共查询到17条相似文献,搜索用时 140 毫秒
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浇注系统对注塑制品质量的影响及其优化设计 总被引:1,自引:0,他引:1
从注塑模浇注系统出发,分析了由于其设计不合理而引起填充不足、凹陷与缩痕、熔接痕、内应力等质量缺陷的原因,并针对这些原因从流道和浇口位置、数目、大小方面提出了相应的优化设计方案来提高注塑制品的表观质量和力学性能,解决某些靠调节注塑工艺或其它通用方法无法解决的问题,对指导注塑模浇注系统设计有很大帮助,提高了一次试模的成功率。 相似文献
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介绍了注塑件熔接痕的形成机理,分析了影响熔接痕强度的各种因素,从注塑工艺参数设定、模具结构设计等方面给出了消除熔接痕或提高熔接痕强度的措施。 相似文献
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分析了汽车盒体塑件的成型工艺,通过Moldflow软件对熔体的填充时间、注射压力、熔体前沿温度、气穴及熔接痕位置等进行了分析,根据模拟分析结果设计了一副三板式潜伏式浇口注塑模具,并对模具进行了合理的选材和热处理。结果表明,模具设计合理,运动平稳,成型的塑件尺寸精度高,表面无飞边、熔接痕、气穴等质量缺陷。 相似文献
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注塑成型工艺试验优化设计 总被引:1,自引:0,他引:1
针对注塑成型工艺中存在的缺陷,引入正交试验设计方法,进行模具结构和工艺参数的优化设计。以模具温度、保压压力、保压时间和模内冷却时间作为影响因素,以体积收缩率、缩痕指数和熔接痕长度作为评估指标,通过利用Moldflow软件模拟熔体在型腔内的流动,得到各工艺参数影响制品成型质量的趋势图。通过正交试验设计分析,得到各工艺因素对体积收缩率、缩痕指数和熔接痕影响的程度,结合极差分析、方差分析法综合比较各组试验模拟结果,获得最优化的工艺参数组合。 相似文献
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The polymer injection products produced by using the current injection molding method usually have many defects, such as short shot, jetting, sink mark, flow mark, weld mark, and floating fibers. These defects have to be eliminated by using post-processing processes such as spraying and coating, which will cause environment pollution and waste in time, materials, energy and labor. These problems can be solved effectively by using a new injection method, named as variotherm injection molding or rapid heat cycle molding (RHCM). In this paper, a new type of dynamic mold temperature control system using steam as heating medium and cooling water as coolant was developed for variotherm injection molding. The injection mold is heated to a temperature higher than the glass transition temperature of the resin, and keeps this temperature in the polymer melt filling stage. To evaluate the efficiency of steam heating and coolant cooling, the mold surface temperature response during the heating stage and the polymer melt temperature response during the cooling stage were investigated by numerical thermal analysis. During heating, the mold surface temperature can be raised up rapidly with an average heating speed of 5.4°C/s and finally reaches an equilibrium temperature after an effective heating time of 40 s. It takes about 34.5 s to cool down the shaped polymer melt to the ejection temperature for demolding. The effect of main parameters such as mold structure, material of mold insert on heating/cooling efficiency and surface temperature uniformity were also discussed based on simulation results. Finally, a variotherm injection production line for 46-inch LCD panel was constructed. The test production results demonstrate that the mold temperature control system developed in this study can dynamically and efficiently control mold surface temperature without increasing molding cycle time. With this new variotherm injection molding technology, the defects on LCD panel surface occurring in conventional injection molding process, such as short shot, jetting, sink mark, flow mark, weld mark, and floating fibers were eliminated effectively. The surface gloss of the panel was improved and the secondary operations, such as sanding and coating, are not needed anymore. 相似文献
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利用模流分析软件Moldflow Plastics Advisers(MPA)对空调机面板注塑模6种构型不同的浇注系统分别进行注射成型流动分析。通过模拟空调机面板在一定成型材料、成型工艺条件下注射成型流动时的温度场、压力场、速度场,获得熔体流动前沿温度、实际注射时间、实际注塑压力、气穴位置、熔接痕位置等参数;在此基础上比较流动结果,预测空调机面板成型质量,确定最优的注塑模浇注系统设计参数,成功地解决了大型塑料件成型时可能出现的充模不足、熔接痕明显等质量缺陷,为模具设计提供了科学依据。 相似文献
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The effect of melt temperature, ultrasonic oscillations, and induced ultrasonic oscillations modes on weld line strength of polystyrene (PS) and polystyrene/polyethylene (PS/HDPE) (90/10) blend was investigated. The results show that the increase of melt temperature is beneficial to the increase of weld line strength of PS and PS/HDPE blend. Compared with PS, the increase of melt temperature can greatly enhance the strength of PS/HDPE blends. For PS, the presence of ultrasonic oscillations can enhance the weld line strength of PS at different melt temperatures. But for PS/HDPE blends, the presence of ultrasonic oscillations can improve the weld line strength when the melt temperature is 230°C, but when the melt temperature is 195°C, the induced ultrasonic oscillations hardly enhance the weld line strength. Compared with Mode I (ultrasonic oscillations were induced into the mold at the whole process of injection molding), the induced ultrasonic oscillations as Mode II (ultrasonic oscillations were induced into the mold after injection mold filling) is more effective at increasing the weld line strength of PS and PS/HDPE blends. The mechanism for ultrasonic improvement of weld line strength was also studied. POLYM. ENG. SCI., 45:1666–1672, 2005. © 2005 Society of Plastics Engineers 相似文献
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Tensile and fatigue properties of an injection molded short E‐glass fiber reinforced polyamide‐6,6 have been studied as a function of two key injection molding parameters, namely melt temperature and hold pressure. It was observed that tensile and fatigue strengths of specimens normal to the flow direction were lower than that in the flow direction, indicating inherent anisotropy caused by injection molding. Tensile and fatigue strengths of specimens with weld line were significantly lower than that without weld lines. For specimens in the flow direction, normal to the flow direction and with weld line, tensile strength and fatigue strength increased with increasing melt temperature as well as increasing hold pressure. The effect of specimen orientation on the tensile and fatigue strengths is explained in terms of the difference in fiber orientation and skin‐core morphology of the specimens. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers. 相似文献
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This study was aimed at understanding how the process conditions affect the weld‐line strength and microstructure of injection molded microcellular parts. A design of experiments (DOE) was performed and polycarbonate tensile test specimens were produced for tensile tests and microscopic analysis. Injection molding trials were performed by systematically adjusting four process parameters (i.e., melt temperature, shot size, supercritical fluid (SCF) level, and injection speed). For comparison, conventional solid specimens were also produced. The tensile strength was measured at the weld line and away from the weld line. The weld‐line strength of injecton molded microcellular parts was lower than that of its solid counterparts. It increased with increasing shot size, melt temperature, and injection speed, and was weakly dependent on the supercritical fluid level. The microstructure of the molded specimens at various cross sections were examined using scanning electron microscope (SEM) and a light microscope to study the variation of cell size and density with different process conditions. 相似文献