JPS6257872A - Sintered metal bond grinding wheel - Google Patents

Abstract

PURPOSE:To increase the holding force of a hard abrasive grain, give wear resistance, reduce grinding resistance, and improve cutting quality by forming plural layers around a hard abrasive grain in a metal bond phase. CONSTITUTION:First, a metal coating 2 of high melting point is formed on the surface of a diamond abrasive grain 1 and, then, a metal coating 3 of low melting point is formed on the metal coating 2, to make a composite abrasive grain 4. This composite grain 4 is charged into a mold while being vibrated, and then, subjected to cold pressing to increase the charging density of the diamond abrasive grain 1, and subjected to hot pressing to be sintered, obtaining a metal bond grinding wheel. The holding force of the diamond abrasive grain 1 can be increased due to the existence of the metal coating 2 of high melting point, while fusing between the composite abrasive grains 4 at the time of sintering can be easily carried out due to the existence of the metal coating 3 of low melting point. Thereby, the bonding strength of the metal bond grinding wheel is increased, the wear of the center part between the hard abrasive grains in which the metal coatings 3 of low melting point exist, is increased facilitating the escape of chips, and improving a cutting quality.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a meta
HノV KrCy 7:l= こh'A 1. −
M K< 16 (nm Regarding Yusakugi Keita's sintered metal bond grinding wheel.

[Prior Art] As is well known, grinding wheels such as diamond grinding wheels and CBS (cubic boron nitride) grinding wheels are used for grinding hard and brittle materials such as cemented carbide, ceramics, and ferrite. This type of grindstone is made by mixing hard abrasive grains such as diamond abrasive grains or CBN abrasive grains with a binder such as resinoid bond, metal bond, or hydrified bond, molding the mixture, and then sintering the mixture.

Products using metal bond as a binder have high abrasive retention and wear resistance, so they are used for precision cutting of semiconductors, ceramics, etc., stone cutting, and grinding of cemented carbide tools.

[Problems to be Solved by the Invention] Incidentally, the metal bond grindstone produced by the conventional mixing method described above has the following drawbacks.

(1) In the mixing method, uniform mixing cannot be achieved due to differences in abrasive grain size and specific gravity, resulting in uneven distribution of hard abrasive grains in the grindstone and relatively low concentration. Here, the degree of concentration is
It shows the proportion of abrasive grains in an abrasive grain cake consisting of abrasive grains and a binder, and an abrasive grain ratio of 25Vo1% is defined as a concentration of 100.

(2) The component distribution of the metal bond phase is macroscopically non-uniform, causing local wear during use.

(3) It is difficult to manufacture thin, high-strength cutting blades due to insufficient strength of the metal bond layer due to poor sinterability.

(4) The force for holding the diamond abrasive grains is small, and the grinding wheel wear is large.

This invention was made against this background, and has a uniform distribution of hard abrasive grains and a high concentration, resulting in high abrasive grain retention, high bond phase strength, and excellent resistance. The purpose is to provide sintered metal bond grinding wheels.

"Ideas that formed the basis of the invention" In order to solve the above problems, we conducted research based on the following ideas.

(1) The metal that forms the metal bond phase is used as a hard abrasive grain.
According to the method of sintering the inverted composite low grains, it is possible to obtain a metal bond grindstone in which the distribution of hard low grains is uniform and highly concentrated, and the component distribution of the metal bond phase is macroscopically uniform.

(2) Furthermore, by forming the composite low-grain metal layer into multiple layers, the microscopic component distribution of the metal bonded orange can be adjusted.

(3) Therefore, a significant improvement in the properties of the metal pond phase can be expected.

[Means for Solving the Problems] This invention was born from the above research, and its gist is that a plurality of layers are formed around hard abrasive grains in a metal bond phase. In addition, if the innermost layer of multiple layers is
It is characterized by a relatively high melting point compared to other layers.

Furthermore, the outermost layer of the plurality of layers is characterized in that it has a relatively low melting point compared to the other layers.

[Function] According to the above means, (1) In the obtained metal bond grindstone, 1iil!
The distribution of the abrasive grains can be made uniform and highly concentrated, but the component distribution of the metal bond phase is macroscopically uniform.

In addition, the content of hard abrasive grains is preferably 5 to 70 VO1%, and if it is less than 5%, the grinding effect will be small, and if it exceeds 70%, the abrasive grain retention will be weak.

(2) Since a metal layer with a relatively high melting point exists near the hard abrasive grains, the holding power of the abrasive grains is high. During grinding, the temperature of the grinding wheel rises, and in particular, the abrasive grains in contact with the workpiece material and their vicinity become high temperatures. , it is possible to achieve even higher abrasive grain retention.

(3) On the other hand, a metal layer with a relatively low melting point is formed on the outermost layer of the composite abrasive grains that are the raw material powder, and welding between the composite abrasive grains easily progresses during sintering, so the resulting metal bonded abrasive In the grinding wheel, the wear in the center between the hard abrasive grains, where the bond strength is high and the metal layer with a relatively low melting point exists, is greater than the wear in the vicinity of the hard abrasive grains. It becomes sharper to help escape.

Stone has high retention power and bond strength of hard, low-grain particles, and the component distribution of the bond phase is macroscopically uniform, so there is no unevenness in wear, so it is highly durable. It has a high degree of concentration, allows smooth escape of grinding debris from the worn bond phase, and has good sharpness.

[Example code] The present invention will be explained in detail below.

Example 1 Diamond abrasive grain 1 (# 140/170) in Figure 1
First, a Ni-10 wt% W coating (Fukel-Tungsten alloy 2) coating@2 is formed by electroless plating to form a first layer, and a Cu (copper) coating 3 is formed on the N1-W coating@2.
was formed by electroless plating to form the second layer. In this way, the diamond abrasive grains 1 are covered with two layers of metal coating 2.3, forming composite abrasive grains 4. Here, the composition of the obtained composite low grain 4 is diamond 55Vo1%, N1-
WIOVo1% and Cu35Vo1%.

1r-r-L- to mouth 1a with Ishisho knot 4 times: After putting it in, cold press (5 ton/cm')
The packing density of the diamond abrasive grains 1 was increased by
5 minutes) and sintered to produce a metal bond grindstone.

The created metal bond grindstone has a grindstone layer with a width of 6 m and a thickness of 3 mm formed around the outer periphery of a steel core metal, the concentration degree is 220, and the structure of the grindstone layer is the second one. As shown in the figure.

In this figure, the nearest layer of diamond abrasive grain 1? Here, an N1-W layer 6 is formed, and on the outside thereof, N1-W and C
There is a diffusion layer 7 with U, and a Cu layer 8 in the outermost layer, that is, at the junction with the adjacent grain.

The metal bond grindstone according to Example 1 and the metal bond grindstone according to the conventional method were compared in a grinding test. Here, the comparative product was prepared by mixing diamond abrasive grains and metal powder to have the same composition as Example 1, and then molding it.
A grindstone having the same shape as in Example 1 was finished by cold pressing and hot pressing. In the grinding test, glass was used as the work material, and the grinding conditions were as follows: peripheral speed of the grinding wheel was 150
0m/min, depth of cut 0.7mm, table feed lO
m/win, table cloth feed 2 mm/pass
, wet type.

As a result of the grinding test, the grinding ratio of the diamond whetstone according to Example 1 was 15,000, which was 5 times higher than that of the comparative product. I didn't want to climb it, the strength of the whetstone was low, and when I rubbed it with my fingers, the diamond grains fell off.

In addition, the above metal covering ri! 2 of Ni-W, Co-W(
1: '7 Baltic tungsten alloy),
64, the results were similar to 3. [Example 2] The surface of Diamond Low Grain 1 (#140/170) was coated with W by CVD, and then Ni was coated with electroless plating, Finally, Sn was coated by electroplating to create composite abrasive grains. This composite abrasive grain was sintered in the same process as in Example 1 (cold press 5 ton/cm', hot press 800°C, 350 kg/cm'', 5 minutes) to produce a metal bonded grindstone with a concentration of 250. Noko.

The shape of the grindstone was the same as in Example 1, and the structure of the grindstone layer was as shown in FIG. That is, diamond abrasive grain l
A W layer 9 was present in the vicinity of the W layer 9, and an intermetallic compound 10 of Ni and Sn was formed around the W layer 9, thereby bonding the composite abrasive grains.

When this grindstone was subjected to a grinding test under the same conditions as in Example 1, the grinding ratio was 17,000, and the grinding resistance was small and good. When the surface of the grindstone after the grinding test was observed with a scanning electron microscope, it looked as shown in FIG. 4.

That is, the W layer 9 remained in the vicinity of the diamond abrasive grains 1 and firmly held the diamond abrasive grains 1, and the Ni-8n intermetallic compound 10 present around the W layer 9 was worn out.

In this way, the diamond abrasive grains 1 were sufficiently exposed and the Ni-3n layer between the composite abrasive grains was worn, so that the grinding debris could escape easily and the grinding resistance was reduced.

[Effects of the Invention] As explained above, the metal boron)'' according to the present invention
Kasuri-A is a metal layer with a relatively high melting point near the diamond abrasive grains, and a metal layer with a relatively low melting point outside of the diamond abrasive grains17, forming a bond phase. It has a high ability to hold particles and is wear resistant.
In addition, the grinding resistance is low and good sharpness can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the structure of a composite abrasive grain according to a first embodiment of the present invention, FIG. 2 is a schematic cross-sectional view showing the structure of a grinding wheel layer according to the same embodiment, and FIG. FIG. 4 is a schematic cross-sectional view showing the structure of the grindstone layer. FIG. 4 is a schematic cross-sectional view showing the surface structure of the grindstone layer after grinding according to the same embodiment. l...Diamond abrasive grain (hard abrasive grain), 2.3
...Metal coating, 4...Composite abrasive grain, 6,7
, 8, 9.10...metal layer.

Claims (3)

[Claims] (1) A sintered metal bond grindstone characterized in that a plurality of layers are formed around hard abrasive grains in the metal bond phase. (2) The sintered metal bond grindstone according to claim 1, wherein the innermost layer of the plurality of layers has a relatively high melting point compared to other layers. (3) The sintered metal bond grindstone according to claim 1 or 2, wherein the outermost layer of the plurality of layers has a relatively low melting point compared to other layers.