Causes and analysis of warping of stamping parts

[Virgo]

[Feilong Jiangli Edition]When the material is in contact with the punch and the concave die, it must first stretch and bend, then cut and tear. Due to the action of various forces such as drawing, bending and lateral extrusion, the wavy shape of the material exhibited on the part is produced, and the part warps. The causes of warpage are as follows:
（1）Large blanking clearance
When the clearance is too large, the drawing and bending force of the workpiece is large and easy to warp in the blanking process. The improved method can be tightly pressed with punches and blanking plates during blanking, and the sharp edge can be maintained.
（2）Inverted cone at the entrance of the die cavity
When the workpiece passes through a small part, the periphery is compacted to the center, resulting in bending.
（3）Warpage produced by the structural shape of the workpiece
When the shape of the workpiece is complex, the shear force around the workpiece is not uniform, so the force from the surrounding to the center is produced, which makes the workpiece warpage. The way to solve this problem is to press the material.
（4）Warpage produced by internal stress of materials
When the material is rolled and rolled, the internal stress will be moved to the surface after blanking. The warpage will appear. The solution is to straighten the machine through the leveling machine when unwinding.
（5）Warpage due to poor oil, air and poor contact
When there is oil, air and other compressive parts between the die and the parts, the parts will warp, especially thin and soft materials. But if the oil is evenly coated and the exhaust holes are set, the warpage can be eliminated. The surface between the workpiece and the die is sundry and easy to cause warpage.
Warpage is also caused by poor contact surface during blanking.