JP2641695B2 - Manufacturing method of metallic graphite brush - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a metallic graphite brush, and more particularly, to a specific graphite binder for reducing the friction coefficient of metallic graphite which is a component of the brush and increasing the bonding strength. The present invention relates to a method for producing a metal-graphite brush using a specific amount.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 90-51345 discloses a method for manufacturing a metallic graphite brush, which is a typical prior art.
No. 6,086,045. This patent is a graphite material that prevents the surface film from being excessively formed on the commutator surface of rotating devices such as motors, reduces brush wear at high speed rotation with large capacity, and prolongs the service life. The present invention relates to a brush manufacturing method.

That is, in such a brush manufacturing method, powders of α-aluminum abrasive, molybdenum disulfide (MoS ₂ ) and tungsten disulfide (WS ₂ ) each having a diameter of 50 μm or less are mixed with a binder solution. And 7
Manufacture 0-300 μm particles, 70% by weight of artificial graphite powder
And a novolak-type phenol resin as a binder and methanol were added and kneaded, and then pulverized to a particle size of 100 μm.
A powder is prepared by mixing a graphite powder with a grinding agent + a lubricant + a binder in an amount of 0.5 to 15% by weight,
Molded at a pressure of 0.25 ton / cm ² ,
Firing.

On the other hand, in the conventional method of manufacturing a metallic graphite brush for rotating equipment, particularly for a small motor used in a small car, the amount of the metal component is changed in accordance with desired output characteristics and durability characteristics. For example, if a high output is desired, the metal is added in an amount of 60 to 90% by weight, and if a high durability is desired, the metal is added in an amount of 10 to 50% by weight. In addition, in order to improve lubricity,
Natural graphite was used as graphite.

Further, in order to improve the durability and high output of the brush and the noise reduction characteristics of the motor, the amount of the binder and the type of the resin as the binder, for example, novolak type phenol resin, resol type phenol resin, bisphenol By selecting resin A type and epoxy-resin, etc., the bond strength and porosity were adjusted.

[0006]

However, in such a conventional method of manufacturing a metallic graphite brush, in order to improve the output characteristics of the motor, the method of increasing the metal content is not suitable for reducing the metal content of the brush. When the value is increased, the resistivity of the brush is reduced, but the abrasion resistance of the brush and the motor noise reduction characteristics are adversely affected.

Further, when a binder is further added to improve the bonding strength after firing the brush, the bonding strength is improved as the amount of addition increases. However, this
In the case of (1), since the brush shrinks greatly and the porosity decreases, the friction coefficient of the brush increases, and a phenomenon that the motor noise caused by the brush increases appears. By the way, the type of binder
Separately have a specific different carbon content, the binder species
By changing the type, besides the porosity of the manufactured brush,
The amount of carbon derived from the binder due to this difference in carbon content, that is,
The amount of amorphous carbon (hard carbon) is affected. Binder
If the amount of amorphous carbon depends on the type and amount of
The electrical resistance of the brush increases even if the porosity decreases,
In addition, the motor noise becomes extremely large. This is commutator graphite
Acting as a polishing agent for removing the film consisting of oil and lubricating oil
Because a large amount of crystalline carbon removes the film excessively
There is . In addition, a binder made of a single resin must have sufficient binding strength.
When used in an amount that provides the desired porosity, the desired porosity can be obtained.
Even so, the range of variation in the amount of carbon derived from the binder is limited.
You. Therefore, the desired bond strength and porosity can be achieved.
With the conventional binder amount that can be controlled, the amount of amorphous carbon is controlled
Removes excess film to form an appropriate amount of graphite / lubricant film
And thus reduce the electrical resistance of the brush as a commutator
Smooth current supply and lubrication of the film
It was difficult to reduce noise.

Incidentally, as a method of solving such a problem of the prior art, conventionally, in order to reduce the coefficient of friction, the content of the metal is reduced, and in order to reduce the fluctuation of the contact voltage, a pure metal is used. A method of using graphite, molybdenum disulfide or the like as a lubricant to enhance heat and wear resistance, and a method of using one or two phenolic resin binders to increase bonding strength was also adopted. .

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a metallic graphite brush, in which a friction coefficient which is an important factor for noise reduction characteristics and a resistivity which is an important factor for output characteristics are reduced. It is an object of the present invention to provide a method for producing a metallic graphite brush.

Another object of the present invention is to reduce the noise of the motor by adjusting the carbon content of the binder, improving the bonding strength of the metallic graphite which is a constituent of the brush, and reducing the friction coefficient of the brush. An object of the present invention is to provide a method for manufacturing a metallic graphite brush capable of improving characteristics.

Still another object of the present invention is that the additives contained in the brush composition are each composed of 1.5% by weight of molybdenum disulfide and 1% by weight of lead. Novolak-type phenol resin and furfural resin are contained in a ratio of 50:50, and 7.5% by weight based on graphite powder.
It is an object of the present invention to provide a method for manufacturing a metallic graphite brush which can be added to thereby improve product strength.

[0012]

In order to achieve the above object, a method for manufacturing a metallic graphite brush according to the present invention includes the following steps. B) 55 to 70% by weight of natural graphite powder, 25 to 40% by weight of electrolytic copper powder, 1 to 5% by weight of molybdenum disulfide and lead as a lubricant, and a novolak type phenol resin and a furfural resin Producing a mixed resin powder as a binder in an amount of 1 to 15% by weight based on the natural graphite powder; b) wet-mixing the natural graphite powder and the mixed resin powder and optionally granulating the mixed powder. C) producing a powder having a particle size of 200 μm or less; and c) applying a composition obtained by mixing the material obtained in the above step b) with other raw materials at a pressure of 2-3 ton / cm ² . After pressing, baking at a temperature of 600 to 800 ° C., in which a lead wire is simultaneously attached. In the present invention, the copper powder particle distribution has an average of 27 μm,
The mixing ratio of the raw material powder is 62.5% by weight of natural graphite, 35% by weight of electrolytic copper powder, and 2.5% by weight of additives. The novolak phenol resin and the furfural resin are 50:50 weight ratio as a binder. It is preferable that the mixed resin mixed in the above is added at 7.5% by weight based on the natural graphite.

[0013] In particular, in the method for producing a metallic graphite brush of the present invention, as a binder, a mixed resin obtained by mixing a novolak type phenol resin and a furfural resin in a weight ratio of 50:50 is 1 to 1 with respect to natural graphite. Desirably, it is contained in an amount of 15% by weight.

[0014]

DETAILED DESCRIPTION OF THE INVENTION In the method for producing a metallic graphite brush of the present invention, for example, a metallic graphite brush can be produced by the following specific method.

A mixed resin as a binder obtained by mixing natural graphite particles with a novolak type phenol resin and a furfural resin in a weight ratio of 50:50 is used in an amount of 7.5% by weight based on the natural graphite. And wet-mixed, dried, and then pulverized to obtain a graphite / resin powder having an average particle size of 200 μm or less.

The graphite / resin powder and other raw materials, ie, an electrolytic copper powder having an average particle diameter of 27 μm, an electrolytic copper powder having an average particle diameter of 27 μm, and molybdenum disulfide and lead having an average particle diameter of 27 μm or less are mixed with graphite. : 62.5% by weight, copper powder: 35
% By weight, molybdenum disulfide: 1.5% by weight, and lead:
After mixing at a composition of 1.0% by weight and press-molding at a pressure of 2.75 ton / cm ² , a heat treatment is performed at a temperature of 700 ° C., and at the same time, a lead wire is attached, and then processed so that it can be mounted on a motor. Treated to obtain metallic graphite brush.

That is, the method for producing a metallic graphite brush of the present invention is as described below. First, 55-7
0% by weight, preferably 57.5 to 70% by weight of natural graphite powder, 25 to 40% by weight, preferably 27.5 to 40% by weight of electrolytic copper powder, and a total of 1 to 1 as additives for improving lubricating properties. 5% by weight, preferably a total of 2.5% by weight, of molybdenum disulfide and lead powder are provided.

The molybdenum disulfide and lead as additives may be used in any amount as long as the total amount is as described above.
For example, the powder of molybdenum disulfide is preferably 0.7
5 to 3% by weight, more preferably 1.5% by weight, the lead powder is preferably 0.25 to 2% by weight,
More preferably, it is used in an amount of 1.0% by weight.

Of these prepared powders, at least natural graphite powder and 1 to 15% by weight of a binder based on the natural graphite powder are wet-mixed, preferably dried, and then pulverized.
A powder having an average particle size of 0 μm or less is obtained.

When the graphite powder is natural graphite, it has better lubricating properties than artificial graphite, so that the sliding characteristics are improved. The particle size distribution of the graphite raw material powder is preferably from −150 μm to +6.
3 μm: 30 to 40% by weight, −63 μm to +45 μm:
25 to 35% by weight, -45m: 30 to 40% by weight, more preferably -150m to + 63m: 35% by weight, -63m to + 45m: 30% by weight, -45m
m: desirably 35% by weight.

As the binder, a mixed resin obtained by mixing a novolak type phenol resin and a furfural resin is used, and the mixing ratio of these resins is such that the total weight of the resin is 100%.
In this case, the ratio is preferably from 25:75 to 75:25, particularly preferably 50:50. By using a mixed resin having such a mixing ratio, the most excellent mixing effect between graphite and resin is obtained. be able to.

As described above, in the present invention, the mixed resin as a binder is added to the graphite in an amount of 1 to 15% by weight, preferably 7.5% by weight, wet-mixed, and then preferably dried. Then, pulverization is performed to obtain a graphite / resin powder having an average particle diameter of 200 μm or less.

In addition to the obtained graphite / resin powder, other raw materials such as metal powder, preferably 25 to 40 μm,
More preferably, electrolytic copper powder having an average particle size of 27 μm is used, and as an additive, preferably 10 to 30 μm.
A ground powder of molybdenum disulfide and lead having an average particle size of less than 27 μm, more preferably less than 27 μm, is used. These powders are, for example, natural graphite: 62.5% by weight,
Electrolytic copper powder: 35% by weight, molybdenum disulfide: 1.5% by weight, and lead: 1.0% by weight are mixed. Electrolytic copper powder is superior to other copper powders in electrical conductivity and sliding properties when mixed with graphite. Further, the metal powder may be added at the time of kneading graphite and resin.

If the amount of the binder is more than 15% by weight, the resistivity of the brush increases, and it becomes difficult to form a commutator film during operation of the motor.
Instead, the conductivity may be reduced.

These mixed powders are usually added in an amount of 2-3 ton /
After pressing under a pressure of ² cm ² , preferably 2.75 ton / cm ² , the temperature at which the binder is carbonized, usually 600 to 800
℃ (preferably 700 ° C.)
At the same time adhering to the lead wire, then it can instrumentation wear to the motor
To produce metallic graphite brushes
be able to. Novolac-type phenol tree as binder
Baking using a mixed resin of fat and furfural resin
If carbonized, only the novolak type phenol resin
Compared to the case of firing and carbonizing with a binder, the product
High shrinkage, thus reducing porosity,
The carbon content of the agent can be set to a desired value. This porosity
Reduction is not enough to significantly increase motor noise.
And contributes to reduction of electric resistance. Also, this binder
Amorphous carbon derived from the carbon in the coating on the surface of the commutator
It has an abrasive effect to prepare. In the method of the present invention,
As described above, the amount of carbon (amorphous carbon amount)
Value and achieve a uniform mixing of graphite and binder
Then, the amorphous carbon formed by carbonizing the binder by firing is
It can be distributed uniformly. Achieved by the present invention
Action of amorphous carbon with the amount and distribution
Then, an optimum carbon / lubricant film can be formed. Accordingly
Te, the metal-graphite brush manufacturing method of the present invention, the brush
To improve the motor output characteristics by reducing the electrical resistance of the motor.
Porosity due to the lubricating effect of the film.
Friction resistance and motor noise despite the reduction of noise
Can be reduced.

[0026]

The metal graphite brush 1 was manufactured according to the above-described specific method, and the metal graphite brush 1 was manufactured in the same manner as the above-described specific method except that only the novolak type phenol resin was used as the binder. The above effects of the present invention will be more specifically described with reference to a comparative example in which the quality brush 2 is manufactured.

Further, a magnification indicating a state where a raw material mixture of the same graphite / resin powder, electrolytic copper powder, molybdenum disulfide and lead as the raw material of the graphite brush 1 of the embodiment is kneaded and fired on a substrate. FIG. 2 shows a 10-times photograph, and FIG. 1 shows a 10-times photograph showing a state in which a raw material mixture similar to the raw material of the graphite brush 1 of the comparative example was kneaded and fired on a substrate.

As shown in FIG . 1, the metal graphite brush 2
Novolac-type phenol as a binder
At 700 ° C using a raw material mixture using only
If fired, the fired product of this mixture must be heterogeneous.
Was observed. This is because the resin component as a binder and other
Because of poor wettability with the components of
This is because the mixture could not be produced. Also,
As shown in FIG. 2, the raw material for manufacturing the metallic graphite brush 1
Yes, novolak type phenolic resin and
Including a mixed resin obtained by mixing 50:50 of furfural resin
When firing at 700 ° C. using the raw material mixture, the binder and
Good wettability between the mixed resin component and other components
Since a homogeneous mixture of raw materials for firing can be obtained,
It was also observed that the fired product of the compound was very homogeneous. This
The ability to produce homogeneous fired products such as
This is a particularly important advantage in mass-producing products.

When a binder having an excessively large amount of carbonization is used, the bonding force is increased, but the lubrication characteristics are adversely affected, the friction coefficient is increased, and the motor noise due to the brush is increased. .

In the present invention, a mixed resin obtained by mixing a novolak type phenol resin containing about 70% of carbon and a furfural resin containing about 60% of carbon is used as a binder. Was appropriately selected to control the amount of carbon in the binder .

Further, using each powder having the composition shown in the above specific method, a novolak type phenol resin and a furfural resin are mixed at a weight ratio of 50:50 to form a binder, and a metal produced using this binder is prepared. In the case of the graphite brush 1,
Uniformity of graphite and binder compared to metallic graphite brush 2
Achieving proper mixing and carbonizing the binder by firing
Amorphous carbon could be distributed uniformly. Accordingly
According to the present invention, while having a desired bonding strength,
Motor output with low electrical resistance due to desired porosity
Good properties, as well as the amount and distribution of amorphous carbon
Carbon / lubricant film removal and smelting realized by adjusting
To have a polishing function, that is, an optimal film-forming ability,
Metallic graphite bra with low coefficient and high motor noise reduction characteristics
It can be seen that the service can be provided.

Further, the metallic graphite brushes 1 and 2 produced by the above-mentioned method were mounted on a 160 W capacity automotive heater blower motor, and a load of 4.7 kg / cm was tested. Further, the heater blower motor for an automobile was placed in a soundproof room, the motor speed was set to 1500 rpm, and the frequency of the noise generated under no load was analyzed to evaluate the noise between the brush and the commutator.

Table 1 below shows the metallic graphite brush 1 of the example using a mixed resin obtained by mixing a novolak type phenol resin and a furfural resin at a ratio of 50:50 as a binder.
And the measurement results of density, porosity, resistivity, coefficient of friction, output and noise of the metal graphite brush 2 of the comparative example using only the novolak type phenol resin as the binder.

[0034]

[Table 1]

According to Table 1, a novolak type phenol resin and a furfural resin were used as binders in a weight ratio of 5%.
The metal graphite brush 1 of the example using the mixed resin mixed at 0:50 was compared with the metal graphite brush 2 of the comparative example using only the novolak type phenol resin as the binder.
It can be seen that since the density is high and the porosity is low, the resistivity is reduced and the output characteristics are improved, and the friction coefficient is low and the noise reduction characteristics are improved.

[0036]

As described above, according to the method for manufacturing a metallic graphite brush according to the present invention, the above specific amount of natural graphite powder, electrolytic copper powder, molybdenum disulfide and lead as additives are used. , Novolak type phenolic resin and furfural resin are mixed in a specific ratio as a binder and mixed with a mixed resin, and then molded and fired to produce a metallic graphite brush. Since the shrinkage is large and the porosity can be reduced, the resistivity of the brush is reduced, the output characteristics of the motor are improved, and the binder existing uniformly before firing is carbonized into amorphous carbon. As a result, the bonding force between graphite and graphite is improved, and the effect of adjusting the coating on the surface of the commutator can be exhibited.

[Brief description of the drawings]

FIG. 1 is a photograph at 10 × magnification showing a state in which a raw material mixture of a graphite brush 1 of a comparative example is kneaded on a substrate and fired.

FIG. 2 shows a state in which a raw material mixture of graphite / resin powder, electrolytic copper powder, molybdenum disulfide and lead similar to the raw material of the graphite brush 1 of the embodiment of the present invention is kneaded on a substrate and fired. It is a photograph at a magnification of 10 times shown.

Continuation of the front page (72) Inventor Li Jia-Sung South Korea, Kung Kido, Angsang, Walpie Dung, Hyundai 2 NDP 204-705

Claims (4)

(57) [Claims] 1. A method for producing a metallic graphite brush, comprising: a ) 55 to 70% by weight of natural graphite powder, 25 to 40% by weight of electrolytic copper powder, and 1 to 5% by weight of disulfide as an additive. It contains molybdenum and lead, a novolak type phenol resin and a furfural resin.
(B) wet mixing the natural graphite powder and the mixed resin powder, and optionally granulating to produce a powder having a particle size of 200 μm or less. And c) press-molding the composition obtained by mixing the material obtained in the above step b) with other raw materials at a pressure of ² to 3 ton / cm ² , followed by a temperature of 600 to 800 ° C. And baking at the same time so that lead wires are simultaneously attached. 2. In the step b), the natural graphite 5
5 to 70% by weight, the electrolytic copper powder 25 to 40% by weight,
The natural graphite powder is wet-mixed with 1 to 15% by weight of the binder, and the binder is a 25:75 to 75:25 novolak-type phenol resin and a furfural resin.
The method for producing a metallic graphite brush according to claim 1, wherein the mixture is mixed at a weight ratio of: 3. The natural graphite powder has a particle size distribution of -15.
0 μm to +63 μm: 30 to 40% by weight, −63 μm to
+45 μm: 25 to 35% by weight, −45 μm: 30 to 4
The method for producing a metallic graphite brush according to claim 1, wherein the weight is 0% by weight and the average particle size is 27 µm. 4. The natural graphite, electrolytic copper powder and lubricant are used in amounts of 62.5% by weight, 35% by weight and 2.5% by weight, respectively, and the binder is a novolak-type phenolic resin and furfural. 2. The method according to claim 1, wherein the resin is mixed in a weight ratio of 50:50, and is added in an amount of 7.5% by weight based on the natural graphite powder. .