关键词: 渐进成形, 铝板, 壁厚, 锥形件, 正弦定理

Abstract: The wall thickness variations of aluminium conical parts were analyzed during incremental forming with different processing parameters. The application scope and accuracy of wall thickness variation by the sine law for incrementally formed aluminium conical parts was studied through comparing the variations and differences of measured wall thicknesses for different processing parameters with the values predicted by the sine law. The results show that the wall thickness variations of conical parts during incremental forming have three stages, i.e. wall thickness thinning stage, wall thickness pick-up stage and wall thickness stable stage. The extremely easy rupture points of sheet metal are “the minimum value points” between the thinning regions and pick-up areas. Through comparing the measured and the predicted wall thickness values, it is found that the wall thickness measured in the stable region is close mostly to the predicted wall thickness values of sine law. The application scopes of wall thickness variation sine law for incrementally formed aluminium conical parts are in the stable regions. Work hardening produced in the primary processing may result in difficult deformations at joints of the sheet metals in secondary processing with higher average error rates. Most measured wall thicknesses in the stable regions for incrementally formed conical parts are 1%~2% lower than the predicted values of sine law. The feed amounts have greater influences on the accuracy of sine law. Furthermore, the wall thickness empirical equations of the wall thickness thinning region, pick-up area and stable region for conical parts were established through Levenberg-Marquardt algorithm and global optimization calculating methods.

Key words: incremental forming, aluminum sheet, wall thickness, conical part, sine law