| 摘要 |
PURPOSE: To give stability of form, anti-buckling characteristic, and rigidity against a lateral force applied to a slitted pipe by specifying a ratio of external diameter to pipe thickness, form of corrugation, and welding. CONSTITUTION: In a method of making a spirally or circularly corrugated pipe by welding a slitted pipe in a way that a weld line is formed in a longitudinal direction, and using a circular corrugating tool eccentrically rotating with respect to the pipe axis, (a) the slitted pipe is made with a ratio of outer diameter D to pipe thickness S at 100 or larger, (b) the slitted pipe is welded by a laser or a TIG-pulse welding, and (c) the corrugation is formed at a ratio of flute top T or corrugation pitch Tp to flute bottom t at 3.75 or smaller. An electric cable 20 consists of a cable core 21 and a cable jacket 22 and the jacket is a corrugated pipe and further a jacket of synthetic material is given. |
