Study On Drawing Law Of Box Part With Concave Contour

The complex parts with concave contour are widely used in vehicle and mechanical manufacturing fields, however the investigation for the forming law of such parts is relatively less. This project investigated the drawing law of the parts with concave contour, thereby enriching the forming theory of basic structure as well as providing law for cracking and wrinkling during drawing process of the parts with concave contour and the corresponding methods to solve the quality issues.Dynaform is used to analyze the forming law of the parts with concave contour,the change law of the wall thickness and strain of such parts, forming deficiency and the stress distribution. Single variable method is used to analyze the influencing factors on the wall thickness reduction of the parts with concave contour.Orthogonal test is applied to analyze whether the size factor and technology factor on forming force of the parts with concave contour are significant. It is investigated that the effect of size factor and stamping condition on winkling of the parts with concave contour. Through drawing experiment, the distribution of wall thickness of parts with blank shape and drawing height is obtained, and this distribution matches the results of simulation experiment.This investigation indicates that during drawing of the parts with concave contour, the thickness of blank on the diagonal line of angles of punch-nose and cavity block reduce fast, and the reduction in the central region of diagonal line is more. Meanwhile the blank flow near the interior angle of punch-nose is less, which allow blank to accumulate thereby leading to winking.Bigger two angles of the parts with concave contour is good for forming process, while bigger drawing height is against the forming process, 7.5 mm wall length can achieve best forming result; bigger friction coefficient, blank holder force and drawing rate are bad for forming process.Through orthogonal test, it is concluded that the effects of drawing height and friction coefficient on the forming of parts with concave contour are prominent.The influence of exterior angle of the parts with concave contour is little, while bigger interior angle led to serious winkling. Otherwise, bigger wall thickness,drawing height and friction coefficient led to unobvious winkling. The blank with round shape is bad for forming the parts with concave contour.The obtained wall thickness distribution and winkling phenomenon of the parts with different blank shape and drawing height match the results of simulationexperiment; the reliability of numerical simulation is confirmed by few experiments.