MEM支撑工艺参数的研究

针对快速成型产品悬空部分的支撑问题,文中根据实际情况设计了实验方案,归纳出了常见零件的4种悬空特征,分别为开放式悬臂、倾斜形、圆孔形和平顶形.采用现有的MEM工艺进行加工实验,得到了在加工工艺过程中不加支撑或尽量减少支撑的条件:开放式悬臂长度L≤6mm、倾斜形特征倾斜角度(0)≥30°、圆孔半径R≤4mm、平顶长度M≤8mm.     

无支撑熔融挤压快速成形的参数研究

针对快速成形产品悬空部分的支撑问题,归纳出常见零件的5种悬空特征,分别为倾斜形、弧顶形、平顶形、开放式悬臂形、封闭式悬臂形。采种熔融挤压工艺进行加工试验,得到这5种悬空特征无需添加支撑即可成形的极限悬空参数,分别为倾斜角60°、弧顶半径4 mm、平顶长度8 mm、开放式悬臂长度3 mm、封闭式悬臂长度5 mm。成形环境温度对悬空部分的成形质量影响较大。     

零件表面倾角对MEM工艺支撑参数的影响

分析了表面倾角和水平悬空长度对熔融挤压MEM快速成型产品的支撑影响,以多种参数进行实际加工,得到无需添加支撑即可成型的极限悬空参数:表面倾角60°,水平悬空长度3mm。零件悬空部分的无支撑成型是利用成型材料自身的粘结性能、强度及刚性来支持丝料的悬空连续轨迹,保证后续成型。成型环境温度对悬空部分的成型质量影响较大。     

熔融挤压快速成形支撑参数的研究

针对快速成形产品悬空部分的支撑问题,归纳出常见零件的5种悬空特征,分别为倾斜形、弧顶形、平顶形、开放式悬臂形、封闭式悬臂形。采种熔融挤压MEM(MeltedExtrusionModeling)工艺进行加工实验,得到这5种悬空特征无需添加支撑即可成形的极限悬空参数,分别为倾斜角60°、弧顶半径4mm、平顶长度8mm、开放式悬臂长度3mm、封闭式悬臂长度5mm。零件悬空部分的无支撑成形是利用成形材料自身的强度和刚性来支持丝料的悬空连续轨迹,保证后续成形。成形环境温度对悬空部分的成形质量影响较大。     

熔融挤压快速成型中支撑工艺的研究

针对单喷头的熔融挤压快速成型制作成型件的特点,必须保证能很好地去除支撑才能得到制件的要求,对熔融挤压快速成型中支撑工艺进行了研究。支撑关系到零件的加工成败、加工时间和表面质量等,提出了支撑的一些生成原则和设置辅助支撑的作用。根据挤出丝的截面形状,建立了支撑丝宽的数学模型,对生成支撑的重要工艺参数进行了分析,结果表明:栅格宽度w较出料速度v对支撑间的间隙L0影响要大,但当层高h由0.2 mm变为0.1 mm时,栅格宽度对支撑间间隙的影响基本不变,而出料速度对支撑间间隙的影响成倍增长,并进行了实验验证。     

SLM快速成型中的支撑结构设计研究

在选择性激光熔融成型中,添加合理的支撑结构对保证具有复杂曲面零件的完整制造有着重要的作用。以最终成型零件的可行性及成型精度为目标,以相关实验验证为依据,对选择性熔融成型中支撑结构设计进行了研究。在STL模型的基础上,针对具有不同复杂曲面的零件,设计了按不同密集度分布的支撑,进行了系统的实验,并对不同参数支撑结构的实验结果进行了分析,得出了支撑密度、支撑当量半径、支撑半径补偿与零件表面倾斜角度间的关系,为选择性激光熔融成型中支撑结构的研究与运用提供理论依据。     

典型大尺寸薄壁快速成型件的加工方法

在快速成型机加工大尺寸、薄壁零件时,快速成型机的激光功率、加工中的零件的受力情况和零件的支撑工艺都会影响到零件最终精度。结合在实际加工原型件中遇到的具体问题,进行了加工工艺方法的研究和解决,以便更有效地缩短产品的研发周期,提高产品质量和缩减产品的成本。     

熔融堆积成型系统中结构自动生成算法的研究

在熔融堆积成型系统中，零件原型的制作是靠热喷头挤出热熔丝逐层堆积成型的，因此，在零件原型的成过程中，支撑结构的生成是不可避免的。通过利用截面轮廓区域的自动识别、多边形区域的布尔运算以及多边形轮廓的OFFSET运算等几种关键算法，提出了SW2501快速成型系统中支撑结构的自动生成算法。该算法实际应用效果较好。     

FDM快速成型机原型精度分析及对策

熔融沉积快速成型（Fused Deposition Modeling,FDM）是快速成型技术中的一种。在FDM工艺成形过程中,原型精度受到众多因素的影响,分析了几个影响成型精度的因素,结合实际加工提出了相应的解决办法,对实际加工生产中的参数选择和结构改进的研究具有一定的参考价值。     

基于熔融挤压工艺的模型质量和强度影响因素的分析

分析了采用熔融挤压快速成型工艺下形成的模型表面质量和强度的影响因素,针对这些因素提出了合适的解决方法,并指出在实际加工时,要根据模型的结构、复杂程度和技术要求找到最佳的加工方案。     

Part Orientation in Stereolithography

Rapid prototyping (RP) machines reduce the lead time and cost of new products by automating the prototype manufacturing phase of the product development process. However, it is necessary for operators to orientate the prototype correctly in the RP machine to obtain the best trade-off between time, cost, and accuracy. The purpose of this work is to produce a decision-support tool to help RP users in this task. The tool is aimed at stereolithography which is the most widely adopted RP technology. The tool is a feature-based system produced using an object-orientated programming language and a solid modelling CAD environment. Cost, time, problematic features, optimally orientated features, overhanging area, and support volume are considered when recommending a build direction to the user. Three sample parts were used to illustrate the performance of the system. The system yielded the best surface finish and correctly highlighted several problem features.     

On-Line Layer Profile Dimensions Measurement of Model Maker Rapid Prototyping Using Vision Technology

The key principle of rapid prototyping (RP) is to fabricate a 3D object, layer by layer, which is a 2D fabrication process. Vision technology is being successfully applied in general industry to inspect object dimensions on-line, but most of the applications are limited to objects with 2D patterns. Hence, it should be possible to apply vision technology to inspect RP layer profile dimensions on-line. A CCD camera was employed to capture the layer profile image of the Model Maker (MM) RP system layer by layer. The captured image was processed to identify the RP profiles and further to calculate the real profile dimensions of the fabricated layer. The experimental results demonstrate that the dimensions of an RP part could be measured in situ, layer by layer, and could, potentially, be real-time monitored. This paper presents the vision calibration and the detailed image processing algorithms for the single layer profile identification and dimensions measurement. The results show that the measurement accuracy of the layer profile was about 98%.     

快速成型技术工艺特点及影响精度的因素

快速成型是一种基于离散堆积成型思想的数字化成形技术,可以在无需任何模具、刀具和工装的情况下,直接从CAD数据,快速制造出具有任意复杂形状的实体部件。介绍了快速成型领域四种典型的成型技术及其加工原理,阐述了其加工过程中所具备的快速性和高度柔性等现代化制造特点。比较了典型快速成型工艺的适用领域、加工成本和技术参数,找出影响成品精度的工艺及设备方面因素。分析各种成型技术在成形精度、表面质量、材料成本等方面的优点和缺点。     

Optimization of stereolithography process parameters for part strength using design of experiments

Rapid prototyping (RP) is an emerging technology that has been implemented in many spheres of industry – particularly in the area of new product development. Growth of this field has been rapid in recent years. Stereolithography (SL) is one of the most popular RP process used for rapid tooling applications. There are several process parameters contributing to the strength of an SL product. The contribution of three parameters; namely, layer thickness, post curing time and orientation are most significant. In light of this concern, an attempt has been made to study and optimize these process parameters for maximum part strength, and develop an empirical relationship between process parameters and part strength through design of experiments (DOE). The proposed DOE is verified with the data of experiments conducted under standard conditions.     

熔融沉积快速成型工艺过程分析及应用

介绍熔融沉积快速成型技术的基本原理,分析成型工艺过程的技术特点。从机械系统和控制系统等主要组成部分论述了熔融沉积成型设备的整体构造。以一个深沟球轴承为研究案例,详细地论述了成型件的具体加工过程并在MEM320A快速成型机上加工出ABS材料的实物。最后,探讨了熔融沉积快速成型技术在产品设计、功能展示、样品制造和生物医学等领域的应用情况,同时展望了该技术在未来的发展前景。     

基于快速原型技术的产品成型研究

从快速原型的原理出发对快速原型技术的数据处理和工艺方法进行了分析和研究,并利用UG软件进行产品设计与开发,同时对产品模型进行功能分析,利用快速原型设备制作出产品的实体模型,在此基础上对产品设计方案进行了修改与设计评价。     

A BOM Oriented Class-Based Storage Assignment in an Automated Storage/Retrieval System

A solid laser-diode plotter (SLP) system is one of the commer-cial rapid prototyping (RP) systems developed and marketed in Japan. In the SLP system, two semiconductor lasers are employed instead of a UV laser or a diode-pumped solid state laser, as used in the stereolithography process to cure a specially designed photopolymer. An ascending platform is used to build the suspended solid model, and only a small amount of resin is cured in a thin layer on a plate of glass just below the last layer built. Hence, the SLP system is a low-cost RP system and is well suited for educational purposes, because a high-power laser is not involved and only a small amount of resin is used. However, the over-curing of the overhanging area is a processing problem in the ascending platform method, because the built part is suspended. In order to reduce the over-curing of the SLP parts, the Taguchi method was employed to analyse the processing parameters. The effect of the processing parameters on the over-curing was investigated and presented. The results show that the over-curing of the SLP parts was reduced about 40% using the optima processing parameters as analysed by the Taguchi method.     

<Emphasis Type="Italic">Rapid Moulding Using Epoxy Tooling Resin</Emphasis>

Rapid prototyping (RP) is fast becoming a standard tool in today’s product design and manufacturing environment. Significant benefits in terms of lead time and cost savings have been reported with the use of RP technology. However, these benefits can be derived only during the design and planning stages of a new product where RP parts are produced in small quantities for design evaluation, form fitting, and marketing analysis. The high cost of raw material stock used in current RP systems makes them economically unsuitable even for small-batch production during the product evaluation and manufacturing stages. Further to this, the difference between the mechanical and physical properties of RP and traditional manufacturing materials limits the functionality of RP end products. Rapid tooling (RT) technology has opened up new cost-effective solutions for small-batch production. In this paper, a technique using a rapid soft-tooling approach, namely, aluminium filled epoxy resin tooling for injection mould preparation is successfully explored. An aluminium filled epoxy resin mould is evaluated and the characteristics of the injection-moulded end products are presented.     

熔融挤压快速成形特殊形状产品的工艺探讨

分析熔融挤压快速成形的工艺,针对三种特殊形状产品,从支撑、台阶效应、丝料特性等几个方面探讨了成形方向选择和壁厚控制对加工质量的影响,并成功加工出结构复杂产品、片状产品和薄壁半透明产品。     

扫描速度对熔融堆积成形影响的有限元分析

熔融堆积成形是一种重要的快速原型工艺，为了提高其加工效率，提出了高速扫描的工艺方案，通过有限元分析及工艺实验，验证了高速扫描的合理性和可行性。数值建模以及有限元分析在非线性有限元软件MRAC的基础上进行，利用了单元激活技术，进行了二次开发，合理地描述出熔融堆积成形过程。