JPH0676259B2 - Method for producing carbon material for sliding current collection - Google Patents

Description

The present invention relates to a method for producing a carbon-based sliding current collector material. More specifically, the present invention relates to a method for producing a carbon-based sliding current collecting material applicable to a pantograph sliding plate, a current collecting material for electric motors and the like.

[Conventional technology]

At present, there are roughly two types of sliding current collecting materials: metal materials such as casting alloys and sintered alloys, and carbon materials.

Metal-based sliding current collectors have extremely low electrical resistance and high strength, but they have more arc generation compared to carbon-based sliding current collectors, and have the disadvantage of increased wear due to their high strength. have.

Conventionally, a pantograph sliding plate material for current collection includes a metal-based sliding current collector such as a casting alloy such as copper, a copper-iron alloy or a copper-tin-zinc alloy, or a sintered alloy such as a copper alloy or an iron alloy. Although materials are mainly used, the use environment of pantograph sliding plates for current collection has become more severe in recent years due to an increase in current collection capacity such as cooling of vehicles and an increase in vehicle operating speed. Recently, the derailing rate has increased with the speeding up of vehicles, the amount of mechanical wear and the amount of arc wear have increased, and problems such as abnormal wear caused by freezing of trolley wires in cold regions,
There is also a problem such as noise pollution that the sliding noise is large. Therefore, in view of these abrasions, there is a demand for a current-collecting material having good sliding characteristics that reduces wear of not only the sliding plate itself but also other materials such as trolley wires and electromotive rails. In addition, the occurrence of an arc causes not only arc wear but also radio wave interference, and is therefore regarded as a problem.

Carbon-based materials are expected to be able to compensate for the drawbacks of these metal-based sliding materials. This carbon-based sliding current collector material has good self-lubricating properties and relatively low electrical resistance, has excellent arc resistance, is lightweight, and has the features of low sliding noise, It is possible to cover the drawbacks of the metal-based sliding current collector material.

However, this carbon-based material has the drawbacks of considerably higher electric resistance and extremely low strength as compared with a metal-based material, and therefore cannot be used in locations where a large force directly acts. Currently, these carbon-based materials are widely used for motor brushes and the like. By the way, even in the field where such a carbon-based sliding current collector material is used, the usage conditions thereof are becoming severer, and under the present circumstances, further improvement of its wear resistance and reduction of electric resistance are further required. . In addition, carbon-based materials are easily broken due to their brittleness when carbon alone is used, and if broken, the current collecting material is scattered, which is dangerous. It may stop.

At present, investigations are being made in various fields to solve the drawbacks of these carbon-based sliding current collector materials. For example, (1) impregnating a carbon-based sliding current collector with a metal (Japanese Patent Publication No. 52-822).
Or (2) by adding metal powder to the raw material powder of the carbon material (Japanese Patent Laid-Open No. 60-238,402),
A method of lowering electric resistance and improving strength has been proposed. Further, (3) a method of blending metal fibers with a carbon material raw material, molding and firing (JP-A-62-72564), and (4) blending metal fibers with a carbon material raw material and unidirectionally orienting And molding and firing (JP-A-62-19)
No. 7,352, JP-A No. 61-245,957) and the like have also been proposed.

[Problems to be Solved by the Invention]

However, although the above methods (1) and (2) can be expected to have some effect in improving strength, they have low efficiency of lowering electric resistance and cannot be expected to have an effect in preventing brittle fracture. The method 1) requires special equipment for impregnating the metal. Also, (3)
In the method (1), the use of the metal fiber has a high efficiency of reducing the electric resistance, but the metal fiber cannot be added in a large amount, and thus it is difficult to sufficiently reduce the electric resistance. Further, in the method of (4), since the fibers are arranged in one direction, cracks are likely to occur in a direction parallel to the orientation direction of the fibers and weaken in a specific direction.

Therefore, the present inventors have noticed that by dispersing the metal fiber in the carbon material, the electrical resistance is remarkably reduced, and further, the brittleness and chipping which are defects of the carbon material are improved, and further, At this time, it was found that a large amount of metal fibers can be added to the carbon material by using a raw coke which itself contains a binder component necessary for sintering carbon powder as a carbonaceous raw material. completed.

Therefore, an object of the present invention is to provide a high-strength carbon-based sliding material that has a lower electric resistance than conventional carbon-based materials and that has excellent bending strength and impact resistance and resistance to brittle fracture. It is to provide a method of manufacturing a current collecting material.

[Means for Solving the Problems]

The present invention is a self-sintering raw coke containing 8 to 14 wt% of volatile matter, which is prepared by the chattering cutting method, and exceeds 25 vol% and 60 vol of metal fibers having a fiber diameter of 1 mm or less and a fiber length of 10 mm or less.
%, And the mixture is added and mixed in a range of less than 10%, and then molded and fired.

In addition, the present invention is a carbonaceous raw material obtained by adding graphite powder to a self-sintering raw coke containing a volatile content of 8 to 14 wt%, which is prepared by a chattering cutting method and has a fiber diameter of 1 mm or less and a fiber length. This is a method for producing a carbon material for sliding current collection, in which metal fibers having a diameter of 10 mm or less are added in a range of more than 25 vol% and less than 60 vol%, mixed, and then molded and fired.

Hereinafter, the present invention will be described in more detail.

As the carbonaceous raw material used in the present invention, as described above,
A crushed raw coke containing the binder component is suitable, and a large amount of metal fibers can be added only by using this raw material.

As a method for producing such raw coke, for example, there is a method in which the pitch of petroleum-based, coal-based, etc. is heated under an inert gas stream at normal pressure to adjust the volatile content. Here, the volatile matter content is preferably 8 to 14 wt% in order to reduce the probability of cracking and swelling due to firing and increase the yield.

When it is desired to further improve the sliding characteristics, it is effective to use a carbonaceous raw material obtained by dispersing graphite powder in a carbonaceous matrix made of raw coke. The graphite powder used for this purpose may be either natural graphite powder or artificial graphite powder, and the particle size is 0.5 to 300 μm, preferably 10 to
It is 150 μm. Further, the addition amount is preferably 0.3 to 30 wt% with respect to the raw raw coke in order to cause the addition effect of graphite powder to appear and not to inhibit the sintering of the carbonaceous matrix.
%, More preferably 0.5 to 10 wt%. If you want to add a large amount of graphite powder, use raw coke with a large volatile content.

The metal fiber used in the present invention is a metal fiber prepared by the chattering cutting method having a polygonal cross section.
The use of the metal fibers prepared by the chattering cutting method brings about effects such as easy obtaining of a good molded product during compression molding. Note that the "battering cutting method" referred to here is, for example, Precision Machinery Vol. 47, No. 11, pp. 85-91 (1981).
In detail, under the heading "Production of Short Metal Fibers by Vibratory Vibration Cutting".

As the metal forming such metal fibers, copper, iron,
There is a copper-based alloy or a mixture thereof, and although not particularly limited, a metal having high strength and low electrical resistivity is desirable. However, if the material is extremely harder than the mating material that slides, the amount of wear of the mating material increases, and if the metal has a low melting point, the metal melts out during firing and the firing temperature cannot be set high, which is not preferable.

The shape of the metal fiber is not particularly limited, but the fiber diameter is 1 mm for reasons such as not inhibiting sintering with the carbonaceous matrix and making the blending uniform and easy.
Hereafter, the fiber length is preferably 10 mm or less.

Then, the amount of the metal fiber added is more than 25 vol% and less than 60 vol%, preferably more than 25 vol% to 45 vol% in terms of inner proportion. Limiting the amount of metal fibers added to this range is
This is because if the addition amount is 25 vol% or less, the electric resistance does not sufficiently decrease, and if it exceeds 60 vol%, the sintering of the carbonaceous raw material does not proceed sufficiently and the strength decreases.

Next, the method of mixing the carbonaceous raw material and the metal fiber may be a general method as long as it is a method capable of almost uniformly and randomly dispersing and mixing, such as a rocking mixer and a shaking method, and is not particularly limited. However, it is not preferable to use a mixing method in which a large shear force acts on the metal fibers during the mixing and the metal fibers are bent or cut.

The mixed raw material obtained by the above procedure is molded into a mold,
After molding by a method such as cold isostatic pressing (CIP) molding, it is fired at a temperature not higher than the melting point of the metal fiber in an atmosphere of an inert gas such as argon or nitrogen.

The sliding current-collecting material of the present invention does not mean that the contained metal fibers are oriented in a specific direction, and it is almost isotropic, particularly when produced by cold isostatic pressing, and is used in any direction. However, it is characterized by exhibiting characteristics such as high strength and low electrical resistivity.

Since the carbon material for sliding current collection according to the present invention has a good self-lubricating property of the carbon material as compared with the conventional sintered metal, the wear amount of the mating sliding material is reduced, and The sound is extremely low, and it is lightweight.
Further, the carbon material for sliding current collection according to the present invention can extremely reduce its electric resistance by using the metal fiber having a low electric resistance as compared with the conventional carbon-based sliding current collection material. In the cross-section portion, the metal fibers are finely and uniformly scattered in the matrix, and have advantages such as excellent arc resistance. In addition, by reinforcing it with metal fibers, it is resistant to brittle fracture, and even if it breaks, it is connected by the metal fiber parts so it does not scatter, and it is safe, high-strength, and impact-resistant metal fiber reinforced. A type carbon-based sliding current collector material is obtained.

The carbon material for sliding current collection according to the present invention can be widely applied as a current collecting material such as a current collecting brush for an electric motor, in addition to the use as a pantograph sliding plate.

〔Example〕

Hereinafter, the present invention will be specifically described based on Examples.

Example 1 A self-sintering raw coke having a volatile content of 12 wt% crushed to an average particle diameter of 8 μm was used to obtain a fiber diameter of 60 μ obtained by a chattering cutting method.
2,000kg / cm ² by adding 27vol% of iron fiber with m and fiber length of 3mm
After being molded into a size of 40 × 120 mm × 20 mm with a molding pressure of, it was baked at 1,000 ° C. in a nitrogen atmosphere to produce a sliding current collector material.

Example 2 A sliding current collector material was produced in the same manner as in Example 1 except that the amount of iron fiber added was 33 vol%.

Example 3 A sliding current collector material was produced in the same manner as in Example 1 except that the amount of iron fiber added was 40 vol%.

Example 4 The raw raw coke used in Example 1 had an average particle size of 100.
A sliding current collector material was produced in the same manner as in Example 1 except that carbonaceous raw material powder was prepared by adding 1 wt% of natural graphite of μm to this raw coke, and this carbonaceous raw material powder was used. did.

Example 5 A sliding current collector material was produced in the same manner as in Example 1 except that the iron fiber used in Example 1 was replaced with copper fiber obtained by the chattering cutting method.

Comparative Example 1 2,000 self-sintering raw coke crushed to an average particle size of 8 μm
After molding to a size of 40 × 120 mm × 20 mm with a molding pressure of 0 kg / cm ^2, the sliding current collector was manufactured by firing at 1,000 ° C. in a nitrogen atmosphere.

Comparative Example 2 Self-sintering raw coke crushed to an average particle size of 8 μm and copper powder having an average particle size of 30 μm were mixed at a ratio of 7: 3 (weight ratio), and molded and fired in the same manner as in Comparative Example 1. A sliding current collector material was obtained.

Comparative Example 3 15 wt% of polyvinyl chloride having an average particle size of 30 μm was used as a pore forming agent in a self-sintering raw coke crushed to an average particle size of 8 μm.
The mixture was added and pressure-molded at 1,500 kg / cm ² , and then fired at 1,100 ° C. in a nitrogen atmosphere. Continued under 0.1 Torr at 800 ℃
Immerse the above-mentioned fired body in the Cu-Sn alloy (50:50) melted in, and pressurize to 30 kg / cm ² with nitrogen gas to perform metal impregnation,
A sliding current collector material was produced.

The bulk density, electrical resistivity, bending strength, and Charpy impact value of the carbon materials for sliding current collection prepared in each of the above Examples and Comparative Examples were measured. The results are shown in Table 1.

As is clear from the results of Table 1, the sliding current collecting carbon material obtained by the method of the present invention not only has a lower electric resistance than the conventional carbon material, but also has a higher bending strength and impact resistance. It was found that the material exhibits excellent strength.

[Advantages of the Invention] According to the present invention, while maintaining the characteristics of the carbon-based sliding current collector material that is lightweight and has excellent performance in terms of lubricity, arc resistance, low noise, etc., at the same time, excellent low electrical It is possible to manufacture a very useful carbon material for sliding current collection, which has resistance and is also excellent in bending strength and impact resistance and resistant to brittle fracture.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichiro Fujimoto, 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Inside Nippon Steel Co., Ltd. Technical Research Institute (72) Koichiro Mukai 1618, Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Address: Nippon Steel & Co., Ltd. First Technology Research Institute (72) Inventor Kenichi Fujimoto 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Nippon Steel & Co., Ltd. First Technology Research Institute (72) Inventor Hiroshi Tsuchiya Tokyo 2-8-8 Hikari-cho, Kokubunji 38 Incorporated Railway Technical Research Institute (72) Inventor Nobuyoshi Ogata 62-6 Nakatsuyama, Kawauchi, Ogo-cho, Kurokawa-gun, Miyagi (56) Tohoku Kyowa Carbon Co., Ltd. (56) References 62-72564 (JP, A) JP 61-245957 (JP, A) JP 2-160663 (JP, A) JP 62-36075 (JP, A) JP 62-197352 (JP, A) JP Akira 61-247661 (JP, A) JP flat 2-69353 (JP, A)

Claims (2)

[Claims] 1. A self-sintering raw coke containing 8 to 14 wt% of volatile matter, which is prepared by a chattering cutting method and has a fiber diameter of 1 mm.
60v over 25vol% of metal fibers with a fiber length of 10mm or less
A method for producing a carbon material for sliding current collection, which comprises adding and mixing in a range of less than ol%, and then molding and firing. 2. A carbonaceous raw material obtained by adding graphite powder to a self-sintering raw coke containing 8 to 14 wt% of volatile matter, which is prepared by a chattering cutting method and has a fiber diameter of 1 mm or less and a fiber length of 1
A method for producing a carbon material for sliding current collection, comprising adding metal fibers having a diameter of 0 mm or less in a range of more than 25 vol% and less than 60 vol%, mixing, molding and firing.