| 摘要 |
<p>With a view to eliminating the surface streak-like defective burr of a nearly triangular section resulting from the forcible infiltration of a metal component into the joint of top and bottom dies of a sectional forming die when a tubular ferrous blank set in the above die provided with a convave inner forming recess corresponding to a desired joggled pattern on the surface of said tubular blank is subjected to the bulge forming step by the aid of two opposed mandrels of a whole circular section forcibly inserted into the tubular blank to form the above joggled pattern on the surface thereof, the present invention proposes the arrangement of two identical sectional forming dies side by side but different in their orientations from each other and using two opposed mandrels of the same mutilated circular section in place of the whole circular one.</p> |
