How to process the workpiece

Abstract

To provide a new work-piece processing method that can easily process a work-piece with high accuracy.SOLUTION: In a work-piece processing method that is used in processing a work-piece with a disk-like blade including abrasive grain, an auxiliary plate made of materials which are higher in elastic modulus than materials constituting a surface side of the work-piece is arranged on the surface of the work-piece, the rotated blade is cut into the surface side of the work-piece to cut the work-piece together with the auxiliary plate, and the auxiliary plate is removed from the cut work-piece.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for machining a workpiece, which is used when machining a workpiece with a blade containing abrasive grains. [Background technology]

[0002] In the manufacturing process of piezoelectric elements used in vibrators, for example, grooves are formed in a workpiece containing a piezoelectric material (piezoelectric ceramics) such as lead zirconate titanate (PZT) by cutting a disc-shaped blade containing abrasive grains into the workpiece. By adjusting the width, depth, and spacing of the grooves, piezoelectric elements with various characteristics can be realized.

[0003] In order to achieve appropriate machining of workpieces containing piezoelectric materials, attempts have been made to optimize machining conditions from various perspectives (see, for example, Patent Document 1). For example, by appropriately adjusting the rotation speed of the blade cutting into the workpiece, the feed speed of the workpiece relative to the blade, the amount of water supplied to the workpiece, etc., it becomes possible to machine the workpiece without damaging it. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-27052 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to form deep grooves in a workpiece using the above-mentioned blade cutting method, the outer periphery of the blade must be sufficiently exposed from the disk-shaped base that secures the center of the blade. In other words, the distance from the edge of the base to the outer periphery of the blade (referred to as the cutting edge exposure) must be set sufficiently large.

[0006] On the other hand, if the distance from the edge of the base to the outer periphery of the blade is too large compared to the thickness of the blade, the blade will deform significantly in the thickness direction when cutting the workpiece, resulting in a decrease in cutting accuracy. This decrease in cutting accuracy is particularly noticeable when the surface side of the workpiece where the blade cuts is made of a soft material.

[0007] The present invention has been made in consideration of such problems, and its purpose is to provide a new method for processing a workpiece that makes it easy to process the workpiece with high precision when processing the workpiece with a blade containing abrasive grains. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a method for processing a workpiece used when processing a workpiece with a disc-shaped blade containing abrasive grains, which method comprises placing an auxiliary plate made of a material having a higher elastic modulus than the material constituting the surface side of the workpiece on the surface of the workpiece, rotating the blade to cut into the surface side of the workpiece and cut the workpiece together with the auxiliary plate, and removing the auxiliary plate from the workpiece after cutting.

[0009] In one embodiment of the present invention, it is preferable to use the auxiliary plate made of a material having a Young's modulus of 40 GPa or more at room temperature.

[0010] In one embodiment of the present invention, the blade may be caused to cut into the surface side of the workpiece under the condition that the value obtained by dividing the blade tip exposure by the blade thickness is 25 or more.

[0011] In one aspect of the present invention, the workpiece may be processed using a material containing piezoelectric ceramics.

[0012] In one embodiment of the present invention, ultrasonic vibration may be applied to the blade when the blade is rotated to cut into the front surface of the workpiece. [Effects of the Invention]

[0013] In one aspect of the present invention, a method for processing a workpiece includes placing an auxiliary plate made of a material with a higher elastic modulus than the material constituting the surface side of the workpiece on the surface of the workpiece, and cutting the workpiece together with the auxiliary plate by causing a rotating blade to cut into the surface side of the workpiece.Therefore, while the workpiece is being processed, the auxiliary plate, which is less likely to deform than the surface side of the workpiece, is located adjacent to the blade in the direction of the blade's thickness.

[0014] In other words, while the workpiece is being machined, the blade is sandwiched in its thickness direction by the auxiliary plate, which is difficult to deform, so the blade is less likely to deform in the thickness direction than when this auxiliary plate is not used. As a result, there is less chance of the accuracy of the workpiece being reduced due to blade deformation.

[0015] For example, the blade does not vibrate in the thickness direction (blade flapping), which would cause the width of the opening (upper end) of the formed groove to be significantly wider than the width of the bottom (lower end) of the groove. Furthermore, the blade does not bend, which would cause the groove to be formed at an angle. Therefore, the workpiece processing method according to one aspect of the present invention makes it easier to process the workpiece with high precision. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1(A) is a perspective view of the workpiece, and FIG. 1(B) is a cross-sectional view of the workpiece. [Figure 2] FIG. 2 is a perspective view showing the state in which an auxiliary plate is placed on the surface of a workpiece. [Figure 3] FIG. 3 is a cross-sectional view showing an example of the configuration of the cutting unit. [Figure 4]FIG. 4(A) is a side view showing how the workpiece is cut together with the auxiliary plate, and FIG. 4(B) is a cross-sectional view showing how the workpiece is cut together with the auxiliary plate. [Figure 5] FIG. 5(A) is a cross-sectional view showing the workpiece after cutting and before the auxiliary plate is removed, and FIG. 5(B) is a cross-sectional view showing the workpiece after the auxiliary plate has been removed. [Figure 6] FIG. 6 is a cross-sectional view showing an example of the configuration of a cutting unit according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0017] An embodiment of the present invention will be described with reference to the accompanying drawings. Fig. 1(A) is a perspective view of a workpiece 11 to be machined by a workpiece machining method according to this embodiment, and Fig. 1(B) is a cross-sectional view of the workpiece 11. As shown in Figs. 1(A) and 1(B), the workpiece 11 has a base portion 13 formed in a rectangular parallelepiped shape using piezoelectric ceramics such as lead zirconate titanate (PZT), lead titanate (PT), barium titanate, or bismuth titanate.

[0018] A first laminated portion 15 formed in a plate shape using a material such as resin or graphite is provided on a first surface 13a of the base portion 13. A second laminated portion 17 formed in a plate shape using a material such as tungsten carbide is provided on a second surface 13b of the base portion 13 located opposite the first surface 13a. In other words, the rectangular parallelepiped-shaped base portion 13 is sandwiched between the plate-shaped first laminated portion 15 and the plate-shaped second laminated portion 17.

[0019] The surface of the first laminated portion 15 that becomes the front surface 11a of the workpiece 11 is exposed on the side opposite the base portion 13 of the first laminated portion 15. Furthermore, the surface of the second laminated portion 17 that becomes the back surface 11b of the workpiece 11 is exposed on the side opposite the base portion 13 of the second laminated portion 17. In other words, the back surface 11b of the workpiece 11 is located on the side opposite the front surface 11a of the workpiece 11.

[0020] The front surface 11a and the back surface 11b of the workpiece 11 are both formed in a generally flat rectangular shape. The front surface 11a and the back surface 11b are disposed generally parallel to each other. The distance A1 between the front surface 11a and the back surface 11b (i.e., the thickness of the workpiece 11) is typically 1 mm or more. However, the distance A1 may be less than 1 mm.

[0021] In this embodiment, the workpiece 11 has a base portion 13, a first laminate portion 15, and a second laminate portion 17, but there are no particular limitations on the structure of the workpiece 11. For example, the workpiece 11 may be composed of only the base portion 13, or may include the base portion 13 and any number of laminate portions. Similarly, there are no particular limitations on the material that constitutes the workpiece 11. For example, the workpiece 11 may be formed using other piezoelectric materials, semiconductors, metals, resins, glass, ceramics, etc.

[0022] In the workpiece processing method according to this embodiment, first, an auxiliary plate is placed on the surface 11a of the workpiece 11 (auxiliary plate placing step). Fig. 2 is a perspective view showing the state in which the auxiliary plate 19 is placed on the surface 11a of the workpiece 11. As shown in Fig. 2, the auxiliary plate 19 is formed in the shape of a plate having a pair of surfaces that are approximately the same size as the surface 11a of the workpiece 11.

[0023] The auxiliary plate 19 is made of a material having a higher elastic modulus than the material constituting the surface 11a side of the workpiece 11 (in this embodiment, the first laminate portion 15). The elastic modulus is a value obtained by dividing the stress (external force) applied to the object by the amount of strain caused by this stress, and represents the relationship between stress and strain during elastic deformation.

[0024] As in this embodiment, when the auxiliary plate 19 is formed using a material with a higher elastic modulus than the material that forms the front surface 11a of the workpiece 11, when the same force is applied, the strain generated in the auxiliary plate 19 is smaller than the strain generated in the front surface 11a of the workpiece 11. In other words, the auxiliary plate 19 is less likely to deform than the front surface 11a of the workpiece 11.

[0025] As the modulus of elasticity, for example, Young's modulus (tensile modulus of elasticity) can be used. The Young's modulus at room temperature (300 K, 27° C.) of resin that may be used in the first laminate portion 15 of the workpiece 11 is typically less than 4 GPa. Furthermore, the Young's modulus at room temperature of graphite that may be used in the first laminate portion 15 is typically less than 20 GPa. Therefore, in this embodiment, for example, an auxiliary plate 19 formed of a material having a Young's modulus of 20 GPa or more at room temperature is used.

[0026] However, it is desirable that the Young's modulus of the material constituting the auxiliary plate 19 is sufficiently higher than the Young's modulus of the material constituting the surface 11a side (first stacked portion 15) of the workpiece 11. By making the Young's modulus of the material constituting the auxiliary plate 19 sufficiently higher than the Young's modulus of the material constituting the surface 11a side of the workpiece 11, the blade becomes less likely to deform in its thickness direction during subsequent processing using the blade.

[0027] Specifically, it is desirable to use an auxiliary plate 19 made of a material having a Young's modulus of 40 GPa or more at room temperature, and it is more desirable to use an auxiliary plate 19 made of a material having a Young's modulus of 60 GPa or more at room temperature. Examples of such materials include silicon having a Young's modulus of about 190 GPa at room temperature, silicon carbide having a Young's modulus of about 150 GPa to 600 GPa at room temperature, soda glass having a Young's modulus of about 70 to 75 GPa at room temperature, quartz glass having a Young's modulus of about 70 to 75 GPa at room temperature, and alumina having a Young's modulus of about 350 GPa to 400 GPa at room temperature.

[0028] However, there are no particular limitations on the specific material that constitutes the auxiliary plate 19. For example, the auxiliary plate 19 may be formed using a metal or the like that satisfies the above-mentioned Young's modulus relationship. In addition, in this embodiment, the material of the auxiliary plate 19 is determined based on Young's modulus, which is one type of elastic modulus, but the material of the auxiliary plate 19 can also be determined based on the shear modulus, bulk modulus, etc.

[0029] There is no particular limit to the thickness of the auxiliary plate 19. For example, by making the thickness of the auxiliary plate 19 50 μm or more, preferably 70 μm or more, the auxiliary plate 19 is less likely to break when machining the workpiece 11. Furthermore, by making the thickness of the auxiliary plate 19 150 μm or less, preferably 130 μm or less, the outer periphery of the blade to be used later is not exposed too much from the base. In this embodiment, an auxiliary plate 19 made of silicon and having a thickness of 100 μm is used.

[0030] When this auxiliary plate 19 is placed on the surface 11a of the workpiece 11, for example, an adhesive layer made of a temporary adhesive, wax, or the like is interposed between the surface 11a of the workpiece 11 and the auxiliary plate 19. By attaching and fixing the auxiliary plate 19 to the workpiece 11 in this way, the auxiliary plate 19 will not move when the workpiece 11 is machined, which will result in a decrease in machining accuracy.

[0031] After the auxiliary plate 19 is placed on the surface 11a of the workpiece 11, a disc-shaped blade containing abrasive grains is caused to cut into the surface 11a of the workpiece 11, cutting the workpiece 11 together with the auxiliary plate 19 (cutting step). Fig. 3 is a cross-sectional view showing an example of the configuration of the cutting unit 2 used when cutting the workpiece 11. Note that in Fig. 3, some of the components are shown as functional blocks.

[0032] As shown in Fig. 3, the cutting unit 2 includes a cylindrical spindle housing 4. A cylindrical spindle 6 that serves as a rotation axis is housed in the space inside the spindle housing 4. A plurality of air injection ports (not shown) that form an air bearing are provided on the inner wall surface of the spindle housing 4.

[0033] By injecting air from the air injection port toward the axis of the spindle 6, the position of the spindle 6 can be maintained in a direction perpendicular to the axis of the spindle 6. In addition, a flange-shaped (disk-shaped) thrust plate 6b is provided on the side surface 6a of the spindle 6. By injecting air from the air injection port toward this thrust plate 6b in a direction parallel to the axis of the spindle 6, the position of the spindle 6 can be maintained in a direction parallel to the axis of the spindle 6.

[0034] A motor 8 capable of generating a force to rotate the spindle 6 is connected to the base end of the spindle 6. The motor 8 includes a stator 8a fixed to the spindle housing 4 and a rotor 8b connected to the spindle 6. An external power supply 10 is connected to the stator 8a, and the rotor 8b rotates under the influence of a magnetic field generated by the stator 8a due to the power supplied from the power supply 10.

[0035] An opening 4a is formed at the tip of the spindle housing 4. The spindle 6 is inserted into the opening 4a so that its tip 6c is exposed from the spindle housing 4. Specifically, the tip 6c of the spindle 6 protrudes outward from the tip of the spindle housing 4.

[0036] A disk-shaped first mounter (base) 12 is fixed to the tip 6c of the spindle 6 exposed from the spindle housing 4. A boss (not shown) protruding, for example, from the center of the first mounter 12 is provided on the opposite side of the spindle 6. A disk-shaped blade 14 is attached to the first mounter 12, the blade having a hole in the center into which the boss is inserted.

[0037] The blade 14 has a pair of generally flat and parallel side surfaces, and is attached to the first mounter 12 so that the pair of side surfaces are perpendicular to the axis of the spindle 6. The blade 14 is typically formed by fixing abrasive grains such as diamond with a binder such as resin or metal.

[0038] With the blade 14 attached to the first mounter 12, a disk-shaped second mounter (base) 16 is further attached to the first mounter 12. Like the blade 14, the second mounter 16 also has a hole in the center into which a boss portion is inserted. When the second mounter 16 is attached to the first mounter 12, the blade 14 is sandwiched between the first mounter 12 and the second mounter 16.

[0039] With the second mounter 16 attached to the first mounter 12, a fixing nut 18 is fastened to the boss of the first mounter 12. As a result, the second mounter 16 is pressed toward the first mounter 12 by the fixing nut 18, and the blade 14 is fixed by being sandwiched between the first mounter 12 and the second mounter 16.

[0040] In this embodiment, a blade 14 with a high aspect ratio is used, where the value obtained by dividing the distance B1 (i.e., the cutting edge exposure amount of the blade 14) (see FIG. 4(A)) from the edge (outer peripheral edge) of the first mounter 12 and the second mounter 16 to the outer peripheral edge of the blade 14 by the thickness B2 (see FIG. 4(B)) of the blade 14 is 25 or more. This allows the outer peripheral portion of the blade 14 to be sufficiently exposed from the first mounter 12 and the second mounter 16 that secure the blade 14, making it possible to form a deep groove in the workpiece 11. However, the aspect ratio of the blade 14 is not limited to this.

[0041] Fig. 4(A) is a side view showing how the workpiece 11 is cut together with the auxiliary plate 19, and Fig. 4(B) is a cross-sectional view showing how the workpiece 11 is cut together with the auxiliary plate 19. When cutting the workpiece 11 using the cutting unit 2, for example, as shown in Fig. 4(A), the workpiece 11 is held by a chuck table 22 via adhesive tape 21. It is also possible to hold the workpiece 11 directly on the chuck table 22.

[0042] After the workpiece 11 is held by the chuck table 22, the rotated blade 14 is caused to cut into the surface 11a of the workpiece 11. Specifically, first, the orientation of the cutting unit 2 and / or the orientation of the chuck table 22 is adjusted so that a pair of side surfaces of the blade 14 are generally parallel to the intended processing line of the workpiece 11 held on the chuck table 22.

[0043] In addition, one or both of the height of the cutting unit 2 and the height of the chuck table 22 are adjusted so that the lower end of the blade 14 is positioned lower than the surface 11a of the workpiece 11 held on the chuck table 22 and higher than the back surface 11b of the workpiece 11 held on the chuck table 22.

[0044] Furthermore, one or both of the positions of the cutting unit 2 and the chuck table 22 are adjusted so that the position of the blade 14 and the position of the planned processing line are aligned along a direction perpendicular to the planned processing line of the workpiece 11 (the direction of the axis of the spindle 6). Thereafter, with the blade 14 rotated, the cutting unit 2 and the chuck table 22 are moved relatively along a direction parallel to the planned processing line of the workpiece 11 (the pair of side surfaces of the blade 14).

[0045] This allows the blade 14 to cut into the surface 11a of the workpiece 11, forming grooves 11c along the planned processing lines in the workpiece 11. Note that the workpiece 11 of this embodiment does not have a specific pattern or the like indicating the planned processing lines. Therefore, in this embodiment, the planned processing lines are defined, for example, by the distance from the end of the workpiece 11 to the position where the blade 14 is to cut in. The above-mentioned operation is repeated, for example, until grooves 11c are formed along all of the planned processing lines set in the workpiece 11.

[0046] In this embodiment, as described above, the blade 14 is caused to cut into the surface 11a side of the workpiece 11 under the condition of a high aspect ratio in which the value obtained by dividing the distance B1 by the thickness B2 is 25 or more. Therefore, a sufficiently deep groove 11c can be formed in the workpiece 11. For example, it is also possible to form a deep groove 11c in which the value obtained by dividing the depth A2 of the groove 11c by the width of the groove 11c (≈ the thickness B2 of the blade 14) is 20 or more.

[0047] On the other hand, when the blade 14 is caused to cut into the surface 11a of the workpiece 11 under such high aspect ratio conditions, the blade 14 is significantly deformed in the direction of its thickness (i.e., the direction perpendicular to the pair of side surfaces of the blade 14, the direction of the axis of the spindle 6), which tends to reduce the machining accuracy.

[0048] Specifically, for example, blade 14 cutting into workpiece 11 may vibrate in the thickness direction (blade 14 may flap), causing the width of the opening (upper end) of groove 11c to be significantly wider than the width of the bottom (lower end) of groove 11c. Also, for example, blade 14 cutting into workpiece 11 may bend, causing groove 11c to be formed at an angle.

[0049] Therefore, in this embodiment, an auxiliary plate 19 made of a material with a higher elastic modulus than the material composing the surface 11a of the workpiece 11 is placed on the surface 11a of the workpiece 11, and the workpiece 11 is cut by the blade 14 together with the auxiliary plate 19. As a result, while the workpiece 11 is being machined, the auxiliary plate 19, which is less likely to deform than the surface 11a of the workpiece 11, is located adjacent to the blade 14 in the thickness direction of the blade 14.

[0050] In other words, while the workpiece 11 is being machined, the blade 14 is sandwiched in its thickness direction by the auxiliary plate 19, which is difficult to deform, so the blade 14 is less likely to deform in the thickness direction than when the auxiliary plate 19 is not used. Therefore, there is less possibility that the machining accuracy of the workpiece 11 will decrease due to deformation of the blade 14.

[0051] After the blade 14 has cut into the surface 11a of the workpiece 11 along all of the intended processing lines and the workpiece 11 has been cut together with the auxiliary plate 19, the auxiliary plate 19 is removed from the workpiece 11 (removal step). Fig. 5(A) is a cross-sectional view showing the workpiece 11 after cutting and before the auxiliary plate 19 is removed, and Fig. 5(B) is a cross-sectional view showing the workpiece 11 after the auxiliary plate 19 has been removed.

[0052] When removing the auxiliary plate 19 from the workpiece 11, for example, the adhesive strength of the adhesive layer existing between the workpiece 11 and the auxiliary plate 19 may be reduced by heating or other methods, and then the auxiliary plate 19 may be peeled off from the workpiece 11. However, there are no particular limitations on the method for removing the auxiliary plate 19 from the workpiece 11. By removing the auxiliary plate 19, the workpiece 11 having multiple deep grooves 11c on the surface 11a side is completed.

[0053] As described above, in the workpiece processing method of this embodiment, an auxiliary plate 19 made of a material having a higher elastic modulus than the material constituting the surface 11a side of the workpiece 11 is placed on the surface 11a of the workpiece 11, and the rotating blade 14 is caused to cut into the surface 11a side of the workpiece 11 to cut the workpiece 11 together with the auxiliary plate 19.Therefore, while the workpiece 11 is being processed, the auxiliary plate 19, which is less likely to deform than the surface 11a side of the workpiece 11, is located adjacent to the blade 14 in the thickness direction of the blade 14.

[0054] In other words, while the workpiece 11 is being machined, the blade 14 is sandwiched in its thickness direction by the auxiliary plate 19, which is difficult to deform, so the blade 14 is less likely to deform in the thickness direction than when this auxiliary plate 19 is not used. As a result, there is less possibility that the accuracy of machining the workpiece 11 will decrease due to deformation of the blade 14. Therefore, the workpiece machining method according to this embodiment makes it easier to machine the workpiece 11 with high accuracy.

[0055] The present invention is not limited to the above-described embodiment and can be practiced with various modifications. For example, the above-described embodiment describes the use of a washer-type blade 14 that is clamped and fixed between the first mounter 12 and the second mounter 16. However, the workpiece 11 can also be machined in a similar manner when a hub-type blade that is fixed in advance to a disk-shaped base is used.

[0056] When using a hub-type blade, it is advisable to use a blade with a high aspect ratio, where the distance from the edge (outer periphery) of the disk-shaped base to the outer periphery of the blade (i.e., the amount of cutting edge exposure) divided by the blade thickness is 25 or more. This allows the outer periphery of the blade to be fully exposed from the disk-shaped base that secures the blade, making it possible to form deep grooves in the workpiece 11.

[0057] Furthermore, when the rotating blade cuts into the surface 11a of the workpiece 11, ultrasonic vibrations may be applied to the blade. Fig. 6 is a cross-sectional view showing an example of the configuration of a cutting unit 32 according to a modified example. Note that Fig. 6 shows some of the components as functional blocks. The basic structure of the cutting unit 32 according to this modified example is the same as the structure of the cutting unit 2 according to the above-described embodiment.

[0058] 6, the cutting unit 32 includes a cylindrical spindle housing 34. A cylindrical spindle 36, which serves as a rotation axis, is housed in the space inside the spindle housing 34. A plurality of air injection ports (not shown) that form an air bearing are provided on the inner wall surface of the spindle housing 34.

[0059] By injecting air from the air injection port toward the axis of the spindle 36, the position of the spindle 36 can be maintained in a direction perpendicular to the axis of the spindle 36. In addition, a flange-shaped (disk-shaped) thrust plate 36b is provided on a side surface 36a of the spindle 36. By injecting air from the air injection port toward this thrust plate 36b in a direction parallel to the axis of the spindle 36, the position of the spindle 36 can be maintained in a direction parallel to the axis of the spindle 36.

[0060] A motor 38 capable of generating a force to rotate the spindle 36 is connected to the base end of the spindle 36. The motor 38 includes a stator 38a fixed to the spindle housing 34 and a rotor 38b connected to the spindle 36. An external power supply 40 is connected to the stator 38a, and the rotor 38b rotates under the influence of a magnetic field generated by the stator 38a due to the power supplied from the power supply 40.

[0061] A rotary transformer 42 is disposed on the opposite side of rotor 38b from spindle 36. Rotary transformer 42 includes a stator 42a fixed to spindle housing 34 and a rotor 42b connected to rotor 38b (spindle 36). An external power supply 44 is connected to stator 42a, and power from power supply 44 is supplied to terminals of rotor 42b in a contactless manner via stator 42a.

[0062] An ultrasonic vibrator 46 is connected to the terminals of the rotor 42b. The ultrasonic vibrator 46 vibrates by AC power supplied from the power supply 44 via the stator 42a and the rotor 42b. In this embodiment, AC power is supplied from the power supply 44 at a frequency within a range in which the ultrasonic vibrator 46 generates ultrasonic vibrations.

[0063] An opening 34a is formed at the tip of the spindle housing 34. The spindle 36 is inserted into the opening 34a so that its tip 36c is exposed from the spindle housing 34. Specifically, the tip 36c of the spindle 36 protrudes outward from the tip of the spindle housing 34.

[0064] A disk-shaped first mounter (base) 52 is fixed to the tip 36c of the spindle 36 exposed from the spindle housing 34. A boss (not shown) protruding, for example, from the center of the first mounter 52 is provided on the opposite side of the spindle 36. A disk-shaped blade 54 having a hole in the center into which the boss is inserted is attached to this first mounter 52.

[0065] The blade 54 has a pair of generally flat and parallel side surfaces, and is attached to the first mounter 52 so that the pair of side surfaces are perpendicular to the axis of the spindle 36. The blade 54 is typically formed by fixing abrasive grains such as diamond with a binder such as resin or metal.

[0066] With the blade 54 attached to the first mounter 52, a disk-shaped second mounter (base) 56 is further attached to the first mounter 52. Like the blade 54, the second mounter 56 also has a hole in the center into which a boss portion is inserted. When the second mounter 56 is attached to the first mounter 52, the blade 54 is sandwiched between the first mounter 52 and the second mounter 56.

[0067] With the second mounter 56 attached to the first mounter 52, a fixing nut 58 is fastened to the boss portion of the first mounter 52. As a result, the second mounter 56 is pressed toward the first mounter 52 by the fixing nut 58, and the blade 54 is fixed by being sandwiched between the first mounter 52 and the second mounter 56. Therefore, the ultrasonic vibrations generated by the ultrasonic vibrator 46 are transmitted to the blade 54 via the spindle 6 and the like, and the blade 54 is instantly expanded and contracted in the radial direction by the ultrasonic vibrations.

[0068] When the blade 54 is caused to cut into the surface 11a of the workpiece 11, power is supplied from the power source 44 to the ultrasonic vibrator 46 to apply ultrasonic vibration to the blade 54. This allows the blade 54 to cut into the workpiece 11 as if striking it, making it easier to machine the workpiece 11.

[0069] However, when the blade 54 cuts into the workpiece 11 while applying ultrasonic vibrations, chipping tends to occur on the surface 11a of the workpiece 11. The auxiliary plate 19 placed on the surface 11a of the workpiece 11 has the function of suppressing chipping caused by the ultrasonic vibrations applied to the blade 54, so even in this modified example, high precision can be maintained in the processing of the workpiece 11.

[0070] The specific procedure for cutting the blade 54 into the workpiece 11 may be the same as the procedure according to the above-described embodiment. In this modification, the ultrasonic vibrator 46 is provided on the base end side of the spindle 6, but the ultrasonic vibrator 46 can also be provided on the blade 54.

[0071] In addition, the structures, methods, etc. according to the above-described embodiments and modifications can be modified and implemented without departing from the scope of the present invention. [Explanation of symbols]

[0072] 11: Workpiece 11a: Surface 11b: Back side 11c: Groove 13: Base part 13a: 1st page 13b: 2nd side 15: First laminated section 17: Second laminated section 19: Auxiliary plate 21: Adhesive tape 2: Cutting unit 4: Spindle housing 4a:Aperture 6: Spindle 6a: Side 6b: Thrust plate 6c:Tip 8: Motor 8a: Stator 8b: rotor 10: Power supply 12: First mounter 14: Blade 16: Second mounter 18: Nut 22: Chuck table 32: Cutting unit 34: Spindle housing 34a:Aperture 36: Spindle 36a: Side 36b: Thrust plate 36c:Tip 38: Motor 38a: Stator 38b: rotor 40: Power supply 42: Rotary transformer 42a: Stator 42b: rotor 44:Power supply 46: Ultrasonic vibrator 52: First Mounter 54: Blade 56: Second Mounter 58: Nut A1: Distance A2: Depth B1 :Distance B2: Thickness

Claims

1. A method for processing a workpiece used when processing a workpiece with a disc-shaped blade containing abrasive grains, comprising: an auxiliary plate made of a material having a higher elastic modulus than a material constituting the surface side of the workpiece is placed on the surface of the workpiece; The rotating blade is caused to cut into the surface side of the workpiece, cutting the workpiece together with the auxiliary plate; A method for machining a workpiece, comprising removing the auxiliary plate from the workpiece after cutting.

2. 2. The method for processing a workpiece according to claim 1, wherein the auxiliary plate is made of a material having a Young's modulus of 40 GPa or more at room temperature.

3. 3. A method for machining a workpiece according to claim 1, wherein the blade is caused to cut into the surface side of the workpiece under the condition that the value obtained by dividing the blade tip exposure by the thickness of the blade is 25 or more.

4. 4. The method for processing a workpiece according to claim 1, wherein the workpiece is formed using a material containing piezoelectric ceramics.

5. 5. The method for machining a workpiece according to claim 1, wherein ultrasonic vibration is applied to the blade when the blade is rotated to cut into the surface side of the workpiece.

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