JP2590207B2 - Manufacturing method of multi-core composite material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a multi-core composite material such as a superconducting wire.

[Prior art] Conventionally, after inserting only one metal strand into a metal pipe,
There is a technology for wire drawing and further compounding. In such a single-core composite, the inner surface of the pipe and the surface of the strand are roughened in order to improve the adhesion between the metal pipe and the metal strand, which are constituent materials of the composite material. But,
In a multi-core composite in which a large number of metal wires are inserted into a metal pipe, if the inner surface of the pipe and the surface of the wire are roughened, the wire may be broken during the surface reduction processing.

At the stage where many strands are inserted into the pipe, the filling rate inside the pipe is low, so the inner surface of the pipe and the strands, and the strands and strands are not in contact with each other on the whole surface, but are in local contact doing. If surface reduction processing (mainly wire drawing processing) is performed in this state, since the elongation of the metal pipe is generally larger than that of the inner wire, when the pipe elongates, the wires are dragged together to try to elongate. If the surface roughness of these components is large, the friction of the contacting parts is large,
A large force is locally applied to the portion, and a wire break occurs.

FIG. 1 is a partial cross-sectional view of a composite material that has been surface-reduced by a die. The component material when the composite material 10 is subjected to the surface reduction by passing through the die 20, that is, the pipe 11
And the strand 12 are shown. When the inner surface of the pipe and the surface of the wire are roughened, an excessive force acts on the wire 12 that is in contact with the inner surface of the pipe by extending the pipe 11 backward (in the direction of the arrow in the drawing) during surface reduction processing. Cracks occur in the wire, leading to disconnection.

[Problems to be Solved by the Invention] An object of the present invention is to provide a method for producing a multifilamentary composite material which does not cause wire breakage and gives a good multifilamentary composite material.

[Means for Solving the Problems] The gist of the present invention is to provide a method of manufacturing a multi-core composite material by reducing a surface area after bundling a plurality of metal strands in a metal pipe, The roughness of the inner surface of the metal pipe and the surface of the metal wire is 20μm or less, and the first pass surface reduction is wire drawing using a die having an approach angle of 12 ° or less. In the method for producing a multi-core composite material.

The roughness of the inner surface of the pipe and the roughness of the wire surface are each set to 20 μm or less. As a result, the friction between the inner surface of the pipe and the wire in contact with the inner surface of the pipe when the pipe extends rearward is reduced. If the surface roughness exceeds 20 μm, friction increases, slippage between the inner surface of the pipe and the wire becomes poor, and an excessive force acts on the wire. In the present specification, “surface roughness” is a ten-point average roughness Rz.

In the first pass area reduction processing to increase the filling rate,
Use a dice with an approach (full-width) of 12 ゜ or less. By moving the direction of deformation of the pipe toward the center of the pipe cross section as much as possible, the rearward extension of the pipe is suppressed as much as possible. If the die angle exceeds 12 °, the rearward extension of the pipe becomes too large, and the amount of deformation between the inner surface of the pipe and the wire is greatly different.

 The present invention is particularly useful in manufacturing superconducting materials.

Metal pipes are usually made of Cu or Cu alloy, for example, Cu-N
i, Cu-Sn, Cu-Be, etc.

Metal strands are usually NbTi, Nb, Sn, Cu, Cu / NbTi, Cu /
It is made of Nb and other composite materials coated with Cu alloy.

In the wire drawing in the first pass, the area reduction rate is preferably 40% or less.

[Effects of the Invention] In the present invention, it is possible to reduce the backward extension of the pipe, reduce the friction between the pipe inner surface and the strand, and prevent an excessive force from acting on the strand. Therefore, breakage of the strand is unlikely to occur, and a good multi-core composite material can be manufactured.

EXAMPLES Examples and comparative examples of the present invention will be described below.

Examples and Comparative Examples The inner surfaces of Cu pipes having an outer diameter of 20 mm and an inner diameter of 14 mm were polished with a nylon brush to produce Cu pipes having various inner surface roughnesses.

61 pieces of 1.5 mm diameter Cu / NbTi superconducting wires were bundled and put into this pipe to form a composite. At that time, the surface of the superconducting wire was polished with a nylon brush, and superconducting wires having various surface roughnesses were used.

These composites are combined with a dice approach angle of 6 °, 12 °
Wire drawing was performed with four types of dies of ゜, 15 ゜ and 18 ゜ with a reduction in area of 30%. Thereafter, the outer Cu pipe was removed and the condition of the wires inside was observed. The results are shown in the following table.

In the table, ○ indicates that the wire had no crack, Δ indicates that the wire had a small crack, and x indicates that the wire had a large crack.

When the die approach angle is 6 ° or 12 ° and the pipe inner surface roughness and strand surface roughness are 20 μm or less,
It can be seen that the strand was drawn well.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a composite material whose surface has been reduced by a die. 10 ... composite material, 11 ... pipe, 12 ... strand, 20 ... dice.

Claims (1)

(57) [Claims] 1. A method of manufacturing a multi-core composite material by bundling a plurality of metal wires into a metal pipe and then reducing the surface area thereof, wherein the inner surface of the metal pipe and the surface of the metal wire are provided. A method of producing a multi-core composite material, characterized in that the surface reduction of the first pass is wire drawing using a die having an approach angle of 12 ° or less.