基于注塑制品收缩率预测的模具型腔尺寸生成方法研究

【作者】 郑清娟；

【导师】 王敏杰；

【作者基本信息】 大连理工大学 ， 机械制造及其自动化， 2003， 硕士

【摘要】 注塑成型制品由于其具有质量轻并具有优良的综合机械性能而在机械、电子、航空等领域得到广泛的应用，与此同时，制品的精度要求也越来也高，形状越来越复杂。采用一般的平均收缩率方法来确定模具型腔的成型尺寸，已难以满足精密注塑成型制品的精度要求。现有的注塑模CAD/CAM/CAE系统在建立模具型腔表面三维几何模型方面一般都是先建立注塑件的几何模型，然后给注塑件几何模型一个比例系数1+S(S为收缩率)，对注塑件几何模型进行比例放大，得到模具型腔表面的三维几何模型。本文分析了现有的注塑模CAD/CAM/CAE系统在建立模具型腔表面三维几何模型方面的不足以及注塑成型制品的收缩率影响因素，提出基于注塑成型制品的收缩率预测来生成注塑成型模具型腔基本尺寸的方法。注塑成型制品表面的离散点及对应的收缩率数值已知，通过建立制品尺寸与模具型腔尺寸的换算方法，得到与塑料制品表面各点相对应的模具型腔表面离散点。由于双三次B样条曲面具有局部可调性，在工程中得到广泛应用，本文采用双三次B样条插值曲面进行模具型腔表面曲面片拟合，用Visual C++6.0以及OpenGL编程实现；利用反求工程软件Imageware Surfacer进行分块曲面片的拼接，实现在注塑模CAD/CAM/CAE系统中的模具型腔表面曲面建模。所建立的模具型腔表面几何模型，由于考虑了注塑成型制品表面各处的收缩率差异情况，因此可以减少由于收缩率取值误差过大造成的塑件误差，提高模具设计的成功率和合格率。最后结合实例来说明上述方法的应用。更多还原

【Abstract】 On account of light weight and good comprehensive mechanical properties , injection-molded parts get increasingly widely used in such industries as mechanical, electronics, aviation and so on. Meanwhile, the precision of plastic parts get more high and the shapes is also get more complicated. Using average shrinkage rates of injection-molded parts to decide the dimension of mold cavity can not satisfy the demand of high precision injection-molded parts. The existing injection mold CAD/CAM/CAE system generaly build the 3-D geometric model of injection-molded parts, then give a scale coefficient 1+S(S means the average shrinkage rates of injection-molded parts) to the 3-D geometric model of injection-molded parts to zoom in to build the 3-D geometric model of mold cavity. Aiming at it’s shortage, the paper analyze the influence factor of shrinkage rates of injection-molded parts, a new method based on the prediction of shrinkage rates of injection-molded parts to decide the dimension of mold cavity is also brought forward in this paper. The scatter points of molded parts and the corresponding shrinkage is known. By building the conversion method between the dimension of injection-molded parts and dimension of mold cavity, we can get the scatter points on the surfaces of mold cavity. In order to establish the three-dimension geometric model of mold cavity in injection mold CAD/CAM/CAE system, using cubic B-spline curve surface to interpolation those scatter points. Use Visual C++6.0 and OpenGL to make the program. After the fitting of the single cubic B-spline curve surface, the outstanding reverse engineering software Imageware Surfacer is used to complete the connetion of single cubic. B-spline curve surface. Thus, the three-dimension geometric model of mold cavity surfaces is established. For the difference shrinkage of injection-molded parts is considered in the model of mold cavity, so it can reduce the deviation that caused by shrinkage, then improve the rates of success and the rates of eligibility of the mold design. In the end, an example is used to show the method that the paper has proposed. In order to validate the method, analysis of deviation is also put into use. The result shows that it can satisfies the demand of precision..更多还原