| 摘要 |
PURPOSE:To obtain a transportation pipe of high performance without applying torsional stress to the pipe and preventing loosening of the end by winding a metallic strip around a plastic pipe while preforming to smaller diameter than outer diameter of the pipe. CONSTITUTION:In winding a metallic strip 3 by rotating a plastic pipe 2, a bend of smaller diameter D2 than diameter of D1 of the pipe is given to the metallic strip 3 by a roll 8 and adjustable rolls 9, 9'. Consequently, the metallic strip 3 becomes an internal pressure strengthening layer 4, and as there is no residual torsional stress in the pipe 2, the capacity of the pipe 2 is increased. Since the metallic strip does not get loose at the end of the pipe 2, lowering of strength of the end part is eliminated. |
