| In recent years,with the guidance of national policies,the trend of the auto industry has begun to rise,and new car companies have entered the market,making the competition in the automotive industry fierce particularly.Along with the fierce competition,each enterprises pays more attention to model development and cost reduction and efficiency.Automotive coverings are an indispensable part of automotive production,and their highefficiency and low-cost manufacturing process is one of the directions that companies are committed to explore.The shape and structure of automotive coverings are complex,and they are difficult to be formed in sheet metal parts.There are many factors affecting the forming quality,such as process parameters,mold design,operating environment,etc.Therefore,ensuring the robust quality of the cover part production process is crucial.After the part is formed,springback phenomenon will inevitably occur due to the internal stress release,which will lead to reduction of dimensional accuracy.Therefore,it has become one of the hot research problems to restrain the amount of springback of the part on the basis of ensuring the robust production of automotive cover parts.In this paper,in order to solve the above problem,we take the automotive front panel as the research object,combine approximate model and robust optimization to explore the robust design of part quality during the stamping process of automotive cover parts,and studies on springback compensation for the springback phenomena.The main research content of the thesis is divided into the following parts:(1)According to the analysis of the forming process of the front panel structure,a reasonable stamping process is formulated,and defining the shape of the drawing model surface and the original blank is introduced.The impact of three layout methods of drawbeads on the forming quality is emphasized.Finally,a finite element model is constructed to realize the simulation of the forming performance of the front panel,and potential quality problems after the front panel forming are evaluated for the first time to provide direction for the subsequent optimization design.(2)Research on robust design for stamping forming of automotive coverings.To optimize the forming quality of the front panel,the thinning rate and springback are selected as key indicators for quality evaluation,and the key process parameters are selected as the influence factors by sensitivity analysis.In the process of optimizing the forming quality,the optimal Latin hypercube is used to construct the sample space and fit the kriging approximate model,and the multi-objective problem is solved by combining the Neighborhood Cultivation Genetic Algorithm(NCGA)to obtain the deterministic optimal solution of the process parameters in the global space.Through robust analysis of the deterministic optimal solution,it is found that the quality is greatly affected by the fluctuations of process parameters.Therefore,it is decided to continue improving the robust quality of the front panel to a level of 6 sigma by using robust optimization design.(3)Aiming at the problem that the springback of the front panel is still not controlled within ±1mm after the quality robust optimization,a geometric node displacement compensation method is considered to optimize the drawing-die surface to reduce the springback of the front panel after forming by comparing the springback compensation method.After multiple iterations,the springback of the part reached the convergence condition,and the drawing-die surface after springback compensation is derived.Combined with finite element analysis,it is found that the springback is successfully controlled within± 1mm.Finally,the trial production shows that the 6sigma robust optimization combined with springback compensation optimization method can significantly improve the forming quality of the front panel,while ensuring that the robustness of the parts in mass production. |
PDF Full Text Request