Research On The Law Of Springback In Bend-Forming With Titanium Alloy Sheet

A systematic analysis of the springback in titanium alloy sheet bend-forming was presented in this paper, it used the method which integrates finite element simulation and forming tests. The influence of direction of bending line on the springback was brought forward in a creative way, and the research on shape distortion phenomena in the bend-forming was performed.A unilateral tensile test with TA2M titanium alloy sheets for the mechanical capability of two different thicknesses (1.0mm and 2.0mm) has been performed, based on measured parameters, the U-shaped bend-forming process was simulated using PAM-STAMP software and the simulated result was verified by a series of forming tests. It also reveals the influences of different factors upon the precision in finite element simulation, including blank mesh size, adaptive refinement level and fictitious stamping velocity, and gains the influence relation-curves. In simulation,it is also found that the stroke have little effect to reduce the springback in stamping using rigid mould with supporting equipment.The test result have shown that the springback of TA2M titanium alloy sheets is evident, the thinkness of blank and relatively bending radius are the main factors to the springback: with the decreasing of thinkness and the increasing of relatively bending radius, the amounts of the springback is rising. A innovative verdict is brought forward in this paper:with the angle between bending line and rolling direction from 0°to 90°, the amounts of the springback is decrease,and the reason is also explained in this paper.It is generally considers that wide blank cross section is rectangle, but an exact definition about the shape of cross section was found from the bend-forming with titanium alloy sheet that the middle area of the blank is straight, and the two sides are slantwise. There was a local distortion at the end of bending line, and the distortion become much serious with the increase in thinkness and the decrease in bending radius.It is explored that the instruments to enhance the precision of bending parts, including beforehand equalize bending radius on punch, adjust the clearance between punch and die, camber the surface of punch and supporting equipment. A correct bending part was formed finally.