注射机最大注射量的校核

通过对注射机最大注射量标定含义的分析,指出传统校核注射机最大注射量的方法的不足,提出一种较为精确计算注射机最大注射量的方法以供模具设计人员参考。     

液-电混合驱动注射机

如果不从节省能耗的观点出发．宁愿选用液压式注射机．原因在于动态液压油蓄能器对控制注射机的注射速度和质量十分关键，意大利BMB公司设计了新型Elepack系列电动注射机。这些新的系列设备对上述问题采用新的解决方法，其中注射阶段仍用液压系     

K 2004展出的注射机新品(下)

4包装应用的高速注射机 恩格尔公司展出了用于加工生产薄壁包装制件的MacPAC系列新型高速肘杆注射机,该系列设备合模力从138至715吨,其新式注射装置的特点是可在较低熔融温度下获得较小的注射量和熔体高度均化性能。在这次K2004展会上,现场展示了在138吨注射机上2．9秒内采用双型腔模具注塑出人造黄油桶PP制件。     

橡胶注射成型技术及其设备

本文论述了目前橡胶注射机主要装置的结构和性能特点．简要介绍了全电动橡胶注射机、气体辅助液态硅橡胶注射技术和橡胶注射模具冷流道技术的进展。     

3,000克塑料注射成型机设计概论

本文主要阐述了在原有2,000克注射成型机的基础上,在锁模机构不变的情况下,如何增大注射量,设计3,000克塑料注射成型机(以下简称注射机)的主要方法。首先引用了较多的技术资料,经分析、对比与计算,证实了原2,000克注射成型机锁模机构可适用于新的3,000克注射成型机。其次,叙述了原连杆式锁模机构的特性及锁模力的计算与测定。用较多的篇幅着重论述了塑化、注射部分的设计,特别是对螺杆塑化能力、螺杆驱动扭矩的理论与经验计算作了较详细的论述。本文除了对3,000克注射机的设计外,还述及了一般注射机的有关设计方法。     

注射机的注射量如何确定

在塑料行业中，人们对注射机型号的区分，习惯称为多少克或两(盎斯)。但国内外的制造厂家，对注射机型号的表示方法却不统一，有的以锁模吨位表示，有的以容积cm^3表示，有的以实际注射量表示。特分述如下：     

大型注射机

国内生产的大型注射机有天津塑料机械厂生产的7000克注射机及常州塑料机械厂生产的6000克注射机。75年由上海塑料机械厂设计制造了结构先进的32000克注射机,在胜德塑料厂安装,打算生产聚丙烯浴缸等产品。目前最大的塑料注射制品有航空飞机副油箱(长4.3米、重46公斤),船用推进器(22公斤、单叶高度1.67米)。     

橡胶注射成型设备的技术进步及发展动向

一、橡胶注射成型设备的技术进步!"橡胶注射成型设备主机的技术进步橡胶注射成型机的发展,经历了柱塞式注射成型机至螺杆柱塞式注射成型机,再至螺杆往复式注射成型机的过程。柱塞式成型注射机是最简单的一种注射机。它是借助柱塞的压力把预热的胶料压入模腔中,这种结构的注射机压力损失很大（约为#$%）、生产效率低、劳动强度大、产品质量难以保证。为解决这些问题,注射机发展到塑化和注射分两步进行的形式,把压力损失降低至!$%左右,同时引进了螺杆塑化机构,出现了螺杆柱塞式注射成型机和螺杆往复式注射机。螺杆柱塞式注射机是利用螺…     

新型PET瓶坯注射机效率高

加拿大HUSKY公司新近推出注射PET瓶坯的Hy400专用注射机。据称，该注射机采用国际领先的热流遭模具，成型一模96个瓶坯周期不到7．5秒，合格率基本达到100％。     

塑料注射机虚拟仿真系统的动画研究

采用ProE Plastic Advisor软件研究了塑料注射机虚拟仿真系统,对汽车悬架垫片注塑工艺参数的仿真研究得到了不同注射工艺参数的动画。仿真结果表明:汽车悬架垫片的最佳浇口位置位于零件中心。选取最佳浇口位置为注射位置,汽车悬架垫片的总注射时间为1.24 s,最大注射压力为40.32 MPa,最大注射温度和最小注射温度分别为240℃和239.62℃。冷却过程中,注射位置附近的温差最大,高于平均温度2.92℃;距离注射位置最远的位置温差最小,低于平均温度1.67℃。基于注射机虚拟仿真系统,分析了熔体温度和模具温度对塑料注射过程的影响。结果表明,注射压力和注射时间都随着熔体温度的增加而减小,注射时间随着模具温度的增加而增大,而注射压力随着模具温度的增加而减小。     

振动力场下背压对喷嘴内熔体压力的影响

用聚丙烯做原料,通过对空注射实验,测定了在一定振动条件和背压下喷嘴中的熔体压力。结果表明:振动有助于提高喷嘴中熔体的压力,最大提高约50%;与稳态注射相比,振动能减弱塑化过程中熔体的黏度突变带来的影响;在振动频率为10Hz,振幅为0.08mm时,喷嘴内熔体压力达到最大。     

面向家族制模具多异型腔不平衡充填的快速优化设计

由于家族制模具多异型腔结构的不平衡性,极易在注射成型过程中产生局部充填不满、迟滞效应等缺陷,很大程度上制约着制品的品质。在对塑料熔体流动分析的基础上,发现流道截面半径和长度是影响熔体体积流量和压力分布的重要因素。针对指示灯柱产品多异型腔组合结构的注射成型特征,提出将不同型腔间充填末端的最大平均压力差作为不平衡因子,集成一种基于均匀设计多维结构变量的快速优化机制,结合遗传算法全局优化获得指标最优的流道方案。模拟验证结果表明,结构参数改进后的流道系统充填平衡效果明显优于初始结果。     

Process control of injection molding

This paper discusses the most important input parameters affecting the conventional injection-molding process and describes a closed-loop control system for determining the interaction between ten process inputs and three output parameters. The input parameters are: back pressure, holding pressure, injection time, open mold time, shot size, clamping pressure, injection pressure, screw speed, and boost cut-off. The output parameters studied are: part weight, maximum cavity pressure, and maximum mold deflection.     

Numerical Simulation of Shot Peening Process on Equal Channel Angular Pressed Magnesium Alloy

This paper presents the numerical simulation of inducing residual stresses on equal channel angular pressed (ECAP) magnesium alloy by shot peening process. Mg-Al-Mn (AM) series magnesium alloy was ECAP processed up to 4 passes using route B_C. Microstructures were analysed and grain size reduced from 100 µm for the as-received sample to 3 µm for ECAP 4 pass sample. Tensile test was carried out and maximum tensile strength was found in ECAP 2 pass sample and decreased with higher ECAP passes. Grain refinement was characterized by optical microscopy, electron backscatter diffraction analysis (EBSD) and X-ray diffraction (XRD). Material (tensile) behaviour of 2 pass sample was implemented for finite element modelling. A finite element method was used to estimate the intensity of residual stresses developed due to shot peening in ECAP processed AM80 alloy. Simulation was done with different boundary condition such as impact velocity, geometry of shot-peen media, angle of impact and multiple impacts. The results are presented and the relationship between process parameters and the intensity of residual stresses are discussed. Increase in velocity of shot peening media showed an increase in the magnitude of residual stresses. Change in geometry of shot media altered the contact area between target and shot media during impact which influenced the magnitude of residual stresses and coverage area. The magnitude of residual stresses varied with the angle of impact and the multiple repeated impacts showed that the effective depth of residual stresses increased with the number of impacts.     

Some features of the injection molding of short fiber reinforced thermoplastics in center sprue-gated cavities

This paper describes an investigation into the fiber orientation in a number of center sprue fed cavities in short glass fiber filled polypropylene and nylon. The data have been interpreted in terms of a generalized five-layer structure resulting from the frozen skin formation and the high and low shear levels in the flowing melt. The implications for scaling up the mold size are discussed from the results obtained with different shot volumes. The fiber structure was observed to depend on location in the molding, local injection time, and injection rate. In addition the occurrence of fiber-free layers within the moldings using the filled polypropylene increases with an increase in shot volume, which produces an inherent ‘scale-up’ problem. Notwithstanding the mold geometry subtleties, the fiber orientation in all the moldings follows similar patterns and trends.     

结构件涂装中的屏蔽措施

介绍了结构件涂装过程中的屏蔽措施:孔的抛丸使用锥形橡胶棒进行屏蔽,而喷漆过程可用废旧报纸进行屏蔽;带有螺纹孔或通孔的精加工平面抛丸时,可用钢板进行屏蔽;平面上喷漆屏蔽一般采用胶带和报纸;对于形状规则的平面,喷漆时采用磁性橡胶板屏蔽,效率更高;而磁性橡胶板具有磁性、弹性、电绝缘性以及密度小的特性,更适于钢铁零件抛丸过程的屏蔽。     

Adaptive online quality control for injection‐molding by monitoring and controlling mold separation

This paper presents a unique method that makes use of a small signal (of the magnitude of microns) measured by a precision linear displacement transducer mounted on the outside of mold plates to monitor the momentary separation of the core and cavity plates. The maximum value of the separation is found to be highly correlated with part weight, one of the important quality indices. The whole profile of the mold separation (MS) is monitored and used in order to control the process adaptively and to keep the part quality consistent. Adaptive algorithms are developed to control the switchover point from filling to packing in terms of hydraulic pressure from shot to shot. Within a shot, the hydraulic pressure during the holding stage is manipulated to control the MS profile. The experimental results with different resins and mold geometries show that the variation of part weight is reduced significantly as compared to the conventional hydraulic pressure control. POLYM. ENG. SCI. 46:569–580, 2006. © 2006 Society of Plastics Engineers     

Cyclic Cluster Study on the Bulk Modulus and Hydration Pressure of Magnesia Expansion

Cyclic cluster studies with the quantum chemical method MSINDO were performed to elucidate the key properties of brucite concerning the magnesia expansion. A model is presented that allows the calculation of the compressibility of brucite under hydrostatic pressure. In this way, the bulk modulus of brucite can be determined via the binding energy. The elastic constants, Poisson's ratios, volume compressibility, and finally the bulk modulus were calculated and compared with the experimental values. Except for the component K _a of the compressibility, there is good agreement with the experimental values. Based on the bulk modulus, an expression for the volume change of brucite under pressure is derived. The hydration pressure of the periclase reaction with water to form brucite is related to the partial water vapor pressure. In this way, the maximum hydration pressure was determined.     

高强钢板抛丸清理用金属磨料对比分析

针对泵送结构件用的高强钢板,选择0.6 mm钢丝切丸、0.6 mm高碳铸钢丸、0.6 mm铸钢丸、0.8 mm铸钢丸4种磨料,通过欧文试验比较了这4种磨料的欧文使用寿命、清理效率和处理后工件表面粗糙度。结果表明:0.6 mm钢丝切丸的欧文使用寿命最长,可达到4 135次,清理效率最高,处理后表面粗糙度最小;高碳铸钢丸的欧文使用寿命较钢丝切丸短,但比其他2种铸钢丸欧文使用寿命都要长;0.6 mm铸钢丸处理后的钢板粗糙度在55μm左右,0.8 mm铸钢丸抛打后的钢板表面粗糙度大于63μm。     

球扁药应用于大口径火炮高装填密度发射装药

研究了大弧厚球扁药成型工艺及其在大口径火炮高装填密度装药中的应用可行性。版面上装填试验表明：采用大弧厚球扁药能有效提高装填密度。经钝感处理后,对该药形进行30mm航炮射击试验,当球扁药在装药中的装填比例提高到一定程度时,与制式装药相比,初速增加了2．1％,而最大膛压基本保持不变,点火安全。100H射击试验表明：该药形经钝感处理后,应用于大口径火炮高装填密度是可行的、有效的。