Overforming straight flange wiper bending operations in metal stampings through inside bend radius and height configuration on punches
Springback in metal stamping bending has been a problem for metal stamping manufacturers. A progressive die was built and run on a mechanical press through bending on a 304 Stainless Steel material to see if this radius and height are a factor to the springback value. ^ This experiment attempted to overbend by using radius ratios of 1.5 and 2.0 radius ratio of the traditional method with 10 different heights to see the effect on the response of the angle being how far it is from 90 degrees. For validation purposes the radius ratios of 1.75 and 2.25 with three different heights were used to see if the tendency shown is accurate. The experiment found that the bigger the radius and the lower the height the closer the parts would reach the target bend of 90 degrees. The experiment did not produce the perfect 90 degree bend but it was improved from a 1.478 degree angle (average) by traditional methods to a .6049 degree angle (average) with the 2.25 radius ratio and the smaller height, by overbending to accommodate for that springback. By seeing the tendencies shown in the experiment, with an even bigger radius and a smaller height, the target should be reached. ^ This is beneficial because a low cost tool will exist since this geometry is already ground into the punches that will be performing the wiper bending in the progressive metal stamping industry, the only difference would be the size of the radius. ^
Robles, Salvador, "Overforming straight flange wiper bending operations in metal stampings through inside bend radius and height configuration on punches" (2004). ETD Collection for University of Texas, El Paso. AAIEP10600.