Water-Assisted Injection Molding System Based on Water Hydraulic Proportional Control Technique

Water-assisted injection molding（WAIM）, an innovative process to mold plastic parts with hollow sections, is characterized with intermittent, periodic process and large pressure and flow rate variation. Energy savings and injection pressure control can not be .attained based on conventional valve control system. Moreover, the injection water can not be supplied directly by water hydraulic proportional control system. Poor efficiency and control performance are presented by current trial systems, which pressurize injection water by compressed air. In this paper, a novel water hydraulic system is developed applying an accumulator for energy saving. And a new differential pressure control method is proposed by using pressure cylinder and water hydraulic proportional pressure relief valve for back pressure control. Aiming at design of linear controller for injection water pressure regulation, a linear load model is approximately built through computational fluid dynamics（CFD） simulation on two-phase flow cavity filling process with variable temperature and viscosity, and a linear model of pressure control system is built with the load model and linearization of water hydraulic components. According to the simulation, model based feedback is brought forward to compensate the pressure decrease during accumulator discharge and eliminate the derivative element of the system. Meanwhile, the steady-state error can be reduced and the capacity of resisting disturbance can be enhanced, by closed-loop control of load pressure with integral compensation. Through the developed experimental system in the State Key Lab of Fluid Power Transmission and Control, Zhejiang University, China, the static characteristic of the water hydraulic proportional relief valve was tested and output pressure control of the system in Acrylonitrile Butadiene Styrene（ABS） parts molding experiments was also studied. The experiment results show that the dead band and hysteresis of the water hydraulic proportional pressure relief valve are large, but the control precision and linearity can be improved with feed-forward compensation. With the experimental results of injection water pressure control, the applicability of this WAIM system and the effect of its linear controller are verified. The novel proposed process of WAIM pressure control and study on characteristics of control system contribute to the application of water hydraulic proportional control and WAIM technology.

Simulation and Experiment Research on the Proportional Pressure Control of Water-assisted Injection Molding

Water-assisted injection molding（WAIM）,a newly developed fluid-assisted injection molding technology has drawn more and more attentions for the energy saving,short cooling circle time and high quality of products.Existing research for the process of WAIM has shown that the pressure control of the injecting water is mostly important for the WAIM.However,the proportional pressure control for the WAIM system is quite complex due to the existence of nonlinearities in the water hydraulic system.In order to achieve better pressure control performance of the injecting water to meet the requirements of the WAIM,the proportional pressure control of the WAIM system is investigated both numerically and experimentally.A newly designed water hydraulic system for WAIM is first modeled in AMEsim environment,the load characteristics and the nonlinearities of water hydraulic system are both considered,then the main factors affecting the injecting pressure and load flow rate are extensively studied.Meanwhile,an open-loop model-based compensation control strategy is employed to regulate the water injection pressure and a feedback proportional integrator controller is further adopted to achieve better control performance.In order to verify the AMEsim simulation results WAIM experiment for particular Acrylonitrile Butadiene Styrene（ABS） parts is implemented and the measured experimental data including injecting pressure and flow rate results are compared with the simulation.The good coincidence between experiment and simulation shows that the AMEsim model is accurate,and the tracking performance of the load pressure indicates that the proposed control strategy is effective for the proportional pressure control of the nonlinear WAIM system.The proposed proportional pressure control strategy and the conclusions drawn from simulation and experiment contribute to the application of water hydraulic proportional control and WAIM technology.

自动化快速接头体PA66成型CAE分析及带螺纹机构注射模设计

介绍了自动化设备中采用的快速接头接头体塑件的注塑模具结构设计案例。模具设计中,利用计算机辅助分析得到塑件注塑成型工艺,材料采用30%玻璃纤维改性聚酰胺纤维PA66,模腔单腔采用冷流道侧浇口进行浇注,工艺参数为模具温度85.56℃、熔体温度296.1℃、压力33.77 MPa、保压27 MPa-6 s、成型总周期为27.405 s。模具结构为1模4腔布局两板式模具,模具中设计了一种内壁脱模复合机构,解决了塑件内壁ϕ14 mm空心管道的抽芯脱模及内螺纹的旋转脱模问题,复合机构由液压马达驱动,同步驱动螺纹套管及内螺纹套管型芯2个并列成型零件进行转动,使二者在螺纹导环的导向驱动下,同步完成塑件内壁内螺纹特征的旋转抽芯及内壁ϕ14 mm空心管道上2个型芯的移动抽芯动作。生产塑件关键尺寸的总变形量满足MT4级要求。

塑料制品挤-注-压加工成型工艺的介绍(一)

本文介绍了塑料制品的一种新的加工成型工艺,暂定名为挤-注-压加工成型工艺。

除湿干燥技术在注塑行业中的应用

在注塑成型加工中,对原材料进行干燥除湿处理,既可以防止成品发生银丝、气泡、模糊、透气性不良等现象,又具有降低炮筒温度,缩短成型周期的效果,是注塑成型工艺中必不可少的控制环节。对目前注塑行业已有的除湿干燥技术进行了分析,并提出了除湿干燥技术在该行业中的研究重点及发展方向。

微注射成型工艺及装备研究进展

阐述了微注射成型技术的研究进展,比较了微注射成型技术与传统注射成型技术的不同要求,重点分析了微注射成型工艺及其装备的主要特点及研究现状,并基于熔体微分原理,提出了具有自主知识产权的微分注射成型技术及装备。发现采用微分注射成型创新技术,可以用1台微分注射成型装备达到多台微型注塑机的效果,最终实现微塑料制品高效率、低成本、大批量的生产。

金属粉末注射成形生产设备现状及其发展趋势

根据金属粉末注射成形技术的特点 ,介绍了金属粉末的混炼、注射、脱粘、烧结以及成品后处理各工序所使用的生产设备的原理及其应用现状。阐述了金属粉末注射成形技术工业生产设备的最新发展动态 。

新型注射成型技术——水辅助注射成型

水辅助注射成型技术是一种新型的流体辅助注射成型技术。介绍了水辅注射成型原理、成型工艺过程、工艺特点,论述了水辅助注射成型设备的系统组成、成型设备以及该技术的应用和国内外的研究现状。

水辅注射成型技术的特点及研究进展

介绍了水辅注射成型技术的起源、发展历程、基本原理、所需设备、工艺方法,并且把水辅注射成型技术与气辅注射成型技术进行了比较,总结出水辅注射成型技术方法的优缺点。最后介绍了水辅注射成型技术的研究概况,指出了水辅注射成型技术亟待解决的问题。

粉末注射成形新型快速脱脂工艺——催化脱脂

粉末注射成形工艺包括四个阶段:混炼、成形、脱脂和烧结,其中脱脂是粉末注射成形工艺中最复杂、最重要的环节。本文论述了一种粉末注射成形新型快速脱脂工艺——催化脱脂,详细介绍了催化脱脂原理、脱脂特性及脱脂设备,评述了催化脱脂技术发展现状,并对催化脱脂技术发展作出展望。

气辅成型注气压力的PID控制应用研究

建立了注气压力曲线的控制模型 ,对注气压力曲线的 PID控制算法进行了研究 ,提出了提高注气压力控制精度的扩充临界比例带法的 PID参数计算公式 ,并在研制的小型气辅装置上进行了实验验证。结果表明 :扩充临界比例带法是一种基于系统临界振荡参数的闭环整定法 ,可以优化参数 。

水辅助注射成型技术研究

基于简化和假设,建立了水辅助注射成型数学模型;介绍了水辅助注射成型设备和实验装置,并探讨了水辅材料;对成型过程中的数值模拟及实验研究进行了综述,归纳总结出当前国内外水辅助注射成型研究的重点问题及最新进展。最后,对水辅助注射成型的技术难点、不足及研究方向进行了展望。

水辅注射成型技术综论

水辅注射成型是在气体辅助注射成型的基础上发展起来的一种新兴的注射成型工艺,论述了该技术的成型原理、成型特点、成型工艺、成型设备,以及当前该技术在国内外的应用、发展现状,并指出了水辅注射成型技术今后亟待解决的几个关键性问题。

金属粉末注射成形生产设备及其发展趋势

根据金属粉末注射成形技术的特点,介绍了金属粉末混炼、注射、脱脂、烧结、后处理各工序所使用的各生产设备的原理及其应用。阐述了金属粉末注射成形工业生产设备的最新研究动态,提出了其主要发展趋势。

基于物联网的注塑装备行业生产监控智能化管理平台

针对传统注塑装备生产监控管理平台存在的响应时间慢、鲁棒性差的问题,设计了一种新的基于物联网的注塑装备行业生产监控智能化管理平台。该平台采用浏览器/服务器架构模式,将平台框架分为三个层次,实现分布式管理。以传感器和开关显示仪为采集设备,通过物联网与LPC2478型嵌入式微处理芯片相连,进行数据分析,并通过触控面板显示结果与输出指令,实现注塑装备的控制与管理。结果表明:与传统注塑装备生产监控管理平台相比,该智能化管理平台的响应时间快,鲁棒性提高,有效辅助了注塑装备运行,提高了生产质量与效率。

金属注射成形多功能脱脂炉的设计

金属注射成形技术是近年来发展最为迅速的粉末冶金近净成形枝术。脱脂是金属注射成形的重要工艺,包括热脱脂、溶剂脱脂、虹吸脱脂和催化脱脂。本文设计了一种可用于多种脱脂工艺的多功能脱脂炉,包括催化、溶剂、冷凝蒸汽和虹吸脱脂。介绍了该炉的设计原则、结构特点和经济性能。多功能脱脂炉对金属注射成形技术的工业化有重要意义。

第五届亚太橡塑工业展览会和第十六届中国国际塑料橡胶工业展览会专题报道(II)

简要介绍了第五届亚太橡塑工业展览会 (APPlas 2 0 0 2 )和第十六届中国国际塑料橡胶工业展览会 (Chinaplas2 0 0 2 )上展出的新型塑料挤出成型机械、注射成型机、中空成型机和各种辅机等。

精密注射成型技术探讨

对影响精密注射成型的主要因素诸如成型收缩、模具设计、注塑设备以及注塑材料等进行了讨论,总结了精密注射成型中容易出现的问题及其防止措施。

金属注射成型(MIM)综合脱脂炉的结构设计特点

介绍了金属注射成型(M IM)综合脱脂炉的结构设计特点,该设计可同时满足包括溶剂、催化、冷凝蒸汽、虹吸脱脂在内的脱脂工艺要求。

气体辅助注射成型设备的构建

为促进气体辅助注射成型设备的国产化,介绍了在传统注射成型设备基础上构建该设备的关键技术,提出了气体辅助注射成型设备注气系统的组建及对注射机和注射模的要求,突破了传统注射成型的技术限制,可节约大量因引进进口设备所花费的资金。