the angle formed by the direction in which the inclined surface extends with respect to the surface on one side of the workpiece is smaller than the angle formed by the tapered shape of the suction member with respect to the surface on one side of the workpiece, the inclined surface has a length less than the length at which the inclined surface abuts against the tapered shape of the suction member in a state in which the tangent of the arc-shaped portion abuts against the end of the surface on one side of the workpiece at a position where the tangent of the arc-shaped portion extends at an angle that coincides with the angle of the tapered shape of the suction member, and when rough grinding is performed on the outer periphery of the surface on one side or the other side of the workpiece, and the grinding wheel are rotated, and the arc-shaped portion of the concave grinding portion of the grinding wheel is moved in a curved line relative to the workpiece by an angle calculated in advance in accordance with the movement conditions from the outer peripheral end surface of the workpiece toward the one surface or the other surface so that the rotation axis of the grinding wheel and the rotation axis of the workpiece are positioned in the same plane, and then the movement of the grinding wheel relative to the workpiece is stopped, and when precision grinding of the outer peripheral portion of the one surface side or the other surface side of the workpiece is performed, the concave grinding portion of the grinding wheel is moved in a curved line relative to the workpiece by an angle calculated in advance in accordance with the movement conditions. The arc-shaped portion of the cutting portion is moved in a curved line relative to the workpiece from the outer peripheral end surface of the workpiece toward the one surface or the other surface by an angle calculated in advance according to the movement conditions so that the rotation axis of the grinding wheel and the rotation axis of the workpiece are positioned in the same plane, and then the grinding wheel is moved linearly relative to the workpiece while maintaining the state in which the rotation axis of the grinding wheel and the rotation axis of the workpiece are positioned in the plane in which they were positioned during the curved movement.

[0028] A rotatable, disc-shaped grinding wheel having a concave grinding portion on its outer periphery, the cross-sectional shape of the concave grinding portion in a cross section along the rotation axis of the grinding wheel being concave recessed from the outer periphery toward the inner periphery, the grinding wheel having arc-shaped portions at least at both ends in the thickness direction, and a straight portion having a thickness equal to or greater than the thickness of the workpiece and performing grinding for at least one of reducing the diameter of the workpiece and smoothing an intermediate portion in the thickness direction of the outer periphery of the workpiece, is used to form a disc-shaped workpiece into a desired cross-sectional shape. Yet another workpiece machining method for machining a workpiece includes the steps of: arranging the workpiece and the grinding wheel parallel to each other; and, while rotating the grinding wheel and rotating the workpiece about a rotation axis parallel to the rotation axis of the grinding wheel, moving the grinding wheel relatively to the workpiece in accordance with movement conditions calculated based on a radius of curvature of the arc-shaped portion of the grinding wheel so that a contact portion between the concave grinding portion and the workpiece moves along the desired cross-sectional shape of the workpiece, the step of moving the grinding wheel relatively to the workpiece being performed on one side of the workpiece. While rotating the workpiece, the workpiece being attracted by an attracting member, and the grinding wheel, the arc-shaped portion of the concave grinding portion of the grinding wheel is moved in a curved line from the outer peripheral end face of the workpiece toward one surface by an angle calculated in advance in accordance with the movement conditions, thereby grinding the outer periphery of the one surface side of the workpiece to form a chamfered portion of the workpiece having the desired cross-sectional shape; moving the grinding wheel along the outer peripheral end face of the workpiece from the one surface side to the other surface side; and while rotating the workpiece, the circular arc-shaped portion of the concave grinding portion of the grindstone is moved in a curved line relatively to the workpiece from the outer peripheral end face of the workpiece toward the other surface by an angle calculated in advance in accordance with the movement conditions, thereby grinding the outer periphery on the other surface side of the workpiece to form a chamfered portion of the workpiece having the desired cross-sectional shape, wherein the planar shape of the attraction member is a circle with a radius smaller than the radius of the workpiece, and the outer peripheral portion of the circular attraction member has a tapered shape whose thickness decreases toward the outside, and the circular arc-shaped portion of the grindstone isThe radius of curvature of the arc-shaped portion of the grinding wheel is at least 10 times the thickness of the workpiece so that the grinding wheel can abut against the workpiece without creating a gap between the workpiece and the chamfered portion of the desired cross-sectional shape of the workpiece, and the arc-shaped portion located on the one surface side of the workpiece that is attracted by the attraction member is longer than the length of the chamfered portion of the one surface side of the workpiece that has the desired cross-sectional shape in a cross section along the rotation axis of the grinding wheel, and the arc-shaped portion is in contact with the workpiece at a position where the tangent of the arc-shaped portion extends at an angle that coincides with the angle of the tapered shape of the attraction member. and when rough grinding of the outer periphery of the one surface side or the other surface side of the workpiece is performed, the workpiece and the grindstone are rotated, and the arc-shaped portion of the concave grinding portion of the grindstone is moved in a curved line relative to the workpiece from the outer periphery end face of the workpiece toward the one surface or the other surface by an angle calculated in advance in accordance with the movement conditions, and then the relative movement of the grindstone with respect to the workpiece is stopped, and the outer periphery of the one surface side of the workpiece is ground. When performing precise grinding of the concave grinding portion, while rotating the workpiece and the grinding wheel, the outermost position on the one surface side in the thickness direction through which the workpiece passes when rotating is taken into consideration of a position error in the thickness direction that occurs when the workpiece is rotated, and the arc-shaped portion of the concave grinding portion of the grinding wheel is moved in a curved line relative to the workpiece from the outer peripheral end surface of the workpiece toward the one surface by an angle calculated in advance in accordance with the movement conditions, and then the movement is stopped, and the grinding wheel is moved in a curved line relative to the workpiece in the thickness direction at a position where the grinding wheel comes into contact with the slope of the chamfered portion on the one surface side of the workpiece. By rotating the workpiece at least one revolution while slowing down the rotation speed of the workpiece and adjusting the position of the workpiece, the one surface side of the workpiece is ground while canceling out the position error during rotation of the workpiece, and when performing precise grinding of the outer periphery of the other surface side of the workpiece, the workpiece and the grinding wheel are rotated, and the outermost position on the other surface side in the thickness direction through which the workpiece passes during rotation is used as a reference, and the arc-shaped portion of the concave grinding portion of the grinding wheel is moved from the outer periphery end surface of the workpiece toward the other surface,After the grinding wheel is moved in a curved line relative to the workpiece by an angle calculated in advance in accordance with the movement conditions, the movement is stopped, and the rotation speed of the workpiece is slowed down and rotated at least one revolution while adjusting the position in the thickness direction of the workpiece at a position where the grinding wheel contacts the slope of the chamfered portion on the other surface side of the workpiece, thereby grinding the other surface side of the workpiece while canceling out positional errors during rotation of the workpiece.

[0029] According to the present invention, it is possible to provide a workpiece processing device, a grinding wheel, and a workpiece processing method that can perform chamfering of a workpiece easily, efficiently, and with high precision, that has a simple mechanism for supporting and driving the workpiece and grinding wheel, and that can easily shape the grinding wheel.

[0030] 5 is a front view schematically showing a workpiece machining apparatus according to a first embodiment of the present invention; FIG. 6 is a cross-sectional view showing a grinding wheel of the workpiece machining apparatus shown in FIG. 1; FIG. 7 is a front view schematically showing one step of an example of a workpiece machining method according to the first embodiment of the present invention; FIG. 8 is a front view schematically showing a step subsequent to the step shown in FIG. 3A; FIG. 9 is a front view schematically showing a step subsequent to the step shown in FIG. 3B; FIG. 10 is a front view schematically showing a step subsequent to the step shown in FIG. 3C; FIG. 11 is an enlarged view showing the step shown in FIG. 12; FIG. 13 is an enlarged view showing a step subsequent to the step shown in FIG. 14; FIG. 15 is an enlarged view showing a step subsequent to the step shown in FIG. 16; FIG. 17 is a front view showing an example of a workpiece machined in the first embodiment of the present invention; FIG. 18 is an explanatory view for explaining the magnitude of positional deviation in the thickness direction and horizontal direction of the upper surface side of the workpiece; FIG. 19 is an explanatory view for explaining the magnitude of positional deviation in the thickness direction and horizontal direction of the lower surface side of the workpiece; FIG. 19 is a front view showing another example of a workpiece machined in the first embodiment of the present invention; FIG. 19 is a cross-sectional view showing an example of a grinding wheel of a conventional workpiece machining apparatus; FIG. 19 is a cross-sectional view showing in detail an example of the grinding wheel and grinding wheel support mechanism of the workpiece machining apparatus shown in FIG. 1; FIG. 19 is an explanatory view for explaining preferred dimensions of the grinding wheel of the first embodiment of the present invention; FIG. 19 is a cross-sectional view showing a grinding wheel of a workpiece machining apparatus according to a second embodiment of the present invention. FIG. 17 is an explanatory diagram for explaining preferred dimensions of the grinding wheel according to a second embodiment of the present invention. FIG. 18 is a front view schematically showing a workpiece machining apparatus according to a third embodiment of the present invention. FIG. 19 is a front view showing a workpiece machining apparatus according to a fourth embodiment of the present invention. FIG. 19 is a plan view of a workpiece and a grinding wheel for explaining an example of a workpiece machining method of the present invention. FIG. 19 is a plan view of a workpiece for explaining another example of a workpiece machining method of the present invention. FIG. 19 is an explanatory diagram for explaining an example of a workpiece machining method described using FIG.

[0031] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic front view of a workpiece machining apparatus 1 according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a grinding wheel 5 of the workpiece machining apparatus 1. The workpiece machining apparatus 1 is an apparatus that grinds a disk-shaped workpiece 2, such as a semiconductor wafer, a glass substrate, or a ceramic, and chamfers the outer periphery of the workpiece 2. The workpiece machining apparatus 1 is particularly suitable for chamfering high-hardness workpieces 2, including silicon (Si), silicon carbide (SiC), gallium nitride (GaN), gallium arsenide (GaAs), sapphire, and the like. However, the workpiece machining apparatus 1 can also be used to machine other types of workpieces.

[0032] The workpiece processing device 1 includes a workpiece support mechanism 4 that supports a disk-shaped workpiece 2 and rotates it about a rotation axis 3, and a grinding wheel support mechanism 7 that supports a disk-shaped grinding wheel 5 and rotates it about a rotation axis 6. As an example, the workpiece 2 is disk-shaped with a diameter of 50 to 300 mm and a thickness of approximately 1 mm or less, and the grinding wheel 5 is disk-shaped with a diameter of 100 to 200 mm and a thickness of approximately 20 to 60 mm. For convenience, the thickness of the workpiece 2 is illustrated as thicker in the drawings. The workpiece support mechanism 4 and the grinding wheel support mechanism 7 support the disk-shaped workpiece 2 and the disk-shaped grinding wheel 5 parallel to each other. The workpiece support mechanism 4 suction-holds one side surface 2b of the disk-shaped workpiece 2 with an attraction member 10, and can rotate the workpiece 2 about a rotation axis 3 that is located at the center of the planar shape of the workpiece 2 and perpendicular to the workpiece 2. Similarly, the grinding wheel support mechanism 7 can rotate the disk-shaped grinding wheel 5 around a rotation axis 6 that is located at the center of the planar shape of the grinding wheel 5 and is perpendicular to the grinding wheel 5. The rotation axis 3, which is the center of rotation of the workpiece 2 by the workpiece support mechanism 4, and the rotation axis 6, which is the center of rotation of the grinding wheel 5 by the grinding wheel support mechanism 7, are parallel to each other. The grinding wheel 5 and the workpiece 2 can be moved relatively toward or away from each other by the grinding wheel support mechanism 7 or the workpiece support mechanism 4. As an example, while rotating the grinding wheel 5, the grinding wheel support mechanism 7 can move the grinding wheel 5 in a direction toward or away from the workpiece 2 within a plane parallel to the grinding wheel 5 and the workpiece 2 (within a plane perpendicular to the rotation axis 3 and the rotation axis 6), and can also move the grinding wheel 5 in a direction toward or away from the workpiece 2 within a plane perpendicular to the grinding wheel 5 and the workpiece 2 (within a plane parallel to the rotation axis 3 and the rotation axis 6). Therefore, the grinding wheel 5 can approach and move away from the workpiece 2 in any direction within a plane including at least the rotation axes 3 and 6 by means of the grinding wheel support mechanism 7. The workpiece support mechanism 4 has a temperature adjustment mechanism 15 that generates a flow of liquid or gas to maintain a constant temperature of the rotation axis 3 of the workpiece support mechanism 4. Although not described in detail, the workpiece support mechanism 4 and the grinding wheel support mechanism 7 may be composed of a known suction table, rotary motor, movable stage, etc.A detailed and specific example of the configuration of the workpiece support mechanism 4 will be described later.

[0033] 2, the grinding wheel 5 of the workpiece processing device 1 has a base disk portion 5a serving as a base body, a concave grinding portion 5b located on the outer periphery of the base disk portion 5a, and a grinding portion 5g having a rectangular cross section that is arranged alongside the concave grinding portion 5b in the thickness direction. The base disk portion 5a is made of an alloy such as aluminum or stainless steel, and is provided with a straight mounting hole 5c extending in the thickness direction and through which the rotating shaft 6 is inserted, and a recess 5d for mounting on a holding portion (e.g., a flange portion) (not shown) of the grinding wheel support mechanism 7. The concave grinding portion 5b located on the outer periphery of the grinding wheel 5 is made of a metal-bonded grinding wheel or a resin-bonded grinding wheel, and the cross-sectional shape of the concave grinding portion 5b in a cross section along the rotation axis 6 of the grinding wheel 5 is concave, recessed from the radially outer (outer) side toward the radially inner (inner) side. It has arc-shaped portions 5e at both ends in the thickness direction, and a linear portion 5f with a thickness equal to or greater than the thickness of the workpiece 2 between the arc-shaped portions 5e at both ends. The concave grinding portion 5b does not include a convex portion protruding radially outward. The rectangular-cross-section grinding portion 5g is located further outward than the concave grinding portion 5b in the thickness direction of the grinding wheel 5, and its surface facing the workpiece 2 is linear and parallel to the thickness direction of the grinding wheel 5 in a cross section along the rotation axis 6. In Figure 2, the boundary between the arc-shaped portion 5e and the linear portion 5f is indicated by a virtual line (two-dot chain line).

[0034] A workpiece machining method using the workpiece machining apparatus 1 shown in FIG. 1 will now be described. FIGS. 3A to 3D are front views showing, in sequence, an example of this workpiece machining method. As shown in FIGS. 3A to 3D, the thickness of the grinding wheel 5 is much greater than the thickness of the workpiece 2. First, the workpiece 2 (e.g., a semiconductor wafer) is suction-held by the suction member 10 of the workpiece support mechanism 4 and rotated around the rotation axis 3. The workpiece 2 is rotated but does not move. The grinding wheel 5 attached to the grinding wheel support mechanism 7 is rotated around the rotation axis 6 by the grinding wheel support mechanism 7 and moved so that the outer periphery of the grinding wheel 5 abuts against the outer periphery of the workpiece 2. As an example, as shown in FIG. 3A, the grinding wheel 5 attached to the grinding wheel support mechanism 7 is positioned so that the rectangular cross-sectional grinding portion 5g faces the workpiece 2 suction-held by the suction member 10 of the workpiece support mechanism 4. While the workpiece 2 is rotated about the rotation axis 3 and the grinding wheel 5 is rotated about the rotation axis 6, the grinding wheel 5 is brought into contact with the outer periphery of the workpiece 2 and ground by the rectangular cross-sectional grinding portion 5g of the grinding wheel 5. In this manner, the outer periphery of the workpiece 2 is roughly ground (coarse grinding) using the rectangular cross-sectional grinding portion 5g, thereby reducing the diameter of the workpiece 2 to approach the desired size. The outer periphery of the workpiece 2 thus roughly ground by the rectangular cross-sectional grinding portion 5g is then brought into contact with the straight portion 5f of the concave grinding portion 5b of the grinding wheel 5 as shown in FIG. 3B, and more precisely ground (fine grinding) is performed to grind the workpiece 2 to the desired size (desired diameter).

[0035] Then, while the grinding wheel 5 is moved toward one surface of the workpiece 2 (above the workpiece 2 in the example shown in FIGS. 3A to 3D ), the rotation of the workpiece 2 and the rotation of the grinding wheel 5 are continued, and the grinding wheel 5 is moved relative to the workpiece 2 with the outer periphery of the grinding wheel 5 abutting against the outer periphery of one surface of the workpiece 2, as shown in FIG. 3C . Specifically, the grinding wheel 5 is gradually moved from near the center in the thickness direction of the workpiece 2 and radially inward toward the other surface of the workpiece 2 (the lower surface side in the example shown in FIGS. 3A to 3D ) and radially outward. As a result, the arc-shaped portion 5e of the upper concave grinding portion 5b of the grinding wheel 5 abuts against the edge on one surface (upper side) of the outer periphery of the workpiece 2, grinding and chamfering it, and a chamfered portion 2a is formed.

[0036] Once the chamfering of the upper edge of the outer periphery of the workpiece 2 is complete, the grinding wheel 5 is moved (raised) to one side (upward in the example shown in Figures 3A to 3D) so that the center of the grinding wheel 5 in the thickness direction faces the workpiece 2. Then, as shown in Figure 3D, the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5 is brought into contact with the outer periphery of the other side of the workpiece 2, and the grinding wheel 5 is raised while moving from the radially inner side to the radially outer side of the workpiece 2. In this way, the arc-shaped portion 5e of the lower concave grinding portion 5b of the rotating grinding wheel 5 is brought into contact with the outer periphery of the workpiece 2 to grind the workpiece 2, thereby chamfering the lower edge of the outer periphery of the workpiece 2 and forming the chamfered portion 2a. Finally, the workpiece 2 is positioned outside the concave grinding portion 5b of the grinding wheel 5, so that the grinding wheel 5 is no longer in contact with the workpiece 2, completing the chamfering of the workpiece 2. As shown in FIGS. 3A to 3D , the grinding wheel 5 moves back and forth (traverses) from a position facing the center of the workpiece 2 to one side and the other side (up and down) in the thickness direction of the workpiece 2 and the grinding wheel 5 to chamfer the upper and lower edges of the outer periphery of the workpiece 2. Both the upper and lower edges of the outer periphery of the workpiece 2 are chamfered by moving the grinding wheel 5 in the same direction in the radial direction of the workpiece 2 (moving from the inner side to the outer side in the radial direction of the workpiece 2). In this embodiment, the chamfered portions 2a on both sides are formed by the grinding wheel 5 moving in only one direction, from the inner side to the outer side in the radial direction of the workpiece 2. For example, as described in Patent Document 5, this embodiment allows grinding to be performed easily, quickly, and efficiently, compared to a method in which the grinding wheel and the workpiece move back and forth (traverses) relative to each other to grind not only the straight portion at the tip of the workpiece, but also the curved portion between the straight portion and the chamfered portion and the chamfered portion on both sides. In addition, since the concave grinding portion 5b of the grinding wheel 5 in this embodiment is mainly an arc-shaped curved surface, it is easy to calculate and design the curved surface shape according to the shape and dimensions of the chamfered portion 2a to be formed. Note that in some drawings, in order to make it easier to understand the desired cross-sectional shape of the workpiece 2, the shape of the chamfered portion 2a in a nearly completed state is shown even if the chamfered portion 2a is in the middle of being formed or has not yet been formed.

[0037] This workpiece machining method will be described in more detail with reference to FIGS. 4 to 6 . In the machining method of this embodiment, the movement conditions for the relative movement between the grinding wheel 5 and the workpiece 2 are calculated so that the contact portion between the concave grinding portion 5b of the grinding wheel 5 and the workpiece 2 moves along the desired cross-sectional shape of the workpiece 2. Because the dimensions of the grinding wheel 5 in this embodiment are known, the movement conditions for the relative movement between the grinding wheel 5 and the workpiece 2 are calculated based on the radius of curvature of the arc-shaped portions 5e located at both ends of the concave grinding portion 5b of the grinding wheel 5 in the thickness direction. The grinding wheel support mechanism 7 or the workpiece support mechanism 4 moves the grinding wheel 5 relative to the workpiece 2 in accordance with the movement conditions thus calculated. For example, the desired cross-sectional shape of the workpiece 2 is expressed as two-dimensional coordinates in a plane including the rotation axis 3 of the workpiece 2 and the rotation axis 6 of the grinding wheel 5, and the relative movement conditions between the grinding wheel 5 and the workpiece 2 are set so that the contact portion between the grinding wheel 5 and the workpiece 2 follows the points of each coordinate. In this manner, in this embodiment, the grinding wheel 5 and the workpiece 2 are moved relative to each other under NC (numerical control) control, thereby grinding the workpiece 2.

[0038] Specifically, the grinding wheel 5 abuts the rectangular-section grinding portion 5g of the grinding wheel 5 against the outer periphery of the workpiece 2 to perform rough grinding (rough grinding), and then, as shown in FIG. 4 , the straight portion 5f of the concave grinding portion 5b of the grinding wheel 5 abuts against the outer periphery of the workpiece 2 to perform more precise grinding (fine grinding) to reduce the diameter of the workpiece 2. The workpiece 2 is ground until the outer periphery of the workpiece 2 becomes approximately straight and the diameter of the workpiece 2 reaches a desired size. Then, as shown in FIG. 5 , the grinding wheel 5 is moved in the thickness direction relative to the workpiece 2 from a predetermined position P1 on one side (e.g., the upper side) of the workpiece 2 so that the corner of one side (e.g., the upper side) of the workpiece 2 slides in a curved line along the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5. By appropriately moving the grinding wheel 5 and the workpiece 2 relative to each other in the thickness direction and radial direction based on the movement conditions calculated in advance, the grinding wheel 5 follows a desired curved path relative to the workpiece 2. Then, when the grinding wheel 5 reaches a position P2 where the angle α from the starting point P1 of the relative movement from the outside to the inside in the radial direction of the workpiece 2 becomes a predetermined angle, the grinding wheel 5 is moved linearly relative to the workpiece 2 while maintaining a constant relative movement amount between the grinding wheel 5 and the workpiece 2. This forms a linear portion of the desired cross-sectional shape of the workpiece 2 (shown by the two-dot chain line). The angle α is an angle measured from the inner periphery of the workpiece 2 within a plane including the rotation axis 3 of the workpiece 2 and the rotation axis 6 of the grinding wheel 5. The grinding wheel 5 then moves relatively to the outside of one surface in the thickness direction of the workpiece 2 and comes out of contact with the workpiece 2, completing grinding of one surface of the workpiece 2. On the other surface of the workpiece 2, as shown in FIG. 6, grinding of the other surface of the workpiece 2 is performed by performing an operation that is essentially the upside-down operation of the operation on one surface of the workpiece 2 shown in FIG. 5.

[0039] In reality, the difference in size between the grinding wheel 5 and the workpiece 2 is much larger than shown in FIGS. 4 to 6 (for example, the radius of curvature of the arc-shaped portion 5 e of the grinding wheel 5 is several tens of times the thickness of the workpiece 2), and the portion of the arc-shaped portion 5 e of the grinding wheel 5 that contacts the outer peripheral surface of the workpiece 2 may be substantially linear. For example, when the grinding wheel 5 moves and the movement angle α reaches a predetermined value (see FIGS. 5 and 6 ), the gap between the arc-shaped portion 5 e of the grinding wheel 5 and the desired shape of the chamfered portion 2 a to be formed on the workpiece 2 (shown by the two-dot chain line in FIGS. 5 and 6 ) may be negligibly small, and the grinding wheel may contact the workpiece 2 so that the entire chamfered portion 2 a of the workpiece 2 can be ground into the desired shape. In this case, it may be possible to stop the movement of the grinding wheel 5 when the movement angle α reaches a predetermined value and omit the subsequent step of moving the grinding wheel 5 linearly relative to the workpiece 2. When performing more precise grinding, it is preferable to perform a step of moving the grinding wheel 5 in a curved line until the movement angle α reaches a predetermined value, and then moving the grinding wheel 5 linearly relative to the workpiece 2. However, when performing relatively rough grinding as a preliminary step to precise grinding, the work may be simplified by omitting the step of moving the grinding wheel 5 in a curved line until the movement angle α reaches a predetermined value, and then moving the grinding wheel 5 linearly relative to the workpiece 2. In this embodiment, the radius of curvature of the arc-shaped portion 5e of the grinding wheel 5 is at least 10 times the thickness of the workpiece 2 so that the arc-shaped portion 5e of the grinding wheel 5 abuts against the workpiece 2 without creating a substantial gap between the arc-shaped portion 5e and the chamfered portion 2a of the workpiece 2 having the desired cross-sectional shape.

[0040] As described above, in this embodiment, by moving the grinding wheel 5 and the workpiece 2 relatively in accordance with the movement conditions calculated in advance, the contact portion between the grinding wheel 5 and the workpiece 2 follows a movement trajectory calculated based on the desired cross-sectional shape of the workpiece 2. As a result, the workpiece 2 can be formed into the desired cross-sectional shape. When machining a different type of workpiece 2, the movement conditions for machining the new workpiece 2 are calculated to match the desired cross-sectional shape of the workpiece 2 to be machined. At this time, the movement conditions are calculated based on the radius of curvature of the arc-shaped portion 5e of the grinding wheel 5, so that workpieces 2 of various shapes can be accurately machined using the same grinding wheel 5.

[0041] The effects of this embodiment will be described. In the conventional machining methods described in Patent Documents 6 and 10, due to structural reasons, it is difficult to use a very large (large-diameter) grinding wheel, so machining must be performed using a small (small-diameter) grinding wheel. As a result, the grinding wheel has a short lifespan, and the grinding wheel needs to be replaced or reshaped frequently. However, in this embodiment, the grinding wheel 5 and the grinding wheel support mechanism 7 are less likely to interfere with other components, specifically the workpiece support mechanism 4, so structural constraints are reduced and a large (large-diameter) grinding wheel 5 can be used to machine the workpiece 2. Therefore, the grinding wheel 5 has a long lifespan and the grinding wheel needs to be replaced or reshaped less frequently. Furthermore, in the machining methods described in Patent Documents 6 and 10, the rotation direction of the grinding wheel and the direction of movement relative to the workpiece are substantially the same (both are in the thickness direction of the workpiece 2). Therefore, if there are large irregularities on the outer periphery of the grinding wheel, the rotation of the grinding wheel is likely to cause linear scratches on the outer periphery of the workpiece along the rotation direction (thickness direction of the workpiece). While rotating, the grinding wheel moves relative to the workpiece in the same direction as the rotation, i.e., a direction substantially parallel to the linear scratches, so the linear scratches tend to remain. The portion of the grinding wheel that created the linear scratches on the outer peripheral surface of the workpiece (the large uneven portion) moves relatively in the thickness direction of the workpiece while maintaining its circumferential position. Therefore, there is a possibility that portions of the workpiece that do not come into contact with the large uneven portion and are not ground as deeply as the linear scratches remain. As a result, the linear scratches tend to remain even when the grinding wheel moves. Although the workpiece rotates in a direction perpendicular to the rotation direction of the grinding wheel, the length of the circumferential movement of the workpiece due to its rotation is much longer than the length of relative movement between the grinding wheel and the workpiece in the thickness direction of the workpiece. Because the grinding wheel grinds the entire circumference of the workpiece and moves relative to the workpiece in the thickness direction of the workpiece, in order to prevent the workpiece processing time from becoming too long, it is necessary to ensure that the speed at which the grinding wheel moves in the thickness direction of the workpiece relative to the workpiece is not too slow. The part of the workpiece that comes into contact with the grinding wheel has a narrow width in the circumferential direction of the workpiece, and in order to prevent the speed at which the grinding wheel moves in the thickness direction of the workpiece relative to the workpiece from slowing down, it is necessary to increase the rotational speed of the workpiece (circumferential movement speed) and shorten the time required for the grinding wheel to come into contact with and grind the entire circumference of the workpiece.In this way, by increasing the rotation speed of the workpiece, the surface roughness of the workpiece after grinding increases even if the workpiece and the grinding wheel rotate in mutually perpendicular directions. In contrast, in this embodiment, the rotation direction of the grinding wheel 5 and the direction of relative movement with respect to the workpiece 2 are substantially perpendicular. The rotation direction of the grinding wheel 5 is the circumferential direction of the workpiece 2, and the relative movement direction is the thickness direction of the workpiece 2. If the grinding wheel 5 has large irregularities on its outer periphery, the rotation of the grinding wheel 5 will cause linear scratches along the circumferential direction on the outer periphery of the workpiece 2. Since the grinding wheel 5 moves relative to the workpiece 2 in a direction perpendicular to the rotation direction, i.e., a direction substantially perpendicular to the linear scratches, linear scratches are unlikely to remain. The portion of the grinding wheel 5 that caused the linear scratches on the outer periphery of the workpiece 2 (large irregularities) moves in a direction perpendicular to the linear scratches while rotating circumferentially, so these large irregularities sequentially come into contact with almost the entire outer periphery of the workpiece 2. Therefore, almost the entire outer periphery of the workpiece 2 is ground by these large irregularities to a depth comparable to the linear scratches. In this way, since the rotation direction of the grinding wheel 5 and the direction of relative movement with respect to the workpiece 2 are substantially perpendicular, linear scratches on the outer peripheral surface of the workpiece 2 are easily removed and the workpiece 2 is smoothed. Note that with this configuration, even if the rotation speed of the workpiece 2 is fast, the rotation direction of the grinding wheel 5 (circumferential direction of the workpiece 2) and the direction of relative movement of the grinding wheel 5 (thickness direction of the workpiece 2) are perpendicular, and the relative movement distance is short, so even if the grinding wheel 5 moves very slowly relative to the workpiece 2 in the thickness direction, the processing time does not become very long. Therefore, by relatively slowing the relative movement speed of the grinding wheel 5 in the thickness direction of the workpiece 2 and sufficiently grinding the entire circumference of the workpiece 2, the surface roughness of the workpiece after grinding can be improved.

[0042] In the conventional processing method described in Patent Document 5, grinding is performed by moving the workpiece relatively along the outer shape of the grinding wheel. Therefore, the shape of the processed workpiece is determined by the outer shape of the grinding wheel (especially the shape and angle of the curved or linear inclined surface of the grinding wheel). Therefore, changing the grinding wheel is necessary to grind workpieces of different shapes. In contrast, in this embodiment, the relative movement of the grinding wheel 5 and the workpiece 2 is not performed along the outer shape of the grinding wheel 5, but is performed according to movement conditions calculated taking into account the radius of curvature of the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5. Therefore, when grinding workpieces of different shapes, it is not necessary to replace the grinding wheel 5; instead, the movement conditions can be changed. In other words, workpieces of various shapes can be ground using the same grinding wheel 5 without replacing the grinding wheel 5. The movement conditions are calculated based on the radius of curvature of the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5, etc., and the relative movement of the grinding wheel 5 and the workpiece 2 is numerically controlled based on these movement conditions, resulting in high machining accuracy. As described above, according to this embodiment, it is possible to form workpieces 2 of various shapes using the same grinding wheel 5, and further, it is possible to achieve many excellent effects, such as good processing accuracy and a long life for the grinding wheel 5.

[0043] The machining apparatus and machining method of this embodiment can accurately form both a so-called T-shaped workpiece 2 whose outer periphery is formed by a pair of arc-shaped portions and a straight portion connecting them, as shown in Fig. 7A, and a so-called R-shaped workpiece 2 whose outer periphery is semicircular, as shown in Fig. 8. In the case of the T-shaped workpiece 2 shown in Fig. 7A, machining is performed according to movement conditions determined by calculation based on the radii of curvature R1, R2 of the pair of arc-shaped portions on the outer periphery, the lengths Y1, Y2 of the linear inclined surface portions connecting each arc-shaped portion, the angles θ1, θ2 of these inclined surface portions with respect to the surface of the workpiece 2, the length C0 of the straight portion between the pair of arc-shaped portions, and the radius of curvature of the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5 (not shown in Fig. 7A). In the case of the R-shaped workpiece 2 shown in Fig. 8, machining is performed according to movement conditions determined by calculation based on the radius R of the semicircular portion on the outer periphery, the lengths Y1 and Y2 of the linear inclined surface portions connecting to both sides of the semicircular portion, the angles θ1 and θ2 of these inclined surface portions relative to the surface of the workpiece 2, and the radius of curvature of the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5, which is not shown in Fig. 8. In this way, both the T-shaped workpiece 2 shown in Fig. 7A and the R-shaped workpiece 2 shown in Fig. 8 can be machined with high precision by numerical control in accordance with movement conditions determined by calculation based on the dimensions of each portion of the desired cross-sectional shape shown in the figure and the radius of curvature of the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5.

[0044] In this embodiment, the grinding wheel support mechanism 7 adjusts the position of the grinding wheel 5 in the radial direction of the workpiece 2 before the start of chamfering, i.e., the position where the grinding wheel 5 starts to contact the workpiece 2, and the position of the grinding wheel 5 at the end of chamfering, i.e., the position where the grinding wheel 5 stops contacting the workpiece 2, thereby adjusting the size of the chamfered portion 2a. Furthermore, taking into consideration the size of the chamfered portion 2a thus adjusted and the speed at which the grinding wheel 5 grinds the workpiece 2, the grinding wheel support mechanism 7 adjusts the speed at which the grinding wheel 5 is raised or lowered and the speed at which the grinding wheel 5 is moved in the radial direction of the workpiece 2, thereby adjusting the angle, shape, etc. of the chamfered portion 2a of the workpiece 2. Furthermore, since the contact angle of the grinding wheel 5 with the workpiece 2 changes depending on which part of the curved portion on the outer periphery of the grinding wheel 5 is brought into contact with the workpiece for grinding, the angle, shape, etc. of the chamfered portion 2a of the workpiece 2 can be adjusted. In this way, the desired shape and dimensions of the chamfered portion 2a of the workpiece 2 can be achieved mainly by controlling the movement of the grinding wheel 5 by the grinding wheel support mechanism 7. For this reason, it is preferable that the grindstone support mechanism 7 drives the grindstone 5 by numerical control (NC control).

[0045] The grinding wheel 5 of this embodiment has a concave grinding portion 5b, which performs grinding such as chamfering of the workpiece 2. This allows for stable and smooth grinding, while also reducing the cost and extending the life of the grinding wheel 5. For example, as in the configuration described in Patent Document 11 (not shown), when a grinding wheel has a convex grinding portion and uses this convex grinding portion to grind the workpiece, grinding is performed while the center (rotation axis) of the grinding wheel and the center (rotation axis) of the workpiece are moved relative to each other so that they approach each other while the convex grinding portion is in contact with the workpiece. This relative movement is in the direction in which the grinding wheel and the workpiece collide, resulting in large impacts and vibrations during grinding, and large loads on both the grinding wheel and the workpiece. Furthermore, grinding wheels with convex grinding portions are relatively heavy and have a large moment of inertia. In contrast, the grinding wheel 5 of this embodiment has a concave grinding portion 5b. With the concave grinding portion 5b in contact with the workpiece 2, grinding is performed while the center of the grinding wheel 5 (rotation axis 6) and the center of the workpiece 2 (rotation axis 3) are moved relative to each other in a direction away from each other. This reduces impact and vibration during grinding compared to relative movement in the direction of collision between the grinding wheel 5 and the workpiece 2, reduces the load on the grinding wheel 5 and the workpiece 2, and produces a clean ground surface. Furthermore, compared to the convex grinding portion, the concave grinding portion 5b, which has a similar size to the portion actually used for grinding, can be made smaller and lighter, and its moment of inertia can be reduced. This also contributes to reducing vibration during grinding. In this configuration, grinding the workpiece 2 using the concave grinding portion 5b of the grinding wheel 5 involves less vibration and load, resulting in slower deterioration and a longer life. This also reduces the manufacturing cost of the grinding wheel 5.

[0046] For example, when grinding the workpiece by using the convex grinding portion of the grinding wheel, such as in the configuration described in Patent Document 11, the contact area between the convex grinding portion and the workpiece is almost point contact. However, when grinding the workpiece 2 by using the concave grinding portion 5b of the grinding wheel 5, as in this embodiment, the contact area between the concave grinding portion 5b and the workpiece 2 is surface contact, allowing for efficient and stable grinding and resulting in a clean ground surface.

[0047] Furthermore, when a grinding wheel has a convex grinding portion and a workpiece is ground using this convex grinding portion, even if grinding water (coolant) is supplied to the contact area between the grinding wheel and the workpiece to ensure smooth grinding, the grinding water is difficult to retain at the contact area between the grinding wheel and the workpiece. Therefore, it is not easy to perform efficient and smooth grinding, and a large amount of grinding water is required. In contrast, in this embodiment, the grinding wheel 5 has a concave grinding portion 5b, and when the workpiece 2 is ground using this concave grinding portion 5b, the grinding water supplied to the contact area between the grinding wheel 5 and the workpiece 2 is retained at the contact area between the grinding wheel 5 and the workpiece 2 inside the concave grinding portion 5b. Therefore, efficient and smooth grinding can be easily performed, using a small amount of grinding water, and smooth grinding can be performed without clogging, excessive friction, or heat generation.

[0048] As described above, the grinding wheel 5 of this embodiment has numerous advantages due to its concave grinding portion 5b rather than a convex grinding portion. While grinding wheels with concave grinding portions have been used in the past, these conventional concave grinding portions have a groove, a so-called formed groove 16a, whose shape is complementary to the desired shape of the workpiece after grinding, as shown in FIG. 9 . In a machining method using a grinding wheel 16 with a conventional formed groove 16a, wear and damage are likely to occur in a specific portion of the grinding wheel 16, such as portion P3 on the inner circumferential surface of the formed groove 16a, where the workpiece 2 first contacts. When machining a large number of workpieces 2, wear and damage to portion P3 can occur, changing the shape of the formed groove 16a. Therefore, machining the workpiece 2 using that grinding wheel 16 results in reduced machining accuracy. In this case, the grinding wheel 16 must be replaced or reshaped. In contrast, in this embodiment, the grinding wheel 5 has a concave grinding portion 5b that is much larger than the workpiece 2. Because various portions of the concave grinding portion 5b of the grinding wheel 5 contact and grind the workpiece 2, no specific portion is particularly susceptible to wear or damage. Therefore, the life of the grinding wheel 5 is relatively long. Furthermore, in this embodiment, a grinding portion 5g with a rectangular cross section is provided in addition to the concave grinding portion 5b. This rectangular cross section grinding portion 5g is used to perform rough grinding to bring the workpiece 2 closer to the desired size. This prevents excessive wear and damage to the linear portion 5f of the concave grinding portion 5b, thereby extending the life of the grinding wheel 5. However, the rectangular cross section grinding portion 5g is not a required component of the present invention. It is also possible to configure the grinding wheel 5 so that grinding to the desired diameter is performed using only the linear portion 5f of the concave grinding portion 5b.

[0049] In the above-described embodiment, the grinding wheel support mechanism 7 rotates and moves the grinding wheel 5, and the workpiece support mechanism 4 rotates but does not move the workpiece 2. However, the present invention is not limited to such a configuration. That is, the grinding wheel support mechanism 7 can rotate but not move the grinding wheel 5, and the workpiece support mechanism 4 can rotate the workpiece 2 and move the workpiece 2 by numerical control. In this case, the workpiece support mechanism 4 can move the workpiece 2 in both directions toward and away from the grinding wheel 5 within a plane parallel to the grinding wheel 5 and workpiece 2 (within a plane perpendicular to the rotation axis 3 and rotation axis 6). The workpiece support mechanism 4 can also move the workpiece 2 in both directions toward and away from the grinding wheel 5 within a plane perpendicular to the grinding wheel 5 and workpiece 2 (within a plane parallel to the rotation axis 3 and rotation axis 6). Therefore, the grinding wheel support mechanism 7 allows the workpiece 2 to approach and move away from the grinding wheel 5 in any direction within a plane including at least the rotation axes 3 and 6. Even with this configuration, the workpiece 2 and the grinding wheel 5 can be moved relative to each other so that they have the same positional relationship as in each process shown in Figures 3 to 6, and processing similar to the processing method shown in Figures 3 to 6 can be performed.

[0050] In this embodiment, the grinding wheel 5 and the workpiece 2 are rotated in the same or opposite directions rather than in directions perpendicular to each other, so that a synergistic effect is produced between the rotation of the grinding wheel 5 and the rotation of the workpiece 2, and the rotation speed of the grinding wheel 5 itself does not need to be very high. Therefore, the grinding wheel support mechanism 7 does not need to be capable of high-speed rotation, which simplifies the structure and reduces costs. Furthermore, because grinding is performed while the workpiece 2 is rotated parallel to the grinding wheel 5, the surface roughness of the chamfered portion of the workpiece 2 can be reduced.

[0051] According to this embodiment, the grinding wheel 5 is arranged parallel to the workpiece 2, allowing the grinding wheel 5 to be large without interfering with the workpiece support mechanism 4. This allows the outer periphery of the workpiece 2 to be formed into any cross-sectional shape using a large grinding wheel 5 without complicating the configuration of the workpiece processing apparatus 1, including the grinding wheel support mechanism 7. Furthermore, using a large grinding wheel 5 improves processing efficiency and shortens processing time, and allows processing to be performed using a wide area of ​​the outer periphery of the grinding wheel 5, thereby extending the life of the grinding wheel 5. Furthermore, when processing is performed using a grinding wheel 16 having a groove 16a (formed groove) formed in a shape corresponding to the shape of the finished workpiece 2, the inner periphery of the groove 16a (particularly the portion of the inclined surface P3) that abuts against the edge of the workpiece 2 before chamfering is prone to wear and damage. However, in this embodiment, the grinding wheel 5 is not configured so that only one specific point on the grinding wheel 5 continuously abuts against the edge of the workpiece 2 before chamfering, making the grinding wheel 5 less likely to be damaged and having a longer life.

[0052] When the workpiece 2 is inserted into the formed groove 16a provided in the grinding wheel 16 and processed, a chamfer of a specific shape and size can be formed, but to form a chamfer of a different shape and size, it is necessary to replace the grinding wheel 16 with one having a different groove 16a. However, according to this embodiment, the grinding wheel 5 having the concave grinding portion 5b is moved relative to the workpiece 2 to perform the chamfering, so the shape and size of the chamfered portion 2a formed can be changed by changing the path of movement of the grinding wheel 5 through numerical control. In other words, a single grinding wheel 5 can be used to form chamfered portions 2a of various shapes and sizes.

[0053] FIG. 10 shows a detailed configuration example of the grinding wheel 5 and grinding wheel support mechanism 7 shown schematically in FIGS. 1 and 2 . The grinding wheel 5 of this modified example includes a base disk portion 5a made of, for example, a metal, a concave grinding portion 5b made of a resin-bonded grinding wheel located on the outer periphery of the base disk portion 5a, and a grinding portion 5g having a rectangular cross section that is aligned with the concave grinding portion 5b in the thickness direction. The base disk portion 5a is made of an alloy such as aluminum or stainless steel and has a mounting hole 5c through which the rotating shaft 6 is inserted and a recess 5d. The concave grinding portion 5b is recessed from the outer periphery to the inner periphery, and includes arc-shaped portions 5e at both ends in the thickness direction and a linear portion 5f located between the arc-shaped portions 5e and having a thickness equal to or greater than the thickness of the workpiece 2. The rectangular cross-sectional grinding portion 5g is located further outward than the concave grinding portion 5b in the thickness direction of the grinding wheel 5, and the surface facing the workpiece 2 is linear and parallel to the thickness direction of the grinding wheel 5.

[0054] The grinding wheel support mechanism 7 shown in FIG. 10 includes a case 7a, a rotary bearing 7b, a spindle 7c, a flange 7d, and a bolt 7e. The spindle 7c is rotatably supported by the rotary bearing 7b disposed within the case 7a. The flange 7d is attached to the tip of the spindle 7c, which protrudes outward from the case 7a, and the flange 7d is fixed to the spindle 7c by a bolt 7e. The case 7a is inserted into the recess 5d of the grinding wheel 5, and the mounting hole 5c of the grinding wheel 5 is fixed to the flange 7d. When the spindle 7c is rotated by a driving means (not shown), the flange 7d and the grinding wheel 5 rotate integrally with the spindle 7c. In other words, the spindle 7c serves as the rotation axis 6 of the grinding wheel support mechanism 7. The grinding wheel 5 is supported so that its center of gravity is located between the flange 7d, where the grinding wheel 5 is attached, and the rotary bearing 7b, which supports the spindle 7c. In this way, the center of gravity of the grinding wheel 5 is located between the mounting position of the grinding wheel 5 (flange portion 7d) and the rotation bearing portion 7b, so that the support and rotation of the grinding wheel 5 are stable.

[0055] In this embodiment, a two-stage grinding process is performed: grinding to reduce the radius of the workpiece 2, and grinding to chamfer both sides of the outer periphery of the workpiece 2 to form the workpiece 2 into a desired cross-sectional shape. Generally, the former grinding is rough grinding, and the latter grinding is precision grinding. Precision grinding and rough grinding are relative terms, and precision grinding refers to grinding that has better shape and dimensional accuracy and reduces the surface roughness of the ground surface compared to rough grinding. In this embodiment, the grinding wheel 5 is provided, on the outer periphery of the base disk portion 5a, with a concave grinding portion (precision grinding portion) 5b that is mainly used for grinding to form the workpiece 2 into a desired cross-sectional shape, and a cross-sectionally rectangular grinding portion (coarse grinding portion) 5g that is mainly used for grinding to reduce the radius of the workpiece 2.

[0056] In this embodiment, the unmachined workpiece 2 is set on the workpiece support mechanism 4 and rotated. The grinding wheel 5 attached to the grinding wheel support mechanism 7 is rotated around the rotation axis 6 (spindle 7c) while the rectangular cross-sectional grinding portion 5g is brought into contact with the outer periphery of the workpiece 2, as shown in FIG. 3A. This roughly grinds the outer periphery of the workpiece 2, resulting in the desired outer diameter. Next, as shown in FIG. 3B, the linear portion 5f of the concave grinding portion 5b of the grinding wheel 5 is brought into contact with the outer periphery of the workpiece 2, thereby precisely grinding the outer periphery of the workpiece 2 and smoothing the middle portion of the outer periphery in the thickness direction of the workpiece 2. Then, as shown in FIGS. 3C and 3D, the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5 is brought into contact with the outer periphery of the workpiece 2, thereby chamfering the edges on both sides of the workpiece 2 and forming the workpiece 2 into the desired cross-sectional shape. In this embodiment, the grinding portion 5g having a rectangular cross section is a portion where the grinding stone has a coarse grain size, and the grinding portion 5b having a concave shape is a portion where the grinding stone has a fine grain size, and where more precise grinding is performed than in the grinding performed by the grinding portion 5g having a rectangular cross section to reduce the radius of the workpiece 2. In this embodiment, in addition to the effects described above, when chamfering the workpiece 2 by a two-stage grinding process, both steps can be easily performed using only a single grinding stone 5, and the effect of a simple manufacturing process and low cost is obtained.

[0057] Generally, when chamfering a workpiece 2 such as a semiconductor wafer, the outer peripheral surface of the workpiece 2 is ground with a grinding wheel to reduce the radius, and unnecessary portions of the workpiece 2 are removed to achieve the desired size, while the outer shape is adjusted and centering is performed. Then, a chamfered portion 2a is formed on the workpiece 2 with a grinding wheel. If these grinding operations are performed using a single concave grinding portion, the previous grinding operation (rough grinding) to reduce the radius of the workpiece 2 is performed by primarily abutting the workpiece 2 with a portion of the concave grinding portion of the grinding wheel near the center in the thickness direction. The subsequent grinding operation (precision grinding) to form the chamfered portion 2a is performed by abutting the arc-shaped portions at both ends of the concave grinding portion in the thickness direction against the workpiece 2. Typically, the grinding operation to reduce the radius of the workpiece 2 requires a larger grinding volume (ground volume) than the grinding operation to form the chamfered portion 2a. Therefore, the portion of the concavely ground portion near the center in the thickness direction is subject to more severe wear than the arc-shaped portions at both ends in the thickness direction, causing the overall shape of the concavely ground portion to collapse. As a result, the machining accuracy of the workpiece 2 may decrease. In contrast, in this embodiment, grinding to reduce the radius of the workpiece 2 is performed primarily by the rectangular-cross-section grinding portion 5g, grinding to smooth the outer peripheral surface of the workpiece 2 with the reduced radius is performed by the linear portion 5f of the concavely ground portion 5b, and grinding to form the chamfered portion 2a of the workpiece 2 is performed by the arc-shaped portion 5e of the concavely ground portion 5b. In other words, grinding to reduce the radius of the workpiece 2, grinding to smooth the outer peripheral surface of the workpiece 2, and grinding to form the chamfered portion 2a can be performed by different portions of the grinding wheel 5. The shape and dimensions of the rectangular-cross-section grinding portion 5g and the straight-line portion 5f and arc-shaped portion 5e of the concave grinding portion 5b can be controlled independently, and even if the wear amounts of each are different, good machining can be achieved by appropriately adjusting the machining conditions. Furthermore, the arc-shaped portion 5e of the concave grinding portion 5b is primarily used for grinding to form the chamfered portion 2a, and wear occurs relatively evenly, without a single portion (e.g., a portion near the center in the thickness direction) experiencing significantly greater wear than other portions. Therefore, the shape of the concave grinding portion 5b of the grinding wheel does not change significantly, preventing a decrease in the machining accuracy of the workpiece 2.Although the grinding portion 5g having a rectangular cross section is significantly worn, the surface facing the workpiece 2 is a simple straight line parallel to the thickness direction of the grinding wheel 5, so even if wear occurs, the processing accuracy does not decrease significantly.

[0058] Although not shown, the grinding wheel 5 can be fixed to the spindle 7c constituting the rotating shaft 6 and rotatably supported together with the spindle 7c by inserting the tapered portion of the spindle 7c constituting the rotating shaft 6 into a tapered mounting hole 5c provided in the grinding wheel 5 and attaching a fixing member such as a nut to the tip of the spindle 7c protruding from the base disk portion 5a without using a flange portion. In this way, in the grinding wheel support mechanism 7 of this embodiment, the grinding wheel 5 can be stably fixed to the spindle 7c constituting the rotating shaft 6 without using a flange portion, and further, eccentricity of the grinding wheel 5 with respect to the rotating shaft 6 (spindle 7c) can be suppressed.

[0059] As shown in Figures 1 and 3A-3D, the workpiece support mechanism 4 of this embodiment has an attraction member 10 that attracts only one side (e.g., the vertically lower surface) 2b of the workpiece 2. Therefore, as shown in Figures 3B, 3C, and 3D, when grinding the workpiece 2 for chamfering using the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5, the attraction member 10 must avoid contact with the arc-shaped portion 5e. The planar shape of the attraction member 10 is a circle with a radius smaller than the radius of the workpiece 2, and the outer periphery of the circular attraction member 10 has a tapered shape 10a that becomes thinner toward the outside. When the radius r1 of the attraction member 10 is expressed in terms of the radius r2 of the desired cross-sectional shape of the workpiece 2 and the thickness t of the workpiece 2, it is preferable that the relationship r2-10t≦r1≦r2-5t be satisfied. When the angle θ1 of the tapered shape 10a of the attraction member 10 is expressed in terms of the angle θ2 of the chamfered portion 2a of the desired cross-sectional shape of the workpiece 2, it is preferable that θ2-10≦θ1≦θ2+5. The length of the arc-shaped portion 5e located on the side of the surface 2b of the workpiece 2 that is attracted by the attraction member 10 (e.g., the lower vertical surface) is less than the length at which the arc-shaped portion 5e abuts against the tapered shape 10a of the attraction member 10 in a state where the tangent to the arc-shaped portion 5e contacts the end of the workpiece 2 on the side of the surface 2b (e.g., the lower vertical surface) at a position (point A in FIG. 11 ) where the tangent to the arc-shaped portion 5e extends at an angle θ3 that coincides with the angle θ3 of the tapered shape 10a of the attraction member 10 in a cross section along the rotation axis 6 of the grinding wheel 5. In the state shown in FIG. 11 , the tangent to the arc-shaped portion 5e at point A is inclined by θ3 from the horizontal and is parallel to the lower surface of the tapered shape 10a of the suction member 10. If the arc-shaped portion 5e extended to point D where the lower surface of the tapered shape 10a of the suction member 10 abuts the arc-shaped portion 5e, further grinding would be impossible. Therefore, the length of the arc-shaped portion 5e is less than the length to point D. The angle of inclination of the tangent at point D from the horizontal is θ4, and the radius of curvature of the arc-shaped portion 5e is r. FIG. 11 shows angles θ3 and θ4, respectively, as the angles formed by the radii passing through points A and D of the arc-shaped portion 5e (radii perpendicular to the tangent at each point) and the vertical direction. Here, angle θ3 is known as the dimension of the tapered shape 10a of the suction member 10.Therefore, the relationship between the radius of curvature r of the arc-shaped portion 5e of the grinding wheel 5 and the angle θ4 indicating the limit point of the length of the arc-shaped portion 5e is expressed as follows: When a line is drawn that is parallel to the tangent at point A of the arc-shaped portion 5e, i.e., perpendicular to the radius that passes through point A and passes through point D, the distance from that line to point A along the radius that passes through point A is defined as r'. rcos(θ3-θ4)=r-r' θ3-θ4=cos -1 [(r-r') / r] θ4=θ3-cos -1 [(r-r') / r] By such a calculation, it is possible to set the condition for the arc-shaped portion 5e to have a length less than the length at which it abuts against the tapered shape 10a of the suction member 10, when the arc-shaped portion 5e is in contact with the end portion on the underside of the workpiece 2 at a position where the tangent to the arc-shaped portion 5e extends at an angle θ3 that matches the angle θ3 of the tapered shape 10a of the suction member 10.

[0060] In this calculation to determine the angle θ4, the distance r' from a line parallel to the tangent at point A of the arc-shaped portion 5e (perpendicular to the radius passing through point A) passing through point D to point A along the radius passing through point A is used. This distance r' can be determined as follows. Here, the difference between the radius of the workpiece 2 having the desired cross-sectional shape and the radius of the suction member 10 is defined as L. This distance L is then divided into thirds, and the length on the outer periphery side of the intersection point with the radius passing through point A of the arc-shaped portion 5e is defined as R2. This corresponds to the radius of curvature of the lower curved portion of the desired cross-sectional shape of the workpiece 2 shown in Figures 7A and 8. The portion remaining after subtracting the length R2 from the distance L is then divided into two parts, centered on the intersection point with a line parallel to the tangent at point A of the arc-shaped portion 5e (perpendicular to the radius passing through point A) passing through point D, and the length of the inner periphery portion is defined as x1, and the length of the outer periphery portion is defined as x2. The distance from the intersection point separating the portions of length x1 and length x2 to the underside of the workpiece 2 is defined as B2. The distance from the surface of the suction member 10 that contacts the underside of the workpiece 2 to the tapered shape 10a below it is defined as T. The distance from the starting point of the arc-shaped portion 5e on the underside of the desired cross-sectional shape of the workpiece 2 shown in Figures 7A and 8 to the underside of the workpiece 2 is defined as B2. x1 tan θ3 = T + B2 x1 = (T + B2) / tan θ3 x2 = L - R2 - x1 = L - R2 - (T + B2) / tan θ3 r' = R2 + x2 sin θ3 = R2 + [L - R2 - (T + B2) / tan θ3] sin θ3 By substituting r' determined in this way into the equation for determining angle θ4 described above, angle θ4 for determining the upper limit of the length of arc-shaped portion 5e can be determined based on radius of curvature R2 and distance B2, which are the dimensions of the desired cross-sectional shape of workpiece 2 shown in Figures 7A and 8, distance T and angle θ3 of tapered shape 10a, which are known dimensions of attraction member 10, distance L determined from the dimensions of the desired cross-sectional shape of workpiece 2 and the known dimensions of attraction member 10, and radius of curvature r of arc-shaped portion 5e of grinding wheel 5.

[0061] 7A and 8, the length of the arc-shaped portion 5e required to form the length A2 of the chamfered portion 2a of the workpiece 2 when projected in the horizontal direction is calculated. The angle θ when the length of the arc-shaped portion 5e is the minimum required maxis expressed as follows using the angle θ2 formed by the chamfered portion 2a of the workpiece 2 with respect to the horizontal direction and the radius of curvature R2 of the curved portion: A2=R2-R2sinθ2+rtan(θ2-θ max )×cosθ2=R2(1-sinθ2)+rtan(θ2-θ max )×cosθ2 [A2-R2(1-sinθ2)] / rcosθ2=tan(θ2-θ max ) θ2-θ max =tan -1 {[A2-R2(1-sinθ2)] / rcosθ2} θ max = θ2 - tan -1 {[A2-R2(1-sin θ2)] / r cos θ2} By such calculation, it is possible to set the condition for the arc-shaped portion 5e to have a length equal to or greater than the length of the chamfered portion 2a on the lower surface side of the workpiece 2 having the desired cross-sectional shape. The angle θ for determining the lower limit of the length of the arc-shaped portion 5e is set based on the radius of curvature R2, angle θ2, and distance A2, which are the dimensions of the desired cross-sectional shape of the workpiece 2 shown in Figures 7A and 8. max is required.

[0062] The arc-shaped portion 5e of the grindstone is at an angle θ from the vertical direction calculated as above. max and angle θ4, the workpiece 2 can be accurately and satisfactorily machined into the desired cross-sectional shape. This relationship applies regardless of the magnitude relationship between angle θ2 and angle θ3. The above description is based on the dimensions of each part on the lower side of the workpiece 2 having the desired cross-sectional shape and the dimensions of each part of the arc-shaped portion 5e on the lower side of the grinding wheel 5 in a configuration in which the lower side of the workpiece 2 is attracted by the attracting member 10. Regarding a configuration in which the upper side of the workpiece 2 is attracted by the attracting member 10, the conditions for satisfactorily grinding the upper surface of the workpiece 2 with the grinding wheel 5 can be determined in a manner substantially similar to the calculation described above, based on the dimensions of each part on the upper side, not the lower side, of the workpiece 2 having the desired cross-sectional shape and the dimensions of each part of the arc-shaped portion 5e on the upper side, not the lower side, of the grinding wheel 5.

[0063] Next, a second embodiment of the present invention will be described. Figure 12 is a cross-sectional view showing the grinding wheel 5 of the workpiece processing apparatus 1 of this embodiment. Similar to the grinding wheel 5 of the first embodiment, the grinding wheel 5 of this embodiment includes a base disk portion 5a, a concave grinding portion 5b located on the outer periphery of the base disk portion 5a, and a grinding portion 5g having a rectangular cross section and aligned with the concave grinding portion 5b in the thickness direction. The base disk portion 5a and the grinding portion 5g have substantially the same configuration as the base disk portion 5a and the grinding portion 5g having a rectangular cross section of the first embodiment, and therefore their description will be omitted. The cross-sectional shape of the concave grinding portion 5b in a cross section taken along the rotation axis 6 of the grinding wheel 5 is concave, recessed from the radially outer side (outer periphery) to the radially inner side (inner periphery), and includes an arc-shaped portion 5e at each end in the thickness direction and a slope portion 5h located outside the arc-shaped portion 5e in the thickness direction and continuously connected to the arc-shaped portion 5e. Between the arc-shaped portions 5e at both ends is a straight portion 5f having a thickness equal to or greater than that of the workpiece 2. At point B, where the angle at which the tangent to the arc-shaped portion 5e is inclined relative to the horizontal direction coincides with the angle θ2 formed by the chamfered portion 2a of the workpiece 2 having the desired cross-sectional shape relative to the horizontal direction, the arc-shaped portion 5e transitions to a sloped portion 5h. Therefore, the sloped portion 5h extends at an angle θ2 relative to the horizontal direction.

[0064] In this embodiment, conditions are determined for abutting one side of the workpiece 2 (e.g., the vertical lower surface) against the grinding wheel 5 while the workpiece 2 is being attracted by the attraction member 10, thereby achieving satisfactory grinding. The length of the inclined portion 5h located on the side of the workpiece 2 that is attracted by the attraction member 10 (e.g., the vertical lower surface) is less than the length at which the inclined portion 5h abuts against the tapered shape 10a of the attraction member 10 when the tangent to the arc-shaped portion 5e extends at an angle θ3 that coincides with the angle θ3 of the tapered shape 10a of the attraction member 10 in a cross section along the rotation axis 6 of the grinding wheel 5 (point A in FIG. 13 ). In the state shown in FIG. 13 , the tangent to the arc-shaped portion 5e at point A is inclined by θ3 from the horizontal and is parallel to the lower surface of the tapered shape 10a of the attraction member 10. In this state, if the inclined portion 5h extends to point E where the lower surface of the tapered shape 10a of the suction member 10 abuts on the inclined portion 5h, further grinding is not possible. Therefore, the length of the inclined portion 5h is less than the length to point E. The angle that a line extending from the center of curvature of the arc-shaped portion 5e to point E makes with the vertical direction is defined as θ5. When a line is drawn that is parallel to the tangent at point A of the arc-shaped portion 5e, i.e., perpendicular to the radius that passes through point A and passes through point E, the distance from this line to point B along the radius that passes through point B is defined as x5. Furthermore, the distance along this line between the radius that passes through point A and the radius that passes through point B is defined as x4. x5 = r' - x4 tan [(θ3 - θ2) / 2] x4 = (r - r') tan (θ3 - θ2) x3 = r tan (θ2 - θ5) = x5 / tan (θ3 - θ2) θ5 = θ2 - tan -1 [x5 / r tan(θ3-θ2)] By such a calculation, it is possible to set the condition that the inclined surface portion 5h has a length less than the length at which the inclined surface portion 5h abuts against the tapered shape 10a of the attraction member 10, in a state where the concave grinding portion 5b abuts against the end portion on the lower surface side of the workpiece 2 at a position where the tangent of the arc-shaped portion 5e extends at an angle θ3 that coincides with the angle θ3 of the tapered shape 10a of the attraction member 10. Therefore, it is possible to set the condition that the inclined surface portion 5h of the grinding wheel 5 has a length less than the length at which the inclined surface portion 5h abuts against the tapered shape 10a of the attraction member 10, in a state where the concave grinding portion 5b abuts against the end portion on the lower surface side of the workpiece 2 at a position where the tangent of the arc-shaped portion 5e extends at an angle θ3 that coincides with the angle θ3 of the tapered shape 10a of the attraction member 10. max and the angle θ5, the workpiece 2 can be machined into a desired cross-sectional shape with good precision.

[0065] Next, a third embodiment of the present invention will be described. FIG. 14 is a front view schematically illustrating a workpiece machining apparatus according to this embodiment. The workpiece machining apparatus according to this embodiment includes a grinding wheel 5 similar to the grinding wheel 5 of the first embodiment, but having a rectangular cross-sectional grinding portion 5g only on its upper surface, and a circular grooved grinding wheel 12 disposed at an angle relative to the tangent direction of the outer periphery of the circular workpiece 2. The grooved grinding wheel 12 is supported by a grooved grinding wheel support mechanism 13 and is rotatable about a rotation axis 14. This workpiece machining apparatus performs chamfering through a two-stage grinding process. The first stage, a rough grinding process, is performed by implementing the above-described machining method using the rectangular cross-sectional grinding portion 5g and the concave grinding portion 5b of the grinding wheel 5, similar to that of the first embodiment. The second stage, a precision grinding process, is performed using the grooved grinding wheel 12 disposed at an angle relative to the tangent direction of the outer periphery of the workpiece 2. A concave groove 12a is provided on the outer periphery of the grooved grinding wheel 12, and by inserting the outer periphery of the workpiece 2 into this groove 12a, the inner periphery of the groove 12a is brought into contact with the outer periphery of the workpiece 2 to grind it, thereby forming a chamfer. According to this embodiment, the effects of the helical processing method, such as low surface roughness, can be obtained, and by performing rough grinding with the grinding wheel 5 that moves while rotating, there is also the effect that the subsequent helical precision grinding using the grooved grinding wheel 12 can be performed more efficiently in a shorter time.

[0066] The workpiece processing device of this embodiment has a truing grindstone 11 for truing the grooved grindstone 12, which can be attached to the workpiece support mechanism 4 instead of the workpiece 2 and is rotatable about the rotation axis 3. The truing grindstone 11 is made of, for example, a GC grindstone or the like which is harder than the grooved grindstone 12 made of a resin bond grindstone, and is a grindstone having a diameter and thickness approximately equal to those of the workpiece 2. The truing grindstone 11 made of a GC grindstone or the like is processed in the same manner as the workpiece 2, using a grindstone 5 which is usually made of a metal bond grindstone, to form a cross-sectional shape (a shape corresponding to the shape of the preset grooves 12a) that is to be transferred to the inclined grooved grindstone 12. The method similar to that for machining the workpiece 2 involves calculating, based on the radius of curvature of the arc-shaped portion 5e of the grinding wheel 5, movement conditions under which the contact portion between the concave grinding portion 5b of the grinding wheel 5 and the truing grinding wheel 11 moves along a shape corresponding to the predetermined shape of the groove 12a, and then moving the truing grinding wheel 11 relative to the grinding wheel 5 according to the movement conditions to form the outer shape of the truing grinding wheel 11. The predetermined shape of the groove 12a is a shape suitable for forming the workpiece 2 abutting the inner peripheral surface of the groove 12a into a desired cross-sectional shape. The truing grinding wheel 11 having the cross-sectional shape thus formed is rotated around the rotation axis 3 and pressed against the outer peripheral portion of the inclined grooved grinding wheel 12 before the groove is formed or shaped, thereby transferring the outer shape of the truing grinding wheel 11 to the outer peripheral portion of the grooved grinding wheel 12 and forming or shaping the groove 12a. In this way, truing of the grooved grinding wheel 12 can be easily performed. The truing grinding wheel 11 is formed in a shape that takes into account the slight changes in cross-sectional shape that occur during truing of the inclined grooved grinding wheel 12, based on empirical predictions.

[0067] In terms of the abrasion resistance of a grinding wheel, for example, a GC grinding wheel with a grit size of #320 is stronger than a resin-bonded grinding wheel with a grit size of #3000, and a metal-bonded grinding wheel with a grit size of #800 is stronger than a GC grinding wheel with a grit size of #320. Therefore, a GC grinding wheel with a grit size of #320 can be ground with a metal-bonded grinding wheel with a grit size of #800 to form a desired cross-sectional shape. Furthermore, the shape of the groove can be shaped by pressing a GC grinding wheel with a grit size of #320 against the inner surface of a groove in a resin-bonded grinding wheel with a grit size of #3000. The grinding wheels described below basically have the grit sizes described above. In a conventional workpiece processing device that performs rough grinding using a metal-bonded grinding wheel with a formed groove and precision grinding using a resin-bonded grinding wheel with an inclined groove, a truing wheel made of a GC grinding wheel is brought into contact with the inner surface of the formed groove of the metal-bonded grinding wheel to transfer the shape of the formed groove. The truing wheel made of a GC grinding wheel is then brought into contact with the inclined resin-bonded grinding wheel to form or shape the groove. Precision grinding of the workpiece (wafer) is performed using the groove of the inclined grooved grinding wheel made of a resin-bonded grinding wheel thus formed. Therefore, the workpiece can only be formed into a cross-sectional shape that depends on the shape of the formed groove of the metal-bonded grinding wheel, and cannot be formed into a different cross-sectional shape.

[0068] In contrast, in the present invention, the truing grinding wheel 11 made of a GC grinding wheel can be formed into any cross-sectional shape by the concave grinding portion 5b of the grinding wheel 5 made of a metal-bonded grinding wheel. Therefore, grooves 12a of any cross-sectional shape can be formed in the grooved grinding wheel 12 trued by this truing grinding wheel 11. This allows for machining of workpieces 2 with various cross-sectional shapes without the need to replace the grinding wheel. Furthermore, after truing the grooved grinding wheel 12, the workpiece 2 can be machined once, and the cross-sectional shape of the machined workpiece 2 can be actually measured and compared with the target shape for feedback. If the cross-sectional shape of the machined workpiece 2 differs from the target shape, the cross-sectional shape of the truing grinding wheel 11 shaped by the concave grinding portion 5b of the grinding wheel 5 can be changed (corrected), and the grooved grinding wheel 12 can be re-trued using the truing grinding wheel 11 having the changed cross-sectional shape. In this way, the cross-sectional shape of the workpiece 2 shaped by the grooved grinding wheel 12 can be made closer to the target shape. The conventional workpiece machining apparatus described above uses a metal bond grinding wheel having a formed groove, so even if the cross-sectional shape of the machined workpiece differs from the target shape, it is impossible to change (correct) the cross-sectional shape of the truing grinding wheel 11. However, according to the method of the present invention, it is possible to significantly improve the accuracy of the cross-sectional shape of the machined workpiece, i.e., the machining accuracy of the workpiece 2.

[0069] Next, a fourth embodiment of the present invention will be described. FIG. 15 is a front view schematically illustrating a workpiece machining apparatus according to this embodiment. Similar to the third embodiment, this workpiece machining apparatus includes a grooved grinding wheel 12 disposed obliquely relative to the tangent direction of the outer periphery of a disk-shaped workpiece 2. A grinding wheel 5 similar to that of the third embodiment is attached to a grinding wheel support mechanism 7 and is rotatable about a rotation axis 6. The workpiece 2 is attached to a workpiece support mechanism 4 and is rotatable about a rotation axis 3. The workpiece 2 is movable within a plane parallel to the workpiece 2 and grinding wheel 5 (i.e., within a plane perpendicular to the rotation axis 3 and the rotation axis 6) toward and away from the grinding wheel 5, and is also movable within a plane perpendicular to the grinding wheel 5 and workpiece 2 (i.e., within a plane parallel to the rotation axis 3 and the rotation axis 6) toward and away from the grinding wheel 5. As shown in FIG. 15, the workpiece support mechanism 4 includes an X-direction moving stage 4a, a Y-direction moving stage 4b, a Z-direction moving stage 4c, and a motor 4d. The X-direction moving stage 4a is movable in the width direction of the grinding wheel 5 and workpiece 2 (a direction perpendicular to the plane of the paper in FIG. 15 ) within a plane parallel to the grinding wheel 5 and workpiece 2. The Y-direction moving stage 4b ​​is mounted on the X-direction moving stage 4a and is movable in the direction of approaching and separating the grinding wheel 5 and workpiece 2 (left and right in FIG. 15 ) within a plane parallel to the grinding wheel 5 and workpiece 2. The Z-direction moving stage 4c is mounted on the Y-direction moving stage 4b ​​and is movable in the height direction (up and down in FIG. 15 ) within a plane perpendicular to the grinding wheel 5 and workpiece 2. Although not described in detail, the X-direction moving stage 4a, the Y-direction moving stage 4b, and the Z-direction moving stage 4c each have known guide means (e.g., LM guides) and movement means (e.g., ball screws, nuts, and rotational drive means) and are movable in the aforementioned directions. The motor 4d is mounted on the Z-direction moving stage 4c and supports the workpiece 2 via the rotational shaft 3 and is a drive means for rotating the rotational shaft 3. The motor 4d is a heat-generating member, and a temperature adjustment mechanism 15 is provided to cover at least one of the motor 4d and the rotating shaft 3. The temperature adjustment mechanism 15 adjusts the temperature of at least one of the motor 4d and the rotating shaft 3 by allowing a liquid or gas to flow through a flow path (not shown).

[0070] This workpiece machining device can achieve the effects of each of the first to third embodiments described above. In addition, although not shown, a truing grindstone 11 similar to that of the third embodiment can be moved so as to come into contact with the grooved grindstone 12 while rotating, thereby truing the grooved grindstone 12 easily, efficiently, and with high precision.

[0071] The workpiece support mechanism 4 does not always rotate the workpiece 2 at high speed; sometimes it rotates the workpiece 2 at low speed, or sometimes it does not rotate the workpiece 2 at all. Specifically, when grinding the workpiece 2 using the concave grinding portion 5b or the rectangular cross-section grinding portion 5g of the grinding wheel 5, the workpiece 2 is rotated at high speed. When grinding the workpiece 2 using a grooved grinding wheel 12 arranged obliquely with respect to the tangent direction of the outer periphery of the disk-shaped workpiece 2, the workpiece 2 is rotated at low speed. Furthermore, when replacing the workpiece 2, the workpiece support mechanism 4 does not need to rotate. Conventionally, when machining multiple workpieces 2 continuously, the workpiece support mechanism 4 alternates between high-speed rotation of the workpiece 2 around the rotation axis 3, low-speed rotation of the workpiece 2, and a stopped state of rotation. The workpiece support mechanism 4 generates heat and becomes high temperature when the workpiece 2 rotates at high speed, becomes lower when the workpiece 2 rotates at low speed, and becomes even lower when the rotation is stopped. Repeated temperature changes in the workpiece support mechanism 4 cause deformation, particularly expansion and contraction, of the rotation axis 3. If the rotating shaft 3 on which the workpiece 2 is attached is deformed and the position of the workpiece 2 in the thickness direction changes, the machining accuracy will be significantly reduced even if the workpiece 2 and the grinding wheel are moved relative to each other using numerical control as described above.

[0072] Therefore, in each embodiment of the present invention, a temperature adjustment mechanism 15 is provided that is attached to the workpiece support mechanism 4. The temperature adjustment mechanism 15 generates a flow of liquid or gas to reduce temperature fluctuations in the rotating shaft 3 of the workpiece support mechanism 4 and suppress deformation of the rotating shaft 3. In this way, by suppressing deformation of the rotating shaft 3 due to heat when machining the workpiece 2, a decrease in the machining accuracy of the workpiece 2 is prevented.

[0073] Furthermore, in order to keep the temperature of the rotating shaft 3 as constant as possible, it is preferable to continue the rotational motion about the rotating shaft 3. For example, it is preferable for the work support mechanism 4 to continue the rotational motion about the rotating shaft 3 even when the workpiece 2 is replaced or replenished or when machining of the workpiece 2 is interrupted due to a problem in the work process. In this way, by keeping the work support mechanism 4 in a state where it is rotating about the rotating shaft 3 while the workpiece 2 is not attached and machining of the workpiece 2 is not being performed (for convenience, referred to as an idling state or pre-rotation operation), temperature fluctuations can be kept small, making it easier for the temperature to stabilize in a short period of time. Furthermore, in this pre-rotation operation, instead of performing only high-speed rotation or only low-speed rotation, it is preferable to alternately rotate the workpiece 2 between high-speed rotation (at the same speed as when the workpiece 2 is rotating at high speed during machining with the grinding wheel) and low-speed rotation (at the same speed as when the workpiece 2 is rotating at low speed during machining with the grinding wheel), as in actual machining of the workpiece 2, in order to keep temperature fluctuations small. This allows the temperature of the rotating shaft 3 to be stabilized immediately when transitioning from the preliminary rotation operation to machining of the workpiece 2, enabling high-precision machining. In particular, it is preferable to match the ratio of the duration of high-speed rotation to the duration of low-speed rotation in the preliminary rotation operation with the ratio of the duration of high-speed rotation to the duration of low-speed rotation in the actual machining of the workpiece 2, since this allows temperature control similar to that during actual machining of the workpiece 2. However, if the durations of high-speed rotation and low-speed rotation in the preliminary rotation operation are long, when starting actual machining of the workpiece 2, the waiting time required to wait for the appropriate timing to end the preliminary rotation operation and transition to machining of the workpiece 2 (for example, the timing at which the rotation speed of the preliminary rotation operation is switched) becomes long, which may reduce work efficiency. Therefore, as mentioned above, it is preferable to match the ratio between the duration of high-speed rotation and the duration of low-speed rotation in the preparatory rotation operation with the ratio between the duration of high-speed rotation and the duration of low-speed rotation in the actual processing of the workpiece 2, while making the duration of high-speed rotation and the duration of low-speed rotation in the preparatory rotation operation shorter than the duration of high-speed rotation and the duration of low-speed rotation in the actual processing of the workpiece 2, respectively.This allows temperature control similar to that used when actually machining the workpiece 2 to minimize temperature changes in the rotating shaft 3 and prevent a decrease in machining accuracy, and further shortens the waiting time when transitioning from the preliminary rotation operation to machining the workpiece 2, thereby preventing a decrease in work efficiency.

[0074] In the grinding wheel 5 of the present invention, the cross-sectional shape of the concave grinding portion 5b in a cross section passing through the rotation axis 6 of the grinding wheel 5 has a cross-sectional shape in which a pair of arc-shaped portions 5e located at both ends in the thickness direction are connected by a straight portion 5f. The arc-shaped portion 5e at one end in the thickness direction of the grinding wheel 5 and the arc-shaped portion 5e at the other end are preferably individually formed so that the average value of the respective radii of curvature is a desired size. This allows both ends in the thickness direction to be formed with higher precision and better results than when the entire concave grinding portion 5b is machined to have the same radius of curvature. It is also preferable to reduce the error in the radius of curvature of the arc-shaped portion 5e at one end in the thickness direction and the arc-shaped portion 5e at the other end to a certain extent. For example, the difference between the maximum and minimum values ​​of the radii of curvature of the arc-shaped portion 5e at one end in the thickness direction and the difference between the maximum and minimum values ​​of the radii of curvature of the arc-shaped portion 5e at the other end are both within an allowable range, i.e., not more than a predetermined value (first predetermined value).Furthermore, the difference between the average value of the radii of curvature of the arc-shaped portion 5e at one end in the thickness direction and the average value of the radii of curvature of the arc-shaped portion 5e at the other end is both within an allowable range, i.e., not more than a predetermined value (second predetermined value).

[0075] As described above, in the present invention, a disk-shaped workpiece 2 is formed into a desired cross-sectional shape using a grinding wheel 5 having a concave grinding portion 5b on its outer periphery, the concave grinding portion 5b having arc-shaped portions 5e at both ends in the thickness direction and a straight portion 5f between the arc-shaped portions 5e at both ends. This workpiece machining method includes the steps of: arranging the workpiece 2 and the grinding wheel 5 parallel to each other; and, while rotating the grinding wheel 5 and rotating the workpiece 2 about a rotation axis 3 parallel to the rotation axis 6 of the grinding wheel 5, moving the grinding wheel 5 relative to the workpiece 2 in accordance with movement conditions calculated based on the radius of curvature of the arc-shaped portions 5e of the grinding wheel 5 so that the contact portion between the concave grinding portion 5b and the workpiece 2 moves along the desired cross-sectional shape of the workpiece 2. The step of moving the grinding wheel 5 relative to the workpiece 2 includes: rotating the workpiece 2 and the grinding wheel 5, while moving the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5 in a curved manner relative to the workpiece 2 from the outer peripheral end face of the workpiece 2 toward one side by an angle calculated in advance in accordance with the movement conditions, thereby grinding the outer periphery of one side of the workpiece 2; moving the grinding wheel 5 along the outer peripheral end face of the workpiece 2 from one side to the other side relative to the workpiece 2; and rotating the workpiece 2 and the grinding wheel 5, while moving the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5 in a curved manner relative to the workpiece 2 from the outer peripheral end face of the workpiece 2 toward the other side by an angle calculated in advance in accordance with the movement conditions, thereby grinding the outer periphery of the other side of the workpiece 2. When roughly grinding the outer periphery of one side or the other side of the workpiece 2, while rotating the workpiece 2 and the grinding wheel 5, the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5 is moved in a curved line relative to the workpiece 2 by an angle calculated in advance in accordance with the movement conditions from the outer peripheral end face of the workpiece 2 toward one side or the other side so that the rotation axis 6 of the grinding wheel 5 and the rotation axis 3 of the workpiece 2 are positioned in the same plane (along arrow F1 in Figure 16), and then the relative movement of the grinding wheel 5 relative to the workpiece 2 is stopped.On the other hand, when performing precise grinding of the outer periphery of one side or the other side of the workpiece 2, while rotating the workpiece 2 and the grinding wheel 5, the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5 is moved in a curved line relative to the workpiece 2 from the outer peripheral end surface of the workpiece 2 toward one side or the other side (along arrow F1 in Figure 16) so that the rotation axis 6 of the grinding wheel 5 and the rotation axis 3 of the workpiece 2 are positioned in the same plane, and then the grinding wheel 5 is moved linearly relative to the workpiece 2 (for example, along any of arrows F2, F3, F4, or F5 in Figure 16) so that the rotation axis 6 of the grinding wheel 5 and the rotation axis 3 of the workpiece 2 move relative to each other in a plane extending perpendicularly or obliquely to the plane in which the rotation axis 6 of the grinding wheel 5 and the rotation axis 3 of the workpiece 2 were positioned during the curved movement.

[0076] According to this method, the ground portion of the workpiece 2 is improved in roughness (becomes smoother). The reason for this is that the surface of the grinding wheel 5 (the surface used for grinding) is dotted with portions where abrasive grains such as diamonds protrude. At the contact portion of the workpiece 2 with the grinding wheel 5, the portions where the abrasive grains such as diamonds of the grinding wheel 5 protrude are cut deeper than other portions. By subsequently moving the grinding wheel 5 linearly relative to the workpiece 2, the entire area of ​​the workpiece 2, including the deeply cut portions, is re-ground by the arc-shaped portions 5e of the concave grinding portion 5b of the grinding wheel 5. As a result, the deeply cut portions that were cut deeply by contact with the abrasive grains such as diamonds in the previous process are not left as they are, but are ground smooth by contacting the arc-shaped portions 5e of the concave grinding portion 5b of the grinding wheel 5. In particular, by changing the relative movement direction between the rotation axis 6 of the grinding wheel 5 and the rotation axis 3 of the workpiece in the previous process, and by moving the grinding wheel 5 relative to the workpiece 2 in a direction that intersects perpendicularly or obliquely with the relative movement direction between the grinding wheel 5 and the workpiece 2 during curved movement, and in a direction that is oblique or perpendicular to the rotation direction of the workpiece 2, it is possible to re-grind areas that include parts that have been deeply engraved by contact with abrasive grains such as diamonds in the previous process, and it is also possible to prevent the workpiece 2 from being excessively ground by the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5, resulting in an angle that becomes too small.

[0077] In addition, in the present invention, a disk-shaped workpiece 2 may be formed into a desired cross-sectional shape using a grinding wheel 5 having a concave grinding portion 5b on its outer periphery, the concave grinding portion 5b having, at both ends in the thickness direction, an arc-shaped portion 5e and a slope portion 5h located outside the arc-shaped portion 5e in the thickness direction and continuously connected to the arc-shaped portion 5e, and a straight portion 5f between the arc-shaped portions 5e at both ends. This workpiece machining method includes the steps of: disposing the workpiece 2 and the grinding wheel 5 parallel to each other; and rotating the grinding wheel 5 and rotating the workpiece 2 about a rotation axis 3 parallel to the rotation axis 6 of the grinding wheel 5, while moving the grinding wheel 5 relative to the workpiece 2 in accordance with movement conditions calculated based on the radius of curvature of the arc-shaped portion 5e of the grinding wheel 5 so that the contact portion between the concave grinding portion 5b and the workpiece 2 moves along the desired cross-sectional shape of the workpiece 2. The step of moving the grinding wheel 5 relative to the workpiece 2 includes: rotating the workpiece 2 and the grinding wheel 5, while moving the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5 in a curved manner relative to the workpiece 2 from the outer peripheral end face of the workpiece 2 toward one side by an angle calculated in advance in accordance with the movement conditions, thereby grinding the outer periphery of one side of the workpiece 2; moving the grinding wheel 5 along the outer peripheral end face of the workpiece 2 from one side to the other side relative to the workpiece 2; and rotating the workpiece 2 and the grinding wheel 5, while moving the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5 in a curved manner relative to the workpiece 2 from the outer peripheral end face of the workpiece 2 toward the other side by an angle calculated in advance in accordance with the movement conditions, thereby grinding the outer periphery of the other side of the workpiece 2. When roughly grinding the outer periphery of one side or the other side of the workpiece 2, while rotating the workpiece 2 and the grinding wheel 5, the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5 is moved in a curved line relative to the workpiece 2 by an angle calculated in advance in accordance with the movement conditions from the outer peripheral end face of the workpiece 2 toward one side or the other side so that the rotation axis 6 of the grinding wheel 5 and the rotation axis 3 of the workpiece 2 are positioned in the same plane (along arrow F1 in Figure 16), and then the relative movement of the grinding wheel 5 relative to the workpiece 2 is stopped.On the other hand, when performing precise grinding of the outer periphery of one side or the other side of the workpiece 2, while rotating the workpiece 2 and the grinding wheel 5, the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5 is moved in a curved line relative to the workpiece 2 from the outer peripheral end face of the workpiece 2 toward one side or the other side (along the arrow F1 in Figure 16) so that the rotation axis 6 of the grinding wheel 5 and the rotation axis 3 of the workpiece 2 are positioned in the same plane, and then the grinding wheel 5 is moved linearly relative to the workpiece 2 (continuing to move along the arrow F1 in Figure 16) while maintaining the state in which the rotation axis 6 of the grinding wheel 5 and the rotation axis 3 of the workpiece 2 are positioned in the plane in which they were positioned during the curved movement.

[0078] According to this method, the concave grinding portion 5b of the grinding wheel 5 has a sloped surface 5h, so that the area including the deeply engraved portion due to contact with abrasive grains such as diamond is ground again by the sloped surface 5h of the grinding wheel 5. This smooths out the deeply engraved portion due to contact with abrasive grains such as diamond in the previous process, without leaving it as it is. Furthermore, because the workpiece 2 is ground by the sloped surface 5h last, there is no risk of excessive grinding that reduces the angle. Therefore, there is no need to change the direction of movement between the grinding wheel 5 and the workpiece 2 during the curved relative movement and the subsequent linear relative movement, and the workpiece 2 can be pulled out in a straight line when viewed from above.

[0079] Furthermore, in the present invention, a workpiece processing method for forming a disk-shaped workpiece 2 into a desired cross-sectional shape using a grinding wheel 5 having a concave grinding portion 5b on its outer periphery, wherein the concave grinding portion 5b has a shape having arc-shaped portions 5e at both ends in the thickness direction and a straight portion 5f between the arc-shaped portions 5e at both ends, includes the steps of arranging the workpiece 2 and the grinding wheel 5 parallel to each other, and rotating the grinding wheel 5 and rotating the workpiece 2 around a rotation axis 3 parallel to the rotation axis 6 of the grinding wheel 5, while moving the grinding wheel 5 relative to the workpiece 2 in accordance with movement conditions calculated based on the radius of curvature of the arc-shaped portion 5e of the grinding wheel 5 so that the contact portion between the concave grinding portion 5b and the workpiece 2 moves along the desired cross-sectional shape of the workpiece 2. The step of moving the grinding wheel 5 relative to the workpiece 2 includes: rotating the workpiece 2 and the grinding wheel 5, while moving the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5 in a curved manner relative to the workpiece 2 from the outer peripheral end face of the workpiece 2 toward one side by an angle calculated in advance in accordance with the movement conditions, thereby grinding the outer periphery of one side of the workpiece 2; moving the grinding wheel 5 along the outer peripheral end face of the workpiece 2 from one side to the other side relative to the workpiece 2; and rotating the workpiece 2 and the grinding wheel 5, while moving the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5 in a curved manner relative to the workpiece 2 from the outer peripheral end face of the workpiece 2 toward the other side by an angle calculated in advance in accordance with the movement conditions, thereby grinding the outer periphery of the other side of the workpiece 2. When roughly grinding the outer periphery of one surface side or the other surface side of the workpiece 2, the workpiece 2 and the grinding wheel 5 are rotated, and the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5 is moved in a curved line relative to the workpiece 2 by an angle calculated in advance in accordance with the movement conditions from the outer peripheral end face of the workpiece 2 toward one surface or the other surface, and then the movement of the grinding wheel 5 relative to the workpiece 2 is stopped. When precisely grinding the outer periphery of one surface side of the workpiece 2, the workpiece 2 is rotated, and the outermost position (for example, H in FIG. 18 ) on one surface side in the thickness direction through which the workpiece 2 passes during rotation is determined, taking into account a positional error in the thickness direction that occurs during rotation of the workpiece 2. max), the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5 is moved in a curved line relative to the workpiece 2 from the outer peripheral end face of the workpiece 2 toward one side by an angle calculated in advance in accordance with the movement conditions, and then the movement is stopped, and at a position where the grinding wheel 5 contacts the slope of the chamfered portion 2a on one side of the workpiece 2, the rotation speed of the workpiece 2 is slowed down and rotated at least one revolution while adjusting the position in the thickness direction of the workpiece 2, thereby grinding one side of the workpiece 2 while canceling out positional errors during rotation of the workpiece 2. When performing precise grinding of the outer periphery on the other side of the workpiece 2, while rotating the workpiece 2 and the grinding wheel 5, the outermost position (for example, H in FIG. 18 ) on the other side of the thickness direction through which the workpiece 2 passes during rotation is determined taking into account positional errors in the thickness direction that occur during rotation of the workpiece 2. min ), the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5 is moved in a curved line relative to the workpiece 2 from the outer peripheral end surface of the workpiece 2 toward the other surface by an angle calculated in advance in accordance with the movement conditions, and then the movement is stopped.At a position where the grinding wheel 5 contacts the slope of the chamfered portion 2a on the other surface of the workpiece 2, the rotation speed of the workpiece 2 is slowed down and the workpiece 2 is rotated at least one revolution while adjusting the position in the thickness direction of the workpiece 2, thereby grinding the other surface of the workpiece 2 while canceling out any positional error that may occur during the rotation of the workpiece 2.

[0080] To explain the technical significance of this method, when the workpiece 2 and grinding wheel 5 are rotated as in the above-described embodiments, there is a possibility that the position of the workpiece 2 may deviate in the direction parallel to the rotation axis (thickness direction) during rotation. Generally, an error of approximately ±1.5 μm to ±3 μm occurs in the thickness direction position. Such thickness direction error also significantly varies the planar shape of the workpiece 2 after grinding. In particular, when the angles θ1 and θ2 of the workpiece 2 shown in FIGS. 7A and 8 are small, the thickness direction positional deviation results in a large horizontal (in-plane) positional deviation. Specifically, as schematically shown in FIG. 7B , if we imagine a right triangle with the upper thickness direction positional deviation O1 as the opposite side and the horizontal direction positional deviation K1 as the base, then tan θ1 = O1 / K1, i.e., K1 = O1 / tan θ1. Similarly, as shown schematically in FIG. 7C, if we imagine a right-angled triangle with the thickness-direction misalignment O2 on the lower side as the opposite side and the horizontal-direction misalignment K2 as the base, then tan θ2 = O2 / K2, i.e., K2 = O2 / tan θ2. For example, when the angles θ1 and θ2 are 22°, the horizontal misalignments K1 and K2 are approximately 2.5 times the thickness-direction misalignments O1 and O2. Therefore, when the thickness-direction misalignments O1 and O2 are ±3 μm, the horizontal misalignments K1 and K2 are approximately ±7.5 μm. The R-shaped workpiece 2 shown in FIG. 8 also exhibits the same relationship between the horizontal misalignments K1 and K2 and the thickness-direction misalignments O1 and O2 as the T-shaped workpiece 2 shown in FIG. 7A (see FIGS. 7B-7C). As mentioned above, there is a possibility of an error of up to 7.5 μm in the dimensions of the top and bottom surfaces of the workpiece 2 (e.g., dimensions A1 and A2 shown in FIGS. 7A and 7B). If the angles θ1 and θ2 are smaller, the error in the dimensions of the top and bottom surfaces of the workpiece 2 (for example, dimensions A1 and A2) will become even larger. Therefore, it is conceivable to investigate the tendency of the positional deviation in the thickness direction of the workpiece 2 while it is rotating, and to incorporate a piezoelectric element (not shown) or the like into the workpiece support mechanism 4, and to operate the piezoelectric element finely and at high speed while the workpiece 2 is rotating, thereby moving the workpiece 2 in the thickness direction so as to cancel out the positional deviation in the thickness direction. However, in this case, the structure of the workpiece support mechanism 4 would become very complicated, which would increase costs and make it more susceptible to malfunction.If the workpiece 2 is moved up and down at high speed in accordance with the high-speed rotation of the workpiece 2, the shape of the workpiece 2 after grinding will not be smooth, and the accuracy of the workpiece dimensions (for example, the radii of curvature R1 and R2 shown in Figures 7A and 8) may deteriorate. If we try to solve these problems by slowing down the rotation speed of the workpiece 2, the work efficiency will decrease and the processing costs will increase.

[0081] Therefore, in order not to reduce the work efficiency too much, it is preferable to operate the device for moving the workpiece 2 up and down and the accompanying movement of the workpiece 2 in the thickness direction only when necessary, rather than constantly while the workpiece 2 is rotating. Specifically, before precision grinding of the outer periphery of one surface side (upper surface side) and the other surface side (lower surface side) of the workpiece 2, the state of positional deviation in the thickness direction when the workpiece 2 is rotated by the work support mechanism 4 is checked. That is, while actually rotating the workpiece 2 by the work support mechanism 4, for example, the variation in the height direction of eight points H1 to H8 shown in FIG. 17 is measured. Then, among the heights of each of the points H1 to H8, the positive value H that has the largest difference from the midpoint of those heights is selected. max (For example, about +3 μm) and the largest negative value H min (For example, about -3 μm) Then, while rotating the workpiece 2 and the grinding wheel 5, the highest point H max With this as the reference, the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5 is moved in a curved line relative to the workpiece 2 from the outer peripheral end surface of the workpiece 2 toward the upper surface by an angle calculated in advance in accordance with the movement conditions, and then the movement is stopped. Then, at the position where the grinding wheel 5 contacts the slope of the chamfered portion 2a on the upper surface side of the workpiece 2, the rotation speed of the workpiece 2 is slowed down and the workpiece 2 is rotated at least one revolution while adjusting the position in the thickness direction of the workpiece 2, thereby grinding the upper surface side of the workpiece 2 while canceling out positional errors during rotation of the workpiece 2. Similarly, while rotating the workpiece 2 and the grinding wheel 5, the lowest point H in the thickness direction is adjusted. minUsing this as a reference, the arc-shaped portion 5e of the concave grinding portion 5b of the grinding wheel 5 is moved in a curved line relative to the workpiece 2 from the outer peripheral end face toward the underside of the workpiece 2 by an angle calculated in advance in accordance with the movement conditions, and then the movement is stopped. Then, at a position where the grinding wheel 5 contacts the slope of the chamfered portion 2a on the underside of the workpiece 2, the rotation speed of the workpiece 2 is slowed down while adjusting the position in the thickness direction of the workpiece 2, and the workpiece 2 is rotated at least one full rotation, thereby grinding the underside of the workpiece 2 while canceling out any positional errors that may occur during rotation of the workpiece 2.

[0082] According to this method, in the final stage of the grinding process, the workpiece 2 is ground while being moved in the thickness direction to cancel out positional errors during rotation of the workpiece 2. This results in a smooth ground surface and allows for the desired cross-sectional shape to be accurately formed. Furthermore, this thickness-wise movement and low-speed rotation of the workpiece 2 need only be performed for one or several rotations in the final stage of the grinding process; in the previous stages, the workpiece 2 is ground while being rotated at high speed without being moved in the thickness direction. This prevents large displacements in the horizontal (in-plane) dimension, which is the most important dimension for cross-sectional shape, caused by slight positional displacement in the thickness direction. The effects of the concave grinding wheel and the obtuse angled connection virtually eliminate the influence of the cross-sectional R and the junction of the sloped surface, enabling high-precision machining without significant reduction in work efficiency and reducing equipment failure. Because the thickness-wise movement of the workpiece 2 is performed while the workpiece 2 is rotating at a low speed, expensive devices such as piezoelectric elements are not required, and this method can be performed using a ball screw or the like. As such, this method achieves high machining precision for the workpiece 2, good work efficiency, and minimal machining costs. This method can also be implemented in combination with the above-mentioned method in which grinding is performed while the grinding wheel 5 and the workpiece 2 are moved relative to each other in a curved line and then moved relative to each other in a straight line.

[0083] [Supplementary Note 1] A workpiece processing device for forming a disc-shaped workpiece into a desired cross-sectional shape, comprising: a workpiece support mechanism for supporting the workpiece; a disc-shaped grinding wheel arranged parallel to the workpiece; and a grinding wheel support mechanism for supporting the grinding wheel, wherein the workpiece support mechanism rotates the workpiece, the grinding wheel support mechanism rotates the grinding wheel, and a rotation axis around which the workpiece is rotated by the workpiece support mechanism and a rotation axis around which the grinding wheel is rotated by the grinding wheel support mechanism are parallel to each other, the workpiece support mechanism has an adsorption member for adsorbing only one surface of the workpiece, the planar shape of the adsorption member is a circle with a radius smaller than the radius of the workpiece, and the outer periphery of the circular adsorption member has a tapered shape that becomes thinner as it goes outward, the grinding wheel has a concave grinding portion on its outer periphery, and the cross-sectional shape of the concave grinding portion in a cross section along the rotation axis of the grinding wheel is concave, recessed from the outer periphery toward the inner periphery, and has arc-shaped portions at least at both ends in the thickness direction, and has a straight portion having a thickness equal to or greater than the thickness of the workpiece between the arc-shaped portions at both ends; the grinding wheel and the workpiece can be moved relatively toward or away from each other by the grinding wheel support mechanism or the workpiece support mechanism; the grinding wheel support mechanism or the workpiece support mechanism moves the grinding wheel relatively to the workpiece in accordance with movement conditions calculated based on the radius of curvature of the arc-shaped portion of the grinding wheel so that the contact portion between the concave grinding portion and the workpiece moves along the desired cross-sectional shape of the workpiece; the radius of curvature of the arc-shaped portion of the grinding wheel is at least 10 times the thickness of the workpiece so that the arc-shaped portion of the grinding wheel abuts against the workpiece without generating a substantial gap between it and the chamfered portion of the desired cross-sectional shape of the workpiece;a workpiece machining device characterized in that the arc-shaped portion located on the one surface of the workpiece that is attracted by the suction member has a length that is less than the length that abuts the tapered shape of the suction member when in contact with the end of the one surface of the workpiece at a position where a tangent to the arc-shaped portion extends at an angle that matches the angle of the tapered shape of the suction member in a cross section along the rotation axis of the grinding wheel, and has a length that is greater than or equal to the length of the chamfered portion on the one surface of the workpiece having the desired cross-sectional shape.

[0084] [Appendix 2] A workpiece processing device for forming a disc-shaped workpiece into a desired cross-sectional shape, comprising: a workpiece support mechanism for supporting the workpiece; a disc-shaped grinding wheel arranged parallel to the workpiece; and a grinding wheel support mechanism for supporting the grinding wheel, wherein the workpiece support mechanism rotates the workpiece, the grinding wheel support mechanism rotates the grinding wheel, and a rotation axis around which the workpiece is rotated by the workpiece support mechanism and a rotation axis around which the grinding wheel is rotated by the grinding wheel support mechanism are parallel to each other, the workpiece support mechanism has an adsorption member for adsorbing only one surface of the workpiece, the planar shape of the adsorption member is a circle with a radius smaller than the radius of the workpiece, and the outer periphery of the circular adsorption member has a tapered shape that becomes thinner as it goes outward, the grinding wheel has a concave grinding portion on its outer periphery, and the cross-sectional shape of the concave grinding portion in a cross section along the rotation axis of the grinding wheel is concave, recessed from the outer periphery toward the inner periphery, and has an arc-shaped portion at least at both ends in the thickness direction, and a slope portion located outside the arc-shaped portion in the thickness direction and continuously connected to the arc-shaped portion, and has a straight portion having a thickness equal to or greater than the thickness of the workpiece between the arc-shaped portions at both ends; the grinding wheel and the workpiece can be moved relatively toward or away from each other by the grinding wheel support mechanism or the workpiece support mechanism; the grinding wheel support mechanism or the workpiece support mechanism moves the grinding wheel relative to the workpiece in accordance with movement conditions calculated based on the radius of curvature of the arc-shaped portion of the grinding wheel so that the contact portion between the concave grinding portion and the workpiece moves along the desired cross-sectional shape of the workpiece; and the radius of curvature of the arc-shaped portion of the grinding wheel is at least 10 times the thickness of the workpiece.a workpiece machining device characterized in that the inclined portion located on the one surface of the workpiece that is attracted by the suction member has a length that is less than the length at which the inclined portion abuts the tapered shape of the suction member when it is in contact with the end of the one surface of the workpiece at a position where, in a cross section along the rotation axis of the grinding wheel, a tangent to the arc-shaped portion extends at an angle that matches the angle of the tapered shape of the suction member, and has a length that is greater than or equal to the length of the chamfered portion on the one surface of the workpiece having the desired cross-sectional shape.

[0085] [Appendix 3] The workpiece processing device according to appendix 1 or 2, wherein the concave grinding portion and a grinding portion having a rectangular cross section, the surface facing the workpiece being a straight line parallel to the thickness direction of the grinding wheel in a cross section along the rotation axis, are provided side by side in the thickness direction on the outer periphery of the grinding wheel, and the rectangular cross section grinding portion of the grinding wheel abuts against the outer periphery of the workpiece before grinding by the concave grinding portion, and grinds the workpiece so as to reduce the radius of the workpiece by moving the grinding wheel from the outside to the inside in the radial direction of the workpiece.

[0086] [Supplementary Note 4] The workpiece machining device according to any one of Supplementary Notes 1 to 3, wherein a radius r1 of the suction member is expressed as r2-10t≦r1≦r2-5t when expressed in terms of a radius r2 of the desired cross-sectional shape of the workpiece and a thickness t of the workpiece, and an angle θ1 of the tapered shape of the suction member is expressed as θ2-10≦θ1≦θ2+5 when expressed in terms of an angle θ2 of the chamfered portion of the desired cross-sectional shape of the workpiece.

[0087] [Appendix 5] The workpiece processing device according to any one of Appendices 1 to 4, wherein the grinding wheel support mechanism has a spindle to which the grinding wheel is directly or indirectly attached, and a rotary bearing part that rotatably supports the spindle, and supports the grinding wheel so that the center of gravity of the grinding wheel is located between the attachment position of the grinding wheel and the rotary bearing part.

[0088] [Appendix 6] When grinding the outer periphery of one surface side of the workpiece, the grinding wheel support mechanism and the workpiece support mechanism rotate the workpiece and the grinding wheel, while moving the arc-shaped portion of the concave grinding portion of the grinding wheel in a curved line relative to the workpiece from the outer periphery end face of the workpiece toward one surface by an angle calculated in advance in accordance with the movement conditions, and when grinding the outer periphery of the other surface side of the workpiece, while rotating the workpiece and the grinding wheel, while moving the arc-shaped portion of the concave grinding portion of the grinding wheel in a curved line relative to the workpiece from the outer periphery end face of the workpiece toward the other surface by an angle calculated in advance in accordance with the movement conditions, The workpiece processing device described in any of Appendixes 1 to 5, wherein, when performing rough grinding of the outer periphery of the one surface side or the other surface side of the workpiece, the grinding wheel support mechanism and the workpiece support mechanism rotate the workpiece and the grinding wheel, while moving the arc-shaped portion of the concave grinding portion of the grinding wheel in a curved manner relative to the workpiece from the outer peripheral end face of the workpiece toward the one surface or the other surface by an angle calculated in advance in accordance with the movement conditions, and then stop the movement of the grinding wheel relative to the workpiece; and when performing precise grinding of the outer periphery of the one surface side or the other surface side of the workpiece, the grinding wheel support mechanism and the workpiece support mechanism rotate the workpiece and the grinding wheel, while moving the arc-shaped portion of the concave grinding portion of the grinding wheel in a curved manner relative to the workpiece from the outer peripheral end face of the workpiece toward the one surface or the other surface by an angle calculated in advance in accordance with the movement conditions, and then move the grinding wheel linearly relative to the workpiece.

[0089] [Appendix 7] A workpiece processing device as described in any of Appendices 1 to 6, further comprising, in addition to the grinding stone having the concave grinding portion, a disk-shaped grooved grinding stone arranged obliquely with respect to the tangential direction of the outer periphery of the workpiece and used for more precise grinding than grinding by the concave grinding portion of the grinding stone, and a grooved grinding stone support mechanism for supporting the grooved grinding stone, wherein the grooved grinding stone support mechanism rotates the grooved grinding stone.

[0090] [Appendix 8] The workpiece processing device according to Appendix 7, further comprising a truing wheel that can be attached to the workpiece support mechanism in place of the workpiece, wherein the truing wheel has an outer shape formed by being moved relative to the grinding wheel by the grinding wheel support mechanism or the workpiece support mechanism in accordance with the movement conditions, and the grooved grinding wheel has a groove formed or shaped by being pressed against the truing wheel and the outer shape of the truing wheel being transferred to the grooved grinding wheel.

[0091] [Appendix 9] The workpiece processing device according to any one of Appendices 1 to 8, wherein the workpiece support mechanism has a temperature adjustment mechanism that generates a flow of liquid or gas to keep the temperature of the rotation shaft of the workpiece support mechanism constant.

[0092] [Appendix 10] The grinding wheel included in the workpiece processing device described in appendix 1 or 2, characterized in that the straight portion has a grinding wheel grain size coarser than the arc-shaped portion, and the arc-shaped portion is used for more precise grinding than grinding by the straight portion.

[0093] [Appendix 11] The grinding wheel included in the workpiece processing device described in Appendix 3, characterized in that the grinding portion having a rectangular cross section is a portion having a coarser grinding grain size than the concave grinding portion, and the concave grinding portion is a portion used for more precise grinding than grinding by the grinding portion having a rectangular cross section.

[0094] [Appendix 12] The grinding wheel included in the workpiece processing device described in any one of Appendices 1 to 9, characterized in that the arc-shaped portion at one end in the thickness direction and the arc-shaped portion at the other end are individually formed portions so that the average value of each radius of curvature is a desired size.

[0095] [Appendix 13] The grinding wheel is included in the workpiece processing device described in any one of Appendices 1 to 9, characterized in that the difference between the maximum and minimum values ​​of the radius of curvature of the arc-shaped portion at one end in the thickness direction and the difference between the maximum and minimum values ​​of the radius of curvature of the arc-shaped portion at the other end are both equal to or less than a first predetermined value, and the difference between the average value of the radius of curvature of the arc-shaped portion at one end in the thickness direction and the average value of the radius of curvature of the arc-shaped portion at the other end is equal to or less than a second predetermined value.

[0096] [Supplementary Note 14] The grinding wheel included in the workpiece processing device according to any one of Supplementary Notes 1 to 9, characterized in that the grinding wheel has a straight or tapered mounting hole extending in the thickness direction.

[0097] [Appendix 15] A workpiece machining method for forming a disc-shaped workpiece into a desired cross-sectional shape using a rotatable, disc-shaped grinding wheel having a concave grinding portion on its outer periphery, the cross-sectional shape of the concave grinding portion in a cross section along the rotation axis of the grinding wheel being concave recessed from the outer periphery toward the inner periphery, the concave grinding portion having arc-shaped portions at least at both ends in the thickness direction, and a straight portion having a thickness equal to or greater than the thickness of the workpiece between the arc-shaped portions at both ends, the method comprising the steps of: disposing the workpiece and the grinding wheel parallel to each other; and rotating the grinding wheel and rotating the workpiece about an axis of rotation parallel to the axis of rotation of the grinding wheel, while moving the grinding wheel relatively to the workpiece in accordance with movement conditions calculated based on a radius of curvature of the arc-shaped portion of the grinding wheel so that a contact portion between the concave grinding portion and the workpiece moves along the desired cross-sectional shape of the workpiece, the step of moving the grinding wheel relatively to the workpiece comprising: the outer periphery of the one surface side of the workpiece by moving the arc-shaped portion of the concave grinding portion of the grinding wheel in a curved line relative to the workpiece from the outer periphery end face of the workpiece toward one surface by an angle calculated in advance in accordance with the movement conditions while rotating the workpiece and the grinding wheel; moving the grinding wheel along the outer periphery end face of the workpiece from the one surface side to the other surface side relative to the workpiece; and the outer periphery of the other surface side of the workpiece by moving the arc-shaped portion of the concave grinding portion of the grinding wheel in a curved line relative to the workpiece from the outer periphery end face of the workpiece toward the other surface by an angle calculated in advance in accordance with the movement conditions while rotating the workpiece and the grinding wheel.When performing rough grinding of the outer periphery of the one surface side or the other surface side of the workpiece, while rotating the workpiece and the grinding wheel, the arc-shaped portion of the concave grinding portion of the grinding wheel is moved in a curved line relative to the workpiece from the outer periphery end surface of the workpiece toward the one surface or the other surface by an angle calculated in advance in accordance with the movement conditions so that the rotation axis of the grinding wheel and the rotation axis of the workpiece are positioned in the same plane, and then the movement of the grinding wheel relative to the workpiece is stopped; A workpiece processing method characterized in that, when performing precision grinding of the outer periphery of the one surface side or the other surface side of the workpiece, while rotating the workpiece and the grinding wheel, the arc-shaped portion of the concave grinding portion of the grinding wheel is moved in a curved manner relative to the workpiece from the outer peripheral end face of the workpiece toward the one surface or the other surface by an angle calculated in advance in accordance with the movement conditions so that the rotation axis of the grinding wheel and the rotation axis of the workpiece are positioned in the same plane, and then the grinding wheel is moved linearly relative to the workpiece so that the rotation axis of the grinding wheel and the rotation axis of the workpiece move relative to each other in a plane extending in a direction perpendicular to or obliquely intersecting the plane in which the rotation axis of the grinding wheel and the rotation axis of the workpiece were positioned during the curved movement.

[0098] [Appendix 16] A workpiece machining method for forming a disc-shaped workpiece into a desired cross-sectional shape using a rotatable, disc-shaped grinding wheel having a concave grinding portion on its outer periphery, wherein the cross-sectional shape of the concave grinding portion in a cross section along the rotation axis of the grinding wheel is concave, recessed from the outer periphery toward the inner periphery, and has arc-shaped portions at least at both ends in the thickness direction, and slope portions located outside the arc-shaped portions in the thickness direction and continuously connected to the arc-shaped portions, and a straight portion having a thickness equal to or greater than the thickness of the workpiece between the arc-shaped portions at both ends, the method comprising the steps of: disposing the workpiece and the grinding wheel parallel to each other; and rotating the grinding wheel and rotating the workpiece about a rotation axis parallel to the rotation axis of the grinding wheel, while moving the grinding wheel relatively to the workpiece in accordance with movement conditions calculated based on the radius of curvature of the arc-shaped portions of the grinding wheel so that a contact portion between the concave grinding portion and the workpiece moves along the desired cross-sectional shape of the workpiece, The step of moving the grinding wheel relative to the workpiece includes: while rotating the workpiece and the grinding wheel, moving the arc-shaped portion of the concave grinding portion of the grinding wheel in a curved line relative to the workpiece from the outer peripheral end face of the workpiece toward one surface by an angle calculated in advance in accordance with the movement conditions, thereby grinding the outer periphery of the one surface side of the workpiece; moving the grinding wheel along the outer peripheral end face of the workpiece from the one surface side to the other surface side of the workpiece, while rotating the workpiece and the grinding wheel, moving the arc-shaped portion of the concave grinding portion of the grinding wheel in a curved line relative to the workpiece from the outer peripheral end face of the workpiece toward the other surface by an angle calculated in advance in accordance with the movement conditions, thereby grinding the outer periphery of the other surface side of the workpiece,When performing rough grinding of the outer periphery of the one surface side or the other surface side of the workpiece, while rotating the workpiece and the grinding wheel, the arc-shaped portion of the concave grinding portion of the grinding wheel is moved in a curved line relative to the workpiece from the outer periphery end surface of the workpiece toward the one surface or the other surface by an angle calculated in advance in accordance with the movement conditions so that the rotation axis of the grinding wheel and the rotation axis of the workpiece are positioned in the same plane, and then the movement of the grinding wheel relative to the workpiece is stopped; A workpiece processing method characterized in that, when performing precision grinding of the outer periphery of the one surface side or the other surface side of the workpiece, while rotating the workpiece and the grinding wheel, the arc-shaped portion of the concave grinding portion of the grinding wheel is moved in a curved manner relative to the workpiece from the outer peripheral end face of the workpiece toward the one surface or the other surface by an angle calculated in advance in accordance with the movement conditions so that the rotation axis of the grinding wheel and the rotation axis of the workpiece are positioned in the same plane, and then the grinding wheel is moved linearly relative to the workpiece while maintaining the state in which the rotation axis of the grinding wheel and the rotation axis of the workpiece are positioned in the plane in which they were positioned during the curved movement.

[0099] [Appendix 17] A workpiece machining method for forming a disc-shaped workpiece into a desired cross-sectional shape using a rotatable, disc-shaped grinding wheel having a concave grinding portion on its outer periphery, the cross-sectional shape of the concave grinding portion in a cross section along the rotation axis of the grinding wheel being concave from the outer periphery toward the inner periphery, the concave grinding portion having arc-shaped portions at least at both ends in the thickness direction, and a straight portion having a thickness equal to or greater than the thickness of the workpiece between the arc-shaped portions at both ends, the method comprising the steps of: disposing the workpiece and the grinding wheel parallel to each other; and rotating the grinding wheel and rotating the workpiece about an axis of rotation parallel to the axis of rotation of the grinding wheel, while moving the grinding wheel relatively to the workpiece in accordance with movement conditions calculated based on a radius of curvature of the arc-shaped portion of the grinding wheel so that a contact portion between the concave grinding portion and the workpiece moves along the desired cross-sectional shape of the workpiece, the step of moving the grinding wheel relatively to the workpiece comprising: the outer periphery of the one surface side of the workpiece by moving the arc-shaped portion of the concave grinding portion of the grinding wheel in a curved line relative to the workpiece from the outer periphery end face of the workpiece toward one surface by an angle calculated in advance in accordance with the movement conditions while rotating the workpiece and the grinding wheel; moving the grinding wheel along the outer periphery end face of the workpiece from the one surface side to the other surface side relative to the workpiece; and the outer periphery of the other surface side of the workpiece by moving the arc-shaped portion of the concave grinding portion of the grinding wheel in a curved line relative to the workpiece from the outer periphery end face of the workpiece toward the other surface by an angle calculated in advance in accordance with the movement conditions while rotating the workpiece and the grinding wheel. When performing rough grinding of the outer periphery of the one surface side or the other surface side of the workpiece, while rotating the workpiece and the grinding wheel, the arc-shaped portion of the concave grinding portion of the grinding wheel is moved in a curved line relative to the workpiece from the outer periphery end surface of the workpiece toward the one surface or the other surface by an angle calculated in advance in accordance with the movement conditions, and then the movement of the grinding wheel relative to the workpiece is stopped;When performing precision grinding of the outer periphery of the one surface side or the other surface side of the workpiece, while rotating the workpiece and the grindstone, the arc-shaped portion of the concave grinding portion of the grindstone is moved in a curved line relative to the workpiece from the outer periphery end surface of the workpiece toward the one surface or the other surface by an angle calculated in advance in accordance with the movement conditions, and then the movement is stopped; When performing precision grinding of the outer periphery of the one surface side of the workpiece, while rotating the workpiece and the grinding wheel, the arc-shaped portion of the concave grinding portion of the grinding wheel is moved in a curved line relative to the workpiece from the outer peripheral end face of the workpiece toward the one surface by an angle calculated in advance in accordance with the movement conditions, taking into account a positional error in the thickness direction that occurs when the workpiece rotates, and then the movement is stopped, and the workpiece is rotated at least one revolution while adjusting the position in the thickness direction of the workpiece at a position where the grinding wheel contacts the slope of the chamfered portion on the one surface side of the workpiece, thereby grinding the one surface side of the workpiece while canceling out the positional error during rotation of the workpiece, a grinding wheel that moves the workpiece in a curved line from the outer peripheral end face of the workpiece toward the other surface by a predetermined angle in accordance with the movement conditions, based on the outermost position on the other surface in the thickness direction through which the workpiece passes during rotation, taking into account a positional error in the thickness direction that occurs during rotation of the workpiece, and then the movement is stopped; and the workpiece is rotated at least one full rotation at a slower rotation speed while adjusting the position of the workpiece in the thickness direction at a position where the grinding wheel contacts the slope of the chamfered portion on the other surface of the workpiece, thereby grinding the other surface of the workpiece while canceling out the positional error during rotation of the workpiece.

[0100] REFERENCE SIGNS LIST 1 Workpiece processing device 2 Workpiece 2a Chamfered portion 2b One side surface (surface to be adsorbed) 3, 6, 14 Rotation axis 4 Workpiece support mechanism 4a X-direction moving stage 4b ​​Y-direction moving stage 4c Z-direction moving stage 4d Motor 5 Grinding stone 5a Base disk portion 5b Concave grinding portion 5c Mounting hole 5d Recess 5e Arc-shaped portion 5f Straight portion 5g Cross-sectionally rectangular grinding portion 5h Sloped portion 7 Grinding stone support mechanism 7a Case 7b Rotation bearing portion 7c Spindle 7d Flange portion 7e Bolt 10 Adsorption member 10a Thin-tipped shape 11 Truing grinding stone (truer) 12 Grooved grinding stone 12a Groove 13 Grooved grinding stone support mechanism 15 Temperature adjustment mechanism 16 Grinding stone 16a Formed groove

Claims

1. A workpiece processing device for forming a disk-shaped workpiece into a desired cross-sectional shape, comprising: a workpiece support mechanism for supporting the workpiece; a disk-shaped grinding wheel arranged parallel to the workpiece; and a grinding wheel support mechanism for supporting the grinding wheel, wherein the workpiece support mechanism rotates the workpiece, and the grinding wheel support mechanism rotates the grinding wheel, and the rotation axis around which the workpiece is rotated by the workpiece support mechanism and the rotation axis around which the grinding wheel is rotated by the grinding wheel support mechanism are parallel to each other, the workpiece support mechanism has an adsorption member for adsorbing only one side of the workpiece, the planar shape of the adsorption member is a circle with a radius smaller than the radius of the workpiece, and the outer periphery of the circular adsorption member has a tapered shape that becomes thinner as it goes outward, the grinding wheel has a concave grinding portion on its outer periphery, the cross-sectional shape of the concave grinding portion in a cross section along the rotation axis of the grinding wheel is concave recessed from the outer periphery toward the inner periphery, and has an arc-shaped portion at least at both ends in the thickness direction, and has a straight portion between the arc-shaped portions at both ends, the straight portion having a thickness equal to or greater than the thickness of the workpiece and performing grinding for at least one of reducing the diameter of the workpiece and smoothing the middle portion of the outer periphery in the thickness direction of the workpiece; the grinding wheel and the workpiece can be moved relatively to each other by the grinding wheel support mechanism or the workpiece support mechanism so as to move toward or away from each other; the grinding wheel support mechanism or the workpiece support mechanism moves the grinding wheel relative to the workpiece in accordance with movement conditions calculated based on the radius of curvature of the arc-shaped portion of the grinding wheel so that a contact portion between the concave grinding portion and the workpiece moves along the desired cross-sectional shape of the workpiece; a radius of curvature of the arc-shaped portion of the grindstone is at least 10 times the thickness of the workpiece so that the arc-shaped portion of the grindstone abuts against the workpiece without generating a substantial gap between the arc-shaped portion and the chamfered portion of the desired cross-sectional shape of the workpiece;a workpiece machining device, characterized in that the arc-shaped portion located on the one side of the workpiece that is adsorbed by the suction member has a length, in a cross section along the rotation axis of the grinding wheel, that is greater than or equal to the length of the chamfered portion on the one side of the workpiece having the desired cross-sectional shape, and is less than the length at which the tangent of the arc-shaped portion abuts against the tapered shape of the suction member when in contact with the end of the one side of the workpiece at a position where it extends at an angle that matches the angle of the tapered shape of the suction member.

2. A workpiece processing device for forming a disk-shaped workpiece into a desired cross-sectional shape, comprising: a workpiece support mechanism for supporting the workpiece; a disk-shaped grinding wheel arranged parallel to the workpiece; and a grinding wheel support mechanism for supporting the grinding wheel, wherein the workpiece support mechanism rotates the workpiece, and the grinding wheel support mechanism rotates the grinding wheel, and the rotation axis around which the workpiece is rotated by the workpiece support mechanism and the rotation axis around which the grinding wheel is rotated by the grinding wheel support mechanism are parallel to each other, the workpiece support mechanism has an adsorption member for adsorbing only one side of the workpiece, the planar shape of the adsorption member is a circle with a radius smaller than the radius of the workpiece, and the outer periphery of the circular adsorption member has a tapered shape that becomes thinner toward the outside, the grinding wheel has a concave grinding portion on its outer periphery, the cross-sectional shape of the concave grinding portion in a cross section along the rotation axis of the grinding wheel is concave recessed from the outer periphery toward the inner periphery, and has at least an arc-shaped portion at each end in the thickness direction, and a slope portion located outside the arc-shaped portion in the thickness direction and continuously connected to the arc-shaped portion, and between the arc-shaped portions at both ends, a straight portion having a thickness equal to or greater than the thickness of the workpiece and performing grinding for at least one of reducing the diameter of the workpiece and smoothing the middle portion in the thickness direction of the outer periphery of the workpiece, the slope portion extends along a tangent direction of the arc-shaped portion at a boundary position between the arc-shaped portion and the slope portion, which coincides with the angle of the chamfered portion on one face side of the workpiece having the desired cross-sectional shape, the grinding wheel and the workpiece are relatively movable toward and away from each other by the grinding wheel support mechanism or the workpiece support mechanism, the grindstone support mechanism or the workpiece support mechanism moves the grindstone relative to the workpiece in accordance with a movement condition calculated based on a radius of curvature of the arc-shaped portion of the grindstone so that a contact portion between the concave grinding portion and the workpiece moves along the desired cross-sectional shape of the workpiece, the radius of curvature of the arc-shaped portion of the grindstone being at least 10 times the thickness of the workpiece,a workpiece machining device, characterized in that the inclined portion located on the one side of the workpiece that is attracted by the suction member has a length that is greater than or equal to the length of the chamfered portion on the one side of the workpiece having the desired cross-sectional shape, in a cross section along the rotation axis of the grinding wheel, and when the angle in which the inclined portion extends with respect to the one side of the workpiece is smaller than the angle that the tapered shape of the suction member forms with respect to the one side of the workpiece, the inclined portion has a length that is less than the length at which the inclined portion abuts the tapered shape of the suction member when in contact with the end of the one side of the workpiece at a position where a tangent to the arc-shaped portion extends at an angle that matches the angle of the tapered shape of the suction member.

3. A workpiece processing device as described in claim 1 or 2, wherein the concave grinding portion and a cross-sectionally rectangular grinding portion whose surface facing the workpiece is linear and parallel to the thickness direction of the grinding wheel in a cross section along the rotation axis are arranged side by side on the outer periphery of the grinding wheel in the thickness direction, and the cross-sectionally rectangular grinding portion of the grinding wheel abuts against the outer periphery of the workpiece before grinding is performed by the concave grinding portion, and grinds the workpiece so as to reduce the radius of the workpiece by moving the grinding wheel from the radial outside to the radial inside of the workpiece.

4. A workpiece machining device as described in claim 1 or 2, wherein a radius r1 of the suction member, when expressed in terms of a radius r2 of the desired cross-sectional shape of the workpiece and a thickness t of the workpiece, satisfies r2-10t≦r1≦r2-5t, and an angle θ1 of the tapered shape of the suction member, when expressed in terms of an angle θ2 of the chamfered portion of the desired cross-sectional shape of the workpiece, satisfies θ2-10≦θ1≦θ2+5.

5. A workpiece processing device as described in claim 1 or 2, wherein the grinding wheel support mechanism has a spindle to which the grinding wheel is directly or indirectly attached, and a rotary bearing portion which rotatably supports the spindle, and supports the grinding wheel so that the center of gravity of the grinding wheel is located between the attachment position of the grinding wheel and the rotary bearing portion.

6. When grinding the outer periphery on one side of the workpiece, the grindstone support mechanism and the workpiece support mechanism rotate the workpiece and the grindstone, while moving the arc-shaped portion of the concave grinding portion of the grindstone in a curved manner relative to the workpiece from the outer periphery end face of the workpiece toward one side by an angle calculated in advance in accordance with the movement conditions, and when grinding the outer periphery on the other side of the workpiece, while rotating the workpiece and the grindstone, move the arc-shaped portion of the concave grinding portion of the grindstone in a curved manner relative to the workpiece from the outer periphery end face of the workpiece toward the other side by an angle calculated in advance in accordance with the movement conditions, The workpiece processing device according to claim 1 or 2, wherein, when performing rough grinding of the outer periphery of the one surface side or the other surface side of the workpiece, the grindstone support mechanism and the workpiece support mechanism rotate the workpiece and the grindstone, move the arc-shaped portion of the concave grinding portion of the grindstone curvilinearly relative to the workpiece from the outer periphery end face of the workpiece toward the one surface side or the other surface by an angle calculated in advance in accordance with the movement conditions, and then stop the movement of the grindstone relative to the workpiece; and, when performing precise grinding of the outer periphery of the one surface side or the other surface side of the workpiece, the grindstone support mechanism and the workpiece support mechanism rotate the workpiece and the grindstone, move the arc-shaped portion of the concave grinding portion of the grindstone curvilinearly relative to the workpiece from the outer periphery end face of the workpiece toward the one surface side or the other surface side of the workpiece by an angle calculated in advance in accordance with the movement conditions, and then move the grindstone linearly relative to the workpiece.

7. A workpiece processing device as described in claim 1 or 2, further comprising, in addition to the grinding wheel having the concave grinding portion, a disk-shaped grooved grinding wheel arranged at an angle to the tangent direction of the outer periphery of the workpiece and used for more precise grinding than grinding by the concave grinding portion of the grinding wheel, and a grooved grinding wheel support mechanism for supporting the grooved grinding wheel, wherein the grooved grinding wheel support mechanism rotates the grooved grinding wheel.

8. The workpiece processing device as described in claim 7, further comprising a truing grindstone that can be attached to the workpiece support mechanism in place of the workpiece, wherein the truing grindstone has an outer shape formed by being moved relative to the grindstone by the grindstone support mechanism or the workpiece support mechanism in accordance with the movement conditions, and the grooved grindstone has a groove formed or shaped by being pressed against the truing grindstone and the outer shape of the truing grindstone being transferred thereto.

9. A workpiece machining device as described in claim 1 or 2, wherein the workpiece support mechanism has a temperature adjustment mechanism that generates a flow of liquid or gas to keep the temperature of the rotating shaft of the workpiece support mechanism constant.

10. A grinding wheel included in the workpiece processing device described in claim 1 or 2, characterized in that the straight portion has a coarser grinding grain size than the arc-shaped portion, and the arc-shaped portion is used for more precise grinding than grinding using the straight portion.

11. A grinding wheel included in the workpiece processing device described in claim 3, characterized in that the grinding portion having a rectangular cross section is a portion having a coarser grinding grain size than the concave grinding portion, and the concave grinding portion is a portion used for more precise grinding than grinding by the grinding portion having a rectangular cross section.

12. A grinding wheel included in the workpiece processing device described in claim 1 or 2, characterized in that the arc-shaped portion at one end in the thickness direction and the arc-shaped portion at the other end are individually formed so that the average value of the radius of curvature of each is a desired size.

13. A grinding wheel included in the workpiece processing device described in claim 1 or 2, characterized in that the difference between the maximum and minimum values ​​of the radius of curvature of the arc-shaped portion at one end in the thickness direction and the difference between the maximum and minimum values ​​of the radius of curvature of the arc-shaped portion at the other end are both less than a first predetermined value, and the difference between the average value of the radius of curvature of the arc-shaped portion at one end in the thickness direction and the average value of the radius of curvature of the arc-shaped portion at the other end is less than a second predetermined value.

14. A grinding wheel included in the workpiece processing device according to claim 1 or 2, characterized in that the grinding wheel has a straight or tapered mounting hole extending in the thickness direction.

15. A method for machining a disc-shaped workpiece into a desired cross-sectional shape using a grinding wheel having a concave grinding portion on its outer periphery and a rotatable disc-shaped grinding wheel, the concave grinding portion having a cross-sectional shape in a cross section along the rotation axis of the grinding wheel that is concave from the outer periphery toward the inner periphery, at least both ends in the thickness direction of the grinding wheel having arc-shaped portions, and a straight portion between the arc-shaped portions at both ends that has a thickness equal to or greater than the thickness of the workpiece and performs grinding to at least one of reduce the diameter of the workpiece and smooth the middle portion of the outer periphery in the thickness direction of the workpiece, the method comprising the steps of: disposing the workpiece and the grinding wheel parallel to each other; and rotating the grinding wheel and rotating the workpiece about a rotation axis parallel to the rotation axis of the grinding wheel, while moving the grinding wheel relatively to the workpiece in accordance with a movement condition calculated based on a radius of curvature of the arc-shaped portion of the grinding wheel so that a contact portion between the concave grinding portion and the workpiece moves along the desired cross-sectional shape of the workpiece, The step of moving the grinding wheel relative to the workpiece includes: rotating the grinding wheel and the workpiece, only one side of which is attracted by an attraction member, to move the arc-shaped portion of the concave grinding portion of the grinding wheel in a curved manner from the outer peripheral end face of the workpiece toward one side by an angle calculated in advance in accordance with the movement conditions, thereby grinding the outer periphery of the one side of the workpiece to form a chamfered portion of the desired cross-sectional shape of the workpiece; moving the grinding wheel along the outer peripheral end face of the workpiece from the one side to the other side of the workpiece, relative to the workpiece; and rotating the workpiece and the grinding wheel to move the arc-shaped portion of the concave grinding portion of the grinding wheel in a curved manner from the outer peripheral end face of the workpiece toward the other side by an angle calculated in advance in accordance with the movement conditions, thereby grinding the outer periphery of the other side of the workpiece to form a chamfered portion of the desired cross-sectional shape of the workpiece.the planar shape of the suction member is a circle having a radius smaller than the radius of the workpiece, the outer peripheral portion of the circular suction member has a tapered shape that becomes thinner toward the outside, and the radius of curvature of the arc-shaped portion of the grinding wheel is at least 10 times the thickness of the workpiece so that the arc-shaped portion of the grinding wheel abuts against the workpiece without creating a substantial gap between the arc-shaped portion and the chamfered portion of the desired cross-sectional shape of the workpiece, the arc-shaped portion located on the one surface side of the workpiece that is attracted by the suction member has a length that is equal to or longer than the length of the chamfered portion of the one surface side of the workpiece having the desired cross-sectional shape in a cross section along the rotation axis of the grinding wheel, and is less than the length at which the arc-shaped portion abuts against the tapered shape of the suction member in a state in which it is in contact with the end of the one surface side of the workpiece at a position where a tangent of the arc-shaped portion extends at an angle that matches the angle of the tapered shape of the suction member, When performing rough grinding of the outer periphery of the one surface side or the other surface side of the workpiece, while rotating the workpiece and the grindstone, the arc-shaped portion of the concave grinding portion of the grindstone is moved in a curved manner relative to the workpiece from the outer periphery end face of the workpiece toward the one surface or the other surface by an angle calculated in advance according to the movement conditions so that the rotation axis of the grindstone and the rotation axis of the workpiece are positioned in the same plane, and then the relative movement of the grindstone with respect to the workpiece is stopped; A workpiece machining method, characterized in that, when performing precise grinding of the outer periphery of the one surface side or the other surface side of the workpiece, while rotating the workpiece and the grinding wheel, the arc-shaped portion of the concave grinding portion of the grinding wheel is moved curvilinearly relative to the workpiece from the outer periphery end face of the workpiece toward the one surface side or the other surface side by an angle calculated in advance in accordance with the movement conditions so that the rotation axis of the grinding wheel and the rotation axis of the workpiece are positioned in the same plane, and then the grinding wheel is moved linearly relative to the workpiece so that the rotation axis of the grinding wheel and the rotation axis of the workpiece move relatively in a plane extending in a direction intersecting perpendicularly or obliquely to the plane in which the rotation axis of the grinding wheel and the rotation axis of the workpiece were positioned during the curvilinear movement.

16. A method for machining a disc-shaped workpiece into a desired cross-sectional shape using a grinding wheel having a concave grinding portion on its outer periphery, the concave grinding portion having a cross-sectional shape recessed from the outer periphery toward the inner periphery in a cross section along the rotation axis of the grinding wheel, the grinding wheel having an arc-shaped portion at least at both ends in the thickness direction and a slope portion located outside the arc-shaped portion in the thickness direction and continuously connected to the arc-shaped portion, and a straight portion having a thickness equal to or greater than the thickness of the workpiece and performing grinding for at least one of reducing the diameter of the workpiece and smoothing the middle portion of the outer periphery of the workpiece in the thickness direction, comprising the steps of: arranging the workpiece and the grinding wheel parallel to each other; the step of rotating the grindstone and rotating the workpiece about a rotation axis parallel to the rotation axis of the grindstone, while moving the grindstone relative to the workpiece in accordance with movement conditions calculated based on a radius of curvature of the arc-shaped portion of the grindstone so that a contact portion between the concave grinding portion and the workpiece moves along the desired cross-sectional shape of the workpiece, wherein the step of moving the grindstone relative to the workpiece includes: rotating the grindstone and the workpiece, only one side of which is attracted by an attraction member, while moving the arc-shaped portion of the concave grinding portion of the grindstone curvedly relative to the workpiece from the outer peripheral end face of the workpiece toward one side by an angle calculated in advance in accordance with the movement conditions, thereby grinding the outer periphery of the one side of the workpiece to form a chamfered portion of the desired cross-sectional shape of the workpiece; and moving the grindstone relative to the workpiece along the outer periphery end face of the workpiece from the one side to the other side. and rotating the workpiece and the grindstone, and moving the arc-shaped portion of the concave grinding portion of the grindstone in a curved manner from the outer peripheral end face of the workpiece toward the other surface by an angle calculated in advance according to the movement conditions, thereby grinding the outer peripheral portion of the workpiece on the other surface side to form a chamfered portion of the workpiece having the desired cross-sectional shape,the planar shape of the suction member is a circle with a radius smaller than the radius of the workpiece, the outer peripheral portion of the circular suction member has a tapered shape that becomes thinner toward the outside, the radius of curvature of the arc-shaped portion of the grinding wheel is at least 10 times the thickness of the workpiece, the inclined portion extends along a tangent direction of the arc-shaped portion at a boundary position between the arc-shaped portion and the inclined portion, which coincides with the angle of the chamfered portion on one side of the workpiece having the desired cross-sectional shape, the inclined portion located on the one surface side of the workpiece that is attracted by the attraction member has a length that is equal to or longer than the length of the chamfered portion on the one surface side of the workpiece having the desired cross-sectional shape in a cross section along the rotation axis of the grindstone, and when the angle formed by the direction in which the inclined portion extends with respect to the one surface of the workpiece is smaller than the angle formed by the tapered shape of the attraction member with respect to the one surface of the workpiece, the inclined portion has a length that is less than the length at which the inclined portion abuts against the tapered shape of the attraction member in a state in which the inclined portion is in contact with the end portion on the one surface side of the workpiece at a position where a tangent to the arc-shaped portion extends at an angle that coincides with the angle of the tapered shape of the attraction member, When performing rough grinding of the outer periphery of the one surface side or the other surface side of the workpiece, while rotating the workpiece and the grindstone, the arc-shaped portion of the concave grinding portion of the grindstone is moved in a curved manner relative to the workpiece from the outer periphery end face of the workpiece toward the one surface or the other surface by an angle calculated in advance according to the movement conditions so that the rotation axis of the grindstone and the rotation axis of the workpiece are positioned in the same plane, and then the relative movement of the grindstone with respect to the workpiece is stopped;A workpiece machining method, characterized in that, when performing precise grinding of the outer periphery of the one surface side or the other surface side of the workpiece, while rotating the workpiece and the grinding wheel, the arc-shaped portion of the concave grinding portion of the grinding wheel is moved curvilinearly relative to the workpiece from the outer periphery end face of the workpiece toward the one surface side or the other surface side by an angle calculated in advance in accordance with the movement conditions so that the rotation axis of the grinding wheel and the rotation axis of the workpiece are positioned in the same plane, and then the grinding wheel is moved linearly relative to the workpiece while maintaining the state in which the rotation axis of the grinding wheel and the rotation axis of the workpiece are positioned within the plane in which the rotation axis of the grinding wheel and the rotation axis of the workpiece were positioned during the curvilinear movement.

17. A method for machining a disc-shaped workpiece into a desired cross-sectional shape using a grinding wheel having a concave grinding portion on its outer periphery and a rotatable disc-shaped grinding wheel, the concave grinding portion having a cross-sectional shape in a cross section along the rotation axis of the grinding wheel that is concave from the outer periphery toward the inner periphery, at least both ends in the thickness direction of the grinding wheel having arc-shaped portions, and a straight portion between the arc-shaped portions at both ends that has a thickness equal to or greater than the thickness of the workpiece and performs grinding to at least one of reduce the diameter of the workpiece and smooth an intermediate portion of the outer periphery in the thickness direction of the workpiece, the method comprising the steps of: disposing the workpiece and the grinding wheel parallel to each other; and rotating the grinding wheel and rotating the workpiece about a rotation axis parallel to the rotation axis of the grinding wheel, while moving the grinding wheel relatively to the workpiece in accordance with a movement condition calculated based on a radius of curvature of the arc-shaped portion of the grinding wheel so that a contact portion between the concave grinding portion and the workpiece moves along the desired cross-sectional shape of the workpiece, The step of moving the grinding wheel relative to the workpiece includes: rotating the grinding wheel and the workpiece, only one side of which is attracted by an attraction member, to move the arc-shaped portion of the concave grinding portion of the grinding wheel in a curved manner from the outer peripheral end face of the workpiece toward one side by an angle calculated in advance in accordance with the movement conditions, thereby grinding the outer periphery of the one side of the workpiece to form a chamfered portion of the desired cross-sectional shape of the workpiece; moving the grinding wheel along the outer peripheral end face of the workpiece from the one side to the other side of the workpiece, relative to the workpiece; and rotating the workpiece and the grinding wheel to move the arc-shaped portion of the concave grinding portion of the grinding wheel in a curved manner from the outer peripheral end face of the workpiece toward the other side by an angle calculated in advance in accordance with the movement conditions, thereby grinding the outer periphery of the other side of the workpiece to form a chamfered portion of the desired cross-sectional shape of the workpiece.the planar shape of the suction member is a circle having a radius smaller than the radius of the workpiece, the outer peripheral portion of the circular suction member has a tapered shape that becomes thinner toward the outside, and the radius of curvature of the arc-shaped portion of the grinding wheel is at least 10 times the thickness of the workpiece so that the arc-shaped portion of the grinding wheel abuts against the workpiece without creating a substantial gap between the arc-shaped portion and the chamfered portion of the desired cross-sectional shape of the workpiece, the arc-shaped portion located on the one surface side of the workpiece that is attracted by the suction member has a length that is equal to or longer than the length of the chamfered portion of the one surface side of the workpiece having the desired cross-sectional shape in a cross section along the rotation axis of the grinding wheel, and is less than the length at which the arc-shaped portion abuts against the tapered shape of the suction member in a state in which it is in contact with the end of the one surface side of the workpiece at a position where a tangent of the arc-shaped portion extends at an angle that matches the angle of the tapered shape of the suction member, When performing rough grinding of the outer periphery of the one surface side or the other surface side of the workpiece, while rotating the workpiece and the grindstone, the arc-shaped portion of the concave grinding portion of the grindstone is moved in a curved manner relative to the workpiece from the outer periphery end face of the workpiece toward the one surface side or the other surface by an angle calculated in advance according to the movement condition, and then the movement of the grindstone relative to the workpiece is stopped; When performing precise grinding of the outer periphery of the one surface side of the workpiece, while rotating the workpiece and the grindstone, the arc-shaped portion of the concave grinding portion of the grindstone is moved in a curved manner relative to the workpiece from the outer peripheral end face of the workpiece toward the one surface by an angle calculated in advance according to the movement conditions, taking into account a position error in the thickness direction that occurs when the workpiece rotates, and then the movement is stopped. At a position where the grindstone contacts the slope of the chamfered portion of the one surface side of the workpiece, the rotation speed of the workpiece is slowed down and the workpiece is rotated at least one revolution while adjusting the position in the thickness direction of the workpiece, thereby grinding the one surface side of the workpiece while canceling out the position error during the rotation of the workpiece.a grinding wheel that is rotated in a direction parallel to the outer periphery of the workpiece and a grinding wheel that is moved in a curved manner relative to the workpiece by an angle calculated in advance in accordance with the movement conditions from the outer periphery end face of the workpiece toward the other surface of the workpiece, based on the outermost position on the other surface side in the thickness direction through which the workpiece passes when rotating, taking into account a positional error in the thickness direction that occurs when the workpiece rotates, and then the movement is stopped.The rotation speed of the workpiece is slowed down and the workpiece is rotated at least one revolution while adjusting the position in the thickness direction of the workpiece at a position where the grinding wheel contacts the slope of the chamfered portion on the other surface side of the workpiece, thereby grinding the other surface side of the workpiece while canceling out the positional error during rotation of the workpiece.

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