| 摘要 |
PROBLEM TO BE SOLVED: To obtain a thin thickness core bar capable of securing a thinner thickness and a higher rigidity, even when an aluminum alloy stock is used. SOLUTION: A method for processing a rib in the internal surface of a tube stock 22' by dabbing a spinning roller on the surface of the tube stock 22', rotating the tube stock 22' supporting both ends of a hollow cylindrical tube stock 22', and when the ribs 26, 25a, 25b are formed in a plurality of places in the axial direction of the tube stock 22', contacting and removing the spinning roller on the surface of the tube stock 22', the other ribs except the rib 25a in the vicinity of the center between both ends supporting section are formed first and next, the rib 25a in the vicinity of the center is formed.
|
