| 摘要 |
PURPOSE:To easily obtain the multilayer pipe having excellent adhesive strength by inserting the metallic pipe for the inner layer having higher yielding point than the material of the metallic pipe for the outer layer into the metallic pipe for the outer layer and by giving a load from the outer side so that the deformation of the metallic pipe for the outer layer exceeds the yielding strain thereof. CONSTITUTION:Both inner and outer pipes 11, 12 are simultaneously deformed with their compression by applying an external pressure 13 by performing a compressing with a press machine or roll, etc., from the outer side by inserting the metallic pipe 12 for the inner layer consisting of the material having higher yielding point than the material of the metallic pipe 11 for the metallic pipe 11 for the outer layer into the inner side of the metallic pipe 11 for the outer layer. Now, the deformation that exceeds the yielding strain of the pipe 11 for the outer layer and yet exceeds the yielding strain of the pipe 12 for the inner layer as well is given as the deformation by the external pressure 12. In this way, both pipes are closely fitted by the residual stress of the compression of the pipe 11 for the outer layer and the tensile residual stress of the pipe 12 for the inner layer.
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