Investigation of the effect of springback in deep drawing with finite element method

One of the basic problems in sheet metal forming by deep drawing is springback. In this study, this determination is investigated. Springback prediction and compensation is one of the most important factor which affects the desired piece shape, time and cost gains. Finite element simulation focused on evaluating aluminum deep drawing processes and developing appropriate parameters for these processes. The deep drawing method is the forming of the sheet between the pieces made of cast iron or steel material of suitable form, which are generally complementary to each other, called staples and matrices, with a pulling force in the middle part and a high pressing force on the edges. While the desired shape is given to the piece by the applied shaping method, deformations occur in the piece. In this thesis, two pieces which are suitable for deep drawing were determined. The parameters to be used in deep drawing analysis such as type of material, size of mesh, structure of mesh, thickness of sheet metal, holding force, speed of punch were determined. Analysis were done for aluminum pieces. Deep drawing analysis was performed by changing the values entered into the program for the holding force and the speed of the punch. The animation files formed as a result of the analyzes were played at the Hyperview and the forming limit diagram was drawn. Forming limit diagrams were investigated. Many techniques are used to assess the formability of sheet materials. One of these techniques is the forming limit diagram. By looking at this diagram, the deep-drawing process is evaluated whether the treated piece is wrinkled or torn. Spring back analysis were not applied to torn pieces. Spring back analysis was applied to the parts considered appropriate after the evaluation. When the load applied while shaping sheet materials, the material tries to recover elasticly and thus return to the preforming form. This event is called springback. The relevant file for the springback analysis was transferred to the program. Spring back analyzes were completed. The resulting animation files were played at Hyperview. The displacement value was read from the result screen. The displacement value gives the amount of spring back occurring in the deep drawn piece. At the lowest displacement value, the amount of springback is minimal. The force and velocity values used during the deep drawing of this part were determined as the best parameters. The results of the analysis with the lowest spring back and the results of the analysis with the maximum spring back were compared. It is determined how much improvement has been achieved as a result of this study. The lowest springback amount was removed from the highest springback amount, divided by the maximum springback, multiplied by a hundred and the percentage improvement rate was calculated. The improvement rate for the first piece was 57,26% and the improvement rate for the second piece was 95,28%. When the values of the parameters were changed, the amount of spring back changed was monitored and compared. In order for the value of the springback to be the lowest, the values of these parameters should be interpreted. In order to reduce spring back, deep drawing can be recommended at smaller force values. In the deep drawing process, a force and velocity should be preferred so that the wrinkles do not occur. Very high speeds and force values are not suitable.