高效精密绿色数控电火花成型关键技术研究及应用

发布时间：2019-01-27 19:20

【摘要】：针对电火花成型加工提高效率、精度和环境友好性的问题,论文聚焦高效驱动、精密成型、绿色加工三个技术方向,通过直线驱动的配重扰动抑制、电极损耗的预变形精密补偿、水幕机罩的绿色净化和集成平台等关键技术及应用的研究,提高成型机的综合加工性能,实现数控电火花的高效精密绿色成型。在分析课题背景和研究意义后,论文提炼了当前国内外对几个关键技术的研究现状和不足,并提出本文所研究的关键技术点。研究了面向高效驱动的配重扰动补偿技术。针对传统驱动方式的不足,设计了主轴的直线驱动结构。面对配重系统在高速驱动中引起的扰动问题,提出了实时精密补偿技术。分析了配重平衡力波动和配重摩擦力波动这两个引起主轴振动的主要因素,利用等熵一元绝热气流模型和改进的Stribeck模型,分别建立平衡力波动和摩擦力波动模型,并通过扰动量的等效动态补偿,结合双PID解耦和模糊PID控制,有效抑制了主轴的振动,提高了主轴的位置控制精度和反馈速度。仿真和实验对比结果表明,采用配重扰动补偿控制技术的直线电机立式驱动,速度跟踪响应快,不仅极大抑制了主轴在高低速和变向驱动时呈现的爬行和抖振现象,而且超调也得到了明显的改善,减少了主轴的位置误差,实现主轴的高效驱动。研究了面向精密成型的电极损耗预变形补偿技术。针对电火花加工中,电极的损耗带来加工精度下降的不足,提出了基于预变形的电极补偿技术,实现了一个电极完成全程精密成型,避免了电极更换,提高了加工精度和加工效率。按不同工况,研究了不同的预变形技术:在微细损耗工况下,提出了曲率偏置补偿技术;在大损耗量工况下,提出了基于放电间隙的分层补偿技术。仿真和实验对提出的补偿技术进行了验证,结果表明成型零件的几何平均误差达到了电火花精密成型标准。研究了面向绿色加工的水幕式气雾净化技术.分析了放电加工中电离气雾产生和扩散的机理,从减少对主轴系统的精度影响和提高环境友好性出发,设计了水幕式净化机罩。构建了基于附壁理论的水幕形成模型,利用初级破碎理论建立水幕连续性方程模型,系统分析了射流从出口到水幕形成的全过程。以射流速度、入射角、附壁长度和附壁倾角作为四个典型因素,分析对附壁形成难易程度、水幕长度和水幕质量的影响。设计了固结与主轴的净化机罩和循环净化技术,实现电火花的绿色成型加工。关键技术集成应用平台研发。以关键技术的集成应用研发为主线,把高效驱动技术,精密成型技术和绿色净化技术集成到样机上,并进行了设计和开发,通过实验验证电火花成型加工的综合性能。最后,论文总结了研究内容、本文的主要创新点,分析了电火花成型加工未来的发展,给出了今后的进一步研究方向。
[Abstract]:Aiming at the problems of improving efficiency, precision and environmental friendliness in EDM, the paper focuses on three technical directions of high efficiency driving, precision forming and green machining, which is restrained by the counterweight disturbance of linear drive. The research on the key technologies and applications such as the precision compensation of electrode loss, the green purification of the water screen hood and the integrated platform can improve the comprehensive processing performance of the molding machine and realize the high efficiency and precision green forming of the NC EDM. After analyzing the background and significance of the research, the paper abstracts the current research status and deficiency of several key technologies at home and abroad, and puts forward the key technical points of this paper. The counterweight disturbance compensation technology for high efficiency drive is studied. Aiming at the shortage of traditional drive mode, the linear drive structure of spindle is designed. In the face of disturbance caused by high speed drive of counterweight system, a real-time precision compensation technique is proposed. In this paper, two main factors that cause the vibration of spindle are analyzed, which are the fluctuation of balance force and friction force of counterweight. The equilibrium force fluctuation and friction fluctuation model are established by using the isentropic univariate adiabatic airflow model and the improved Stribeck model, respectively. Through the equivalent dynamic compensation of the disturbance quantity, combined with double PID decoupling and fuzzy PID control, the vibration of the spindle is effectively suppressed, and the position control accuracy and feedback speed of the spindle are improved. The results of simulation and experiment show that the vertical drive of linear motor with counterweight disturbance compensation technology has fast velocity tracking response, which not only greatly restrains the crawling and buffeting phenomenon of spindle in high and low speed and variable direction drive. The overshoot is improved obviously, the position error of the spindle is reduced, and the high efficiency drive of the spindle is realized. The predeformation compensation technology of electrode loss for precision molding was studied. In order to reduce the machining precision due to the loss of electrode in EDM, an electrode compensation technology based on pre-deformation is put forward, which realizes the complete precision molding of one electrode and avoids the replacement of electrode. The machining precision and efficiency are improved. According to different working conditions, different pre-deformation technologies are studied: in the case of micro-loss, the curvature offset compensation technology is proposed, and the layered compensation technology based on discharge gap is proposed under the condition of large loss. The simulation and experimental results show that the geometric average error of the formed parts is up to the standard of EDM precision molding. The water curtain air mist purification technology for green processing was studied. The mechanism of ionization mist generation and diffusion in discharge machining is analyzed. In order to reduce the influence on the precision of the spindle system and improve the environmental friendliness, the water curtain cleaning machine hood is designed. The water curtain formation model based on the theory of wall attachment is constructed, and the continuity equation model of water curtain is established by using the primary breaking theory. The whole process of jet formation from outlet to water curtain formation is systematically analyzed. Four typical factors, such as jet velocity, incident angle, wall attachment length and wall inclination angle, are used to analyze the influence of jet velocity, incident angle, water curtain length and water curtain quality on the difficulty of wall attachment. The cleaning machine cover and circulating purification technology of consolidation and spindle are designed to realize green forming of EDM. Research and development of key technology integration application platform. Based on the research and development of integrated application of key technology, the high efficiency driving technology, precision forming technology and green purification technology are integrated into the prototype, and the design and development are carried out, and the comprehensive performance of EDM is verified by experiments. Finally, the paper summarizes the research content, the main innovation of this paper, analyzes the future development of EDM, and gives the future research direction.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG661

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