医用无影灯架注射模设计

Design of injection mould for medical shadowless lamp holder

结合某医用无影灯架塑件注射成型的要求,选用30%玻纤增强聚对苯二甲酸丁二酯(PBT)/丙烯腈-丙烯酸酯-苯乙烯(ASA)材料用于成型。由于塑件为圆盘+双侧圆柱筒结构,针对其浇口难以开设的难题,设计了2个热浇口用于塑件模腔的浇注,保证了模腔充填的可靠性。针对塑件两侧都设置有深壁圆柱筒难以自动脱模的难题,采用分步脱模的办法,先用弹簧推动的定模顶杆在模具第一次打开时辅助推动塑件从型腔镶件中脱模,而后通过模具的第二次打开驱动动模侧的圆柱形芯从塑件中抽出,最后由注塑机顶杆推动顶针将塑件顶出而实现完全自动脱模。模具模腔布局为1模1腔,开模有两次。模具的开模顺序由设计的弹夹顺序控制器进行控制。复位弹簧也做了应用改进,除了用于推板的复位外,还用于模具模板的顺序打开控制。复位杆顶端加装耐磨垫块和底端加装橡胶垫等措施都有利于提高模具寿命。在此设计方案下制造出的模具保证了塑件的成型精度为MT3级,良品率达95.6%以上。

Based on the injection molding requirements of a medical shadowless lamp holder,30%glass fiber reinforced polybutylene terephthalate(PBT)acrylonitrile acrylate styrene(ASA)material was selected for its molding.In response to the difficulty of opening gates due to the disc+double cylindrical structure of the plastic part,two hot gates were designed for the pouring of the plastic part mould cavity,ensuring the reliability of mould cavity filling.In response to the difficulty of automatic demolding of plastic parts with deep walled cylindrical cylinders on both sides,a step-by-step demolding method was adopted.Firstly,a fixed mold top rod pushed by a spring was used to assist in demolding the plastic part from the cavity insert when the mould was first opened.Then,the second opening of the mould drived and pulled the cylindrical core on the mould side to extract it from the plastic part.Finally,the top rod of the injection molding machine was used to push the top needle to eject the plastic part,achieving complete automatic demolding.The mould cavity layout was the first mock examination and one cavity,and the mould was opened twice.A clip sequence controller was designed to control the opening sequence of the mould.The reset spring had also been applied and improved,in addition to being used for resetting the push plate,it was also used for controlling the sequential opening of the mould template.The installation of wear-resistant pads at the top of the reset rod and rubber pads at the bottom are beneficial for improving the mould life.The mould manufactured under this design scheme ensures that the molding accuracy of the plastic parts is MT3 level,and the yield rate is above 95.6%.