外文翻譯--塑料注射模具設(shè)計(jì)及其熱分析-模具設(shè)計(jì)-全文預(yù)覽
【正文】 Contour plots of heat distribution at different time intervals. For the 2D analysis of the mould, time response graphs are plotted to analyze the effect of thermal residual stress on the products. Fig. 8 shows nodes selected for plotting time response graphs. Figs. 9–17 show temperature distribution curves for different nodes as indicated in Fig. 8. From the temperature distribution graphs plotted in Figs. 9–17, it is clear that every node selected for the graph plotted experiencing increased in temperature, . from the ambient temperature to a certain temperature higher than the ambient temperature and then remained constant at this temperature for a certain period of time. This increase in temperature was caused by the injection of molten plastic into the cavity of the product. After a certain period of time, the temperature is then further increased to achieve the highest temperature and remained constant at that temperature. Increase in temperature was due to packing stages that involved high pressure, which caused the temperature to increase. This temperature remains constant until the cooling stage starts, which causes reduction in mould temperature to a lower value and remains at this value. The graphs plotted were not smooth due to the absence of function of inputting filling rate of the molten plastic as well as the cooling rate of the coolant. The graphs plotted only show maximum value of temperature that can be achieved in the cycle. The most critical stage in the thermal residual stress analysis is during the cooling stage. This is because the cooling stage causes the material to cool from above to below the glass transition temperature. The material experiences differential shrinkage that causes thermal stress that might result in warpage. From the temperature after the cooling stage as shown in Figs. 9–17, it is clear that the area (node) located near the cooling channel experienced more cooling effect due to further decreasing in temperature and the region away from the cooling channel experienced less cooling effect. More cooling effect with quite fast cooling rate means more shrinkage is occurring at the region. However, the farthest region , Node 284 experience more cooling although far away from cooling channel due to heat loss to environment. Fig. 8. Selected nodals near product region for time response graph plots. Fig. 9. Temperature distribution graph for Node 284. Fig. 10. Temperature distribution graph for Node 213. Fig. 11. Temperature distribution graph for Node 302. Fig. 12. Temperature distribution graph for Node 290. Fig. 13. Temperature distribution graph for Node 278. Fig. 14. Temperature distribution graph for Node 1838. Fig. 15. Temperature distribution graph for Node 1904. Fig. 16. Temperature distribution graph for Node 1853. Fig. 17. Temperature distribution graph for Node 1866. As a result, the cooling channel located at the center of the product cavity caused the temperature difference around the middle of the part higher than other locations. Compressive stress was developed at the middle area of the part due to more shrinkage and caused warpa
畢業(yè)設(shè)計(jì)相關(guān)推薦
鄂ICP備17016276號(hào)-1