JPH01152230A - Alloy for commutator of motor - Google Patents

Abstract

PURPOSE:To obtain the subject alloy having excellent wear resistance by adding specific ratios and specific contents of Mn and Si to Ag. CONSTITUTION:Ag alloy to which Mn and Si are incorporated in such a manner that the atomic ratio of Mn to Si is regulated to 5:3 and the total amount is regulated to 3-10wt.% or to which one or more kinds among Zr, Mg, La and Al are furthermore added in such a manner that the total amount is regulated to 0.5-2.0wt.% is used as the alloy having low contact resistance and excellent electric conductivity, workability and wear resistance as the material for a commutator of a motor having excellent electric characteristics and longer service life can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an alloy for a commutator of a motor that has particularly excellent wear resistance.

[Conventional technology]

The commutator comes into contact with the brushes when the motor rotates, and rotates while collecting current. There is a problem that discharge occurs due to the current flowing through the battery, causing damage.

■ It is said that the commutator slits get clogged with wear debris.

A so-called eye-catching phenomenon occurs, causing excessive current to flow through the motor windings and burning out the motor circuit.

■ Contact resistance increases due to wear products and oxides generated due to temperature rise at the contact area, making motor rotation unstable.

This was often accompanied by other inconveniences.

For this reason, as a material for motor commutators,
In addition to being required to have good conductivity and workability and low contact resistance, there has been a strong demand for excellent wear resistance.

Conventionally, Ag has been widely used as a material for motor commutators due to its low and stable contact resistance, but Ag has low hardness and is therefore fully satisfactory in terms of wear resistance. It wasn't.

Therefore, in order to improve the wear resistance of this Ag.

Up to now, Cu, Ni, In, Cd, etc. have been added in amounts of about 20 or less (usually several inches) each.

[Problem that the invention seeks to solve]

However, in recent years, as motors have become smaller and require higher rotational speeds, such as those used in VTRs, even these alloys are no longer sufficient in terms of wear resistance. I couldn't get any good results.

[Means for solving problems]

Therefore, the present inventors have taken the above-mentioned viewpoints into account.

This is the result of research aimed at finding a material for motor commutators that has good conductivity and workability, low contact resistance, and extremely high wear resistance.

■ The reason why conventional commutator materials had problems with wear resistance was that improvements in the wear resistance of conventional commutator alloys were also achieved by increasing the hardness of the entire matrix through solid solution strengthening. Yes, in this case.

The more alloying elements are added, the more the conductivity decreases, and the properties of the base metal, Ag, such as excellent oxidation resistance and low contact resistance, are lost, so the amount of alloying elements added is limited, and therefore it is difficult to improve wear resistance. There was a limit.

■ Therefore, if the hardness is increased using the dispersion strengthening mechanism caused by crystallization and precipitation, the wear resistance will be improved without impairing the excellent properties of Ag. Because substances (hereinafter referred to as crystallized substances, etc.) appear and these crystallized substances come into contact with the brush, the average hardness of the alloy and the expected wear resistance are even better. It will be done.

As a result of conducting various studies based on this recognition, we have come to the conclusion that this is the case.

Ag, Mn and 81 in an atomic ratio of 5=3, and.

Mn+Si: When added in an amount of 3 to 10% (qb is weight %, hereinafter, q in terms of composition indicates weight i%), an intermetallic compound of Mn and Si crystallizes or precipitates in the Ag matrix. Improves the wear resistance of the alloy.

Furthermore, if necessary, one or more of Zr, Mg, La, and M may be contained in a total of 0.5 to 2 or more, thereby increasing the amount of Ag itself by solid dissolving the excess components in Ag. It has been found that there is little decrease in conductivity, and furthermore, there is less wear and tear caused by arcs that occur when electrical circuits are opened and closed (arc resistance is improved).

This invention was made based on the above findings, and includes: (1) The atomic ratio of Mn and Si is 5=3, and Mn+8i: 3 to 10% is contained.

Ag and unavoidable impurities: motor commutator alloy consisting of the remainder, and (2) Mn
The atomic ratio of Si and Mn is 5:3, and Mn+Si:
Contains 3-10% and further.

One or two of Zr, Mg, La, AX
A total of 0.5 to 2 pieces of seeds or more.

Contains.

Ag and unavoidable impurities: remainder.

An alloy for motor commutators consisting of:

It has the following characteristics.

Next, the reason why the content of each component composition in the commutator alloy of the present invention is limited as described above will be explained.

(a) Mn and Sl By containing these components in an atomic ratio of 5:3, they precipitate or crystallize as Mn s Si s.1 The hardness and wear resistance of the alloy are improved. However, if the total content is less than 3 T,
The above effects were not sufficiently effective.

On the other hand, if the content exceeds 10, the amount of precipitation or crystallization becomes too large, which not only deteriorates the workability of the material but also deteriorates the contact resistance performance with the brush material. The content was determined to be 3 to 1096.

(b) Zr, Mg, La, A! Each of these components has the effect of reducing the wear and tear caused by the arc that occurs when an electric circuit is opened and closed, so they are added as necessary.

If the content is less than 0.5%, sufficient effects cannot be obtained for the above action, while if the content exceeds 2%, the workability of the alloy will decrease and the contact resistance will increase, so the content should be reduced to 0. It was set at .5 to 2%.

〔Example〕

Next, the present invention will be specifically explained based on examples.

First, Alloys 1-12 of the present invention and Comparative Alloys 13-20 having the compositions shown in Table 1 were manufactured by a conventional method. In Table 1, the * mark indicates a value outside the conditions of this invention.

Then, for each of these alloys, the electrical conductivity, wear resistance,
and contact resistance characteristics were measured, and the results are also shown in the $1 table.

The wear resistance was tested using a testing device similar to an actual motor. That is, as shown in FIG.
Each commutator alloy 1 to 20 shown in the table was used, and 50
Rotating at 0 Orpm, brushes with a thickness of 20.5 m and a width of 3 IEx as shown in numbers 2 and 3 were pressed with a force of about 30.9, and a current of 250 mA at 20 V was applied to this brush. After automatically adjusting the flow and rotating continuously for 500 hours at room temperature and humidity, the outer diameter of the brush sliding portion of member 1 was measured, and the abrasion resistance was evaluated based on the decrease in diameter 'NK. in this case.

For brushes 2 and 3, 62.5% Au - 30% Ag -
A 7.5% Cu alloy was used, which was spot welded to a pure CU terminal.

Furthermore, the contact resistance characteristics were evaluated by measuring the electrical resistance between both brushes before and after the above-mentioned test, and by the amount of increase in contact resistance obtained as the difference between the two.

〔Effect of the invention〕

It can also be seen from the results shown in Table 1 that alloys 1 to 12 of the present invention have much better contact resistance characteristics than comparative alloys 13 to 20.

As described above, according to the present invention, it is possible to obtain an alloy that has excellent wear resistance and exhibits high conductivity and low contact resistance necessary for a commutator, and this can be used as a commutator for a motor. By doing so, industrially useful effects such as excellent electrical properties and a long service life can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the abrasion resistance testing apparatus. In the drawing. 1... Slit processing member. 2.3...Brush, 4...Slit.

Claims (2)

[Claims] (1) The atomic ratio of Mn and Si is 5:3, and Mn
An alloy for a commutator of a motor, characterized in that it contains +Si: 3 to 10%, and the remainder (or more by weight) of Ag and unavoidable impurities. (2) The atomic ratio of Mn and Si is 5:3, and Mn
+Si: 3 to 10%, and further contains one or more of Zr, Mg, La, and Al in a total of 0.5 to 2%, Ag and unavoidable impurities: the remainder (by weight An alloy for a motor commutator characterized by comprising %.