JPH0251345A - Manufacture of carbon brush - Google Patents

Abstract

PURPOSE:To reduce abrasion of brush by mixing abrasives having grain size smaller than 50mum, molybdenum disulfide powder and binder solution to produce granular particles then mixing 1-10wt.% of the granular particle with graphite powder mixed with binder thereafter molding and burning the mixture. CONSTITUTION:Molybdenum disulfide or tungsten disulfide having average grain size smaller than 5mum is generally employed although the grain size is not limited. Granular particles of abrasives and molybdenum disulfide or tungsten disulfide are mixed with proper quantity of binder then the mixture is classified and the mixture having grain size conditioned in the range of 75-300mum is employed. There is no restriction in the mixing ratio of the abrasives and molybdenum disulfide or tungsten disulfide and the mixing ratio can be conditioned according to the degree of the skin film formed on the communicator face. The granular particles of the abrasives and the lubricant are added by 1-10wt.% to the graphite powder.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing carbon brushes for rotating electric machines, particularly for small-sized rotating electric machines.

(Prior art) In order to maintain the sliding contact of carbon brushes (hereinafter referred to as brushes), a method for removing an excessively formed skin film on the commutator surface is disclosed in Japanese Patent Publication No. 39-16363. Amorphous silica and alkali metals and alkaline earth metals in the brush.

containing metals that promote silica crystallization, such as manganese, aluminum, bismuth, etc., and
There is a method of manufacturing a brush by heat treatment at a temperature of about 0 to i,00°C. In addition, it was developed under the Japanese Patent Publication No. 58-5 as a product that prevents the formation of harmful commutator/surface films, provides an appropriate film preparation effect, and provides stable rubbing characteristics even under high-speed rotation.
As shown in Japanese Patent No. 8787, a binder and 0.5 to 5% by weight of aluminum powder are added to graphite powder, and 350%
There is a brush that is treated at a temperature of 0.degree. Furthermore, for the same purpose, as shown in Japanese Patent Publication No. 60-13382, a method for manufacturing brushes involves adding a binder, aluminum powder, and silicon carbide powder to graphite powder and heat-treating the mixture at a temperature of 150°C or higher and 350°C or lower. is proposed.

(Problems to be Solved by the Invention) Although the brush disclosed in Japanese Patent Publication No. 39-16363 is effective in removing the surface film of the commutator.

In rotating electric machines that rotate at high speed and have a large capacity, scratches from crystallized silica occur, making the sliding contact state unstable.
Also, Special Publication No. 58-58787 and Special Publication No. 60-1
Although the brush disclosed in Japanese Patent No. 3382 is effective in terms of stability of sliding contact, it cannot be said to be effective in removing the surface film of the commutator for large-capacity rotating electric machines.

The present invention prevents the excessive formation of a skin film on the commutator surface due to the power up of rotating electric machines in recent years, and provides a long-life rotating electric machine with less brush wear even in high-speed rotation and large capacity rotating electric machines. It provides a brush.

(l!?!An unsuccessful means to solve the problem) The present invention produces particles of 75 to 300 μm by kneading two abrasives with a particle size of 50 μm or less, powder of molybdenum disulfide or tungsten disulfide, and a solution of a binder. 1 to 1 to the graphite powder to a kneaded product obtained by kneading and pulverizing graphite powder and a binder.
The present invention relates to a method for manufacturing a brush, which comprises mixing 10% by weight of the particles, molding and firing.

The graphite powder used in the present invention is usually artificial graphite obtained by graphitizing petroleum-based or coal-based coke, natural graphite, quiche graphite, pyrolytic graphite, etc., and the particle size of the binder and the crosstalk successor amount are used. crushed into There are no particular restrictions on the particle size of the graphite powder or the particle size of the graphite powder mixed with the binder and then crushed.

Novolac phenolic resin is used as a binder for graphite powder,
Thermosetting resins such as resol type phenolic resins and epoxy resins, tar pitch, coal tar, etc. are used.

The brush according to the present invention uses, in addition to the above-mentioned raw materials, granulated particles obtained by granulating a lubricant powder of molybdenum disulfide or tungsten disulfide with a binder solution. The binder for granulation is preferably a thermosetting resin, and is used together with a solvent soluble in the resin.

The abrasives used in the present invention include r-alumina, α-alumina,
Powders of silica, silicon carbide, chromium oxide, etc. with a diameter of 50 μm or less are used. Further, although there is no limit to the particle size of the powder of trisulfide disulfide or tungsten disulfide, those having an average particle size of 5 μm or less are generally used.

When the abrasive material used in the present invention exceeds 50 .mu.m, the abrasive action becomes too strong, and if there are scratches on the commutator surface, step wear occurs.

The particles of the abrasive and molybdenum disulfide or tungsten disulfide used in the present invention are mixed with an appropriate amount of a binder solution and then classified to have a particle size in the range of 75 μm to 300 μm. If the thickness is less than 75 μm, it is difficult to obtain the effect of removing the skin film on the commutator surface and the lubricating effect of molybdenum disulfide or tungsten disulfide. If the diameter of the particles exceeds 300 μm, the insulator will be unevenly distributed in the brush, and the effect of removing excess skin film will be uneven, making band-like streaks more likely to occur on the commutator surface. .

The blending ratio of the abrasive and molybdenum disulfide used in the present invention with tungsten disulfide is not limited and can be adjusted as appropriate depending on the degree of the surface film formed on the commutator surface.

The amount of abrasive and lubricant particles added is 1 to graphite powder.
~10 weight i-s, and if it is less than 1% by weight, there is no effect as in the case where the particle size is less than 75 μm, and 101 [
If it exceeds i%, the polishing action becomes excessive, the sliding contact condition worsens, and the generation of sparks increases.

(Example) Hereinafter, one aspect of the present invention will be explained in detail.

Example 1 α-Alumina 10 with a maximum particle size of 50 μm and an average of 15 μm
After mixing parts by weight with 90 parts by weight of molybdenum disulfide having an average particle size of 5 μm, HP-208 was added to the mixture as a binder.
20 parts by weight of NK (novolac phenol resin 9, manufactured by Hitachi Chemical Co., Ltd., trade name) and 20 parts of methanol!
100 μm to 250 μm.
Particles with a particle size of μm were obtained. 70 parts by weight of pitch coke-based artificial graphite powder with an average particle size of 20 μm was added with the above H
After adding 30 parts by weight of P-208NK and 30 parts by weight of methanol and kneading at 55°C, the mixture was pulverized to obtain a kneaded product with a particle size of 100 μm or less. 1. Next, the above-mentioned particles were added to the graphite powder by 0.5%.
The mixture was added to the kneaded powder at a rate of ~15 weight fL-, and the mixture was molded at "-2t/Cm" and fired at 700°C to obtain plan materials with eight types of added amounts of particles.

Example 2 20 parts by weight of γ-alumina with a maximum particle size of 50 μm and an average particle size of 30 μm and tungsten disulfide 80i-i with an average particle size of 5 μm
100 μm to 2 by the same method as in Example 1 using
Particles of 50 μm were obtained, and the particles were added to and mixed with kneaded powder at a ratio of 1 to 15 weight percent based on graphite powder in the same manner as in Example 1, and molded and fired in the same manner as in Example 1. Brush materials with eight types of particle addition amounts were obtained.

Example 3 Using 5 parts by weight of silicon carbide powder with a maximum particle size of 50 μm and an average of 10 μm, and 95 parts by weight of molybdenum disulfide with an average particle size of 5 μm, particles of 100 μm to 250 μm were prepared in the same manner as in Example 1.
m particles were obtained, and this was mixed with graphite powder by 1 to 15 times fn.
% to the kneaded powder, molded and baked in the same manner as in Example 1 to obtain eight types of brush materials.

Comparative Example 1 A brush material was obtained in the same manner as in Example 1 except that α-alumina having an average particle size of 85 μm was used as the abrasive material.

Comparative Example 2 A brush material was obtained in the same manner as in Example 3, except that silicon carbide powder with an average particle size of 60 μm was used as the abrasive material.

Comparative Example 3 In the same manner as in Example 1, an abrasive material and a lubricant were mixed with a resin solution and then classified to obtain granulated powder of less than 75 μm and granulated powder of more than 250 μm. The mixture was added to the kneaded powder so as to have a weight of 10 parts, and the same procedure as in Example 1 was carried out to obtain a brush material.

A brush was processed from the brush materials obtained in the above Examples and Comparative Examples, and the ACI OOV was 1kW and the rotation speed was 26.00 O.
A comparative test of brush wear was conducted using an alternating current commutator motor at rpm. Figure 1 shows the amount of particles added to the abrasive and lubricant and the brush wear for the brushes obtained in the examples.
FIG. 2 similarly shows the relationship between the amount of abrasive and lubricant particles added and the amount of brush wear for the carbon brush obtained in the comparative example.

As is clear from Fig. M1 and Fig. 2, brushes to which 1 to 10% by weight of abrasive and lubricant particles were added had less brush wear; If the amount is less than % by weight, there is no effect in removing the excessively produced skin film on the commutator surface.

4- As time passes, the coating becomes excessive and sparks become larger, resulting in increased brush wear. Also, the amount added is 10f
If the amount exceeds the fi limit, unstable sliding will occur due to excessive abrasive action and sparks will become large.

Added particles may fall off, increasing brush wear.

(Effects of the Invention) The brush obtained by the present invention has both the film-adjusting action of the abrasive and the lubricating action of the lubricant, prevents excessive film from forming on the commutator surface of single-rotation electric machines, and prevents high temperatures. It has a lubricating effect underneath, and has a long life even in large-capacity rotating electric machines.

[Brief explanation of the drawing]

FIGS. 1 and 2 are graphs showing the relationship between the amount of abrasive and lubricant particles added to the brush and the amount of wear of the brush.

Claims (1)

[Claims] 1. An abrasive with a particle size of 50 μm or less, molybdenum disulfide or tungsten disulfide powder, and a binder solution were kneaded to obtain particles of 75 to 300 μm, and graphite powder and a binder were kneaded and crushed. A method for manufacturing a carbon brush, which comprises mixing kneaded powder with 1 to 10% by weight of the particles based on the graphite powder, molding and firing.