Scrap is essentially the reverse image of a shape hole. That is, the same position is just the opposite. By checking the waste, it can be judged whether the upper and lower die gaps are correct. If the gap is too large, the scrap will show rough undulating fracture surfaces and bright banded areas.
Excessive gaps create large rolls and holes with torn edges, giving the outline a little protruding and thin edges. A gap that is too small creates a ribbon that is slightly curled and torn at a large angle, resulting in sections that are more or less perpendicular to the surface of the material. The ideal scrap should have a reasonable crushing angle and a uniform bright band. This keeps the stamping pressure as small as possible, creating a neat round hole with the smallest burr. Therefore, in order to prolong the service life of the mold, the clearance should be increased considering the quality of the finished hole.
Selection of plastic mold gap. The die gap is related to the die material and thickness. Not having a reasonable interval can lead to the following problems:
(1) If the gap is too large, the burr of the stamping part is relatively large, and the stamping quality is poor. If the gap is too small, although the punching quality is good, the die wear is serious, the die life is greatly reduced, and the punch is prone to breakage.
(2) If the gap is too large or too small, it is easy to cause bonding to the punching material, resulting in the formation of strip-shaped material during punching. If the gap is too small, a vacuum is likely to be formed between the bottom surface of the punch and the plate, and the waste material will rebound.
(3) Reasonable clearance can prolong the life of the mold, the discharge effect is good, the burr and flanging are reduced, the plate is kept clean, not scratched, the number of knife sharpening is reduced, the plate is kept flat, and the punching positioning is accurate.
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