| 摘要 |
A upsetting method and an upsetting device capable of efficiently increasing the diameter of a bar-like material at at least two positions. In the method, a plurality of guides (31) and (32) having insertion holes (34) are prepared, and the bar-like material (1) fixed to a fixed die (20) is inserted into the insertion holes (34) of the plurality of guides (31) and (32) in order and held therein. Next, while the material (1) is axially pressed by a punch (50R), the plurality of guides (31) and (32) are integrally moved in a direction opposite to the moving direction of the punch (50R) in a mutually fitted state to increase the diameter of the first exposed part (4) of the material (1) exposed between the first guide (31) disposed on the forefront among the plurality of guides (31) and (32) and the fixed die (20). After the first guide (31) is moved, the second guide (32) disposed on the rear side of the first guide (31) among the plurality of guides (31) and (32) is moved in the direction opposite to the moving direction of the punch (50R) to increase the diameter of the second exposed part of the material (1) exposed between the both guides (31) and (32).
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