| 摘要 |
PURPOSE:To reduce the strokes of the press plate of the following stage and to perform a precise forging by forming an initial groove and gap for rolling reduction of the press plate in the following stage in case of pressing a raw material in a die space. CONSTITUTION:The spherial part of a crank journal is formed by the pressure application of a press plate 18 with inserting a raw material 16 into the die space consisting of an outer die 10 and lower die 14. An initial groove 16a for the press plate rolling reduction of the following stage is formed by providing a projection part 18a on the part opposing to the inner width of the crank arm of the center part of the press plate 18, also a gap 19 is formed between a liner 12 and the material 16. The press plate 20 having the same thickness with the inner width forming dimension T of the crank arm coinciding with the initial groove 16a is then pushed in and the material 16 is filled into the gap remaining in the die space. In this case the stroke of the press plate 20 can be reduced by the size (l) and the depth of the initia groove 16a and the forging load can be remarkably reduced.
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