Investigations aiming to increase electrochemical machining accuracy

Under conditions of electrochemical sinking, the standard deviation of inter-electrode gap thickness decreases with the decrease of machined area, while the machining accuracy increases. Advantage may be taken of this fact when using an electrode with a working area smaller than its machined area and when using different electrode kinematics than for sinking. For instance, the working electrode should move above the machined area at a velocity v_p. Theoretical and expeirmental research shows, that electrochemical machining (ECM) processes can show a significant increase of machining accuracy when compared to classical electrochemical sinking. This results mainly from the fact that parameters of the process can be chosen in such a way that the uneven distribution of physical properties in the machining space does not radically affect changes of inter-electrode gap thickness. Because the productivity of the discussed case is lower than for classical electrochemical sinking, it should be applied for finishing operations in which a small material excess is removed.     

电化学放电线切割加工方法实验研究

针对非导电硬脆材料的微细线切割加工,设计并搭建了电化学放电线切割加工装置,对电化学放电线切割加工过程中的电压-电流曲线与电极丝放电长度之间的关系进行了实验研究。实验结果表明,随着直流电压的增大,电压-电流曲线呈现出线性区、饱和区、跃变区和放电区等明显的区域性特征变化,稳定放电仅在电压高于一定值的放电区内发生,且电极丝放电长度越大,发生跃变放电时的临界电压越高。对普通玻璃和石英玻璃的加工实验表明,通过增大放电能量,能够获得更高的材料去除率,但也会导致工件加工精度和表面质量的下降。     

Experimental research on the optimization of precision electrochemical machining feed mode of diamond-hole grille

Underwater laser machining process is a promising method to cut materials with less thermal damage. A variation of underwater technique is overflow-assisted laser ablation. This process can introduce a higher thermal convection and more uniform water layer than the typical underwater method. Such characteristics can encourage the damage-free fabrication and also stabilize the laser ablation in water. In this study, cut profile and temperature distribution of workpiece induced by the overflow technique were investigated. Titanium alloy (Ti-6Al-4V) used as a work sample was grooved by a nanosecond pulse laser under different overflow conditions. The effects of laser power, laser repetition rate, and water flow velocity were experimentally and numerically examined. A clean and smooth cut surface can be fabricated when the overflow technique was used. Microcracks and porosities found on the laser-ablated area were also addressed in this study. The temperature field of titanium alloy under the different ablation conditions was simulated by using the finite difference computation. The transient heat conduction model was implemented together with the enthalpy method and temperature-dependent material properties. By using the developed model, the groove depths obtained from the experiment and simulation were in a good agreement.     

高回转精度多阶柱状微电极电化学高效制备试验研究

为实现高回转精度多阶柱状微电极的高效加工,对多阶柱状电极电化学刻蚀过程进行了深入的研究与改进。首先,根据电化学刻蚀理论推导了加工电流对电极直径变化的影响规律;通过试验证明了电极旋转可提高电流变化速率及有效起始电流进而提高加工效率,定性分析了电极旋转对电极回转精度的影响,提出了分阶变转速高效加工高回转精度多阶柱状微电极的方法;通过试验分析了各加工参数(电极转速、加工电压和切断电流)对电极形状及尺寸的影响;最后,在优化后的加工参数下,成功加工得到末端直径小于15μm且同轴度误差在1μm以内的多阶柱状微电极,与常规电化学刻蚀工艺相比,显著提高了加工效率。试验证明旋转电化学刻蚀是一种能够较好地提高微电极加工效率及回转精度的新工艺。     

HRV3控制对于提高加工精度的研究

阐述了伺服系统HRV控制方式的原理及其对改善加工性能方面的特性,并介绍HRV3控制方式的设定方法,利用实验的方式验证了该控制方式对试件加工精度的提高及加工速度的改善。     

提高实体车制保持架方兜孔加工精度的研究

保持架的制造精度,特别是兜孔的制造精度直接影响轴承的性能。针对兜孔制造精度相对较低及精度不稳定的现状,采用先进设备和合理的刀具,保证保持架兜孔的制造精度,不仅保证了轴承的性能,而且提高了保持架的加工合格率和轴承的使用寿命。     

提高数控机床加工精度技术研究

基于多体系统理论，建立了多坐标数控机床误差模型。介绍了3坐标数控机床9线辨识方法，研究了回转坐标6项误差的辨识方法。在4坐标数控机床上实现了几何误差的软件补偿。试验结果说明误差模型的准确性和补偿方法的实用性。     

电解加工小孔方案优化及实验研究

小孔法是工程中残余应力测量最常用的方法,传统机械加工小孔会引入塑性变形与附加应力,影响测量结果的准确性.采用无应力产生的电解加工方法进行小孔加工在残余应力测试方面具有显著优势.利用不受加工结构限制的3D打印技术制造中空循环电极,搭建动液电解加工小孔装置;利用Fluent软件进行流场仿真,以电解加工表面电解液流速大小和流场均匀性为评价标准,优化中空循环电极内部流道结构;根据流场与电场仿真结果表明中空循环电极环形隔板壁角β对电解加工精度有较大影响.以纯铁(DT4E)为实验材料,进行不同壁角β下电解加工小孔实验,壁角β为60°时小孔孔形最佳.     

圆柱曲面螺旋槽数控加工技术

本文针对圆柱曲面螺旋槽的加工从数控机床和加工刀具的选择、走刀方式、加工方法等方面进行研究,进而根据螺旋槽的形状以及加工刀具的不同提出了相应的数控加工编程方法.     

电解加工间隙中的传质过程及其对电解加工的影响

这里应用流体力学、传质学和电化学理论,分析了电解加工间隙中处于紊流状态的电解质溶液内的传质过程。在此基础上建立了阳极电流密度的计算方法,并讨论了外加电压、电解质浓度、流速等参数对电解加工的影响。     

Predicting radial overcut in deep holes drilled by shaped tube electrochemical machining

Shaped tube electrolytic machining (STEM) is a versatile and relatively low cost process for drilling deep, high aspect ratio holes. Since the radius of a drilled hole is the sum of the tool radius and radial overcut, one crucial aspect of dimensional accuracy is radial overcut. However, models of overcut in the literature are scarce and have primarily been restricted to shallow holes. Moreover these models were purely empirical and therefore restricted in scope. A fundamental mathematical model that uses STEM operating parameters (voltage, tool diameter and feed rate, bare tip length and electrolyte composition) as inputs to predict radial overcut has been developed. Predictions from the proposed radial overcut model are much closer to experimental data compared to those from the models available in the literature. A novel contribution of this study has been the formulation of a methodology to determine the magnitude of current flowing out radially from the bare tip length using experimentally measured total current values.     

微沟槽热管充液旋压成形实验研究

对微沟槽热管充液旋压成形工艺进行了研究,通过试验对影响充液旋压成形加工的三种关键性因素进行了研究与分析.结果表明,在影响充液旋压加工沟槽式热管的三种因素中,旋压当量直径和刀具与滚珠间相对位置主要影响热管内微沟槽形状和尺寸大小,如槽深、槽宽和深宽比;刀具与滚珠间相对位置和拉伸速度影响充液旋压加工过程中铜管是否被拉断;拉伸速度对热管表面粗糙度影响很大.     

超声振动车削光整技术的试验研究

利用超声振动进行车削光整加工试验,对影响光整表面粗糙度的因素进行了大量的试验研究,通过对比试验和正交试验确定了合理的切削参数.分析了影响加工表面质量的一些因素,为推广使用超声振动车削光整工艺做出了试验上的分析和论证,分析了超声车削光整工艺的优越性和规律性。     

Experimental and numerical analyses of the pressure distribution in electrochemical machining

Measurements have been made of the pressure distribution of the electrolyte solution flowing along the inter-electrode gap during electrochemical machining. A theoretical model for the pressure distribution, which takes into account the growth of the hydrogen gas layer along the cathode electrode, is proposed. A method of solution of the model, based on optimisation techniques, is discussed.The experimental results and the theoretical model are correlated in terms of the variation of the interelectrode gap, thereby providing a prediction of the pressure distribution together with values for gas void fraction index, the slope of the gas bubble layer and the friction factor.A comparison of the measured and predicted pressure variation is presented. Numerical values for the above parameters are then discussed in the light of other observations of the process.     

正交车铣加工凸轮型面的试验研究

针对凸轮型面加工精度难以保证、加工效率低等问题,采用正交车铣技术对凸轮型面进行切削加工.建立了正交车铣加工凸轮型面的运动模型,并通过试验对运动模型的正确性进行了验证.结果表明,采用正交车铣加工凸轮型面可以获得较小的表面粗糙度值,该方法是一种加工凸轮型面的高效方法.     

Neural-network diagnostics of electrochemical machining

In the high-precision electrochemical shaping of new high-strength and hard materials, diagnostics may be based on neural-network identification algorithms incorporated in the automated control system of the equipment.     

大深度小喉径铸件锥孔数控车削加工实践探索

汽轮机调节系统中的扩散管零件,其内孔为锥面,深度大,喉部直径小,悬伸长,工艺系统的刚性非常差,加工中极易产生振动,在对此类零件的加工工况分析的基础上,提出了分段加工的工艺措施,减小了加工中的振动,保证了加工效果,提高了加工的效率。     

采用刀具微位移补偿装置提高加工精度的技术研究

采用电致伸缩陶瓷微位移驱动器控制刀具进行实时误差补偿的方法明显提高轴类零件加工精度.阐明了微位移系统的补偿原理,描述出电致伸缩陶瓷的优点及蠕变特性,通过实验分析了电致伸缩陶瓷补偿系统在空载状态和轴向受弹性压力载荷时电压位移曲线的特性与差异,以此实现电致伸缩陶瓷驱动器的高精度开环微位移控制,在实际应用中亦有较高的实用价值.     

FDM工艺参数对成型精度影响的试验探究

在分析了打印速度、分层厚度、填充密度等工艺参数基础上,通过等体积率公式,得到不同打印速度下,打印截面分层厚度和挤出丝宽之间的理论关系,然后根据丝宽搭接模型,对水平方向的成型精度进行理论分析。设计试验通过配置30、40及50 mm/s的打印速度,0.1、0.2及0.3 mm的分层厚度值和90%的填充密度3个工艺参数,对理论分析进行试验验证。试验结果表明,分层厚度为0.2 mm,打印速度区间在30~40 mm/s,填充密度为90%时的参数组合,在保证成型件竖直方向精度的基础上得到了最优的水平方向精度。