Mold Design For A Hopper Pedestal Based On CAE

This project is an injection mold designing for a plastic hopper pedestal which is used in a new food machinery. The hopper pedestal is not only the upper end cover of a gear pump but also base under a hopper which contains the food raw material paste. The hopper pedestal will be made of the non-toxic, corrosion resistant plastic PMMA and molded by injection molding. Its structure is not completely symmetrical and there are concaves outside it.These problems must be solved during design the mold, such as clamping mold force can balance the expanding mold force, the mold can part and pull the side core at long distance, and the molding product don’t deform and occur weak weld. In order to improve the quality of mold design, reduce times of trial and repair mold, lower the cost of mold development, this paper carries through the mold design of the hopper by the method of combining CAD/CAE.With the development of computer technology, injection molding CAE technology has obtained the unprecedented development. MOLDFLOW as a professional flow analysis software,which is developed by AUTODESK, can simulate the whole process of injection filling and predict the quality of plastic product. Engineering technical personnel can be helped with evaluation and optimization of mold design by MOLDFLOW and control plastic product quality.First, this paper used MOLDFLOW to analyse several different injection schemes.The optimal design of location and number of the gate aims at filling time, bend deformation and weld lines, gas hole and the temperature at flow front. The significance and the reasonable division method of grid generation are discussed in detail. And then the reasons affecting plastic bend deformation are analyzed. The analysis of the filling, flowing, cooling, warping is taken by using MOLDFLOW. A reasonable cooling system has been designed in the target of minimizing the warpage.MOLDWIZARD specialized in injection mold design is an application module of UG software and contains a perfect parting function. For ordinary plastic parts, designing injection mold is very convenient by using MOLDWIZARD. Because of MOLDWIZARD does not contain of the mold base of halves mold, it can not be used in the whole process of the injection mold design of hopper pedestal. Aiming at the particularity of the hopper structure, an innovative method which combine MOLDWIZARD with three-dimensional modeling is used to design components of the mold and the goal of side parting and pulling core moving in both directions is achieved. In the meantime, the design of the spur also has distinguishing feature, which solved uneven force caused by unsymmetrical structure of plastic part.In the end, we examine the rationality of the mold structure and related parameters by virtual assembly and computer simulation the process of opening mold, clamping and ejection. At the same time we discuss the method of creating the movement simulation of injection molds and the solution of problems that may occur.Using CAD/CAE to develop the injection mold changes the inevitable result that repeated test and repair the mold caused by the traditional mold design method. Through the numerical simulation of filling process and the computer simulation of opening mol, clamping and ejection this method is more suitable for today’s fierce competed market. Design scheme will be optimized, mold development costs will be reduced and mold design quality will be improved.