1.What is the core operation for increasing the blank holder force by adjusting the die to wrinkle cold-rolled coil stamping parts?
Adjust the air cushion pressure of the press or remove some of the balance blocks to increase the clamping force on the pressing surface.
Increase the flow resistance of the sheet material, slow down the material flow rate, and alleviate wrinkling of the flange or sidewall.
2.How to adjust/correct mold clearance?
Check the clearance between the punch and die. If the clearance is too large (e.g., >1.2 times the material thickness), use the punch as a reference to repair and weld the die to correct the clearance to 0.9~1.2 times the material thickness.
It eliminates localized material buildup caused by uneven gaps, allowing for more uniform material flow and effectively eliminating surface wrinkling.
3.How to increase the resistance of draw beads?
Increase the height of the drawbar, or replace the round bar with a square bar or drawbar with a drawbar that provides greater resistance.
It strengthens the control of external material inflow and changes the internal stress state of the material, making it suitable for wrinkling parts with deep or complex shapes.
4.How to improve mold surface and lubrication?
Inspect the die's draw beads, fillets, and other areas for wear. Without causing cracks, reduce the lubricant's oiliness or clean the die surface to increase friction.
If the material surface roughness is too low or the lubrication is too good, it will cause the material to become "too slippery" and wrinkle. Increasing friction can effectively reduce the material flow rate.
5.How can you quickly diagnose wrinkling issues?
First, confirm the material: Quickly check the material grade and surface condition. If the material surface is too smooth (low roughness), or if a new batch of material has been used (e.g., from DC04 to a common material), this is likely the cause.
Next, check the mold: Observe the shape and location of the wrinkles.
If the wrinkles are on the flange or blank holder surface, prioritize trying direction 1 (increasing the blank holder force).
If the wrinkles are on the internal surface of the part, and obvious uneven gaps are visible, prioritize checking direction 2 (mold clearance).
If the wrinkles are on the sidewall of a complex deep-drawn part, direction 3 (draw beads) is often key.
Finally, consider process adjustments: If the above methods are ineffective, and there is excess material accumulation at the wrinkle location, consider adding "suction ribs" in inconspicuous locations to absorb excess material, or creating process gaps to change the material feed direction.