微小孔电火花—电解复合加工穿透检测及实验研究

发布时间：2018-05-16 21:19

本文选题：电火花-电解复合加工 + 微小孔　；参考：《南京航空航天大学》2016年硕士论文

【摘要】：微小孔电火花-电解复合加工将电火花加工和电解加工相结合,在加工中同步复合电火花高速穿孔和电化学溶解作用,兼具两者在小孔加工时的优势,具有较高的加工效率和较好的加工精度,并有望实现无重铸层加工的要求,未来将适合航空发动机涡轮叶片气膜冷却孔的加工需求。涡轮叶片是一种中空零件,其内部是复杂的流道结构,流道宽度只有数毫米,表面设计有大量气膜孔与流道连通。当采用电火花-电解复合加工进行气膜冷却孔的加工时,如不能及时检测工具电极的穿透以停止其进给,很可能造成对内部流道结构和另一侧壁面的误加工,使叶片报废。因此进行复合加工的穿透检测研究是很有必要的。本文开展了微小孔电火花-电解复合加工穿透检测及试验研究。具体研究了电火花-电解复合加工穿透检测的判断原理,得到了基于加工电压和电流的穿透检测判据,并基于数据采集卡、计算机和LabVIEW软件搭建了复合加工的穿透检测平台,在平台上进行了复合加工穿透检测试验,试验表明平台具有很高的检测成功率,并评价了平台参数对小孔加工质量的影响。论文主要研究内容如下:(1)提出了电火花-电解复合加工穿透检测的判据。针对微小孔电火花-电解复合加工内冲液式、浸液与电极旋转相结合式以及外冲液辅助式三种冲液形式进行了流场的有限元仿真,结果表明内冲液式最适合于电火花-电解复合加工。在此基础上进一步对内冲液式复合加工进行了加工电压电流的波形试验,在比较了复合加工电火花效应和电解效应的不同波形表现后,分析了工件底部未涂覆和涂覆绝缘反衬层两种情况下复合加工穿透三个阶段(穿透前、穿透瞬间、穿透后)的不同电火花效应和电解效应,提出了基于加工电压和电流的穿透检测的判断准则。(2)搭建了电火花-电解复合加工穿透检测平台。该穿透检测平台由硬件平台和软件组成,其中硬件平台基于数据采集卡和计算机构建,软件通过LabVIEW编写。平台可实现加工电压电流的数据采集、穿透状态分析判断、穿透信号输出控制机床主轴停止进给三个部分的功能,并基于LabVIEW编程实现上述功能。平台的结构和设计简单,且正常实现了穿透检测功能。(3)进行了电火花-电解复合加工穿透检测试验研究。本文在搭建的穿透检测平台上,分别针对工件底部未涂覆和涂覆绝缘反衬层两种情况,开展了穿透检测试验,试验评价了两种情况下的穿透检测成功率,结果表明该平台具有良好的检测成功率,并分别评价了平台穿透延时和底部停顿时间两个参数对穿出距离、小孔锥度、孔型以及重铸层的影响,对参数进行了优选。试验最后分析了工件底部涂覆有绝缘反衬层时,有无穿透检测对小孔复合加工孔口形貌及重铸层残留的影响,说明穿透检测对提高复合加工加工稳定性和加工质量具有积极的作用。
[Abstract]:Micro hole EDM and ECM combine EDM with ECM. In machining, synchronous EDM high speed perforation and electrochemical dissolution have the advantages of both in small hole machining. It has higher machining efficiency and better machining precision, and it is expected to meet the requirements of non-cast layer machining, which will be suitable for the processing of air-engine turbine blade gas film cooling holes in the future. Turbine blade is a hollow part with a complex flow channel structure with a width of only a few millimeters and a large number of air film holes connected to the runner. When the gas film cooling hole is processed by EDM, if the penetration of the tool electrode can not be detected in time to stop its feed, it may lead to the wrong machining of the internal runner structure and the other side wall, which will lead to the blade scrapping. Therefore, it is necessary to study the penetration detection of composite machining. In this paper, the penetration detection and experimental study of micro-hole EDM-ECM are carried out. The judgment principle of EDM penetration detection is studied in detail, and the penetration detection criterion based on machining voltage and current is obtained. Based on data acquisition card, computer and LabVIEW software, the penetration detection platform of composite machining is built. The penetration test of composite machining on the platform shows that the platform has a high success rate of detection and the influence of platform parameters on the machining quality of small holes is evaluated. The main contents of this paper are as follows: (1) the criterion of EDM penetration detection is proposed. In this paper, the finite element simulation of flow field is carried out for the three kinds of internal efflux, the combination of immersion and electrode rotation, and the external flushing assistant in micro hole EDM combined with electrolytic machining, in which the flow field is simulated by finite element method. The results show that the internal efflux type is the most suitable for EDM-ECM. On the basis of this, the waveform test of voltage and current was carried out on the internal flushing composite machining, and the different waveforms of EDM and electrolytic effect were compared. The different EDM effect and electrolysis effect in the three stages of composite machining penetration (before penetration, penetration moment and after penetration) are analyzed in the case of uncoated and coated insulating backliner on the bottom of workpiece. The judgement criterion of penetration detection based on machining voltage and current is put forward. (2) the platform of EDM penetration detection based on EDM is built. The platform is composed of hardware platform and software. The hardware platform is based on data acquisition card and computer, and the software is written by LabVIEW. The platform can realize the functions of data acquisition of processing voltage and current, analysis and judgement of penetration state, and output of penetration signal to control the spindle of machine tool to stop feeding. The above functions can be realized by programming based on LabVIEW. The structure and design of the platform are simple, and the penetration detection function is realized normally. In this paper, the penetration test is carried out on the platform, which is not coated on the bottom of the workpiece, and the success rate of the penetration detection is evaluated under the two conditions. The results show that the platform has a good success rate of detection, and the influence of the penetration delay and the bottom pause time on the penetration distance, the taper of the hole, the hole shape and the recast layer are evaluated, and the parameters are selected. At the end of the experiment, the influence of penetration detection on the morphology of the hole and the residual of the recast layer is analyzed when the insulating liner is coated on the bottom of the workpiece. It shows that penetration detection has a positive effect on improving the stability and quality of composite machining.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG666

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