| 摘要 |
PURPOSE:To improve machining efficiency by outwardly projecting the butt part of an undercut ring unit and cutting the projected part together with the undercut part. CONSTITUTION:A piston ring material A is formed into a belt like body having a sliding contact surface 1 on its outer periphery and an undercut part 2 on its bottom end, by means of drawing, etc., which is wound and formed into a coil and, then, is cut at every wind, being formed into a ring unit B. And, the butt parts 3 of the both cut ends of each of the ring units B are bent so as to be outwardly projected from the ring unit B and, after that, the projected parts 4 may be ground, to become a circle of a defined diameter of the ring unit B, producing a piston ring body C. Accordingly, a piston ring which is excellent in dynamic characteristics such as wear resistance, etc., can be efficiently manufactured without hindering productivity. |
