The generation of the forming path with the springback compensation in the CNC incremental forming

Abstract

Aiming at the problem of the springback in the CNC incremental forming, a method for predicting the springback and generating the compensated forming trajectory was proposed based on the explicit and implicit finite element analysis. First, the middle surface of the simulated sheet metal part was reconstructed after the springback simulation with the coordinates of all nodes obtained from the numerical simulations, and the reconstructed middle surface was compared with the middle surface of the theory model to calculate the normal deviation values. Second, the theory model was offset with the unequal distances of the deviation values to generate the compensated facet and the forming path. Once more, the finite element analysis was done until the compensatory effect met the required precision. Meanwhile, aiming at the roughness of the compensated facet caused by the multi-compensation process, the smoothing method was given to guarantee the smooth of the forming path. According to the predicted result of the numerical simulations, three times compensation meets the required precision and the normal deviation value is decreased from 0.696 mm to 0.194 mm. The forming experiments indicate that the springback of the target part in Z direction is decreased from 1.107 mm to 0.427 mm. Therefore, the predicting and compensating method of the springback proposed in the paper is available, which can improve the forming precision of the sheet metal part.