Papers by Keyword: Springback Compensation

Abstract: Cold formed sheet metal parts made of advanced high-strength steels (AHSS) offer a high potential for a lightweight, durable and economic design. However, manufacturing dedicated, high-strength parts with cold forming technologies such as conventional deep-drawing often results in unacceptable shape deviations due to elastic springback after unloading the part from the forming tools. Therefore, various springback compensation methods have been established to ensure dimensional quality of such sheet metal parts. At the Institute for Metal Forming Technology (IFU Stuttgart), deep-drawing with alternating blank draw-in was developed in this context as a new approach to reduce springback and enhance cold forming of AHSS sheet metal parts. Presented work provides numerical sensitivity analysis as well as experimental studies about this new forming method. The asymmetric and alternating blank draw-in, which is changed within a multistage forming process sequence, results in an alternated bending over tool radii and leads to a beneficial stress superposition in the part wall area with reduced springback phenomena. Compared to conventional deep-drawn sheet metal components, springback of a benchmark part geometry could thus be reduced over 75 % by a three-stage forming process with an optimized blank draw-in kinematic.

Abstract: Springback is an inevitable phenomenon in multi-point forming, it affects the forming accuracy seriously. The precision of formed parts can be improved by modifying the die profile. The method of springback compensation for multi-point dies which formed cylindrical parts was studied utilizing theoretical analysis, numerical simulations and experiments. In order to accurately form cylindrical parts with specified parameters, the springback compensation formula of multi-point dies was studied. The upper and lower dies were adjusted according to the formula. Comparing the formed parts obtained from numerical simulation and experiment with the target part, the results show that this method can control the forming error within 1 mm guiding the forming process of cylindrical parts in practice, the problem of shape error caused by springback was solved effectively.

Abstract: Along with the automobile lightweight development, aluminum has become the focus of its own material characteristics. The aluminum alloy products with high efficiency, high quality and low cost are the guarantee of competitive advantage. High quality die surface is directly related to the product quality, cost, production efficiency, die life and so on. In this paper, the stamping process of two kinds of aluminum alloy products was simulated by Auto Form. The method of setting blank holding force and spring back compensation was introduced. At the same time, the setting of parameters such as die fillet, friction coefficient and draw bead was described in this paper. Finally, the optimization of die surface design was achieved by simulation.

Abstract: High springback and limited forming limits of modern high strength steels are a big challenge in manufacturing engineering. Both aspects are crucial in sheet metal bending processes. Different modifications of the air bending process have already been developed in order to reduce springback and also to increase the forming limits of materials. The innovative process of incremental stress superposition on air bending, developed at the IUL, is an alternative to conventional processes. Studies of this new process alternative show a positive effect on the considerable reduction of the sheet metal springback and extension of forming limits. Using the principle of incremental stress superposition leads to several advantages compared to conventional bending processes like die bending, bending with an elastomer tool, or three point bending. The bending force and, therefore, the consumed energy during air bending with incremental stress superposition are much lower. This paper presents the new process alternative and shows the latest investigation results.

Abstract: In view of the high precision requirements of the more complex stamping parts of the springback law, this paper put forward a rebound closed loop control system model based on the improved Fourier transform. First of all, starting from the product model, it use the method finite element analysis and the forming process parameter optimization for the initial mold design, and then to measure the mould and stamping products and assess the springback error. Finally, eliminating the springback error through two iterative loops to complete the final mold fixed compensation. Experiments show that the system can complete the mould shape correction effectively by using the model and realize the springback compensation of complex stamping parts.

Abstract: Springback and limited forming limits of modern high strength steels are a big challenge in manufacturing engineering. Both aspects are crucial in sheet metal bending processes. Different modifications of the air bending process have already been developed in order to reduce springback and also to increase the forming limits of materials. A new method (the incremental stress superposition on air bending) has been developed. Studies of this new process alternative show a positive effect on the springback behavior. In order to investigate the potential of this process a comparison with other already established bending processes have been carried out. A possible process control to extend the forming limits has also been investigated.

Abstract: Springback of sheet forming is became a serious issue which we must be solved before froming process. The springback system was designed by visual studio2010, and displayed by OSG graphic developed tools. Besides, the system named Comsystem also used some FEM files from PAM-STAMP2G code. These files are put into Comsystem , then the working surface is formed and a new forming die is designed. The vector compensation algorithm and compensation factor have been used. The method to determine the second compensation factor is proposed. The system has great significance not only in controling the springback compensation but also in reduceing the production cost.

Abstract: The performance of the aluminum alloy makes it the most popular lightweight materials for the automobile manufacturers. However, due to the disparity on the crystal structure,it has the higher springback values compared with steel. In order to solve the problem, we put forward a new springback compensation method based on displacement compensation principle and the principle of curved surface fairing design methods. Though full cycle simulation and calculate springback value for each working procedure, then generate the springback compensation surface. The methods practical application effect is good.

Abstract: In recent years, finite element analysis technology has been applied in Aircraft sheet metal manufacturing and digital manufacture field. It has become an effective way to solute Aircraft sheet metal precise manufacturing and received extensive attention. Chengdu Aircraft Company used finite element analysis in Rubber bladder forming for the development of aircraft. Parts rough lumber, forming way, tooling structure, forming pressure and springback compensation has been pre-determined. Finite element analysis of Rubber bladder forming shortened the process preparation cycle, and improved the part forming quality and the ability of the development and production.

Abstract: Springback compensation of Multi-point forming (MPF) was analyzed in the paper based on the ideal elastic-plasticity and linear hardening material models. The calculation formulas for adjusting radius of MPF die, both single-curvature and double-curvature, were obtained. Cylinder and spherical surfaces were formed by MPF equipment. Experimental results show that the errors between formed surface and target shape are within 5%. Moreover, when using formulas derived from linear hardening model, it is found that the formed surface is more close to target contour, and the presented formula can be used to determine the adjusting radius of MPF die in practice.