冷／热模注塑成型技术

在注塑生产中,优化控制模具温度对于获得高表面质量的产品起着重要的作用。本文介绍的“冷/热模注塑”技术即是一种可优化控制模温的新型工艺,它有利于降低制品的内应力,减少甚至消除制品的表面缺陷。     

注塑模具CAD技术的基础研究

对注塑模具计算机辅助设计/计算机辅助制造的开发与应用项目进行前期基础研究,引入了"并行工程"的概念,在综合考虑模具设计过程中的各种费用基础上提出了确定最经济型腔目标函数方法,为后续应用研究打下基础.     

注塑模具的热流道技术

1引言热流道模具与普通流道模具相比,具有注塑效率高、成型塑件质量好和节约原料等优点,随着塑料工业的发展,热流道技术正不断地发展完善,其应用范围也越来越广泛。     

快速热循环工艺对玻纤增强注塑制品表面质量的影响研究

提出将快速热循环方法辅助注塑成型工艺,探究不同型腔温度对薄壁玻纤增强制品的表面质量的改善情况。结果表明:制品表面光泽度随着型腔温度的升高也有所提高,表面的"浮纤"缺陷得到明显的改善,但是制品表面粗糙度则随着型腔温度的升高而增大。通过提高型腔表面质量的同时辅助快速热循环工艺,可以明显改善制品的表面质量。     

快速热循环注塑技术的研究现状与前景

对快速热循环注塑技术的工艺原理、主要特点等方面进行了系统分析;总结了目前国内在快速热循环注塑技术方面的研究现状;最后对快速热循环注塑技术的发展前景进行了预测。     

我国注塑模具CAD／CAE／CAM技术的研究与应用

文章介绍了近几年来国内注塑模具CAD/CAE/CAM技术研究已取得的成果,评价了国内自行开发的注塑模具CAD/CAE/CAM水平与各个方面的研究进展以及在引进工作中存在的问题,提出了注塑模具CAD/CAE/CAM技术研究与应用的方向及开发战略。     

验收注塑模具时需注意的要点

如果某一套注塑模具在A注塑加工厂情况良好,运转正常。而一旦装运到B注塑加工厂后,这套模具即出现问题,需要维修后才能用于加工塑料部件,从而造成B厂的注塑机停工,甚至装配流水线全面停产,需等待模具修复后才可恢复生产。怎样才能避免出现这种状况呢?阅读本文,或许会使从事注塑加工业务的厂家有所启发。     

注塑模具CAE软件系统

本文介绍了注塑模具ＣＡＥ软件，论述了用计算机优化制造工艺和模具设计参数的方法     

汽车塑料制品用注塑模具的CAD／CAM／CAE

本文介绍汽车塑料制品用注塑模具的ＣＡＤ／ＣＡＭ／ＣＡＥ技术。     

注塑模具制造新技术及新趋势

为了能够为注塑加工商生产出可节约投资成本和时间成本，以及提高注塑生产效率的摸具，模具制造商们不断使用新材料和新技术，而这些新材料和新技术则在一定程度上代表了注塑摸具制造的新趋势。[编者按]     

Optimal thermal design of injection molds for filled thermosets

Since the cure rate of injection molded thermosets is usually very sensitive to cavity surface temperature, spatial variations in these temperatures can lengthen the necessary cure time for the entire part and cause distortion and residual stress in the molded article. This problem is addressed in the present paper by combining an optimization algorithm with a quasi-steady heat conduction analysis in the mold to determine the heating line positions and operating temperatures that minimize the spatial variation in cavity surface temperature. The method is applied to an example mold for a flat panel of uniform thickness, using two different gate locations. At a one-minute cycle, the optimal designs for each gate location dramatically reduce the variation in cavity surface temperature compared with corresponding results using a conventional heating system. These results are made more significant by the fact that the optimal designs use considerably fewer heating lines. In spite of their simplicity, the optimal designs still have enough flexibility to adjust to a changing cycle without sacrificing uniformity in cavity surface temperature.     

Thermometry of the working surface of glass molds

Translated from Steklo i Keramika, No. 1, p. 9, January, 1988.     

Optimal thermal design of compression molds for chopped-fiber composites

Because heat is convected by the motion of material in the cavity of a compression mold, the time-averaged heating load on the cavity surface is nonuniform. In rapid production of large, thin parts, this can lead to large variations in cavity surface temperature when the mold is heated by the usual uniform distribution of heating lines. In this paper, a new method is developed for optimizing the mold heating design so that this nonuniform heating requirement can be satisfied with a minimum variation in cavity surface temperature. Oil heating is considered specifically, but the method can also be used for stream or electric heat. The optimal position and power supply for each heating line in the mold is determined by combining mathematical programming techniques with an analysis of the steady temperature field in the mold. The nonuniform heating load on the cavity surface is represented by a time-averaged steady heat transfer coefficient calculated from the transient temperature distribution in a polyester sheet molding compound as it fills the mold cavity. The design method is applied to an example mold for a large flat panel. At a one-minute cycle, the optimal heating design dramatically reduces nonuniformity in cavity surface temperature compared with a conventional distribution of heating lines. The optimal design is remarkably simple, uses only conventional equipment, and involves only half the customary number of heating lines. Nevertheless, it still has sufficient flexibility to adjust for changes in cycle time without sacrificing uniformity in cavity surface temperature.     

Thin‐wall injection molding of polypropylene using molds with different laser‐induced periodic surface structures

In injection molding, high pressure is required to completely replicate the mold geometry, due to the viscosity of thermoplastic polymers, the reduced thickness of the cavity, and the low mold temperature. The reduction of the drag required to fill a thin‐wall injection molding cavity can be promoted by inducing the strong slip of the polymer melt over the mold surface, which occurs within the first monolayer of macromolecules adsorbed at the wall. In this work, the effects of different laser‐induced periodic surface structures (LIPSS) topographies on the reduction of the melt flow resistance of polypropylene were characterized. Ultrafast laser processing of the mold surface was used to manufacture nano‐scale ripples with different orientation and morphology. Moreover, the effects of those injection molding parameters that mostly affect the interaction between the mold surface and the molten polymer were evaluated. The effect of LIPSS on the slip of the polymer melt was modeled to understand the effect of the different treatments on the pressure required to fill the thin‐wall cavity. The results show that LIPPS can be used to treat injection mold surfaces to promote the onset of wall slip, thus reducing the injection pressure up to 13%. POLYM. ENG. SCI., 59:1889–1896, 2019. © 2019 Society of Plastics Engineers     

Dynamics of thermal conditions of molds in molding glass articles

It is proposed to introduce the concept of thermal stability in molds in the course of molding glass articles and a formula for calculating the stability coefficient, which will make it possible to model production conditions taking into account variations in the ambient temperature and molding duration. Translated from Steklo i Keramika, No. 5, pp. 6–7, May, 2000.     

Assessment of weld line performance of PP/Talc moldings produced in hot runner injection molds

Weld lines are weak regions in thermoplastic injection moldings caused by low molecular entanglement and unfavorable orientation. Their occurrence may lead to a significantly reduced mechanical performance of the products. Therefore, when weld lines are likely to occur in molded products, they must be taken into account during the mechanical and technological design processes. The weld lines become more critical when particulate fillers are compounded with the polymer. The performance of weld lines in talc‐filled polypropylene box moldings produced with a double‐gated hot runner mold is assessed in this work. The processing conditions were varied in order to cause morphology and tensile‐impact resistance changes. The weld performance at room temperature was assessed in terms of the energy absorbed in the impact tests. It was found that the performance depends on the injection temperature, the injection rate, and the orientation of the talc particles in the weld‐line plane. J. VINYL ADDIT. TECHNOL., 13:159–165, 2007. © 2007 Society of Plastics Engineers