| 摘要 |
PROBLEM TO BE SOLVED: To provide a multi-layer pipe which can reduce an amount of copper or copper alloy used to form an inner pipe as less as possible and a simple manufacturing method thereof. SOLUTION: A thin-walled pipe 20 made of copper or copper alloy is inserted into an outer pipe 10 with high hardness made of a material other than copper, an expanding tool 30 whose diameter is a little smaller than the inner diameter of the outer pipe, and at the same time, whose hardness is larger than copper or copper alloy is inserted into one opening end of the thin-walled pipe and extracted from the other opening end, as a result, the thin-walled pipe is press- fitted on the inner face of the outer pipe. An expanded part whose diameter is larger than the inner diameter of the outer pipe may be provided on one opening end of the thin-walled pipe. The expanding tool may be constituted by a plurality of connected nearly spherical bodies. COPYRIGHT: (C)2003,JPO |
