免喷涂金属质感改性塑料模具与制件结构优化

Optimization of Mould and Part Structure for Spray-Free Metallic Plastics

针对免喷涂金属质感改性塑料在实际应用过程中经常存在的熔接线及流痕问题,从模具与制件结构的角度对免喷涂金属质感改性塑料表观缺陷进行了优化验证研究。结果表明,制件结构宜采用简单化结构设计,应尽量规避筋位、孔、壁厚突变结构的使用;加大浇口尺寸可以大幅减弱流痕及熔接线,其中采用轮辐式浇口是较好的改善手段;应尽量减少筋位及盲孔结构的使用,如果无法规避,应根据制件结构适当调整筋位及盲孔结构,筋位走向宜垂直熔体流动方向且筋位结构尽量作减薄(或镂空)处理;当筋位壁厚/制件壁厚<0.4时,制件外观面基本不会出现外观缺陷,随盲孔壁厚/制件壁厚比值不断增大,盲孔位置(或壁厚变化处)外观面缺陷不断减弱;表面蚀纹处理对缺陷有很好的遮盖作用,其中拉丝皮纹的遮盖效果要好于网格皮纹。

For the problems of welding line and flow mark in the practical application of spray-free metallic plastics,the apparent defects were optimized and verified from the perspective of the mould and part structure.The results show that,simple structure design should be adopted for the structure of the parts,such as unnecessary rib,hole,wall thickness mutation and other structures should not be used as far as possible.Increasing the gate size can greatly reduce the flow mark and welding line,and the spoke gate is a better way.The using of rib and blind hole structure should be reduced as far as possible,if it cannot be avoided,the alignment and thickness arrangement should be adjusted appropriately according to the structure of the part.The orientation of rib should be vertical to the melt flow direction and the thinned(or hollowed out)treatment for the rib structure should be done as far as possible.When the wall thickness ratio of rib/part is controlled at<0.4,the apparent defects do not appear.The apparent defects at blind hole(or wall thickness change position)also decrease with the increase of wall thickness ratio of blind hole/part.The surface etching treatment has a good covering effect on the defects,and the effect of brushed finishing texture is better than that of grid texture.