7。 Test of the injection mold

   Tests have been carried out with various representative thermoplastic materials such as PP, PA, HDPE and PC, and it has been analysed the properties of the injected parts such as dimensions, weight, resistance, rigidity and ductility。 Mechanical properties were tested by tensile destructive tests and analysis by photoelasticity。 About 500 injections were carried out on this core, remaining under conditions of withstanding many more。 文献综述

In general terms, important differences were not noticed between the behavior of the specimens obtained in the core and the ones from the machined cavity, for the set of the analysed materials。 However in the analysis by photoelasticiy (Fig。 7) it was noticed a different tensional state between both types of specimens, basically due to differences in the heat transference and rigidity of the respective mold cavities。 This difference explains the ductility variations more outstanding in the partially crystalline materials such as HDPE and PA 6。 

Fig。 7。 Analysis by photoelasticity of injected specimens。

   For the case of HDPE in all the analysed tested tubes it was noticed a lower ductility in the specimens obtained in the nickel core, quantified about 30%。 In the case of PA 6 this value was around 50%。 

8。 Conclusions

   After consecutive tests and in different conditions it has been checked that the nickel sulfamate bath, with the utilized additives has allowed to obtain nickel shells with some mechanical properties acceptable for the required application, injection molds, that is to say, good reproducibility, high level of hardness and good mechanical resistance in terms of the resultant laminar structure。 The mechanical deficiencies of the nickel shell will be partially replaced by the epoxy resin that finishes shaping the core for the injection mold, allowing to inject medium series of plastic parts with acceptable quality levels。 

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关键字：发展   模具

   随着全球经济的发展,新技术不断取得新的进展和突破,技术的飞跃发展已经成为推动世界经济增长的重要因素。市场经济的不断发展,促使工业产品越来越向多品种、高质量、低成本的方向发展,为了保持和增强产品的市场竞争力,产品开发周期、生产周期越来越短,于是使每一种产品基本工艺设备模具要求越来越苛刻。一方面企业追求规模效益,导致模具转向高速、精密、长寿命方向发展,另一方面企业为了满足多品种,产品更新快,赢得了市场的需求,要求模具转向生产周期短,成本低的快速经济发展方向。计算机、激光、电子、新材料、新技术的发展,使快速经济制模技术更加强大,应用范围不断扩大,种类不断增加,创造经济效益和社会效益越来越显著。快速经济制模技术和传统机械加工相比,这种技术能使周期变短,成本降低,精度和寿命可以满足生产操作要求,是综合的一种经济效益非常显著的模具技术,总结起来,有以下几个类型。来;自]优Y尔E论L文W网www.youerw.com +QQ752018766-

1、快速原型制造技术

   快速原型制造技术也被叫做RPM,是80年代后期发展的一种新的制造技术。美国、日本、英国、以色列、德国、中国都推出了自己的商业化产品,并逐步形成了新的产业。RPM是计算机、激光、光学扫描、先进的新材料,计算机辅助设计(CAD),计算机辅助处理(CAM),数控(CNC)综合应用的高新技术。成形概念以平面离散,堆积为指导,控制以计算机和数字控制为基础,以最大的灵活性为总体目标。它抛弃了传统的机械加工方法,对制造产业转型是一个重大突破,使用RPM技术有可能直接或间接快速制模,这种技术已被行业广泛应用汽车、航空、电器、船舶、医疗服务、模具。