FEA For The Clamping Unit Of An Injection Molding Machine And Optimization Design For The Stationary Platen

Injection molding occupies an important position in the plastic molding process. Injection molding machines are the main equipments which accomplish the injection molding. The clamping unit is an important component of an injection molding machine and tie bars are important parts of the clamping unit. It is necessary to obtain the stress distribution of tie bars since they are prone to fatigue damage. Platens are also important parts of the clamping unit. The weight of platens accounts for about more than70%of the total weight of an injection molding machine and the cost of them plays an important role in the whole cost of an injection molding machine. The existing design methods for platens are mainly based on the experience of designers. The structure and sizes of the similar ones are employed to obtain the design schemes of new platens. Therefore it is significant to optimize the design of platens based on the principle of trying to save material and improving the performance (or no performance reduction) at the same time.In this thesis, the research object is the clamping unit of an injection molding machine with800tons clamping force. The analysis of the clamping unit and the optimization design of the stationary platen are carried out with the help of FEM and ANSYS. The main content of the thesis is as follows:1. The basic research background and the significance of the research are pointed out. The previous work on the FEA of the clamping unit and the optimization design of the stationary platen done by former researchers are systematically summarized. The main research work of the thesis is listed.2. The basic theory of the FEM for contact problems is studied in depth which lays the groundwork for the FEA of the clamping unit and the optimization design for the stationary platen.3. The formulas of the speed ratio and the force amplification ratio are obtained after the kinematic analysis of the clamping unit. The finite element model of the clamping unit is simplified on the basis of the two above-mentioned ratios. The deformation, the stress distribution of the clamping unit and the pulling force supported by the tie bars are obtained after the FEA of the clamping unit is completed in ANSYS Workbench.4. The overall scheme of the optimization design for the stationary platen is put forward. The basic theory of the topology optimization for continuum is studied in depth. The topology optimization for the stationary platen is accomplished. Depending on the differences of the topology optimization areas, a total of four different topology optimization results are given and analyzed.5. The program and the mathematical model for the stationary platen shape-sizing optimization are given. The DACE (Design and Analysis of Computer Experiments) method is proposed to solve the shape-sizing optimization problem of the stationary platen. The design of experiments is obtained with the help of Uniform Design method. The Gaussian Kriging modeling technology is used to model the experiment results and the predicting capability of the Kriging model is evaluated. The basic method and process of the shape-sizing optimization using a surrogate model are given. The validity and reliability of the above method and process are verified by two typical numerical examples. The shape-sizing optimization for the stationary platen is completed in five different typical circumstances. New stationary platen structures suitable for practical application are obtained after appropriate modifications on the optimization results. The FEA for the new structures shows that the optimization effect is obvious.