FI83599B - Process for production of multi-hole metal profiles - Google Patents

Abstract

The invention relates to a process for the production of thick-walled, multi-hole metal profiles so that simple part-profiles 1, 3, 4 are joined together by electron beam welding and the multi-hole body which is thus obtained is further worked by drawing and heat treatment. <IMAGE>

Description

1 83599

METHOD OF MANUFACTURING MULTI - HOLE METAL PROFILES

This invention relates to a method of making thick-walled multi-hole metal profiles.

Typical applications for the product according to the invention are e.g. generators and large magnetic systems using perforated profiles as conductors. The material is pure or alloyed copper. The holes in the profiles act as coolant channels. High demands are placed on the dimensional accuracy, electrical conductivity and mechanical properties of conductor profiles ...

Extrusion is most often used in the production of perforated profiles. To make the holes, either long straight mandrels or the so-called Bridge tool. However, when making multi-hole profiles, the use of these methods involves many difficulties and weaknesses in the quality to be achieved. Long mandrels bend in extrusion, causing inaccuracy in the position of the holes. When using a bridge tool, a joint is formed in the base between the holes in the product, which poses a risk of leakage, especially because oxides and other contaminants often enter the joint.

Perforated profiles can also be made in accordance with GB 1 504 668 by drilling holes in the closed profile, after which the profile is further modified by drawing. However, the machinability of copper is very poor, which makes production by this method slow. When the ratio of the length of the hole to the diameter is very large, there are problems with the susceptibility of the drill to damage and deviation from the direction.

It is known to produce small copper profiles by TIG welding, e.g. Metals Handbook 8th edition, vol. 6, p. 342. However, the method is not suitable for large conductor profiles with a thickness of several tens of millimeters and where the material must be of uniform quality also in terms of mechanical properties.

2,83599

Electron beam welding is used in the process of U.S. Patent 3,566,071 for the manufacture of thin-walled heat exchangers. The method leaves an unmodified seam at the channel, which cannot be allowed in the conductor profiles.

The object of the present invention is to provide conductor profiles with precise dimensions, in which the mechanical and electrical conductivity properties are homogeneous over the entire cross-section. The essential features of the invention appear from claim 1.

The invention is illustrated by the accompanying drawings 1-3, which have cross-sections of conductor profiles according to the invention.

In Fig. 1, the conductor profile is made of several single-hole sub-profiles 1, which are connected to each other by longitudinal electron beam welding so that the seams 2 come outside the cooling holes, i.e. in the massive part of the profile. Known methods such as hot extrusion and, if necessary, drawing are used in the production of partial profiles. According to Fig. 2, two-hole partial profiles 3 or non-perforated partial profiles 4 according to Fig. 3 can also be used as partial profiles.

For subsequent machining of the weld dome and the root, protrusions 5 according to Fig. 3 can be made in the sub-profiles.

I-groove is used in electron beam welding, so the surfaces to be joined are made straight. After welding and machining, the profiles are shaped by pulling so that the holes have mandrels. This accurately achieves the final dimensions of the part. Finally, a heat treatment is performed in which, as a result of the recrystallization, the grain size and mechanical properties in the weld seam and elsewhere become similar. If the final product is to be stronger than annealed, 3,83599 annealing is performed before the last drawing. The method can be used to produce both symmetrical and asymmetrical profiles. The manufacturing method is available over a wide measuring range.

Making joints thick enough at high speed requires electron beam welding, which has a clearly higher penetration than other welding methods. When using a power of 75 kW, an penetration of approx. 150 mm is achieved. This method of welding is well suited, for example, to oxygen-free copper, which is welded to obtain non-porous seams. Oxygen-free copper refers to, for example, the copper grades sold under the trade names HCOKOF and OFHC. The transition and heat zones are very narrow and therefore the welding stresses and deformations remain small, so it is possible to join several long pieces together.

Example 1

Manufactured by hot extrusion and drawing single-hole sub-profiles with later projectable protrusions. These sub-profiles are welded together by electron beam welding to obtain the 2-hole profile shown in Figure 3. The extra protrusions are removed by machining, at the same time removing the defects that often occur at the base of the weld. The metal structure is now cold formed except for a narrow area on either side of the weld seam that is recrystallized.

The profile is pulled through the traction ring one or more times. the reduction in cross-sectional area is typically about 50%, but should be at least about 30% in order to achieve a uniform recrystallized structure in subsequent heat treatment. Traction usually requires the use of a mandrel inside the holes to control the tolerances and surface quality of the holes.

4,83599

The profile is heat treated, the typical temperature is approx. 550 ° C and the time is 30 min. The structure is now recrystallized throughout so that at the weld seam the structure does not differ from the rest of the structure.

If necessary due to dimensions or mechanical properties, the profile can still be further drawn and possibly heat treated again.

Claims (4)

A method for producing thick-walled, multi-hole metal profiles from oxygen-free copper, characterized in that at least two sub-profiles with one or more holes (1,3,4) are first produced, which are connected directly or via a snack by electron beam welding so that the electronic the jet welds (2) are placed outside the hole of the partial profile and the metal profile thus formed, after any welding of the weld, is post-treated by drawing to final dimensions and heat-treated to smooth the entire cross-section to homogeneity. Method according to Claim 1, characterized in that the sub-profile (1,3,4) is produced by extrusion in a manner known per se. Method according to Claim 1, characterized in that the sub-profile (1,3,4,) is known to be drawn per se. Method according to one of the preceding claims, characterized in that the partial profiles are connected to one another by electron beam welding in their longitudinal direction. 6 83599