| Injection molding is a batch production processing method that some complicated shape components used. In the forming process of injection mould the main force in the mold plastic is melt pressure. As the important part of the injection mould, mould cavity is the appearance forming parts of plastics product. Due to the decay resistance and release needs, add cavity wear, bonding occurs in the part surface, fatigue and fracture often begin from the surface, so that cavity surface quality will directly affect the quality of plastic parts and mould life.This paper firstly elaborates the mould failure and fatigue reliability research situation, take use of injection mould design method and theory, combined with plastic parts shape and various performance parameters of cavity design, the design gives the basic structure of injection mould cavity, use UG for modeling tools to design the cavity and the whole mold three-dimensional model. And on the basis of the finite element method and fatigue reliability analysis theory, establish the finite element analysis model of injection mould cavity. Take injection mould cavity as the research object, based on the finite element analysis software ANSYS, this paper analyzes the working pressure, the maximum deformation and stress conditions of the mould cavity.Based on pressure measurements of injection mould cavity of each plastic products with different wall thickness. Summed up the change of cavity pressure over each period of time in a molding cycle. Thus according to all kinds of injection molding parameters which have already been identified, including injection mould cavity pressure curve of similar products (volume and wall thickness). To estimate fatigue load spectrum of injection mould cavity that still in design stage. Combined with mechanical properties of cavity materials related, by using ANSYS/FE-SAFE to generate materials S-N curve that conform to the requirements of the whole analysis. In the end, on the basis of the static analysis results, take use of ANSYS/FE-SAFE for cavity fatigue analysis, conclude fatigue failure weak area, then, calculate the fatigue life of the mould. Take use of probability-strength model of mechanical reliability design theory to simulate the reliability calculation of the cavity.Contrast the level of analysis results under the cavity surface roughness indicate that the surface roughness is of great influence to the fatigue life of injection mould cavity, and with the increasing of the roughness, the fatigue life of cavity and fatigue safety factor all have very big decreasing amplitude. By finishing the strength calculation and fatigue analysis, according to the stress and strain condition and fatigue life value, take the structure and manufacturing process into account, choosing an appropriate strength and toughness matching mould, through the proper heat treatment and surface treatment, to redesign and improve, so as to reduce test time and design cost, shorten the design cycle. |
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