电火花线切割拐角加工精度的实时预测

提出了一种电火花线切割加工拐角加工精度的实时预测方法,并为此建立了实时预测系统.系统根据实时采集的放电能量等加工参数,通过电极丝振动解析及数控轨迹与电极丝位置关系的分析,可得出电极丝形变量与加工误差,从而可将拐角加工形状实时地再现于计算机上,实现了拐角加工精度的实时预测.     

电火花线切割锥度加工编程技术的研究

分析了电火花线切割加工中常规锥度对应点的计算和电极丝的间隙补偿问题,将上、下表面的加工轨迹转化为对应的XY和UV平面的加工轨迹,用Visual C 实现常规锥度工件轨迹的生成,将锥度工件偏移补偿后得到的电极丝中心轨迹转化为工作台在XY平面和上导向器在UV平面的控制轨迹.实现线切割机锥度加工中的4轴联动加工技术.     

电火花线切割加工技术最新研究进展

介绍了近年来国内外电火花线切割加工技术的最新研究进展,包括加工变厚度工件过程中工件厚度的在线辨识及参数优化与控制,提高加工拐角精度电极丝偏差的在线检测,基于浮动阀值的放电间隙状态检测技术,在机床加工中表面质量修正技术以及混粉对提高加工质量以及加工效率的研究等.     

电火花线切割小圆弧加工自适应控制

随着技术的不断进步,电火花线切割-高速磨削复合加工技术逐渐被用于航空发动机涡轮盘榫槽加工.与传统的拉削加工方式相比,电火花线切割不仅能大幅降低工具和机床的成本,而且加工工艺更为灵活.但由于榫槽加工轨迹是由直线段、小圆弧段共同组成,采用电火花线切割技术加工小圆弧拐角时易发生电极丝弯曲现象,使切割出的小圆弧半径小于设定值....     

基于六自由度串联机器人的电火花铣削加工实验研究

传统电火花铣削加工需在特定加工机床上实现,被加工工件尺寸与形状受机床限制,故将电火花铣削加工与六自由度串联机器人有机结合在一起,以此开展了一系列电火花铣削加工实验.首先,通过直线沟槽铣削加工探究电极尺寸、脉冲宽度和电极扫描速度对材料去除率和电极损耗率的影响;其次,通过曲线沟槽铣削加工探究本装置的加工精度,通过方形平面槽铣削加工研究铣削轨迹、轨迹重叠方式对加工的影响;最后,将基于六自由度串联机器人的电火花铣削加工装置应用于曲面工件的铣削加工.结果表明:基于六自由度串联机器人的电火花铣削加工具有很高的加工自由度且能实现较高的加工精度,具有很大的应用潜力.     

电火花铣削加工工艺与算法研究

介绍了电火花铣削加工工艺及其有关计算方法。在大量实验的基础上,研究了微细电火花分层铣削加工,采用电极底面放电方式、电极轨迹规划、电极的损耗及补偿策略和合理选择分层厚度及电极微进给量等关键技术,提高了加工精度和效率。     

电火花线切割用镀层丝设计

分析了复杂多拐角工件电火花线切割加工中存在的问题,提出了有效的解决方案。从应用角度出发,设计了特殊的表层电极丝材料,优化了镀层丝的性能,满足了电火花线切割加工复杂多拐角工件的应用要求,提高了加工精度和表面质量。     

精密模具EDM专用补偿软件系统的开发

针对电火花成形加工(SEDM)电极平动的不同类型,提出了电极补偿修正原理,开发了SEDM专用补偿软件系统,并进行了实验验证.实验表明,该系统能有效降低因电极平动所产生的误差,明显提高SEDM加工精度.     

模具线切割加工中电极丝偏移补偿量的确定

通过电极丝中心运动轨迹的分析与计算,确定其合理的偏移补偿量,以提高冲裁模具的加工精度.     

XYUV四轴快走丝线切割导轮接触点误差及补偿

导轮接触点误差及其补偿是ＸＹＵＶ四轴快走丝线切割锥度加工精度控制中的主要难题之一。本文将重点讨论导轮接触点误差及其补偿中的若干问题，大量锥度试件的加工精度实践表明，采用导轮接触点误差补偿后，ＸＹＵＶ四轴快走丝线切割锥度加工工艺已具实用价值。     

Accuracy improvement of wire-EDM by real-time wire tension control

In this paper, a closed-loop wire tension control system for a wire-EDM machine is presented to improve the machining accuracy. Dynamic models of the wire feed control apparatus and wire tension control apparatus are derived to analyze and design the control system. PI controller and one-step-ahead adaptive controller are employed to investigate the dynamic performance of the closed-loop wire tension control system. In order to reduce the vibration of wire tension during wire feeding, dynamic absorbers are added to the idle rollers of wire transportation mechanism. Experimental results not only demonstrate that the developed control system with dynamic absorbers can obtain fast transient response and small steady-state error than an open-loop control system, they also indicate that the geometrical contour error of corner cutting is reduced with approximately 50% and the vertical straightness of a workpiece can be improved significantly.     

大厚度工件电火花线切割加工多次切割腰鼓度成因研究

为研究往复走丝电火花线切割加工在大厚度工件多次切割时形成腰鼓度的成因,对厚度为185 mm的工件进行了多次切割实验,通过改变工作液电导率、电极丝走丝速度、修刀补偿量和电极丝直径等条件,对加工形成的腰鼓度进行了测试及分析。结果表明:大厚度切割过程中,两极之间的脉冲放电爆炸力是产生腰鼓度的主要原因,通过增加电极丝直径以提高电极丝截面惯矩,可减小因放电爆炸力对电极丝形成的挠度,从而减小腰鼓度误差值。     

摄像机标定中亚像素级角点检测算法

针对摄像机标定模板图像的角点检测问题,提出了两种简便而有效的亚像素级精度的提取算法.先用传统的Harris算子检测出像素级的角点坐标,然后再求取亚像素级角点坐标.一种方法是用二次多项式去逼近周围3×3领域内的角点反应函数,用线性解法求得亚像素级角点坐标;另一种方法是从亚像素角点到周围像素点的矢量应垂直于图像的灰度梯度这个观察事实得到的,通过最小化误差函数的迭代方法来获得亚像素级精度的坐标值.文中提出的亚像素级角点检测方法定位精度高,摄像机标定试验中,得到的重投影平均偏差小于0.15个像素.     

基于ANSYS的电极丝振动现象研究

通过理论和数值分析,阐述了高速走丝电火花线切割机电极丝的振动情况。利用有限元软件ANSYS模拟电极丝振动,得到了理论计算与ANSYS模拟的误差值。数值分析发现电极丝张力对频率有较大的影响,调节上下导轮间电极丝的跨度可改变其频率,而工件可起到改变电极丝原有模态振型的作用。这些结论为抑制电极丝的振动提供了理论依据。     

电极丝随动放电切槽技术试验研究

微细电火花线切割加工时电极丝存在难以避免的振动,且振动幅度随着切割工件厚度的增加而变大,这导致加工出现腰鼓形误差,工件加工效率与加工质量也受影响.针对电极丝的振动问题提出一种电极丝随动放电切槽技术,通过顶丝头的导丝孔和导丝槽抑制电极丝振动,利用电极丝放电蚀除工件完成了长度70 mm、直径0.1 mm的半圆截面长通道的加...     

三维有限元网格图形的剖切及场变量可视化

为了更好地分析三维有限元模拟过程中工件内部场变量的变化分布规律, 本文着重介绍了在屏幕工件上用鼠标任意点取3个点构造一平面, 然后应用该平面将基于八节点三维六面体单元的工件进行剖切的方法, 给出了剖切后网格图形上场量值所对应的等值线、彩色云图及速度矢端图等的生成算法。文中算例表明, 该算法灵活、可靠, 具有很好的可行性。     

Dimensional errors in longitudinal turning based on the unified generalized mechanics of cutting approach.: Part I: Three-dimensional theory

During the machining of a part, a new surface is generated together with its dimensional deviations. These deviations are due to the presence of several phenomena (workpiece deflection under strong cutting forces, vibration of the machine tool, material spring-back, and so on) that occur during machining. Each elementary phenomenon results in an elementary machining error. Consequently, the accuracy of the manufactured workpiece depends on the precision of the manufacturing process, which it may be controlled or predicted.The first part of this work presents a new model to evaluate machining accuracy and part dimensional errors in bar turning. A model to simulate workpiece dimensional errors in longitudinal turning due to deflection of the tool, workpiece holder and workpiece is shown. The proposed model calculates the real cutting force according to the Unified Generalized Mechanics of Cutting approach proposed by Armarego, which allows one to take into account the three-dimensional nature (3D) of the cutting mechanism. Therefore, the model developed takes advantage of the real workpiece deflection, which does not lie in a plane parallel to the tool reference plane, and of the real 3D cutting force, which varies along the tool path due to change in the real depth of cut. In the first part of the work the general theory of the proposed approach is presented and discussed for 3D features. In the second part the proposed approach is applied to real cases that are mostly used in practice. Moreover, some experimental tests are carried out in order to validate the developed model: good agreement between numerical and experimental results is found.     

Wire electrical discharge machining of metal bond diamond wheels for ceramic grinding

The application of cylindrical wire Electrical Discharge Machining (EDM) for profile truing of metal bond diamond wheels is presented. Instead of using the mechanical force to break the diamond and matrix in the grinding wheel, the wire EDM process uses the thermal energy or electrical sparks between the wire and rotating grinding wheel to remove the metal bond and form the wheel. The design and manufacture of a corrosion-resistant, precise spindle with the high-electrical current capability for wire EDM truing of grinding wheel is first introduced. Three truing configurations were designed to study effects of wire EDM process parameters and to investigate the level of form accuracy and corner radii achievable by the wire EDM truing of diamond wheels. Results show that the wire EDM process can efficiently generate the μm-scale precision form on the diamond wheels. The wheel, after truing, was used to grind the silicon nitride workpiece. Grinding forces and wheel wear rate were measured. In the beginning of the grinding, high wheel wear rate was identified. The subsequent wheel wear rate was considerably lower and stabilized.     

Influence of the Workpiece Stiffness on the Electromagnetic Sheet Metal Forming Process into Dies

Electromagnetic sheet metal forming is a high speed forming process using pulsed magnetic fields to form metals with high electrical conductivity such as aluminum. Thereby, workpiece velocities of more than 300 m/s are achievable, which can cause difficulties when forming into a die. The kinetic energy, which is related to the workpiece velocity, must be dissipated in a short time slot when the workpiece hits the die; otherwise undesired effects, for example rebound can occur. One possibility to handle this shortcoming is to locally increase the stiffness of the workpiece. A modal analysis is carried out in order to determine the stiffness of specific regions of the workpiece so that an estimation concerning the feasibility of the desired geometry is possible in advance without doing cost and time consuming experiments. Thereby, the desired geometry of the workpiece will be fractionized in significant sectors. This approach has to define the internal force variables acting on the cutting edge, which are required to constrain the numerical model. Finally, a method will be developed with the objective of calculating the stiffness of each sector. The numerical results will be verified by experiments. This article was presented at Materials Science & Technology 2006, Innovations in Metal Forming symposium held in Cincinnati, OH, October 15-19, 2006.     

液力变矩器点固TIG焊的同心精度设计方法

液力变矩器工作在高速旋转状态，总成焊后的上盖和泵轮的同轴跳动具有严格的精度要求。本文详细讨论了影响液力变矩器填丝ＴＩＧ点固焊后上盖和泵轮的同心精度的要素，包括工件状态、工件结构、机械状态、焊接工艺等影响要素，引入了精度误差理论，对液力变矩器填丝ＴＩＧ点固焊接系统的同心精度综合进行定量分析和设计，建立了该系统的同心精度控制数学模型，讨论了各影响因素的同心精度综合方法和合成系数的确定方法。通过对该模型的分析和解析，得到了在较低成本下保证上盖和泵轮的同心对中精度的工装设计要求，并研制了符合实际生产要求的加工系统。