| 摘要 |
The die cavity has a flat base from which the surrounding wall rises. The cavity wall is formed in a die block to produce an open-topped cavity. At least a major part of the cavity base is formed by the head face of a plunger which is a close fit in a bore of the die block, so that the cavity is leakproof. The plunger can be retracted to a lower position in which the head face is flush with the base plane of the cavity. Alternatively the plunger can be advanced to a higher position in which the head face is at least as high as the top edge of the cavity. - Pref. the die cavity is slightly conically convergent towards its base. A coaxial, parallel bore in the base houses the ram head. The ram is displaced by an auxiliary fluid power cylinder independent of a main cylinder used for bringing together the die and punch. |
