医用电子检测仪支架双色成型模具设计

Design of dual-color forming mould for medical electronic detector bracket

设计了1副双色注塑模具用于某医用电子检测仪支架双色塑件的成型。依据塑件不同材料不同颜色的生产要求,第一射基础件选用聚碳酸酯(PC)成型,第二射插片体选用PC/丙烯腈-丁二烯-苯乙烯塑料(ABS)成型,第二射材料熔体温度比第一射材料低35℃,确保第二射成型能顺利进行。在分别制定了第一射、第二射成型工艺的基础上,设计了塑件成型的双色模具,双色模具采用旋转式结构,由两副子模具构成,两副子模具都采用两板式模具,浇注系统都采用冷流道+热嘴形式。针对有滑块机构的双色模具在第二射成型时易产生飞边问题,设计了一种双色模具三角截面斜导柱第一射免抽芯滑块机构,在该机构中,通过将常用圆柱形斜导柱改进为三角截面斜导柱、增设弹销,以及将斜导柱孔改进为“U形槽”等措施,使第一射成型时侧抽芯滑块免于侧抽芯,从而确保了第二射子模具模腔封闭的严密性,将塑件的成型品质合格率提高到99%以上。

A pair of dual-color mould was designed for the molding of a dual-color plastic part of a medical electronic detector bracket.According to the production requirements of different colors and different material for the plastic parts,the first injection basic plastic part was formed using polycarbonate(PC),and the second injection insert body was formed using PC/acrylonitrilebutadiene-styrene plastic(ABS).The melting temperature of the second injection material is 35℃lower than that of the first injection material,ensuring the smooth progress of the second injection molding.On the basis of formulating the first injection and the second injection molding processes respectively,a dual-color mould for plastic part molding was designed.A rotary structure was used in the dual-color mould,which was composed of two pairs of sub-moulds.Two-plate moulds was used for the two pairs of sub moulds,and the form of"cold runner+hot nozzle"was used for gating system.In response to the problem of flash in the second injection molding of the dual-color mould with a slider mechanism,a design of first injection non core-pulling slider mechanism with triangular section angle pin for the dual-color mould was proposed.The measures such as improving the commonly used cylindrical angle pin to a triangular section angle pin,adding a spring pin,and improving the angle pin hole to a"U-shaped groove",etc.,were adopted in the mechanism,then the side core-pulling slider during the first injection molding was prevented from side corepulling,ensuring the closure tightness of the second injection mould cavity and improving the molding quality qualification rate of the plastic parts to over 99%.