JPH0757473B2 - Super Abrasive Wheel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention balances excellent grinding ability and grindstone life even for difficult-to-cut materials such as fine ceramics and special steel that are difficult to grind efficiently. It relates to a superabrasive grindstone that has a good fit.

<Prior Art> Under a grinding condition in which a cutting edge of a grindstone can be maintained for a long time, a metal-bonded superabrasive grindstone having a long grindstone life is widely used because of its advantageous tool cost. However, for difficult-to-cut materials, it is difficult to maintain the cutting edge, and the frequency of dressing work for regeneration is high.
The dressing time required for each operation is long, which not only increases the tool cost but also significantly lowers the grinding efficiency.

In order to solve this problem, a vitrifide superabrasive grindstone has been developed and used. This grinding wheel, which uses a ceramic bond, offers significant improvements in cutting edge durability, dressing problems, and grinding efficiency. However, the life of the grindstone is inevitably inferior to that of the metal bond grindstone, the tool cost becomes high, and the total cost including the efficiency is not necessarily advantageous, and it has not been possible to satisfy customers.

<Problems to be Solved by the Invention> The present invention solves the above-mentioned problems, namely, the unbalanced grinding life of the grinding ability of the conventional metal bond superabrasive grindstone or the conventional vitrified superabrasive grindstone. Is what you are trying to do.

<Means for Solving Problems> In the present invention, metal powder 5 is added to 100 parts by volume of a ceramic binder such as glassy powder having a melting point of 500 to 1000 ° C.
In a superabrasive grindstone in which superabrasive grains such as diamond or cubic boron nitride (CBN) are bonded by a binder mixed with ˜30 parts by volume, the apparent density ratio of the grindstone is 70%. The above is a vitrified superabrasive grindstone characterized by the above, and the present invention has made it possible to solve the above problems.

In the present invention, a ceramic-based binder such as glass powder having a relatively low melting point of 500 to 1000 ° C. is used as a base. If the melting point of the binder is less than 500 ° C., the force for holding and holding the abrasive grains is weak, and if it exceeds 1000 ° C., the oxidation of the abrasive grains or the reaction with the bond becomes significant, and the original grinding action of the abrasive grains is lost.

In the present invention, when the amount of the metal powder is less than 5 parts by volume with respect to 100 parts by volume of the ceramic binder, the effect of improving the life of the grindstone is small, and when it exceeds 30 parts by volume, the reduction of the grinding efficiency becomes remarkable.

When the ratio of the apparent density to the true density of the grindstone is called the apparent density ratio, in the present invention, the apparent density ratio is
It is necessary that the grindstone be shaped so that it is 70% or more. If the apparent density ratio is less than 70%, the strength and life of the grindstone are insufficient for grinding difficult-to-cut materials. The “true density” means a value obtained by dividing the total mass of the individual materials constituting the grindstone by the volume of each material. Here, the volume of each material is a value obtained by dividing the weight of each material by the specific weight of each material. The apparent density is a value obtained by dividing the mass of the grindstone by the apparent volume of the grindstone.

Explaining the state of the grindstone in detail, the metal powder and the superabrasive grains are uniformly dispersed in the ceramic binder as a base. The ceramic binder is in a state of being once melted or sintered, and firmly bonds the superabrasive grains and the metal powder. In the grindstone in such a state, the wear of the bond due to the cutting chips progresses moderately, while excessive wear is suppressed, so the durability of the cutting edge is good and the balance between the grinding ability and the grindstone life is greatly To be improved.

<Examples> Grinding test samples were prepared under the following manufacturing conditions.

(1) Raw material Ceramic binder: Borosilicate glass powder Metal powder: -325 mesh Cu-10% Su alloy powder Super abrasive grain: # 140 Diamond abrasive grain (2) For 100 parts by volume of compounding ceramic binder, Metal powder 0,5,10,
Bonds in which 20, 30 and 40 parts by volume were mixed and bonds composed only of metal powder without a ceramic binder were used, and the concentration of diamond abrasive grains was set to 100.

(3) Molding Fill the graphite mold with the above mixture and pressurize the graphite mold with an electric current to heat it at the same time and keep it at 650 ° C for 5 minutes to maintain the outer diameter 25 mm, inner diameter 6 mm and thickness 5 mm. It was molded into a predetermined size.

(4) Apparent density ratio The apparent density ratio is 60%, 7 when molded to the above specified dimensions.
The weight calculated so as to be 0% and 95% was taken as the filling amount at the time of molding.

(5) Sample Preparation A 5.8 mm shaft was bonded to the center of the ring-shaped molded product obtained in (1) to (4) to prepare a test sample of a grindstone with a shaft.

A grinding test was performed on the test sample manufactured according to the above procedure and the conventional product under the following conditions.

(1) Grinding wheel shape: 25 mm diameter x 5 mm thick whetstone with a shaft (2) Grinding wheel rotation speed: 26,000 rpm (peripheral speed 2,000 m / mim) (3) Testing machine: Portable grinder (4) Motor load current: 1.5 amps (5) Workpiece: Silicon carbide (6) Processing time: 4 minutes (7) Grinding fluid: Water-soluble coolant From the grinding test, the weight reduction of the workpiece and the grindstone was obtained to obtain the grinding efficiency and the grinding ratio. Further, in order to compare the balance between the grinding efficiency and the grindstone life, the product obtained by multiplying the grinding capacity by the grinding ratio is displayed.

The results of the grinding test are shown in Table 1.

The results in Table 1 show that the present invention improved the grinding efficiency (ability) as compared with the conventional metal bond grindstone, and the grinding ratio (life) as compared with the conventional vitrified grindstone. The product of (A) and grinding ratio (B) is
Compared to any of the conventional whetstones, it shows extremely high numerical values,
It is shown that the unbalance between the grinding ability of the conventional grindstone and the grindstone life is greatly improved by the present invention.

Further, with respect to the grindstone samples shown in Table 1, a single stone dresser or a multi-stone dresser was used for trueing, and the wear states of the grindstone and the dresser were examined to examine the possibility of trueing by the dresser.

In the present invention, a single stone dresser can be used for a molded product having an apparent density ratio of 70%, and a multi-stone dresser can be used for a molded product of 95%. On the other hand, with the conventional metal-bonded diamond grindstone, both the single stone and the multi-stone dressers are worn out and cannot be used.

As the ceramic binder used in the present invention, borosilicate glass powder as well as aluminosilicate glass powder are suitable because of their low linear expansion coefficient.

As the metal powder, Cu-10% Sn alloy powder and C
A relatively soft metal such as u, Ni, Fe, Co or Ni-Sn, Co-Sn, Ni-Cu, or an alloy of -325 mesh fine powder is suitable. In this embodiment, diamond abrasive grains are exemplified as the superabrasive grains, but cubic boron nitride abrasive grains also show the same tendency.

<Effects of the Invention> According to the superabrasive grindstone of the present invention, even for difficult-to-cut materials,
Not only does it show excellent performance and good balance in grinding ability and wheel life, but it can also be used with a single stone dresser or multi-stone dresser, which is not possible with a metal bond grindstone, during touring. Further, the ceramic binder and the metal powder added to the superabrasive grain mixture system act as a lubricant during molding and have the effect of lowering the molding temperature, while at the same time imparting thermal conductivity and electrical conductivity, the grinding stone Is easy to manufacture.

Claims (1)

[Claims] 1. A grindstone in which superabrasive grains are bonded by a binder obtained by mixing 5 to 30 parts by volume of metal powder with 100 parts by volume of a ceramic binder having a melting point of 500 to 1000 ° C. A superabrasive stone with an apparent density ratio of 70% or more.