Reducing Spring Back in Sheet Metal Forming Using Compression and Shear

Abstract

Incremental sheet forming is a sheet metal forming technique in which sheet metal is formed into a final work piece through a series of small deformations in the part. Though this process does take longer than a standard sheet forming process, it is beneficial because it requires no dedicated tooling, reducing the cost per part and making it a good solution for low volume sheet metal part production. However, the presence of spring back leads to geometric inaccuracies in the final part dimensions. This research project aimed to explore methods to reduce spring back in sheet metal forming through analytical and experimental methods. Analytical models were created, and experimental data was collected for each of three conditions: simple bending, bending with normal compression, and bending with shear compression. Results showed that increasing the compressive load during sheet metal bending reduces spring back, but that introducing shear stress produces no discernible difference in spring back than standard normal compression. Spring back could be modeled analytically if appropriate calibration was applied to theoretical models. This entails that closed loop systems could be implemented in an incremental sheet forming process using analytical methods. The primary advantage of analytical methods in such a system is that they would be much faster computationally than finite element methods. T