JPH0426567A - Method for joining carbon sliding plate to aluminum-based material - Google Patents

Abstract

PURPOSE:To make a fitting jig light in weight and to reduce cost by coating a carbon sliding plate for a pantograph for a railway with copper and joining the copper coated surface to an Al-based material by a joining means at a low temp. CONSTITUTION:A carbon sliding plate 1 with a cupper coating layer 1-1 formed oh the entire surface by copper plating is joined to a current collector boat 2 made of an Al-based material with a brazing layer 3 in-between. Since the copper coating layer 1-1 improves the wettability of a carbon-metal composite material, the carbon sliding plate 1 can be joined to the Al-based material 2 by a joining means at a low temp. of <=450 deg.C such as brazing. The plate 1 is not affected by heat, cracking can be prevented and high bonding strength is obtd., accordingly the plate 1 can directly be fitted to the boat 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a means for attaching a sliding plate for a railway pantograph, and more particularly to a method for joining a carbon sliding plate to an aluminum-based material.

Conventional Technology As is well known, railway pantographs have a structure in which a sliding plate is attached to a collector boat that is attached to a diamond-shaped frame by a restoring spring. Conventionally, the sliding plate is made of cast alloy or sintered alloy. Metal-based materials have been used, but recently carbon-based materials, which can reduce wear and tear on mating materials such as trolley wires and electromotive rails, have begun to be used.

Materials for carbon sliding plates include compacts made only of carbon and graphite, and carbon/metal composites that take advantage of the excellent sliding properties of carbon and the electrical conductivity of metal. , it is difficult to join with metal by brazing, and its low strength makes it difficult to perform thread cutting directly on the molded body.

A conventional method for attaching a carbon slide plate is, for example, as shown in FIG.
There is a method in which a holding metal fitting (sheath) (23) formed with 4) is interposed between the sliding plate and a current collector boat (25) made of an aluminum material, and is attached with a bolt (26).

That is, in the case of a carbon sliding plate, it is difficult to directly fix it with bolts like a metal sliding plate because of its insufficient strength, so it is attached via a holding fitting (23).

On the other hand, Japanese Patent Application Laid-Open No. 62-204936 discloses that copper or steel alloy is bonded to graphite by high-temperature bonding means such as diffusion bonding or hard brazing (450°C or higher), and that a thick metal plate is bonded at a temperature lower than the above bonding temperature. Composites of graphite and metal bonded or bonded at temperature are disclosed.

Problems to be Solved by the Invention However, with the above-mentioned method of attaching the carbon sliding plate shown in FIG. , the sliding plate itself needs to be thicker, the protrusion (22) needs to be made of carbon, and the presser fitting (23) is required, which increases the weight and cost of the pantograph. It has the disadvantage of inviting

In addition, in the case of a composite material made of graphite and metal disclosed in JP-A No. 62-204936, when graphite and copper are bonded at high temperature, since there is a large difference in coefficient of thermal expansion between graphite and copper, During the process of returning to room temperature after joining, an extremely large stress is generated in the graphite, and cracks easily occur in the graphite, which has no plastic deformability and has low fracture stress, especially for large items such as pantograph sliding plates. There are many problems with getting stuck,
Hard brazing is difficult to apply.

This invention aims to reduce the weight and cost of pantographs by proposing a method of joining a carbon slide plate to an aluminum-based collector boat using a joining method such as brazing. be.

Means for Solving the Problems In order to improve the wettability of carbon/graphitic materials or carbon/metal composite materials, the present invention applies a copper coating to the surface of the material and uses low-temperature bonding methods such as soft brazing. This makes it possible to bond with aluminum-based materials.

When a carbon/graphite material is plated with copper, the carbon and steel are not alloyed, but are physically bonded to each other by penetrating the minute holes and irregularities on the surface of the carbon material.

Also, when copper and aluminum are joined using a brazing metal, a metallurgical reaction occurs at the interface between the two metals and the brazing metal, and a very small amount of the layers melt into each other, or diffuse, creating an alloy layer. .

This invention was discovered based on the above findings, and includes a method of applying copper coating to a carbon sliding plate and joining this copper coated surface to an aluminum material by low temperature bonding means, and a method of joining the bottom of the carbon sliding plate. A recess is provided, a sliding plate with this engaging recess is coated with copper, a connecting member made of an aluminum material having a shape that fits into the engaging recess is joined by low-temperature bonding means, and a bolt is attached to the connecting member. The gist of this paper is a method of fixing it to aluminum-based materials.

Function Carbon sliding plates are molded bodies made of only carbon/graphite materials, or molded bodies made of composite materials in which carbon/graphite materials are mixed with metal powder, ceramic powder, or fibers such as metal, carbon, and ceramics. can be made.

Aluminum-based materials include aluminum, aluminum alloys (eg, duralumin), and the like.

Chemical plating or electroplating is generally used to coat carbon sliding plates with copper, but thermal spraying, CV
A coating such as D may also be used.

The thickness of the copper coating layer is not particularly limited, but from the viewpoint of bonding strength, it is preferably 30 μm or more, while the upper limit is preferably about 50 μm from the economic point of view. Note that when the thickness is about 5 μm, the strength is low, and breakage occurs at the interface between carbon and copper or at the brazing filler metal layer.

As the low temperature joining means, soft brazing using a brazing material having a melting temperature of 450° C. or lower, blaze welding generally called low temperature welding or eutectic welding, etc. can be used.

The blaze welding method uses a special welding rod and flux to create a eutectic alloy in the welded area and joins, and is characterized by having little thermal effect on the base metal.

As the brazing filler metal, any brazing filler metal that is generally used for joining copper and aluminum-based materials may be used, but a Zn-Ag-Cd-based brazing filler metal is preferable because it provides high bonding strength.

In the method of forming a recess in a carbon sliding plate and low-temperature bonding a bolted member to the recess to fasten it to an aluminum material, the bolted member that fits into the recess is made of aluminum. This is to reduce the weight loaded on the collector boat made of materials.

Embodiment FIGS. 1 and 2 show an embodiment of the present invention. FIG. 1 illustrates a joining method corresponding to claim 1 of the present invention, and FIG. This is an example of a corresponding joining method.

In other words, Fig. 1 shows a carbon sliding plate (1) whose entire surface is copper-plated to form a copper coating layer (1-1), and a carbon sliding plate (1) with a copper coating layer (1-1) formed on the entire surface. This is an example where it is connected to Densetsu (2).

Further, in FIG. 2, an engaging recess (ii-i) is formed at the bottom.

After copper plating is applied to the carbon sliding plate (11) to form a copper coating layer (H-2), an aluminum bolted connecting member (12) is brazed to the engagement recess (11-1). The bolts (12) of the connecting member are connected through the layer (13) and inserted into the bolt holes (2-1) pre-drilled in the collector boat (2).
-1) and fastens the nut (14) to the bolt to fix it to the collector boat.

Note that it goes without saying that the copper coating layer only needs to cover the surface to be bonded to the aluminum-based material.

Further, in addition to the fixing method shown in FIG. 2, more reliable fixing can be achieved by combining the method of directly brazing the copper-coated carbon sliding plate and the current collector boat.

Next, the results of examining the bonding strength between a carbon sliding plate and an aluminum-based material using the method of this invention will be explained.

First, a carbon/graphite molded body is electroplated in a birophosphate steel solution to form a copper coating layer with a thickness of 5 μm and 30 μm on the surface, and then the temperature is raised to 350°C and a liquid is applied on the copper coating layer. A Zn-Ag-Cd brazing filler metal (FA-5, manufactured by Nippon Alumitsu Co., Ltd.) was filled using acidic flux (manufactured by Nippon Alumitsu Co., Ltd.: SDG Flux), and the flux was washed with water.

Thereafter, the above-mentioned brazing filler metal was rubbed onto the aluminum material heated to 350°C, and both brazing filler metal parts were joined together by pressing at a pressure of 6 kg/mm'' at a temperature of 350°C.

Note that heating to 350°C was performed using an oxygen/acetylene gas burner.

After that, 20mmφX 90110 with the joint part in the center
A 1-length tensile test piece was prepared and subjected to a tensile test, and the results of examining the tensile strength and fracture position are shown in Table 1.

As is clear from Table 1, when the copper plating thickness is 5 μm,
200kg/cm", which is sufficient strength, but the fracture location is partially at the carbon-copper interface or the brazing material layer, whereas with copper plating thickness of 30μm, the bond strength is 400kg/cm"
High strength was obtained, and since the fracture location was in the carbon base material, very good bonding was achieved.

As explained in detail in Table 1 below, according to the method of this invention, the carbon sliding plate and the aluminum material can be bonded at a low temperature of 450°C or less, so there is no thermal effect on the carbon sliding plate and there is no cracking. In addition to preventing such problems, the carbon sliding plate can be directly attached to the current collector boat because of its high bonding strength, which has the excellent effect of reducing the weight of the mounting jig and reducing costs. It is.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are diagrams showing one embodiment of the present invention.
The figure is a longitudinal sectional view showing an example of a joining method corresponding to claim I of the present invention, FIG. 2 is a longitudinal sectional view showing an example of a joining method corresponding to claim 2, and FIG. FIG. 3 is a vertical cross-sectional view showing an example of a method for attaching a sliding plate. 1.11... Carbon sliding plate 11-1... Engaging recess 1-1.11-2... Copper coating layer 2... Current collector boat 3.13... Brazing layer 12 ...Connection member with bolts Applicant: Sumitomo Metal Industries, Ltd.

Claims (1)

[Scope of Claims] 1. In a method for joining a carbon sliding plate made of a carbon/graphite material or a carbon/metal composite material to an aluminum material, after applying a copper coating to the carbon sliding plate, the copper coating is applied. A method for joining a carbon sliding plate and an aluminum material, the method comprising joining the surface and the aluminum material by low-temperature joining means. 2. In a method of joining a carbon sliding plate made of a carbon/graphite material or a carbon/metal composite material to an aluminum material, an engaging recess is provided at the bottom of the carbon sliding plate, and the carbon sliding plate with the engaging recess is provided. After coating with copper, a joining member made of an aluminum material having a shape that fits into the recess is joined by low-temperature bonding means, and fixed to the aluminum material with a bolt attached to the joining member made of an aluminum material. A method of joining a carbon slide plate and an aluminum material, characterized by the following.