薄壳注射成型技术

介绍塑料薄壳注射成型技术的特点,通过与常规注射成型技术的对比,将薄壳注射成型对设备、模具、塑料及成型工艺条件的要求进行了重点阐述,并分析了薄壳注射成型中的常见问题和相应对策。     

薄壳注塑制品多指标工艺参数优化

高压、高速和高料温的成型工艺使得薄壳注射成型过程更易形成缺陷,因此有必要对薄壁技术进行研究并控制其缺陷。本文综合运用人工智能、模糊理论等对薄壳注射成型缺陷进行研究,开发出了参数优化模糊专家系统,给出了知识推理的技术,建立了缺陷及工艺参数的隶属度函数及模糊规则表。采用隶属函数来反映对象特征的模糊性和模糊关系,实现了基于规则的模糊推理,并对缺陷优化模块进行了实例验证。     

薄壳多孔塑料件高光注射成型工艺研究

对手机壳体塑料件进行了常规注射成型CAE研究,分析存在较为严重的表观质量问题。通过采用高光成型技术,以沉降指数、体积收缩率和翘曲变形为质量指标,利用正交试验和多目标综合平衡法分析研究得出该产品的最佳成型工艺参数组合。分析结果表明,高光注射成型技术在改善薄壳多孔塑料件缺陷方面比常规注射成型有着更大的优越性。     

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.     

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。     

纵论注射成型技术

以注射成型技术在橡胶行业的发展现状为依据,从工作原理、生产工艺、产品质量、生产效率等几个方面着手,对模压成型技术和注射成型技术进行了比较,阐述了注射成型技术的优越性。同时,针对推广注射成型技术遇到的困难,提出了注射成型技术在橡胶行业的推广过程中所需要解决的一系列问题。     

塑料成型加工过程的CAE技术

本文从技术及应用角度系统地介绍了塑料注射成型、气体辅助注射成型、反应注射成型、挤出成型、吹塑成型和热成型CAE技术的概况、内涵及发展趋势。     

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.     

精密注射成型新技术

介绍精密注射成型的基本特征，说明精密注射成型需具备的几个必要条件，简要介绍注射压缩成型，高速注射成型，无保注射成型，高模温注射成型，超微小精密注射成型，计算机化的注射成型及几种关键控制的注射成型等几种精密注射成型新技术的原理，优点和应用前景。指出先进的伺服驱动技术和计算机智能控制技术的不断发展将为精密注射成型技术提供更为广阔的发展空间。     

水辅助注射成型技术研究进展

介绍了水辅助注射成型技术的发展、成型原理及成型的方法种类。与气体辅助注射成型技术进行了对比，指出采用水辅助注射成型技术具有冷却效率高、成型周期短、制品壁厚小、能成型直径较大的制品等优点，这些优点可拓宽该技术的应用领域。最后分析了目前制约水辅助注射成型技术广泛应用的原因．     

INCREASING FLOW LENGTH IN THIN WALL INJECTION MOLDING USING A RAPIDLY HEATED MOLD

Injection molded parts are driven down in size and weight especially for portable electronic applications. While gains are achieved via cost reduction and increased portability, thinner parts encounter more difficulty in molding due to the frozen layer problem. To increase moldability in thin wall molding, a rapid thermal response (RTR) mold was investigated. The RTR mold is capable of rapidly raising the surface temperature to the polymer melt temperature prior to the injection stage and then rapidly cooling to the ejection temperature. The resulting filling process is done inside a hot mold cavity and formation of frozen layer is prohibited. Concepts of scalable filling and low-speed filling are discussed in the article to address the benefit of this molding method. Simulation results showed that significant reduction in injection pressure and speed can be achieved in RTR molding. In contrast to the filling behavior in conventional molding, the injection pressure in RTR molding decreases as the injection speed decreases, and therefore, extremely thin parts can be molded at lower injection speeds. Filling lengths of both RTR and conventionally molded polycarbonate samples, with two levels of thickness, under two levels of injection speed were experimentally studied. The experimental results demonstrated the advantage of the new molding method.     

Micro‐injection molding of thermoplastic polymers: Proposal of a constitutive law as function of the aspect ratios

Based on experimental measurements of the in situ conditions within polymer flow during micro‐injection molding, a new geometrical parameter is defined to predict realistic dimensions of micro‐parts (μparts). To this aim, thin‐walled parts of various aspect ratios “length/thickness” (L/h) were first molded, with two different polymers: (i) a polystyrene and (ii) a cyclo‐olefin copolymer. It is shown that pressure drops (ΔP_i), measured between the injection pressure and the various sensors present in the mold, are directly related to the square of the ratio of L/h. This approach has finally been successfully applied to the results of the literature, confirming its relevance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45719.     

Label behavior property attached on microcellular foamed parts

In comparison with the conventional foaming process, microcellular foaming by injection molding has the advantage of forming small bubbles of consistent size. Because of the reduction in the cycle time, the removal of sink marks, scale reliability, and weight lightening, microcellular foaming by injection molding is widely applied to electrical products, such as automotive parts, office automation equipment, and laptops. When microcellular foaming by injection molding is used with a resin such as polycarbonate, acrylonitrile butadiene styrene, or PC/ABS, microbubbles form. This enables the manufacture of cell phones, notebooks, and personal digital assistants (PDAs), which are impossible to produce with the conventional foaming technique because these products require a thin wall. For most thin‐wall products, spray and labeling processes are added. Therefore, research into the spray and labeling characteristics of injected foamed parts should come before applications. In this article, we analyze the swelling phenomenon that results from labeling on microcellular foamed parts. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 289–293, 2005     

Optimization and numerical simulation analysis for molded thin‐walled parts fabricated using wood‐filled polypropylene composites via plastic injection molding

Plastic injection molding is discontinuous and a complicated process involving the interaction of several variables for control the quality of the molded parts. The goal of this research was to investigate the optimal parameter selection, the significant parameters, and the effect of the injection‐molding parameters during the post‐filling stage (packing pressure, packing time, mold temperature, and cooling time) with respect to in‐cavity residual stresses, volumetric shrinkage and warpage properties. The PP + 60 wt% wood material is not suitable for molded thin‐walled parts. In contrast, the PP + 50 wt% material was found to be the preferred type of lignocellulosic polymer composite for molded thin‐walled parts. The results showed the lower residual stresses approximately at 20.10 MPa and have minimum overpacking in the ranges of ?0.709% to ?0.174% with the volumetric shrinkage spread better over the part surface. The research found that the packing pressure and mold temperature are important parameters for the reduction of residual stresses and volumetric shrinkage, while for the reduction of warpage, the important processing parameters are the packing pressure, packing time, and cooling time for molded thin‐walled parts that are fabricated using lignocellulosic polymer composites. POLYM. ENG. SCI., 55:1082–1095, 2015. © 2014 Society of Plastics Engineers     

Experimental Results of Low Thermal Inertia Molding. I. Length of Filling

In injection molding, complete mold cavity filling is a design goal that has to be met 100% every time. Mold cavity filling is a complicated process which depends on many variables such as mold cavity surface temperature, injection pressure, injection speed, melt temperature, flow index of material being molded, etc. The aim of experimental investigation of the low thermal inertia molding (LTIM) [1] process is to demonstrate the feasibility of molding completely filled, thin parts at low injection pressure and injection speed without sacrificing part quality. The evaluation of the new molding concept consists of comparison of a conventionally molded thin rectangular part with an identical part molded by the LTIM process. The length of filling in the conventional cavity and in the LTIM cavity are compared at different injection pressures and injection speeds. The mold design, experimental procedure, and results of the molding are discussed in the following sections.     

微量注塑机的现状与发展趋势

微注射成型技术是微结构零件最主要的成型方式,受到了人们高度重视,微结构零件迅速发展对微量注塑机带来了新的挑战。阐述了微注射成型技术的产生背景,分析了微注射成型技术对注射设备的特殊要求,从微量注塑机的螺杆式、柱塞式和螺杆柱塞混合式塑化与注射单元机构和液压、电动和电液复合驱动方式等方面介绍了当前微量注塑机的发展现状并比较了它们的优缺点,分析了微量注塑机面临的挑战并展望了微量注塑机的发展趋势。     

Injection molding and injection compression molding of thin‐walled light‐guided plates with V‐grooved microfeatures

In this study, we investigated the feasibility of injection molding (IM) and injection compression molding (ICM) for fabricating 3.5‐in. light‐guided plates (LGPs). The LGP was 0.4 mm thick with v‐grooved microfeatures (10 μm wide and 5 μm deep). A mold was designed to fabricate LGPs by IM and ICM. Micromachining was used to make the mold insert. The Taguchi method and parametric analysis were applied to examine the effects of the process parameters on the molding quality. The following parameters were considered: barrel temperature, mold temperature, packing pressure, and packing time. Mold temperature in this investigation was in the conventional range. Increasing the barrel temperature and mold temperature generally improved the polymer melt fill in the cavities with microdimensions. The experimental results for the replication of microfeatures by IM and ICM are presented and compared. The height of the v‐grooved microfeatures replicated by ICM was more accurate than those replicated by IM. Additionally, the flatness of the fabricated LGPs showed that ICM was better than IM for thin‐walled molding. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

精密注塑成型技术的最新进展

精密注塑成型一般是指成型制件的精度和表面质量均要求很高的工艺,它对注塑机、注塑模、成型工艺、成型物料等均有特殊的要求。分别从精密注塑机、精密注塑模具、精密注塑工艺及材料(制品)性能研究等方面介绍了当今世界上精密注塑技术的最新进展,指出基于计算机模拟与仿真设计的精密注塑成型技术将向着更加高速、超精密、微型化及智能化方向发展。     

试论注射模塑件溢边的形成

从注塑设备、模具设计与制造、塑料选材、注塑工艺参数的调节及塑料件的工艺性等方面讨论了造成注射模塑件产生溢边的原因，有助于对症解决溢边问题。