UV-LIGA和微细电火花加工技术组合制作三维金属微结构的研究

研究了UV-LIGA和微细电火花加工技术组合制作三维金属微结构的工艺方法。首先通过UV-LIGA制作二维金属微结构,再对该微结构进行微细电火花加工得到三维金属微结构。该方法具有加工精度高、可实现自由曲面三维金属微结构制作的优点。制作出了局部为梯形凸台和锥形凹槽三维微结构的镍模具。分析了微细电火花加工中放电参数对表面粗糙度的影响,通过减小放电电压和电容的方法降低了表面粗糙度。     

微细电极在线制备技术的研究进展

介绍了反拷块法、WEDG法、电化学腐蚀法、EEDG法等几种微细电极的在线制备方法、基本原理、研究现状及最新进展,为实际加工轴类工件及制备工具电极等提供了有益参考.     

Process planning and electrode wear compensation for 3D micro-EDM

This paper presents a novel multi-cut process planning method and a new electrode wear compensation method based on a machine vision system for three-dimensional (3D) micro-electrical discharge machining (micro-EDM). Front wear and corner wear of tool electrode can be measured and compensated in a direct manner by the vision system??s image processing software capabilities. Experiments have shown that corner wear ratio (defined as a ratio between the length of corner wear and electrode diameter) is linearly proportional to machining length under a fixed machining depth condition. Track overlapping between the two adjoining paths is designed appropriately according to the corner wear ratio. Experimental results not only indicate that the proposed multi-cut process planning and electrode wear compensation methods can significantly improve machining accuracy and reduce machining time for the micro-EDM process, they also demonstrate that the X?CY dimensional errors of micro-structures can be controlled within 10???m.     

An optimisation of micro-EDM operation for fabrication of micro-hole

Micro electro-discharge machining (micro-EDM) operation is a versatile operation to machine any hard conducting material to fabricate micro-products of different shape and size. The micro-holes are a common feature in many micro-products. It is a challenging task to improve the surface integrity and aspect ratio of holes. A number of controlling parameters affect the micro-EDM operation. In the present investigation, the optimization of micro-EDM operation has been carried out for fabrication of micro-holes using design of experiment technique using the Taguchi method. The circularity error, the recast layer and machining time has been analysed. The significant factors influencing the process have been found out. The workpiece is taken as copper and the tool is tungsten electrode.     

UV-LIGA和微细电火花加工技术组合制作三维金属微结构

为了制作三维金属微结构,研究了UV-LIGA和微细电火花加工技术组合的工艺方法。使用UV-LIGA技术制作了准三维金属微结构,然后,对该微结构进行微细电火花加工制作三维金属微结构。使用提出的方法制作出了局部为梯形凸台和锥形凹槽三维微结构的镍模具,给出了梯形凸台和锥形凹槽的尺寸。分析了微细电火花加工中放电参数对表面粗糙度的影响,在工作电压为65V,标称电容为100pF时得到了Ra为0.08μm的微细电火花加工表面。研究结果表明,使用该方法可实现三维金属微结构的制作;通过减小工作电压和标称电容的方法可降低微细电火花加工的表面粗糙度。     

光学三维测量技术与应用

光学三维测量技术是一种可视化的测量技术,能完成复杂形体的点、面、形的三维测量,能实现非接触测量,在制造业和航空航天领域得到广泛应用。航空三维激光扫描与摄影测量技术利用激光测距原理和航空摄影测量原理,与基于全球定位系统(GPS)和惯性测量装置(IMU)的机载定位定向系统(POS)联接,可以快速获取大面积地球表面三维数据。本文对光学三维测量技术和航空三维激光扫描技术做一简单介绍,给出三维激光扫描技术在航空航天领域的几个应用。     

考虑径向畸变的摄像机标定及在三维重建中的应用

建立了摄像机的径向畸变模型，采用“两步法”标定技术分解了摄像机的内外参数，将有效焦距、畸变系数、不确定因子统一于线性方程组中。使算法简便、快速、准确。通过试验比较了线性模型和畸变模型在三维重建中的误差。     

线切割与真空热扩散焊组合工艺制备微模具

采用线切割和真空压力热扩散焊组合工艺制备了高深宽比的三维微结构。分别研究了线切割与热扩散焊工艺并获得了较好的工艺参数用于制备微模具。首先,在脉冲宽度为10μs,脉冲间隔为40μs,线切割电流为0.28A,电压为60V的条件下,对100μm厚的铜箔进行线切割,获得了多层二维微结构。然后,在热扩散温度为850℃,热扩散时间为10h,压力为1.0μPa的工艺参数作用下,对多层铜箔二维微结构进行真空压力热扩散焊接,通过多层二维微结构的叠加形成微模具,并制备了六棱台微型腔模具及微型级联齿轮模具。实验结果表明:三维微模具表面形貌较好,制作结果较理想,与设计模型基本相符。最后,通过超声模压成型分别获得了二阶和三阶的塑料级联齿轮。这些微塑件质量良好,验证了该工艺方法的可行性。     

积木式教育机器人三维仿真平台框架研究

针对目前教育机器人缺少仿真环境、训练过程不完善的缺点,提出了一种集机器人设计、控制程序编写、动态仿真为一体的机器人三维仿真平台。分析了教育机器人三维仿真平台的功能需求。利用面向对象的建模方法和组件化思想,建立了分层的机器人三维仿真平台体系结构和以数据为中心的功能框架,并给出了仿真平台的应用流程。实际应用表明,该仿真平台具有很好的应用前景和推广价值。     

用于微镜制作的叠层光刻胶工艺及残余应力控制

对应用于微反射镜制作的叠层光刻胶牺牲层工艺及微反射镜表面残余应力控制进行了研究.讨论了光刻胶牺牲层在电镀时的污染问题,提出了用电镀结束后重新制作光刻胶牺牲层的方法来保证牺牲层表面质量.同时提出蒸发电镀相结合的工艺,解决了上层光刻胶溶剂穿过中间结构层浸入底层光刻胶的问题,并通过控制蒸发与电镀过程中应力状态不同的两层金属薄膜的厚度解决了微反射镜镜面存在残余应力问题.最后成功释放了620 μm×500 μm×2μm,悬空高12 μm的微反射镜结构.     

Design of multi-scaffold fabrication system for various 3D scaffolds

Three-dimensional (3D) porous scaffolds have been fabricated recently for tissue engineering applications through solid free-form fabrication (SFF) technologies. A multi-scaffold fabrication system for the fabrication of scaffolds, such as polymer, polymer/ceramic, ceramic, and nanofiber, was designed in this study. The various components, including a dispenser with a maximum pressure of 750 kPa, a thermostat with a maximum temperature of 250°C, a high-voltage power supply with a maximum output of 60 kV, and a syringe pump with small flow control, play important roles in determining the process characteristics of scaffolds. The system can process applicable biomaterials with extremely high accuracy with a precision nozzle. Several 3D scaffolds, including PCL, PCL/PLGA/β-TCP, β-TCP, and PCL nanofibers, were fabricated. The morphology and pore size of fabricated scaffolds were observed through scanning electron microscopy. Results show that the scaffolds manufactured in this study can be effectively utilized as bone regeneration scaffolds.     

The fabrication of a multi-spectral lens array and its application in assisting color blindness

This article presents a compact multi-spectral lens array and describes its application in assisting color-blindness. The lens array consists of 9 microlens, and each microlens is coated with a different color filter. Thus, it can capture different light bands, including red, orange, yellow, green, cyan, blue, violet, near-infrared, and the entire visible band. First, the fabrication process is described in detail. Second, an imaging system is setup and a color blindness testing card is selected as the sample. By the system, the vision results of normal people and color blindness can be captured simultaneously. Based on the imaging results, it is possible to be used for helping color-blindness to recover normal vision.     

3D finite element temperature field modelling for direct laser fabrication

In order to describe the thermal dynamics behaviour in direct laser fabrication (DLF), a 3D finite element temperature field model is proposed to be built/developed based on global model and sub-model pattern. The global model exhibits the heat conduction characteristics of parts in the whole thermal history according to scanning path planning. Contact pairs and gap elements, which consider the effect of the temperature and porosity-dependent thermal conduction, are designed in the model to explain powder-to-solid intrinsic transition. In addition, the elements removed and reactivated technology is applied in the model so as to embody the material stepwise increasing feature. A laser-repairing case developed by ABAQUS demonstrates the global model’s thermal history, and the influence of non-linear behaviour of thermal properties in pure nickel on the temperature distribution is estimated as well. Adopting the thermal physical parameters with solid–liquid phase change will make the melted pool temperature higher than that where the solid–liquid phase change parameters are not considered.     

三维微细电火花加工伺服控制系统设计及实验研究

针对微细电火花加工伺服控制系统的要求,进行了微细电火花加工伺服控制系统总体设计.伺服控制系统特点是执行机构采用步进电机+压电陶瓷的宏微细合式驱动机构,实现了大行程和小步距的有机结合,能够提高电火花加工机床的加工性能.同时Z轴增加一个振动源,实现自动排屑和微调加工间隙.通过实验验证,证明系统运行良好,运动平台能够达到较高的精度,并实现了简单的极微细电火花加工.     

3D实体技术在CAPP中的应用

从产品的开发开始,以信息化技术作为支撑,以工艺技术为中心,运用UG/CAD、UG/CAM,并且在CAPP系统中用基于PDM的3D实体模型代替传统的二维图形。阐述实现产品的全过程信息集成。     

电磁型平面微电机及其制作工艺

为得到一种尺寸小、输出力矩大、转速高的直流可调速微电机,提出了一种利用微机械加工工艺制作微电机的方法。定子和转子都做成平面结构,定子线圈采用了平面型、无槽式集中绕组;线圈之间采用了三相星形连接方式,采用了微机械LIGA工艺和硅微机械加工工艺;转子采用钕铁硼永磁材料,进行轴向充磁,成辐射状间隔分布。装配时转子分布于定子两侧,不但减小了电机尺寸,还有利于定子的散热。把装配完毕的微电机接通三相半控控制电路对其转速和力矩进行了测试,测试结果表明,电机运转平稳,输出力矩大。     

微细电火花加工圆柱电极的损耗研究

应用电磁场理论对微细电火花加工(Micro Electrical Discharge Machining,Micro-EDM)损耗机理进行分析,建立了加工中工具电极电场分布的数学模型.应用Comsol Multiphysics软件对此模型进行了计算与模拟,分析了电场强度的变化对电极形状变化的影响,并指出在靠近放电点位置和底部电极形状改变后,集肤效应的作用被削弱.实验验证了仿真结果和所提出损耗机理的正确性,为电极损耗补偿策略和加工精度的提高提供了理论依据.