| 摘要 |
PURPOSE:To produce a clad pipe of superior quality and cost by inserting a metal round bar having a coefft. of thermal expansion higher than that of inside and outside pipes into the inside pipe, and heating the same. CONSTITUTION:An inside pipe 1 is inserted into an outside pipe 2, and further a heat resistant metal round bar 3 of a coefft. of thermal expansion higher than that of outside pipe material and inside pipe material is inserted into the inside pipe 1. These are then pressed from both ends to tightly adhere the bar to the inside pipe, after which both end grooves 4 are welded 5 and fixed, thence these are heated to a diffusion welding temp. The heat resistant metal round bar 3 thermally expands to forcibly expand the inside pipe 1 which then contacts the outside pipe 2 and this develops a pressing force, causing the outside pipe 2 and the inside pipe 1 to undergo diffusion welding. At this time, the round bar 3 to be inserted is formed into a wedge shape with taper so that the insertion is made easy and the round bar adheres firmly to the inside pipe. In addition, this makes its removal upon ending of the welding easy. Air vent holes 7 are provided to the outside pipe 2 to prevent defects owing to the remaining of air. |
