Method and apparatus for forming a modified a cross-section wire material

摘要

A modified cross-section wire material is formed into piston rings such as oil-control rings for use in an engine. An apparatus of the present invention for forming the modified cross-section wire material has a forming unit (15) comprising in combination a non-powered pre-stage four-roll turks-head (16) and a powered post-staged four-roll turks-head (17). Disposed in tandem and downstream of the forming unit (15) is a non-powered finishing four-roll turks-head (21). A forming roll of the powered turks-head (17) has a diameter equal to or larger than 70 times as much as a height-of a flange of the material. In forming, the material is kept at a tension equal to or less than 300 N between the non-powered turks-head stand (16) and the powered turks-head (17), and at a tension of from 50 to 200 N between the forming unit (15) and the finishing turks-head (21).