模流分析在大型塑料制件产品设计中的应用

Application of mould flow analysis in the design of large plastic parts

大型塑料制件具有尺寸大、结构复杂等特点。在模具设计制造之前,用模流分析软件对大型塑件进行成型预测非常有必要。以某液晶电视前框为例,采用Moldflow软件进行模流分析,结果显示:Z方向上的翘曲变形非常大。为了减小翘曲变形,对导致翘曲变形的三个原因(不均匀取向、不均匀冷却、不均匀收缩)进行逐一排查。排查过程中发现,调整浇口位置、冷却系统、保压参数均无法大幅降低变形量。最后,从产品数据本身入手,对制件侧壁厚度进行调整,翘曲变形量大为降低,降低幅度为2/3。结果显示:模具和工艺参数并非变形量大的核心原因,核心原因是产品壁厚不均匀、产品侧壁冷却过快。解决方案为:增加侧壁壁厚0.3 mm,使整个产品壁厚均匀。

Large plastic parts have the characteristics of large size and complex structure.Before the design and manufacture of the mould,it is necessary to use the mould flow analysis software to predict the moulding of the large plastic parts.Taking a LCD TV front frame as an example,the Moldflow software was used to analyze the mould flow.The results show that the warpage deformation in Z direction is very large.In order to reduce warpage deformation,three causes(non-uniform orientation,non-uniform cooling and non-uniform shrinkage)leading to warpage deformation were investigated one by one.During the investigation,it was found that adjusting gate position,cooling system and holding pressure parameters could not significantly reduce the warpage deformation of the parts.Finally,considering the product data,the thickness of the side wall was adjusted,and the warpage deformation was greatly reduced with a reduction of 2/3.The results show that the core causes of large deformation are uneven product wall thickness and fast cooling of the side wall,not the mould and process parameters.The solution is to increase the wall thickness of the side wall by 0.3 mm,so that the wall thickness of the whole product is uniform.