JP2016203337A - Grindstone and manufacturing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grindstone having long lifetime, which comprises, between abrasive grains, a member for adjusting intervals between the abrasive grains, and a manufacturing method for the same.SOLUTION: A grindstone 10 comprises: a plurality of super-abrasive grains 12 (abrasive grains) which are arranged so as not to contact each other; a vitrified bond 14 (a bonding agent) which is formed in a bridge shape to bridge the plurality of super-abrasive grains 12 (abrasive grains) with each other and bonds the plurality of super-abrasive grains 12 (the abrasive grains) with each other; a plurality of fine particles 16 which are arranged in an assembly state in the vitrified bond 14 and interposed between the plurality of super-abrasive grains 12 so as to arrange the plurality of super-abrasive grains 12 in a non-contact manner; and gas cavities 18 which are formed around the vitrified bond 14.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a grindstone and a manufacturing method thereof.

  Conventionally, in grinding processing with high efficiency, in order to prevent thermal damage such as grinding burn and grinding crack and to obtain better processing accuracy, processing is performed with a grindstone having low grinding resistance. In this case, in order to reduce the grinding resistance, it is effective to use a low-concentration grindstone having a low abrasive content (unit concentration) per unit volume. Usually, the low-concentration grindstone is formed by mixing abrasive grains, an aggregate disposed between the abrasive grains, and a binder, and then sintering. At this time, for example, WA (white alumina) is often used as the aggregate disposed between the abrasive grains. However, in WA or the like, when grinding of a workpiece with a grindstone progresses, wear of the aggregate progresses due to chips discharged from the workpiece, and the surface on the workpiece side is flattened to form a smooth portion. . This smooth portion increases the grinding resistance. Then, the aggregate may be largely crushed or dropped due to this increase in grinding resistance. For this reason, for example, the binder, which is a bond bridge, is destroyed, and as a result, the CBN abrasive grains fall off and the tool life may be reduced.

Japanese Patent No. 5398132

  In order to solve the above-described problems, there is a conventional technique disclosed in Patent Document 1. In the technique of Patent Document 1, the aggregate is composed of porous ceramics having many fine holes. As a result, the grinding of the workpiece proceeds with the grindstone, the wear of the aggregate progresses, and even when the destruction of the aggregate starts, the destruction remains between the fine holes formed inside, so that the porous Aggregate is repeatedly broken down to fine holes, and is prevented from being crushed at once. However, it is very difficult to control the arrangement of the pores inside the porous ceramic. For this reason, after destruction begins, there is no guarantee that the destruction can be kept small.

  This invention is made | formed in view of such a situation, providing the grindstone with a long life, and its manufacturing method, providing the member which adjusts the space | interval between abrasive grains between abrasive grains. Objective.

  In order to solve the above-mentioned problem, the grindstone according to claim 1 of the present invention is formed in a bridge shape that bridges each of the plurality of abrasive grains and the plurality of abrasive grains arranged in non-contact with each other. And a plurality of fine particles arranged in a state of being aggregated in the binder and arranged in a non-contact manner by interposing between the plurality of abrasive grains. And pores formed around the binder.

  Thus, in the binder which bridge | crosslinks and couple | bonds each abrasive grain in bridge shape, it has arrange | positioned in the state which the several fine particle aggregated. For this reason, even if grinding of a workpiece progresses with a grindstone and the bridging portion of the binder is worn away by chips discharged from the workpiece, a plurality of fine particles can be detached in units of fine particles. As a result, since the plurality of fine particles are not greatly broken as a lump at once, the cross-linked portion of the binder containing the plurality of fine particles is also destroyed and detached in a large amount at one time to impair the bonding force between the abrasive grains. There is no risk of the abrasive grains falling off. Thereby, the lifetime of a grindstone can be improved.

  According to the method for producing a grindstone of claim 6 according to the present invention, the grindstone is formed in a bridge shape that bridges each of the plurality of abrasive grains arranged in non-contact with each other and the plurality of abrasive grains, A plurality of binders that bind each of the plurality of abrasive grains and a plurality of abrasive grains that are arranged in a state of being gathered in the binder and that are arranged between the plurality of abrasive grains so that the plurality of abrasive grains are arranged in a non-contact manner. A granulation step of forming a plurality of granulated powders by adhering the plurality of fine particles to each other by an adhesive member and granulating the fine particles; and pores formed around the binder; and The plurality of granulated powders and the plurality of abrasive grains before the formation of the grindstone are mixed with the binder in a powder state, and the plurality of granulated powders are respectively arranged between the adjacent abrasive grains. A mixing step for forming a molded body, and the intermediate molded body is put into a mold, Pressing the inside of the mold to form a pressure-molded body, and heating the pressure-molded body causes a part or all of the adhesive members forming the granulated powder to disappear and the plurality An adhesive member space is formed between the fine particles, and the molten binder is allowed to flow into the adhesive member space and a space other than the adhesive member space between the plurality of fine particles, and from the granulated powder to the adhesive member A heating step of including the plurality of fine particles in the aggregated state formed by erasing a part or all of the inside thereof and cross-linking between the adjacent abrasive grains. Thereby, the grindstone similar to the grindstone of Claim 1 can be manufactured.

1 is an overall view of a grindstone showing an embodiment of the present invention. It is the elements on larger scale which show the structure | tissue of the grindstone surface vicinity of a grindstone layer. FIG. 3 is a detailed diagram illustrating a relationship between abrasive grains and a plurality of fine particles in FIG. 2. It is a flowchart of the manufacturing method of a grindstone layer. It is the elements on larger scale for demonstrating granulated powder. It is the elements on larger scale for demonstrating an intermediate molded object. It is a partial enlarged view for demonstrating a press-molding body. It is a figure explaining the mode of omission of particulates at the time of grinding.

(1. Overall configuration of the grinding wheel 10)
As shown in FIG. 1, the grindstone 10 is a grinding wheel formed in a disk shape. The grindstone 10 includes a disk-shaped core 21 and a ring-shaped grindstone layer 22. The core 21 is formed of a metal material such as steel, aluminum, or titanium, or an FRP (fiber reinforced plastic) material, ceramics, or the like. The grindstone layer 22 is fired into a ring shape, and is fixed to the outer periphery of the core 21 by an adhesive or sintering. Alternatively, the grindstone layer 22 may be formed such that a plurality of grindstone segments are bonded to the outer periphery of the core 21 to form a ring shape.

  A center hole 23 is formed through the center of the core 21. The center hole 23 is fitted into a centering boss that protrudes from the shaft end of a grinding wheel shaft provided in a grinding wheel base (not shown). A plurality of bolt holes 24 (four in this embodiment) are formed around the center hole 23. Bolts that are screwed into screw holes that open to the shaft end of the grindstone shaft are inserted into the plurality of bolt holes 24. The grindstone 10 is fixed to the grindstone shaft by inserting bolts into the bolt holes 24 and screwing the bolts into the screw holes.

(2. Configuration of the grinding wheel layer 22)
As shown in the partially enlarged view of FIG. 2, the grindstone layer 22 includes abrasive grains 12 (described as superabrasive grains 12 of diamond or CBN in this embodiment) and a binder 14 (in this embodiment, vitrified bond). 14), a plurality of fine particles 16 disposed inside the binder 14, and pores 18.

  As described above, the superabrasive grains 12 (abrasive grains) are formed from, for example, CBN (cubic boron nitride) abrasive grains or diamond grains. In the present embodiment, the average particle diameter φA of the superabrasive grains 12 is, for example, about 125 μm. In addition, 125 micrometers is only illustrated as an example to the last, and is not restricted to this size. As shown in FIG. 2, in the grindstone layer 22, the plurality of superabrasive grains 12 are arranged in non-contact with each other. At this time, the average separation distance L between the adjacent superabrasive grains 12 among the plurality of superabrasive grains 12 is substantially the same as the average grain diameter φA of the superabrasive grains 12 in FIG. The distance L need not be the same size as the average particle diameter φA of the superabrasive grains 12. The average separation distance L is arbitrarily set according to the desired degree of concentration with respect to the grindstone 10.

A known vitrified bond 14 (binding agent) bridges and bonds adjacent superabrasive grains 12 in a bridge shape to form a crosslinked portion 20 (see FIGS. 2 and 3). In the bridging portion 20, the plurality of fine particles 16 described above are arranged in an aggregated state, and the plurality of superabrasive grains 12 are arranged in a non-contact manner by interposing between the plurality of superabrasive grains 12. The plurality of fine particles 16 are each formed in a substantially spherical shape by alumina (Al ₂ O ₃ ), which is fine ceramics (corresponding to ceramics), for example. However, not limited to this aspect, the fine particles 16 may be formed of other ceramic materials. Further, the fine particles 16 may be formed by a member conventionally used as an aggregate. The size of each fine particle 16 (average particle diameter φB) is 1/5 or less than the average particle diameter φC of a granulated powder 30 described later, which is an aggregate of a plurality of fine particles 16. In the present embodiment, the average particle diameter φB of the fine particles 16 is about 1/10 of the average particle diameter φC of the granulated powder 30. The shape of the fine particles 16 is not limited to a spherical shape.

  When viewed macroscopically, the plurality of fine particles 16 disposed in the bridging portion 20 seem to be in contact with each other so that the adjacent superabrasive grains 12 are filled with the fine particles 16. Be placed. However, as shown in FIG. 3, when viewed microscopically, there are two states when there is a minute gap between adjacent fine particles 16 and when the fine particles 16 are in contact with each other. is there. When there is a minute gap, the vitrified bond 14 is interposed in the minute gap between the adjacent fine particles 16. Further, when there is no gap, the vitrified bond 14 is not interposed between the adjacent fine particles 16. However, in any case, the adjacent fine particles 16 are bonded to each other by vitrified bonds 14 covering the periphery of each fine particle 16. In addition, it is not restricted to said aspect, All between adjacent superabrasive grains 12 may have a micro clearance gap. Further, the adjacent superabrasive grains 12 do not have a minute gap and may all be in contact with each other. The effect can be obtained in the same manner.

  As shown in FIG. 2, the pores 18 are formed around the superabrasive grains 12 in which the vitrified bond 14 (binder) is crosslinked. That is, the pores 18 are formed in portions other than the plurality of superabrasive grains 12 and the vitrified bond 14 (including the plurality of fine particles 16). The pores 18 have a function of temporarily holding the discharged chips when the grindstone 10 grinds the workpiece.

(3. Manufacturing method of grindstone layer 22)
Next, a method for manufacturing the grindstone layer 22 using CBN abrasive grains will be described. The manufacturing method of the grindstone layer 22 includes a granulation step S10, a classification step S12, a mixing step S14, a pressurizing step S16, and a heating step S18, as shown in the flowchart of FIG.

  In the granulation step S10, before forming the grindstone layer 22, the plurality of fine particles 16 formed in a substantially spherical shape are adhered and granulated with a binder Bi (adhesive member) to form a plurality of granulated powders 30. Is a step of forming. Here, the granulated powder 30 is an enlarged view of a part of the granulated powder 30, and as shown in FIG. In this state, the binder Bi is bonded to each other in a state of being adhered to the outer peripheral surface of each other, thereby forming a bonded assembly. In the present embodiment, the granulated powder 30 has a substantially spherical shape. Further, the diameter of the spherical granulated powder 30 is hereinafter referred to as a powder diameter.

  The granulated powder 30 is a member that is arranged between adjacent superabrasive grains 12 in the subsequent mixing process S14 and pressurizing process S16, and determines an average separation distance L between the superabrasive grains 12. is there. As described above, in the present embodiment, the average separation distance L between the superabrasive grains 12 is determined by the degree of concentration of the desired grindstone. For this reason, in granulation process S10, each powder diameter of each granulated powder 30 aims at the powder diameter decided by the concentration degree of a grindstone, and granulated powder 30 is formed. Thereby, the granulated powder 30 having a target average powder diameter φC can be extracted by the classification step S12 described later.

  Any granulation method may be used for producing the granulated powder 30. For example, the granulated powder 30 may be granulated using a known granulator. Specifically, granulation may be performed using, for example, a “fluidized bed granulator” described in “Granulation Handbook” (edited by the Japan Powder Industry Association, 19755.5, published by Ohm). At this time, the binder Bi necessary for the production of the granulated powder 30 is at a temperature (for example, less than 600 degrees) lower than the softening point (for example, 600 degrees or more) of the vitrified bond 14 (binder). This is an erasable adhesive member. In the present embodiment, for example, PVA (polyvinyl alcohol), cellulose, or the like is used as the binder Bi. However, any adhesive member may be used as long as the above disappearance temperature condition is satisfied.

  Next, in the classification step S12, the powder diameter φC of the granulated powder 30 formed into a spherical shape in the granulation step S10 is uniform and has a desired size according to the degree of concentration of the grindstone. A plurality of granulated powders 30 having a powder diameter close to the average powder diameter φC are selected from the plurality of granulated powders 30 formed in the granulating step S10. For this reason, for example, a plurality of granulated powders 30 are sieved in the order of finer sieves to larger sieves, and granulated powders 30 having a powder diameter close to a desired size are extracted (classified). . Thereafter, the granulated powder 30 that has been selected (classified) is supplied to the mixing step S14.

  In the mixing step S14, the plurality of granulated powders 30 formed with the average powder diameter φC selected in the classification step S12, the plurality of superabrasive grains 12 before the formation of the grindstone 10, and the vitrified bond 14x in a powder state (Binder) is mixed with a known mixer or the like. Thereby, the powdered vitrified bond 14x is attached to the outer peripheral surface of the granulated powder 30 and the outer peripheral surfaces of the plurality of superabrasive grains 12, as shown in FIG. Moreover, the granulated powder 30 is arrange | positioned between the adjacent superabrasive grains 12, and the intermediate molded object 32 is formed.

  In addition to this embodiment, the mixing step S14 has a separate step of attaching vitrified bonds 14x in powder form to the outer peripheral surface of the plurality of granulated powders 30 and the outer peripheral surface of the plurality of superabrasive grains 12, respectively. You may do it. In this case, the granulated powder 30 and the superabrasive grains 12 to which the powdered vitrified bond 14x has been adhered may be mixed with a mixer or the like.

  In the pressurizing step S16, the intermediate molded body 32 (granulated powder 30 + superabrasive grains 12 + vitrified bond 14x) is charged into the mold, and the inside of the mold is pressurized to form the pressure molded body 33 (see FIG. 7). To do. Thereby, the press-molded body 33 is arranged in a state where the adjacent superabrasive grains 12 are separated by the average powder diameter φC of the granulated powder 30. That is, the adjacent superabrasive grains 12 are arranged in a state of being separated by an average separation distance L. The press-molded body 33 molded in the pressurizing step S16 is a structure in which the intermediate molded body 32 is integrally molded by applying pressure. In the present embodiment, the pressure molded body 33 has a ring shape corresponding to the grindstone layer 22.

  In heating process S18, it heats with respect to the press-molding body 33 produced | generated by pressurization process S16, and the grindstone layer 22 shown in FIG. 1 is produced | generated. In the heating step S18, after completion of the pressurizing step S12, the pressure-molded ring-shaped press-molded body 33 is extracted from the mold, and an appropriate firing temperature of the vitrified bond 14 (for example, around 1,000 ° C.). ). Accordingly, in the process of increasing to the firing temperature, first, PVA (binder Bi) formed by adhering the granulated powder 30 disappears at a temperature of 600 ° C. or less, for example. For this reason, an adhesive member space (not shown) is generated at the position where the PVA is adhered inside the granulated powder 30. At this time, in the granulated powder 30, all the PVA (binder Bi) disappears, so that the bonding force that PVA bears between the fine particles 16 disappears. For this reason, the granulated powder 30 changes to form a state in which a plurality of fine particles 16 are aggregated (hereinafter referred to as an aggregate S). For this reason, as described above, there may be a case where a minute gap is generated between the fine particles 16. However, the press-molded body 33 is pressurized by the pressurizing step S <b> 16 and is formed as the press-molded body 33. For this reason, the aggregate S of the plurality of fine particles 16 constituting the granulated powder 30 is not greatly broken by the disappearance of PVA (binder Bi).

  Thereafter, when the temperature rises to 600 ° C. or higher by heating, for example, the vitrified bond 14x adhering to the outer peripheral surface of the granulated powder 30 is melted, and the adhesive member space generated in the granulated powder 30; It flows into a space other than the adhesive member space between the plurality of fine particles 16. After that, the molten vitrified bond 14 is cooled and solidified to bond the granulated powder 30 and the plurality of fine particles 16 constituting the aggregate S together. Similarly, the vitrified bond 14x adhering to each outer peripheral surface of the plurality of superabrasive grains 12 is also melted and directed toward the aggregate S of the plurality of fine particles 16 that have previously constituted the granulated powder 30. Fluid.

  Thereafter, the melted vitrified bond 14 flows on the surface of the aggregate S of the plurality of fine particles 16, and bridges between adjacent superabrasive grains 12 to form a crosslinked portion 20. Thereby, the aggregate S of the plurality of fine particles 16 is configured to be included in the bridge portion 20. At this time, it does not matter whether a part of the aggregate S of the fine particles 16 is exposed to the external space from the surface of the bridging portion 20. In addition, pores 18 are formed around the superabrasive grains 12 in which the vitrified bond 14 (binder) is crosslinked. Thus, the ring-shaped grindstone layer 22 is manufactured (see FIG. 2). Thereafter, the baked grindstone layer 22 is fixed to the outer periphery of the core 21 using an adhesive, and the grindstone 10 is completed.

(4. Action)
Next, the operation will be described with reference to FIG. When the workpiece W is ground by the grindstone 10, for example, chips V are generated from the workpiece W, and vitrified bonds 14 between the grindstone 10 and the workpiece W, particularly between adjacent superabrasive grains 12. Grinding resistance increases at the bridging portion 20 to be crosslinked, and the bridging portion 20 is worn. However, an aggregate S of a plurality of fine particles 16 having a function of determining an average separation distance L between adjacent superabrasive grains 12 is disposed in the bridging portion 20 when the grindstone 10 is manufactured. In the aggregate S, adjacent fine particles 16 are bonded together by vitrified bonds 14 (binder).

  For this reason, as shown in FIG. 8, for example, when the surface on the workpiece W side of the bridging portion 20 is worn, any of the plurality of fine particles 16 on the workpiece W side of the bridging portion 20. 16 is subjected to great resistance by the generated chips V. However, the fine particles 16 that have received resistance are one of the plurality of fine particles 16. For this reason, only one fine particle 16 that has received resistance is detached by breaking the vitrified bond 14 that has bonded the adjacent fine particles 16 together. And even if grinding progresses and other fine particles 16 similarly receive a large resistance, only the fine particles 16 that have received the resistance fall off due to the above-described action. For this reason, as in the case of the prior art in which one large aggregate is provided between adjacent superabrasive grains 12, for example, the aggregate receives a large grinding resistance, so that it is largely destroyed and dropped off. Along with this, the vitrified bond that supported the aggregate also falls off, and there is no possibility that the superabrasive grains fall off in a short period of time. Thereby, the long-life grindstone 10 is obtained.

(5. Effect by embodiment)
According to the said embodiment, the grindstone 10 is formed in the bridge | bridging shape which bridge | crosslinks each of the some superabrasive grain 12 (abrasive grain) arrange | positioned in non-contact with each other, and the some superabrasive grain 12 (abrasive grain). And a vitrified bond 14 (binding agent) that binds each of the plurality of superabrasive grains 12 (abrasive grains), and is arranged in an aggregated state in the vitrified bond 14, and is interposed between the plurality of superabrasive grains 12. The plurality of fine particles 16 for arranging the plurality of superabrasive grains 12 in a non-contact manner and the pores 18 formed around the vitrified bond 14 are provided.

  Thus, in the vitrified bond 14 (binder) which bridge | crosslinks and couple | bonds between each superabrasive grain 12 (abrasive grain) in the shape of a bridge | bridging, it arrange | positions in the state in which the some fine particle 16 aggregated as an aggregate. For this reason, even if the grinding of the workpiece proceeds by the grindstone 10 and the bridging portion 20 of the vitrified bond 14 is worn by the chips discharged from the workpiece, the plurality of fine particles 16 may be detached in units of the fine particles 16. it can. Thereby, since the plurality of fine particles 16 are not greatly broken as a lump at a time, the vitrified bond 14 in the cross-linking portion 20 including the plurality of fine particles 16 is also detached in a large amount at a time between the superabrasive grains 12. There is no possibility that superabrasive grains 12 may fall off due to the loss of bonding force. Thereby, the lifetime of a grindstone can be improved.

  According to the above embodiment, the average particle diameter φB of each of the plurality of fine particles 16 is 1/5 or less of the average particle diameter φC of the granulated powder 30. Thereby, the granulated powder 30 can be formed satisfactorily.

  According to the above-described embodiment, the average separation distance L between two adjacent superabrasive grains 12 (abrasive grains) bonded by vitrified bond 14 (binder) among the plurality of fine particles 16 is based on the degree of concentration of the grindstone. Set accordingly. As a result, a low-concentration grindstone with a highly reduced concentration can be formed.

  According to the embodiment, in the aggregate S of the plurality of fine particles 16, the fine particles 16 are bonded to each other by vitrified bonds 14 (binder). Thereby, the bonding force between the fine particles 16 is sufficiently secured, and the bonding force between the superabrasive grains 12 (abrasive grains) bonded by the bridging portion 20 including the plurality of fine particles 16 is also sufficiently secured. .

  According to the embodiment, the plurality of fine particles 16 are ceramics having a smaller thermal expansion coefficient than that of metal. For this reason, since the plurality of fine particles 16 hardly undergo thermal expansion and contraction in the vitrified bond 14 (binder), the burden on the vitrified bond 14 (binder) can be reduced, and the life can be improved. In addition, a highly versatile material such as ceramics can be used, which is economical.

  According to the method for manufacturing the grindstone 10 of the above-described embodiment, the plurality of fine particles 16 are adhered to each other by the binder Bi (adhesive member) and granulated to form a plurality of granulated powders 30. The agglomerated powder 30 and a plurality of superabrasive grains 12 (abrasive grains) before the formation of the grindstone 10 are mixed with vitrified bond 14 (binder) in a powdered state so that the agglomerated powders 30 are adjacent to each other. A mixing step S14 in which the intermediate molded body 32 is formed by being arranged between the abrasive grains 12 (abrasive grains), and the intermediate molded body 32 is put into a mold, and the inside of the mold is pressurized to form a pressure molded body 33. The pressurizing step S16 to be performed and heating to the pressure-molded body 33 eliminates all of the binder Bi (adhesive member) forming the granulated powder 30 to form an adhesive member space between the plurality of fine particles 16, and melt Vitrified Bond 14 (Binder) And a plurality of fine particles in an aggregated state that are formed by allowing the binder Bi (adhesive member) to disappear from the granulated powder 30 while flowing into a space other than the adhesive member space between the adhesive member space and the plurality of fine particles 16. Heating process S18 which bridges between adjacent superabrasive grains 12 (abrasive grains) including 16 inside. Thereby, the grindstone 10 demonstrated above can be manufactured.

  Moreover, according to the manufacturing method of the grindstone 10 of the said embodiment, the adhesive member in granulation process S10 is the binder Bi which can lose | disappear at the temperature lower than the softening point of the vitrified bond 14 (binder). Thus, until the heating step S18, the granulated powder 30 can ensure the separation distance L between the superabrasive grains 12 (abrasive grains) and is higher than the softening point of the vitrified bond 14 (binder). After the heating step S18 baked at a temperature, the binder Bi in the granulated powder 30 is lost, the granulated powder 30 is changed to form an aggregate S of a plurality of fine particles 16, and then the lost adhesive By flowing the melted vitrified bond 14 (binder) into a space other than the member space and the adhesive member space, the bonding force between the plurality of fine particles 16 and between adjacent superabrasive grains 12 (abrasive grains) is ensured. It can be secured.

  Moreover, according to the manufacturing method of the grindstone 10 of the above embodiment, the plurality of granulated powders 30 are formed in a spherical shape, and the plurality of granulated powders 30 formed in the granulation step S10 are selected to be uniform. A granulated powder 30 having a powder diameter φC is extracted. Then, the selected granulated powder 30 is supplied to the mixing step S14. Thus, since the powder diameter φC of the granulated powder 30 that determines the separation distance L1 between the superabrasive grains 12 (abrasive grains) is uniform, the separation distance L1 between the superabrasive grains 12 (abrasive grains) Variations are suppressed and grinding resistance is stabilized. Further, the processing load applied to one grindstone is averaged, and the falling of abrasive grains can be suppressed, and the tool life can be improved.

  In addition, according to the said embodiment, in granulation process S10, it demonstrated that the adhesive powder was formed only by binder Bi and the granulated powder 30 was formed. However, it is not limited to this aspect. When the granulated powder 30 is formed, a liquid binder Bi that can disappear at a temperature lower than the softening point of the vitrified bond 14x (binder) and the powdered vitrified bond 14x are mixed to form a mixture. The two may be combined to form an adhesive member. As another method, the powdered vitrified bond 14x is attached to the surface of each fine particle 16 in advance, and then the granulated powder 30 is formed while dropping the liquid binder Bi with a granulator. The binder Bi and the vitrified bond 14x (binder) in such a state may be used as the adhesive member. As a result, in the heating step S18, the binder Bi, which is a part of the adhesive member, first disappears between the fine particles 16, and the vitrified bond 14 melts and bonds between the fine particles 16 in a heated state. . That is, when the granulated powder 30 is formed, the granulated powder 30 is heated in a state where the powdered vitrified bond 14x (binder) is contained inside. For this reason, the adjacent fine particles 16 are reliably bonded by the vitrified bond 14x disposed in the vicinity thereof being melted and then solidified, so that each fine particle 16 can obtain a stable bonding force and can be used during grinding. The desorption rate of each fine particle 16 is also stabilized.

  Moreover, according to the manufacturing method of the grindstone 10 of the said embodiment, the classification process S12 which sorts the granulated powder 30 with a powder diameter was provided. However, the classification step S12 may be omitted. Even if the resulting granulated powder 30 formed by the granulation step S10 is supplied to the steps after the classification step S12 as it is, a corresponding effect can be obtained.

  Moreover, in the said embodiment, although the grindstone 10 was made into the vitrified bond grindstone which used the vitrified bond 14 as a binder, it is not restricted to this aspect. As another embodiment, the grindstone may be a metal bond grindstone formed by a binder containing metal as a main component. Moreover, in the said embodiment, although the abrasive grain of the grindstone was used as the superabrasive grain, it is not restricted to this. The abrasive grains may be alumina-based or silicon carbide-based.

  DESCRIPTION OF SYMBOLS 10 ... Whetstone, 12 ... Abrasive grain (superabrasive grain), 14, 14x ... Vitrified bond (binder), 16 ... Fine particle, 18 ... Pore, 20 ... Cross-linking part, 21 ... Core, 22 ... Grinding wheel layer, 30 ... Granulated powder, 32 ... Intermediate molded body, 33 ... Pressure molded body, S10 ... Granulating step, S12 ... Classification step, S14 ... heating step, S14 ... mixing step, S16 ... pressurizing step, S18 ... heating step, Bi ... binder (adhesive member).

Claims (9)

A plurality of abrasive grains arranged in non-contact with each other;
A binder that bridges each of the plurality of abrasive grains and that binds each of the plurality of abrasive grains;
A plurality of fine particles arranged in a state of being aggregated in the binder, and arranged between the plurality of abrasive grains so that the plurality of abrasive grains are arranged in a non-contact manner;
Pores formed around the binder;
Whetstone equipped with. The average particle size of each of the plurality of fine particles is 1/5 or less of the average particle size of the plurality of fine particles.
The grindstone according to claim 1. Among the plurality of fine particles, an average separation distance between two adjacent abrasive grains bonded by the binder is equal to or less than an average particle diameter of the abrasive grains.
The grindstone according to claim 1 or 2. The plurality of microparticles are bound to each other by the binder;
The grindstone according to any one of claims 1 to 3. The plurality of fine particles are ceramics.
The grindstone according to any one of claims 1 to 4. A method for manufacturing a grindstone, comprising:
The grindstone is
A plurality of abrasive grains arranged in non-contact with each other;
A binder that bridges each of the plurality of abrasive grains and that binds each of the plurality of abrasive grains;
A plurality of fine particles arranged in a state of being aggregated in the binder, and arranged between the plurality of abrasive grains so that the plurality of abrasive grains are arranged in a non-contact manner;
Pores formed around the binder;
With
A granulation step of forming a plurality of granulated powder by bonding the plurality of fine particles to each other by an adhesive member and granulating;
The plurality of granulated powders and the plurality of abrasive grains before the formation of the grindstone are mixed with the binder in a powder state, and the plurality of granulated powders are respectively disposed between the adjacent abrasive grains. A mixing step to form an intermediate molded body;
A pressing step of charging the intermediate molded body into a mold and pressurizing the inside of the mold to form a pressure molded body;
By heating the pressure-molded body, a part or all of the adhesive member forming the granulated powder is lost to form an adhesive member space between the plurality of fine particles, and the molten binder is The plurality of the aggregated states formed by flowing into a space other than the adhesive member space between the adhesive member space and the plurality of fine particles and part or all of the adhesive member disappearing from the granulated powder A heating step in which the adjacent abrasive grains are cross-linked with the fine particles contained therein,
A method for producing a grindstone, comprising: The adhesive member in the granulation step is a binder that can disappear at a temperature lower than the softening point of the binder.
The manufacturing method of the grindstone of Claim 6. The adhesive member in the granulation step is a binder that can disappear at a temperature lower than the softening point of the binder and a mixture of the binder.
The manufacturing method of the grindstone of Claim 6. The plurality of granulated powders formed in the granulation step are each formed in a substantially spherical shape,
In order to supply to the mixing step, the method comprises sorting the plurality of granulated powders formed in the granulation step and extracting the granulated powder having a uniform diameter,
The manufacturing method of the grindstone of any one of Claims 6-8.

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