JP2017213664A - Grind stone and grinding wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grind stone and grinding wheel capable of sufficiently discharging grinding swarf during grinding of a workpiece.SOLUTION: A grind stone 22 is configured by including two or more through-holes 25 penetrating from a grinding surface 220 to an opposite surface 220' on an opposite side. The grind stone has a mesh shape in which through-holes 25 each having a nearly columnar shape or a prismatic shape are aggregated, and a honeycomb structure formed of the through-holes each having a hexagonal column shape. Accordingly, the grind stone makes it possible to sufficiently feed a grinding fluid through the through-holes 25 to a working point at which the grind stone 22 comes into contract with a plate-like workpiece W, and possible to promote the discharge of the grinding swarf to effectively discharge the grinding swarf.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a grindstone for grinding a workpiece and a grinding wheel equipped with the grindstone.

  A workpiece such as a plate-shaped workpiece is thinned by being ground by, for example, a grinding device (for example, see Patent Document 1 below). The grinding apparatus includes a chuck table that holds a plate-like workpiece and a grinding wheel that includes a grindstone for grinding the plate-like workpiece. A communication path through which grinding water flows is formed inside the grinding wheel, and the communication path communicates with a supply port formed on the lower surface of the grinding wheel. In this grinding apparatus, by supplying grinding water from the supply port to the plate-like workpiece held by the chuck table via the communication path, the grinding workpiece generated by the grinding stone is discharged while grinding waste generated during grinding is discharged. It can be ground to a desired thickness.

JP 2013-086218 A

  However, in the conventional grinding wheel shown in Patent Document 1, when a plate-shaped workpiece is ground with a grindstone, a chuck table is formed from a supply port formed inside the grindstone that is annularly arranged and fixed to the lower portion of the grinding wheel. Grinding water can be supplied toward the plate-shaped workpiece held on the surface, but the grinding water does not flow to the processing point where the grindstone and the plate-shaped workpiece are in contact, and the grinding waste is sufficiently discharged. There is a problem that can not be.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to sufficiently discharge grinding waste during grinding of a workpiece.

  The present invention is a grindstone for grinding a workpiece, and includes two or more through holes penetrating from the grinding surface of the grindstone to the opposite surface, and is supplied with grinding water through the through holes. .

  The through hole may have a substantially cylindrical shape or a prismatic shape, and may have a mesh shape in which the through holes are gathered.

  The through hole has a hexagonal column shape, and may be formed of a honeycomb structure.

  You may comprise the said grinding surface of the said grindstone in polygonal shape.

  Further, the present invention is a grinding wheel for grinding a workpiece, and is disposed in a ring shape on an annular base having a wheel mount mounting surface to be mounted on the wheel mount, and on a free end of the annular base. In addition, the grinding water can be supplied from the annular base to the surface to be ground of the workpiece through the through hole.

  Since the grindstone according to the present invention includes two or more through-holes penetrating from the grinding surface of the grindstone to the opposite surface, the grinding water is distributed through the through-holes to the machining point where the grindstone and the workpiece are in contact with each other. It is possible to accelerate the discharge of the grinding waste and to sufficiently discharge the grinding waste.

  When the through hole has a substantially cylindrical shape or a prismatic shape and is configured with a mesh shape in which a plurality of through holes are gathered on the grinding surface of the grindstone, when the workpiece is ground with the grindstone, grinding is performed through the plurality of through holes. Since water can be supplied toward the processing point, it is possible to effectively promote the discharge of grinding scraps.

  When the through-hole has a hexagonal column shape and the grindstone is configured with a honeycomb structure in which a plurality of through-holes are aggregated, when grinding the workpiece with the grindstone, the grinding water is passed through the plurality of through-holes to the above processing point. Therefore, it is possible to more efficiently promote the discharge of grinding waste.

  When the grinding surface of the grindstone is configured in a polygonal shape, the workpiece can be accurately ground with the grindstone while supplying grinding water to the machining point through the plurality of through holes.

  The grinding wheel according to the present invention includes an annular base having a wheel mount mounting surface to be mounted on the wheel mount, and the above-described grindstone disposed in a ring shape at the free end of the annular base, Since the grinding water can be supplied from the base to the grinding surface of the workpiece through the through hole, the grinding water always flows efficiently toward the machining point through the through hole during grinding of the workpiece. Therefore, it is possible to prevent the grinding waste from being sufficiently discharged and the grinding waste from adhering to the grinding surface of the grindstone.

It is a perspective view which shows the structure of a grinding apparatus. It is a partially expanded sectional view which shows the state which grinds the plate-shaped workpiece | work hold | maintained at the chuck table by the 1st example of a grinding wheel. (A) is a perspective view which shows the structure of the 1st example of a grinding wheel. (B) is a perspective view showing a configuration of a rectangular parallelepiped shaped grindstone in which a prismatic through hole is formed. (C) is a bottom view showing a configuration of a rectangular parallelepiped shaped grindstone in which a prismatic through hole is formed. It is a perspective view which shows the structure of the rectangular parallelepiped-shaped grindstone in which the substantially cylindrical through-hole was formed. (A) is a perspective view which shows the structure of the 2nd example of a grinding wheel. (B) is a perspective view which shows the structure of the column-shaped grindstone in which the hexagonal column-shaped through-hole was formed. (C) is a bottom view showing a configuration of a cylindrical grindstone in which a hexagonal column-shaped through hole is formed. (A) is a perspective view which shows the structure of the 3rd example of a grinding wheel. (B) is a perspective view which shows the structure of the rectangular parallelepiped-shaped grindstone in which the hexagonal column-shaped through-hole was formed. (C) is a bottom view showing a configuration of a rectangular parallelepiped-shaped grindstone in which a hexagonal column-shaped through hole is formed. It is a bottom view which shows the structure of the grindstone which has a triangular-shaped grinding surface. It is a 4th example of a grinding wheel, Comprising: It is a partial expanded bottom view which shows the example of arrangement | positioning of the grindstone which has a triangular-shaped grinding surface in a free end part. It is a bottom view which shows the structure of the grindstone which has an egg-shaped grinding surface. It is a 5th example of a grinding wheel, Comprising: It is a partial expanded bottom view which shows the example of arrangement | positioning of the grindstone which has the egg-shaped grinding surface in a free end part. It is a bottom view which shows the structure of the grindstone which has a pentagonal grinding surface. It is a bottom view which shows the structure of the grindstone which has a step-shaped grinding surface. It is a bottom view which shows the structure of the grindstone in which the several through-hole from which a magnitude | size differs was formed.

  A grinding apparatus 1 shown in FIG. 1 has an apparatus base 2 extending in the Y-axis direction and a column 3 erected on the rear part of the apparatus base 2 in the Y-axis direction. On the upper surface of the apparatus base 2, a chuck table 4 having a holding surface 4a for sucking and holding a workpiece is disposed. The periphery of the chuck table 4 is covered with a cover 5. The chuck table 4 can reciprocate in the Y axis direction by a Y axis direction moving means (not shown).

  In front of the column 3 in the Y-axis direction, a grinding means 10 that grinds the workpiece, and a grinding feed means that moves the grinding means 10 up and down in a grinding feed direction (Z-axis direction) that approaches and separates from the chuck table 4. 30. The grinding feed means 30 includes a ball screw 31 extending in the Z-axis direction, a motor 32 connected to one end of the ball screw 31, a pair of guide rails 33 extending in parallel with the ball screw 31, and one surface being a grinding means. And an elevating plate 34 fixed to 10. The other surface of the elevating plate 34 is in sliding contact with the pair of guide rails 33, and a ball screw 31 is screwed into a nut formed inside the elevating plate 34. By rotating the ball screw 31 by the motor 32, the grinding means 10 can be lifted and lowered in the Z-axis direction together with the lifting plate 34.

  The grinding means 10 includes a spindle 11 having an axis in the Z-axis direction, a holder 13 that holds a spindle housing 12 that surrounds the outer periphery of the spindle 11, a motor 14 attached to one end of the spindle 11, and a lower end of the spindle 11. And a grinding wheel 20 mounted on the wheel mount 15 for grinding the workpiece. When the motor 14 rotates the spindle 11 at a predetermined rotation speed, the grinding wheel 20 can be rotated at a predetermined rotation speed.

  As shown in FIG. 2, the grinding wheel 20 is a first example of a grinding wheel, and includes an annular base 21 having a wheel mount attachment surface 210 attached to the wheel mount 15, and a free end portion of the annular base 21. 211 and a grindstone 22 arranged in a ring shape. When the grinding wheel 20 is mounted on the wheel mount 15, the bolt 16 is inserted into the screw hole formed in the wheel mount 15 with the lower surface of the wheel mount 15 in close contact with the wheel mount mounting surface 210 of the annular base 21. The grinding wheel 20 is mounted on the wheel mount 15 by inserting and fastening the bolt 16 with a screw hole formed in the annular base 21.

  As shown in the partially enlarged view of FIG. 2, the grindstone 22 includes two or more, preferably three or more through holes 25 penetrating from the grinding surface 220 for grinding the workpiece to the opposite surface 220 ′ on the opposite side. It has become. A ring-shaped recess 214 for fitting the grindstone 22 is formed at the free end 211 of the annular base 21. The grindstone 22 is fitted in the recess 214, and is bonded and fixed by an adhesive, for example.

  Inside the spindle 11, there is formed a flowing water passage 110 that penetrates the center of the spindle 11 and extends in the vertical direction, and a grinding water supply source 6 is connected to one end of the flowing water passage 110. A communication passage 150 connected to the other end of the flowing water passage 110 is formed inside the wheel mount 15. Further, inside the annular base 21, there are a grinding water supply hole 212 communicating with the communication passage 150, and supply channels 213 a and 213 b branched to the grinding water supply hole 212 by the inner member 215 of the annular base 21. And are formed. The supply channel 213 a communicates with the opposite surface 220 ′ of the grindstone 22, and the supply channel 213 b communicates with the side surface of the grindstone 22.

  Here, the grinding water supply hole 212 may be formed so that the end 215 a of the inner member 215 is positioned below the center of the grinding water supply hole 212. Accordingly, since the grinding water flowing downward from the grinding water supply hole 212 flows into the supply flow paths 213a and 213b, the grinding stone 22 and the workpiece are contacted from the supply flow path 213a through the through hole 25. The grinding water can be supplied, and the grinding water can be supplied toward the position close to the processing point (side surface side of the grindstone 22) through the supply channel 213b.

  In the grinding wheel 20, as shown in FIG. 3A, a plurality of grindstones 22 are arranged in a ring shape at equal intervals at the free end 211 of the annular base 21. If the interval between the adjacent grindstones 22 is too large, it is assumed that the grinding result of the workpiece (for example, the surface roughness of the workpiece) is adversely affected. Therefore, the material / size of the workpiece and the grindstone 22 are assumed. The interval between the adjacent grindstones 22 may be appropriately set according to the material or the like. Moreover, you may arrange | position the some grindstone 22 so that it may adjoin in the free end part 211. FIG. The number of grindstones 22 is not particularly limited.

  As shown in FIG. 3B, the grindstone 22 is formed in a rectangular parallelepiped shape, and the grinding surface 220 for grinding the workpiece has a quadrangular shape. The through holes 25 constituting the grindstone 22 are formed in a prismatic shape (a quadrangular prism in the illustrated example), and have a mesh shape in which a plurality of through holes 25 are gathered. As shown in FIG. 3C, the thickness H1 of the wall 23 of the adjacent through hole 25 is preferably at least 0.5 mm so that the strength of the grindstone 22 does not decrease. The size of the grindstone 22 is preferably composed of, for example, 2 to 3 inches. The number of through holes 25 is not limited to the number shown in the present embodiment, and may be increased or decreased according to the size of the grindstone 22 to be at least 2 or more. The grindstone 22 shown in this embodiment is formed of, for example, a porous member. Thereby, not only the plurality of through-holes 25 but also the entire grinding stone 22 can be distributed through all the porosities, and the grinding water can be supplied toward the above-described processing points.

  4 can be used instead of the grindstone 22 shown in FIG. The grindstone 22a shown in FIG. 4 is formed in a rectangular parallelepiped shape like the grindstone 22, and the grinding surface 220a for grinding the workpiece has a quadrangular shape. The through hole 26 constituting the grindstone 22a is formed in a substantially cylindrical shape, and has a mesh shape in which a plurality of through holes 26 are gathered. The number of the through holes 26 is not limited to the number shown in the present embodiment, and may be increased or decreased so as to be at least 2 according to the size of the grindstone 22a. Thus, since the grindstones 22 and 22a have a mesh shape in which a plurality of through holes 25 and 26 are gathered on the grinding surfaces 220 and 220a, when grinding the workpiece with the grindstones 22 and 22a, a plurality of grindstones 22 and 22a are provided. Grinding water can be efficiently supplied to the above-described processing points through the through holes 25 and 26, and discharge of grinding waste can be promoted.

  Next, an operation example of grinding the plate-like workpiece W shown in FIG. 2 using the grinding wheel 20 provided with the grindstone 22 in the grinding apparatus 1 shown in FIG. 1 will be described. The plate-like workpiece W is an example of a circular plate-like workpiece, and a tape T for protecting the device is attached to the surface Wa of the workpiece. On the other hand, the back surface Wb opposite to the front surface Wa is a surface to be ground that is ground by the grindstone 22.

  The front surface Wa side of the plate-like workpiece W is placed on the holding surface 4a of the chuck table 4, and the back surface Wb is exposed upward. Subsequently, a suction force of a suction source (not shown) is applied to the holding surface 4 a to suck and hold the plate-like workpiece W, and the chuck table 4 holding the plate-like workpiece W is moved below the grinding means 10. Subsequently, while the chuck table 4 is rotated in the direction of the arrow a, for example, and the grinding wheel 20 is rotated in the direction of the arrow a, for example, the grinding wheel 20 is held by the holding surface 4a of the chuck table 4 by the grinding feed means 30 shown in FIG. Lower in the direction approaching. Then, the grindstone 22 descending while rotating is brought into contact with the back surface Wb of the plate-like workpiece W for grinding.

  During the grinding of the plate-like workpiece W, the grinding water is continuously supplied from the grinding water supply source 6 toward the grindstone 22. Specifically, when the grinding water supply source 6 causes the grinding water to flow into the flow channel 110 inside the spindle 11, the grinding water flows from the grinding water supply hole 212 into the supply channels 213 a and 213 b through the communication path 150. The grinding water that has flowed into the supply flow path 213a passes through the plurality of through holes 25 from the opposite surface 220 ′ side of the grindstone 22, and is supplied to the processing point where the grindstone 22 and the back surface Wb of the plate-like workpiece W come into contact. . On the other hand, the grinding water that has flowed into the supply channel 213b is supplied to the side surface of the grindstone 22 through the supply channel 213b. During grinding of the plate-like workpiece W, the grinding water always flows efficiently toward the machining point, so that the grinding waste is sufficiently discharged and prevents the grinding waste from adhering to the grinding surface 220 of the grindstone 22. be able to. When the plate-like workpiece W reaches the desired thickness by proceeding with the grinding process in this way, the grinding means 10 is raised in a direction away from the holding surface 4a of the chuck table 4 to finish the grinding process. For example, pure water is used as the grinding water.

  A grinding wheel 20A shown in FIG. 5A is a second example of a grinding wheel, and a plurality of grindstones 22b are arranged in a ring shape at equal intervals at a free end 211a of the annular base 21a. . The free end portion 211a is a ring-shaped plane, and a plurality of grindstones 22b are bonded and fixed to the free end portion 211a with, for example, an adhesive. As shown in FIG.5 (b), the grindstone 22b is formed in the column shape, and the grinding surface 221 which grinds a workpiece has an elliptical shape. The grindstone 22b includes three or more through holes 27 penetrating from the grinding surface 221 to the opposite surface 221 'on the opposite side. The through hole 27 is formed in a hexagonal column shape, and the grindstone 22b has a honeycomb structure in which a plurality of through holes 27 are gathered. As shown in FIG. 5C, the thickness H2 of the wall 24 of the adjacent through hole 27 is preferably at least 0.5 mm so that the strength of the grindstone 22b does not decrease. As for the size of the grindstone 22b, for example, the major axis is preferably 2 to 3 inches. The number of the through holes 27 is not limited to the number shown in the present embodiment, and may be increased or decreased so as to be at least 2 or more according to the size of the grindstone 22b. Since the grindstone 22b is formed of, for example, a porous member, the grinding water can be distributed to the entire grindstone 22b not only through the plurality of through holes 27 but also through all the porosities, and grinding toward the above-described processing points is performed. It is possible to supply water.

  A grinding wheel 20B shown in FIG. 6A is a third example of a grinding wheel, and a plurality of grindstones 22c are arranged in a ring shape at a free end portion 211 of an annular base 21b. As shown in FIG. 6B, the grindstone 22c is formed in a rectangular parallelepiped shape, and the grinding surface 220c for grinding the workpiece has a quadrangular shape. The grindstone 22c includes the hexagonal column-shaped through hole 27 described above, and the grindstone 22c has a honeycomb structure in which a plurality of through holes 27 are gathered. As shown in FIG.6 (c), it is good to form thickness H3 of the wall 24a of the adjacent through-hole 27 to at least 0.5 mm so that the intensity | strength of the grindstone 22c may not fall. Thus, since the grindstones 22b and 22c are formed with hexagonal column-shaped through holes 27 and the entire grindstone has a honeycomb structure, when the workpiece is ground with the grindstones 22b and 22c, a plurality of through holes 27 are formed. Since it becomes possible to supply grinding water efficiently to the above-mentioned processing point through, discharge of grinding waste can be further promoted.

  The shape of the grinding surface of the grindstone that grinds the workpiece is not limited to a square shape or a circular shape as in the grindstones 22 to 22c described above. That is, the grinding surface of the grindstone may be formed in a polygonal shape other than a quadrangle, or may be formed in a non-circular shape. Below, the variation of the grinding surface of a grindstone is demonstrated, referring FIGS. 7-12.

  In the grindstone 22d shown in FIG. 7, a grinding surface 222 for grinding a workpiece is formed in a triangular shape. The grindstone 22d includes three or more hexagonal column-shaped through holes 27 penetrating from the grinding surface 222 to grind the workpiece to the opposite surface, and has a honeycomb structure. In the illustrated example, the grinding surface 222 of the grindstone 22d has an equilateral triangle shape, but is not limited to this shape, and may be a right triangle shape or an isosceles triangle shape. The grinding surface 222 of the grindstone 22d has three vertices A, B, and C, and is surrounded by three sides AB, BC, and AC formed by connecting adjacent vertices A, B, and C. For example, like the grinding wheel 20C shown in FIG. 8, the grindstone 22d has one of the three vertices A, B, and C of the grindstone 22d at the free end portion 211c of the annular base 21c (in the illustrated example). The vertex A) is directed to the inner peripheral edge 17 on the inner peripheral side of the grinding wheel 20C, and any one of the sides AB, BC, AC (the side BC in the illustrated example) is directed to the outer peripheral edge 18 on the outer peripheral side of the grinding wheel 20C. The apex B and the apex C may be arranged so as to face the circumferential direction of the grinding wheel 20C. Thereby, when the grinding wheel 20C is rotated and the workpiece is ground by the grindstone 22d, the area of the grindstone 22d that comes into contact with the portion where the grindstone 22d and the workpiece are frequently contacted (the central portion of the workpiece) is increased. The center portion of the workpiece is prevented from being excessively recessed as compared with the outer edge portion of the workpiece, and the grinding water can be supplied to the above-described processing points through the plurality of through holes 27. Can be further promoted. The three vertices A, B, and C of the grindstone 22d are preferably formed in an R shape.

  In the grindstone 22e shown in FIG. 9, a grinding surface 223 for grinding a workpiece is formed in an egg shape. That is, the outer shape of the grinding surface 223 is formed such that the side surfaces F1 and F2 swell from the end surface D thereof. The grindstone 22e includes three or more hexagonal column-shaped through holes 27 penetrating from the grinding surface 223 for grinding the workpiece to the opposite surface, and has a honeycomb structure. For example, like the grinding wheel 20D shown in FIG. 10, the grindstone 22e has a free end 211d of the annular base 21d with the end surface D of the grindstone 22e facing the inner edge 17 on the inner peripheral side of the grinding wheel 20D. It is good to arrange | position so that the side surfaces F1 and F2 of 22e may face the circumferential direction of the grinding wheel 20D. Thereby, since the area of the grindstone 22e which contacts the part (center part of a workpiece) with many times of contact with the grindstone 22e and a workpiece becomes small gradually, a nonuniformity generate | occur | produces in the to-be-ground surface of a workpiece. In addition, the grinding water can be supplied to the above-described processing points through the plurality of through holes 27, so that the discharge of the grinding waste can be promoted.

  In the grindstone 22f shown in FIG. 11, a grinding surface 224 for grinding a workpiece is formed in a pentagonal shape. The grindstone 22f includes three or more substantially cylindrical through holes 26 penetrating from the grinding surface 224 for grinding the workpiece to the opposite surface, and has a mesh shape. In the grindstone 22g shown in FIG. 12, the outer shape of the grinding surface 225 for grinding the workpiece is formed in a staircase shape. The grindstone 22g includes three or more prismatic through holes 25 penetrating from the grinding surface 225 for grinding the workpiece to the opposite surface, and is formed in a mesh shape. As described above, the grindstones 22f and 22g also have a mesh shape in which the plurality of through holes 26 and 25 are gathered on the grinding surfaces 224 and 225, so that the grinding water is supplied to the processing point through the plurality of through holes 26 and 25. It is possible to promote the discharge of grinding waste.

  The size of the above-described through holes 25, 26, and 27 is not limited to the configuration shown in the present embodiment. For example, the grindstone 22h shown in FIG. 13 includes three or more hexagonal column-shaped large through holes 28 penetrating from the rectangular grinding surface 220 to the opposite surface, and three or more penetrating from the grinding surface 220 to the opposite surface. And a small through hole 29 having a hexagonal column shape. In the grindstone 22h including the through holes having different sizes in this way, a large amount of grinding water can be supplied from the large through hole 28 to the above-described processing point, so that the processing quality of the workpiece is improved and the small through hole is provided. The presence of the holes 29 increases the contact area between the grinding surface 220 and the workpiece, so that the grinding efficiency is also improved. The sizes of the through holes 25, 26, 27, the large through hole 28, and the small through hole 29 are preferably set within a range of 3 to 10 mm. Note that the numbers of the large through holes 28 and the small through holes 29 are not limited to the numbers shown in the present embodiment, and may be increased or decreased so as to be at least 2 according to the size of the grindstone 22h.

  The grindstones 22 to 22h shown in the present embodiment are manufactured by, for example, extrusion molding. Specifically, for example, abrasive grains are kneaded into any one of vitrified bond, alumina, and resin bond, and the kneaded abrasive grains are pressed in a predetermined formwork, and then pressed at a predetermined temperature. The grindstone 22-22h can be manufactured by time sintering. In particular, when a vitrified bond or an alumina-based bond material is used, it is possible to obtain a highly accurate grindstone 22 to 22h. For example, a phenol resin, an epoxy resin, or a polyimide resin is used as the resin bond. Further, lubricity and heat dissipation may be improved by doping the abrasive grains with boron to produce the grindstones 22 to 22h. In addition, the kind of abrasive grain is not specifically limited.

1: Grinding device 2: Device base 3: Column 4: Chuck table 4a: Holding surface 5: Cover 6: Grinding water supply source 10: Grinding means 11: Spindle 110: Flow channel 12: Spindle housing 13: Holder 14: Motor 15 : Wheel mount 150: Communication path 16: Bolt 17: Inner edge 18: Outer edge 20, 20A, 20B, 20C, 20D: Grinding wheel 21: Ring base 210: Wheel mount mounting surface 211: Free end 212: Grinding water Supply holes 213a, 213b: Supply flow path 214: Recess 215: Inner member 215a: Ends 22, 22a, 22b, 22c, 22d, 22e, 22f, 22g, 22h: Grinding stones 220, 221, 222, 223, 224, 225 : Ground surfaces 23, 24: Walls 25, 26, 27: Through holes 28: Large through holes 29: Small through holes Hole 30: grinding feed means 31: ball screw 32: motor 33: Guide rail 34: elevating plate

Claims (5)

A grindstone for grinding a workpiece,
A grindstone including two or more through holes penetrating from the grinding surface of the grindstone to the opposite surface, and supplied with grinding water through the through holes.   The grindstone according to claim 1, wherein the through hole has a substantially cylindrical shape or a prismatic shape, and has a mesh shape in which the through holes are gathered.   The grindstone according to claim 1, wherein the through hole has a hexagonal column shape and has a honeycomb structure.   The grindstone according to any one of claims 1 to 3, wherein the grinding surface of the grindstone has a polygonal shape. A grinding wheel for grinding a workpiece,
An annular base having a wheel mount mounting surface to be mounted on the wheel mount;
The grindstone according to any one of claims 1 to 4, which is disposed in a ring shape at a free end of the annular base,
A grinding wheel for supplying grinding water from the annular base to the ground surface of the workpiece through the through hole.

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