how are cutting forces reduced during press operationsSoluti

how are cutting forces reduced during press operations?

Solution

In some cases it will be necessary to reduce cutting force to prevent press overloading.

A method to reduce press force is to grind the face of the horizontal plane.This reduces the area of contact during shear at any one time.

Providing shear angle also reduces shock to the press and smoothens out the cutting operation.

The shear angle should provide a change in punch length from 1 to 1.5 times the sheet thickness.

Double shear angle is preferred over single shear angle because it does not create lateral forces.

double shear angled punches should be concave to prevent stretching the material before it is cut.

to prevent distortion on the stock material
- for blanking operation the shear angle will be on the die member.
- for piercing operation the shear angle will be on the punch member.

Another method to reduce cutting force is to step punch lengths.Punches or groups of punches are made progressively shorter by about one sheet thickness.