| 摘要 |
PURPOSE:To improve the yield of noble metal by forming pipe ends of copper alloy, etc. at both ends of a central pipe part of noble metal to obtain a jacket pipe and forming projected parts at both ends of a core body to bring the core body into tight contact with the jacket pipe. CONSTITUTION:A combination jacket pipe 2 is formed by butt welding pipe- bodies made of copper or copper alloy to both ends of a central pipe part 5 made of noble metal. At that time, the jacket pipe 2 is formed by butt welding copper plates, etc. to both sides of a noble-metal plate to form a combination plate and rolling the plate in its bead direction to flatten it before forming it into a cylindrical shape. A core body 3 having the overall length smaller than the length of pipe 2 and projected parts 7, 7 formed at its both ends 6 is arranged at the end part of pipe 2. Further, end bodies 4a, 4b are welded to both ends of the pipe 2 by electron beam welding in a degassed state. In this way, the body 3 is prevented from producing intermetallic compounds as well as the bonding between the jacket and the core part is made firm to improve the yield of noble metal.
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