| 摘要 |
PROBLEM TO BE SOLVED: To easily manufacture a hollow square cylindrical metallic tube which is short in the length of a side and made thin without increasing the number of manufacturing processes. SOLUTION: By passing a hollow cylindrical metallic tube 13 having the outer peripheral length which is equal to that of the hollow square cylindrical metallic tube to be formed through a roller die 14 in which two sets of a pair of rollers in opposition are arranged into a cross shape and pressurizing the hollow cylindrical metallic tube 13 toward the center from four side directions, the cylindrical tube is formed into the hollow square cylindrical tube 16 without reducing the area. The center part of the outer peripheral surfaces of respective rollers 15 constituting the roller die 14 has slightly dented circular-arcuate curved surface 15a and both end parts continuing to the middle part has a slope 15b inclined toward the inside. COPYRIGHT: (C)2011,JPO&INPIT |
