JPH1148150A - Vitrified bond diamond wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vitrified bond diamond wheel favourable in sharpness and favourable in surface roughness in grinding work of a polycrystal diamond sintered body(PCD). SOLUTION: The number of diamond chips containing rough diamond abrasive grains of more than 100 μm and less than 1500 μm in average grain diameter is specified as more than 40% and less than 80% against the total number of the chips by mixing and fastening the diamond chips containing rough diamond abrasive grains of more than 100 μm and less than 1500 μm in average grain diameter and fine diamond abrasive grains of more than 30% and less than 70% in average grain diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vitrified bonded diamond wheel for grinding a super hard material such as a polycrystalline diamond sintered compact (PCD), and more particularly to a polycrystalline cubic boron nitride sintered compact. (PCB
It is also applicable to the grinding process of N).

[0002]

2. Description of the Related Art PCD plays an important role in all fields where natural diamond has been used. PCD is a polycrystalline body obtained by placing fine and uniform diamond powder on a cemented carbide base and sintering it under ultra-high temperature and pressure. It is a very tough polycrystalline material that has no brittle defect and has a uniform structure.

[0003] Further, PCBN was invented to solve the weak point that diamond easily reacts with iron group metals, and is obtained by sintering cubic boron nitride (CBN) powder in the same manner as PCD. However, it is not as difficult as PCD.

[0004] PCD has been used as a cutting tool material and abrasion-resistant tool material because it has excellent physical properties such as high wear resistance, high fracture toughness and high Young's modulus as compared with cemented carbide, cermet and ceramics. ing. According to the usage form, it is cut into an appropriate size according to the purpose of use, and is fixed to a steel or cemented carbide shank and a cutter body to be used as a cutting tool or the like. At this time, in most cases, the shape of the cutting edge is finished by grinding together with the cemented carbide of the base in accordance with the machine to be used, the material to be processed, and the processing conditions.

Since the PCD cutting tool has excellent wear resistance, its life is several tens of times longer than that of a cemented carbide cutting tool.
Again, the cutting edge wears out as it is used. When the cutting edge is worn, the machined surface becomes rough or the cutting efficiency is reduced. Therefore, after a certain period of use, re-polishing is required. However, this re-polishing requires a long time for grinding because the hardness of PCD or the like is extremely high. This processing is performed using a specially designed high-precision, high-rigidity grinding machine.

For this grinding, a special metal bond diamond wheel or a resin bond diamond wheel to which metal powder is added as a filler is generally used. However, the main component of PCD is diamond, and the hardness of the diamond wheel and the workpiece is almost the same. Therefore, the diamond wheel is severely clogged, and the grinding process is frequently performed while dressing.

[0007]

One of the biggest problems in the re-polishing of PCD cutting tools and the like is that there is a large margin for rough machining. In many cases where re-grinding was determined to be necessary, not only the cutting edge was worn but also large chippings were generated.To completely remove these and return to the new cutting edge shape, considerable There is an allowance,
Efficient rough processing is a major factor in shortening the processing time. In order to improve the processing efficiency, a diamond wheel having a coarse diamond particle size may be used, but there is a certain limit to the roughening due to the reason that the surface roughness is too coarse or the chipping is large. On the other hand, if the diamond particle size is too fine, the efficiency of rough working is remarkably reduced, which is not preferable.

In addition to the PCD cutting tool, there are cases where it is necessary to ground the diamond layer of the PCD chip or to make the diamond layer thinner by grinding, and in these cases, there is a large margin for rough processing. Therefore, processing efficiency often becomes a problem.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems. That is, PC
It is an object of the present invention to provide a vitrified bond diamond wheel which can obtain a good surface roughness efficiently and in a short time in rough processing of re-polishing such as a D cutting tool and can shorten a finishing step. The feature thereof is a vitrified bond diamond wheel in which a diamond chip bonded by a vitreous or ceramic bond material is fixed to a base metal, and includes a coarse diamond abrasive having an average particle diameter of 100 μm or more and 1500 μm or less. Diamond chips and diamond chips containing fine diamond abrasive grains of 30% or more and 70% or less of the average particle diameter are fixedly mixed together and have an average particle diameter of 100 μm or more and 1500 or less.
The number of diamond chips containing coarse diamond abrasive grains of μm or less is 40% or more and 80% or less of the total number of chips.

[0010] The method of fixing the coarse-grained diamond chips and the fine-grained diamond chips may be alternate or two by two. However, care must be taken not to cause wheel imbalance. The proportion of the coarse-grained chips to be fixed must be at least 40% or more of the total number of chips.

The higher the degree of concentration of diamond in the diamond chip, the better the result is obtained, and the degree of concentration must be at least 100 or more. The concentration is preferably in the range of 100 to 150.

In use, the vitrified bonded diamond wheel must be particularly accurately trued and dressed by a brake-type dressing device or a drive-type dressing device using a conventional grindstone as a dresser. The dressing whetstone used for truing and dressing is the same or slightly finer than the diamond grain size of the vitrified bond diamond wheel, and good results are obtained when the bonding degree is G or H. If the dressing device generates vibration during truing and dressing, a dresser having a finer grain size and a softer coupling degree may be used. After the truing and dressing, the accuracy of the diamond layer surface is as follows: cylindricity or flatness is 5 μm or less, and runout accuracy is 5 μm or less, preferably cylindricity or flatness is 3
It is important that the deviation is within μm and the deflection accuracy is within 3 μm.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described in the section of Examples.

[0013]

【Example】

(Example 1) The outer diameter of the present invention is 300 mm, the width is 10 mm,
A 1A1-type vitrified bond diamond wheel was manufactured, and the effect of the invention was confirmed by a grinding test. The grinding test was performed by grinding the PCD with a horizontal axis surface grinder. The dimensions of the chip of the vitrified bond diamond wheel of Example 1 are outer R150, inner R
145, diamond layer thickness 3 mm, base layer thickness 2 m
m, the size of the tip was determined so that the outer arc length was about 31 mm and the outer periphery of the vitrified bond diamond wheel was divided into 30 equal parts. And diamond average particle size 3
Fifteen chips of 00 μm and 15 chips of diamond average particle diameter of 100 μm were alternately fixed to the base metal. As Comparative Example 1, 30 chips having an average diamond particle diameter of 300 μm were used.
Vitrified bonded diamond wheels were manufactured individually. Further, as Comparative Example 2, a vitrified bonded diamond wheel having 30 chips fixed with an average diamond particle diameter of 100 μm was manufactured. Then, the upper surface of the PCD chip was surface ground by mounting on a horizontal axis surface grinder manufactured by Okamotoko. Almost the same results were obtained.

(Embodiment 2) The outer diameter of the present invention is Φ300 mm,
A 10 mm wide, 1A1-type vitrified bond diamond wheel was manufactured, and the effects of the invention were confirmed by a grinding test. The grinding test was performed by grinding the PCD with a horizontal axis surface grinder. The dimensions of the chip of the vitrified bond diamond wheel of Example 2 are the outer R1
The size of the chip was determined so that 50, the inner radius R145, the thickness of the diamond layer was 3 mm, the thickness of the base layer was 2 mm, the outer arc length was about 31 mm, and the outer circumference of the vitrified bond diamond wheel was equally divided into 30 parts. Then, 22 chips having an average diamond particle diameter of 300 μm and 8 chips having an average diamond particle diameter of 100 μm were mixed and fixed to a base metal. Then, the upper surface of the PCD chip was subjected to surface grinding by attaching to a horizontal axis surface grinding machine manufactured by Okamotoko. In Example 2, sharpness and abrasion were the same as Comparative Example 1, and
The same results as in Comparative Example 2 were obtained for the surface roughness.

(Example 3) Outer diameter Φ150 mm, width 15 m
m, 6A2 type vitrified bond diamond wheel was manufactured, and a PCD chip was ground with a Sumitomo Hammond grinder to confirm the effect of the present invention. The outer dimensions of the chip are R
75, of which R is R60 and the thickness of the diamond layer is 3
mm, and the thickness of the bonding layer is 2 mm. Diamond particles are # 80 for coarse chips, # 120 for fine chips, and 100 for both. These were alternately fixed to complete the wheel. The grinding conditions of the PCD were as follows: the machine was a CPG grinding machine, the wheel peripheral speed was 850 m / min, the wheel pressing pressure was 20 kgf, and the truing and dressing was performed by attaching a WA grindstone to a drive type dressing device. As Comparative Example 3, a vitrified bonded diamond wheel with all chips having a particle size of # 80 and a Vitrified Bond diamond wheel with all chips having a particle size of # 120 as Comparative Example 4 were subjected to the same grinding test, and the vitrified bonded diamond wheel of the present invention was manufactured. As a result, the wheel of the present invention exhibited both the sharpness almost equal to the grain size # 80 and the surface roughness almost the same as the grain size # 120.

When grinding ceramics, cemented carbides, metal materials, glass, etc. other than PCD, a wheel in which coarse diamond and chips made of finer diamond are mixed and fixed is used. In general, the grinding characteristics appear remarkably. That is, wheel characteristics such as excellent sharpness and improved processing efficiency but rough surface roughness and large chipping can be obtained. However, in the case of PCD grinding, unlike the general concept of grinding, the hardness of diamond abrasive grains and PCD is almost the same, so that chips containing coarse diamond and chips containing fine diamond must be mixed. Thereby, good surface roughness can be obtained without lowering sharpness.

[0017]

According to the present invention, a vitrified bonded diamond wheel having excellent grinding characteristics having both the sharpness of coarse-grained diamond and the good surface roughness of fine-grained diamond in grinding of PCD.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuki Morita 2-80 Hokita-cho, Sakai-shi, Osaka Osaka Diamond Mondro Kogyo Co., Ltd.

Claims (1)

[Claims] 1. A vitrified bond diamond wheel having a diamond chip bonded with a vitreous or ceramic bond material fixed to a base metal, the diamond chip including coarse diamond abrasive grains having an average particle diameter of 100 μm to 1500 μm. And the average particle size of 30
% And 70% or less of diamond chips containing fine diamond abrasive grains are fixedly mixed and have an average particle diameter of 100%.
The number of diamond chips containing coarse diamond abrasive grains of not less than μm and not more than 1500 μm is 40
% To 80%, and used for grinding a polycrystalline diamond sintered body.