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.

Online Monitoring the Products Quality by Measuring Cavity Pressure during Injection Molding

Injection molding is a complicated production technique for the manufacturing of polymer products. During injection molding, it＇s hard to predict molding quality; the injection molding parameters, such as mold temperature, melt temperature, packing pressure and packing time, affect the final properties of product. The cavity pressure is a significant key factor. Residual stress and injection molding weight are significantly affected by the cavity pressure. This study created an approach to predict weight of injection-molded by real-time online cavity pressure monitoring. This study uses a 6-inch with thickness lmm light guide panel and the largest area beneath the pressure curve of time as well as the maximum pressure as its characteristic. The upper and lower limits of the control are set to ＋2 standard deviations, and GUI （Graphical User Interface）-based LabVIEW software is used to perform calculation and analysis of the pressure curve. The results of the experiment show that the online internal cavity pressure monitoring system can effectively monitor the quality of the molded products. In 500 injection molding cycle tests, its error rate was less than 8%, whereas the deviation in mass of the molded products selected through the system＇s filtering process was successfully controlled to be within ±4%.

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.

Injection molding of micro patterned PMMA plate

A plastic plate with surface micro features was injection molded to investigate the effect of pressure rise of melt on the replication of the micro structures. Prism pattern, which is used in many optical applications, was selected as a model pattern. The prism pattern is 50 μm in pitch and 108° in the vertical angle. The overall size of the plate was 335 minx213 mm and the thickness of the plate varied linearly from 2.6 mm to 0.7 ram. The prism pattern was firstly machined on the nickel plated core block using micro diamond tool and this machined pattern core was installed in a mold for injection molding of prism patterned plate. Polymethyl methacrylate （PMMA） was used as a molding material. The pressure and temperature of the melt in the cavity were measured at different positions in the cavity and the replication of the pattern was also measured at the same positions. The results show that the pressure or temperature profile through the process depends on the shape and the size of the plate. The replication is affected by the temperature and pressure profiles at the early stage of filling, which is right after the melt reaches the position to be measured.

Micro powder injection molding——large scale production technology for micro-sized components

Micro powder injection molding (μPIM),a miniaturized variant of powder injection molding,has advantages of shape complexity,applicability to many materials and good mechanical properties. Co-injection molding has been realized between met-als and ceramics on micro components,which become the first breakthrough within the PIM field. Combined with the prominent characteristics of high features/cost ratio,micro powder injection molding becomes a potential technique for large scale production of intricate and three-dimensional micro components or micro-structured components in microsystems technology (MST) field.

The Banded Spherulites of iPP Induced by Pressure Vibration Injection Molding

Isotactic polypropylene（i PP） samples obtained by pressure vibration injection molding（PVIM） and conventional injection molding（CIM） were studied by polarized-light microscopy（PLM）, respectively. It was found that the alternating bright and dark banded spherulites were generated in the transitional region of PVIM parts. It is the first time that the banded spherulites of isotactic polypropylene were observed in polymer processing. What＇s more, the banded spherulites were proved to be constituted of α-form crystal by hot stage polarized-light microscopy（HT-PLM） and wide angle X-ray diffraction（WAXD）. Morphology of the banded spherulites was also studied by scaning electronical microscopy（SEM）.

模内装饰技术在汽车外饰件上的应用

模内装饰技术已经在注射模中得到了很好的应用,而在模内装饰技术上融合电子电路是一项新工艺创新。对模内装饰与模内注射成型应用进行了介绍,以汽车侧门面板外饰件为案例阐述了嵌件加工工艺流程,着重介绍了导电银浆定义与导电银浆怎样做到嵌件上加工过程,及注射工艺情况。导电银浆应用于电子线路,电子线路并在模内装饰技术中应用,为拓展汽车外饰件功能的应用奠定了较好地基础。

轨道减振器双底模注射硫化成型工艺的研究与应用

对轨道减振器双底模注射硫化成型工艺进行研究,并与传统高压模硫化成型工艺进行对比。结果表明:双底模注射成型工艺缩短了硫化时间,实现了轨道减振器的连续化生产,同时提高了型腔内压,促进了金属与橡胶的有效粘接;双底模注射硫化成型轨道减振器疲劳后垂向静刚度和动静刚度比变化率小,垂向静刚度波动范围在10%以内,产品性能更稳定。

非球面光学元件的快速制造技术

为满足光学行业的市场需求,非球面光学元件的快速制造技术是实现低成本、批量化、高精度生产的最佳解决方案之一。本文主要介绍了非球面光学元件的快速制造技术,包括精密光学玻璃模压成型技术和精密光学塑料注射成型技术,并对两种技术与其他非球面光学元件的制造技术进行了对比,阐述了模具材料种类、模具加工方法、成型材料、成型过程等内容。最后总结了近年来非球面光学元件的快速制造技术的发展现状,并对未来发展进行了展望。

低渗透油田高压注水井在线酸化增注技术

为了解决高压欠注水井降压增注中面临的难题,以定边油田低渗透油藏的主力区块为研究对象,研究该区块的高压注水井在线酸化增注技术。利用单步法酸液体系可以抑制二次、三次沉淀物和溶解堵塞物的特性,设计在线单步法酸化智能增注系统,通过“监控表皮系数变化情况”判断“是否对目的层段持续酸化”,确保最佳酸化效果。室内实验和现场试验结果表明:G-智能复合酸对氟化钠和氟硅酸盐产生二次沉淀的抑制性最好,单步法酸液体系选择G-智能复合酸可以更好地抑制酸反应时二次沉淀物的产生;堵塞物在酸液+助渗透剂剂T影响下的溶蚀率在73.9%~79%之间,堵塞物溶蚀率高于仅加入酸液的,单步法酸液体系选择酸液+助渗透剂可提升堵塞物溶蚀率;与只注入助渗透剂T相比,注入G-智能复合酸+助渗透剂T的高压注水井的油压下降1.0~3.4 MPa,日注水量增加6.1~9.8 m 3,该技术优势显著。

瓶盖注塑模具冷却水道冷却效能分析与结构优化

以瓶盖注塑模具为研究对象,设计了4种不同的随形冷却方案,利用COMSOL软件对模具进行热分析,分析不同冷却水道塑件达到脱模温度所需时间、表面温度分布以及冷却水道压力损失,结果表明第四种冷却水道的冷却性能最优.利用Design-Expert 13软件,基于Box-Behnken响应曲面试验设计方法对第四种冷却水道进行结构优化,获得了给定条件下的最优解,使冷却水道达到脱模时间降低1.42%,表面温度标准差降低2.97%,压力损失降低19.86%.本文方案提升了瓶盖模具冷却性能,缩短了产品的生产周期,提高了产品表面质量,为其他注塑模具冷却水道结构优化提供参考.

含气材料的可压缩性在注塑微发泡中的研究与应用

利用改进的常规微发泡注射成型机可对预塑含气聚合物熔体产生高压而实现了注射成型的压力-体积-温度(PVT)的在线测量。通过对聚苯乙烯和聚丙烯的含气或不含气熔体在一定温度下的压力-体积(PV)行为进行研究,发现含气聚合物熔体的可压缩性远大于不含气聚合物熔体。在实际应用中,含气聚合物熔体的较大的可压缩性可用于辅助注射和加快气体融入熔体过程从而提高发泡质量。另一方面,根据含气聚合物熔体的可压缩性大而存在的安全隐患所做的压力释放试验,首次在国内提出了新的含气材料注射成型的安全操作指导。

空调座盖塑件模内装饰成型工艺与模具设计

针对空调座盖采用塑件模内装饰(IMD)方式进行成型的要求,为其设计了一种基于高压成型3D膜片镶件的IMD成型工艺用于该塑件的成型。工艺中,IMD塑件的保护层3D膜片镶件使用0.25 mm聚甲基丙烯酸甲酯(PMMA)薄膜高压压制+真空吸附3D成型,内衬使用聚碳酸酯/丙烯腈-丁二烯-苯乙烯共聚物(PC/ABS)合金注塑成型。所设计的IMD工艺路径包括9道工序。其中3D膜片镶件高压成型模具为一种模具闭合后具备膜片上表面高压压制和下表面真空吸附能力的双作用成型凸模,对应的高压成型工艺参数为:成型压力(35±1)Kg/保压时间(7.0±1)s/模具温度183℃。内衬的注塑成型中,内衬注塑模具为一种两板式单浇口热流道倒装模具,3D膜片镶件在型腔镶件内的定位依靠2个定模限位滑块进行定位,塑件的脱模由倒装模具动模内设置的2个油缸驱动推板及其上的10个斜顶和14根顶针共同顶出来实现。运用CAE软件Moldflow中“重叠注塑”分析序列对内衬的注塑成型进行了内衬/3D膜片镶件之间的重叠注塑成型仿真优化分析,优化结果为:内衬模腔注塑时,热浇口直径取Ø4 mm,模温79℃,熔料温度260℃,注塑压力90 MPa,保压分4段保压,分别为40 MPa-2 s/30 MPa-2 s/15 MPa-2 s/10 MPa-1.5 s。

厚煤层综放面切顶留巷关键参数研究及其工程应用

【目的】解决工作面采用混凝土柔模充填技术沿空留巷后巷道稳定性问题。【方法】采用“柔模充填+聚能爆破预裂技术”。基于工作面顶板覆岩特征,综合运用理论分析和数值模拟的方法,结合现场施工条件,确定了切顶高度20.5 m、切顶角度5°的深孔预裂爆破方案。【结果】研究结果表明,切顶后煤壁内弹塑性交界线内移,内应力场范围增大,高位砌体梁结构作用明显。随切顶高度的增加,充填体支护阻力和围岩变形量先减小后稳定;随切顶角度的增加,充填体支护阻力和围岩变形量不断增大。现场切顶施工后围岩变形量相比不切顶时顶底板移近量减少了56%,两帮移近量减少了72%,减少了后期维护成本,可为同类条件下煤矿切顶留巷提供经验参考。

玻纤质量分数对长玻纤增强聚丙烯水驱动弹头辅助注塑管件的影响

分别以玻纤质量分数10%,20%,30%和40%的长玻纤增强聚丙烯(LGFRPP)材料制取一系列水驱动弹头辅助注塑(W-PAIM)管件。探究了玻纤质量分数对玻纤断裂长度、纤维取向、壁厚以及耐压性的影响。结果表明,随着玻纤质量分数的增加,玻纤断裂长度在较长区间内占比降低;不同玻纤质量分数的W-PAIM制件在壁厚层的取向不同,水道层的玻纤沿流动方向取向较模壁层和中间层更好,当玻纤质量分数为10%与40%时,水道层玻纤取向度最好,玻纤质量分数为20%时,中间层取向最差,玻纤质量分数为30%时,模壁层的玻纤取向较好;随着玻纤质量分数的增加,WPAIM管件壁厚呈先增加后减小再增加的趋势;随着玻纤质量分数的增加,管件的耐压性先增加后减小最后又增加,当玻纤质量分数为20%时,耐压性最好。

注塑工艺参数对聚丙烯透明料雾度影响研究

采用不同注塑成型方式对聚丙烯透明料雾度测试试样进行了制备,针对聚丙烯透明料雾度有影响的关键因素注塑压力、注塑速度、熔体温度、保压压力等进行了实验探究,确定了雾度试样制备最佳工艺参数为:注塑压力55.52MPa、注射速率40 mm/s、熔体温度200℃、模具温度40℃、保压压力48.58MPa。

煤制烯烃聚丙烯产品注塑成型工艺的优化探讨

聚丙烯注塑成型的工艺参数会影响其结晶过程,造成产品力学性能的不同。为获得最适宜的煤制烯烃高熔融指数聚丙烯注塑成型参数,根据国家标准的要求,分别调整注射速度、保压压力、保压时间、冷却时间、模具温度等参数,注塑拉伸样条,并测试其拉伸性能,考察各注塑参数对聚丙烯力学性能的影响。结果表明:在注射速度为18 mm/s、28 mm/s、36 mm/s、18mm/s,注射时间为1.73 s,保压压力为69.3 MPa、69.3 MPa、66.2 MPa、66.2 MPa,保压时间为40 s,冷却时间为18 s,模具温度为40℃时,聚丙烯产品力学性能达到最佳状态。

渤海油田高效投捞无缆分注工艺研究及应用

针对无缆智能注水技术应用于油田开发中,其工艺存在无缆智能工作筒电路可靠性不足、电池寿命短造成无缆注水管柱寿命低的问题,提出了高效投捞无缆分注工艺。研发的井下可投捞无缆分注工作筒将无缆注水工作筒的电子元器件、传感器部件集成在可投捞注水芯子内部,利用钢丝作业实现芯子的快速维修、更换,有效地延长管柱寿命。同时研发了配套的地面发码系统与高效压力波控制编码技术,通过软件和硬件的配合,实现了水嘴开度调节、流量预设等7大功能,有效地提高了无缆调节效率。目前渤海油田现场应用62井次,投捞成功率达到100%,注水合格率达到97%以上。该技术的研发可为海上油田的高效智能注采提供新的选择。

基于三维实体模型的注塑成型保压过程模拟

基于现有的超算平台和有限体积法计算程序,开发基于三维实体模型的注塑成型数值模拟计算模型。基于可压缩两相流模型进行计算,采用有限体积法进行离散,结合流体体积法(VOF)进行界面捕获,使用Cross-WLF黏性模型表征聚合物熔体的流变行为。以平板型腔和带圆柱嵌件型腔熔体保压过程为例进行数值模拟计算,成功预测型腔压力、温度和应力等流动特性的分布,模拟结果与文献中的结果基本吻合。

低渗透性煤层气液两相压注复合增透技术研究及应用

针对骆驼山煤矿低透气性煤层水力压裂后期钻孔瓦斯抽采衰减严重的问题,提出气液两相压注协同增透技术,现场试验表明:气液两相压注增透技术流量平均值是原有水力压裂技术的1.24倍,是单一空气压注钻孔的6.17倍,且流量衰减仅为原有水力压裂技术的64%,是单一空气压注钻孔的45%。对比原有水力压裂技术,气液两相压注增透技术协同增透效果明显,酸化压裂与注气增流相互促进,煤体内裂隙网络的连通性和注气增流作用影响范围都得到进一步的增强,保障矿井安全高效生产。