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研发一种包含电加热和水冷却的快速热循环成型技术,以改善采用超临界氮气为物理发泡剂的注塑微孔发泡聚甲醛(POM)盖板的表面质量.通过优化设计,整个模具型腔表面的温度均匀性得到明显改善.定量研究模腔表面温度(T_M)对注塑微孔发泡POM盖板的泡孔结构和表面质量的影响,并分析相关的机理.结果表明,提高T_M可减小微孔发泡POM盖板的未发泡皮层厚度,但使其泡孔的直径少量增加、分布均匀性降低.使T_M从40提高至150℃可明显改善微孔发泡POM盖板的表面质量、减小表面粗糙度达85%,而不会明显增加成型周期.T_M取150℃时可消除常规注塑微孔发泡存在的制品表面缺陷.T_M要适当高(约130℃)以在改善微孔发泡POM盖板表面质量的同时保持良好的泡孔结构.
Developed a rapid thermal cycling technology that includes electric heating and water cooling to improve the surface quality of injection molded microporous foamed polyoxymethylene (POM) covers using supercritical nitrogen as a physical blowing agent. By optimizing the design, the entire mold The temperature uniformity of the cavity surface is obviously improved.The influence of the cavity surface temperature (T_M) on the cell structure and surface quality of the microporous foamed POM cover is quantitatively studied and the related mechanism is analyzed.The results show that increasing the T_M Can reduce the microporous foamed POM cover unfoamed cortical thickness, but to make a small increase in the diameter of their cells, the distribution of uniformity to reduce T_M from 40 to 150 ℃ can significantly improve the microporous foam POM cover Of the surface quality, reducing the surface roughness of 85%, without significantly increasing the molding cycle.T_M 150 ℃ can eliminate the conventional injection molding microporous foaming surface defects exist.T_M appropriate high (about 130 ℃) to Improve the surface quality of microporous foamed POM cover while maintaining a good cell structure.