JP3406163B2 - Superabrasive stone and its manufacturing method - Google Patents

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 high grinding performance and excellent physical strength and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, structural ceramics such as Si ₃ N ₄ , alumina, zirconia, and Al ₂ O ₃ .TiC ceramics, which are difficult to grind, have been widely used. The reduction of processing cost, which accounts for the weight, has become a major issue.

Conventionally, for the precision machining of these difficult-to-grind materials, a grindstone using so-called "super-abrasive grains" having high hardness such as diamond or cubic boron nitride (hereinafter referred to as "cBN") as abrasive grains has been used. Used, the material of the work piece,
Depending on various requirements such as size, shape, allowance, processing efficiency, processing accuracy, and processing quality, the processing method and grinding machine are determined, and at the same time, the most effective shape, size, and specification of the grindstone are determined.

A grindstone containing superabrasive grains is called a "superabrasive grain grindstone" and is generally constituted by holding the superabrasive grains by a binding material. Depending on the type of the binding material, for example, a synthetic resin is used as the binding material. There are several types, such as the resin bond grindstone, the vitrified bond grindstone using glass, and the metal bond grindstone using metal. Conventionally, the above-mentioned metal bond grindstone has been used as a thin blade grindstone used for precision cutting of ceramics, which is a difficult-to-grind material, from the viewpoint of mechanical strength of the grindstone.

This metal bond grindstone is a soft metal such as bronze or nickel as a binder or cast iron (Japanese Patent Laid-Open No. 3-2.
No. 64263) and a sintering method or an electroforming method. The metal bond grindstone thus obtained has a high mechanical strength of the grindstone itself because the structure of the bonding material is dense, and also has a high holding force for the abrasive grains by the bonding material which is particularly required for grinding difficult-to-grind materials. There is little deformation of the whetstone during grinding,
It has advantages such as good finishing accuracy.

[0006]

However, in the above-mentioned metal bond grindstone, since the bond material structure is dense and hard to wear, a phenomenon in which new cutting edges of abrasive grains constantly appear on the grinding surface of the grindstone,
The so-called "self-developing blade action" is small, it is easily clogged, and high grinding resistance makes it difficult to perform high-efficiency processing, and there are drawbacks such as poor dressing (dressing) properties.

The present invention has been made to solve these problems. Therefore, the object of the present invention is that both grinding efficiency and mechanical strength are excellent, and that it can be suitably used for precision processing of difficult-to-grind materials. An object of the present invention is to provide a superabrasive grindstone that can be used and a manufacturing method thereof.

[0008]

As a means for solving the above problems, the present invention is directed to the firing of superabrasive grains made of diamond or cBN and binder particles having an average grain size in the range of 0.5 μm to 60 μm. It consists of aggregates, and these binder particles
Ri Do oxide film is formed melting point 2000 ° C. or more metal particles to the surface, the metals, W, Os, Ta, I
One or more selected from the group consisting of r, Mo, and Ru
To provide a superabrasive grindstone. Also, the structure of the sintered body
A large number of pores are contained inside, and the porosity is in the range of 5 to 60%.
Preferably there is. Furthermore, the thickness of the oxide film is
It is preferably in the range of 0.05 μm to 0.5 μm.
Yes.

The present invention also has an average particle size of 0.5 μm to 6 μm.
Superabrasive grains consisting of diamond or cBN in the range of 0 μm, and a melting point of 200 with an oxide film formed on the surface.
W, Os, Ta, Ir, Mo, and Ru above 0 ° C
Provided is a method for producing a superabrasive grindstone, which includes a step of mixing binder particles made of particles of one or more kinds of metals selected from the group consisting of the following, and sintering the obtained powder mixture. The above-mentioned sintering is preferably performed by using a discharge plasma sintering method or a hot isostatic press sintering method. The sintering is preferably performed in an atmosphere of an inert gas or oxygen partial pressure of 0.01 MPa or less. Also , absolute Tm
If the melting point of the binder expressed by the temperature K or the liquidus formation temperature is used,
It is preferable to carry out the above-mentioned sintering while maintaining the sintering temperature of 0.5 Tm or less for a time of 30 minutes or less. Further, it is preferable that the mixing ratio of the superabrasive grains and the binder particles is a volume ratio, and the superabrasive grains: the binder particles = 1: 0.5 to 1: 3. Further, it is preferable to perform the above-mentioned sintering at a sintering temperature in the range of 600 ° C to 1500 ° C.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below 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 binder particles 2 are composed of a metal having a melting point of 2000 ° C. or higher, for example, W particles 4 having an oxide film 3 formed on the surface thereof. The average grain size of the superabrasive grains 1 is 0.5 μm to 60 μm.
It is within the range of μm.

The superabrasive grindstone 10 can be manufactured, for example, by the following method. That is, a binder composed of superabrasive grains 1 made of diamond or cBN having an average grain size in the range of 0.5 μm to 60 μm, and metal grains 4 having a melting point of 2000 ° C. or higher and having an oxide film 3 formed on the surface thereof. The powder mixture obtained by mixing the particles 2 with each other is subjected to, for example, a spark plasma sintering method (hereinafter referred to as “SPS method”) or a hot isostatic pressing method (hereinafter referred to as “HIS”).
P method ”).

Since the obtained superabrasive grindstone 10 uses fine diamond particles or cBN particles having an average particle diameter of 0.5 μm to 60 μm as abrasive grains, it grinds difficult-to-grind materials such as ceramics precisely. be able to.

As the binder, hard and brittle metal particles having a high melting point of 2000 ° C. or higher such as W are used.
The refractory metal particles have a strong bonding force with the superabrasive grains 1 when sintered, and the sintered structure formed by fusion bonding the binder particles has an appropriate degree of collapse. When this super abrasive grain grindstone is used for grinding, the physical strength of the grindstone itself is high, while holding the abrasive grain strongly, the dressing (dressing) property is good, clogging is less likely, and there is a self-developing blade action. The grinding resistance is small and efficient grinding is possible.

However, at the time of manufacturing the superabrasive grain grindstone, at least 0.6 T is required to strongly fuse the superabrasive grains 1 and the above-mentioned high melting point metal particles or the high melting point metal particles.
It must be heated to a temperature above m. This temperature is
For example, when W (melting point 3655 ° K) is used as the binder, the temperature is about 1900 ° C or higher. However, it was found that at this sintering temperature, the superabrasive grains 1 themselves deteriorate due to the high temperature and the grinding force decreases, and the desired grinding performance cannot be sufficiently exhibited.

Therefore, as a result of earnest research, the present inventors have found that
When the oxide coating 3 is formed on the surface of the refractory metal particles 4,
The melting point of the oxide coating 3 is significantly lower than the melting point of the metal itself such that the melting point of tungsten trioxide WO ₃ which is an oxide of W is 1400 ° C. 0.5 Tm or less, which is a standard, for example 150
It was found that the super-abrasive grains 1, the binder particles 2, and the binder particles 2 are fused to each other on their surfaces by heating at about 0 ° C., and a strong sintered structure can be formed, and the present invention was reached. .

In the above sintered structure, the oxide film 3
Are formed only on the surface of the binder particles 2, the particles are fused to each other only in the coating layer on this surface, and the hard and brittle property of the binder metal particles 4 itself is not lost. Therefore, the superabrasive grain grindstone 10 of the present invention does not impair the sharpness of the superabrasive grains 1 by high-temperature sintering, has good dressing properties, is less likely to be clogged, has a self-developing blade action, and has a small grinding resistance, It becomes an efficient precision grinding wheel.

Next, various elements constituting the superabrasive grindstone of the present invention will be described in detail. The superabrasive grains used in the superabrasive grain grindstone of the present invention are diamond or cBN. For example, when finely processing a hard workpiece such as a ceramic material, it is preferable to use diamond having the highest hardness. The diamond may be single crystal or polycrystal, and both natural diamond and artificial diamond can be used.

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

The average grain size of the superabrasive grains is 0.5 μm to 60 μm.
Within the range of m. If the average particle size is less than 0.5 μm, the particles are too fine and the grinding ability is not sufficiently expressed.
If it exceeds, for example, when this grindstone is used for fine grinding or lapping, the surface to be ground becomes rough and unsuitable. From this viewpoint, the average grain size of superabrasive grains is 0.5
The thickness is preferably in the range of μm to 10 μm.

The metal used as the binder has a melting point of 2
Any material may be used as long as it has a temperature of 000 ° C. or higher and can form an oxide film on the surface of the particles, and the oxide film can be melted at a temperature that does not deteriorate the superabrasive grains.
Preferred metals are those selected from the group consisting of W, Os, Ta, Ir, Mo, and Ru. Table 1 shows the hardness (Hv), melting point (° C), oxide composition, and oxide melting point (° C) of the above preferable metals. Of these, W is the most preferable metal because it has the highest melting point.

[0021]

[Table 1]

The particle size of the binder particles is not particularly limited, but is preferably in the range of 5% to 50% of the average particle size of the superabrasive particles. When the particle size of the binder particles with respect to the superabrasive grains exceeds 50%, the contact area between the superabrasive grains and the binder particles becomes small in the state where the mixture is filled in the mold during sintering, and The strength of the grindstone itself decreases due to lack of binding force. On the other hand, if it is less than 5%, the contact area is sufficiently large so that the bonding force at the time of sintering is not a problem, but the porosity and the pore diameter are small, and the sintered product is not much different from the non-porous metal bond grindstone.

Since the superabrasive grindstone of the present invention is formed by the surface sintering of powder, as shown in FIG. 1, a large number of pores 5 are included in its structure and it is porous. . The porosity is preferably within the range of 5% to 60%. When the porosity is less than 5%, the structure of the binding material becomes dense and is not easily worn away, so that the spontaneous blade action is less likely to occur, and a pocket for storing chips generated during grinding (reference numeral 6 in FIG. 1). ) Is insufficient, and the circulation of the cooling liquid is insufficient, so that clogging and melting due to frictional heat are likely to occur. When the porosity exceeds 60%, the physical properties of the grindstone itself are deteriorated, and spillage and crushing are likely to occur. From these viewpoints, the porosity is more preferably within the range of 5% to 45%. The porosity is the particle size of each of the superabrasive grains and the binder particles, the mixing ratio, the pressure applied during sintering,
It can be adjusted by selecting various conditions such as the presence or absence of volatile inclusions during mixing.

In producing the superabrasive grindstone of the present invention, high melting point metal particles having the oxide coating 3 formed on the surface thereof are prepared in advance. To form an oxide film on the surface of refractory metal particles, the refractory metal particles are left to stand in the air for natural oxidation, forced oxidation such as heating in an oxygen atmosphere, or refractory metal particles are formed. There are methods such as applying the oxide, and any of these methods may be used.

Next, the superabrasive grains and the binder particles are uniformly mixed. The mixing ratio of the superabrasive grains and the binder is preferably in the range of 1: 0.5 to 1: 3 in terms of the volume ratio of superabrasive grains to binder particles. When the ratio of the binder is less than 1: 0.5, the density of the superabrasive grains is too high, the strength of the sintered body decreases, and the grindstone becomes brittle. If the ratio of the binder is more than 1: 3, the grinding ability is reduced.

When mixing the superabrasive grains and the binder, for example, a volatile liquid such as ethanol is added and dispersed in the liquid by a ball mill or the like, and then the liquid component is removed by vacuum drying or the like to remove the superabrasive grains. It is preferred to obtain a powder mixture of and binder particles. According to this method, agglomeration of the superabrasive grains is prevented, and not only a powder mixture in which the superabrasive grains are uniformly dispersed in the binder is obtained, but also blunting of the cutting edge and heat generation due to powder friction during mixing. Deterioration due to is prevented.

Sintering is preferably performed using the SPS method or the HIP method. These are all powder sintering methods. 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 The binding force of is strengthened.

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

A powder mixture 25 of superabrasive grains and a binder is filled in a predetermined amount in the gap between the die 21 and the core 22 formed into a predetermined grindstone 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 are compressed at a predetermined pressure from above and below, and then a pulse 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 energizing current, and the temperature control and the sintering time control are strictly performed. It can be carried out. Examples of the SPS device that can be used in the above SPS method include a model SPS-2050 type spark plasma sintering device manufactured by Sumitomo Coal Mining Co., Ltd.

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

In any of the sintering methods, the sintering is preferably performed in an atmosphere of an inert gas or oxygen partial pressure of 0.01 MPa or less. When sintering is performed by applying heat and pressure in an atmosphere where the oxygen partial pressure exceeds 0.01 MPa, the superabrasive grains are altered and the oxide film on the surface of the binder increases and the binder is a refractory metal. This is because there is a risk that the profit of As the inert gas, N ₂ or Ar is preferably used.

Upon sintering, the sintering temperature is preferably 0.5 Tm or less. Here, Tm is the absolute temperature K
Is the melting point of the binder metal or the liquidus formation temperature. By setting the sintering temperature to 0.5 Tm or less, as described above, the binder particles fuse with each other only by the oxide film, and while maintaining the strength of the grindstone itself, it has a proper collapse property and spontaneously generates. It exhibits a blade action and maintains good grindability.

The lower limit of the sintering temperature depends on the properties of the binder used and the sintering pressure, but is set to a temperature at which at least the particles are surface-fused to each other to form a fused phase. This lower limit temperature is usually 600 ° C. or higher. From this viewpoint, the practically preferable sintering temperature range is 600 ° C. to 1500 ° C.
Within the range of ° C.

Further, it is preferable that the time of holding the above-mentioned sintering temperature during the sintering is within 30 minutes. This is because if the temperature at which the liquid phase is generated is maintained for more than 30 minutes, the amount of superabrasive grains is significantly reduced. From this viewpoint, the SPS method capable of strictly controlling the sintering temperature and the sintering time is a method suitable for producing the superabrasive grains of the present invention.

(Example 1) Average particle diameter of 25 μ as superabrasive grains
m diamond was used, and W having a particle size of 1 μm to 2 μm with an oxide film formed on the surface was used as a binder, and the volume ratio of superabrasive grains to the binder was 25:32. The oxide film on the surface of the W particles has a W particle content of 1 at 800 ° C in the atmosphere.
After heating for an hour, it was naturally cooled and formed. At this time, the thickness of the oxide film was 0.05 μm to 0.5 μm.

Ethanol was added to the above mixture to prepare a slurry, which was then charged into a ball mill and dispersed by a liquid dispersion method. After completion, ethanol was removed under reduced pressure to make the superabrasive grains uniform in the binder. A powder mixture dispersed in was obtained.

The obtained powder mixture was used for the SPS shown in FIG.
Sintered using the equipment. The die 21 is made of graphite and has an inner diameter of 92 mm, and the core 22 has an outer diameter of 40 mm.
Met. The space between the die 21 and the core 22 was filled with 14.7 g of the powder mixture, and the atmosphere of the die was changed to O ₂
The upper punch 2 is replaced with a gas having a partial pressure of 0.01 MPa or less.
3 and lower punch 24 to drive powder mixture 25 to 2
A pressure of 0 MPa was applied, a pulse current was applied between both punches, and heating was performed at 1260 ° C. for 5 minutes.

The obtained superabrasive grindstone of the embodiment has an outer diameter of 92
mm, inner diameter 40 mm, thickness 0.429 mm, thin blade grindstone, weight 14.6644 g, porosity 42.2% by volume.

Comparative Example 1 The same superabrasive grains as in Example 1 were used, Co having a grain size of 5 μm was used as the binder, and the volume ratio of superabrasive grains to the binder was 25:32. Was mixed by a liquid dispersion method and dried under reduced pressure to obtain a powder mixture.

The obtained powder mixture was sintered in the same manner as in Example 1 except that the sintering temperature was 780 ° C. using the same die and SPS apparatus as in Example 1, and the grindstone of Comparative Example 1 was used. Obtained. This product has a thickness of 0.327 mm and a weight of 7.76.
18 g, the porosity was 23.6% by volume.

A grinding test was carried out using the superabrasive grindstones of Example 1 and Comparative Example 1. For the grinding test, a wet constant pressure grinding method was used that was not affected by the Young's modulus of the grindstone, the rigidity of the grinder, or the horsepower. As the object to be ground, Al ₂ O ₃ · T
iC ceramics (bending strength 588 MPa, micro Vickers hardness 19 GPa) was used.

For comparison, a commercially available electroformed metal-bonded superabrasive grindstone having the same shape was used as Comparative Example 2. FIG. 3 shows the relationship between the grinding pressure (MPa) measured for the superabrasive grindstones of Example 1, Comparative Example 1 and Comparative Example 2 and the grinding amount (mm ³ ) after grinding for 30 seconds at each grinding pressure. .

As a result of the test, the electroformed metal bond of Comparative Example 2
The superabrasive grindstone can prevent clogging at a grinding pressure of about 0.9 MPa.
Therefore, it became impossible to grind. Grinding amount at this pressure limit is about 2
mm ³Met. Super Abrasive Grain Stone of Co Bonding Material of Comparative Example 1
Was broken at a grinding pressure of about 1.25 MPa. This pressure limit
The grinding amount at the time of the world is about 4.5 mm³Met.

On the other hand, the superabrasive grindstone of Example 1 is
The grinding performance was still normal at a grinding pressure of about 2 MPa, and a grinding amount of about 6 mm ³ was shown at a grinding pressure of about 2 MPa. From these results, the superabrasive grindstone of Example 1 has a higher porosity than that of Comparative Example 1, but has excellent physical properties, is not destroyed even if the grinding pressure is increased, and is almost proportional to the grinding pressure. It can be seen that the grinding amount increased.

Example 2 According to the method of Example 1, diamond having a grain size shown in Table 2 was used as the superabrasive grain, and an oxide film was formed on the surface as a binder.
Using W of μm, the diameter is 30 according to the manufacturing conditions shown in Table 2.
A grindstone sample having a thickness of 0.5 mm was prepared. The porosity, Young's modulus, and Vickers hardness of this product were measured.
The results are shown in Table 2.

(Comparative Example 2) In accordance with the method of Example 2, diamond having a grain size shown in Table 2 was used as superabrasive grains, Co having a grain size shown in Table 2 was used as a binder, and shown in Table 2. A grindstone sample having the same shape as that of Example 2 was prepared according to the manufacturing conditions. The porosity, Young's modulus, and Vickers hardness of this product are shown in Table 2 together with Example 2.

[0048]

[Table 2]

From the comparison between Example 2 and Comparative Example 2, the superabrasive grindstone of the present invention has a higher porosity than the conventional superabrasive grindstone using Co as the binding material, and has physical properties. Also proves to be excellent.

(Example 3) According to the method of Example 1, diamond having a grain size shown in Table 3 was used as the superabrasive grain, and an oxide film was formed on the surface as a binder.
Using W of μm, the outer diameter 92 depending on the manufacturing conditions shown in Table 3.
mm, an inner diameter of 40 mm, and a thickness of 0.4 mm, a thin blade grindstone sample was prepared. The porosity, Young's modulus, and Vickers hardness of this product were measured. The results are shown in Table 3.

(Comparative Example 3) In accordance with the method of Example 2, diamond having a grain size shown in Table 3 was used as the superabrasive grain, Co having a grain size shown in Table 3 was used as the binder, and shown in Table 3. A grindstone sample having the same shape as that of Example 3 was prepared according to the manufacturing conditions. The porosity, Young's modulus, and Vickers hardness of this product are shown in Table 3 together with Example 3.

[0052]

[Table 3]

From the comparison between Example 3 and Comparative Example 3, the superabrasive grindstone of the present invention has a higher porosity than the conventional superabrasive grindstone using Co as a binding material, and has physical properties. Also proves to be excellent.

In the superabrasive grindstone of the present invention, it is important that an oxide film is formed on the surface of the binder particles. W having a particle diameter of 1 μm to 2 μm was used as the binder particles, and those with and without the oxide film formed were treated under the conditions of temperature 1260 ° C., pressure 10 MPa, and time 5 minutes, and sintering was possible under these conditions. The amount of oxygen contained in the sintered body and that which could not be sintered was measured by Auger analysis.
The measurement results of those that could be sintered are shown in FIGS. 4A and 4B, and the measurement results of those that could not be sintered are shown in FIGS. 5A and 5B. Here, in FIG. 4A, the carbon content is 38.9.
at%, FIG. 4B shows a carbon content of 7.9 at%, and FIG.
5A shows the case where the carbon content is 32 at%, and FIG. 5B shows the case where the carbon content is 3.2 at%.

That is, regardless of the carbon content in the sample, the oxygen content is as high as 3.2 at% to 6.7 at%.
The samples (a) and (b) could be sintered at 1260 ° C., while the oxygen content was 1.3 at% to 1.9 at.
The samples of FIGS. 5 (a) (b), which are as low as%, could not be sintered at the same temperature. It is clear that the oxygen formed an oxide film on the surface of the binder particles, thereby lowering the sintering temperature of the binder particles and enabling the sintering.

The superabrasive grindstone of the present invention can be advantageously used in the shape of a cup grindstone or a thin blade grindstone for grinding and cutting a superhard material such as ceramics. FIG. 6 (a) shows a state in which a cemented carbide workpiece S such as Al ₂ O ₃ .TiC ceramics is being ground using the cup grindstone 30 of the present invention. FIG. 6B shows a state in which a cemented carbide workpiece S 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 when manufacturing a head chip of a magnetic head from an iC ceramic substrate. An example of a method of manufacturing this head chip will be described with reference to FIGS. As shown in FIG. 7A, first, Al ₂ O ₃ .Ti
A magnetic head element 44 including a core 41, a coil 42, and a connection pad 43 is formed on a C ceramics substrate 40 by a thin film method. Next, the wafer-shaped Al ₂ O ₃ .TiC ceramics substrate 40 formed with a large number of the magnetic head elements 44 ...
Along the lines 45, 45 on both sides of, the diamond thin blade grindstone of the present invention is used for cutting. As a result, FIG.
As shown in (1), a rod-shaped body 47 having a cross section 46 to be the slide rail (46) of the magnetic head is obtained. Next, in this cross section 46, a groove to be the slide surface 48 is ground in the vertical direction using the diamond cup grindstone of the present invention. As a result, the slide rail 46 is formed. Next, if 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. 7C, the magnetic head element 44, the slide rail 46, and the slide surface 48. It is possible to manufacture the head chip 50 having

Since the thin blade grindstone and the cup grindstone of the present invention are used in the manufacture of the head chip 50, the finished surface for grinding and cutting is extremely smooth.
Further, since the grindstone has high durability, the number of times of sharpening is reduced, and high quality head chips can be manufactured with high production efficiency.

[0059]

The superabrasive grain grindstone of the present invention comprises a sintered body of superabrasive grains and binder particles, and the binder particles are made of a metal having a melting point of 2000 ° C. or higher with an oxide film formed on the surface. Since it is composed of particles of No. 3, it can be sintered at a relatively low temperature, and the binding force between the superabrasive grains and the binder particles is strong and the strength of the grindstone itself is high. Furthermore, the sintered structure has an appropriate degree of collapse, has good dressing properties while strongly holding the abrasive grains, does not easily clog, has a self-developing blade action, has a small grinding resistance, It can be ground efficiently and efficiently.

[Brief description of drawings]

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

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

FIG. 3 is a graph showing a relationship between a grinding pressure and a grinding amount of an example and a comparative example.

4A and 4B are Auger analysis graphs for measuring oxygen content in a sintered composition.

5 (a) and 5 (b) are Auger analysis graphs for measuring oxygen content in a sintered composition, respectively.

6 (a) and 6 (b) are perspective views showing examples of different usage forms of the superabrasive grindstone of the present invention.

7 (a), (b) and (c) are perspective views showing a process of manufacturing a head chip of a magnetic head which is an application example of the superabrasive grindstone of the present invention.

[Explanation of symbols]

1 ... Super abrasive grain 2 ... Binder particles 3 ... Oxide film 4 ... Metal particles 5 ... pores 6 ... Pocket 10 ... Super abrasive grain whetstone 21 ... Die 22 ... Nakako 23 ... Upper punch 24 ... Lower punch 25 ... Powder mixture 26 ... Thermocouple

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-67740 (JP, A) JP-B 48-10922 (JP, B1) JP-B 53-41833 (JP, B1) (58) Field (Int.Cl. ⁷ , DB name) B24D 3/06 B24D 3/00 320 B24D 3/02

Claims (8)

(57) [Claims] 1. A sintered body of super-abrasive grains composed of diamond or cubic boron nitride and having an average particle diameter in the range of 0.5 μm to 60 μm, and binder particles, the binder particles being on the surface. It is composed of particles of a metal having an oxide film and a melting point of 2000 ° C. or higher, and the metal is W, Os, or T.
1 selected from the group consisting of a, Ir, Mo, and Ru
A superabrasive whetstone characterized by being more than one kind. 2. The superabrasive grindstone according to claim 1, wherein a large number of pores are included in the structure of the sintered body, and the porosity is in the range of 5 to 60%. 3. The average particle size is in the range of 0.5 μm to 60 μm.
Consisting of diamond or cubic boron nitride
Super-abrasive grains and melting point 2000 with oxide film formed on the surface
From W, Os, Ta, Ir, Mo, and Ru above ℃
A bond consisting of particles of one or more metals selected from the group
Mixing with material particles and sintering the resulting powder mixture
And a method for manufacturing a superabrasive whetstone . 4. The spark plasma sintering method or the sintering
Using the hot isostatic press sintering method
The method for producing a superabrasive grindstone according to claim 3, wherein 5. The sintering is performed by using an inert gas or oxygen content.
The method for producing a superabrasive grindstone according to claim 3 , wherein the pressure is 0.01 MPa or less . 6. The melting point of the binder, which represents Tm in absolute temperature K.
Or at the liquidus formation temperature, the above sintering was performed at 0.5 Tm.
The method for producing a superabrasive grindstone according to claim 3 , wherein the sintering is carried out by holding the sintering temperature for 30 minutes or less . 7. The mixing ratio of superabrasive grains and binder particles is the volume ratio.
Then, in the range of superabrasive grains: binder particles = 1: 0.5 to 1: 3
It exists , The manufacturing method of the superabrasive grain grindstone of Claim 3 characterized by the above-mentioned. 8. The sintering is performed at 600 ° C. to 1500 ° C.
The method for manufacturing a superabrasive grindstone according to claim 3 , wherein the method is performed at a sintering temperature within the range .