JPH0449833A - Laminated brush - Google Patents

Abstract

PURPOSE:To prevent break in the baking process to extend the expected life by forming a low resistance part with a low resistance material mixing copper powder ensuring easy plastic deformation and molding characteristic and forming a high resistance part with a high resistance material mixing copper powder ensuring difficulty in plastic deformation and deteriorated molding characteristic. CONSTITUTION:A laminated brush 1 allows mixing of copper powder ensuring easy plastic deformation and ensuring excellent molding characteristic for a low resistance material to form a low resistance part 2 and also mixing of copper powder ensuring difficulty in plastic deformation and deteriorated molding characteristic. Therefore, in the case where a low resistance material including a large quantity of copper and a high resistance material including a small quantity of copper are simultaneously pressurized for the molding, the difference of uniformity of structures between the low resistance part and high resistance part becomes smaller in comparison with a conventional integrally molded laminated brush and rather uniform structure can be obtained. As a result, break in the baking process can be prevented and reduction of life expectancy can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a laminated brush used in rotating electric machines such as generators and electric motors.

[Prior Art] Conventionally, in order to prevent sparks generated from brushes that come into sliding contact with a commutator of a rotating electrical machine, for example, Japanese Patent Application Laid-Open No. 59-660
No. 82 (and other publications such as JP-A-50-27007, JP-A-61-73550, JP-A-62-61284, and JP-A-62-71453) discloses two types of resistance. A laminated brush composed of layers is used.

This laminated brush is made by separately molding a low resistance part with a high copper content and a high resistance part with a low copper content, and then bonding them together with an adhesive or the like, or by
No. 4 proposes a technique of integrally molding a low resistance part and a high resistance part in order to prevent the low resistance part and the high resistance part from peeling off. In this method, for example, powders having different amounts of copper are filled into molds, pressure molded, and fired at a predetermined temperature to obtain a molded product.

[Problems to be Solved by the Invention] However, when the low-resistance part and the high-resistance part are integrally molded, since powders having different amounts of copper are molded at the same time, the structure between them becomes non-uniform. In other words, as the amount of copper, which is less plastically deformable than graphite, increases, higher pressure is required to obtain a uniform dense structure during molding. (pressure), the low-resistance layer with a large amount of copper becomes a coarse structure, and the high-resistance layer with a small amount of copper becomes a dense structure, resulting in an uneven structure.

As a result, cracks tend to occur during firing, which has a negative effect on the life of the brush.5 The present invention was made based on the above circumstances, and its purpose is to prevent To provide a laminated brush whose lifespan is prevented from decreasing by preventing cracking over time.

[Means for Solving the Problems] In order to achieve the above object, the present invention comprises at least two layers, a low resistance part and a high resistance part, which have different resistances depending on the content of copper, and the low resistance part and the high resistance part have different resistances depending on the content of copper. In a laminated brush in which a high-resistance part and a high-resistance part are manufactured by integral molding, the low-resistance part is made of a low-resistance material mixed with copper powder that is easily plastically deformed and has excellent formability; The technical means is that it is made of a high-resistance material mixed with copper powder, which is difficult to deform and has poor formability.

[Operations and Effects of the Invention] The laminated brush of the present invention having the above structure has a low resistance material that forms the low resistance part mixed with copper powder that is easily plastically deformed and has excellent formability, and a high resistance part that forms the high resistance part. Copper powder, which is difficult to plastically deform and has poor formability, is mixed into the high-resistance material.

Therefore, when a low-resistance material with a large amount of copper and a high-resistance material with a small amount of copper are pressure-molded at the same time, the structure of the low-resistance part and the high-resistance part becomes Non-uniform differences are reduced and a more uniform structure can be achieved.

As a result, it is possible to prevent cracking during firing and to prevent a decrease in service life.

[Example] Next, the laminated brush of the present invention will be described based on an example shown in the drawings.

FIG. 1 is a side view of a laminated brush in sliding contact with a commutator.

The laminated brush 1 of this embodiment is made of copper (Cu), which is a low resistance material.
A low resistance part 2 and a high resistance part 3 with different resistances depending on the content of
It consists of two layers and is provided in sliding contact with the outer peripheral surface of the commutator 4 of the rotating electric machine. At this time, with respect to the rotation direction of the commutator 4 (indicated by the arrow in FIG. 1), the low resistance section 2 is arranged on the front side (on the left side in FIG. 1) and the high resistance section 3 is arranged on the rear side. .

Note that number 5 in FIG. 1 is a pigtail.

An example of a method for manufacturing the laminated brush 1 will be explained based on FIG. 2.

First, graphite and a binder (such as phenol) are mixed with alcohol (2-a).

Thereafter, the alcohol is dried, and the particle size of the treated graphite is adjusted by crushing and classification (2-b, 2-c).

Next, this treated graphite and 48% by weight electrolytic copper powder that is easy to mold.
, and 34% by weight of crushed copper powder, which is difficult to mold, are separately mixed to prepare a mixed powder 2 which becomes a low-resistance material and a mixed powder 3a which becomes a high-resistance material (2-d).

After filling the mold 6 with one of the mixed powders 2f, the lower punch 7 is lowered by a predetermined amount and the other mixed powder 3a is filled (2-e).

After that, the upper and lower punches 7.8 are used to pressurize and form the brush shape at a predetermined pressure, and then sinter it to form the low resistance part 2 and the high resistance part 3.
A molded product consisting of two layers is obtained.

This laminated brush 1 uses electrolytic copper powder, which is easy to form into a mixed powder 2f with a large amount of copper, and crushed copper powder, which is difficult to form into a mixed powder 3a, which has a small amount of copper. When molded, it is possible to form a relatively uniform structure with little difference in unevenness between the low resistance part 2 side and the high resistance part 3 side.

Therefore, cracks due to non-uniform structure can be prevented during firing, and a decrease in the life of the laminated brush 1 can be prevented.

In addition, the laminated brush 1 obtained by this integral molding can prevent peeling at the joint surface compared to a case where the low resistance part 2 and the high resistance part 3 are bonded together with an adhesive or the like.
The durability of the brush 1 can be increased.

In addition, although electrolytic copper powder and crushed copper powder are shown as copper powder that is easily plastically deformed and has excellent formability, and copper powder that is difficult to plastically deform and has poor formability, the present invention is not limited to these. .

Although the laminated brush 1 of this embodiment is shown as having two layers, the low resistance part 2 and the high resistance part 3, it may be three or more layers.For example, in the case of three layers, the low resistance part is Place it in the center and place high resistance parts on both sides.

[Brief explanation of the drawing]

FIG. 1 is a side view of a laminated brush in sliding contact with a commutator, and FIG. 2 is an explanatory view showing a method of manufacturing the laminated brush. 1 in the diagram...Laminated brush

Claims (1)

[Claims] 1) A laminate comprising at least two layers, a low resistance part and a high resistance part, each having a different resistance depending on the copper content, and the low resistance part and the high resistance part are manufactured by integral molding. In the brush, the low resistance part is made of a low resistance material mixed with copper powder that is easily plastically deformed and has excellent formability, and the high resistance part is made of a low resistance material mixed with copper powder that is difficult to plastically deform and has poor formability. A laminated brush characterized by being constructed of high-resistance materials.