【作者】 张雷；

【导师】 陈曦；

【作者基本信息】 浙江大学 ， 系统工程， 2008， 硕士

【摘要】 质量控制是塑料加工领域的重要研究方向。一个完整的注塑过程由充填过程、保压过程、冷却过程、塑化过程等组成。其中充填过程是注塑过程中最重要的阶段。充填过程中保持塑料熔体在模腔内匀速充填对产品质量有着重要影响。因此,本文主要研究如何最优化设定注射速度曲线,从而保持模腔内熔体的匀速填充。本文首先通过分析找出与充填位移相关的变量,并设计系列实验收集数据,离线建立递归神经网络模型。借助于这个神经网络模型,本文提出了三种不同分级方式对注射速度进行设定,并结合优化方法搜索最优注射曲线。其中方法一将注射速度曲线基于螺杆位移进行等间隔分级,并采用优化方法搜索各级速度变化斜率;方法二同样基于螺杆位移对注射速度进行分级,但是其各级距离不再固定不变,而是通过优化方法搜索;方法三通过一次开环实验,确定合理的分级位置,并依据这些位置参数,搜索出最优注射速度曲线。最后在多个不同形状的模具上进行了实验验证,并对三种方法的结果进行了分析比较。更多还原

【Abstract】 Quality control is of great importance for polymer processing. Injection molding, as an important polymer processing technology is a multistage batch process, including filling, packing-holding, cooling and plastication. Among them, the filling stage may contribute most to the final part quality. To ensure the uniformality of the product, a constant molding filling speed of the melt-front is anticipated. This thesis, therefore, focuses on the study of the optimal profiling method for uniform mold filling.A set of experiment design is first proposed to collect data, based on which a recurrent neural network model is developed to predict the average melt-front-length, which directly relates to the melt-front-rate, by using the measurement of screw injection velocity. Good performance in prediction is achieved by using on this model. Later, three different approaches are proposed for the optimal profiling of the injection velocity. In approach 1, the injection velocity curve is divided ten fixed intervals along the screw distance. Optimization is conducted to find the best velocity for each stage to ensure a constant melt-front rate. In approach 2, it is similar to that in approach 1, except that the interval number is not fixed. Based on that, both the interval length and interval number are optimized. In the third approach, an intelligent interval division method is proposed. Optimizations are later conducted to search for the optimal interval length. All the three approaches are tested on a number of molds with different shape. Comparisons are given through experiments.更多还原