The Study Of Plastic Snap-fit Design And The Development Of Snap-fit CAD Application Module

Snap-fit attachment is the important mode of coupling during assembly. Because there is no need for snap-fit to add additional parts as well as it can be easily assembled that it is gradually displacing screw to be the most important attachment in several situations.In traditional course of developing snap-fit, designers commonly take advantage of the snap-fit from similar product, by enlarge or reduce the geometrical dimensions in scale to fit the request. It is obvious that the design is far from accurate. In additional, snap-fit can be designed by the references provided by the plastic companies. Because of few snap-fit types they offer and quite a lot of equations and charts the references contain, it is obviously over loaded with details if references are used during design.Aim at the problems above, Snap-fit Design Module was developed in the article. The function of snap-fit designing and 3D snap-fit model exporting was integrated in it and the course of designing a snap-fit was greatly simplified by the Snap-fit Design Module. Snap-fit Design Module was developed during the four steps as follows. First, several kinds of commonly used snap-fits were by collected and generalized, second, the key dimensions and mechanical properties of them were studied, third, one of typical kind of snap-fit was choosen and further studies were made to get the equation of max strain during assembly, at last, by using the tool of VC++ and Pro/Toolkit, the Snap-fit Design Module based on Pro/E was developed.Taking the machine of POS for example, designing the snap-fits of it by taking use of Snap-fit Design Module. The results got from Snap-fit Design Module would be proved by the snap-fit analysis which was made by ANSYS. Through that, the effect of Snap-fit Design Module would be examined.Because the assumptions were used to get the equations of snap-fits,the results got by the equations couldn't be exactly accurate,but to offer the valuable references for the geometrical parameters for the design of snap-fit. The results got from the snap-fit design model can completely satisfy the demand of the practical project. At present, the exactly results of snap-fit design can not be got by simple formulas.