JP3380125B2 - Porous superabrasive stone and its manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates generally relates to porous superabrasive grinding wheel used in the precision machining field, porous <br/> superabrasive physical strength was also excellent with sustained particularly high grinding efficiency A grain grindstone and a manufacturing method thereof.

[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, are often used, and there is 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, grinding is required for imparting shape and dimensioning in the final manufacturing process. For precision machining of difficult-to-grind materials such as these ceramic materials, grindstones containing so-called "superabrasive grains" such as diamond and cubic boron nitride (hereinafter referred to as "cBN") are used as abrasive grains.

A grindstone containing the superabrasive grains is called a "superabrasive grain grindstone" and is generally manufactured by bonding the superabrasive grains with a bonding material and molding. As the bonding material, a resin-bonded grindstone made of synthetic resin, a vitrified bond grindstone made of glass, and a metal bond grindstone made of metal are used according to the characteristics of the object to be ground. .

In recent years, as represented by an integrated circuit using a thin film process, the density of devices has been increased and the devices have become widespread.
For example, fine cutting such as 0.3 mm or less has been required, and a grinding blade with a thin blade capable of this cutting has been demanded.

Conventionally, as a thin blade grindstone used for precision grinding of hard-to-grind ceramics, a non-porous metal bond grindstone having high rigidity has been used from the viewpoint of mechanical strength of the grindstone. The metal bond grindstone is generally formed by an electroforming method or a sintering method in which abrasive grains are uniformly dispersed in a binder. As the binder, for example, Cu-Sn
Bronze-based soft metals such as Cu-Sn-Co-based and Cu-Sn-Fe-Co-based are used.

Since these conventional metal-bonded grindstones are non-porous, the mechanical strength of the grindstone itself is remarkably higher than that of other vitrified bond grindstones or resin-bonded grindstones, and is particularly important when grinding difficult-to-grind materials. Although the holding power of the abrasive grain by the bonding material is also excellent, the phenomenon that the new cutting edge of the abrasive particle constantly appears on the surface of the grindstone because the bonding material structure is dense and it is difficult to wear, the so-called "self-made blade action" is small Also, since there are no pores that help the discharge of chips generated during grinding, there are problems such as easy clogging, increased grinding resistance, so-called "cutting", and difficulty in high-efficiency processing of the workpiece. there were.

[0007]

To solve these problems, a grindstone using cast iron as a binder has been proposed (see Japanese Patent Laid-Open No. 3-264263). This cast iron bond grindstone has high rigidity, and since the bond material structure does not cause plastic flow and causes brittle fracture, it has many advantages such as less clogging, but its strength is too high and dressing (dressing) properties are high. There was a problem that was bad.
Further, fine cast iron powder is generally difficult to obtain and expensive.

A porous metal bond grindstone has been proposed as a means for improving the drawbacks of the cast iron bond grindstone (see Japanese Patent Laid-Open No. 7-251379). This porous metal-bonded grindstone uses metal powder as a binder, and super-abrasive grains that are abrasive grains are dispersed and held in the porous structure of the binder formed by powder sintering. By adjusting, the mechanical strength of the grindstone and / or the holding force of the abrasive grains can be controlled. This grindstone is an excellent grindstone because it does not cause clogging, can be continuously ground for a long time, has excellent dressing properties, and has a high grinding ratio.
Since the grindstone itself has low rigidity because it has pores, it has been difficult to manufacture a grindstone that requires high rigidity such as a thin blade grindstone.

The above-described porous metal bond grindstone for precision processing is manufactured by a powder sintering method in which fine particle powders of abrasive grains and a binder are mixed, put in a mold, and sintered under pressure. At this time, there is also a problem that it is difficult to uniformly disperse the superabrasive grains and the fine grain powder of the binder, and they are easily separated from each other, and it is difficult to obtain a uniform grindstone.

As described above, in the grindstone for precision machining, the grinding performance and the mechanical strength of the grindstone are contradictory factors, and it is difficult to achieve both of them at the same time. Further, in the powder sintering, superabrasive grinding is performed. It was difficult to uniformly mix and disperse the particles and the binder. The present invention was made in order to solve these problems, and therefore, the object thereof is that both grinding efficiency and mechanical strength are high, and superabrasive grains are uniformly mixed and dispersed in a binder, It is an object of the present invention to provide a superabrasive grindstone having a uniform grinding performance and a manufacturing method thereof.

[0011]

As a means for solving the above-mentioned problems, the present invention provides a super-abrasive grain composed of diamond or cubic boron nitride having an average grain size in the range of 0.5 μm to 60 μm and a binder grain. made of sintered body of the binder particles, said a bulk density in the range 0.5 to 2 times of the superabrasive, within the superabrasive 0.3 times to 3 times the all SANYO having a thermal expansion coefficient, W, Zr, Cr, Mo , Ta
And a simple element consisting of V, Ti, Si, and W
Selected from the group consisting of oxides of Si and nitrides of Si
The sintered body has a porosity of 5 while being composed of one or more kinds.
% Or more and 60% or less
A porous superabrasive grindstone is provided.

In the above, the porosity is 28.3% to 50.
It is preferable that the content is within the range of 8%.

The present invention also has an average particle size of 0.5 μm to 6 μm.
Superabrasive grains composed of diamond or cubic boron nitride within a range of 0 μm, a bulk density within a range of 0.5 times to 2 times that of the superabrasive grains, and 0.3 times to 3 times of the superabrasive grains. And a coefficient of thermal expansion within the range of W, Zr, Cr, Mo, Ta
R, in addition to the elemental element consisting of V, Ti, Si, and W
1 selected from the group consisting of oxides and Si nitrides
One or more kinds of binder particles are mixed, and the obtained powder mixture is sintered at a temperature of 0.5 Tm or less (Tm is the melting point of the binder expressed in absolute temperature K or the liquid phase formation temperature) or lower. When
In both cases, the sintering was performed at a pressure within the range of 5 MPa to 50 MPa.
A method of manufacturing a superabrasive grindstone, which comprises performing the sintering at a sintering temperature in the range of 600 to 1500 ° C., is provided below.

In the above manufacturing method, it is preferable that the superabrasive grains and the binder particles are mixed in the presence of a volatile organic solvent and then dried to obtain a powder mixture. The above-mentioned sintering is preferably performed by using a discharge plasma sintering method (hereinafter referred to as “SPS method”) or a hot isostatic press sintering method (hereinafter referred to as “HIP method”). In addition, the oxygen partial pressure in the atmosphere during the sintering is 0.0
It is preferably 1 MPa or less.

[0015]

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 grain 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 grain size of the superabrasive grains is in the range of 0.5 μm to 60 μm, and the binder particles 2 are made of, for example, W (tungsten).
Bulk density in the range of 5 times to 2 times, and 0.3 of the superabrasive grain 1
And a coefficient of thermal expansion within the range of 3 to 3 times.

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

Since 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 grains 1, ceramics, cemented carbide, etc. It is possible to precisely grind difficult-to-grind materials.

If the bulk density of the binder particles 2 is within 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. The superabrasive grains 1 and the binder particles 2 can be uniformly dispersed during the mixing during the production. Therefore, the superabrasive grains 1 are uniformly distributed in the whole of the grindstone body after sintering without being unevenly distributed, and uniform cutting ability can be maintained until the grindstone is used up.

The thermal expansion coefficient of the binder particles 2 is, for example, W
(Coefficient of thermal expansion 4.6 × 10 ⁻⁶ ), superabrasive grains 1 (for example, the coefficient of thermal expansion of diamond 3.0 × 10 ⁻⁶ ) of 0.
Within the range of 3 times to 3 times, the particles may be misaligned 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 contraction rate. Internal stress generated at the sintering interface is relieved, fine cracks caused by these, warp of the grindstone, swelling, etc. are prevented,
The physical properties and formability of the superabrasive grindstone are improved.

Next, the various elements constituting the superabrasive grindstone of the present invention will be described in detail. The superabrasive grain 1 used in the superabrasive grain grindstone 10 of the present invention is 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 1 is 0.5 μm to 60 μm.
It is set within the range of μm. 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 m, for example, when this grindstone is used for fine grinding or lapping, the surface to be ground becomes rough and is unsuitable.

As the binder, the coefficient of thermal expansion is within the above range, and the bulk density of the particles is within the above range, and when the hot pressure is applied, the superabrasive grains and the sintered body are formed. Any material that can be used can be used. Examples of preferable binders include simple elements of W, Zr, Cr, Mo, Ta and V, carbides of W and Si, Ti and S.
Examples thereof include oxides of i and W, nitrides of Si, and the like. In particular, W is a suitable bonding material when diamond is used as the superabrasive grains.

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 superabrasive grains (diamonds) and typical binders. Also for reference,
Although it is out of the range as a binder for the superabrasive grindstone of the present invention,
Co and Fe, which are conventionally used binders
Similar data for and are shown in Table 2.

[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 it is generally in the range of 5% to 50% of the average particle size of the superabrasive particles. Is preferred. 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. 5% again
If it is less than 1, the contact area is sufficiently large so that the bonding force at the time of sintering will not be a problem, but the porosity and the pore diameter will be small, and the sintered product will not be much different from the non-porous metal bond grindstone.

In the superabrasive grain grindstone 10 of the present invention, the mixing ratio of the superabrasive grains and the binder is within the range of 1: 0.5 to 1: 3 in terms of volume ratio of superabrasive grains to binder particles. Preferably. When the proportion of the binder is less than 1: 0.5, the density of the superabrasive grains is too high, the strength of the sintered body is lowered, and spillage and the like are likely to occur. If the ratio of the binder is more than 1: 3, the grinding ability becomes insufficient.

Since the superabrasive grindstone 10 of the present invention is formed by the surface sintering of powder particles, as shown in FIG. 1, a large number of pores 4 are contained in its structure and become porous. ing. This porosity is preferably within the range of 5% to 60%. If the porosity is less than 5%, the structure of the binding material becomes dense and is not easily worn away, so that not only the spontaneous blade action is unlikely to occur, but also a pocket for accommodating chips generated during grinding (reference numeral 5 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 can be adjusted by selecting various conditions such as the particle size of each of the superabrasive grains and the binder particles, the mixing ratio, the pressure applied during sintering, the presence or absence of volatile inclusions during mixing.

Next, the method for producing the 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, and then drying the solvent.

As the volatile organic solvent, any of hydrocarbons, alcohols, esters, ethers and the like can be used. Especially, from the viewpoint of easiness of volatilization and cost.
Preference is given to using ethanol or methanol.
The presence of the volatile organic solvent improves the lubricity between particles during stirring and mixing, and achieves a more uniform dispersion.
Since the friction between the particles is alleviated, abrasion of the cutting edge of the superabrasive grains and pulverization of the binder are prevented. This volatile organic solvent is evaporated and dried, preferably under reduced pressure, prior to sintering to obtain a powder mixture.

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 carried out by using, for example, a spark 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 used from above and below, preferably 5 MPa to 50 MPa.
It is compressed at a pressure in the range of MPa and then 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 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 particles 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 temperature is 0.5 Tm or less. Here, Tm is the melting point or liquid phase formation temperature of the binder particles expressed in absolute temperature K.
By setting the sintering temperature to 0.5 Tm or less, the binder particles are fused to each other only by the surface layer of the binder particles, exhibiting a proper crushing property while maintaining the strength of the grindstone itself and exhibiting a self-sharpening effect, which is good. Excellent grindability is maintained.

The lower limit of the sintering temperature depends on the characteristics of the binder particles to be used and the sintering pressure, but at least the particles can be 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 15 ° C.
It is set within the range of 00 ° C.

In the powder sintering method, when the sintering is performed in a die, the pressure applied to the powder mixture is 5 MPa to 50 M.
It is preferably within the range of Pa. If the pressure is less than 5 MPa, the porosity of the grindstone that is a sintered product becomes too high,
The mechanical strength of the entire grindstone is significantly reduced. Also the pressure is 5
If it exceeds 0 MPa, the porosity of the grindstone is excessively reduced, and the grindstone becomes almost non-porous, and the grinding efficiency is significantly reduced.

In any of the sintering steps, 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 pressure in an atmosphere in which the oxygen partial pressure exceeds 0.01 MPa, the super-abrasive grains and the binder particles may deteriorate. As an inert gas,
N ₂ or Ar is preferably used.

Next, examples of the present invention will be shown. In all of these examples, the outer diameter is 120 mm, the inner diameter is 114 mm,
It is a superabrasive grindstone formed into 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 obtained slurry mixture was taken out from the ball mill and ethanol was removed by vacuum drying 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 device shown in FIG. 2 and sintered under the following conditions to manufacture a cup-shaped superabrasive grindstone having the above-mentioned dimensions. Sintering temperature: 1260 ° C. Sintering pressure: 20 MPa

When the cross section of the obtained superabrasive grain grindstone of Example 1 was magnified 10000 times with an electron microscope, the diamond superabrasive grains 1 were separated from each other as schematically shown in FIG. The binder particles 2 are evenly distributed in the sintered structure,
The superabrasive grains 1 and the binder 2 particles were fused to each other at the contact surface 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 grindstone of Example 2 was manufactured according to Example 1 with 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 with the following materials and manufacturing conditions. Table 3 shows the porosity and physical properties of the obtained superabrasive grindstone of Example 3.

Example 4 The superabrasive grindstone of Example 3 was manufactured according to Example 1 with 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 in accordance with the composition and manufacturing method shown in Example 1 and the following composition and manufacturing conditions. This comparative example 1
Is an example in which the thermal expansion coefficient of the binder particles falls outside 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 In accordance with 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 outside 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 Comparative Example 3 in the test.

[0050]

[Table 3]

(Grinding Performance Test) A grinding test was conducted on each of the above samples. 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, 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.

In FIG. 3, each grindstone sample was mounted on a grinder, and the cross section of the object to be ground was pressed against the grinding surface of each sample for a predetermined time (30 seconds). The grinding pressure at this time was 0.3MP.
The amount of grinding (mm ³ ) was measured when a, 0.5 MPa, 1 MPa, and 2 MPa were sequentially changed. FIG. 4 shows a similar grinding pressure (1M
Grinding time is 30 seconds, 60 seconds, 120 seconds, 240
The measured grinding amount (mm ³ ) in seconds and 480 seconds. Further, FIG. 5 shows changes in the grinding speed with respect to each grinding time when the grinding speed for 30 seconds from the start of grinding is 100%.

From the results of these physical property tests and grinding performance tests, the following matters become clear. (1) From the results of Table 3, the samples of Examples 1 to 3 were
Since the binder is W and its bulk density is 0.75 to 1.81 times that of the superabrasive grains, it is in the range of 0.5 to 2 times and the coefficient of thermal expansion is that of the superabrasive grains. Since it is 1.53 times, it is in the range of 0.3 to 3 times. These have physical properties, especially Young, as compared with Comparative Example 2 (Fe) having a bulk density of 2.2 times that of superabrasive grains and Comparative Example 1 (Co) having a thermal expansion coefficient of 4.17 times that of superabrasive grains. It is found that the rate and the micro Vickers hardness are excellent. Similarly in Example 4, the bulk density of the binder (Cr) is 0.83 times that of the superabrasive grains, and the thermal expansion coefficient thereof 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 grinding amount for grinding within a certain period of time as compared with each comparative example.
You can see that it is a sharp whetstone. Therefore, the number of steps in the grinding process can be reduced as compared with the conventional case. Further, when the grinding pressure is increased, the grinding amount is correspondingly increased linearly, and it is understood that the grinding stone is easy to control the grinding accuracy. On the other hand, in each of the grindstones of Comparative Examples, the grinding amount does not increase even if the grinding pressure is increased due to the influence of 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 the comparative examples, and is a grindstone having a continuous sharpness. Further, from the results of FIG. 5, the samples of Examples 1 to 3 have a small change in the grinding speed with respect to the grinding time as compared with Comparative Example 3 (commercially available product), and it is easy to keep the grinding accuracy constant. It can be seen that an object to be ground can be obtained.

FIG. 6 (a) is a micrograph showing the structure of an example of the superabrasive grindstone of the present invention. This superabrasive grain grindstone uses diamond with a grain size of 0.5 μm to 2 μm as superabrasive grains, and has a grain size of 0.39 μm to 0.52 as a binder.
It was obtained by using W particles of μm and calcined under the conditions of 1260 ° C. and 20 MPa. From this figure, it can be seen that the diamond superabrasive grains are uniformly dispersed in the bond structure.

FIG. 6 (b) is a micrograph 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 grain size of 6 μm as superabrasive grains.
12 μm, bulk density 1.8 g / cm ³ diamond is used, and the binder has a particle size of 5 μm and bulk density 3.8 g / cm ^3.
780 with Co particles (2.1 times that of diamond)
It was baked under the conditions of ° C and 10 MPa. In this figure, the rubbing pattern-like portions indicate the portions where the diamond abrasive grains do not exist. As described above, when the bulk density of the binder exceeds twice that of the superabrasive grains, the distribution of the superabrasive grains is likely to be non-uniform, and the cutting force of the grindstone does not continue.

The superabrasive grindstone of the present invention can be advantageously used for grinding and cutting a superhard material such as ceramics in the shape of a cup grindstone or a thin blade grindstone. FIG. 7A shows a state in which a cemented carbide workpiece S such as Al ₂ O ₃ .TiC ceramics is ground using the cup grindstone 30 of the present invention. FIG. 7B shows a state in which a cemented carbide work material 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. 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, a sputtering method, or the like. Next, the wafer-shaped Al ₂ O ₃ .TiC ceramics substrate 40 on which a large number of the magnetic head elements 44 are formed in parallel is formed along the lines 45 on both sides of the parallel magnetic head elements 44. Cutting is performed using the thin diamond blade of the invention.
As a result, as shown in FIG. 8B, a rod-shaped body 47 having a cross section 46 to be the slide rail (46) of the magnetic head is obtained. Next, a sliding surface 48 is vertically attached to the cross section 46 by using the diamond cup grindstone of the present invention.
Grind the groove to be. As a result, the slide rail 46
Is formed. Next, when the rod-shaped body 47 is cut vertically into the magnetic head elements 44 by using the diamond thin blade grindstone of the present invention, as shown in FIG.
The head chip 50 having the number 4, the slide rail 46, and the slide surface 48 can be manufactured.

When the head chip 50 is manufactured, since the thin blade grindstone and the cup grindstone of the present invention are used, 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.

[0061]

The porous superabrasive grindstone of the present invention is a sintered body of superabrasive grains made of diamond or cubic boron nitride and having an average grain size in the range of 0.5 μm to 60 μm and binder particles. 0 becomes, the binder particles of the superabrasive.
5 times the bulk density in the range 2 times the state, and are not having a thermal expansion coefficient in the range the superabrasive 0.3 to 3 times of the pre
The binder particles described above are W, Zr, Cr, Mo, Ta and
Oxidation of a simple element consisting of V, Ti, Si, and W
Or more than one selected from the group consisting of silicon nitride and Si nitride
On the other hand, the porosity of the sintered body is 5% or less.
In addition, since it is within the range of 60% or less, both the grinding efficiency and the mechanical strength are high, and the grinding efficiency can be maintained uniformly until the end. Also, the pores
If the rate is within the range of 28.3% to 50.8%,
Excellent in Young's modulus and micro Vickers hardness, and in bending strength
It is possible to reliably obtain an excellent porous superabrasive grindstone.

The method for producing a porous superabrasive grindstone of the present invention comprises:
Superabrasive grains made of diamond or cubic boron nitride having an average grain size in the range of 0.5 μm to 60 μm, a bulk density in the range of 0.5 to 2 times the superabrasive grains, and the superabrasive grains. And a coefficient of thermal expansion within the range of 0.3 to 3 times ,
A single element consisting of Zr, Cr, Mo, Ta and V,
Oxides of Ti, Si, and W, and nitrides of Si
The powder mixture obtained by mixing with one or more kinds of binder particles selected from the group consisting of 0.5 Tm (Tm is the melting point of the binder or the liquidus formation temperature expressed in absolute temperature K). )
The sintering is performed at the following temperature, and the sintering is performed at 5 MPa to 5 MPa.
Sintering temperature 600-15 under pressure within the range of 0 MPa
Since it is performed within the scope of 00 ° C., while maintaining a uniform high grinding efficiency, porous with high mechanical strength
A quality superabrasive grindstone is obtained.

[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 the relationship between the grinding pressure and the grinding amount of the object to be ground in the grindstone samples of Examples and Comparative Examples.

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

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

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

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

8A, 8B and 8C 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 ... Sintered surface 4 ... pores 5 ... 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) Reference JP-A-58-82677 (JP, A) JP-A-48-86190 (JP, A) JP-A 61-67740 (JP, A) JP-A-7-75972 (JP , A) JP-A-5-239585 (JP, A) JP-A-63-54488 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B24D 3/10 B24D 3/06

Claims (6)

(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, wherein the binder particles are It has a bulk density within the range of 0.5 times to 2 times that of the abrasive grains and a thermal expansion coefficient within the range of 0.3 times to 3 times that of the above-mentioned superabrasive grains , and contains W, Zr, Cr, Mo, From Ta and V
Elemental elements, oxides of Ti, Si, and W, and
And at least one selected from the group consisting of Si nitrides.
On the other hand, the porosity of the sintered body is 5% to
A porous superabrasive grindstone characterized by being set within a range of 60% . 2. The porosity is in the range of 28.3% to 50.8%.
A porous superabrasive grindstone characterized by being formed inside the enclosure . 3. Superabrasive grains composed of diamond or cubic boron nitride having an average grain size in the range of 0.5 μm to 60 μm, and a bulk density in the range of 0.5 to 2 times the superabrasive grains. And a coefficient of thermal expansion within the range of 0.3 to 3 times that of the superabrasive grains, and from W, Zr, Cr, Mo, Ta and V
Elemental elements, oxides of Ti, Si, and W, and
And one or more kinds of binder particles selected from the group consisting of Si nitride and Si, and the resulting powder mixture is mixed with 0.5 Tm.
(Tm is the absolute temperature ° is the melting point or liquidus generation temperature of the binder represented by K) with sintering at a temperature below the sintering
At a sintering temperature of 5 MPa to 50 MPa.
A method for producing a porous superabrasive grindstone, which is performed at a temperature of 600 to 1500 ° C. 4. The mixing of the superabrasive grains and binder particles,
The method for producing a porous 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 sintering of the porous superabrasive grinding wheel according to claim 3 or 4, characterized in that by using a discharge plasma sintering method or a hot isostatic press sintering method Manufacturing method. 6. The oxygen partial pressure in the atmosphere during sintering is set to 0.
The method for producing a porous superabrasive grain grindstone according to any one of claims 3 to 4, wherein the pressure is set to 01 MPa or less.