| 摘要 |
A tube consisting of ductile metallic or plastic material is provided with circumferentially complete corrugations, helical grooves and/or axially parallel grooves while it travels between two universally movable bearings so that it can flex sideways without any appreciable elongation or hardening of its material. The grooves or corrugations are formed by tools having concave tube-engaging faces and rotatably mounted in a holder which orbits about the tube between the two bearings. The tools can be fixedly or adjustably mounted in the holder; in the latter instance, a single set of tools can be used to form circumferentially complete corrugations, helical grooves or axially parallel grooves. |
