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Unformatted text preview: are generally two different weld-guns used for spot welding; the position gun and the balanced gun. The position gun has a fixed lower weld electrode. During welding, sheet metal parts are pushed against the lower electrode despite the initial deviation. The balanced gun applies an equal magnitude of force over both sides of the weld electrodes. This means that the flanges of the sheet metal parts will meet in an equilibrium position. When the welding is complete, the assembly is released from the fixture. Then, the assembly springbacks due to forces introduced during welding and to imperfections such as part and fixture variation. It is this springback deflection that needs to be controlled and analyzed during the development stages. 1.2. Dimensional Variation Modeling Over the past years, different methods have been presented to predict dimensional variation on sheet metal assemblies. Most of the methods are based on the Finite Element Analysis (FEA). [Liu and Hu, 1997], presented a model to analyze the effect of component deviations and assembly springback on assembly variation by applying linear mechanics and statistics. Using FEA, they constructed a sensitivity matrix for compliant parts of complex shapes. The sensitivity m...
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- Spring '10
- The Land