| 摘要 |
An apertured part is pressed in a single cycle with no separate slug shearing operation. The press ram and bolster each contain fixed aperture forming punches which extend coaxially and slidably through piston like die supports, each of which is backed by a hydraulic fluid chamber. Separate systems control the fluid pressure in the two chambers so as to cause the dies supports to slide in one direction relative to the punches initially, then quickly in the other direction to shear the slug formed between the ends of the punches away from the part. The ram chamber is maintained at a high pressure throughout the first half of the stroke, while the bolster chamber begins at a low pressure and is allowed to rise to a higher, intermediate pressure that is still lower than the bolster chamber. Thus, the ram die support pushes the bolster die support down. However, when the pressure differential is removed, the two die supports quickly move up together over the fixed punches, shearing the slug out of the part.
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