【作者】 焦志伟；

【导师】 杨卫民；

【作者基本信息】 北京化工大学 ， 机械设计及理论， 2012， 博士

【摘要】 塑料注射成型装备是保证成型制品精密程度的关键因素。根据对精密注射成型原理的分析和合模机构对精密注射成型制品质量的影响研究，以及对现有合模技术的总结归纳，以专利“内动直锁双模板式合模机构”为指导思想，本课题创新研发了一种快速响应的开关阀式的内循环锁模油缸结构及其液控系统，成功制得一种新型内循环二板式注塑机。该新型注塑机的特殊之处在于合模机构，主要由两块模板、两个移模油缸、四条拉杆、四个创新设计的内循环锁模油缸、一套调模机构和一套顶出机构组成，核心特点为四缸直锁、二板调模和液压油内循环。拉杆与锁模油缸活塞杆合二为一，移模油缸与锁模油缸的缸筒分别与定模板连接，活塞杆分别与动模板连接；调模机构和顶出机构安装在动模板上。移模油缸驱动动模板移动时，锁模油缸的内循环功能开启，使其左右腔连通，由此实现移模过程锁模油缸内液压油的内部循环和置换，从而达到节能的目的；移模到达设定位置时，锁模油缸的内循环功能关闭，从而可以进行增压锁模动作。新型四缸直锁内循环二板式合模机构在秉承传统二板式合模机构性能优势的同时，解决了它能耗大、结构复杂等问题。以新型注塑机的产业化为目标，本课题研究了内循环二板式合模机构的系列关键技术，并取得了一些阶段性的研究成果：(1)内循环二板式合模机构理论模型的研究。分别建立了内循环二板式合模机构的锁模刚度模型和移模阶段的能耗模型，探讨了锁模刚度的影响因素和合模机构的节能机理。结果表明，合模机构的结构尺寸、材料和液压油性能等都是影响系统刚度的主要因素；与外循环二板式合模机构相比，内循环二板式合模机构移模阶段无充液能耗，阻力能耗小，由此成就了内循环二板式合模机构优异的节能特性。(2)内循环二板式合模机构液压系统的性能仿真及优化。利用工程分析软件AMESim模拟研究了内循环二板式合模机构液压系统的工作性能，得到了模板运动的位移曲线、锁模油缸压力曲线和泄压阀流量曲线，由此发现了锁模油缸瞬时大流量泄压是造成物理样机CHH200运行不平稳的主要原因。提出了采用节流阀泄压的液压系统改进方案和节流阀通径的确定方法，使液压系统的运行效率和平稳性都得到提高。(3)内循环锁模油缸工作机理的研究。借助计算流体力学软件FLUENT模拟研究了移模过程中锁模油缸的工作过程。研究结果表明，在内循环锁模油缸活塞运动方向前方液压油压力较大，这对移模过程表现为阻力，与能耗模型中的阻力能耗对应，其随活塞运动速度的增加而增大，但即使在最高移模速度时，阻力能耗也很小；在后方压力较低，甚至形成负压；在内循环锁模油缸活塞附近液压油速度场明显，最高速度出现在活塞孔内，活塞后方湍流运动明显，有利于内循环锁模油缸内部液压油与外界的热交换，维持油温恒定。(4)内循环二板式合模机构锁模特性的研究。分别采用模拟与实验的方法研究了内循环二板式合模机构的锁模均匀性和锁模重复性。在研究锁模均匀性时，创新性地提出以模具型腔应变为锁模性能评价指标，区别于现有文献中以模板挠度变形为评价指标，与制品成型密切相关，更能反映精密注射成型的要求。研究结果表明，内循环二板式合模机构的锁模特性优于与三板肘杆式合模机构。(5)精密塑料注射成型标准的研究。根据以上对精密注射成型技术的研究，分析了现行塑料注射成型机标准的现状与局限性，制定了《精密塑料注射成型机》企业标准。该标准对注塑机的性能要求主要分为单项性能要求和综合性能要求，其中综合性能要求为制品重量重复精度，为评价注塑机是否精密的必要条件，本标准规定为1‰。通过以上研究，研制了内循环二板式注塑机的物理样机CHH200和CHH90，根据《精密塑料注射成型机》企业标准和《塑料注射成型机能耗检测和等级评定的规范》对其进行了性能测试。测试结果表明，配备内循环二板式合模机构的注塑机为一级节能精密注塑机。在此基础上，总结得到四缸直锁内循环二板式合模机构的性能特点—节能、节材、高精密、高效率和高性价比，并对性能特点作了分析。通过以上研究工作的开展，内循环二板式合模机构系列技术已相对完善和成熟，目前正被宁波海天集团、宁波海达塑料机械有限公司和浙江申达机器制造股份有限公司实现工业化生产。更多还原

【Abstract】 Plastic injection molding machine (IMM) is the key factor that ensuresthe precision of the molded part. According to the analysis of precisioninjection molding principle, the influences of clamping unit’s performance onproduct quality, and the summaries of the existing clamping technologies, anew kind of internal circulation mold-clamping cylinder and its hydrauliccontrol system were developed based on the patent “internal circulationtwo-platen clamping unit”. A novel internal circulation two-platen IMM,especially a clamping unit with the new cylinder was manufactured. Theclamping unit is mainly composed of a stationary platen, a moving platen, twomold-moving cylinders, four tie bars, four patented mold-clamping cylinders,a mold-adjustment device and an ejector. The rod of the mold-clampingcylinder was integrated with the tie bar of the clamping unit, simplifying thestructure of the clamping unit. The cylinder tubes of the mold-movingcylinders and the mold-clamping cylinders are fixed in the stationary platen,and the rods of them are connected with the moving platen. Themold-adjustment device and the ejector are mounted on the moving platen.When mold-moving, the internal circulation function of the mold-clampingcylinders becomes effective and thus the two cavities are connected, achievingthe internal flow of the oil. The internal circulation of the hydraulic oil in themold-clamping makes machine energy-saving during the mold-moving phase.At the moment of mold-clamping, the internal circulation function is switchedoff and the inlet of the mold-clamping is pressed, building up the clampingforce. On the basis of the advantages of the conventional clamping units, thenovel clamping unit further overcomes the shortcomings of the conventionalclamping units, such as high energy consumption and complex structure. Thecharacteristics of the internal circulation two-platen clamping unit can besummarized as “direct clamping by four cylinders”,“two-platen withmold-adjustment function” and “internal circulation”. Five aspects of workwere conducted around the novel internal circulation two-platen clamping unit,and some research conclusions were obtained as follows:(1) Research of the theoretical model for the internal circulationtwo-platen unit. The clamping stiffness model and energy-consumption modelduring the mold-moving phase were established repectly, and the main factors affecting the stiffness model and the energy-saving principles of the clampingunit were investigated. Results show that the structure size, material of theclamping unit, and oil property are all the main factors of influencing systemstiffness. Comparing with the external circulation clamping unit, the novelclamping unit is energy-saving by eliminating the oil-filling energyconsumption and lowering the resistance energy consumption because of theuse of the internal circulation cylinder.(2) Simulation and optimization on the hydraulic system of the internalcirculation two-platen clamping unit. The working performance of thehydraulic system was investigated through the software AMESim.Displacement curve of the moving platen, pressure curve in themold-clamping cylinder and flow curve in the cartridge valve for releasingpressure were gained. It was found that the large flow in the cartridge forreleasing pressure was the main cause of the prototype CHH200’s poorstability. An optimization scheme was proposed. The determining principle ofkey parameters in the optimization scheme was demonstrated. Theoptimization scheme can improve the operating efficiency and the stability ofthe hydraulic system.(3) Research on the working principles of the internal circulationclamping cylinder. The working conditions of the internal circulation clampingcylinder during the mold-moving phase was investigated by the softwareFLUENT. Results show that the pressure is relatively high at the front of thepiston of the mold-clamping cylinder and it is negative at the back of thepiston. The high pressure displayed as the resistance of the mold-moving,corresponding with the resistance energy consumption in the energyconsumption model. The resistance increases with the increasing of themold-moving speed. The velocity field nearby the piston in the mold-clampingcylinder is intensive. The maximum velocity occurred in the holes of thepiston and the flow behind the piston is turbulent. The turbulent flow is goodfor the heat exchange of the mold-clamping cylinder.(4) Research on the clamping property of the internal circulationtwo-platen clamping unit. The clamping property was investigated from twoaspects: clamping uniformity and clamping repeatability. The former wasinvestigated by simulation method and the latter by experiment method. Whenclamping uniformity was investigated, the mold cavity strain of as theevaluation index of clamping uniformity was proposed innovatively, differentfrom platen strain mentioned in the existing literature. The research resultsshow that the clamping property of the internal circulation two-platenclamping unit is higher than that of the toggled three-platen.(5) Research of the precision IMM standard. Based on the aboveresearches of precision injection molding and the status of existed plasticsIMM standards, the corporate standard “Precision Plastic Injection MoldingMachine” was developed. The standard not only proposes higher technical requirements for IMM, but also provides performance requirements. Theperformance requirement includes individual indicators and comprehensiveindicator. The comprehensive indicator is the weight repeatability and it is1‰according to this standard. The comprehensive indicator is the key index thatdetermines whether an IMM is precise or not.Based on the above researches, the prototype of the internal circulationtwo-platen IMM CHH200was developed and CHH90was manufactured inseries. The performances of the internal circulation two-platen IMMs weretested according to the standard “Precision Plastic Injection MoldingMachine” and “Plastic IMM Energy Consumption Testing and RatingStandard of China”. The test results show that the IMM with the internalcirculation two-platen clamping unit is precise and is of the highest rank interms of energy-saving. The characteristics of the internal circulationtwo-platen clamping unit could be summarized in the following: materialsaving, energy saving, high molding precision, high production efficiency andhigh performance-cost ratio.The above researches make the internal circulation two-platen clampingtechnology relatively perfect and mature. The new technology is beingindustrialized by Ningbo Haitian Group, Ningbo Haida Plastic Machinery Co.,Ltd. and Zhejiang Sound Machinery Manufacture Co., Ltd.更多还原