无尘板擦板体-板盖组件注射成型工艺分析

Analysis on Injection Molding of Dust- free Eraser

采用聚丙烯材料批量成型的无尘板擦用于学校的日常教学中可以改变硬质黑板擦字扬粉尘。该板擦的板体、板盖为异形件，为减少成型产品的模具套数和降低成本，设计一套一模两腔的塑料注射模成型板体与板盖，但是流道平衡问题很难解决。为确保该板擦的板体-板盖组件成型质量和要求，首先利用Moldflow软件的浇口位置分析模块确定板体、板盖的合理浇口位置，接着利用流动平衡分析模块进行平衡约束条件的设置，并进行迭代计算，确定各分流道合理的截面尺寸，以达到流动平衡的目的。分析结果表明，采用这一方法，可以明显改善熔体在型腔内流动的不平衡性，防止过保压等由于流动不平衡造成的缺陷出现，可提高制品的成型质量，降低生产成本，缩短生产周期。

The dust-free erasers made of polypropylene can be used in the school daily teaching without any dust from traditional hard eraser and chalk. The bodies and covers of the erasers are special - shaped parts. To reduce the number of the molding product die and the cost, we designed a plastic injection mould of one die with two cavities to mold the bodies and plates at the same time, but it is difficult to solve the problem of runner balance. To ensure the quality of the components of the eraser bodies and covers and meet requirements, firstly, the gate position analysis module of Moldflow software is used to determine the reasonable gate position of the body and the cover. Then the flow balance analysis module is used to set up the balance constraints and calculate iteratively to determine the rea- sonable sectional dimensions of each diversion channel in order to obtain flow balance. The result shows that the method will improve the melt flow imbalance in the cavity and the excessive pressure and other defects due to flow imbalance are preventable, so it can improve the product quality, decrease the cost and shorten the production cycle.