基于柔性装配偏差模型的汽车车身薄板零件公差设计

基于汽车车身柔性薄板零件装配建模方法,建立柔性薄板零件公差优化设计方法。根据柔性薄板零件测点装配偏差与各偏差源间的确定性模型,综合得到测点装配偏差的方差与零件制造方差和夹具定位方差之间的模型,以零件测点平均方差为公差设计函数,工序能力指数和零件制造方差比为约束函数进行零件公差优化设计,并采用车身后地板装配进行应用分析。结果表明,搭接焊接结构的零件公差设计需同步进行,对接焊接结构零件公差设计各自独立进行,而角接焊接结构的零件公差设计则先进行其中对接零件公差设计,然后进行搭接零件公差设计;搭接焊接结构中零件间刚度差异比较大时,刚度小的零件公差可以取相对更大的公差。

Tolerance design of automotive body sheet metal parts based on a compliant assembly variation model

An optimal tolerance design method of compliant sheet metal parts was proposed based on an assembly variation model of compliant sheet metal parts. The average variance model of all measurement points obtained from the determinate models of measurement points was adopted as the objective function of the tolerance design, and the process capacity index and the variance ratio of parts were the constraint functions. The rear floor assembly was used to validate the tolerance design method. The results showed that tolerance designs of parts were synchronously done in the lap welding structure, and independently done in the butt welding structure while in the corner welding structure the tolerance design of the butt part was firstly done and then that of the lap part was done. When there existed a very large rigidness difference between lap parts, the less rigidness part could adopt a bigger tolerance value.