Flanging Die Unbalanced Thrust

Posted by stephens on Mar 19, 2010 in Engineering Decisions, Equations | 0 comments

A while back, I blogged on how to quantify unbalanced thrust in cutting dies. Today, I would like to share the same for flanging dies.

Forces in a flanging die are equal and opposite. So what happens when flanging occurs on one side of a cutting component? Unbalanced thrust.

The issue with unbalanced thrust is should the flanging component be heeled or keyed to counteract the lateral force.

The first step to this decision is to quantify the magnitude of unbalanced thrust. The equation for unbalanced thrust in a flanging die is:

• Fut = Stan • (Fb / t)

where:

• Fut = Force of unbalanced thrust (kN)
• Fb = Force of bending (kN)
• t = Material thickness (mm)
• Stan = Span between upper and lower flange steel entry radii tangents (mm)

For example, a flange die with a span between upper and lower flange steel entry radii tangents of 12 mm (in other words, the linear distance of unsupported material when the upper and lower steels are at initial contact), bending force of 75 kN with a stamping that is 1.2 mm thick has a lateral force or unbalanced thrust of:

• Fut = Stan • (Fb / t)
• Fut =12 • (75 / 1.2)
• Fut =12 • 62.5
• Fut = 750 kN

This means that 750 kN of lateral force is acting on the flanging component. Lateral force, or unbalanced thrust is perpendicular to the flanging vector and not necessarily horizontal.