电火花模糊抬刀控制研究

发布时间：2018-03-01 08:02

  本文关键词： 电火花排屑 极间流体仿真 模糊抬刀控制 抬刀参数优化　出处：《哈尔滨工业大学》2016年硕士论文　论文类型：学位论文

【摘要】：随着国际加工制造业地发展,机械产品变地小型化,精密化。电火花加工技术作为一种特种加工方法,以其非接触,高精度的加工特点成为机械制造领域的重要方法之一。由于电火花加工过程处在一个相对密闭的环境中,加工产生的金属废屑难以排除,严重影响到正常加工的进行。抬刀排屑作为一种独立于电火花放电过程的排屑方式,通过介质的流动带动废屑粒子从加工间隙中流出。为了深入研究抬刀动作对排屑的影响,本文利用Ansys Fluent有限元仿真软件建立了抬刀流体仿真模型,定性分析了煤油介质的流动形式;通过离散相技术,定量分析了不同抬刀参数下极间废屑粒子的排出量。为了满足快速抬刀和微动进给的运动精度要求,加入了双PID运动参数切换。在自主设计开发的数控平台上进行了不同抬刀参数下小孔加工工艺实验,讨论了抬刀参数对加工效果的影响。为了提高电火花放电稳定性和加工效率,本文设计出模糊抬刀方案,将原本开环抬刀方式,通过加入模糊控制器设计成一个闭环伺服系统。在MATLAB中利用专用工具包设计搭建模糊抬刀控制器,利用前期抬刀流体仿真结果和开环抬刀实验结果总结抬刀规律,设计模糊数据库,完成控制器仿真。通过串口通信技术,将实时采集到的极间电压反馈给上位机。上位机通过运算,将得到的电压偏差值及偏差变化率作为控制器输入,将抬刀高度和抬刀周期作为输出,完成闭环伺服系统。利用C++语言编写开环抬刀功能模块和模糊抬刀功能模块,并嵌入到数控系统中。最后,设计开环抬刀和闭环抬刀对比工艺实验,验证模糊抬刀控制器的有效性。与传统定时定速定高抬刀方法相比,模糊抬刀方案通过判断电火花极间放电状态,实现抬刀参数实时优化,提高了排屑效率,保证了极间放电的稳定性,高效性。
[Abstract]:With the development of international manufacturing industry, mechanical products become miniaturized and refined. As a special processing method, EDM is non-contact. The characteristics of high precision machining have become one of the important methods in the field of mechanical manufacturing. Because the process of EDM is in a relatively closed environment, it is difficult to eliminate the metal scrap produced by machining. As a way of chip removal independent of the electric spark discharge process, the debris removal from the machining gap is driven by the flow of the medium. In order to study the influence of the lifting knife action on the chip removal, In this paper, Ansys Fluent finite element simulation software is used to establish the fluid simulation model of lifting tool, and the flow form of kerosene medium is qualitatively analyzed. In order to satisfy the requirement of moving precision of quick lifting knife and fretting feed, the quantity of debris particles discharged between poles under different lifting tool parameters was quantitatively analyzed. With the addition of double PID motion parameter switching, the machining process of small hole under different lifting parameters was carried out on the NC platform designed and developed by ourselves. In order to improve the stability of electric spark discharge and the machining efficiency, a fuzzy lifting tool scheme was designed, in which the original open-loop lifting method was used. A closed loop servo system is designed by adding fuzzy controller. In MATLAB, a special tool kit is used to design and build a fuzzy lifting tool controller. The rule of lifting knife is summarized by using the simulation results of pre-lifting fluid and the experimental results of open-loop lifting tool. The fuzzy database is designed and the controller simulation is completed. Through serial port communication technology, the voltage between poles collected in real time is fed back to the host computer. Through operation, the voltage deviation value and the variation rate of the voltage deviation obtained by the upper computer are taken as the input of the controller. The closed loop servo system is completed by taking the height and cycle of the lifting tool as the output. The function module of open loop lifting cutter and fuzzy lifting tool module are programmed by C language and embedded in the NC system. Finally, The experiment of contrasting open loop and closed loop lifting tool is designed to verify the effectiveness of fuzzy lifting tool controller. Compared with the traditional method of fixed speed and fixed height lifting tool, the fuzzy lifting tool scheme judges the discharge state between the electrodes of electric spark. The parameters of lifting tool are optimized in real time, the chip removal efficiency is improved, and the stability and efficiency of inter-pole discharge are ensured.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG661

【参考文献】

中国硕士学位论文全文数据库 前1条

1 杨青照;电火花加工抬刀的自适应控制研究[D];北京建筑大学;2014年

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