High frequency group pulse electrochemical machining

In the process of machining ultrathin metal structure parts, the signal composition of high frequency group pulse, the influence of frequency to reverse current, and the design of the cathode in high frequency group pulse electrochemical machining (HGPECM) are discussed. The experiments on process were carried out. Results indicate that HGPECM can greatly improve the characteristics of the inter-electrode gap flow field, reduce electrode passivation, and obtain high machining quality. The machining quality is obviously improved by increasing the main pulse frequency. The dimensional accuracy reaches 30–40 μm and the roughness attained is at 0.30–0.35 μm. High frequency group pulse electrochemical machining can be successfully used in machining micro-parts. __________ Translated from Transactions of Beijing Institute of Technology, 2006, 26(7): 585–588 [译自: 北京理工大学学报]     

Investigations into machining of composites

Fibre reinforced plastics (FRP) have an important place in the field of engineering materials. Initially, the main emphasis in research was on the development of materials. Currently, however, more attention is being paid to the industrial production of FRP products. Normally, conventional methods for machining of these materials are used, but reports have indicated poor performance of these conventional types of cutting tools during machining of FRP. In this paper, a new approach using electrochemical spark machining (ECSM) for cutting and drilling holes in composites is proposed.

The feasibility of using ECSM for machining FRP was first ascertained. Then a parametric study of the process was performed by planning the experiments using a ‘design of experiments’ concept as well as a ‘one variable at a time’ approach. Kevlar-fibre-epoxy and glass-fibre-epoxy composites as work materials, copper as the tool material and an aqueous solution of NaCl as electrolyte were used.

It is concluded that ECSM is a viable solution for cutting FRP. However, for achieving the desired accuracy, surface finish and economics of the process, the machining parameters need to be optimized.     

高速加工时各切削参数对切削力影响的模拟研究

切削力是切削过程中重要的物理参数之一。本文应用数值模拟,对高速切削加工过程中切削参数(切削速度、进给量、切削深度)对切削力的影响进行了研究,给出了切削力随切削速度、进给量、切削深度的变化规律,对优化高速切削工艺及建立高速切削数据库具有指导意义。     

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.     

高速切削加工技术及其应用

高速切削加工是切削加工发展的一个重要方向,本文详介绍高速切削加工机理、特点、在国内外的发展和应用领域以及其发展趋势等.     

发动机缸孔轮番式珩磨加工工艺的实现

轿车发动机缸孔珩磨装备是多孔缸体加工的常用设备,具备四珩磨轴同步加工功能,根据珩磨加工工艺,通常4个珩磨轴分两组,分别完成粗珩加工和精珩加工。为了提高加工效率,可双轴同步加工一个工件,或者轮番式分别加工不同的工件。根据对国内汽车厂家所使用的汽车珩磨加工自动线的调研,结合实际珩磨加工工艺,分析总结出,采用轮番式加工工艺流程,能实现加工效率的最大化,在实际开发轿车发动机缸孔珩磨装备中得到了成功应用。     

高速干切削加工技术

作为一种新型的绿色制造技术，高速干切削技术对实施人类可持续发展战略有重要的意义.阐述高速干切削加工及其关键技术（包括刀具技术、机床技术和工艺技术等）。     

Automatic restart control system for electrochemical machining

This paper describes the development of a microprocessor-based automatic restart control system (arcs) capable of eliminating flaws caused by restarts during the electrochemical machining (ecm) process. This makes ecm a viable cost-effective technique for producing precision parts previously handled by conventional methods.     

整体叶轮叶片型面的精密展成电解加工

介绍采用四轴联动方式精密展成电解加工整体叶轮叶片型面的实现方法,并针对某航空发动机上的一整体叶轮进行了叶片型面的精加工试验,取得了良好的试验结果。     

高速铣削中切削力的研究

在高速铣削试验的基础上，研究高速切削时切削速度对切削力的影响。结果表明，在切削速度较低的情况下，切削力随切削转速的增加而增大，但达到某一临界速度后，随着切削速度继续增大，剪切角增大，造成切向切削分力下降。不同刀具材料与工件材料的匹配在不同切削条件下有不同的临界切削速度。     

Study of the effects of tool longitudinal oscillation on the machining speed of electrochemical discharge drilling of glass

In this study, longitudinal oscillation applied to the cathode electrode during the electrochemical discharge micro drilling of glass and the effects of electrolyte flushing alteration in both discharge and hydrodynamic regimes of the process have been investigated. In this regard, numerous sets of experiments have been conducted using different vibration frequencies and amplitudes. In addition, two geometrically different tools including cylindrical rod and micro drill were used as machining electrode (cathode). In the case of cylindrical rod, two types of longitudinal waveforms including square and sinusoidal ones were applied to the tool. The experiments were resulted in a noticeable improvement in material removal rate (MRR) using square waveform and a slight improvement in the case of sinusoidal waveform. Moreover, the obtained MRR by means of vibrating micro drill has been compared with those achieved by non-vibrating one in several oscillation frequencies and amplitudes. The results showed that the vibration of the micro drill cannot further improve the electrolyte flushing and MRR in comparison with non-vibrating one because of the inherent electrolyte flushing in micro drill through its flutes which is constant in vibrating and non-vibrating cases.     

Feed rate of wire electrochemical machining using pulsed current

The effect of various parameters on the feed rate in electrochemical machining has been investigated. Parameters considered were velocity of the electrolyte flow, nozzle diameter, material, diameter and tension of the wire, pulse period and peak value of the applied voltage. On the assumption that the feed rate is limited by accumulation of generated sludge or gas, the feed rate equation and favourable pulse conditions were derived and verified experimentally. The rate was improved by applying a shorter pulse period than the ‘residential’ time of the electrolyte between electrodes. Above the critical pressure, at which the feed rate is a maximum, the adverse effects of wire vibration cannot be neglected. Measures proposed to prevent it were reduction of nozzle diameter and length of wire span, and increase in applied voltage and wire tension.     

混气电解加工探讨

电解加工是利用金属在电解液中发生阳极溶解反应而去除工件上多余的材料、将零件加工成形的一种方法。电解加工的加工精度不仅与加工间隙有关,还与机床、工艺装备、工具阴极、工件、工艺参数等诸多因素有关,通常采用混气电解加工、脉冲电解加工、小间隙电解加工和改进电解液等措施提高加工精度。其中混气电解加工是将具有一定压力的气体与电解液按一定比例混合在一起,然后将这种混合物加入到工件的加工间隙中去进行电解加工的一种方法。混气电解加工可以缩小加工间隙,提高电解加工的加工精度和复制精度,但混气电解加工的微观不平度和不直度还不理想。从气液混合比、混气电解加工的特性以及混气电解加工的工艺三个方面对混气电解加工的原理进行一定的探讨,希望摸索一种提高电解加工精度的方法。     

高速干切削技术及其实现

在切削加工中大量使用切削液进行冷却、润滑,不但提高了加工成本,也带来了环境污染,消除这些问题的合理措施是采用高速干切削方式。提出了干切削技术的新内涵,分析了实现高速干切削的机床技术、刀具技术和工艺技术。通过该技术实现了绿色制造,保证了企业的经济效益和社会效益最优化。     

高速切削刀具的发展现状

对国内外高速切削刀具的发展现状进行了综合评述 ,重点介绍了高速切削刀具材料和高速切削刀具技术 (包括刀具动平衡技术、刀柄系统、刀具安全性、可转位面铣刀结构、刀具监测技术等 )的开发及应用     

SPH method applied to high speed cutting modelling

The purpose of this study is to introduce a new approach of high speed cutting numerical modelling. A Lagrangian smoothed particle hydrodynamics (SPH)-based model is carried out using the Ls-Dyna software. SPH is a meshless method, thus large material distortions that occur in the cutting problem are easily managed and SPH contact control permits a “natural” workpiece/chip separation. The developed approach is compared to machining dedicated code results and experimental data. The SPH cutting model has proved is ability to account for continuous to shear localized chip formation and also correctly estimates the cutting forces, as illustrated in some orthogonal cutting examples. Thus, comparable results to machining dedicated codes are obtained without introducing any adjusting numerical parameters (friction coefficient, fracture control parameter).     

旋转超声电解复合加工小孔的仿真加工

为研究旋转超声电解复合加工小孔的成型过程,进行了旋转超声电解复合加工小孔试验,得到了不同加工时间孔的截面,并根据试验参数,进行了基于ANSYS的二维仿真加工和三维仿真加工。对小孔的入口直径、底面直径和加工深度进行了对比分析,结果表明由于三维仿真加工中采用了管电极,并考虑了电解加工中阴极超声高频振动对电解液电导率的影响,故其仿真结果更加接近试验值,间接证明了旋转超声电解复合加工小孔三维仿真加工的可靠性,展示了不同时刻的三维加工型腔,为旋转超声电解复合加工的成型过程和成型规律的研究提供了参考。     

高速加工技术与电主轴

高速加工机床的核心功能部件是电主轴,研究高速加工的关键技术以及电主轴的部件在设计和制造中的一些关键技术,了解相关最新技术及其发展趋势和动态,为合理选用电主轴,满足生产工艺的需求具有实践指导意义。     

Investigation of plastic electrode tools for electrochemical machining of silicon

A concept of plastic electrode tools for electrochemical machining is investigated and applied to machining of c-Si. The electrode tools consist of a plastic body with an optimized electrical conductive coating. This concept allows for low cost electrodes which can be even realized by rapid prototyping techniques. The micro electrochemical machining of p-type silicon by these innovative metalized plastic electrode-tools is studied. The technological schemes of the machining and design of metalized plastic electrode-tools are developed. Theoretical investigation of thermal conditions and limitations of the electrode-tools during the machining process are performed. Based on these investigation, recommendations on the minimum thickness of the conductive layer of the electrode-tools from Cu, Ni and Pt are defined. Experimental optimization of the process parameters during the machining is performed and feasibility of the metalized plastic electrode-tools for micro electrochemical machining is demonstrated.     

高速加工切削用量选择分析

高速加工切削用量的选择主要考虑加工效率、加工质量、刀具磨损和加工成本。不同刀具加工不同工件材料时,切削用量会有很大差异。切削用量的选择是高速加工中的重要内容,切削用量的大小对加工效率、加工质量、刀具磨损和加工成本均有显著影响。本文对高速加工的切削用量选择问题进行了分析,给出了若干原则和建议。