【作者】 伍志刚；

【导师】 史玉升；

【作者基本信息】 华中科技大学 ， 数字化材料成形， 2007， 硕士

【摘要】 注塑成型是生产塑料制品最有效的方法之一,注塑模冷却系统的设计直接影响着注塑成型效率和最终制品的质量。较传统的注塑模冷却系统,随形冷却系统有冷却效率高、冷却均匀度好等优点。由于缺乏科学的设计理论与方法的指导,当前对随形冷却系统的设计仍然不得不采用传统的设计方法,致使设计效率低下,设计结果无法达到最优化。这已成为推广应用随形冷却技术的瓶颈。本文在对随形冷却注塑模的传热过程进行理论分析和模拟研究的基础上,对该瞬态传热过程建立了详细准确的数学描述。该数学描述不但适用于圆形截面的冷却水道,还适用于椭圆截面、U形截面等非圆截面和一些特殊的冷却结构,具有广泛的适用性。本文研究了基于选择性激光烧结(SLS)技术的注塑模快速制造工艺,通过实验的方法对随形冷却注塑模形坯可加工性问题进行了深入研究,并制定了相应的设计规则。综合传热过程及可加工性问题研究的相关结论,根据注塑模随形冷却系统的特点,开发出了一套随形冷却系统的设计方法和设计规则。该方法基于区域冷却技术,以最佳型腔壁温度和最短冷却时间为目标,实现了设计结果的最优化。通过以香盒零件注塑模为研究对象的模拟及实物研究表明,内置随形冷却水道的注塑模,其生产效率提高了30%,由冷却不均匀引起的翘曲变形仅为普通模具的20%。最后,采用SLS快速制模工艺制作了金属注塑模具,并成功生产出了注塑件。更多还原

【Abstract】 Injection molding is one of the most effictive techniques for plastic production. The design of the cooling system of injection molds directly affects both productivity and the quality of the final part. Compared with conventional drilled cooling channels, conformal cooling channels have demonstrated simultaneous improvements in cooling efficiency and cooling uniformity. However, because there is no methodology for the design of conformal cooling channels, designers have to use convetional methodology to design them. This is the major bottleneck for the application of conformal cooling system.The transient heat-transfer process of the plastic injection molding is reaserched by the means of heat tranfer theory and numerial simulation software. On the base of those conclusions, the heat transfer mathematic model for conformal cooling is built. In this model, the shape factor is used to correct the calculate result. Not only is this heat transfer model suitable for the circule corss-section cooling channels, but also for other section shapes, such as ellipse, U shape etc.The SLS rapid tooling technology is also studied. Green shape of injection mold with internal conformal cooling channels is formed using the composite metal powders developed in this work and optimal forming parameters. After decomposition, vacuum sintering,dropping infiltration of liquid bronze (or infiltration of epoxy and curing) and being simply machined, the mold can be used for plastic injection.Conformal cooling system design methodology and design rules are developed after reaserching the features of the conformal cooling system. Some new concepts are used in this mehodology, such as cell cooling technology, minium cooling time and suitable temperature of cavity walls etc. By the guide of this methodology, designers can design optimal coformal cooling system efficiency. Finally, the injection mold of pomander with the designed optimal conformal cooling channels is fabricated by using the SLS technique. The production efficiency of the injection mold of pomander with conformal cooling channels is improved 30%, and the warpage is only 20% as much as the conventional injection mold.更多还原