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热流道时序阀浇口消除熔接痕研究 总被引:1,自引:1,他引:0
通过研究注塑件熔接痕的形成机理,阐述了热流道时序阀浇口对熔接痕的控制原理.以某轿车后保险杠注射成型为例,用CAE软件对充填过程进行模拟.结果表明,采用阀浇口时序控制技术不仅能很好地控制保险杠中的熔接痕,而且还能优化其它生产工艺,对保险杠的生产具有实际意义. 相似文献
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以某汽车仪表盘为例,设计了仪表盘的热流道顺序阀浇注系统和冷却系统。运用正交优化试验法结合Moldflow模拟分析软件,在不同顺序阀的开启时间和工艺参数条件下,对影响仪表盘注射成型质量的熔接痕和翘曲值标进行模拟优化,通过对这2个指标的极差分析,确定各顺序阀的开启时间和熔体温度、保压压力、保压时间对熔接痕和翘曲值的影响程度,并运用综合平衡法,综合评判最终获取最佳阀开启时间和组合工艺参数。试模结果表明,制件表面无明显熔接线且翘曲值符合装配要求。 相似文献
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综述了熔接痕位置预测、优化和控制技术的研究进展,介绍了填充过程熔接痕形成的数学模型。对数值模拟技术、数值模拟技术结合数学规划理论、阀式浇注和大型注射成型制品多浇口进料顺序控制技术等3种技术的分析流程、预测方法和应用实例进行了详细介绍,其中基于数值模拟技术和数学规划理论结合的熔接痕位置确定新算法是行之有效的熔接痕位置优化技术,已成为当前研究热点。随着该技术的日趋成熟,应用范围将逐渐增大。而阀式浇注和大型注射成型制品多浇口进料顺序控制技术的实施可以成功避免注塑件熔接痕的出现,在大型零件生产中具有广阔的应用前景。 相似文献
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为了消除空调导风板的熔接痕,以某空调导风板为研究对象,利用Moldflow模拟软件对其进行数值模拟。模拟结果表明,采用传统多浇口浇注时,空调导风板塑件表面易产生熔接痕缺陷,严重影响塑件的外观。采用顺序注射成型方法浇注,通过在原有热流道上安装可以由阀门装置软件独立控制的液压回路,实现多浇口顺序控制。经过方案优化,确定了3浇口的开启顺序和顺序开启时间,消除了空调导风板表面的熔接痕并改善了其表面的分子取向,提高了塑件的整体质量。将优化方案应用于生产实践中,满足塑件外观及性能需要。 相似文献
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Sequential injection molding using a valve‐gate‐controlled hot runner system has attracted attention for industrial applications in recent years. Because of the complexity of the operation mechanisms, a commercial valve gate usually delays for about 0.3–0.5 s once the valve‐opening command is given. The signal‐to‐operation delay is acceptable for the conventional injection molding of large parts. However, this operation delay limits its application to thin‐wall molded parts for computer, communication, and consumer electronics, for which the required filling time is very short. In this study, a gas‐driven fast‐response sequential‐valve‐gate system was developed for thin‐wall injection molding by the adoption of valve‐gate control performance. The characteristics and verifications of the valve‐gate opening were monitored with a charge‐coupled device (CCD) camera (nonmelt condition) and cavity pressure transducers and an accelerometer (melt‐filled condition). The influence of the tolerance between the inner piston and cylinder and the gas pressure on the valve‐gate opening was investigated in detail. Tensile bar parts 1 mm thick were used for the molding experiments. The delay time has been found to be intimately related to the response of the gas‐pressure delivery controlling the valve‐gate movement. In a nonmelt environment, the delay time of the valve‐gate opening decreases with increasing driven gas slightly. In a melt‐filled environment, the delay time is quite sensitive to the operating gas pressure because of the extra resistance between the shaft and the melt. A threshold pressure as high as 100 bar is required to keep the delay time below 15 ms. With the proper choice of the piston size and driven gas pressure, the delay time can be reduced to about 8 ms in a nonmelt environment and to about 12 ms in a melt‐filled environment. Molding using this improved system for sequential valve opening can provide thin‐wall injection parts without a weld line, and good cosmetic quality and better tensile strength require a lower injection pressure than molding using single‐gate and concurrent‐valve‐gate opening. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1969–1977, 2005 相似文献
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从熔接痕的成型机理出发,考虑了困气状况和熔合温度对熔接痕熔合质量的影响,提出一种以困气改善辅助提升熔接痕熔合质量的方法,建立了以“气穴面积”和“熔接痕处流动前沿温度”为熔接痕熔合质量指标的多目标评价体系,并构建了一种基于Kriging模型和非支配排序遗传算法(NSGA-Ⅱ)的多目标寻优策略,以实现工艺参数的择优选择。以多孔板熔接痕优化为例,选用拉丁超立方抽样(LHS)设计实验,建立并检验反映工艺参数和优化目标之间影响规律的Kriging模型,采用NSGA-Ⅱ确定多目标优化问题的Pareto前沿及其最优解。仿真及生产实验结果表明所建立的多目标优化策略能有效实现熔接痕的多目标优化,同时以困气改善辅助提升熔接痕熔合质量的方法效果显著。 相似文献
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挤出制品熔接痕的形成、结构分析 总被引:3,自引:2,他引:1
对挤出制品熔接痕形成的原理进行细致的分析,指出制品的熔接痕有“V形槽”及“弱连接”两种形式。熔接痕的强度及物理力学性能远远低于制品的其它部位。研究发现,熔接痕的结构与材料配方、挤出机机头模具及加工工艺参数均有关系。 相似文献
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针对某公司内某装置再生斜管卸料线根部短管包套的开裂事故进行了事故分析。分析认为包套开裂是由于水蒸气爆炸所致。常温状态下向包套内灌注的高耐磨浇注料含较多水分,在操作时温度达到700℃,水在包套有限空间内汽化为水蒸气,使包套内压力超过包套强度所致。计算了水蒸气的爆炸能量,针对原因给出了修复措施。 相似文献