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Efficient planning and numerical analysis of industrial hemming processes
Igor Burchitz,David Fritsche,Goran Grundmann,Matthias Hillmann 한국소성가공학회 2011 기타자료 Vol.2011 No.8
Hemming is a forming operation used in the automotive industry to join inner and outer components during the assembly of closures. These are typically opening parts of the body-in-white with additional requirements to their visual appearance. A suitable production concept of hemming operation which satisfies quality, capacity and cost requirements is determined during hemming planning activities. A digital tool to facilitate these activities and minimize the amount of trial and error iterations in try-out phase is presented in this paper. This tool can be used to define process plan, active tool surfaces and suitable process parameters for both die hemming and roll hemming operations. In case of early feasibility studies, when the die layout of the drawing operation is still not available, 3D part geometry is used directly to develop the concept of hemming process. Advanced validation studies, aimed at process optimization and controlling defects associated with hemming, can be based on complete simulation of all forming operations. Validation and analysis of developed concepts of hemming operation is done using the standard AutoForm-Incremental solver. Submesh strategy and special algorithm for contact description between inner and outer parts were implemented to ensure that accurate simulation results can be obtained within reasonable calculation time. Performance of the new software tool for hemming planning and accuracy of simulation results are demonstrated using several simple benchmarks and a real industrial part. It is shown that the new software tool can help to secure the efficient production launch by providing adequate support in try-out phase.
ANALYSIS OF THE PERMANENT DEFORMATION OF AUTOMOBILE HOODS
H. J. LIM,Y. B. LIM,N. KIM 한국자동차공학회 2016 International journal of automotive technology Vol.17 No.2
One factor that determines the quality of an automobile’s appearance is its appearance integrity, which means that the degree to which an automobile’s physical appearance coincides with its mechanical quality. The painting process of an automobile can cause the permanent deformation of its hood, which lowers its appearace integrity. The painting process is comprised of the dipping process and the oven process. In the dipping process, pressure caused by the flow of fluid can cause the deformation of the automobile hood; in the oven process, the thermal deformation of sealers can cause the deformation of the hood. In an effort to increase automobiles’ appearance integrity, this study identifies the major causes of deformation and predicts the types of deformation occurring in each process. The numerical model of a hood is established using the stiffness scanning method and analysis, and deformation in the dipping process is confirmed using Finite Elements Method (FEM). Sealers are hypothesized as the main reason for deformation in the oven process, so a study of the sealers is conducted to predict the deformation occurring after the oven process. Further, through a thermal property experiment and viscosity test, we are able to deduce the properties of sealers that cause deformation. This study also examines the effects of hood deformation in the oven process using numerical analysis and compares the degree of deformation caused by pressure and heat. The results show that the absolute value of deformation in the dipping process is greater than that in the oven process. Moreover, it is shown that deformation can occur bi-directionally in the oven process, and the quantity of mastic sealer does affect the degree of deformation.