整体式蜂窝阵列孔电解加工试验研究

针对整体式蜂窝阵列孔电解加工过程中孔壁尺寸控制难题,以壁厚沿孔轴线变化的阵列蜂窝孔为研究对象,对蜂窝孔壁电解成形壁厚尺寸控制进行电场和流场仿真。结果表明：改变阴极加工刃结构、进给速度参数等措施能有效调控侧面加工间隙,进而控制壁厚成形尺寸;附加阴极振动能够改善加工间隙流场,从而提高壁厚成形尺寸一致性。基于仿真优化结果开展整体式蜂窝阵列孔电解加工试验,可控制蜂窝孔壁成形精度在±0.04 mm。     

异形深孔电解加工过程的流场优化

针对异形深孔电解加工过程中进出口流场突变现象、加工间隙流场分布不均、工艺稳定性相对较差等问题,以深径比12∶1的异形孔零件为研究对象,对加工开始、加工稳定、加工穿透各个阶段流场分布进行仿真优化研究。通过导流结构、多孔通液阴极结构保证电解加工进出口流场平稳性;采用合理的电解液压力、复合进给加工模式等措施改善流场分布均匀性,避免空穴现象。基于流场仿真优化结果,开展了异形深孔连续电解加工试验,孔尺寸精度可控制在0.03 mm。     

管电极电解加工三角孔实验研究

管电极电解加工作为一种采用中空金属管作为工具阴极,对阳极工件进行溶解去除的加工技术,在加工异形孔方面具有独特的优势。以异形孔中的三角孔作为加工对象,研究了初始加工间隙、进给速度及电压等因素对电解加工精度的影响。结果表明:减小初始加工间隙、提高进给速度及降低电压可显著降低三角孔侧壁的锥度,并提高电解加工精度。研究结果对三角孔及异形孔的高精度、高效率加工具有一定的指导意义。     

脉冲电解加工小孔的试验研究

介绍在耐高温镍基合金上进行脉冲电解加工小孔的试验研究.分析了加工过程中脉冲宽度、脉冲间隔、工具电极进给速度对小孔加工的精度影响.结果表明:采用较小的电参数和较大的工具电极进给速度,有利于减小小孔的侧面加工间隙,提高孔的加工精度.     

低频振动小孔径内壁面微结构电解加工技术研究

为了研究低频振动电解加工对小孔径内壁面加工的影响,采用数值模拟和实验相结合的方法进行电解加工,分析影响加工结果的工艺参数及低频振动对小孔径内壁面加工精度的影响。结果表明:采用阴极低频振动加工小孔径内壁面,有利于加工间隙内电解液的循环更新和电解产物、电解热的排除,提高加工精度,改善加工定域性,同时也延长了工具电极的寿命。     

混气-定间隙间歇进给电解加工技术研究

以航天姿/轨控发动机拉瓦尔式小喷管为研究对象,采用常规直流电解加工、定间隙间歇进给电解加工、混气-定间隙间歇进给电解加工等技术,研究提高拉瓦尔式小喷管内型面加工精度以及表面质量的工艺方法.试验结果表明,混气-定间隙间歇进给电解加工技术具有复制精度高、加工表面质量好、加工间隙均匀,工具阴极基本不做修正,就能得到良好的加工效果.     

多阶内锥孔液力自驱动旋转磁场辅助电解加工

针对电解加工多阶内锥孔类零件表面质量差的问题,提出了液力自驱动旋转磁场辅助电解加工方法,建立液力自驱动旋转流场模型并进行流场仿真,结果表明：当阴极叶片为3片、叶片厚度为0.8 mm、电解液流速不低于5 m/s时,阴极芯轴尾部叶轮可实现稳定旋转。在此基础上,设计了液力自驱动旋转磁场辅助电解加工阴极,在加工电压10 V、电解液温度30℃、电解液压力1.6 MPa、阴极进给速度5 mm/min时,利用复合电解液进行添加旋转磁场和不加磁场的多阶内锥孔电解加工工艺对比试验,结果显示：在相同加工参数下,添加旋转磁场加工的工件表面粗糙度值为Ra0.437μm,较无磁场大幅降低。     

方形阴极数控电解加工工艺试验研究

采用4种不同方案的方形阴极进行电解加工工艺试验,并对正交试验结果进行极差分析,得到工作电压、阴极进给速度、电解液压力、初始间隙对切削深度的关系曲线.通过比较4种不同方案阴极对切削深度的影响,得出最优的阴极结构.在此基础上,选取合适的工艺参数组合,进行方孔的电解加工试验.     

基于COMSOL闭式整体构件流道电解加工流场的仿真

提高闭式整体构件气流通道数控电解/电火花组合加工效率的关键是提高其粗加工工序电解加工的效率,可尝试采用开槽、拷形一次完成的方案。由于气流通道深、窄、弯曲,首先必须面对的是电解加工间隙流场分布极不均匀的问题,通过改变阴极结构、回液孔分布及供液方式的设计,基于COMSOL对上述不同阴极进行电解加工间隙流场的仿真、比较,改善了间隙流场分布。分析表明,当进口压力为0.8 MPa,十字交叉槽槽宽为1.5 mm,锥头回液孔数量为12个,三排错开排放,间隙流场较均匀。     

涡轮叶片气膜冷却孔电解加工气液两相流场特性分析

以高温镍基合金Inconel718为基材进行气膜冷却孔电解加工基础试验,在电解加工过程中,阴极反应界面析出氢气,导致电解液的电导率不再是一个常数,从而影响冷却孔的加工成型精度。结合前期基础试验,建立冷却孔电解加工流道二维模型,基于COMSOL Multiphysics软件对冷却孔端面间隙内气液两相流场进行仿真,研究加工电压、电解液入口压力及管电极进给速度对氢气析出量的影响,并定性地分析电解加工过程中气泡率与电导率之间的关系。由仿真结果可知:氢气的体积分数随加工电压和电极进给速度的增大而增大,随电解液入口压力的增大而减小,且氢气体积分数越大,电解液的电导率越小。     

超声辅助电解磨削GH625微小孔工艺研究

超声振动辅助电解磨削加工技术是一种以超声振动作为辅助、电解磨削为主要加工方式实现零件精加工的新型加工技术.为获得更高表面质量的管电极微孔,首先利用单因素法对GH625材料进行管电极打孔,初步得到最小平均锥度0.043°的微小孔,然后通过正交试验研究脉冲电压、电解液浓度、主轴进给速度、阴极转速对加工微小孔锥度和表面质量的...     

Precision machining of small holes by the hybrid process of electrochemical removal and grinding

This paper presents a hybrid process of grinding and electrochemical removal for machining of precision small holes with hard-to-machine materials. In the process, a metal rod with coated abrasives as cathode tool rotates at high speed and removes material electrochemically and mechanically for a pre-machined pilot hole. The effects of process parameters on the hole surface quality and dimensional accuracy were demonstrated experimentally. Material removals on grinding and electrochemical machining are well balanced by rationally determining machining voltage, tool rotation speed and feed rate. Precision holes of diameters down to 0.6 mm with sharp edges and without burrs have been produced.     

MA956高温合金活动模板电解加工小孔技术研究

对采用活动模板电解加工技术在MA956铁基高温合金薄板上加工小孔的工艺方法进行了讨论。研究了电解液温度、加工电压、电源占空比和脉冲频率等参数对小孔加工结果的影响。研究表明:采用10%w.t.NaNO_3电解液,在电解液温度为30℃、加工电压为40 V、电源占空比为30%、电源脉冲频率为400 Hz时,能在MA956高温合金薄板上加工获得锥度小的小孔。     

Electrochemical drilling with vacuum extraction of electrolyte

Forward flow pattern of electrolyte is widely used in electrochemical drilling (ECD) process. But electrolyte in the machining gap presents a sharp divergent flow which causes an abnormal dissolution and even harmful sparking. Reverse flow of electrolyte leads to a stable machining process but is rarely used due to the poor application feasibility. In this paper, an electrochemical drilling method with vacuum extraction of electrolyte has been proposed. Vacuum extraction of electrolyte greatly facilitates the application of reverse flow in electrochemical drilling. Flow distributions along the machining gap with different electrolyte flow pattern are compared numerically and experimentally. Reverse flow using vacuum extraction is shown to improve the process stability while diminishing sparking and formation of striations. Machining characteristics of vacuum extraction are investigated experimentally. To minimize the radial overcut of machined hole by electrochemical machining with vacuum extraction of electrolyte, the orthogonal design is used to optimize process parameters such as initial machining gap, applied voltage, tool feed rate, and electrolyte concentration. Good results have been obtained in the experiments with optimized parameters.     

绝缘涂层构件电化学放电穿孔技术

研究了绝缘涂层构件的电化学放电加工原理与5种放电过程及其电压电流波形特点。分析了绝缘涂层构件穿孔技术中的绝缘涂层材料加工、绝缘涂层与基体金属过渡加工及基体金属加工3种不同状态及其特点,采用不同的进给速度和加工电压,以提高加工效率和质量。对钛合金基体的氧化锆陶瓷涂层材料进行了电化学放电穿孔实验,验证了该方法是可行的。     

钛合金小孔电火花快速加工试验研究

采用电火花高速小孔机,在2 mm厚的TC4钛合金板上,进行直径为0.5 mm小孔的快速加工试验研究。运用正交试验法,研究电火花加工电参数(峰值电流、脉宽、脉间和电容)对加工效率和小孔锥度的影响,并对试验结果进行方差分析和灰关联分析,得出最优加工参数。结果表明,经参数优化后,在小孔深度方向的加工效率为3.46 mm/min,小孔锥度减小18.51%,满足钛合金件高速、精密加工的技术要求。     

Tube electrode high-speed electrochemical discharge drilling using low-conductivity salt solution

Film cooling holes are widely used in the aerospace industry, and their fabrication requires high machining speed and accuracy, as well as good surface quality. Tube electrode high-speed electrochemical discharge drilling (TSECDD) is a promising hybrid machining method for the fabrication of film cooling holes in difficult-to-machine superalloys. An electrochemical reaction can occur if a low-conductivity salt solution is used in the drilling. Materials can also be removed at a high speed using electrical discharge machining (EDM). Thus, TSECDD and electrochemical machining (ECM) can be combined into a unique machining process using a low-conductivity salt solution. This machining process achieves both a high machining speed and good surface finish. In this study, the material removal mechanism of TSECDD was studied using a low-conductivity salt solution, and comparisons with high-speed electrical discharge drilling were made. The performance of the process was investigated using salt solutions of various conductivities. The results show that there are different material removal mechanisms in the frontal gap and the lateral gap and that, in the latter, there is a transition from EDM to ECM. Experiments conducted using TSECDD confirm that the use of this process with a low-conductivity salt solution can improve the machining surface and machining efficiency achieved. The results also show that the use of a low-conductivity solution improves the material removal rate, the hole diameter, and the taper angle.     

数控电解机械复合刃口钝化的实验研究

电解机械复合加工方法进行硬质合金刀具的刃口钝化,可以提高刀具钝化后的刃口均匀性。重点研究了电化学机械复合加工的刃口钝化工艺,通过对电解电压、电解间隙、进给量以及电源频率试验参数进行正交试验,找到了较优的钝化工艺参数。试验表明：影响刃口去除量的最大因素是电解间隙,其次是电解电压;最优的工艺参数组合：电解电压12     

Shaped tube electrochemical drilling of good quality holes

This paper is concerned with the shaped tube electrochemical drilling (STED) of small diameter cooling holes in turbine blades. Following an initial identification of the common defects occurring in STED, a partial factorial design of experiments (DOE) was carried out to identify the more important process parameters that affect hole quality. For these process parameters, a full factorial design of experiments was conducted to study their effects not only on hole diameter but also on hole taper. Guidelines and equations for determining appropriate operating conditions to drill a good quality hole are presented for one drill diameter.