JP2003181765A - Porous supergrain grinding stone and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a porous supergrain grinding stone, which is able to efficiently grind a workpiece and has excellent strength, and to provide a method for manufacturing the same. <P>SOLUTION: The porous supergrain grinding stone is composed of supergrains 1, such as diamond or cubic boron nitride, having a mean grain size not more then 60 μm and bond 3 which is able to form a fused phase 7 by fusing with the supergrains under heated conditions. The bond 3 is a porous body having continuous pores 5. The thickness t of the fused phase 7 formed at the interface between the bond and the supergrain is not more than 1.5 μm. The fused phase is composed of the component of the supergrain and one or more kinds selected from the group composed of Ti, Ni, Fe, Si, Ta, W, Cr, and Co. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Abrasive grains of diamond or cubic boron nitride (hereinafter referred to as "cBN") have an extremely high hardness and are called "superabrasive grains". They are called steel, high hardness metal, glass, ceramics, It is often used for precision grinding of stone materials. A superabrasive grindstone using the superabrasive grains (hereinafter, simply referred to as "grindstone") is generally manufactured by bonding the superabrasive grains with a binder and molding the superabrasive grains. As the binder, a synthetic resin is called a resin bond grindstone, a vitreous bond is called a vitrified bond grindstone, and a metal is called a metal bond grindstone, each of which is properly used depending on the characteristics of the object to be ground.

In recent years, as represented by integrated circuits using a thin film process, the density of devices has been increased and the devices have become widely used.
For example, fine cutting with a thickness of 0.3 mm or less has been required, and a grinding blade with a thin blade that enables this cutting has been demanded.

Conventionally, most of the thin blade grindstones used for this type of fine grinding were metal bond grindstones from the viewpoint of strength. The metal bond grindstone is produced by an electroforming method or a sintering method using Ni or a bronze alloy as a binder, but since the structure of the binder phase is dense, dressing (including dressing) is difficult, It required complicated and expensive technology and equipment such as electrolysis.

That is, in order to activate the grindstone, it is necessary to project the cutting edge of the superabrasive grains from the surface of the binder phase. Generally, when the grindstone is molded, on the surface of the grindstone,
The superabrasive grains and the binder phase are at the same level. In order to project the cutting edge of the superabrasive grains from this state, the surface layer of the binder phase must be removed to a certain depth while leaving the superabrasive grains. This work is "sharpening", but if the surface layer of the binder phase is smooth, it is extremely difficult to remove only the surface layer of the binder phase while leaving the superabrasive grains, for example, by scraping. It is difficult and requires a complicated and expensive method such as eluting and removing the surface layer of the binder phase by an electrolytic method or the like.

On the other hand, a vitrified bond grindstone is generally produced by molding a mixture of ceramic particles and a superabrasive grain, which are binders, and sintering the mixture under pressure. The binder phase is porous. Since the texture is coarse, no special sharpening is required, and grinding debris generated during the grinding operation is captured and eliminated in the pockets formed by the pores, so clogging is less likely to occur and the cutting of abrasive grains is also avoided. Even if the blade wears, the binder phase is coarse and brittle, so it falls off moderately and a new cutting edge appears,
Blinding is also unlikely.

However, the vitrified bond grindstone is not only brittle in the binder phase, but also weak in the bond strength between the binder and the superabrasive grains, so that it can be made into a thin blade grindstone having a thickness of 0.3 mm or less, for example. In addition, since it easily causes eye spillage, it is not economical because wear is severe when grinding a highly hard-to-be-ground object to be ground with a strong pressing pressure.

[0008]

Therefore, in order to obtain a grindstone having high grinding efficiency, high strength, and strong bonding force between the bonding material and the superabrasive grains, pores are formed in the structure of the metal bond grindstone. It was considered to be porous. This porous metal bond grindstone mixes, for example, superabrasive grains and binder metal particles and is compression molded into the shape of the grindstone with or without the use of a thermally volatile binder to keep the binder metal granular. It can be produced by sintering the particles as they are, and by applying a temperature and a pressure at which bonding between the bonding material particles and the superabrasive particles occurs.

The porous metal-bonded grindstone manufactured in this manner has a strong binding force between the binder and the superabrasive grains, and has a rough binder phase, so that it has good sharpness and is produced during the grinding operation. Grinding debris is captured and removed by the pore pockets, so clogging is less likely to occur, and even if the cutting edge of the abrasive grains wears, the binder phase is coarse because it falls off moderately and a new cutting edge appears. , It was expected that blindness would not occur easily.

However, in the above-mentioned porous metal-bonded grindstone, although the bonding between the superabrasive grains and the bonding material is strong, the porosity is increased so that the cutting edge of the superabrasive grains is projected to make the grindstone sharp. If you try to improve it, the amount of eye bleeding increases and the wear becomes more severe.If you lower the porosity and lower the cutting edge height, the eye spillage will decrease, but since the worn superabrasive grains do not fall off, clogging and eyes There is a problem that crushing is likely to occur. In order to solve this problem, there has been a demand for a technique for imparting a bonding force between the superabrasive grains and the bonding material while maintaining an appropriate porosity and at which spillage is unlikely to occur.

The present invention has been made to solve the above problems. Therefore, the purpose thereof is to have a strong bonding force between superabrasive grains and a binder phase, and to improve sharpening property, spilling property, clogging property, It is an object of the present invention to provide a porous superabrasive grain grindstone having a well-balanced improvement in crushing property and the like and having a strength that can be used as a thin blade grindstone for microfabrication, and a method for producing the same.

[0012]

[Means for Solving the Problems] The above-mentioned problems are selected from the group consisting of diamond and cubic boron nitride, and the superabrasive grains having an average grain size of 60 μm or less are fused with the superabrasive grains under heating. And a binder that can form a fused phase by
This binder is a porous body having continuous pores, a fused phase thereof is formed at the interface between the binder and superabrasive grains, and the thickness of the fused phase is 1.5 μm or less, and the fused phase is ,
Superabrasive grain constituents and Ti, Ni, Fe, Si, Ta,
The problem can be solved by providing a porous superabrasive grindstone characterized by comprising at least one selected from the group consisting of W, Cr, and Co. The above-mentioned problems are superabrasive grains selected from the group consisting of diamond and cubic boron nitride and having an average grain size of 60 μm or less, and a binder capable of being fused with the superabrasive grains under heating to form a fused phase. Consists of
This binder is a porous body having continuous pores, a fused phase thereof is formed at the interface between the binder and superabrasive grains, and the thickness of the fused phase is 1.5 μm or less, and the fused phase is ,
The problem can be solved by providing a porous superabrasive grindstone characterized by containing Cu or Ag.

The term "fused phase" as used herein means a forming phase composed of a eutectic mixture, a solid solution or a compound formed by the superabrasive grains and the atoms of the bonding material intermingling at the contact interface by thermal diffusion. To do.

The above binders are Fe, Cu, Ni and C.
a single element consisting of o, Cr, Ta, W, Ti, Si, and Zr, and Co, Cr, Ta, V, Nb, W,
Ti, Si, and Zr carbides, Ti, Si, A
l, Ce, Mg, Fe and Zr oxides, Ta, T
It is preferably at least one selected from the group consisting of i and Si nitrides, and Ta, Ti, and Si borides.

The thickness of the above-mentioned fused phase is from 0.05 μm to 0.1 μm.
It is preferably within the range of 5 μm. Further, the porosity of this porous superabrasive grain grindstone is preferably in the range of 5% to 60%, and more preferably in the range of 5% to 45%.

The present invention is also selected from the group consisting of diamond and cubic boron nitride, having an average particle size of 60 μm.
Below, Ti, Ni, Fe, Si, Ta, W, C
a metal-coated superabrasive grain coated with a metal layer having a thickness of 1.5 μm or less, which is one or more selected from the group consisting of r and Co, and is fused with the metal-coated superabrasive grain under heating. The binder phase capable of forming a fusion phase is mixed, and in the state where this powder mixture is molded, the fusion phase is formed in the metal layer portion of the metal-coated superabrasive grains to a thickness of 1.5 μm or less, Moreover, the binder particles are sintered to each other and the porosity is 5% to 6
There is provided a method for producing a porous superabrasive grindstone, which comprises a step of sintering by applying a temperature and a pressure adjusted so as to be within a range of 0%. The present invention is a metal-coated superabrasive grain selected from the group consisting of diamond and cubic boron nitride, having an average particle size of 60 μm or less, and a coating layer of Cu or Ag having a thickness of 1.5 μm or less,
The binder particles capable of forming a fused phase by fusing with the metal-coated superabrasive grains under heating are mixed, and in a state where this powder mixture is molded, those particles are added to the metal layer portion of the metal-coated superabrasive grains. Sintering under controlled temperature and pressure so that the fusion phase is formed to a thickness of 1.5 μm or less, and the binder particles sinter and the porosity falls within the range of 5% to 60%. There is provided a method for producing a porous superabrasive grain grindstone, characterized by including the step of:

Examples of the binder particles include Fe, Cu,
Ni, Co, Cr, Ta, V, Nb, W, Ti, Si,
And a simple element consisting of Zr, Co, Cr, and T
a, W, Ti, Si, and Zr carbides, Ti, S
Oxides of i, Al, Ce, Mg, Fe and Zr, T
a, Ti, and Si nitrides, and Ta, Ti,
And one or more kinds of particles selected from the group consisting of Si boride and having an average particle diameter within the range of 5% to 50% of the average particle diameter of the superabrasive particles. Is preferred.

The temperature and pressure applied during the above sintering are
At the interface between the superabrasive grains and the binder particles, the fusion phase of them is 0.
It is preferable to adjust the thickness so that the thickness is in the range of 05 μm to 0.5 μm. In addition, the temperature and pressure applied during the above-mentioned sintering are preferably adjusted so that the porosity is in the range of 5% to 45%.

As the above-mentioned superabrasive grains, Ti, Ni,
At the time of sintering, using metal-coated super-abrasive grains coated with a metal layer of at least one selected from the group consisting of Fe, Si, Ta, W, Cr, and Co and having a thickness of 1.5 μm or less. It is preferable to adjust the temperature and pressure so that the metal layer serves as a fusion phase to bond the superabrasive grains and the binder particles. Alternatively, as the above-mentioned superabrasive grains, C
A material coated with a coating layer that is one of the above binders containing u or Ag is used, and during sintering, this coating layer serves as a fusion phase to bond the superabrasive grains and the binder particles. Moreover, it is preferable to adjust the temperature and the pressure.

It is preferable that the above-mentioned sintering is carried out by a discharge plasma sintering method, the temperature at the time of sintering is in the range of 600 ° C. to 2000 ° C., and the pressure is in the range of 5 MPa to 50 MPa. Alternatively, it is preferable that the sintering is performed by a hot press sintering method, the temperature at the time of sintering is in the range of 600 ° C. to 2000 ° C., and the pressure is in the range of 5 MPa to 50 MPa.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The basic mode of the present invention will be described below with reference to the accompanying drawings. (Basic Configuration Example 1) FIG. 1 schematically shows the configuration of one basic example of a porous superabrasive grain grinding stone (hereinafter referred to as "main grinding stone") of the present invention corresponding to claim 1. In FIG.
Reference numeral 10 indicates the configuration of the surface layer portion of the main grindstone. The present grindstone 10 has an average particle size of 20 μm to 30 μm in this embodiment.
(# 660) superabrasive grain 1 consisting of diamond single crystal,
, Are fixed as Ni as a binder 3 which is a simple element that can fuse with the superabrasive grains 1 under heating to form a fused phase. A large number of continuous pores 5 are formed in the phase of the binder 3 (binder phase), whereby the main grindstone 10 is a porous body having a porosity of 39%, that is, in the range of 5% to 60%. Has become.

In the main grindstone 10, the superabrasive grains 1 and the bonding material 3
At the contact interface with and, a fusion phase 7 is formed by atomic diffusion from either or both of them. The thickness t of the fused phase 7 is about 0.43 μm in this embodiment,
That is, it is 1.5 μm or less.

In this grindstone, since the superabrasive grains 1 and the bonding material 3 are firmly bonded by the fused phase 7 having the limited thickness as described above, the superabrasive grains 1 are wasted during the grinding operation. It will never fall out. It was found that when the thickness of the fused phase exceeds 1.5 μm, the fused phase 8 is separated from the superabrasive grains 1 and the binding force between the superabrasive grains 1 and the bonding material 3 is reduced as shown in FIG. .

In addition, since the phase of the binder 3 is porous and the surface of the present grindstone is rough, dressing is automatically performed during grinding work without using a complicated means such as electrolytic dressing. Be seen. Moreover, since the porosity is high, the cutting edge of the superabrasive grain 1 protrudes higher than the surface level of the bonding material 3, and a sharp whetstone can be obtained.

Further, in the present grindstone 10, since the phase of the binder 3 is porous with continuous pores, the cooling liquid can be circulated through the pores 5 to enhance the cooling effect of the grindstone.
The pocket 9 formed on the surface by the pores 5 is
Clogging is less likely to occur because it captures grinding debris generated during grinding work and removes it outside the system.

Furthermore, since the bonding material 3 becomes brittle to some extent due to the presence of the pores 5, when the grinding is performed to such an extent that the cutting edge of the superabrasive grain 1 is worn, the worn superabrasive grain 1 is removed.
And a part of the bonding material 3 which is bonded to the periphery of the bonding material 3 via the fusion phase 7 are peeled off together to prevent crushing of eyes, and
By removing the outermost layer of the grindstone, the superabrasive grains 1 in the inner layer newly appear on the surface and the grinding force of the main grindstone 10 is maintained.

The main grindstone 10 of the basic configuration example 1 was manufactured by the following method. Superabrasive grains 1 consisting of # 660 artificial diamond single crystal and Ni powder having a purity of 99.5% or more and an average grain size of 5 μm were mixed in a volume ratio of 3 (superabrasive grains): 4 (bonding material), The obtained powder mixture was filled in a doughnut-type die of a discharge plasma sintering apparatus, and the temperature was set to 800 ° C., 10 MPa, 5 MPa.
Example 1 as a donut disk-shaped sintered body having an outer diameter of 92 mm, an inner diameter of 40 mm, and a thickness of 0.3 mm was sintered under the condition of minutes.
The grindstone 10 was obtained. The porosity of this product was 39%. Further, the thickness of the fused phase 7 was measured by an electron microscope, and it was about 0.1 μm. No void was observed at the interface between superabrasive grain 1 and fused phase 7.

Using the grindstone of the basic structure example 1 as a sample, a cutting test was conducted by a constant pressure grinding method using a tool grinder. Dressing of the grindstone was performed using a GC # 240 stick.
AlTiC (Al ₂ O ₃ · TiC) as the object to be ground (bending strength 588 MPa, Vickers hardness 19.1 GPa)
A block having a cross section of 2 mm × 5 mm was used.

As a comparative sample, using the same superabrasive grains and binder as in Example 1, an outer diameter of 92 mm prepared by an electrodeposition method,
A donut disk-shaped metal bond grindstone having an inner diameter of 40 mm and a thickness of 0.3 mm was prepared by ELID, and the grinding speed of the grindstone sample of Example 1 was compared with that of the basic configuration example 1. It was possible to cut the object to be ground at a grinding speed 1.5 times higher than the above. This result shows that the grinding efficiency of the grindstone of the basic configuration example 1 is superior to that of the conventional metal bond grindstone.

As shown in the basic configuration example 1 and FIG. 1, the present grindstone basically comprises superabrasive grains 1 and a binder 3, and the phase of the binder 3 is formed into a porous structure having continuous pores. Is
At the interface between the bonding material 3 and the superabrasive grain 1, a fusion phase 7 of them is formed.

The super-abrasive grain 1 used here is either single crystal or polycrystal diamond, or single crystal or polycrystal cBN (cubic boron nitride), or a mixture of any two or more thereof. The average particle size is 60μ
m or less. If the average particle size exceeds 60 μm, the surface to be ground becomes rough and unsuitable for use in, for example, fine grinding such as cutting the substrate with a grinding allowance of 0.3 mm or less, or lapping.

As the super-abrasive grains, it is preferable to use diamond having the highest hardness when the object to be ground such as ceramics material is finely processed. The diamond may be a single crystal or a polycrystal, and may be a natural diamond or an artificial diamond. Further, since iron-based objects to be ground have a problem in using diamond, it is preferable to use cBN in this case. This cBN may be either single crystal or polycrystal.

The binder 3 used together with the above-mentioned superabrasive grains 1 may be any as long as a fused phase is formed at the interface with the selected superabrasive grains 1 during heating. However, particularly preferable as the binding material 3 of the main grindstone for precision grinding is
Fe, Cu, Ni, Co, Cr, Ta, V, Nb, W,
Elemental element consisting of Ti, Si, Zr; Co, Cr, T
Carbides of a, W, Ti, Si, Zr; Ti, Si, Z
Oxides of r, Al, Ce, Mg, Fe; Ta, Ti, S
i nitride; or Ta, Ti, Si boride, or a mixture of any two or more thereof.

When these bonding materials 3 are heated in the range of, for example, 600 ° C. to 2000 ° C. in contact with the above-mentioned superabrasive grains 1, atoms are diffused at the interface, and
As shown in Figure 1, a fused phase 7 consisting of a eutectic mixture, a solid solution or a compound is formed. The super abrasive grain 1 and the bonding material 3 are
The fusion phase 7 provides a strong bond. Therefore, even if the surface is deeply sharpened to improve sharpness and the contact area between the superabrasive grains 1 and the bonding material 3 becomes relatively small, it is unlikely that the superabrasive grains 1 will be unnecessarily removed during the grinding operation.

However, it has been found that when the thickness of this fused phase becomes excessively large, separation occurs between this fused phase 8 and the superabrasive grains 1 as shown in FIG. This is because diamond has a high mobility of C and cBN has a high mobility of N with respect to the contact interface due to the excessive generation of the fusion phase, a depletion layer is formed, and a displacement stress occurs in the horizontal direction. Since the thermal expansion coefficient of the main body is different from that of the fused phase 8, it is considered that wrinkles are generated in the fused phase 8 due to thermal change. From this viewpoint, the thickness of the fused phase 7 in the present grindstone is set to 1.5 μm or less. In particular, it is preferably 0.5 μm or less.

On the other hand, if the thickness of the fused phase 7 is made extremely small, the fused phase 7 is not formed as a uniform film on the surface of the superabrasive grains but is scattered like islands as shown in FIG. I found out. In this case, the bonding between the superabrasive grains 1 and the bonding material 3 becomes insufficient. The minimum thickness at which the fused phase 7 is uniformly formed on the surface of the superabrasive grain 1 is the superabrasive grain 1 and the binder 3
It is usually about 0.05 μm, though it varies depending on the type, average particle size, temperature, pressure and time applied during production. From this viewpoint, the thickness of the fused phase 7 is preferably 0.05 μm or more.

The thickness of the fused phase 7 can be controlled by adjusting the temperature and time applied when sintering the powder mixture of the superabrasive grains 1 and the binder 3. Since this temperature and time vary depending on the type and particle size of the selected superabrasive grains 1 and the bonding material 3, the sintering method and apparatus, the pressure during sintering, etc., the suitable temperature actually used is determined by experiments. Should be. A general selection temperature range is 600 ° C to 2
It is 000 ° C.

The present grindstone is made porous. The porosity is preferably in the range of 5% to 60%, particularly preferably in the range of 5% to 45%. If the porosity is less than 5%, the pocket volume due to the pores will be insufficient, and the circulation of the cooling liquid will be insufficient, so that clogging easily occurs.
%, Especially above 60%, the physical properties of the binder phase deteriorate,
Eye spilling and eye crushing are likely to occur, and when a thin blade grindstone is manufactured, it easily breaks.

In manufacturing the porous main grindstone, the binder 3 is mixed as a powder with the superabrasive grains 1, the powder mixture is filled in a mold, and the superabrasive grains 1 and the binder particles are pressurized. (3
It is preferable to sinter p) and the binder particles 3p. At this time, the porosity can be adjusted to a suitable range by adjusting the average particle size, mixing ratio, sintering pressure, sintering temperature, sintering time, etc. of each of the superabrasive grains 1 and the binder particles 3p. it can.

The average particle size of the binder particles 3p is preferably in the range of 5% to 50% of the average particle size of the superabrasive grains 1. When the particle size ratio of the binding material particles 3p to the superabrasive particles 1 approaches 1: 1, the superabrasive particles 1 and the binding material particles 3 are even in the close packing state, as schematically shown in FIG. 4 (a).
Since there are few contact points with p, the binding force at the time of sintering is insufficient, and it is easy to cause spillage.

If the particle size ratio of the binder particles 3p to the superabrasive grains 1 is in the range of 1: 0.05 to 0.5, as shown in FIG. Since the number of contact points with the binder particles 3p is sufficiently large, the fused phase 7 is formed in a thin film shape on almost the entire surface of the superabrasive grains 1 during sintering, and the binding force between the superabrasive grains 1 and the binder 3 is large. And the appropriate porosity is maintained.

When the particle size ratio of the binder particles 3p to the superabrasive grains 1 is smaller than 1: 0.05, the number of contacts 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 large. As it becomes smaller, the sintered product does not differ much from a non-porous metal bond grindstone.

When the mold is filled with the superabrasive grains 1 and the binder particles 3p, and the pressure and temperature are applied to sinter the binder particles 3p.
Part of which melts and which is in contact with the superabrasive grain 1 wets and spreads on the surface thereof to form a fused phase 7. When the binder particles 3p are in contact with each other, fusion occurs on the contact surface, and as shown in FIG. 5, the binder particles 3p are connected to each other by the neck 3n, and the non-contact portion forms the continuous pores 5. Form.

During sintering, the mixing ratio of the superabrasive grains 1 and the binder particles 3p is 1: 3 by volume ratio of superabrasive grains to binder particles.
It is preferably 2: 1. When the ratio of super abrasive grains 1 is less than 1: 3, the grinding ability becomes insufficient,
When the ratio of the superabrasive grains 1 is more than 2: 1, the density of the superabrasive grains 1 is too high, the strength of the sintered body is lowered, and spills and the like are likely to occur.

Various conventionally known methods can be adopted for the sintering. Of these, the spark plasma sintering method is a particularly preferable method. The spark plasma sintering method can be performed using, for example, a spark plasma sintering device shown in FIG. In FIG. 6, the spark plasma sintering apparatus is
A die 24, an upper punch 22 and a lower punch 23 which are inserted into the die 21, and a base 24 which supports the lower punch 23 and also serves as one electrode when a pulse current described later is passed.
And a base 25, which is the other electrode for pressing the upper punch 22 downwards and sends a pulse current, and a thermocouple 27 for measuring the temperature of the powder raw material 26 sandwiched between the upper and lower punches 22 and 23. is doing.

A separate energizing device is connected to the bases 24 and 25, and a pulse current for plasma discharge is supplied from the energizing device to the upper and lower punches 22, 23.
Is applied to. In this spark plasma sintering apparatus, at least a portion sandwiched between the base 24 and the base 25 is housed in a chamber (not shown), and the inside of the chamber is evacuated to a vacuum and atmospheric gas is introduced. It has become.

The powder mixture 26 of superabrasive grains and a binder is filled in a die 21 formed into a predetermined grindstone shape, and the inside of the chamber is evacuated or replaced with an inert gas atmosphere. The punches 22 and 23 apply pressure compression from above and below, and then a pulse current is applied. According to this discharge plasma sintering method, the raw material powder can be uniformly and quickly heated to the sintering temperature by adjusting the applied current, and the temperature can be strictly controlled.

Examples of the discharge plasma sintering apparatus that can be used in the above-mentioned discharge plasma sintering method include a model SPS-2050 type discharge plasma sintering apparatus manufactured by Sumitomo Coal Mining Co., Ltd. In addition to the spark plasma sintering method, for example, HIP (Hot Isostatic Press) often used for hot press sintering method and sintering of ceramic powder.
The method can be advantageously adopted.

Next, an example of the basic structure of the present grindstone using the HIP method will be described. (Basic configuration example 2) 1 (superabrasive grain): 1.28 (bonded) superabrasive grains made of # 1000 artificial diamond single crystal and cast iron powder containing 3.11% by weight of carbon and having an average grain size of 5 μm 2% by weight of wax as a molding aid, and the pressure is 10MP using a uniaxial press.
The powder was pressed for 1 minute with a to obtain a powder compression molded product. This powder compression-molded product was treated in vacuum at 800 ° C. for 1 hour to remove wax and pre-fire.

Next, after shape shaping, 1000
Firing was performed by the HIP method under the conditions of holding at 200 ° C. and 200 MPa for 1 hour to obtain a fired body. The porosity of this product is 53
%Met. The thickness of the fused phase was measured by an electron microscope and found to be about 1.5 μm. Then, as a result of observation, voids began to be formed at the interface between the superabrasive grains and the fused phase. From this, the allowable upper limit of the thickness of the fusion phase is 1.5
It was determined to be μm. Finish this fired body into a cup grindstone,
The grindstone of Example 2 was used.

Using this grindstone as a sample, a cutting test was conducted by a constant pressure grinding method using a tool grinder. Dressing is G
This was performed using a simple brake truer of C # 240, and the object to be ground was a cross section of AlTiC (Al ₂ O ₃ .TiC) 2.
A block of mm × 5 mm was used.

As a comparative sample, a vitrified grindstone containing superabrasive grains in the same ratio as in the basic constitution example 2 was prepared, and the grinding speed of the grindstone sample of the example 2 was compared with that of the basic constitution example 2. The grinding speed was about 3 times that of the above. This result shows that the grindstone of Example 2 is superior in grinding efficiency to the vitrified grindstone.

Table 1 below shows the discharge plasma method (hereinafter abbreviated as "SPS method") when various binders are used.
And the optimum sintering temperature range in the hot pressing method and the optimum sintering pressure range common to both sintering methods are shown. Table 1 shows the case where artificial diamond having an average particle size of 15 μm is used as the superabrasive particles.

[0054]

[Table 1]

The pores, which are one of the three elements of the grindstone, are used for discharging grinding dust, supplying cooling liquid, and making the cutting edge protrude from the binder phase to improve sharpness and dressing (dressing) property. is important. From this viewpoint, an example in which an example of the present grindstone is compared with a commercially available non-porous cast iron bond grindstone will be shown below.

(Basic Structure Example 3) Diamond abrasive grain # 10
0 / # 110 (average particle size 180 μm) and carbon amount 3.5
A cast iron powder having a weight percentage of 20 μm or less and manufactured by an atomizing method is mixed in a volume ratio of 30 (superabrasive grains): 40 (bonding material), and 2 wt% of wax is added, followed by powder molding and vacuum forming. The wax was removed under the conditions of medium temperature of 1000 ° C. for 1 hour and sintered by HIP method under the condition of nitrogen atmosphere of 1120 ° C., 200 MPa for 1 hour to obtain a grindstone with a porosity of 26% (basic constitution example 3). .

The grinding amount and the grinding energy of the grindstone of the basic configuration example 3 and the commercially available non-porous cast iron bond grindstone (# 100 / # 120) were measured by the constant pressure method.
Grinding object of constant pressure grinding is alumina (bending strength 588MP
a, Vickers hardness 19 GPa) cross section 3 mm x 4 mm
Is a block.

The above-mentioned objects to be ground were pressed against the surface of each grindstone formed into a cup shape at 0.4 MPa, and the peripheral speed was 1100.
Grinding was performed at m / min, the grinding resistance and the removal amount at that time were measured, and the grinding amount (grinding volume per second) and the grinding energy (grinding resistance × peripheral speed / removal amount) were calculated. The results are shown in Table 2.
Shown in.

[0059]

[Table 2]

From the above results, the porosity is almost 0% (5%
Example 3 compared to the commercially available non-porous cast iron bond grindstone
In the whetstone of No. 3, the grinding amount per hour is 6 times or more, and the grinding energy is about 1 / 2.5, and it is clear that the pores bring about a great improvement effect on the grinding efficiency.

(Basic Structure Example 4) Superabrasive grains 1 and binder particles 3
Even if the type and particle size of p are fixed, the porosity of the obtained grindstone changes depending on the sintering conditions. As an example, # 10
The artificial diamond of 00 (average particle size 10 μm to 20 μm) was used as the superabrasive grain 1, and the cast iron powder having an average particle size of 5 μm was used as the binder particles 3p.
A disc-shaped grindstone having a thickness of 0.5 mm and a thickness of 0.5 mm was manufactured, and the temperature and pressure during molding and the porosity of the obtained grindstone were measured. The results are shown in Table 3.

[0062]

[Table 3]

From the results shown in Table 3, it is generally recognized that the lower the sintering temperature and the lower the sintering pressure, the higher the porosity.

If the porosity is too large, the physical properties of the grindstone deteriorate, and the grindstone also wears out significantly. This porosity also changes depending on the manufacturing method. Below, spark plasma sintering method (SPS
Method) and the HIP method, and the comparison between the physical properties and the grinding efficiency caused by the difference are shown in the following examples.

(Basic configuration example 5) Average particle diameter 10 μm to 20
A volume ratio of artificial diamond of μm and atomized cast iron powder with a carbon content of 3.11% by weight and an average particle size of 5 μm is 25
(Super abrasive grain): 32 (bonding material) mixed, HIP method and SP
A cup-shaped grindstone was produced using the S method.

As shown in Table 4, the grindstone produced by the HIP method has a porosity of 53%, and when superabrasive grains of about # 1000 are used, the porosity increases. Further, in the SPS method, the same material was used at 780 ° C. and 720 ° C. and 10 MPa.
Sintering was performed under the conditions described above to obtain grindstones having porosities of 27% and 36%, respectively. Since the SPS method is a pressure sintering method, the porosity can be controlled by selecting the pressure in addition to the temperature, and it can be said that the controllability of the porosity is excellent. The hot pressing method, which is also a pressure sintering method, can provide the same results as the SPS method.

Each of the above-mentioned grindstone samples was compared with a commercially available vitrified grindstone and a grinding performance test was conducted by a constant pressure method. The object to be ground is a block of AlTiC (Al ₂ O ₃ .TiC) having a cross section of 2 mm × 5 mm.

The object to be ground was pressed at a pressure of 0.3 MPa against the surface of each grindstone formed into a cup shape, and the peripheral speed was 1100.
Grinding was performed at m / min, the grinding resistance and the removal amount at that time were measured, and the grinding speed (grinding length per second) and the grinding energy (grinding resistance × peripheral speed / removal amount) were calculated. The results are shown in Table 4 together with the test results of the commercially available vitrified grindstone used as a comparative example.

[0069]

[Table 4]

From the above results, the porosity is 27% to 36%.
It can be seen that the SPS method grindstone has sufficiently good grinding performance as compared with the commercially available vitrified grindstone which is often used under these grinding conditions and is often used.
The grindstone with a porosity of 53% produced by the HIP method has a low Young's modulus, and when the grinding pressure is 1 MPa, the grinding duration time is 360
Abrupt wear occurred on the grindstone in seconds. From this viewpoint, a grindstone having a high porosity can be effectively used in applications where the grinding pressure is low, but it is preferable that the porosity is 45% or less in applications where the grinding pressure exceeds 1 MPa. .

Next, the grindstone of the present invention according to the present invention will be described. In the grindstone according to the present invention, the fused phase 7 is the superabrasive grain 1
And a porous superabrasive grindstone composed of at least one selected from the group consisting of Ti, Ni, Fe, Si, Ta, W, Cr, and Co.

As described above, in the case of the porous grindstone, it is generally important to maintain the bonding strength between the superabrasive grains and the binder, and in the main grindstone 10 described above, it is formed at the interface. By adjusting the thickness of the fused phase 7 to be formed, the formation of voids between the superabrasive grains 1 and the fused phase 7 is prevented, and good bond strength is obtained. At this time, if, for example, a certain elemental element, oxide, nitride, boride, or the like is used as the binder 3, a void is generated between the superabrasive grain 1 and the fused phase 7 depending on the case, and the bonding force is increased. May decrease.

One of the reasons for this is that the wettability of the above-mentioned binding material 3 with respect to the superabrasive grains 1 is insufficient under the sintering conditions.
As shown in FIG. 3, since the fused phase 7 is formed only in an island shape, the bonding force becomes insufficient. Further, the bonding material 3 and the superabrasive grains 1 generally form the fused phase 7 having high hardness. It is considered that the fused phase 7 formed and the thermal expansion coefficient of the superabrasive grain 1 are different from each other, so that cracks easily occur at the interface due to thermal change.

Ti, Ni, Fe, Si, Ta, W, C
r and Co have good wettability with the superabrasive grain 1, and Ni, Fe, Cr, and Co are materials that form the fused phase 7 that is relatively soft with the superabrasive grain 1. Since the fused phase 7 itself has a high affinity with the above-mentioned binder 3, the superabrasive grains 1 can be formed by interposing the fused phase 7.
The bonding material 3 and the bonding material 3 are firmly bonded to each other over a wide area, and peeling does not occur even when subjected to heat change. Also in this case, the thickness of the fusion phase 7 is adjusted to be 1.5 μm or less.

As shown in FIG. 7, the present grindstone according to the present invention has a metal layer 6 made of Ti, Ni, Fe, Si, Ta, W, Cr, or Co on the surface of the superabrasive grains 1 in advance. 1 m of metal-coated superabrasive grains coated with these metals and coated to 1.5 μm or less are mixed with binder particles 3p, and the mixture is molded and sintered at a suitable temperature and pressure. It can be manufactured by As a method of coating the surface of the superabrasive grain 1 with the metal layer 6, any of conventionally known plating techniques, vacuum deposition, sputtering, and the like may be used.

(Example) 1 m of metal-coated superabrasive grains in which Ni was coated on the surface of diamond abrasive grains as the metal layer 6, and Ni
The main grindstone of Example 6 was manufactured using powder binder particles 3p. Superabrasive grain 1 consisting of # 1000 artificial diamond single crystal was coated with 1 m of metal-coated superabrasive grain coated with 43% by weight of Ni, and Ni powder having an average grain size of 5 μm, 25 (superabrasive grain): 32 (bonding material ), And the obtained powder mixture was filled in a doughnut-type die of a discharge plasma sintering apparatus, compressed to 10 MPa to 20 MPa, applied with a pulse current, and sintered at 680 ° C to 780 ° C. .

The main grindstone obtained by the above method was a donut-shaped disc having an outer diameter of 92 mm, an inner diameter of 40 mm and a thickness of 0.45 mm, and the porosity was 27%. Approximately 10 mm of the tip of this grindstone was dressed to a thickness of 0.25 mm using a GC # 240 stick, and the AlTiC (Al ₂ O
_A grinding test was performed by a constant pressure grinding method using a test piece of ₃ / TiC) having a cross section of 5 mm × 2 mm as an object to be ground.

As a result of the test, this grindstone was used to grind the above-mentioned object to be ground at a grinding pressure of 0.5 MPa and a grinding speed of 0.2 mm ^3.
It was possible to grind in 1 / second. This means that the grindstone of Example 6 has a sufficiently practical strength even at a thickness of 0.25 mm, and a high-hardness workpiece having a thickness of 2 mm or more can be cut at high speed with a grinding allowance of 0.3 mm or less in width. It is shown that.

Next, a # 1000 artificial diamond single crystal coated with Ni was used as the superabrasive grain 1 m, and Ni particles with a particle size of 5 μm were used as the binder 3, and the sintering temperature and pressure in the SPS method were obtained. Table 5 shows the relationship of porosity of the grindstones
In addition, the Ni-coated # 1000 artificial diamond single crystal was used as the superabrasive grain 1 m, and the grain size was 5 μm as the binder 3.
Sintering temperature in the SPS method when using the cast iron particles of
Table 6 shows the relationship between the sintering pressure and the porosity of the obtained grindstone.

[0080]

[Table 5]

[0081]

[Table 6]

Next, the main grindstone according to the present invention will be described. In the present invention, fused phase 7 provides a porous superabrasive grindstone comprising Cu or Ag. Super abrasive grain 1
The thickness of the fused phase 7 at the interface between the binder 3 and the binder 3 changes depending on the sintering temperature, the pressure, and the sintering time. As described above, the thickness of the main grindstone must be controlled to be 1.5 μm or less. However, on the other hand, the sintering temperature, the pressure, and the sintering time also affect the binding force between the binder particles 3p. That is, in order to strengthen the physical strength of the present grindstone to the extent that it can be used as, for example, a thin blade grindstone, from the viewpoint of strengthening the bonding between the binder particles 3p, the conditions of sintering temperature, pressure, and sintering time are used. It will also be necessary to select

Under the conditions, the thickness of the fusion phase 7 is 1.
If it exceeds 5 μm, a means for suppressing the formation of the fused phase 7 is required. Cu and Ag have an effect of suppressing the growth of the fusion phase 7, and the thickness of the fusion phase can be controlled by adding them appropriately. Therefore, when these metals are present between the superabrasive grains 1 and the binder 3, the binder particles 3
The fused phase 7 does not grow excessively even under sintering conditions in which the p's are firmly bonded.

Since Cu and Ag are both soft metals, if the thickness of this layer is large, the hardness required as a grindstone may not be maintained in some cases. Therefore, Cu or A
The thickness of the fused phase 7 containing g is preferably 20% or less of the particle diameter of the superabrasive grain 1. Further, for example, the fusion phase 7 is Cu
When Fe and Fe are included, it is possible to form a hard coating film, but also in this case, peeling due to thermal change is likely to occur. Therefore, the thickness of the fused phase 7 is also equal to the grain size of the superabrasive grain 1. It is preferably 20% or less.

The present whetstone in which the fused phase 7 contains Cu or Ag is coated, for example, by coating the surface of the superabrasive grain 1 with a binder component containing Cu or Ag in advance to a thickness of 1.5 μm or less. It can be produced by mixing superabrasive grains with binder particles, shaping the mixture and sintering at a suitable temperature and pressure. As a method for coating the surface of the superabrasive grain 1 with the binder component containing Cu or Ag, any of conventionally known plating techniques, vacuum deposition, sputtering, and the like may be used.

[0086]

The porous superabrasive grindstone of the present invention is selected from the group consisting of diamond and cubic boron nitride and has an average particle size of 60 μm or less. And a binder capable of fusing to form a fused phase,
This binder is a porous body having continuous pores, a fused phase thereof is formed at the interface between the binder and superabrasive grains, and the thickness of the fused phase is 1.5 μm or less, and the fused phase is ,
Superabrasive grain constituents and Ti, Ni, Fe, Si, Ta,
Since it is made of one or more selected from the group consisting of W, Cr, and Co, it is a porous body, but the binding force between the superabrasive grains and the bonding material is strong, and it has excellent sharpness, and spills and clogging. Further, it is possible to obtain a physical strength that is less likely to cause crushing, has high grinding efficiency, and can be used as a thin blade grindstone having a thickness of 0.3 mm or less.

The fused phase is composed of the constituents of the superabrasive grains and Ni and F.
If it is formed of e, Cr, or Co, the fusion phase is relatively soft, and therefore the superabrasive grains are bonded to the bonding material without causing cracks between them. Can be further strengthened.

If the fused phase contains Cu or Ag, since Cu or Ag has a low affinity for the superabrasive grains, the thickness of the fused phase becomes excessive depending on the sintering conditions and causes the crack. To prevent

According to the manufacturing method of the present invention, although it is a porous body, the binding force between the superabrasive grains and the bonding material is strong, the sharpening property is excellent, and spilling, clogging, and crushing hardly occur, and grinding is performed. A superabrasive grindstone having high efficiency and physical strength that can be used as a thin blade grind having a thickness of 0.3 mm or less can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a surface layer portion in a basic configuration example of a porous superabrasive grain grindstone of the present invention.

FIG. 2 is a schematic cross-sectional view showing an example of a grindstone in which a fused phase has an excessively large thickness.

FIG. 3 is a schematic sectional view showing an example of a grindstone in which formation of a fused phase is insufficient.

4A and 4B are schematic cross-sectional views showing the mutual relationship of the particle diameters of superabrasive particles and binder particles, respectively.

FIG. 5 is a schematic cross-sectional view showing a sintered state of binder particles.

FIG. 6 is a sectional view showing an example of a discharge plasma sintering apparatus.

FIG. 7 is a schematic cross-sectional view showing a part of a method for manufacturing a porous superabrasive grain grindstone using metal-coated superabrasive grains.

[Explanation of symbols]

1 ... Super abrasive grain 3 ... Binder 5 ... Continuous pores 7: Fusion phase 9 ... Pocket 10 ... Surface layer of porous superabrasive grindstone t: thickness of fusion phase

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kozo Ishizaki             193, Nagaminecho, Nagaoka 193, Niigata Prefecture F term (reference) 3C063 AA02 AB05 BB02 BB07 BC02                       BC09 BG10 CC02 CC19

Claims (15)

[Claims] 1. Superabrasive grains selected from the group consisting of diamond and cubic boron nitride and having an average grain size of 60 μm or less, and a binder capable of fusing with the superabrasive grains under heating to form a fused phase. The binder is a porous body having continuous pores, a fused phase thereof is formed at the interface between the binder and superabrasive grains, and the thickness of the fused phase is 1.5 μm or less, The fused phase is composed of superabrasive grain constituents, Ti, and N.
A porous superabrasive grindstone, which comprises at least one selected from the group consisting of i, Fe, Si, Ta, W, Cr, and Co. 2. Superabrasive grains selected from the group consisting of diamond and cubic boron nitride and having an average grain size of 60 μm or less, and a binder capable of fusing with the superabrasive grains under heating to form a fused phase. The binder is a porous body having continuous pores, a fused phase thereof is formed at the interface between the binder and superabrasive grains, and the thickness of the fused phase is 1.5 μm or less, A porous superabrasive grindstone in which the fused phase contains Cu or Ag. 3. The fusion phase comprises a eutectic mixture, a solid solution, and a compound formed by the superabrasive grains and the atoms of the bonding material intermingling at the contact interface by thermal diffusion. Item 3. A porous superabrasive grindstone according to Item 1 or 2. 4. The binder is Fe, Cu, Ni, C.
a single element consisting of o, Cr, Ta, V, Nb, W, Ti, Si, and Zr, and Co, Cr, Ta, W,
Ti, Si, and Zr carbides, Ti, Si, A
l, Ce, Mg, Fe and Zr oxides, Ta, T
i, and Si nitride, and at least one selected from the group consisting of Ta, Ti, and Si boride. Grain whetstone. 5. The thickness of the fused phase is from 0.05 μm to 0.1 μm.
It is in the range of 5 μm, The porous superabrasive grindstone according to any one of claims 1 to 4, wherein 6. The porous superabrasive grindstone according to claim 1, wherein the porosity is in the range of 5% to 60%. 7. The porous superabrasive grindstone according to claim 1, wherein the porosity is in the range of 5% to 45%. 8. The porosity according to claim 1, wherein the particle size ratio of the binder particles to the superabrasive particles is in the range of 1: 0.05 to 1: 0.5. Quality superabrasive whetstone. 9. An average particle size of 60 μm or less selected from the group consisting of diamond and cubic boron nitride.
Ti, Ni, Fe, Si, Ta, W, Cr, and C
a metal-coated superabrasive grain coated with a metal layer having a thickness of 1.5 μm or less, which is one or more selected from the group consisting of
The binder particles capable of forming a fused phase by fusing with the metal-coated superabrasive grains under heating are mixed, and in a state where this powder mixture is molded, those particles are added to the metal layer portion of the metal-coated superabrasive grains. Sintering is performed by adjusting temperature and pressure so that the fusion phase is formed to a thickness of 1.5 μm or less, and the binder particles sinter and the porosity falls within the range of 5% to 60%. A method of manufacturing a porous superabrasive grain grindstone, which comprises the step of: 10. Metal-coated superabrasive grains selected from the group consisting of diamond and cubic boron nitride, having an average particle size of 60 μm or less and being coated with a coating layer of Cu or Ag having a thickness of 1.5 μm or less. , Mixing binder particles capable of forming a fused phase by fusing with the metal-coated superabrasive grains under heating, and forming a powder mixture of them in the metal layer portion of the metal-coated superabrasive grains. The fused phase of is formed to a thickness of 1.5 μm or less, and the binder particles are sintered so that the porosity is within the range of 5% to 60%. A method for manufacturing a porous superabrasive grain grindstone including a step of binding. 11. The binder particles include Fe, Cu,
Ni, Co, Cr, Ta, V, Nb, W, Ti, Si,
And a simple element consisting of Zr, Co, Cr, and T
a, W, Ti, Si, and Zr carbides, Ti, S
Oxides of i, Al, Ce, Mg, Fe and Zr, T
a, Ti, and Si nitrides, and Ta, Ti,
And one or more kinds of particles selected from the group consisting of Si boride and having an average particle diameter within the range of 5% to 50% of the average particle diameter of the superabrasive particles. The method for manufacturing a porous superabrasive grindstone according to claim 9 or 10. 12. The interface between the superabrasive grains and the binder particles,
12. The method according to claim 9, further comprising the step of sintering at a controlled temperature and pressure so that the fused phase is formed to a thickness in the range of 0.05 μm to 0.5 μm. A method for producing a porous superabrasive grindstone according to any one of claims. 13. The method according to claim 9, further comprising the step of sintering by applying a temperature and a pressure adjusted so that the porosity is in the range of 5% to 45%. A method for producing the porous superabrasive grindstone described. 14. The sintering is performed by a discharge plasma sintering method, and the temperature at the time of sintering is in the range of 600 ° C. to 2000 ° C. and the pressure is in the range of 5 MPa to 50 MPa. A method for manufacturing a porous superabrasive grindstone according to any one of claims 9 to 13. 15. The sintering is performed by a hot press sintering method, and the temperature at the time of sintering is in the range of 600 ° C. to 2000 ° C. and the pressure is in the range of 5 MPa to 50 MPa. A method for manufacturing a porous superabrasive grindstone according to any one of claims 9 to 13.