Spring Back Compensation

Due to the plastic-elastic forming of a workpiece, there is a spring back at the end of a bending process. The spring back has to be compensated to achieve an accurate result. Usually that is realized by overbending the material correspondent to the height of the spring back. That means for the practical side of the bending process, the bending former enters deeper into the bending prism.

In the case of complex tools the spring back has to be already considered in the construction phase. Therefore complex software simulations are used. Frequently this is not enough to deliver the desired results. In such cases practical experiments are done, using the trial-and-error plus experience method to correct the tool. However the results (workpieces) are only stable, if all influencing factors are the same. (ETH Zürich, p. 67)

This mainly includes:

The list of factors can be continued.

Practical Example: Electronic bending tools with spring-back compensation

Electronic Bending Tool with integrated angle measurement and spring-back compensation

The electrical industry mostly uses flat materials of copper and aluminium producing equipment for the electrical industry, especially switchgear and busbar production. Properties between two different charges of those materials vary strongly having a critical influence on the dimensions.

Already in the 60's Dieter Ehrt invented the bending technology for flat material which measures each bend angle and provides spring back compensation. This gives the bend angle of flat materials true accuracy.

This is attained by using bending prisms with electronic angular measurement technology. The principle is easy, but smart: While bending two flat bolds supporting the material turn around. The bolds are directly connected to the anglular sensors. A computer or rather the machine control then calculates the required final stroke. The spring back of every bend is compensated regardless of material type.

If the measuring accuracy is 0.1º, a high angle accuracy of +/- 0.2º is achieved instantly with the first work piece without any rework. Because no adjustments are required, material waste amounts and setup times drop considerably. Even inconsistencies within a single piece of material are automatically adjusted.


See also

References