| 摘要 |
On one previously specified outer surface of the four outer surfaces of a rectangular wire for manufacturing a piston ring that is C-shaped in two-dimensional view, polishing lines are formed along a direction that differs from the polishing lines on the other outer surfaces. The cross-sectional shape of the rectangular wire has a rectangular shape delimited by a pair of long sides and a pair of short sides. When the outer surfaces comprising each of the pair of long sides form the upper surface and lower surface and the outer surfaces comprising each of the pair of short sides form the inside surface and the outside surface, polishing lines along a first direction can be formed on either the upper surface or the lower surface and polishing lines along a second direction differing from the first direction can be formed on the other of the upper surface and lower surface. |
