JPH05190249A - Manufacture of carbon brush - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a carbon brush for a dynamo-electric machine having a stable sliding characteristic even at a high rotational speed by preventing a skin film of commutator surfaces from being excessively generated. CONSTITUTION:In a method for manufacturing a carbon brush, relating to graphite powder of main material, 0.25 to 5.0wt.% aluminum (Al) powder, 0.05 to 1.0wt.% titanium powder and thermosetting resin are added with an Al powder amount in proportion to a Ti powder amount, and after mixing and molding, heat treatment is applied at 150 to 300 deg.C temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a carbon brush used in a rotary electric machine, particularly a small rotary electric machine.

[0002]

2. Description of the Related Art With the downsizing and speeding up of rotating electrical machines, the friction characteristics of brushes become unstable due to machine vibration and the like, and rectification tends to deteriorate. As a countermeasure against this, in order to keep the sliding contact of the carbon brush good by removing the excessively generated film on the commutator surface, in Japanese Patent Publication No. 39-16363, amorphous silica and alkali metal are contained in the brush. 700 to 1000 ° C., containing an alkaline earth metal and a metal such as Mn, Al, Bi, Ni having a crystallization promoting action on silica.
It is heat treated in. Further, in order to prevent harmful commutator skin layer from being produced and to perform proper film adjusting action and to obtain stable rubbing characteristics even at high speed rotation, Japanese Patent Publication No. 58-5878
According to Japanese Patent Laid-Open No. 7-75, 0.5 to 5.0 wt% of Al powder is contained in a brush and heat treatment is performed at a temperature of 350 ° C. or lower. On the other hand, in Japanese Patent Publication No. 60-13382, 0.5 to 0.5
5.0 wt% Al powder and 0.5-5.0 wt% SiC
Incorporate powder, heat treat at a temperature of 150-350 ° C,
The high resistance excessive film that is likely to be produced by the Al powder is adjusted by the polishing property of the SiC powder, and the increase in the friction coefficient due to the polishing property of the SiC powder is suppressed by the film forming action of the Al powder to keep the sliding state stable.

[0003]

[Problems to be Solved by the Invention]
Although the brush according to Japanese Patent No. 39-16363 has an action of removing the film on the commutator surface, the polishing action of silica is so strong that the friction coefficient and its variation are likely to be large, which causes a problem of reducing the efficiency of the rotating electric machine. .. In addition, Japanese Patent Publication Sho 58-5878
The brushes of Japanese Patent Publication No. 7 and Japanese Patent Publication No. 60-13382 have an effect of lowering the friction coefficient, but it is difficult to say that the efficiency of the electric motor and the life of the brush are sufficient from the performance of the brush required today. That is, the current rotation speed is 30000rp
Electric motors for electric vacuum cleaners and the like that are driven at high speeds of m or higher have problems of low motor efficiency, increased brush wear, and short life.

According to the present invention, the friction coefficient and its fluctuation are small, and the contact voltage drop is small, that is, it prevents excessive formation of the surface film on the commutator surface, and has stable rubbing characteristics even at high speed rotation. At the same time, a method of manufacturing a carbon brush for a rotating electric machine having a long life is provided.

[0005]

According to the present invention, 0.25 to 5.0% by weight of Al powder and 0.0% by weight of Ti powder are used with respect to the main raw material graphite powder.
5 to 1.0% by weight and the thermosetting resin, the amount of Al powder and Ti
After adding in proportion to the amount of powder, mixing and molding, 150 ~
The present invention relates to a method for manufacturing a carbon brush that is heat-treated at a temperature of 300 ° C.

In the present invention, the main raw material of the graphite powder is artificial graphite obtained by graphitizing purified natural graphite, petroleum-based coke, coal-based coke, etc., pyrolytic graphite,
It is a powder such as quiche graphite, and the particle size is not particularly limited.
The ash content is preferably 0.5% by weight or less, because if the amount of ash is large, the rubbing characteristics become unstable when a brush is used, or scratches are generated on the commutator. The thermosetting resin used as the binder is not particularly limited, but a phenol resin or an epoxy resin is preferable.

There are granular and scale-like Al powders,
Either of them may be used, but the particle size is preferably 200 mesh or less. If the particle size is large, it tends to be unevenly distributed in the brush. The Ti powder includes mechanically pulverized ones and spherical ones produced by an atomizing method, and either of them may be used. Particle size is 250
A mesh or less is preferable. If the particle size is large, the abrasiveness becomes strong, the friction coefficient increases, and the rubbing characteristics become unstable.

The amounts of Al powder and Ti powder added are 0.25 to 5.0% by weight and 0.
It is set to 05 to 1.0% by weight. If the added amount of Al powder and Ti powder exceeds this upper limit value, the abrasiveness becomes strong, the friction coefficient increases, and the sliding characteristics become unstable. If the addition amount is less than the lower limit value, the film adjusting action becomes insufficient and an excessive film is formed, which also causes an increase in the friction coefficient and the contact voltage drop. Further, when either the Al powder or the Ti powder is mixed in a large amount or in a small amount, the respective characteristics are emphasized and the same troubles as described above are likely to occur. Therefore, in the present invention, the amounts of the Al powder and the Ti powder are proportionally added. .. That is, when the amount of Al powder is small, the amount of Ti powder is decreased and the powder is added in a good balance.

The graphite powder, the Al powder and the Ti powder in the above amounts, and the thermosetting resin are mixed to form a molding powder. When the resin is solid, it is appropriately pulverized and mixed by a usual powder mixer, and when the resin is liquid, an appropriate solvent is added, and the mixture is kneaded with a known kneader or the like to remove the solvent and then pulverized to obtain a molding powder. To be done. The molding powder is molded by a known method, heat-treated at a temperature of 150 to 300 ° C. to be a brush material, and this is processed and assembled to a predetermined specification to be a brush.

[0010]

EXAMPLES Next, examples of the present invention will be described. To 100 parts by weight of the main raw material of pitch coke artificial graphite powder having an ash content of 0.1% by weight pulverized to 200 mesh or less, granular Al powder of 200 mesh or less and spherical Ti powder of 250 mesh or less were added in the combination shown in Table 1. In addition, as a binder, a bisphenol type epoxy resin (produced by Yuka Shell Epoxy Co., Ltd.,
Maleic anhydride was added as a powder of Epicoat 1002) and a curing agent for the resin, and the mixture was put into a Warner type kneader and mixed, and then molded at a pressure of 1 t / cm ² . Then, heat treatment was carried out at a temperature of 250 ° C. to obtain 11 kinds of brush materials, which were processed and assembled to obtain brushes.

[0011]

[Table 1]

The friction coefficient and the contact voltage drop of the 11 kinds of brushes obtained in the examples were measured. The results are summarized in Fig. 1. The sliding state during the measurement was stable.

As is apparent from FIG. 1, 0.25 to 5.0 parts by weight of Al powder and 0.0% by weight of Ti powder within the scope of the present invention.
The brush of the embodiment having an amount of 5 to 1.0 parts by weight has a coefficient of friction of 0.16 to 0.18 and a contact voltage drop of 0.
It is 6 to 1.0V. On the other hand, in the comparative examples where Al powder and Ti powder were not added at all and the addition amount exceeded the upper limit, the friction coefficient was 0.21 or more and the contact voltage drop was 1.6 V or more. The brush to which an appropriate amount of Ti powder and Ti powder were added improved the friction coefficient by about 20% and the contact voltage drop by about 60% as compared with the brush not added at all. As a result, electrical loss and friction loss (mechanical loss) can be reduced, and since the sliding state is stable, the rectification performance can be maintained well. From this result, it was confirmed that the area where the brush rubbing characteristics were stable was within the shaded area in FIG.

[0014]

According to the present invention, the generation of the skin layer on the commutator surface of the rotating electric machine is excessive due to the synergistic effect of the good slushing property of the main raw material graphite and the proper film adjusting action of the Al powder and the Ti powder. It is possible to provide a good brush even at high speeds by preventing the occurrence of the above phenomenon, keeping the sitting property of the brush good, and reducing the friction coefficient and its fluctuation.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the amount of Al powder and Ti powder added and the friction coefficient and contact voltage drop.

FIG. 2 is a graph showing a stable region of abrading characteristics in the amounts of Al powder and Ti powder added.

Claims (1)

[Claims] 1. An aluminum (Al) powder in an amount of 0.25 to 5.0% by weight and a titanium (Ti) powder in an amount of 0.1 to 0.5% by weight relative to the main raw material graphite powder.
05-1.0 wt% and thermosetting resin were added in proportion to the amount of Al powder and the amount of Ti powder, and after mixing and molding, 15
A method for producing a carbon brush, which comprises performing heat treatment at a temperature of 0 to 300 ° C.