Tips for Enhancing Efficiency and Mold Durability in CNC Turret Punch Press Operations

The operation of CNC turret punch press punching machines is a technical job, and usually receives professional operation training before starting work. However, trained workers can only be considered to be proficient in operating CNC turret punch press punching machines. To play CNC turret punch press punching machines well, it requires a lot of experience and continuous discovery and summary in long-term work. Here are a few brief introductions for everyone:

CNC turret punch press
CNC turret punch press

1. CNC Turret Punch Press Punching Machines Need to Ensure Appropriate Mold Clearance

The mold gap refers to the sum of the gaps on both sides when the punch enters the lower mold. It is related to plate thickness, material, and stamping process.

Choosing appropriate mold gaps can ensure good punching quality, reduce burrs and collapses, maintain the flatness of the sheet metal, effectively prevent material carryover, and extend the lifespan of the mold.

By checking the condition of stamping waste, it can be determined whether the mold gap is appropriate. If the gap is too large, the waste material will have rough and undulating fracture surfaces and smaller bright surfaces. The larger the gap, the greater the angle formed between the fracture surface and the bright surface. During punching, curling and fracture may occur, and even a thin edge protrusion may appear. On the contrary, if the gap is too small, the waste material will have small angle fracture surfaces and larger bright surfaces.

When performing local stamping such as slotting, step punching, and shearing, the lateral force will cause the punch to deflect, resulting in a small gap on one side. Sometimes, excessive edge offset can scratch the lower mold, causing rapid wear of the upper and lower molds.

When the mold is stamped with the optimal clearance, the fracture surface of the waste material and the bright surface have the same angle and overlap with each other, which can minimize the punching force and minimize the burrs in the punching hole.

CNC turret punch press

2. Timely Sharpening Can Effectively Extend the Service Life of Molds

If the workpiece has excessive burrs or produces abnormal noise during stamping, it may be due to mold passivation. Check the punch and lower die. When the edge wear produces a circular arc with a radius of about 0.10mm, it is necessary to grind the edge.

Practice has shown that frequent micro grinding instead of waiting until necessary grinding before grinding can not only maintain good workpiece quality, reduce punching force, but also prolong the life of the mold by more than twice.

CNC turret punch press

Besides knowing when to sharpen the mold, mastering the correct sharpening method is particularly important. The rules for mold grinding are as follows:

1) Use sintered alumina grinding wheels with a hardness of D~J and a grain size of 46~60. It is best to choose a grinding wheel suitable for high-speed steel grinding.

2) When grinding, the punch is vertically clamped in the V-shaped groove or fixture of the magnetic chuck of the surface grinder, with a grinding amount of 0.03-0.05mm each time. Repeat grinding until the punch is sharp, and the maximum grinding amount is generally 0.1-0.3mm.

3) When the grinding force is high or the mold is close to the grinding wheel, adding coolant can prevent the mold from overheating and cracking or annealing. High quality multi-purpose coolant should be selected according to the manufacturer’s requirements.

4) The grinding wheel has a downward feed rate of 0.03-0.08mm, a lateral feed rate of 0.13-0.25mm, and a lateral feed rate of 2.5-3.8m/min.

5) After grinding, use an oilstone to polish the edge, remove burrs, and grind out rounded corners with a radius of 0.03-0.05mm to prevent the edge from cracking.

6) Demagnetize the punch and spray lubricating oil to prevent rusting.

CNC turret punch press

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