| 摘要 |
PROBLEM TO BE SOLVED: To attain correct hydraulic forming by filling a pressure fluid in a blank, and maintaining a required internal pressure at the time of the blank being bent into a required shape. SOLUTION: A trailing arm 10 is manufactured by applying fluid pressure to the interior to hydraulically form into complicated shape. Both ends of an annular blank are sealed tightly, and a pressure fluid is injected therein. In the state of a pipe wall being supported by the pressure fluid, a pipe is bent in required complex curvature. The pipe is then placed in a die cavity of shape substantially coinciding with the complex curvature of the pipe, and the internal pressure is intensified. The pipe wall is thereby expanded outward to enter in a secondary cavity so as to substantially fill the die cavity. When the internal pressure is intensified to expand the pipe wall, the bulge of one side part near the outer end 16 of the arm 10, the bulge of an intermediate place for forming a spring seat 34 a pair of bulges at both side parts of a linear part 14 are respectively formed. |
