1、 Thick and high burrs around
The collapse angle and inclination angle of the shear section are large, while the middle part is obviously concave. The burr is not only high, but also the section is triangular. It cannot be removed without a file. This kind of stamping parts are generally defective.
Causes: (1) Excessive clearance; (2) In multiple grinding, the perpendicularity of the female die decreases, and for the full taper female die, it is due to the regrinding that the deviation appears.
terms of settlement
Narrowing the gap: (1) The shape is simple and can be reworked when the volume is small; (2) Stamping small and thin products can be hardened by electric spark; (3) Anneal the die, repair the cutting edge, and then conduct heat treatment and grinding; (4) Surfacing repair treatment; (5) Die base plate shall be used to press the insert, and processing shall be carried out after the blade is pressed out.
2、 Uneven height of burr
If the clearance is too large or too small, the height of burrs will increase. Among them, if the clearance is too large, triangular burrs will be generated, the thickness will increase, if the clearance is too small, the burrs will be thin and high, and secondary shearing will occur.
Causes: (1) The clearance is not consistent locally; (2) The edge collapse of the cutting edge causes local deviation; (3) The eccentric die will lead to inconsistent half of the burr height, poor die installation and poor guide post assembly; (4) The guide post is loose; (5) The accuracy of the press is poor.
Solution: (1) After deburring, the shape of the product shear section is not normal, because the gap is too large or too small locally, so it needs to be corrected. (2) The edge is locally worn, or due to poor quenching hardness, local edge collapse occurs, and the root of burr increases, so grinding is required. (3) It is easy to understand that the punch and the die are not concentric because half of the shear section is too large and half is too small. If the reason is that the die or guide post is not assembled well, it is OK to adjust it. However, if the position of the mold core changes in each stroke, it is because the mold assembly part is loose, and the mold core needs to be taken out for fastening. The correction port (4) will be out of alignment due to the thrust during stamping. When the side bearing block or guide plate is stressed, the guide pin must be used to ensure the accuracy. However, if the concentricity is not good after the guide pin is used, it is because of the quality difference of the guide pin. (5) The press is not good.
3、 Large burr (compression burr) at the shear section
The obvious tongue like part in the shear section is called compression burr.
Causes: (1) The gap is small as a whole, and there is a corner or notch at the edge of the die, (2) the back corner of the die is tapered, (3) the die hole is difficult to finish, and there is a rough surface, crushing the part with high crack surface.
Solution: (1) Adjust the clearance and grind the edge. (2) Remove the rear corner bright part of the female die caused by repeated collision with the grinding wheel. (3) Repair the part with serious contact spots on the vertical wall of the mold hole.
4、 Shear section presents linear reinforcement
The so-called linear reinforcement refers to the phenomenon that convex lines or concave lines appear at the shear section.
Causes: (1) There is a notch or curling edge damage in the die, (2) The crosspiece is ablated due to improper or insufficient lubricant selection, (3) Chip breaking or foreign matters are mixed in and stick to the die.
Solution: (1) The die is stuck in the centering operation, or the die hardness is too high, resulting in breakage or blade rolling. The former is better to repair and grind the bitten part, while the latter is better to reduce the hardness of the mold, otherwise, the chipping and blade rolling will occur again. (2) If the blank is stuck on the inner wall of the die due to the expansion of the blank caused by heating during the stamping process, and the die is scratched, the lubricant must be changed while using the rear corner. (3) If defects are caused by shrinkage or foreign matters melting on the inner wall of the die, measures must be taken to prevent dirt from adhering to the blank.