JP2011148028A - Grinding wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding wheel capable of being mounted without replacing a wheel mount even if a diameter of a wheel base is specified according to frequency of ultrasonic vibration to be generated on a grindstone. <P>SOLUTION: The grinding wheel is provided at a lower end of a rotary spindle constituting a grinding means for grinding a workpiece mounted on a chuck table and detachably mounted on a lower surface of the wheel mount including a bolt insertion hole. It includes the wheel base, an annular grindstone mounted on a lower surface of the wheel base, and an annular ultrasonic vibrating means disposed at a position corresponding to the interior of the annular grindstone on the wheel base. The wheel base includes: a base body having a grindstone mounting part for mounting the grindstone and an ultrasonic vibrating means mounting part for mounting the ultrasonic vibrating means; an annular sidewall formed to rise from an outer periphery of the base body; and an annular attachment formed inward from an upper end of the annular sidewall. An internal threaded hole is formed at a position corresponding to the bolt insertion hole provided on the wheel mount on the annular attachment. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a grinding wheel for grinding a workpiece such as a semiconductor wafer, and more particularly to a grinding wheel for grinding while ultrasonically vibrating.

  In the semiconductor device manufacturing process, a plurality of regions are partitioned by dividing lines called streets arranged in a lattice pattern on the surface of a substantially wafer-shaped semiconductor wafer, and devices such as ICs, LSIs, etc. are partitioned in the partitioned regions. Form. Then, the semiconductor wafer is cut along the streets to divide the region in which the device is formed to manufacture individual semiconductor devices. In addition, optical device wafers with gallium nitride compound semiconductors laminated on the surface of a sapphire substrate are also divided into individual optical devices such as light emitting diodes and laser diodes by cutting along the streets, and are widely used in electrical equipment. ing. The wafer divided in this way is ground to a predetermined thickness by a grinding device before being cut along the street.

  The grinding apparatus includes a chuck table that holds a workpiece, and a grinding unit that grinds the workpiece held on the chuck table. The grinding means includes a rotating spindle, a wheel mount provided at the lower end of the rotating spindle, and a grinding wheel that is detachably attached to the lower surface of the wheel mount. And a plurality of grinding wheels mounted on the outer peripheral grinding wheel mounting portion on the lower surface of the wheel base, and the grinding wheel is pressed against the workpiece held on the chuck table while rotating the grinding wheel. Grind the workpiece.

  However, when the back surface of the wafer is ground with the grinding wheel of the grinding device, the grinding wheel is clogged and the grinding ability is lowered. In particular, when brittle hard materials such as sapphire, silicon nitride, lithium tantalate, and artic are ground, there is a problem that productivity is remarkably lowered due to a decrease in grinding ability due to clogging of a grinding wheel.

  In order to solve the above-described problems, ultrasonic vibration is applied to a wheel table that holds a grinding wheel of a grinding wheel that grinds a work piece held on the chuck table and a work piece held on the chuck table. A grinding wheel has been proposed in which ultrasonic vibration is applied to a grinding wheel held on a wheel base by mounting means and applying high-frequency power to the ultrasonic vibration means. (For example, refer to Patent Document 1.)

  The wheel base constituting the grinding wheel has an annular mounting portion formed upright on the upper surface of the outer peripheral portion, and a position corresponding to a bolt insertion hole formed in the wheel mount in the annular mounting portion. A female screw hole is provided in the wheel mount, and a fastening bolt disposed by inserting a bolt insertion hole formed in the wheel mount into the female screw hole is screwed to be attached to the wheel mount.

JP 2009-107065 A

  Therefore, in order to transmit the ultrasonic vibration generated by the ultrasonic vibration means mounted on the wheel base of the grinding wheel to the grinding wheel and generate the ultrasonic vibration having a desired vibration width in the grinding wheel, It is necessary to match the ultrasonic vibration generated by the sonic vibration means with the natural frequency of the wheel base. For this reason, the diameter of the wheel base increases depending on the frequency of the ultrasonic vibration to be generated in the grinding wheel, and there is a problem that the wheel mount must be replaced in accordance with the wheel base.

  The present invention has been made in view of the above facts, and its main technical problem is to replace the wheel mount even if the wheel base diameter is set in accordance with the frequency of the ultrasonic vibration to be generated on the grinding wheel. An object of the present invention is to provide a grinding wheel that can be mounted without any problems.

In order to solve the above main technical problem, according to the present invention, the lower surface of a wheel mount provided with a bolt insertion hole provided at the lower end of a rotary spindle constituting a grinding means for grinding a workpiece held on a chuck table. A grinding wheel detachably attached to the
A wheel base, an annular grinding wheel mounted on the lower surface of the wheel base, and an annular ultrasonic vibration means disposed at a position corresponding to the inside of the annular grinding wheel on the wheel base Become
The wheel base is erected from a base body including a grindstone mounting portion for mounting the grinding wheel and an ultrasonic vibration means mounting portion for mounting the ultrasonic vibration means, and an outer peripheral portion of the base main body. An annular side wall formed from the upper end of the annular side wall, and an annular attachment portion formed inward from the upper end of the annular side wall.
A female screw hole is formed at a position corresponding to the bolt insertion hole provided in the wheel mount in the annular mounting portion.
A grinding wheel is provided.

  In the base body of the wheel base, it is desirable that a plurality of arc-shaped slits are formed in the circumferential direction between the annular side wall and the grindstone mounting portion.

  A grinding wheel according to the present invention includes a base body having a grinding wheel mounting portion on which a wheel base mounts a grinding wheel and an ultrasonic vibration means mounting portion on which ultrasonic vibration means is mounted, and an outer peripheral portion of the base body. An annular side wall formed upright and an annular mounting portion formed inward from the upper end of the annular side wall, and a bolt provided on a wheel mount at the annular mounting portion Since the female screw hole is formed at a position corresponding to the insertion hole, it is possible to mount a grinding wheel having a different diameter without exchanging the wheel mount.

1 is a perspective view of a grinding apparatus equipped with a grinding wheel constructed according to the present invention. Sectional drawing of the spindle unit with which the grinding apparatus shown in FIG. 1 is equipped. The disassembled perspective view of the wheel mount and the grinding wheel which comprise the spindle unit shown in FIG. Sectional drawing of the grinding wheel shown in FIG. FIG. 4 is a bottom view of the grinding wheel shown in FIG. 3. Sectional drawing which shows the state which mounted | wore the wheel mount with the grinding wheel with a large diameter comprised according to this invention. The principal part side view which shows the state which is grinding the workpiece by the grinding apparatus shown in FIG.

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a grinding wheel constructed according to the present invention will be described in more detail with reference to the accompanying drawings.
FIG. 1 shows a perspective view of a grinding apparatus equipped with a grinding wheel constructed in accordance with the present invention. The grinding apparatus shown in FIG. 1 is provided with an apparatus housing generally indicated by numeral 2. This device housing 2 has a rectangular parallelepiped main portion 21 that extends long and an upright wall 22 that is provided at the rear end portion (upper right end in FIG. 1) of the main portion 21 and extends substantially vertically upward. ing. A pair of guide rails 221 and 221 extending in the vertical direction are provided on the front surface of the upright wall 22. A grinding unit 3 as grinding means is mounted on the pair of guide rails 221 and 221 so as to be movable in the vertical direction.

  The grinding unit 3 includes a moving base 31 and a spindle unit 4 mounted on the moving base 31. The movable base 31 is provided with a pair of legs 311 and 311 extending in the vertical direction on both sides of the rear surface. The pair of legs 311 and 311 is slidably engaged with the pair of guide rails 221 and 221. Guided grooves 312 and 312 are formed. As described above, a support portion 313 protruding forward is provided on the front surface of the movable base 31 slidably mounted on the pair of guide rails 221 and 221 provided on the upright wall 22. The spindle unit 4 is attached to the support portion 313.

  The spindle unit 4 includes a spindle housing 41 attached to the support portion 313 and a rotating spindle 42 that is rotatably disposed on the spindle housing 41. The spindle unit 4 will be described with reference to FIG. A spindle housing 41 constituting the spindle unit 4 shown in FIG. 2 is formed in a substantially cylindrical shape and includes a shaft hole 411 penetrating in the axial direction. A rotary spindle 42 that is inserted through a shaft hole 411 formed in the spindle housing 41 is provided with a thrust bearing flange 421 formed in the central portion so as to protrude in the radial direction. In this way, the rotary spindle 42 disposed through the shaft hole 411 formed in the spindle housing 41 is rotatably supported by high-pressure air supplied between the inner wall of the shaft hole 411. One end (lower end in FIG. 1) of the rotary spindle 42 rotatably supported by the spindle housing 41 is disposed so as to protrude from the lower end of the spindle housing 41, and a wheel mount is mounted on one end (lower end in FIG. 1). 43 is provided. Then, the grinding wheel 5 is attached to the lower surface of the wheel mount 43.

The wheel mount 43 and the grinding wheel 5 will be described with reference to FIGS.
As shown in FIG. 3, the wheel mount 43 is formed in a disc shape integrally with the lower end of the rotary spindle 42. The wheel mount 43 is provided with four bolt insertion holes 43a. A connector insertion hole 43 b is formed at the center of the wheel mount 43.

  A grinding wheel 5 shown in FIGS. 3 to 5 includes a disc-shaped wheel base 51 having a diameter (D1), an annular grinding wheel 52 mounted on the lower surface of the wheel base 51, and the wheel base. And an annular ultrasonic vibration means 6 disposed at a position corresponding to the inside of the annular grinding wheel 52 in 51. The wheel base 51 includes a base body 511 having a grindstone mounting portion 511a formed on the lower surface and mounted with the grinding wheel 52 and an ultrasonic vibration means mounting portion 511b formed on the upper surface and mounted with the ultrasonic vibration means 6. It comprises an annular side wall 512 formed upright from the outer periphery of the base body 511 and an annular mounting portion 513 formed inward from the upper end of the annular side wall 512. A plurality of arc-shaped slits 511c are formed in the base body 511 constituting the wheel base 51 so as to penetrate from the upper surface to the lower surface in the circumferential direction between the annular side wall 512 and the grindstone mounting portion 511a. An annular grinding stone 52 composed of a plurality of grinding stone segments is attached to the grinding stone attachment portion 511a of the base body 511 formed in this manner with an appropriate adhesive. In addition, the annular ultrasonic vibration means 6 is attached to the ultrasonic vibration means mounting portion 511b of the base body 511 with an appropriate adhesive. On the other hand, in the annular mounting portion 513, four female screw holes 513a are formed at positions corresponding to the bolt insertion holes 43a provided in the wheel mount 43.

  As shown in FIG. 4, the annular ultrasonic vibration means 6 attached to the ultrasonic vibration means attachment portion 511 b of the base body 511 includes an annular ultrasonic vibrator 61 and both-side polarization surfaces of the ultrasonic vibrator 61. And a pair of electrode plates 62a and 62b respectively attached to the two. The ultrasonic transducer 61 is formed in an annular shape from a piezoelectric ceramic such as barium titanate, lead zirconate titanate, or lithium tantalate. In the thus configured annular ultrasonic vibration means 6, one electrode plate 62a of the pair of electrode plates is attached to the ultrasonic vibration means attachment portion 511b with an insulating bond agent such as epoxy resin. In this way, one end of each of the conductive wires 63a and 63b is connected to the pair of electrode plates 62a and 62b constituting the annular ultrasonic vibration means 6 mounted on the ultrasonic vibration means mounting portion 511b of the base body 511. Has been. The other end of each conductive line 63a, 63b is connected to a convex connector 64 as shown in FIG. The convex connector 64 is detachably connected to a power supply means described later.

  In the grinding wheel 5 configured as described above, the fastening bolts 53 respectively inserted into the four bolt insertion holes 43 a provided in the wheel mount 43 are provided on the annular attachment portion 513 of the wheel base 51. Each screw hole 513a is screwed into the mounter 43 so as to be detachable.

Next, a grinding wheel having a natural frequency different from that of the grinding wheel 5 will be described with reference to FIG. The grinding wheel 50 shown in FIG. 6 has a diameter (D2 larger than the diameter (D1) of the grinding wheel 5. In FIG. 6, the wheel mount 43 is the wheel mount shown in FIGS. 6, the grinding wheel 50 shown in Fig. 6 has substantially the same configuration as the grinding wheel 5 except that the size is different. A description thereof will be omitted.
The annular attachment portion 513 constituting the wheel base 51 of the grinding wheel 50 shown in FIG. 6 is formed wider than the width of the annular attachment portion 513 constituting the wheel base 51 of the grinding wheel 5. The circumference is formed with substantially the same dimensions as the inner circumference of the annular mounting portion 513 constituting the wheel base 51 of the grinding wheel 5. A female screw hole 513 a is formed at a position corresponding to the bolt insertion hole 43 a provided in the wheel mount 43 in the annular mounting portion 513. Therefore, the grinding wheel 5 is threaded by screwing the fastening bolts 53 respectively inserted into the bolt insertion holes 43 a provided in the wheel mount 43 into the screw holes 513 a provided in the annular mounting portion 513 of the wheel base 51. The grinding wheel 50 having a diameter different from that of the mounter 43 can be detachably mounted.

  Returning to FIG. 2 and continuing the description, the spindle unit 4 in the illustrated embodiment includes an electric motor 7 for rotationally driving the rotary spindle 42. The illustrated electric motor 7 is constituted by a permanent magnet motor. The permanent magnet type electric motor 7 is disposed in the spindle housing 41 on the outer peripheral side of the rotor 71 and a rotor 71 made of a permanent magnet mounted on a motor mounting portion 422 formed in an intermediate portion of the rotary spindle 42. The stator coil 72 is included. In the electric motor 7 configured as described above, the rotor 71 is rotated by applying AC power to the stator coil 72 by power supply means described later, and the rotating spindle 42 to which the rotor 71 is mounted is rotated.

The spindle unit 4 in the illustrated embodiment includes power supply means 8 that applies high-frequency power to the ultrasonic transducer 61 and applies AC power to the electric motor 7.
The power supply means 8 includes a rotary transformer 80 disposed at the rear end of the spindle unit 4. The rotary transformer 80 includes a power receiving unit 81 disposed at the other end of the rotary spindle 42 and a power feeding unit 82 disposed opposite to the power receiving unit 81 and disposed at the rear end portion of the spindle housing 41. is doing. The power receiving means 81 includes a rotor side core 811 attached to the rotary spindle 42 and a power receiving coil 812 wound around the rotor side core 811. A conductive wire 813 is connected to the power receiving coil 812 of the power receiving means 81 configured as described above. The conductive wire 813 is disposed in a hole 423 formed in the axial direction at the center of the rotary spindle 42, and its tip is connected to a concave connector 814 (see FIG. 3) that fits the convex connector 64. ing. The power supply means 82 includes a stator side core 821 disposed on the outer peripheral side of the power reception means 81 and a power supply coil 822 disposed on the stator side core 821. The power supply coil 822 of the power supply means 82 configured as described above is supplied with high-frequency power via the electrical wiring 83.

  The power supply means 8 in the illustrated embodiment includes an AC power supply 84 of high frequency power supplied to the power supply coil 822 of the rotary transformer 80, a voltage adjustment means 85 as power adjustment means, and a high frequency power supplied to the power supply means 82. Frequency adjusting means 86 for adjusting the frequency of the power, control means 87 for controlling the voltage adjusting means 85 and the frequency adjusting means 86, and the frequency of ultrasonic vibration applied to the plurality of grinding wheels 52 are input to the control means 87. Input means 88 is provided. The power supply means 8 shown in FIG. 2 supplies AC power to the stator coil 72 of the electric motor 7 via the control circuit 89 and the electric wiring 821.

The spindle unit 4 in the illustrated embodiment is configured as described above, and the operation thereof will be described below.
When performing the grinding operation, AC power is supplied from the power supply means 8 to the stator coil 72 of the electric motor 7. As a result, the electric motor 7 rotates and the rotary spindle 42 rotates, and the grinding wheel 5 attached to the tip of the rotary spindle 42 is rotated.

  On the other hand, the power supply means 8 controls the voltage adjustment means 85 and the frequency conversion means 86 by the control means 87 to control the voltage of the high frequency power to a predetermined voltage (for example, 20V) and the frequency of the high frequency power to the predetermined frequency. (For example, in the case of the grinding wheel 5, it is converted to 40 kHz) and supplied to the power supply coil 822 of the power supply means 82 constituting the rotary transformer 80. When high-frequency power having a predetermined frequency is applied to the feeding coil 822 in this way, the power receiving coil 812 of the rotating power receiving means 81, the conductive wire 813, the concave connector 814, the convex connector 64, and the conductive wires 63a and 63b are used. High frequency power is applied to the pair of electrode plates 62a and 62b constituting the sonic vibration means 6. As a result, the ultrasonic transducer 61 is repeatedly displaced in the radial direction and the axial direction to vibrate ultrasonically. This ultrasonic vibration is transmitted to the plurality of grinding wheels 52 via the grinding wheel mounting portions 511a of the base body 511 constituting the wheel base 51, and the plurality of grinding wheels 52 are ultrasonically vibrated in the radial direction and the axial direction. . In the illustrated embodiment, a plurality of arc-shaped slits 511c are formed in the circumferential direction between the annular side wall 512 and the grindstone mounting portion 511a in the base body 511 constituting the wheel base 51. Transmission of ultrasonic vibration generated from the ultrasonic vibration means 6 to the wheel mount 43 via the annular side wall 512 is suppressed. Therefore, the ultrasonic vibration generated from the ultrasonic vibration means 6 is effectively transmitted to the plurality of grinding wheels 52 via the grinding wheel mounting portion 511a.

  Referring back to FIG. 1, the grinding apparatus in the illustrated embodiment moves the grinding unit 4 in the vertical direction (perpendicular to the holding surface of the chuck table described later) along the pair of guide rails 221 and 221. A grinding unit feed mechanism 10 that is moved in the direction). The grinding unit feed mechanism 10 includes a male screw rod 101 that is disposed on the front side of the upright wall 22 and extends substantially vertically. The male screw rod 101 is rotatably supported by bearing members 102 and 103 whose upper end and lower end are attached to the upright wall 22. The upper bearing member 102 is provided with a pulse motor 104 as a drive source for rotationally driving the male screw rod 101, and an output shaft of the pulse motor 104 is connected to the male screw rod 101 by transmission. A connecting portion (not shown) protruding rearward from the widthwise central portion is also formed on the rear surface of the movable base 31, and a through female screw hole (not shown) extending in the vertical direction is formed in this connecting portion. ) And the male screw rod 101 is screwed into the female screw hole. Accordingly, when the pulse motor 104 rotates in the forward direction, the moving base 31, that is, the grinding unit 3 is lowered or moved forward, and when the pulse motor 104 rotates in the reverse direction, the moving base 31, that is, the grinding unit 3 is raised or moved backward.

  Continuing the description with reference to FIG. 1, the chuck table mechanism 11 is disposed in the main portion 21 of the housing 2. The chuck table mechanism 11 includes a chuck table 12, a cover member 13 that covers the periphery of the chuck table 12, and bellows means 14 and 15 disposed in front of and behind the cover member 13. The chuck table 12 is configured to be rotated by a rotation driving unit (not shown), and is configured to suck and hold a wafer as a workpiece on its upper surface by operating a suction unit (not shown). Further, the chuck table 12 is moved between a workpiece placing area 24 shown in FIG. 1 and a grinding area 25 facing the grinding wheel 5 constituting the spindle unit 4 by a chuck table moving means (not shown). The bellows means 14 and 15 can be formed from any suitable material such as campus cloth. The front end of the bellows means 14 is fixed to the front wall of the main portion 21, and the rear end is fixed to the front end surface of the cover member 13. The front end of the bellows means 15 is fixed to the rear end surface of the cover member 13, and the rear end is fixed to the front surface of the upright wall 22 of the apparatus housing 2. When the chuck table 12 is moved in the direction indicated by the arrow 23a, the bellows means 14 is expanded and the bellows means 15 is contracted. When the chuck table 12 is moved in the direction indicated by the arrow 23b, the bellows means 14 is The bellows means 15 is expanded by contraction.

The grinding apparatus equipped with the grinding wheel in the illustrated embodiment is configured as described above, and the operation thereof will be described below.
When performing the grinding operation, a grinding wheel (for example, the grinding wheel 5 or the grinding wheel 50) having a natural frequency corresponding to ultrasonic vibration suitable for grinding an optical device wafer as a workpiece to be described later is wheel-mounted. Attach to 43. Then, as shown in FIG. 1, an optical device in which a gallium nitride compound semiconductor or the like is laminated on the surface of a sapphire substrate as a workpiece on a chuck table 12 positioned in a workpiece placement area 24 of a grinding apparatus. Place wafer W. A protective tape T is attached to the surface on which the device of the optical device wafer W is formed. The protective tape T side is placed on the chuck table 12. The optical device wafer W placed on the chuck table 12 in this manner is sucked and held on the chuck table 12 by suction means (not shown). If the optical device wafer W is sucked and held on the chuck table 12, the chuck table moving means (not shown) is operated to move the chuck table 12 in the direction indicated by the arrow 23a and position it in the grinding zone 25. Then, as shown in FIG. 7, the outer peripheral edges of the plurality of grinding wheels 52 of the grinding wheel 5 (50) are positioned so as to pass through the rotation center P of the chuck table 12, that is, the center of the optical device wafer W.

  If the optical device wafer W held on the grinding wheel 5 and the chuck table 12 is set in the positional relationship shown in FIG. 7, the chuck table 12 is rotated in the direction indicated by the arrow 12a in FIG. And the grinding wheel 5 is rotated in the direction indicated by the arrow 5a at a rotational speed of, for example, 6000 rpm. That is, by supplying AC power from the power supply means 8 to the stator coil 72 of the electric motor 7, the electric motor 7 rotates and the rotating spindle 42 rotates, and the grinding wheel attached to the tip of the rotating spindle 42. 5 is rotated. Then, the grinding wheel 5 is lowered to press the plurality of grinding wheels 52 against the back surface (surface to be ground), which is the top surface of the optical device wafer W, with a predetermined pressure. As a result, the surface to be ground of the optical device wafer W is ground over the entire surface.

  At the time of the grinding process described above, high-frequency power having a predetermined frequency suitable for the grinding wheel 5 (50) mounted on the wheel mount 43 is supplied to the power supply coil 822 of the power supply means 82 constituting the rotary transformer 80 by the power supply means 8. To do. As a result, a pair of electrode plates 62a constituting the annular ultrasonic vibration means 6 via the power receiving coil 812, the conductive wire 813, the concave connector 814, the convex connector 64, and the conductive wires 63a and 63b of the rotating power receiving means 81, High frequency power having a predetermined frequency is applied to 62b, and the annular ultrasonic vibration means 6 is ultrasonically displaced by being repeatedly displaced in the radial direction and the axial direction. This ultrasonic vibration is transmitted to the plurality of grinding wheels 52 via the grinding wheel mounting portions 511a of the base body 511 constituting the wheel base 51, and the plurality of grinding wheels 52 are ultrasonically vibrated in the radial direction and the axial direction. . When the plurality of grinding wheels 52 are ultrasonically vibrated in the radial direction and the axial direction in this way, grinding waste generated by grinding and staying between abrasive grains of the grinding wheel 52 and causing clogging acts on the grinding wheel 52. It is removed by flowing by slight vibration. Therefore, clogging of the grinding wheel 52 can be prevented and grinding can be performed efficiently.

2: device housing 3: grinding unit 31: moving base 4: spindle unit 41: spindle housing 42: rotating spindle 43: wheel mount 5, 50: grinding wheel 51: wheel base 52: grinding wheel 6: ultrasonic vibration means 61: Ultrasonic vibrators 62a, 62b: A pair of electrode plates 7: Electric motor 8: Power supply means 80: Rotary transformer 81: Power reception means 82: Power supply means 84: AC power supply 85: Voltage adjustment means 86: Frequency adjustment means 87 : Control means 88: Input means 10: Grinding unit feed mechanism 11: Chuck table mechanism 12: Chuck table

Claims (2)

A grinding wheel that is detachably mounted on a lower surface of a wheel mount that is provided at a lower end of a rotating spindle that constitutes a grinding means for grinding a workpiece held on a chuck table and includes a bolt insertion hole,
A wheel base, an annular grinding wheel mounted on the lower surface of the wheel base, and an annular ultrasonic vibration means disposed at a position corresponding to the inside of the annular grinding wheel on the wheel base Become
The wheel base is erected from a base body including a grindstone mounting portion for mounting the grinding wheel and an ultrasonic vibration means mounting portion for mounting the ultrasonic vibration means, and an outer peripheral portion of the base main body. An annular side wall formed from the upper end of the annular side wall, and an annular attachment portion formed inward from the upper end of the annular side wall.
A female screw hole is formed at a position corresponding to the bolt insertion hole provided in the wheel mount in the annular mounting portion.
A grinding wheel characterized by that. The grinding wheel according to claim 1, wherein a plurality of arc-shaped slits are formed in a circumferential direction between the annular side wall and the grindstone mounting portion in the base body of the wheel base.

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