JP2005297139A - Grinding wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding wheel having high grinding work capacity by projecting a work surface of a main grinding part from a surface of a grinding wheel body. <P>SOLUTION: This grinding wheel 10a has the grinding wheel body 20 and the main grinding part 30 integrally sintered to this grinding wheel body. The grinding wheel body 20 is formed by hardening a binding material 22 and an auxiliary abrasive grain 21 composed of diamond or molten alumina or silicon carbide. The main grinding part 30 is formed by being integrally hardened with the grinding wheel body 20 by a binding material 32 and a main abrasive grain 31 composed of a single body of any of diamond or CBN or a mixture of these or a mixture of the single body or the mixture and at least any of silicon carbide, mullite or molten alumina. The main grinding part 30 is formed higher in hardness than the grinding wheel body 20. The work surface 13 of the grinding wheel body 20 is abraded first in grinding work, and the work surface 13 of the main grinding part 30 projects from the surface of the grinding wheel body 20. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a grindstone used for grinding or polishing.

  A grindstone is a tool formed by solidifying hard particles, that is, abrasive grains with a binder, and fine pores are formed inside the grindstone. Processing using such a grindstone includes grinding processing and polishing processing. Rough processing is customarily referred to as grinding processing, and finishing processing is referred to as polishing processing. These processes are processes in which the grindstone is rotated and the work surface of the grindstone is pressed against the workpiece, that is, the work, and the work surface is scraped off as a large number of fine chips by abrasive grains, and is functionally synonymous. In the specification, both are referred to as grinding.

  There are two types of grindstones that grind the surface of the workpiece: cup type and disc type. The cup type is a grindstone that grinds with the end face of the grindstone as the machining surface. The disc type grinds with the end face of the grindstone as the machining surface. There are cases where the grinding is performed using the outer peripheral surface of the grindstone as a processing surface. As for the disk type grindstone, a type having a large thickness depending on the thickness is said to be straight, and a type having a small thickness is called a slicing blade or a dicing blade. In particular, some dicing blades have a thickness of 1 mm or less, for example, about 100 μm, and the outer peripheral surface is a processed surface. Is used to form kerfs.

  In such a grinding process, a grindstone in which abrasive grains and a binder are uniformly dispersed is generally used. When grinding is performed, chips removed from the surface of the workpiece are removed from the grindstone. The machining efficiency is lowered by cutting into the machining surface and clogging the machining surface. Therefore, it is necessary to perform an operation of periodically dressing the grindstone to remove the processed surface of the grindstone and to obtain a new cutting blade. In particular, when the pressing force of the grindstone against the workpiece is increased to increase the surface pressure applied to the abrasive grains, that is, the shared load, clogging becomes prominent, and the processing ability decreases.

  In order to make it difficult for the chips scraped from the workpiece surface to bite into the processing surface of the grindstone, attempts have been made to form kerfs or slits on the processing surface. However, if slits are formed in the grindstone, the strength of the grindstone will decrease. Therefore, there is a problem that the processed surface is easily worn, the grindstone needs to be frequently replaced, and a large number of slits cannot be formed.

  An object of the present invention is to provide a grindstone having a high grinding ability.

  Another object of the present invention is to provide a grindstone that can be continuously ground without performing a dressing operation.

  The grindstone of the present invention is a grindstone that has a processed surface and is rotationally driven by a rotating shaft, and is formed by sintering auxiliary abrasive grains for a base material and a binder, and main abrasive grains. And a bonding material, which extends in the wear direction of the work surface and is formed integrally with the grindstone main body at a predetermined interval in either or both of the rotation direction and the direction crossing it, and has a hardness higher than that of the grindstone main body. The grinding wheel main body is worn during grinding and the processing surface of the main grinding portion protrudes from the surface of the grinding wheel body.

  The grindstone of the present invention is characterized in that the main abrasive has a higher hardness than the auxiliary abrasive. In the grindstone of the present invention, the main abrasive grains may be any one of diamond and CBN or a mixture thereof, or a mixture of the single or the mixture and at least one of silicon carbide, mullite, or molten alumina. The auxiliary abrasive grains are diamond, molten alumina, or silicon carbide as a single substance or a mixture. Further, in the grindstone of the present invention, the main abrasive grains of the main grinding part contain either a single body of diamond and CBN or a mixture thereof in a volume ratio of 10 to 100%, and include the binder. The main grinding part contains either diamond or CBN alone or a mixture thereof in a volume ratio of 5 to 65%, and the bond strength of the main grinding part is higher than that of the grindstone body. Furthermore, the grindstone of the present invention is characterized in that the binding material of the main grinding part is vitrified bond.

  In the grindstone of the present invention, the grindstone main body is a disk type having a machining surface on the outer peripheral surface, the main grinding portion on the machining surface is projected from the machining surface of the grindstone main body along the axial direction, and the main grinding portion is It is formed by extending in the radial direction of the grindstone body, or formed by extending in the radial direction and inclining in the circumferential direction.

  The grindstone of the present invention is a cup-type or disk-type having a grindstone body with a machining surface at an end surface, and the main grinding portion on the machining surface is formed by extending in the radial direction of the grindstone body, or extending in the radial direction; It is formed by being inclined in the circumferential direction. In the grindstone of the present invention, the grindstone body has a cup shape or a disk shape having a machining surface at an end surface, and the main grinding portion on the machining surface has a large number of honeycomb-shaped patterns, square patterns, rhombus patterns, or triangular patterns. It is characterized by that.

  In the present invention, the grindstone includes a grindstone main body formed by solidifying the auxiliary abrasive grains and the binder, and a main grinding portion formed by solidifying the main abrasive grains and the binder and having a higher hardness than the grindstone main body. Therefore, the processing surface of the grindstone body is worn first, that is, preferentially worn during grinding. Therefore, the processing surface of the main grinding part protrudes from the surface of the grindstone main body, so that the grinding process is mainly performed by the edge of the main grinding part, and the grindstone main body achieves the function of maintaining the grindstone shape and increasing the strength. To do. Thereby, the surface pressure applied to the main grinding part, that is, the shared load applied to the main abrasive grains can be increased, and the grinding efficiency can be increased. Since the main grinding part is prevented from biting into the main grinding part during grinding, grinding can be performed continuously without frequent dressing.

  The amount of wear of the grindstone body is increased so that the grindstone body wears before the main grinding portion during grinding, and as one method for that purpose, the main abrasive grains of the main grinding portion are, for example, diamond or CBN. Even if the same kind of bonding material is used by making the types of both abrasive grains different from each other, for example, silicon carbide, mullite or molten alumina alone or a mixture thereof, the grinding stone body The amount of wear can be made larger than that of the main grinding part. Further, as another method, the abrasive strength of the grindstone body is made larger than that of the main grinding portion by adjusting the bonding strength by making the type of abrasive grains different or by making one or both of the types or amounts of the binders different. be able to. You may make it use the same kind of abrasive grain by the main grinding part and a grindstone main body, and make the kind of binder differ. When the same kind of abrasive grains is used, the hardness of the main grinding portion can be made higher than that of the grindstone main body by making the grain size of the main abrasive grains larger than that of the auxiliary abrasive grains.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 to 3 are perspective views showing a grindstone according to an embodiment of the present invention. A grindstone 10a shown in FIG. 1 is a disk type, and flanges 11 are fixed to both surfaces, and the flange 11 is attached to the rotary shaft 12. This grindstone 10a has a processing surface 13 on the outer peripheral surface, and is used to form a grid-like cut groove on a semiconductor wafer or substrate as a workpiece. The grindstone 10a is set to a thickness of 1 mm or less, and is also referred to as a slicing blade, a dicing blade, or a dicing saw.

  The grindstone 10b shown in FIG. 2 is a disk type like the grindstone 10a, and the outer peripheral surface is the processing surface 13, but the thickness of the grindstone 10a is set larger than the grindstone 10a shown in FIG. Used to grind the plane of the workpiece. When grinding the flat surface of the workpiece with the end face of this type of grindstone 10b as the machining surface, the radial dimension of the end face is set larger than that shown in FIG.

  A grindstone 10c shown in FIG. 3 is a cup type, and is used for grinding a flat surface of a workpiece with an end surface as a machining surface 13. The grindstone 10 c is attached to a holder 14 fixed to the rotary shaft 12, and is driven to rotate by the rotary shaft 12 via the holder 14. By surface grinding using the grindstones 10b and 10c shown in FIGS. 2 and 3, for example, the surface of the wafer can be mirror-finished before the pattern of the semiconductor integrated circuit is formed on the semiconductor wafer.

  4A is an enlarged view of the grindstone 10a shown in FIG. 1. The grindstone 10a has a disk shape with an outer diameter of about 60 mm, an inner diameter of about 40 mm, and a thickness of about 100 μm. Therefore, the machined surface 13 is worn so that the outer diameter decreases with grinding. The inner and outer dimensions and thickness of the grindstone 10a can be arbitrarily set in accordance with the workpiece W, and can be set to about several tens of μm to 50 μm, for example.

  The grindstone 10a has a grindstone main body 20 and a main grinding portion 30 formed by solidifying the grindstone main body 20 by sintering. The main grinding portion 30 is 12 at predetermined intervals in the rotation direction, that is, every 30 degrees. It is provided in several places, each layered. Each of the main grinding portions 30 that are layered and become the main grinding layer extends in the radial direction that is the wear direction of the grindstone 10a, and is exposed on both side surfaces and the outer peripheral surface (working surface) 13 of the grindstone main body 20, The portion exposed on the surface 13 extends in the axial direction in the form of a line or strip. The length of the main grinding portion 30 in the radial direction is about 5 mm, and the grindstone 10a can be used until the main grinding portion 30 is almost worn, that is, until the outer diameter is worn to about 50 mm.

4B is a partially enlarged cross-sectional view of the grindstone 10a of FIG. 4A, and the grindstone main body 20 is formed of auxiliary abrasive grains 21 for a base material and a binder 22 that connects the abrasive grains together. The inside is porous with fine pores 23 formed therein. The main grinding part 30 is formed of a main abrasive grain 31 having a hardness higher than that of the auxiliary abrasive grains 21 and a binder 32 for connecting the abrasive grains, and has a porous structure in which fine pores 33 are formed. , Each is integrally formed by hardening. As the auxiliary abrasive grains 21, silicon carbide SiC, that is, GC, mullite (3Al ₂ O ₃ -2SiO ₂ ), or molten alumina Al ₂ O _3, that is, a simple substance of WA or a mixture thereof can be used. The diameter is 0.1 to 300 μm. On the other hand, as the main abrasive grains 31, diamond having a hardness higher than that of fused alumina, silicon carbide, or mullite, that is, diamond abrasive grains, is used, and the average particle diameter is 0.1 to 300 μm. However, instead of diamond, cubic boron nitride (CBN) abrasive grains, that is, CBN may be used, or a mixture of diamond and CBN may be used. On the other hand, vitrified bonds are used as the bonding material 22 of the grindstone main body 20 and the bonding material 32 of the main grinding part 30, but as the respective bonding materials 22 and 32, in addition to vitrified bonds, resinoid bonds, metal bonds, and electric bonds are used. Various bond materials such as adhesion bond can be used.

  Thus, the grindstone main body 20 is formed by the auxiliary abrasive grains 21 for the base material made of molten alumina, mullite, or silicon carbide, and the main grinding portion 30 is formed by using diamond having higher hardness as the main abrasive grains 31. Therefore, when grinding is performed using the grindstone 10a shown in FIG. 1, the work surface of the grindstone main body 20 is worn out before the work surface of the main grinding portion 30, as shown in FIG. In addition, the processing surface of the main grinding portion 30 is protruded by about 10 μm from the processing surface of the grindstone main body 20, and grinding is performed by the edge 34. The edge 34 is created along with the grinding process. However, the auxiliary abrasive grain 21 may contain diamond.

  If the grindstone main body 20 is worn earlier than the main grinding portion 30, that is, if the amount of wear of the grindstone main body 20 is larger than that of the main grinding portion 30, the main grind that constitutes the grindstone main body 20 and the main grinding portion 30. The types and amounts of the grains 31 and the binder 32 and the auxiliary abrasive grains 21 and the binder 22 constituting the grindstone main body 20 are not limited to those described above. For example, the main abrasive grains 31 and the auxiliary abrasive grains 21 may be the same type of abrasive grains, and the respective binding materials 32 and 22 may be made different. Further, the main abrasive grains 31 and the auxiliary abrasive grains 21 may be the same type, and the particle diameter of the main abrasive grains 31 may be made larger than the particle diameter of the auxiliary abrasive grains 21, in which case the respective binders are used. 32 and 22 may be the same type or different types. That is, in order to realize that the grindstone main body 20 is worn before the main grinding portion 30, that is, the amount of wear of the grindstone main body 20 is larger than that of the main grinding portion 30, first, the main abrasive grains 31 and the auxiliary abrasive grains 21. An optimum grinding wheel can be obtained by one of or a combination of the method of adjusting the type, size, and amount of the second and the method of appropriately setting the type, amount, and the like of each of the binding materials 22 and 32. .

  Thus, it is sufficient that the hardness of the main grinding part 30 is higher than that of the grindstone main body 20, that is, it is set so as not to be worn easily. As the main grinding part 30, any one of diamond and CBN or a mixture thereof, or A single substance or a mixture thereof and at least one of silicon carbide, mullite, and molten alumina can be used. In the case of using a single body of diamond and CBN or a mixture of these and other abrasive grains, it contains a single body of diamond and CBN or a mixture thereof in a volume ratio of 10 to 100%, and a binder It is preferable that the main grinding part 30 including 32 contains diamond and CBN alone or a mixture thereof in a volume ratio of 5 to 65%.

  FIG. 5 is a view showing a state in which the groove G is machined in the workpiece W by the grindstone 10a shown in FIG. 1. When grinding is performed using the grindstone 10a, the surface of the workpiece W has the grindstone body 20 on the surface. An outer peripheral surface and the processing surface of the main grinding part 30 whose hardness is higher than this will contact repeatedly. Thereby, as above-mentioned, the processing surface of the grindstone main body 20 will be worn out before the processing surface of the main grinding part 30, and the auxiliary abrasive grain 21 missing from the grindstone main body 20 during grinding is missing. It enters between the main grinding part 30 and the workpiece W and functions as a kind of loose abrasive grains. Thus, since the missing auxiliary abrasive grains 21 function as a kind of loose abrasive grains, the processed surface of the main grinding portion 30 protrudes from the processed surface of the grindstone body 20, that is, a dressed state. Therefore, good grinding surface quality can be obtained without leaving deep indentations on the workpiece W while maintaining the grinding ability for the workpiece W due to the dressing effect. Further, the work surface of the workpiece W is mainly ground by the work surface of the main grinding part 30 and is supplementarily ground by the work surface of the grindstone main body 20, and the auxiliary work surface is the main grinding part. Since it is worn out earlier than the processing surface 30, the cutting edge 34 of the processing surface 13 of the main grinding portion 30 is always kept exposed.

  And since the main grinding part 30 in the process surface 13 will be in the state protruded rather than the grindstone main body 20, a big shared load is added to the main abrasive grain 31 in the main grinding part 30 with the pressing force added to the workpiece | work W by a grindstone. Thus, the surface pressure applied to the main abrasive grains 31 is increased. Thereby, the function which scrapes off the surface of the workpiece | work W with the main abrasive grain 31 increases, and processing efficiency improves. This can be achieved even if the pressing force of the grindstone 10a against the workpiece W is made larger than before and the surface pressure applied to the abrasive grains 21 and 31 is increased, and the grinding efficiency can be increased.

  6 (A) to 6 (E) are front views showing modifications of the pattern of the main grinding part 30 provided on the grindstone 10a, respectively. The grindstone shown in FIG. 6 (A) is a circle of the main grinding part 30. The pitch in the circumferential direction is smaller than that of the grindstone shown in FIGS. 1 and 4, and 18 main grinding portions 30 are provided every 20 degrees in the circumferential direction. The grindstone shown in FIG. 6 (B) is provided with 24 main grinding portions 30 every 15 degrees in the circumferential direction, and the grindstone shown in FIG. 6 (C) is main ground every 10 degrees in the circumferential direction. 36 portions 30 are provided. The grindstone shown in FIG. 6D is formed with the main grinding portion 30 extending in the radial direction and inclined in the circumferential direction. In the grindstone shown in FIG. 6 (E), the main grinding part 30 is formed in a dot shape, and each main grinding part 30 is formed continuously in the axial direction so as to be exposed at both end faces of the grindstone. . As described above, the pattern of the main grinding portion 30 including the pitch in the circumferential direction of the main grinding portion 30, the thickness in the circumferential direction, and the dimension in the wear direction of the grindstone is arbitrarily set according to the type of the workpiece W and the like. can do.

  The area of the main grinding part 30 occupied by the processing surface 13 of the grindstone 10a can be arbitrarily changed by changing the width dimension in the rotation direction of the layered main grinding part 30. % Or less can be set.

  Also for the grinding wheel 10b for surface grinding shown in FIG. 2, the pattern of the end face is not limited to the pattern shown in FIG. 2, but may be as shown in FIGS. 6 (A) to 6 (E). In the grindstone 10b, since the outer peripheral surface is the processed surface 13, the axial length of the processed surface 13 is set to be longer than that of the grindstone 10a shown in FIG. 1, and the main grinding portion 30 is linear or strip-shaped on the outer peripheral surface. Become longer. The axial length of the processed surface 13 can be set to about 50 to 100 mm, for example.

  The grindstone 10c shown in FIG. 3 is also a grindstone for surface grinding. In this case, the flat end surface of the grindstone 10c serves as the processing surface 13. Since this type of grindstone 10c wears in the direction in which the thickness of the grindstone 10c decreases with grinding, that is, in the axial direction of the rotary shaft 12, the main grinding layer, that is, the main grinding portion 30 extends in the thickness direction of the grindstone main body 20. In addition to being formed, a main grinding portion 30 extends in the radial direction on the processed surface 13. Since this type of grindstone 10c is in contact with the work surface of the workpiece W, the main grinding portion 30 is provided from the outer peripheral edge to the inner peripheral edge of the end surface.

  FIGS. 7A to 7F are front views showing variations of the pattern of the main grinding portion 30 formed on the grindstone 10c, respectively, and FIGS. 7C to 7F show the grindstone 10c. Only a quarter portion of is shown on an enlarged scale. The grindstone shown in FIG. 7 (A) has a larger number of main grinding portions 30 with a smaller pitch in the circumferential direction than the grindstone shown in FIG. 3, and the grindstone shown in FIG. 7 (B) The main grinding portion 30 extends in the radial direction and is inclined in the circumferential direction. Further, in the grindstone shown in FIG. 7C, the main grinding portion 30 on the processed surface 13 has a honeycomb shape and is exposed to the grindstone main body 20.

  Further, the grindstone shown in FIG. 7D has a portion 30a in which the layered main grinding portion 30 on the processing surface 13 extends in parallel with each other in the first direction, and a second direction perpendicular to the portion 30a. The main grinding part 30 in the processing surface 13 is formed in many square patterns. In the grindstone shown in FIG. 7E, the layered main grinding portion 30 on the processing surface 13 extends in parallel with each other in the first and second directions in the same manner as in the case shown in FIG. 7D. , 30b, but the portion in the first direction is inclined with respect to the portion in the second direction, and the main grinding portion 30 in the processed surface 13 is formed in a number of rhombus patterns. . Further, in the grindstone shown in FIG. 7 (F), in addition to the portions 30a and 30b in the two directions shown in FIG. 7 (E), the main grinding portion 30 is a portion 30c extending in parallel with each other in the third direction. The main grinding part 30 is formed in a number of triangular patterns.

  7A to 7F, the pattern of the main grinding portion 30 on the processing surface 13 of the grindstone 10c is shown, but the main grinding portion 30 is layered in the thickness direction of the grindstone 10c, that is, the wear direction of the grindstone. It extends. The pattern of the main grinding portion 30 shown in FIG. 7 is a disc-type grindstone as shown in FIG. 2 and can also be applied to a grindstone having an end surface as the machining surface 13. Also in the grindstone shown in FIGS. 7A to 7F, the area indicated by the main grinding portion 30 shown on the processed surface 13 can be set to 10% or less of the total processed surface 13.

  8 and 9 are perspective views showing a grindstone according to still another embodiment of the present invention. The grindstone 10d shown in FIG. 8 is a disk type, and the outer peripheral surface is a machining surface 13. FIG. The grindstone 10d has a disc-shaped two-layer grindstone main body 20 and a disc-shaped main grinding portion 30 sandwiched between them, and these are integrally formed. The wheel 13 is integrally formed with the grindstone main body 20 at a predetermined interval in the direction of wear of the surface 13 and across the rotational direction, that is, in the thickness direction of the grindstone 10d.

  On the other hand, the grindstone 10e shown in FIG. 9 is a modification of FIG. 8, and the main grinding part 30 extends in the wear direction of the processed surface 13, and has a predetermined interval in the thickness direction of the grindstone 10e as in FIG. And is integrally formed with the grindstone main body 20 at a predetermined interval in the rotation direction of the grindstone 10e as in the case shown in FIGS. Also in the case of the grindstones 10 d and 10 e shown in FIGS. 8 and 9, the main grinding part 30 has higher hardness than the grindstone main body 20.

  In the grindstones 10a to 10e of the present invention, the grindstone main body 20 and the main grinding part 30 are integrally sintered, and the grindstone main body 20 and the material of the main grinding part 30 integrated with the grindstone main body 20 are bundled together in the step before sintering. It will be molded. In order to form the main grinding portion 30 and the grindstone main body 20 into an integrated shape, the slurry for the grindstone main body and the slurry for the main grinding portion in which the liquid is mixed with the abrasive grains and the binder are layered, respectively. Laminate. When the grindstone formed in this manner is integrally sintered in a firing furnace, a grindstone as shown in the figure can be manufactured.

  In the illustrated grindstones 10a to 10e, the main abrasive grains 31 of the main grinding portion 30 are diamond, but CBN may be used, or a mixture of diamond and CBN may be used, or a single substance of diamond and CBN or a mixture thereof. It may be a mixture of the body and silicon carbide or molten alumina. Similarly, although the auxiliary abrasive grains 21 of the grindstone body 20 are silicon carbide, mullite, or molten alumina, a mixture thereof may be used.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, although the illustrated grindstone is for grinding a workpiece made of a hard and brittle material such as a semiconductor wafer, sapphire, silicon carbide, etc., the grindstone of the present invention can also be used for grinding a metal workpiece. Can be used. When grinding metal workpieces, it is possible to use fused alumina or silicon carbide as the main abrasive grains, and use abrasive grains with a lower hardness than the auxiliary abrasive grains without using a grindstone with diamond as the main abrasive grains. The grindstone which was made can be used. Further, regarding the binding material, various materials can be selected in accordance with the grindstone body 20 and the main grinding portion 30.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a thin disc-type grindstone as an embodiment of the present invention. It is a perspective view which shows a disk-type grindstone with a large thickness as other embodiment of this invention. It is a perspective view which shows a cup-type grindstone as other embodiment of this invention. (A) is an enlarged view of the grindstone shown in FIG. 1, (B) is a partially expanded sectional view of the grindstone shown in FIG. 4 (A). (A) is a front view which shows the state which is processing the groove | channel on the workpiece | work with the grindstone shown in FIG. 1, (B) is sectional drawing of FIG. 5 (A). (A)-(E) are front views which show the modification of the main grinding part pattern formed in a grindstone, respectively. (A)-(E) are front views which show the modification of the main grinding part pattern formed in a grindstone, respectively. It is a perspective view which shows the disk type grindstone as further another embodiment of this invention. It is a perspective view which shows the disk type grindstone which is a modification of FIG.

Explanation of symbols

10a to 10e Whetstone 11 Flange 12 Rotating shaft 13 Work surface 14 Holder 20 Whetstone main body 21 Auxiliary abrasive grain 22 Binder 23 Pore 30 Main grinding part 31 Main abrasive grain 32 Binder 33 Pore 34 Edge W Workpiece

Claims (8)

A grindstone having a processing surface and driven to rotate by a rotating shaft,
A grindstone body formed by solidifying auxiliary abrasive grains for a base material and a binder,
The grindstone main body is formed of a main abrasive grain and a binder, and is formed integrally with the grindstone main body at a predetermined interval in the rotation direction and / or in a direction crossing the rotation direction. A main grinding part having a higher hardness than
A grindstone characterized in that a grinding surface of the grindstone body is worn during grinding and the machining surface of the main grinding portion protrudes from the surface of the grindstone body.   The grindstone according to claim 1, wherein the main abrasive has a higher hardness than the auxiliary abrasive.   3. The grindstone according to claim 1, wherein the main abrasive grains are any one of diamond and CBN or a mixture thereof, or the single or the mixture and at least one of silicon carbide, mullite, and molten alumina. A grindstone characterized in that it is a mixture, and the auxiliary abrasive grains are a simple substance or a mixture of diamond, fused alumina or silicon carbide.   The grindstone according to claim 3, wherein the main abrasive grains of the main grinding portion contain a simple substance of diamond and CBN or a mixture thereof in a volume ratio of 10 to 100%, and include the binder. The grindstone is characterized in that the main grinding portion contains any one of diamond and CBN or a mixture thereof in a volume ratio of 5 to 65%, and the bond strength of the main grinding portion is higher than that of the grindstone body.   The grindstone according to any one of claims 1 to 4, wherein the binding material of the main grinding portion is a vitrified bond.   The grindstone according to any one of claims 1 to 5, wherein the grindstone main body is a disk type having a machining surface on an outer peripheral surface, and the main grinding portion on the machining surface extends along the axial direction from the machining surface of the grindstone main body. A grindstone characterized in that it is projected and formed by extending the main grinding portion in the radial direction of the grindstone main body, or extending in the radial direction and inclined in the circumferential direction.   The grindstone according to any one of claims 1 to 5, wherein the grindstone main body is a cup shape or a disk shape having a work surface on an end surface, and the main grinding portion on the work surface is extended in a radial direction of the grindstone main body. A grindstone characterized by being formed or extending in the radial direction and inclined in the circumferential direction. The grindstone according to any one of claims 1 to 5, wherein the grindstone main body is a cup shape or a disk shape having a work surface at an end face, and the main grinding portion on the work surface is a large number of honeycomb-shaped patterns, square patterns, A whetstone characterized by a rhombus pattern or a triangular pattern.

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