JPH10128668A - Super-abrasive grain grinding wheel and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heighten grinding efficiency and mechanical strength and uniformly continue grinding performance by providing binder particles having a bulk density within a specified multiple of super abrasive grain and a thermal expansion coefficient within a specified multiple of super abrasive grain. SOLUTION: A super abrasive grain grinding wheel 10 uses fine diamond particles or cBN particles which have a high hardness and the average particle diameter of 0.5μm-60μm as super-abrasive grains 1, so that soft ground material such as ceramics or cemented carbide is precisely ground. The bulk density of binder particles 2 is in the range of 0.5-2 times as large as that of super abrasive grain, and at the time of mixing in manufacture, super abrasive grains 1 and binder particles 2 can be uniformly dispersed. Accordingly, uniform cutting capability can be continued until the grinding wheel is used up. A thermal expansion coefficient of the binder particle 2 is in the range of 0.3-3 times as large as that of super abrasive grains 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superabrasive grindstone used in the field of precision machining, and more particularly to a superabrasive grindstone having a high grinding efficiency and excellent physical strength, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, difficult-to-grind materials, such as ceramics and cemented carbide, which are difficult to grind, have been frequently used, and there has been an increasing demand for highly efficient and precise grinding of these materials. For example, when structural ceramics are used for machine parts and the like, a grinding process is required in order to give shapes and determine dimensions in the final production process. For precision machining of difficult-to-grind materials such as ceramic materials, grindstones containing so-called “super-abrasive grains” such as diamond and cubic boron nitride (hereinafter referred to as “cBN”) are used as abrasive grains.

[0003] A grindstone containing such superabrasive grains is called a "superabrasive grindstone", and is generally manufactured by bonding superabrasive grains with a binder and molding. As the binder, those using synthetic resin are called resin-bonded grindstones, those using glassy materials are called vitrified bond grindstones, and those using metal are called metal-bonded grindstones. .

Recently, as represented by an integrated circuit using a thin-film process, as the density of elements has increased and spread, the width of the cutting allowance for the substrate has been reduced for economic reasons.
For example, fine cutting such as 0.3 mm or less has been required, and a thin blade grinding wheel capable of performing this cutting has been required.

Conventionally, non-porous metal bond grindstones having high rigidity have been used as thin blade grindstones used for precision grinding of hard-to-grind ceramics and the like from the viewpoint of the mechanical strength of the grindstones. In general, a metal-bonded grindstone is formed by uniformly dispersing abrasive grains in a binder and by electroforming or sintering. As the binder, for example, Cu-Sn
A bronze-based soft metal such as a copper-based, Cu-Sn-Co-based, or Cu-Sn-Fe-Co-based metal is used.

Since these conventional metal-bonded grinding wheels are non-porous, the mechanical strength of the grinding wheel itself is much higher than other vitrified bond wheels or resin-bonded grinding wheels, and is particularly important for grinding difficult-to-ground materials. Although the holding power of the abrasive grains by the bonding material is excellent, the structure of the bonding material is dense and hard to wear, so the phenomenon that new cutting edges of the abrasive grains constantly appear on the surface of the grinding stone, so-called `` self-generated cutting action '' is small. In addition, since there are no pores that help discharge chips generated during grinding, clogging is likely to occur, grinding resistance increases, and so-called "sharpness" drops, making it difficult to perform highly efficient machining of the workpiece. there were.

[0007]

To solve these problems, a grindstone using cast iron as a binder has been proposed (see Japanese Patent Application Laid-Open No. 3-264263). This cast iron bond whetstone has high rigidity and the bridging fracture occurs without causing plastic flow in the binder structure. Therefore, it has many advantages such as difficulty in clogging, but its strength is too high and its dressing (sharpening) property is high. There was a problem that was bad.
Also, fine powder of cast iron is generally difficult to obtain and expensive.

[0008] A porous metal bond grinding wheel has been proposed to improve the disadvantages of the cast iron bond grinding wheel (see Japanese Patent Application Laid-Open No. 7-251379). This porous metal bond whetstone uses metal powder as a binder, and superabrasive grains, which are abrasive grains, are dispersed and held in a porous structure of a binder formed by powder sintering, so that the porosity thereof is reduced. By adjusting, the mechanical strength of the grinding wheel and / or the holding power of the abrasive grains can be controlled. This whetstone does not cause clogging, is capable of continuous grinding for a long time, has excellent dressing properties, and has a high grinding ratio.
Because of the pores, the rigidity of the grindstone itself is low, and it has been difficult to manufacture a grindstone requiring high rigidity such as a thin blade grindstone.

The above-mentioned porous metal bond grindstone for precision processing is manufactured by a powder sintering method in which fine powder of abrasive grains and a binder is mixed and put into a mold and sintered under pressure. In this case, there is a problem that it is difficult to uniformly disperse the superabrasive grains and the fine powder of the binder, and it is easy to separate them from each other, so that it is difficult to obtain a uniform grindstone.

[0010] As described above, in the grinding wheel for precision machining, the grinding performance and the mechanical strength of the grinding wheel are contradictory elements, and it is difficult to achieve both. It was difficult to uniformly mix and disperse the particles and the binder. The present invention has been made to solve these problems, and therefore, the object is to achieve both high grinding efficiency and high mechanical strength, and that superabrasive grains are uniformly mixed and dispersed in a binder, It is an object of the present invention to provide a superabrasive grindstone in which grinding performance is maintained uniformly and a method for producing the same.

[0011]

As a means for solving the above-mentioned problems, the present invention provides a method for firing super-abrasive grains of diamond or cBN having an average particle diameter in the range of 0.5 μm to 60 μm and binder particles. Consisting of binders, the binder particles
A superabrasive grain having a bulk density in the range of 0.5 to 2 times the superabrasive grain and a coefficient of thermal expansion in the range of 0.3 to 3 times the superabrasive grain. provide.

In the above, the binder is W, Zr, C
It is preferably at least one element selected from the group consisting of elemental elements consisting of r, Mo, Ta, and V, carbides of W and Si, Ti, Si, oxides of W, and nitrides of Si.

[0013] The present invention also provides an average particle size of 0.5 μm to 6 μm.
A superabrasive made of diamond or cBN in the range of 0 μm, a bulk density of 0.5 to 2 times the superabrasive, and a 0.3 to 3 times of the superabrasive. The powder mixture obtained is mixed with binder particles having a coefficient of thermal expansion of 0.5 Tm (Tm is the melting point or liquid phase formation temperature of the binder represented by absolute temperature ゜ K) or less. The present invention provides a method for producing a superabrasive grindstone comprising sintering.

In the above-mentioned production method, it is preferable that the mixing of the superabrasive grains and the binder particles is carried out in the presence of a volatile organic solvent and then drying to obtain a powder mixture. The sintering is preferably performed using a spark plasma sintering method (hereinafter, referred to as “SPS method”) or a hot isostatic press sintering method (hereinafter, referred to as “HIP method”). Preferably, the sintering is performed under a pressure in the range of 5 MPa to 50 MPa.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to an embodiment. As schematically shown in FIG. 1, a superabrasive grindstone 10 of this embodiment is made of a sintered body of superabrasive grains 1 of diamond or cBN and binder particles 2. The average particle size of the superabrasive grains is in the range of 0.5 μm to 60 μm, and the binder particles 2 are formed of, for example, W (tungsten).
The bulk density in the range of 5 to 2 times and 0.3 of the superabrasive 1
Thermal expansion coefficient in the range of 2 to 3 times.

The superabrasive grindstone 10 can be manufactured, for example, by the following method. That is, the super-abrasive grains 1 made of diamond or cBN having an average particle diameter in the range of 0.5 μm to 60 μm, and in the range of 0.5 to 2 times the super-abrasive grains 1 formed of, for example, W and the like. And the binder particles 2 having a bulk density of 0.3 and a coefficient of thermal expansion in the range of 0.3 to 3 times that of the superabrasive grains 1 are uniformly mixed in the presence of a volatile organic solvent such as methanol. The powder mixture obtained by drying the solvent is used, for example, by using the SPS method.
A pressure in the range of 5 MPa to 50 MPa is applied, and 0.5 T
Sintering is performed at a temperature equal to or lower than m (Tm is the melting point of the binder or the liquid phase generation temperature represented by the absolute temperature ゜ K).

The obtained superabrasive grindstone 10 uses fine diamond particles or cBN particles having a high hardness and an average particle size of 0.5 μm to 60 μm as the abrasive particles 1. Can be ground precisely.

If the bulk density of the binder particles 2 is in the range of 0.5 to 2 times that of the superabrasive grains, the bulk density of the superabrasive grains 1 and the bulk density of the binder particles 2 are close to each other. During mixing at the time of production, superabrasive grains 1 and binder particles 2 can be uniformly dispersed. For this reason, the superabrasive grains 1 are uniformly distributed throughout the grindstone body after sintering without uneven distribution, and a uniform cutting ability can be maintained until the grindstone is used up.

The coefficient of thermal expansion of the binder particles 2 is, for example, W
(Coefficient of thermal expansion: 4.6 × 10 ⁻⁶ ), the super-abrasive 1 (for example, the coefficient of thermal expansion of diamond: 3.0 × 10 ⁻⁶ ) has a ^0.1 μm.
If it is within the range of 3 to 3 times, the mismatch between the materials due to the difference in the coefficient of thermal expansion generated during manufacturing, for example, during cooling after sintering, for example, the difference in the thermal shrinkage rate causes The internal stress generated at the sintering interface is relaxed, resulting in the prevention of minute cracks, warping of the grinding wheel, undulation, etc.
The physical properties and formability of the superabrasive stone are improved.

Next, various elements constituting the superabrasive grinding wheel of the present invention will be described in detail. The superabrasive grains 1 used in the superabrasive grain wheel 10 of the present invention are diamond or cBN. For example, in the case of finely processing a hard object to be ground such as a ceramic material, it is preferable to use diamond having the highest hardness. This diamond may be a single crystal or a polycrystal, and any of natural diamond and artificial diamond can be used.

However, when processing an iron-based workpiece, there is a problem in using diamond. In this case, it is preferable to use cBN. This cBN may be either single-crystal or polycrystalline. The superabrasive grains used in the present invention may be a mixture of any two or more of the above.

The average particle size of superabrasive 1 is 0.5 μm to 60 μm.
μm. If the average particle size is less than 0.5 μm, the particles are too fine and the grinding ability is not sufficiently exhibited,
If it exceeds m, for example, when this grindstone is used for fine grinding or lapping, the finish of the surface to be ground becomes rough, which is inappropriate.

The binder has a coefficient of thermal expansion in the above range and a bulk density of the particles in the above range, and forms a superabrasive and a sintered body when hot pressure is applied. Any of these can be used. Examples of preferred binders include simple elements consisting of W, Zr, Cr, Mo, Ta and V, carbides of W and Si, Ti, S
i, an oxide of W, a nitride of Si, and the like. In particular, W is a suitable binder when diamond is used as the superabrasive.

Table 1 shows the melting point, the coefficient of thermal expansion, the particle size of the particles, and the bulk density at the particle sizes of the superabrasives (diamonds) and typical binders. As a reference,
Although it is out of the range as a binder of the superabrasive grinding wheel of the present invention,
Conventionally commonly used binders, Co and Fe
Table 2 shows the same data for and.

[0025]

[Table 1]

[Table 2]

The particle size of the binder particles 2 is not particularly limited as long as it satisfies the above-mentioned bulk density condition, but is generally in the range of 5% to 50% of the average particle size of the superabrasive particles. Is preferred. If the particle size of the binder particles with respect to the superabrasive particles exceeds 50%, the contact area between the superabrasive particles and the binder particles in the state where the mixture is filled in the mold during sintering becomes small, Insufficient bonding force reduces the strength of the grindstone itself. Also 5%
If it is less than 10, the contact area is sufficiently large, so that there is no problem in the bonding force at the time of sintering, but the porosity and the pore diameter are small, and the sintered product is not much different from the non-porous metal bond grindstone.

In the superabrasive grindstone 10 of the present invention, the mixing ratio of the superabrasive grains and the binder is in the range of 1: 0.5 to 1: 3 in the volume ratio of the superabrasive grains: the binder particles. Is preferred. If the ratio of the binder is less than 1: 0.5, the density of the superabrasive grains is too high, so that the strength of the sintered body is reduced and dropout or the like is likely to occur. When the ratio of the binder is larger than 1: 3, the grinding ability becomes insufficient.

Since the superabrasive grindstone 10 of the present invention is formed by surface sintering of a granular material, as shown in FIG. 1, its structure contains many pores 4 and becomes porous. ing. The porosity is preferably in the range of 5% to 60%. If the porosity is less than 5%, the structure of the binder becomes dense and hard to wear, so that not only the autogenous cutting action hardly occurs, but also a pocket for accommodating chips generated during grinding (reference numeral 5 in FIG. 1). 2) capacity is insufficient, and the circulation of the cooling liquid is also insufficient, so that clogging and melting due to frictional heat are likely to occur. If the porosity exceeds 60%, the physical properties of the grindstone itself are reduced, and dropout or crushing is likely to occur. From these viewpoints, the porosity is more preferably in the range of 5% to 45%. The porosity can be adjusted by selecting various conditions such as the particle size of the superabrasive grains and the binder particles, the mixing ratio, the pressure applied during sintering, and the presence or absence of volatile inclusions during mixing.

Next, the method for producing a superabrasive grindstone of the present invention will be described in detail. This manufacturing method is roughly divided into a mixing step and a sintering step. The superabrasive grains 1 and the binder particles 2 are uniformly mixed in the mixing step. This mixing is preferably performed by stirring and mixing the superabrasive grains and the binder particles in the presence of a volatile organic solvent, for example, with a ball mill or the like, and then drying the solvent.

As the volatile organic solvent, any of hydrocarbons, alcohols, esters, ethers and the like can be used.
Preferably, ethanol or methanol is used.
Due to the presence of the volatile organic solvent, lubricity between particles during stirring and mixing is improved, and more uniform dispersion is achieved,
Since friction between particles is alleviated, wear of the cutting edge of the superabrasive grains and pulverization of the binder are prevented. This volatile organic solvent is evaporated to dryness, preferably under reduced pressure, prior to sintering to obtain a powder mixture.

The sintering is preferably performed by using the SPS method or the HIP method. These are all powder sintering methods, and according to these sintering methods, diffusion, reaction, solid solution, etc., at the interface between the superabrasive grains and the binder particles are promoted, and the superabrasive grains and the binder particles are formed. Is strengthened.

The SPS method can be performed using, for example, a discharge plasma sintering apparatus (SPS apparatus) schematically shown in FIG. In FIG. 2, this SPS device is a cylindrical die 2.
1, a core 22 inserted coaxially with the die 21,
An upper punch 23 and a lower punch 24 fitted to the die 21 and the core 22, and upper and lower punches 2
And a thermocouple 26 for measuring the temperature of the powder mixture 25 sandwiched between 3 and 24. The upper punch 23 and the lower punch 24 are connected to a press (not shown) for pressing the powder mixture 25 filled in the gap between the die 21 and the core 22 from above and below. 25
Each electrode for applying a pulse current to the electrodes is constituted. In this SPS device, at least a portion sandwiched between upper and lower punches 23 and 24 is a chamber (not shown).
And the inside of this chamber is evacuated to a vacuum or
Alternatively, an inert gas is introduced.

A predetermined amount of the powder mixture 25 of the superabrasive grains and the binder is filled in a gap between the die 21 and the core 22 formed into a predetermined grinding stone shape, and the inside of the chamber is evacuated, or After being replaced with an inert gas, the upper punch 23 and the lower punch 24 preferably use a pressure of 5 MPa to 50
It is compressed at a pressure in the range of MPa and then a pulsed current is applied.

According to this SPS method, the powder mixture 25 can be uniformly and quickly heated to a predetermined sintering temperature by adjusting the current, and the temperature control and the sintering time control are strictly controlled. It can be carried out. Examples of the SPS device that can be used in the above-described SPS method include a model SPS-2050 type discharge plasma sintering device manufactured by Sumitomo Coal Mining Co., Ltd.

On the other hand, in the HIP method, for example, wax or the like is added as a molding aid to a mixture of superabrasive grains and binder particles,
Using a uniaxial press or the like, pressurize to a pressure of about 10 MPa to produce a powder compression molded product, and heat the powder compression molded product to about 800 ° C. in a vacuum to remove wax and perform preliminary sintering. After shaping, the main body is sintered by applying heat and pressure in a vacuum or an inert gas atmosphere to obtain a sintered body.

In any of the sintering methods, the sintering temperature is 0.5 Tm or less. Here, Tm is the melting point or liquid phase generation temperature of the binder particles represented by the absolute temperature ΔK.
By setting the sintering temperature to 0.5 Tm or less, the binder particles are fused only by their surface layers, exhibiting a self-destructive cutting action with a suitable collapsibility while maintaining the strength of the grindstone itself. Good grindability is maintained.

The lower limit of the sintering temperature depends on the characteristics of the binder particles used and the sintering pressure, but is set to a temperature at which at least the particles can fuse to each other to form a fusion phase. This lower limit temperature is usually 600 ° C. or higher. From this viewpoint, a practically preferable sintering temperature range is 600 ° C. to 15 ° C.
It is within the range of 00 ° C.

In sintering in a die in the powder sintering method, the pressure applied to the powder mixture is 5 MPa to 50 M
It is preferable to be within the range of Pa. If the pressure is less than 5 MPa, the porosity of the sintering whetstone is too high,
The mechanical strength of the whole grindstone is greatly reduced. If the pressure is 5
If it exceeds 0 MPa, the porosity of the grindstone will be too low to be almost void-free, and the grinding efficiency will be greatly reduced.

In any of the sintering steps, sintering is preferably performed in an atmosphere having an inert gas or an oxygen partial pressure of 0.01 MPa or less. If sintering is performed by applying heat pressure in an atmosphere where the oxygen partial pressure exceeds 0.01 MPa, the superabrasive grains and the binder particles may be deteriorated. As an inert gas,
N ₂ or Ar is preferably used.

Next, examples of the present invention will be described. Each of these examples has an outer diameter of 120 mm, an inner diameter of 114 mm,
It is a superabrasive grain formed in a cup shape having a thickness of 3 mm, and is manufactured according to the above-described embodiment of the present invention.

Example 1 A ball mill was charged with 100 parts by volume of the following superabrasive grains and 128 parts by volume of binder particles.
Further, 200 parts by volume of methanol was added and mixed with stirring for 24 hours.

The resulting slurry mixture was taken out of the ball mill, and ethanol was removed by drying under reduced pressure to obtain a powder mixture in which superabrasive grains were uniformly dispersed in the binder. Next, this mixture was filled in the gap between the die 21 and the core 22 of the SPS apparatus shown in FIG. 2 and sintered under the following conditions to produce a cup-type superabrasive wheel having the above dimensions. Sintering temperature: 1260 ° C Sintering pressure: 20 MPa

When the cross section of the obtained superabrasive grindstone of Example 1 was magnified 10000 times with an electron microscope and observed, the diamond superabrasive grains 1 were separated from each other as schematically shown in FIG. Uniformly distributed in the sintered structure of the binder particles 2,
The superabrasive grains 1 and the binder 2 particles were fused to each other at their contact surfaces 3, and a large number of pores 4 were formed in the sintered structure of the binder particles 2. Table 3 shows the porosity and physical properties of the superabrasive grindstone of Example 1.

Example 2 A superabrasive wheel of Example 2 was manufactured according to Example 1 using the following materials and manufacturing conditions. Table 3 shows the porosity and physical properties of the obtained superabrasive grindstone of Example 2.

Example 3 A superabrasive grindstone of Example 3 was manufactured according to Example 1 using the following materials and manufacturing conditions. Table 3 shows the porosity and physical properties of the obtained superabrasive grindstone of Example 3.

Example 4 A superabrasive grindstone of Example 3 was manufactured according to Example 1 using the following materials and manufacturing conditions. Table 3 shows the porosity and physical properties of the obtained superabrasive grindstone of Example 4.

(Comparative Example 1) For comparison, a superabrasive grindstone of Comparative Example 1 was manufactured according to the following composition and manufacturing conditions according to the composition and manufacturing method shown in Example 1. Comparative Example 1
Is an example in which the thermal expansion coefficient of the binder particles is out of the range of the present invention. Table 3 shows the porosity and physical properties of the obtained superabrasive grindstone of Comparative Example 1.

(Comparative Example 2) According to the composition and the manufacturing method shown in Example 1, a superabrasive grindstone of Comparative Example 2 was manufactured according to the following composition and manufacturing conditions. Comparative Example 2 is an example in which the bulk density of the binder particles is out of the range of the present invention. Table 3 shows the porosity and physical properties of the obtained superabrasive grindstone of Comparative Example 2.

Comparative Example 3 For comparison, a commercially available vitrified grindstone “# 1200” whose porosity and physical properties are shown in Table 3 was used as a comparative example 3.

[0050]

[Table 3]

(Grinding Performance Test) A grinding test was performed on each of the above samples. As a grinding test, a wet constant-pressure grinding method that was not affected by the Young's modulus of the grinding wheel, the rigidity of the grinding machine, and the horsepower was adopted. As the object to be ground, a block of Al ₂ O ₃ .TiC ceramics (bending strength: 588 MPa, micro Vickers hardness: 19 GPa) having a cross section of 2 mm × 5 mm was used.

FIG. 3 shows that each grindstone sample is mounted on a grinder, and the cross section of the object to be ground is pressed against the grinding surface of each sample for a predetermined time (30 seconds).
a, the amount of grinding (mm ³ ) was measured when sequentially changing to 0.5 MPa, 1 MPa, and 2 MPa. FIG. 4 shows that a constant grinding pressure (1 M
Pa), the grinding time is 30 seconds, 60 seconds, 120 seconds, 240
And 480 seconds were measured for the amount of grinding (mm ³ ). FIG. 5 shows a change in the grinding speed with respect to each grinding time when the grinding speed for 30 seconds from the start of grinding is set to 100%.

From the results of these physical property tests and grinding performance tests, the following matters become clear. (1) From the results in Table 3, the samples of Examples 1 to 3
The binder is W, and its bulk density is 0.75 to 1.81 times that of the superabrasive, so it is in the range of 0.5 to 2 times, and the coefficient of thermal expansion is that of the superabrasive. Since it is 1.53 times, it is in the range of 0.3 to 3 times. These materials have physical properties, particularly Young, as compared with Comparative Example 2 (Fe), whose bulk density is 2.2 times that of the superabrasive, and Comparative Example 1 (Co), whose coefficient of thermal expansion is 4.17 times that of the superabrasive. It can be seen that the ratio and the micro Vickers hardness are excellent. In Example 4, similarly, the bulk density of the binder (Cr) is 0.83 times that of the superabrasive grains, and the thermal expansion coefficient is 2.16 times that of the superabrasive grains, so that the physical properties are excellent.

From the results shown in FIG. 3, the sample of Example 3 has a larger amount of grinding in a fixed time than the comparative examples.
It can be seen that the stone is sharp. Therefore, the number of steps in the grinding process can be reduced as compared with the related art. In addition, when the grinding pressure is increased, the amount of grinding increases linearly with the increase of the grinding pressure, indicating that the grinding wheel is easy to control the grinding accuracy. On the other hand, in each of the grindstones of the comparative examples, the grinding amount does not increase even if the grinding pressure is increased due to clogging, and it is difficult to control and maintain the grinding accuracy.

From the results shown in FIG. 4, it can be seen that the sample of Example 3 has a larger grinding amount with respect to the grinding time than each of the comparative examples, and is a grindstone that maintains the sharpness. Also, from the results in FIG. 5, the samples of Examples 1 to 3 show a small change in the grinding speed with respect to the grinding time and a high precision of the grinding, as compared with Comparative Example 3 (commercially available). It can be seen that an object to be ground is obtained.

FIG. 6A is a photomicrograph showing the structure of an example of the superabrasive grindstone of the present invention. This superabrasive grindstone uses diamond having a particle size of 0.5 μm to 2 μm as a superabrasive, and a particle size of 0.39 μm to 0.52 as a binder.
It was fired at 1260 ° C. and 20 MPa using W particles of μm. From this figure, it can be seen that the diamond superabrasive grains are uniformly dispersed in the binder structure.

FIG. 6B is a photomicrograph showing the structure of an example of a superabrasive grindstone having a bulk density outside the range of the present invention. This superabrasive grindstone has a particle size of 6 μm
A diamond having a particle diameter of 5 μm and a bulk density of 3.8 g / cm ³ was used as a binder, using diamond of 12 μm and a bulk density of 1.8 g / cm ^3.
(2.1 times that of diamond) Co particles, and 780
It was fired at 10 ° C. and 10 ° C. In this figure, the rubbing pattern portion indicates a portion where no diamond abrasive grains exist. When the binder has a bulk density of more than twice that of the superabrasive grains, the distribution of the superabrasive grains tends to be nonuniform, and the cutting force of the grindstone is not maintained.

The superabrasive grindstone of the present invention can be advantageously used for grinding and cutting superhard materials such as ceramics in the form of a cup grindstone or a thin blade grindstone. FIG. 7A shows a state in which a carbide grinding material S such as, for example, Al ₂ O ₃ .TiC ceramics is ground using the cup grinding wheel 30 of the present invention. FIG. 7 (b) shows a state in which a material S to be ground, such as Al ₂ O ₃ .TiC ceramics, is cut using the thin blade grindstone 31 of the present invention.

The superabrasive grindstone of the present invention is particularly suitable for Al ₂ O ₃ .T
It can be advantageously used, for example, when manufacturing a head chip of a magnetic head from an iC ceramics substrate. One example of a method of manufacturing this head chip will be described with reference to FIGS. As shown in FIG. 8A, first, Al ₂ O ₃ .Ti
A magnetic head element 44 including a core 41, a coil 42, and a lead terminal 43 is formed on a C ceramics substrate 40 by plating, sputtering, or the like. Next, a wafer-like Al ₂ O ₃ .TiC ceramics substrate 40 formed with a number of the magnetic head elements 44... Formed in parallel is placed along the lines 45 on both sides of the parallel magnetic head elements 44. It cuts using the diamond thin blade of the invention.
As a result, as shown in FIG. 8B, a rod 47 having a cross section 46 serving as a slide rail (46) of the magnetic head is obtained. Next, a slide surface 48 is vertically formed on the cross section 46 using the diamond cup grindstone of the present invention.
Grind the groove that will be. Thereby, the slide rail 46
Is formed. Next, when the rod-shaped body 47 is vertically cut for each magnetic head element 44 using the diamond thin blade grindstone of the present invention, as shown in FIG.
A head chip 50 having the slide rails 4, the slide rails 46, and the slide surfaces 48 can be manufactured.

In manufacturing the head chip 50, since the thin blade grindstone and the cup grindstone of the present invention are used, the finished surface of grinding and cutting is extremely smooth.
In addition, since the durability of the grindstone is high, the number of times of sharpening is reduced, and a high-quality head chip can be manufactured with high production efficiency.

[0061]

According to the present invention, the superabrasive grindstone of the present invention has an average particle size of 0.1.
It is made of a sintered body of superabrasive grains made of diamond or cubic boron nitride having a diameter in the range of 5 μm to 60 μm and binder particles, and the binder particles are 0.5 to 0.5 times the superabrasive grains.
Since it has a bulk density in the range of 2 times and a coefficient of thermal expansion in the range of 0.3 to 3 times that of the superabrasive, both the grinding efficiency and the mechanical strength are high, and Efficiency can be maintained uniformly to the end.

The method for producing a superabrasive grindstone of the present invention comprises: a superabrasive made of diamond or cubic boron nitride having an average particle size in the range of 0.5 μm to 60 μm; The bulk density in the range of 2 times to 2 times and 0.
Binder particles having a coefficient of thermal expansion in the range of 3 to 3 times are mixed, and the resulting powder mixture is mixed with 0.5 Tm (Tm
Is the melting point or liquid phase formation temperature of the binder expressed by the absolute temperature ゜ K) or less, so that super abrasive grains having high mechanical strength while maintaining high grinding efficiency uniformly A whetstone is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an embodiment of a superabrasive grindstone of the present invention.

FIG. 2 is a sectional view showing an example of a spark plasma sintering apparatus.

FIG. 3 is a graph showing a relationship between a grinding pressure and a grinding amount of a body to be ground in a grindstone sample of an example and a comparative example.

FIG. 4 is a graph showing the relationship between the grinding time and the amount of grinding of the object to be ground in the grindstone samples of the example and the comparative example.

FIG. 5 is a graph showing the relationship between the grinding time and the rate of change of the grinding speed in the grindstone samples of the example and the comparative example.

FIG. 6 (a) is an embodiment of a superabrasive grindstone of the present invention,
(B) is a micrograph of the structure of an example of a conventional superabrasive grindstone.

FIGS. 7A and 7B are perspective views respectively showing examples of different use forms of the superabrasive grindstone of the present invention.

FIGS. 8A, 8B, and 8C are perspective views showing steps of manufacturing a head chip of a magnetic head as one application example of the superabrasive grindstone of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Super-abrasive grain 2 ... Binder material 3 ... Sintered surface 4 ... Pores 5 ... Pocket 10 ... Super-abrasive grain grindstone 21 ... Die 22 ... Core 23 ... Upper punch 24 ... Lower punch 25 ... Powder Body mixture 26 ... thermocouple

Claims (6)

[Claims] 1. A sintered body of superabrasive grains made of diamond or cubic boron nitride having an average particle diameter in a range of 0.5 μm to 60 μm and binder particles, and the binder particles are A superabrasive having a bulk density in the range of 0.5 to 2 times the abrasive grains and a coefficient of thermal expansion in the range of 0.3 to 3 times the superabrasives. Grain stone. 2. The method according to claim 1, wherein the binder is W, Zr, Cr, M.
Elemental elements consisting of o, Ta and V, W and Si
Carbides, oxides of Ti, Si, and W, and S
2. The superabrasive grinding wheel according to claim 1, wherein the whetstone is at least one member selected from the group consisting of nitrides of i. 3. A superabrasive made of diamond or cubic boron nitride having an average particle size in a range of 0.5 μm to 60 μm, and a bulk density in a range of 0.5 to 2 times the superabrasive. And binder particles having a coefficient of thermal expansion in the range of 0.3 to 3 times the superabrasive grains, and the resulting powder mixture is mixed with 0.5 Tm (Tm is an absolute temperature ΔK Sintering at a temperature below the melting point of the binder or the liquid phase formation temperature). 4. The mixing of the superabrasive grains and the binder particles,
The method for producing a superabrasive grindstone according to claim 3, wherein the method is performed in the presence of a volatile organic solvent and then dried to obtain a powder mixture. 5. The method according to claim 3, wherein the sintering is performed using a spark plasma sintering method or a hot isostatic press sintering method. 6. The method according to claim 3, wherein the sintering is performed under a pressure in a range of 5 MPa to 50 MPa.