旋转超声电解复合加工三维流场仿真

单因素试验表明在相同加工条件下旋转超声电解复合加工小孔效率优于旋转电解加工小孔,为研究阴极旋转和高频振动对旋转超声电解复合加工流场的影响,基于有限元ANSYS CFX软件建立了旋转超声电解复合加工流场仿真模型,分析了阴极旋转和阴极高频振动下加工间隙内的流场变化。分析结果表明:阴极旋转使得电解液绕流,对电解液速度、压力影响较小,而阴极高频振动使得加工区发生抽吸,加速了电解液的流动,使得加工区内电解液压力波动变化,有利于电解液的更新与电解产物的排出。     

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。     

旋转超声电解复合加工微小深孔的稳定性研究

为提高管电极旋转超声电解复合加工微小深孔的稳定性,基于ANSYS CFX,建立了气液两相流气穴模型,分析了阴极高频振动条件下不同端面间隙的流场、电场分布,仿真结果表明,大间隙有利于气泡和电解产物的排出,有利于提高加工的稳定性,但不利于孔中心的小凸台的去除。通过辅助阴极能有效减小孔中心小凸台,提高加工的稳定性。     

GH4169电解磨削加工试验研究

电解磨削是一种电解加工与机械磨削复合的加工方法,适合难加工材料复杂结构的加工。研究了GH4169电解磨削加工中阴极进给速度对材料去除率和过切量的影响,试验结果表明,随着进给速度的增大,材料去除率增大,过切量减小。通过单因素试验,得到了加工电压和电解液温度对最大进给速度及对应的材料去除率和过切量的影响规律。     

振动辅助电解车削加工技术研究

为提高电解车削材料去除率和改善加工表面质量,提出了振动辅助电解车削加工方法。采用阴极机械振动的方式使得加工间隙呈周期性变化状态,改善电解车削加工性能。进行了添加振动辅助前后的对比验证试验,研究了相关参数对振动辅助电解车削加工影响。结果表明:振动辅助电解加工能明显改善极间状态,提高材料去除率以及减小加工表面粗糙度值;材料去除率和表面粗糙度随着振动频率、加工电压、占空比、加工间隙和电解液温度呈规律性变化。     

基于MINITAB的旋转超声电解复合加工微小深孔试验研究

为解决电解加工微小深孔中电解液难以进入加工区及电解产物难以排除的问题,搭建了内喷式旋转超声电解复合加工试验装置,并基于MINITAB开展了微小深孔侧面间隙的试验研究。试验结果表明,加工电压、阴极裸露长度、进给速度和阴极转速对侧面间隙影响显著,且前两者对侧面间隙产生负效应,后两者对侧面间隙产生正效应,加工电压*进给速度、加工电压*阴极转速、加工电压*阴极裸露长度、进给速度*阴极转速对侧面间隙的交互作用显著,并得到了侧面间隙的数学回归模型,试验值与回归模型的相对误差为8.18%。在此基础上对模型进行优化,进行了响应曲面试验,并通过试验进行验证。优化结果表明,试验值与优化模型值相对误差为4.96%。通过控制阴极伸出长度能有效地减小加工孔的锥度,理论上可以将孔的锥度减小至零。所加工的微小深孔直径为4.007mm,深为67.5mm,加工电流稳定。     

喷射液束电解辅助激光加工工艺规律研究

喷射液束电解辅助激光加工是一项新型复合加工方法,将电解加工与激光加工进行复合,在加工过程中,激光束与电解液束同轴共同作用于材料表面,激光对材料的热效应和喷射电解液束对材料的电化学阳极溶解作用共同去除材料,可实现无再铸层、无微裂纹的加工效果.针对该方法,基于加工原理的分析,以加工孔锥度和材料去除率为加工质量指标,研究了激光脉冲能量、电解加工电压和加工间隙对加工质量的影响.研究结果表明,激光脉冲能量对材料去除率的影响占据主导作用;激光脉冲能量和电解加工电压的增加都会导致加工孔锥度的增大;缩短加工间隙可以提高材料去除率,但会增加加工孔入口的锥度.     

基于ANSYS设计的旋转超声加工振动装置与试验

旋转超声加工是加工陶瓷等硬脆材料的有效方式。参数化设计了旋转超声加工振动装置模型(包括夹心式压电换能器、变幅杆和工具头),运用ANSYS压电分析模块对旋转超声振动装置进行模态分析与谐响应分析。结果表明:当频率为19.8 kHz时,变幅杆小端面输出振幅最大约为19.6μm,符合旋转超声加工的要求。构建了旋转超声加工振动系统,以陶瓷材料为试验对象,进行机械磨削与旋转超声加工对比试验,加工完成后得到了加工深度与表面粗糙度参数,表明采用旋转超声加工可以得到更理想的表面粗糙度和更高的材料去除率。     

超声电解复合微细加工装置与试验研究

分析微细电解复合超声频振动加工过程机理,提出一种微细加工新方法--超声电解复合微细加工;设计、构造并完善复合微细加工装置;研究微细阴极制作工艺,利用微细组合电加工技术制作各类截面形状的微细阴极;进行超声电解复合微细加工试验,验证微细电解复合超声频振动实现微细加工的可行性及其在加工速度、精度、表面质量等方面的技术优势,探讨超声电解复合微细加工制作微结构的工艺规律。     

数控电解复合铣削不锈钢的试验研究

针对高硬度、高强度、高韧性金属材料的难加工问题,提出了数控电解复合铣削加工的方法.该方法利用复合阴极相对工件作数控展成运动,可完成对复杂形状工件的电解复合铣削加工.在成功研制复合阴极、特殊刀柄、新回转工作台、电解液防护槽、排水和排气管路基础上,将一台数控高速雕铣机床改造成为一台数控电解复合铣削加工机床.选取主轴转速、进给速度、电压、电解液压力及切深为5个主要工艺参数,对304不锈钢进行了数控电解复合铣削正交试验研究,最终得到了加工该材料的较优的工艺参数.     

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。     

Study of electrochemical machining characteristics of Al/SiCp composites

Non-conventional machining is increasing in importance due to some of the specific advantages which can be exploited during machining operation. Electrochemical machining (ECM) appears to be a promising technique, since in many areas of application, it offers several special advantages including higher machining rate, better precision and control, and a wider range of materials that can be machined. The present work is, therefore, initiated to investigate the influence of some predominant electrochemical process parameters such as applied voltage, electrolyte concentration, electrolyte flow rate and tool feed rate on the metal removal rate (MRR), and surface roughness (Ra) to fulfill the effective utilization of electrochemical machining of LM25 Al/10%SiC composites produced through stir casting. The contour plots are generated to study the effect of process parameters as well as their interactions. The process parameters are optimized based on Response Surface Methodology (RSM).     

Flow field design and experimental investigation of electrochemical machining on blisk cascade passage

Electrochemical machining (ECM) provides an economical and effective way for machining heat-resistant, high-strength materials into complex shapes that are difficult to machine using conventional methods. It has been applied in several industries, especially aerospace, to manufacture blisk. The electrolyte flow field is a critical factor in ECM process stability and precision. To improve the process stability and the efficiency of blisk cascade passages, ECM with a radial feeding electrode, a rational electrolyte flow mode for electrochemical machining called “Π shape flow mode”, is discussed in the paper. Three flow field models are described separately in this report: traditional lateral flow mode, positive flow mode and Π-shaped flow mode, and the electrolyte velocity and pressure distribution vectors for each flow mode are calculated by means of a finite element fluid analysis method. The simulation results show that the electrolyte flow is more uniform with the Π-shaped flow mode. The deformation of the cathode, which is caused by the pressure difference, is also analysed in this report. The cascade passage ECM with a radial feeding electrode was experimentally tested out to evaluate the rationality of the flow field, and the fluctuation of current during the process was less than 1 %, which means that the process that uses the Π-shaped flow mode is stable. The feeding velocity of the cathode with the Π-shaped flow mode is approximately 70 % higher than that with the other two flow modes, and the incidences of short circuiting are obviously decreased. The surface roughness of the blisk hub is only 0.15 μm, and the machining error of the hub is less than 0.1 mm. The results demonstrate that using the Π-shaped flow mode can enhance the quality, stability and efficiency of blisk cascade passage ECM.     

Optimal design of the sheet cathode using W-shaped electrolyte flow mode in ECM

Electrochemical machining (ECM) is an important non-conventional manufacture technology for machining workpieces with complex and thin structures. In this study, ECM is used to machine the blisk. Because the channel between two blades is narrow, the cathode must use the thin-sheet structure. In the ECM process, the cathode will bear electrolyte pressure which can cause deformation. The cathode deformation has negative influence on the machining quality and process stability. To minimize the deformation, the optimization treatment of the cathode thickness is carried out and a new electrolyte flow mode, W-shaped flow mode, is adopted to weaken the pressure. The corresponding computer simulation is applied, and the results show that the cathode deformation decreases by 17.6% and 28% by taking the above-mentioned two measures. It indicates that the new thin-sheet cathode presented in this paper is useful and the new flow mode is effective in ECM. Furthermore, the experiments are conducted using the optimal thickness electrode and W-shaped flow mode to verify the machining effects. Then the corresponding experiment is carried out, and the result shows that the optimal treatments to reduce the cathode deformation have remarkable effects.     

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.     

渐开线内花键电解加工流场设计及工艺稳定性研究

为进一步提高渐开线内花键电解加工的工艺稳定性,基于数值分析方法探讨了电解液流动方式、工具阴极结构、电解液参数对流场分布的影响规律。数值分析结果表明：电解液侧向流动可以改善加工区入口处电解液流速分布均匀性;带有导流段的变截面阴极能够降低工件表面流速波动。针对工艺稳定性及加工定域性,开展了渐开线内花键电解加工试验研究。试验结果表明：进给速度可达2.1 mm/min以上,齿形误差可控制在0.015 mm以内,当加工深度为30 mm时,齿向误差在0.02 mm以内。该加工方式的效率及精度能够满足很多实际需求,具有明显的技术经济优势。     

Cutting tool wear monitoring for reliability analysis using proportional hazards model

Electrochemical machining (ECM) is an important technology in machining difficult-to-cut materials and to shape free-form surfaces. In ECM, material is removed by electrochemical dissolution process, so part is machined without inducing residual stress and without tool wear. To improve technological factors in electrochemical machining, introduction of electrode tool ultrasonic vibration is justifiable. This method is called as ultrasonically assisted electrochemical machining (USAECM). In the first part of the paper, the analysis of electrolyte flow through the gap during USAECM has been presented. Based on computational fluid dynamic methods, multiphase, turbulent and unsteady electrolyte flow between anode and cathode (under assumption that cavitation phenomenon occurs) has been analysed. Discussion of the obtained solutions is the base to define optimal conditions of electrolyte flow in case of USAECM process. The second part of the paper is connected with experimental investigations of USAECM process. Classic experimental verification of obtained results in case of machining is extremely difficult, but influence of the ultrasonic vibration can be observed indirectly by changes in technological factors (in comparison to machining without ultrasonic intensification), whereas results of numerical simulation give possibility to understand reason and direction of technological factors changes. Investigations proved that ultrasonic vibrations change conditions of electrochemical dissolution and for optimal amplitude of vibration gives possibility to decrease the electrode polarisation.     

Utilization of flow field simulations for cathode design in electrochemical machining of aerospace engine blisk channels

Electrochemical machining (ECM) cathode flow field design is crucial to machining aerospace engine blisk channels. In order to reduce the cathode design cycle and cost in machining, 3D cathodes and flow field simulation model were developed to facilitate analysis the flow fields in reversed flow patterns. The electrolyte flow line was determined by the distributions of electrolyte pressure, the diameter of the back orifice, and the areas of the back orifices in locations A, B, and C. The simulation results were utilized to analyze the influence of the electrolyte flow line. To verify the accuracy of the simulation, the experiments were carried out. The simulation results were consistent with the experiment data. It indicates that electrolyte flow field simulation is an effective method to optimize cathode design. Utilizing this methodology can improve the ECM cathode design efficiency and reduce cathode revision time.     

Experimental study of rotary magnetic field-assisted dry EDM with ultrasonic vibration of workpiece

Dry electrical discharge machining (EDM) is a green machining method which replaces the gas instead of liquid as dielectric medium. Due to the environmentally friendly nature of this method, recently, researchers focused on characterization of this process. In this work, effects of rotary magnetic field and also ultrasonic vibration of workpiece were studied on dry EDM process performance. Conducted experiments were divided in two main stages. At first stage, preliminary experiments were carried out to determine the best tool design in material and geometry points of view by considering the material removal rate (MRR). Also, effect of magnetic field was studied in the first stage. Results of the first stage of experiments indicated that the brass tool with two eccentric holes has the highest MRR rather than the other existing tool. In the second stage of experiments, parametric study on dry EDM process were implemented by using a brass tool with two eccentric holes and by applying rotary magnetic field for all experiments of the second stage. Influences of parameters such as pulse current, pulse on-time, pulse off-time, tool rotational speed, air injection inlet pressure, and especially power of ultrasonic table were studied on MRR, surface roughness (SR), electrode wear rate (EWR), and overcut (OC). Results showed that magnetic field has positive effects on MRR and SR. Also, by application of ultrasonic vibration achieving to superior MRR is feasible. At the end of the work, mathematical models were developed to correlate a relationship between process inputs and main outputs.