| 摘要 |
PROBLEM TO BE SOLVED: To provide a forming method with which forming of a pipe is easy while bucking is hard to occur and light weighting can be achieved in such a pipe member as to especially receiving a shaft direction load from two end portions. SOLUTION: Outer periphery of a steel pipe P is clamped with a clamping die C at a mid point position and a pipe end part is protruded for a given length from the clamping die C. The pipe end face is pressed in a shaft direction with a pressing face Bp while constraining an inner periphery of the extruded part by inserting an inner periphery constrain part Bs of a punch B into the extruded part. Then, at about the middle point position of the extruded part of the pipe P is bulged so as to be bent outside for forming a double structure flange part f by collapsing the bulged part as it is.
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