| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of deep-drawing a square tube made of a metal plate improving productivity by fastening forming speed while taking the conditions of a die, etc. into consideration when applying the deep drawing of the square tube near the limit drawing ratio to a blank. SOLUTION: When performing the deep drawing of the square tube by forcing a punch into the metal plate to be worked fixed with a die and a blank holder, the blank the corner parts of which are cut is used. Under a condition that there is no bead having inflow inhibitory action of a flange material of straight side parts in the straight side parts between the die and the blank holder, punch forcing speed is fastened in the early stage of the working and the punch forcing speed is decreased compared with the speed in the early stage of the working at the point of time before the forcing position of the punch reaches the position of 2/3×forming height. COPYRIGHT: (C)2009,JPO&INPIT
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