Vapor sensing properties of thermoplastic polyurethane multifilament covered with carbon nanotube networks

The volatile organic compound (VOC) vapor sensing properties of a novel kind of thermoplastic polyurethane multifilament - carbon nanotubes (TPU-CNTs) composites is studied. And the sensing is based on changes in the electrical resistance of the composites due to vapor contact. The composites were readily obtained by adhering CNTs on the surface layer of TPU by means of simply immersing pure TPU multifilament into CNT dispersion. The uniformly formed nanotube networks on the outer layer of composite multifilament are favorable for providing efficient conductive pathways. The resulting TPU-CNTs composites show good reproducibility and fast response (within seconds) of electrical resistance change in cyclic exposure to diluted VOC and pure dry air. The vapor sensing behaviors of the composites are related to CNT content, vapor concentration, and polar solubility parameters of the target vapors. A relatively low vapor concentration of 0.5% is detectable, and a maximum relative resistance change of 900% is obtained for the composite with 0.8 wt.% CNT loading when sensing 7.0% chloroform. It is proposed that both the disconnection of CNT networks caused by swelling effects of the TPU matrix and the adsorption of VOC molecules on the CNTs are responsible for the vapor sensing behavior of TPU-CNTs composite, while the former effect plays the major role.     

聚合物注射成型保压分析研究进展

本文综述了聚合物注射成型保压分析的理论模型及其描述方程，并对今后的发展方向进行了展望，保压过程是一个非等温过程，熔体具有可压缩性，弹性的影响不应忽略，对于结晶聚合物，应考虑结晶对压力分布和温度分布的影响。     

注塑机动模板拓扑优化

在五点曲肘式注塑机中,动模板是关键的零件之一,它需要将机铰的力分散传递到模板平面,均匀地压紧模具,使熔融塑料能够准确复制型腔的形状.在注塑过程中,型腔的压力可高达200MPa,这对模板的强度刚度提出了严格的要求.若模板刚度不足,则会产生胀模现象,使制品形成飞边或变厚;若强度不足,模板则会爆裂报废.本文引用了一种自组织的方法对动模板进行拓扑优化.拓扑优化在减小模板重量的前提下,优化材料在模板里的分布,使其在负载下应力分布更为均匀,从而材料得到充分利用,在降低重量的同时保证模板的刚度和强度,延长其寿命.本文通过拓扑优化将模板的重量降低到原来的50%,而模板各点刚度下降大约15%。     

液晶及其显示器原理分析

本文简要回顾了液晶的发现过程,介绍了液晶和液晶显示器(LCD)的特性、基本原理和发展方向.     

基于虚拟现实的塑料注塑成型系统场景可视化

虚拟现实,作为一门新型技术,已成功地应用于工程、设计和制造业领域.该文针对塑料注塑成型复杂的设计、制造、加工过程,将虚拟现实技术应用到塑料注塑成型过程中,并利用Delaunay三角剖分技术结合立体显示技术,开发了一种实用的虚拟场景.在此场景中可实现注射系统的全部设计和制造过程,并结合面向对象的编程技术和OpenGL图形库,实现注射成型系统在虚拟现实场景中的动态可视化,从而能够预先感知注射系统在设计、制造过程中可能出现的问题,并加以解决,实践证明了其可行性.     

A CAD-CAE Integrated Injection Molding Design System

. In the injection molding design process, interaction between design and analysis is very intensive. This is to ensure that the plastic part being designed is manufacturable by the injection molding process. However, such interaction is not supported by current computer-aided systems (CAD and CAE), because design and analysis are realized as isolated modules. Although most of CAE systems provide built-in modeling tools, these are only meant for developing an analysis model with very limited CAD functionality. On the other hand, some CAD systems have allowed certain CAE systems to run under their environments, but inherently they use different data models, thus communication between them is poor. This paper presents an innovative, CAD-CAE integrated, injection molding design system. This system uses an integrated data model for both design and analysis. The system is built on top of existing CAD and CAE systems, which not only greatly saves development effort, but also makes full use of the strong functionality of commercial computer aided systems. The system architecture consists of four layers: a CAD and CAE platform layer; a CAD-CAE feature layer; a model layer; and a GUI layer. Two design cases were studied to illustrate the iterative design-analysis process and use of the developed system.     

注塑车间远程集中监管系统

本论文介绍了基于西门子公司S7-200可编程逻辑控制器(PLC)的注塑车间远程集中监管系统的设计.PLC对注塑机生产的过程控制、数据采集、与上位机进行数据交换等功能.本系统利用设计的数据采集、数据压缩、数据传输、数据处理几大功能模块实现对注塑车间的生产过程进行监视和管理.根据注塑车间远程集中监管系统得到的实际生产数据,经过系统分析、比较、判断、总结,最终得出一个真实、可靠的高效生产模式.     

基于嵌入式Linux的注塑机控制系统解决方案

嵌入式Linux操作系统同WinCE、pSOS、PalmOS相比有很多优点,有取代其它嵌入式操作系统的趋势;由于嵌入式Linux的出现使得构造一个大型机器的复杂控制系统变得简单和容易。文章所研究的是结合注塑机的工艺特点,将嵌入式Linux操作系统应用到塑料成型控制系统中的一些关键问题,重点是讨论构造其控制器的软、硬件设计方法。     

Three-dimensional finite element method for the filling simulation of injection molding

With the development of molding techniques, molded parts have more complex and larger geometry with nonuniform thickness. In this case, the velocity and the variation of parameters in the gapwise direction are considerable and cannot be neglected. A three-dimensional (3D) simulation model can predict the filling process more accurately than a 2.5D model based on the Hele–Shaw approximation. This paper gives a mathematical model and numeric method based on 3D model to perform more accurate simulations of a fully flow. The model employs an equal-order velocity–pressure interpolation method. The relation between velocity and pressure is obtained from the discretized momentum equations in order to derive the pressure equation. A 3D control volume scheme is used to track the flow front. During calculating the temperature field, the influence of convection items in three directions is considered. The software based on this 3D model can calculate the pressure field, velocity field and temperature field in filling process. The validity of the model has been tested through the analysis of the flow in cavities.     

虚拟塑料注塑成型教学系统

塑料注射成型技术的发展与注射模具设计人员需求的增长十分迅速,模具设计人员学习必要的塑料成型基本原理是掌握注射模具设计方法的现实需要。该文在虚拟现实（VR）技术的基础上,结合基于三维模型的注塑成型FEA技术、面向对象的编程技术和OpenGL图形库,研究并实现了沉浸式、交互式的虚拟塑料注射成型教学仿真系统（VPIM）,提出了立体成像算法,给出了模拟注射成型过程运动仿真的方法,借助VR外设及通过建立知识化、数字化、可视化、现实化的教学平台来提高设计人员的学习效率、学习兴趣及对问题理解的深入程度。     

有限单元法在塑料注射充模流动模拟中的应用

对塑料熔体注射成型充模流动过程的流变方程进行了熔体充模过程流变方程参数基于3维有限单元法的数值求解研究,得到基于形函数的压力刚度矩阵、温度刚度矩阵的方程式,进而得出压力场、速度场、温度场数值解的方程式。据此完成了注射熔体流动充模过程由M atlab编程实现的有限元分析本体程序。用具体的注射成型塑料制品作为检验实例,用2种不同的塑料进行注射成型模拟,其结果与国际著名的M old flow商品化软件和文献数据进行比较,表明本研究的设计软件算法正确、程序运行速度快。     

神经网络在注塑制品材料选择中的应用

该文分析了注塑成型制品的功能要求与树脂材料性质之间的作用关系，采用模糊手段表示了对材料的选定度，提出了一种基于神经网络的注塑制品的材料选择方法。     

ZrO_2汽车氧传感器烧结工艺研究

采用注射成型方法制备汽车氧传感器。通过分析得知,烧结制品好的力学性能和高导电率往往是矛盾的,要获得四方相ZrO2须保证烧结过程中材料的晶粒尺寸要控制在1μm以内。综合考虑,烧结温度在1550℃左右比较合适。     

Analysis of morphology and performance of PP microstructures manufactured by micro injection molding

In this paper, PP (polypropylene) microstructures were manufactured by micro injection molding (MIM). The surface topography and internal defect under different process conditions were studied. An internal defect named “hollow” was observed in microstructures made without vacuum. To investigate the morphology (crystal and phase), the microstructures samples were cut to slices with 10 μm thickness along the filling direction. Results of polarized light microscopic observation reveal that these microstructures also represent “skin-core” morphology, i.e. a highly oriented non-crystalline skin layer, a shear zone with column crystal essentially parallel to the injection direction and a spherulites core. However the morphology distribution of microstructures is different from the macroscopic structure: the non-crystalline layer is much thinner, the ratio of skin layer (non-crystalline and column crystal layer) to core thickness is very big, there is no change of spherulites dimension from skin to center. So the microstructures must have a special mechanical performance differ from the macroscopic parts.     

注塑机注射速度控制研究现状和发展综述

对近年来注塑机注射速度控制方法进行研究,典型的控制方法可以分为传统控制方法、自适应控制方法、智能控制方法。阐述各种方法的研究现状、应用成果及其优缺点。注射速度是整个注射过程中非常关键的控制变量。最后对注射速度控制的发展做展望。