JP2008018532A - Method for manufacturing grinding wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding wheel which simultaneously provides high efficiency, high accuracy and high processing quality by well-balancedly controlling dressing, breaking, loading and grazing properties with high binding force of abrasive grains with binding agent. <P>SOLUTION: A preliminary molded material is manufactured by molding a grinding tool manufacturing raw material made of granule obtained by mixing super abrasive grains as abrasive grains with metallic powder as the binding agent into a sheet shape and drying the raw material. The preliminary molded material is cut into desired shapes and is sintered. A plurality of the sintered sheet cut pieces are arranged to be formed into a desired shape as a polishing grinding wheel. The binding agent made of the metallic powder is used to fill a gap between the respective sintered sheet cut pieces. The sheet cut pieces are sintered again to obtain the grinding tool. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a grinding wheel with controlled abrasive spacing produced from a preform. The obtained grinding wheel is a grinding wheel used in the precision machining field, particularly for obtaining a high efficiency, a high grinding ratio, high accuracy, and a high finished surface.

  Current grinding wheels are mainly made by uniaxial pressing or pouring. The uniaxial press method is made by filling a mold with powder and a mixture of raw materials for agglomeration and bond material, and pressing them. The pouring method is made by mixing abrasive grains and a bond material (mainly liquid resin), pouring them into a grindstone mold, drying and curing the resin portion. These grindstones are mainly used as grinding wheels using a horizontal axis surface grinder or a vertical axis rotary grinder. As shown in FIG. 4, the shape of these grindstones is a shape along the outer peripheral surface of the grindstone or the end surface of the grindstone. In order to achieve high-efficiency grinding using these grindstones, for example, a groove is formed in the grindstone surface, or the grindstone is shaped and pasted into a pellet shape, and the device is designed to improve sharpness. In operation, the grinding efficiency of the grinding wheel is not greatly improved. In particular, when abrasive grains having a small particle diameter are used, the tendency appears remarkably. The finer the particle diameter, the lower the grinding efficiency of the grindstone. Therefore, when using abrasive grains with a small particle size, a large amount of pores are provided in the grindstone, and the strength of the grindstone is lowered to make it easy to drop off. Thereby, the grinding efficiency of the grindstone is improved. However, by providing a large amount of pores in the grindstone, the strength of the grindstone is significantly reduced, and the wear of the grindstone is extremely increased.

  In order to improve the surface roughness, naturally the abrasive grain size to be used must be reduced and the tips of the abrasive grains must be aligned. At present, in order to realize this, adjustment is performed by using an elastic bond or using loose abrasive grains. That is, in both cases, the tips of the abrasive grains are aligned using the elasticity of the work material. The adverse effect of this measure is that the rigidity of the grindstone is completely eliminated because the abrasive grain tips are aligned using elasticity. Therefore, in order to obtain high dimensional accuracy, this elastic deformation becomes a harmful effect, and dimensional accuracy cannot be obtained. In this way, the grinding wheel has a reciprocal characteristic that is not necessarily related to the above relationships that determine the grinding wheel performance such as grinding efficiency and grinding ratio, grinding efficiency and finished surface roughness, finished surface roughness and dimensional accuracy. is there. In the existing grindstone, there was no means for solving these reciprocal characteristics.

  Therefore, in order to obtain a grindstone having a good grinding efficiency, a high strength Young's modulus, and a strong bonding force between the binder and the abrasive grains, the present inventors formed pores in the composition of the metal bond grindstone and made it porous. To complete the invention (Patent Documents 1 and 2). This porous metal bond is, for example, a mixture of abrasive grains and binder metal particles, compression-molded into the shape of a grindstone without using a heat-volatile binder, and the particles of the binder metal remain granular. They can be manufactured by sintering by applying a temperature and pressure that cause bonding or reaction between each other and between the binder particles and the abrasive grains. The porous metal bond grindstone produced in this way has a strong bonding force with the superabrasive grains of the binder, and has a good sharpness. Also, grinding debris generated during grinding is trapped in the pore pockets. It is expected that clogging is unlikely to occur because it is removed, and even if the abrasive cutting edge wears out, the binding material will collapse appropriately and a new cutting edge will appear, and clogging will not easily occur. The street results were obtained. In other words, the above-described grinding efficiency, grinding ratio, and dimensional accuracy could be solved at once, and sufficient results could be achieved in roughing, high-efficiency machining, and high-precision machining.

However, the grindstone invented with such a concept still has another problem, that is, the improvement of the finished surface roughness. As described above, in order to obtain a high finished surface roughness and to simultaneously realize high-efficiency and high-accuracy machining, it is not possible only to produce the grindstone. This is because, in order to obtain a high-quality finished surface roughness, it is necessary to make the abrasive grain size fine. By making the abrasive grain size fine, the grinding efficiency of the grindstone is inevitably lowered. In order to achieve high efficiency, high accuracy, and high-quality processing at once, it is necessary to use abrasive grains with a fine abrasive grain size, align the abrasive grain tips, and project the abrasive grains. The bond between the bond materials must be strengthened. In order to satisfy these conditions at the same time, it could not be realized at all with the existing commercially available grindstone, and could not be realized with only the grindstone developed by the present inventors.
JP 7-251378 A JP 7-251379 A

  In order to solve this problem, the inventors of the present invention have made it an object to increase the bonding force of the abrasive bond and adjust the distribution of the abrasive grains and the height of the tip in the abrasive grains having a fine abrasive grain size. . The present invention has a strong bonding force between the abrasive grains and the bonding material, and sharpness, spillability, clogging, crushing, etc. are controlled in a well-balanced manner, realizing high efficiency, high accuracy, and high quality processing at once. An object is to provide a grindstone that can be used.

  The present invention produces a pre-formed body by forming into a sheet shape and drying with a grinding wheel manufacturing raw material comprising a powder obtained by mixing superabrasive grains as abrasive grains and metal powder as a binder. Then, the preform is cut into a desired shape, sintered, and a plurality of the sintered sheet cut pieces are arranged so as to have a desired shape as a grinding wheel, and each sintered sheet The gist of the grinding wheel manufacturing method is characterized in that the gap between the cut pieces is filled with a binder made of metal powder and sintered again to obtain a grinding wheel.

The superabrasive grains are selected from diamond and cubic boron nitride having a Knoop hardness of 1000 or more. The binder constituting the grinding wheel manufacturing raw material is selected from the group consisting of Fe, Cu, Ni, Co, Cr, Ta, V, Nb, Al, W, Ti, Si and Zr, and superabrasive grains under heating And one or more metals that can be chemically and physically bonded to each other and can form a porous body having a porous structure phase by powder sintering.
That is, the present invention provides superabrasive grains selected from diamond and cubic boron nitride having Knoop hardness of 1000 or more as abrasive grains, and Fe, Cu, Ni, Co, Cr, Ta, V as binders. Selected from the group consisting of Nb, Al, W, Ti, Si and Zr, which can be chemically and physically bonded to superabrasive grains under heating, and a porous body having a porous structure phase by powder sintering. A preform is produced by forming into a sheet with a grinding wheel production raw material comprising a granular material obtained by mixing a metal powder composed of one or more kinds of metals that can be formed, and then drying the preform. Cut into a desired shape, sinter, and use a plurality of sintered sheet cut pieces to form the desired shape as a grinding wheel, and the gap between each sintered sheet cut piece is a metal powder Filled with a binder consisting of and sintered again It is summarized as method for manufacturing a grinding wheel, characterized in that to obtain a grinding wheel Te.

  The shape of the preform is exemplified by a sheet shape. The sheet-like preform is formed by casting or using a doctor blade method, for example. That is, in the present invention, a preform is manufactured by forming into a sheet using a casting or doctor blade method and drying, and a superabrasive grain as an abrasive grain and a metal powder as a binder are mixed. Casting with a grinding wheel manufacturing raw material consisting of the granular material obtained in this way or forming into a sheet shape using a doctor blade method and drying to produce a preform, cutting the preform into a desired shape, firing The sintered and cut sheet cut pieces are arranged in a desired shape as a grinding wheel using a plurality of sheets, and the gap between each sintered sheet cut piece is filled with a binder made of metal powder Then, the gist is a method for producing a grinding wheel, which is sintered again to obtain a grinding wheel.

The preform is cut into a desired shape, powder-sintered, and the binder constituting the grinding wheel manufacturing raw material is formed into a porous body that holds superabrasive grains by chemical and physical bonding, And after forming in this porous body, it sinters in the state by which at least the surface was transformed into ceramics, and it is set as the sintered sheet cutting piece. The obtained grindstone has a porosity of 5 to 60%, preferably 5 to 45% of the entire grindstone.
The method for producing a grinding wheel of the present invention is characterized by using the preform. A pre-formed body is assembled into an appropriate shape to produce a grindstone for obtaining a high efficiency, high grinding ratio, high precision, and a high finished surface. In order to achieve high efficiency, high accuracy, and high-quality processing at once, it is necessary to use abrasive grains with a fine abrasive grain size, align the abrasive grain tips, and project the abrasive grains. The bond between the bond materials must be strengthened. In order to satisfy these conditions simultaneously, the present invention uses the preform. In the grinding wheel of the present invention, the part constituted by the preform containing the abrasive grains is formed into a porous body that holds super abrasive grains by chemical and physical bonding. And after forming in this porous body, at least the surface is transformed into ceramics. The porous body is of a porous structure phase formed by powder sintering. The porosity of the entire grindstone is adjusted to 5 to 60%, preferably 5 to 45%.

  Provides a grinding wheel that has high bonding strength between the abrasive grains and the binding material, and has well-balanced control of sharpness, spillage, clogging, crushing, etc., enabling high-efficiency, high-accuracy, high-quality machining at once can do.

  It is said that the pores contained in the grinding wheel are used for chip evacuation during grinding, but in the case of a grinding wheel that is actually used, the porosity is used for hardness stability, that is, quality control of the grinding wheel. . Therefore, there is not much discussion about the size of the pore diameter. The role of actually discharging chips is performed by the protruding amount of abrasive grains. The pores are for easily controlling the protrusion of the abrasive grains, and naturally the pore diameter is an important factor. The porosity is a necessary factor for controlling the pore diameter. As for the existing grindstone, the rule of thumb is the highest priority, and the grinding phenomenon has not been clarified theoretically. Here, the characteristics of the ideal grinding wheel conditions are summarized below.

1. Conditions necessary for the sharpness of the grindstone (1) The amount of protrusion of the abrasive grains, and (2) the pore diameter contained in the bond or the grindstone. The pore diameter is controlled by the abrasive grain or bond particle diameter and the porosity.
(3) The higher the shared load applied to the abrasive grains, the better the cutting. Note that the load sharing increases as the abrasive grain size distribution increases. Surface roughness is poor: Cutting occurs. The shared load becomes lower as the abrasive grain size distribution is narrower. Good surface roughness: not cut.
(4) The sharper the abrasive grain tip, the better the sharpness. This is because the grinding area is larger than the contact area.
(5) The larger the abrasive grain size, the greater the removal amount. Large variation in abrasive grain diameter: The shared load increases.
2. Conditions required for dressing or truing (1) Pore diameter and porosity. The larger the porosity, the easier the dressing and truing. When the pore diameter is large, it is difficult to control the protrusion of the abrasive grains.

3. Conditions required for grinding ratio (1) Bond and abrasive holding power. Abrasive grains fall off less. The abrasive grains themselves react with the bond, not the caulking depth, and are held.
(2) Abrasive retention force (the force with which the bond retains the abrasive). In a normal bond, this is determined by how much is dive (crimped) with respect to the abrasive bond. In the case of a porous metal bond or a porous ceramic bond (Japanese Patent Laid-Open Nos. 7-251378 and 7-251379), the amount is controlled not by the amount of caulking but by reaction with abrasive grains. The grinding ratio improves depending on the degree of reaction. However, the porosity of the bond is of course also an important factor. In general, the more the reaction proceeds, the lower the porosity.
4). Thermal conductivity (1) The higher the thermal conductivity of the abrasive grains, the lower the grinding heat (the greater the heat dissipation).
(2) The lower the thermal conductivity of the bond, the lower the grinding heat (the greater the heat dissipation).
(3) When the work material is metal, the grinding heat is high (the contact between the abrasive grains and the chips is large).
(4) When the work material is ceramic (brittle material), the grinding heat is low (the contact between the abrasive grains and the chips is small). The thermal conductivity of a grinding wheel is the heat generated during grinding (especially the amount of heat that deforms the material. In particular, the material with plastic deformation during processing has a greater influence of heat (because it is attracted to the abrasive grains, After this, as the grinding proceeds, the crushing only at the tip of the abrasive grain is extended to the bond portion, and heat during grinding is transmitted to the grinding wheel portion, and the temperature of the grinding wheel becomes high. In addition to the abrasive grains, heat dissipation in the bond portion is important, and a material having high thermal conductivity is desired for the bond.

5. Work surface roughness (1) The smaller the abrasive grain size, the smoother the surface roughness (the abrasive grain protrusion is less likely to be aligned).
(2) The larger the abrasive grain size, the rougher the surface roughness (the easier the abrasive grain protrusion is).
(3) The sharper the surface, the rougher the surface roughness (the larger the shared load, the deeper the abrasive grains).
(4) The surface roughness is smoother as the sharpness is worsened (the load sharing is larger, and the abrasive grains are deeper).
(5) The surface roughness is smoother as the tips of the abrasive grains are aligned (the load sharing is uniform. The biting depth is constant).
(6) The rougher the tip of the abrasive grain is, the rougher the surface roughness is (the load sharing is uneven, the biting depth is uneven).
(7) The faster the grinding wheel peripheral speed, the smoother the surface roughness (the shorter the contact time, the smaller the cutting depth).
(8) The slower the grindstone peripheral speed, the rougher the surface roughness (the longer the contact time, the deeper the cutting depth).

  In order to realize the ideal grindstone conditions described here, it is impossible to realize the conditions by using only the existing pressing method or casting method because of the reciprocal characteristics of the grindstone. The present invention has been made to realize the ideal grinding wheel conditions, and the configuration thereof will be specifically described below.

  The present invention comprises superabrasive grains (diamond, CBN) as abrasive grains and metal powder as a binder, and this binder is formed into a porous body that holds superabrasive grains by chemical and physical bonding, In addition, a porous superabrasive grindstone is used in which at least the surface is transformed into ceramic after being formed on the porous body. The binding force between the superabrasive grains and the binder phase obtained by adjusting the porosity of the porous structure phase of the binder and transforming at least the surface of the porous body into a ceramic is strongly conspicuous. It is a porous superabrasive grindstone whose spillability, clogging property, crushing property, etc. are controlled in a well-balanced manner. Other than this grindstone can be realized, but it is desirable to use these grindstones in order to satisfy all the purposes.

  First, the first thing to consider is the distribution of abrasive grains in the grinding wheel. Moreover, the abrasive grains used are those with a fine grain size (1 to 5 microns). Although rough abrasive grains (100 to 200 microns) are possible, it is desirable to use fine abrasive grains to obtain fine surface roughness.

  Therefore, in the present invention, in order to realize these characteristics, a preformed body, for example, a sheet-shaped molded body, is used to process various shapes, thereby solving various conditions necessary for the grindstone. is there. The first feature of the grinding wheel of the present invention is that it is manufactured through a preform and has a controlled abrasive spacing. Specifically, the dispersion of the abrasive grains, the arrangement of the abrasive grains, or the abrasive grains The tip is adjusted. The surface roughness of the work surface depends on the protrusion of the abrasive grains of the grinding wheel. It is considered that a surface roughness of 50 mm or less can be easily realized by accurately aligning the tips of the abrasive grains contained in the grindstone. As the abrasive grain size becomes finer, the variation in the tip height of the abrasive grains becomes smaller as shown in FIG. That is, the tip height of a grindstone using a small abrasive grain size can be easily controlled. In this state, the surface roughness is improved, but high performance grinding cannot be realized. Therefore, the conditions necessary for high-efficiency grinding are problematic in that the protruding abrasive grains and the size of the shared weight applied to the abrasive grains are a problem (see FIG. 3B). In order to obtain the shared weight, the interval between the abrasive grains must be increased. Further, the protruding amount of the abrasive grains is realized by the difference in height between the abrasive grain portion and the bond portion of the matrix. FIG. 1 shows a schematic diagram thereof.

  A sheet-shaped grinding wheel temporary compact using the casting or doctor blade method using the above-described powder mixed with a composition comprising superabrasive grains (diamond, CBN) and metal powder as a binder. Is made. As a material used at this time, a binder or a solvent is used in order to improve the dispersion of the abrasive grains and the bond, and the handling property of a dispersing agent, a solvent, and a sheet-shaped grinding wheel. The superabrasive grains mixed with these substances and a powder body made of metal powder are mixed again to produce a sheet-shaped grinding wheel. The thickness of this sheet can be variously adjusted between 0.05 mm and 1 mm. The obtained sheet is dried to become a handleable sheet.

  This sheet can be processed into various shapes. As shown in FIG. 2, it can be processed into various shapes such as a corrugated shape, a spiral shape, a circular shape, and a rod shape. The sheet-like molded body is manufactured using a slip casting method, a doctor blade method, or the like. At this time, the raw materials contained in the sheet-like molded body are diamond abrasive grains and abrasive grains such as CBN abrasive grains, a bond material for holding the abrasive grains, and a handling property after formability is improved. The sheet-like molded body, such as a binder, is molded into a predetermined shape after drying. The shape may be various shapes such as a corrugated shape, a spiral shape, a circular shape, and a rod shape, and it is not necessary to limit one shape. That is, this shape is determined by the grinding conditions of the grinding wheel and the type of work material.

An example of a sheet-shaped grinding wheel will be given. According to the shape of the grinding wheel base (the shape shown in FIG. 1), it is processed into a shape as shown in FIGS. 2a), b) and c). The gap is held with a metal bond or other bonds to hold the sheet-like grindstone firmly. In order to improve the removability at the time of dressing, the bond is desired to have high rigidity and good removability. The bond is preferably lower than the bonding strength of the sheet-like grindstone. The characteristics of the method for producing a grinding wheel using this sheet are as follows.
1. Sheets can be made in various shapes.
2. The abrasive grains used can be very fine grains (in order to control the protruding amount of abrasive grains in units of 1 micron).
3. The abrasive grain spacing (abrasive grain ratio) is determined by the shape of the sheet.
4). The holding power of diamond abrasive grains and other abrasive grains is determined by the bond of a sheet-like grindstone.
5. The shape of the sheet can be determined depending on the grinding conditions and the type of work material.
・ In the case of heavy grinding, reduce the interval between sheets. In case of light grinding, widen the interval between grains (to make the shared load uniform).
・ In order to perform high-efficiency grinding, increase the interval. When finishing grinding, narrow the interval.

That is, the ideal grinding wheel condition described above is compared with the effect of the grinding wheel obtained in the present invention.
(Control of abrasive grain protrusion) The wear of the bonding material is made faster than the wear of the portion containing the abrasive grains.
(Control of Support Bond Material and Abrasive Bond Material) Particle Size, Bond Strength: For example, the support bond material has a larger particle size than the abrasive bond material. The strength of the porous body is reduced during sintering. That is, the abrasive bond material is less likely to fall off. When a grindstone made of the same grindstone is dressed under the same conditions, the supporting bond material portion is removed more than the grindstone portion. Thereby, the protrusion of the abrasive grains is ensured.
(Control of Bond Strength between Abrasive Grains and Abrasive Bond Material) The abrasive grains and the abrasive bond material control the bonding strength by reaction. A reaction with the bond is caused at the interface of the abrasive grains. The holding power of the abrasive grains is controlled by this reaction degree. At this time, it is desired that the bond grain size be smaller than the size of the abrasive grains. This is because in order to sufficiently hold the abrasive grains, it is necessary to increase the number of contact points (coordination number) with the abrasive grains.
(Control of the surface roughness of the work material) This depends on the protruding height of the abrasive grains, that is, the most advanced variation of the abrasive grains. Therefore, in the grindstone of the present invention, the variation of the most advanced abrasive grains is controlled by the average abrasive grain size. The variation in the size of the abrasive grains becomes narrower as the average abrasive grain diameter becomes smaller. That is, the variation is reduced. Regarding the grindstone of this invention, a fine grain is used for preparation of a sheet-like grindstone. An abrasive grain of 10 μm or less (the value depends on the grinding condition and required finished surface roughness) and an abrasive bond material are mixed to produce the grindstone shown in FIG. When this grindstone is dressed, the tip of the abrasive grains is controlled depending on the abrasive grain size. That is, the smaller the abrasive grain, the smaller the variation of the abrasive grain tip. The variation of the tip directly contributes to the surface roughness of the work material.
(Control of thermal conductivity) It can be determined by the type of bond material or abrasive bond material.

  The present invention will be described with reference to examples. The present invention is not limited to these examples.

  Diamond (grain size 30-40 μm) is used as abrasive grains, tungsten powder with high rigidity (particle size: 1-2 μm) is used as bond material, organic binder is used, diamond abrasive grains 100 parts, tungsten 34 parts, organic binder 3 parts and 9 parts of ethyl alcohol as a solvent were weighed and inserted into a polyethylene pot, and mixed for 24 hours using alumina balls. The mixture was prepared using a sheet manufacturing apparatus, with a specified sheet thickness set to 500 microns. The size of the sheet was 250 × 1000 mm, and the thickness of the sheet was measured after the volatile component ethanol was sufficiently dried. The thickness of the dried sheet was about 300 μm. The obtained sheet was cut to a size of 4 × 25, degreased in the air at 500 ° C., and then sintered in a vacuum atmosphere using a pulse current sintering method at 1400 ° C., 10 MPa, and 5 minutes. At this time, it was confirmed that WC was formed at the interface between the diamond abrasive grains and the tungsten powder, and the porosity of this was 40%.

The sintered sheets were arranged in an arrangement as shown in FIG. 5, and a tungsten powder having a large particle size (average particle size 60 μm) was used between the sheets and sintered again at a temperature of 1300 ° C. This is a heat treatment for sintering tungsten having a coarse particle diameter, and a temperature lower than the temperature of the grindstone portion was set. The obtained grindstone was bonded to an aluminum base as shown in FIG. The grindstone shape is a 6A2 type grindstone shape with an outer diameter of 150 mm, an inner diameter of 100 mm, and a thickness of 3 mm. Using this grindstone, a constant pressure test was performed using a surface grinder, and the grinding efficiency and surface roughness were measured. As a sample used for the test, a block having a zirconia (ZrO2: bending strength of 400 MPa, Vickers hardness of 13 GPa) cross-sectional shape of 3 × 5 mm was used.
[Comparative Example 1]

The grindstone of Example 1 was laminated, and a grindstone having a thickness of 3 mm and the same shape as that of Example 1 was produced. At this time, a grindstone hollowed in a donut shape was attached to the base without controlling the abrasive interval of the grindstone.
[Comparative Example 2]

  As a comparative test, a vitrified diamond grindstone in which the abrasive grains of Example 1 were hardened with a glassy bond was produced. The shape of the grindstone was the same as in Example 1, and the porosity of the grindstone was 45%.

"result"
The grindstone of Example 1 was able to grind zirconia as a work material at a grinding speed about 4 times that of the grindstone of Comparative Example 1 and about 5 times that of the grindstone of Comparative Example 2. The grinding ratio was 3 times that of Comparative Example 1 and 10 times that of Comparative Example 1. The surface roughness of the work material was the same as that of Comparative Example 1 and was about half that of Comparative Example 2. This result shows that the grindstone of Example 1 is remarkably excellent in grinding efficiency, and is a result that a high efficiency, a high grinding ratio, and a high finished surface roughness can be realized at the same time.

  Diamond (grain size: 2 μm) is used as abrasive grains, tungsten powder with high rigidity (particle size: 0.3 μm) is used as bond material, organic binder is used, diamond abrasive grains are 100 parts, tungsten is 34 parts, and organic binder is 3 parts. A portion of 12 parts of ethyl alcohol measured as a solvent was inserted into a polyethylene pot and mixed for 24 hours using alumina balls. The mixture was prepared using a sheet manufacturing apparatus, with a specified sheet thickness set to 500 microns. The size of the sheet was 250 × 1000 mm, and the thickness of the sheet was measured after the volatile component ethanol was sufficiently dried. The thickness of the dried sheet was about 300 μm. The obtained sheet was cut at a size of 4 × 25, degreased at 500 ° C. in the air, and then sintered in a vacuum atmosphere using a pulse current sintering method at 1300 ° C., 10 MPa, and 5 minutes. At this time, it was confirmed that WC was formed at the interface between the diamond abrasive grains and the tungsten powder, and the porosity of the WC was 50%.

The sintered sheets were arranged in an arrangement as shown in FIG. 6, and a tungsten powder having a large particle size (average particle size of 50 μm) was used between the sheets, and sintered again at a temperature of 1250 ° C. This is a heat treatment for sintering tungsten having a coarse particle diameter, and a temperature lower than the temperature of the grindstone portion was set. The obtained grindstone was bonded to an aluminum base as shown in FIG. The grindstone shape is a 6A2 type grindstone shape with an outer diameter of 150 mm, an inner diameter of 100 mm, and a thickness of 3 mm. Using this grindstone, a constant pressure test was performed using a surface grinder, and the grinding efficiency and surface roughness were measured. The sample used for the test was a silicon nitride (Si 3 N 4: bending strength 500 MPa, Vickers hardness 15 GPa) block having a cross section of 3 × 5 mm.
[Comparative Example 3]

The grindstones of Example 2 were stacked, and a grindstone having a thickness of 3 mm and the same shape as in Example 1 was produced. At this time, a grindstone hollowed in a donut shape was attached to the base without controlling the abrasive interval of the grindstone.
[Comparative Example 4]

As a comparative test, a vitrified diamond grindstone in which the abrasive grains of Example 2 were hardened with a glassy bond was produced. The shape of the grindstone was the same as in Example 1, and the porosity of the grindstone was 45%.

"result"
The grindstone of Example 2 was able to grind silicon nitride as a work material at a grinding speed about 10 times that of the grindstone of Comparative Example 3 and about 20 times that of the grindstone of Comparative Example 4. The grinding ratio was 3 times that of Comparative Example 3 and 10 times that of Comparative Example 4. The surface roughness of the work material was about half that of Comparative Examples 3 and 4. As a result, the grindstone of Example 2 has a grinding performance equivalent to that of coarse abrasive grains while having a grain size of about 2 μm, and is a fixed abrasive grain, and the finished surface roughness is up to 50A. I made it possible. This result was the result of achieving high efficiency, high grinding ratio, and high finished surface roughness at the same time.

Diamond (particle size: 30-40 μm) is used as the abrasive, titanium powder (particle size: 2 μm) is used as the bonding material, organic binder is used, diamond abrasive is 100 parts, titanium powder is 120 parts, organic binder is 10 parts, A solvent weighed 60 parts of ethyl alcohol was inserted into a polyethylene pot and mixed for 24 hours using alumina balls. The mixture was prepared using a sheet manufacturing apparatus, with a specified sheet thickness set to 500 microns. The size of the sheet was 250 × 800 mm, and the thickness of the sheet was measured after sufficiently drying volatile ethanol. The thickness of the sheet after drying was about 250 μm. The obtained sheet was cut into 10 pieces with dimensions of 4 × 100, processed into a corrugated shape as shown in FIG. 2A, degreased in the atmosphere at 400 ° C., and then 800 ° C. in a vacuum atmosphere. Sintering was performed for 1 hour. At this time, it was confirmed that TiC was formed at the interface between the diamond abrasive grains and the titanium powder, and the porosity of this was 30%. The sintered sheet was subjected to nitriding treatment in a vacuum furnace at a temperature of 750 ° C. under a nitrogen gas pressure of 5 atm. It was confirmed by an X-ray diffraction experiment that the titanium portion in the sheet was modified into TiN ceramics by this nitriding treatment. In this treatment, the degree of nitriding was 80%. Further, as a result of comparing the Vickers hardness with a sintered body (titanium bond grindstone) before nitriding treatment, the Vickers hardness increased by 20 times from 0.3 to 6 GPa at the same porosity (about 30%). The corrugated sheet subjected to nitriding treatment is arranged on the circumference on the carbon base, and the gap between the sheets is sintered again at a temperature of 800 ° C. using titanium powder having a large particle diameter (average particle diameter of 30 μm), Nitriding was performed at the same temperature. This is a heat treatment for sintering titanium powder having a coarse particle diameter as in Example 1, and is a treatment aimed at increasing the strength of the bond portion other than the grindstone and enhancing the rigidity of the entire grindstone. The obtained grindstone was bonded to an aluminum base as shown in FIG. The grindstone shape is a 6A2 type grindstone shape with an outer diameter of 150 mm, an inner diameter of 100 mm, and a thickness of 3 mm. Using this grindstone, a constant pressure test was performed using a surface grinder, and the grinding efficiency and surface roughness were measured. As a sample used for the test, a block having a zirconia (ZrO2: bending strength of 400 MPa, Vickers hardness of 13 GPa) cross-sectional shape of 3 × 5 mm was used.
[Comparative Example 5]

A corrugated titanium grindstone that was not nitrided in the grindstone of Example 1 was made into a grindstone having the same shape as in Example 1.
[Comparative Example 6]

  As a comparative test, a vitrified diamond grindstone in which the abrasive grains of Example 1 were hardened with a glassy bond was produced. The shape of the grindstone was the same as in Example 1, and the porosity of the grindstone was 45%.

  The grindstone of Example 3 was able to grind zirconia as the work material at a grinding speed about 50 times that of the grindstone of Comparative Example 5 and about 5 times that of the grindstone of Comparative Example 6. The grinding ratio was 50 times that of Comparative Example 5 and 10 times that of Comparative Example 6 and the surface roughness of the work material was about half that of Comparative Example 5 and Comparative Example 6. Since the grindstone of Comparative Example 5 was a titanium bond grindstone, it was plastically deformed during grinding, and thereafter the work material could hardly be removed. As a result, since the grindstone of Example 3 has a wavy shape of the grindstone, the grindstone shows a high grinding efficiency even though the grindstone has a small particle diameter, and the bond portion is converted into ceramics. Further, since it is made of ceramics, the grinding performance was remarkably superior to those of Comparative Examples 5 and 6.

It is a schematic diagram explaining that the grinding wheel of the present invention is a grinding wheel for obtaining a high efficiency, a high grinding ratio, high accuracy, and a high finished surface. A sheet-shaped preform for producing a grinding wheel with controlled abrasive spacing, formed from the grinding wheel production raw material of the present invention, can be processed into (a) a waveform, (b) a spiral shape, and (c) a circle. It is drawing to explain. (A) It is a schematic diagram explaining that the dispersion | variation in the tip height of an abrasive grain becomes small, so that an abrasive grain diameter becomes finer generally. (B) It is a schematic diagram explaining that the conditions generally required for high-efficiency grinding are the size of the protrusion of an abrasive grain and the shared weight applied to the abrasive grain. It is drawing which made the shape for the existing grindstone (a) for horizontal axis plane research, and (b) vertical axis rotary. The (a) side view and (b) top view which show arrangement | positioning of the grinding stone made as an experiment in Example 1 of this invention are shown. The (a) side view and (b) top view which show arrangement | positioning of the grinding stone made as an experiment in Example 2 of this invention are shown.

Claims (7)

  A pre-formed body is manufactured by forming into a sheet shape by using a grinding wheel manufacturing raw material consisting of powder obtained by mixing superabrasive grains as abrasive grains and metal powder as a binder, and drying the pre-formed body. The formed body is cut into a desired shape, sintered, and a plurality of sintered sheet cut pieces are arranged so as to have a desired shape as a grinding wheel using a plurality of pieces, and a gap between each sintered sheet cut piece Is a method for producing a grinding wheel characterized by filling with a binder made of metal powder and sintering again to obtain a grinding wheel.   The method for producing a grinding wheel according to claim 1, wherein the superabrasive grains are selected from diamond and cubic boron nitride having a Knoop hardness of 1000 or more.   The binder constituting the grinding wheel manufacturing raw material is selected from the group consisting of Fe, Cu, Ni, Co, Cr, Ta, V, Nb, Al, W, Ti, Si and Zr, and superabrasive grains under heating The method for producing a grinding wheel according to claim 1 or 2, comprising at least one metal capable of being chemically and physically bonded to each other and capable of forming a porous body having a porous structure phase by powder sintering.   The method for producing a grinding wheel according to claim 1, 2 or 3, wherein the preform is produced by molding into a sheet using a casting or doctor blade method and drying.   The preform is cut into a desired shape, powder-sintered, and the binder constituting the grinding wheel manufacturing raw material is formed into a porous body that holds superabrasive grains by chemical and physical bonding, The method for producing a grinding wheel according to any one of claims 1 to 4, wherein after the formation of the porous body, at least the surface thereof is sintered into a state of being transformed into ceramics to obtain a sintered sheet cut piece. .   The method for producing a grinding wheel according to claim 5, wherein the obtained grindstone has a porosity of 5 to 60%. The method for producing a grinding wheel according to claim 6, wherein the obtained grinding wheel has a porosity of 5 to 45%.