【作者】 李小朋；

【导师】 刘永红；

【作者基本信息】 中国石油大学 ， 机械设计及理论， 2007， 博士

【摘要】 为了解决非导电工程陶瓷的高效精密加工问题，综合考虑电火花加工和机械磨削的优点，创造性地提出了非导电工程陶瓷双电极同步伺服电火花机械复合磨削新工艺。其原理就是加工时导电磨轮与薄片电极分别与脉冲电源的正、负极相连，薄片电极在伺服机构的带动下紧贴工件表面向磨轮作伺服送进，使薄片电极的前端与磨轮紧贴工件表面形成火花放电通道，由放电通道产生的瞬时高温、高压等作用来蚀除工件，同时在工件上形成一层变质层，该变质层由磨轮的机械磨削作用去除。该加工技术具有生产率高、成本低、对环境无污染等优点。设计出了非导电工程陶瓷双电极同步伺服电火花磨削机床，详细介绍了薄片电极伺服进给机构等关键部件的结构组成和设计原理。薄片电极伺服进给机构具有恒张力自动送带与退带功能，可以保持稳定的放电间隙，使加工过程稳定持续地进行。针对该加工技术的特殊要求和传统电阻限流脉冲电源电能利用率低等问题，采用新型拓扑结构和控制策略研制出了调压式节能脉冲电源。该电源具有自适应调压、等电流脉宽及独立电气特性，取消了耗能严重的限流电阻，可提高电能利用率2倍左右，且减小了电源体积。采用带反馈的脉宽调制技术，研制出了片电极伺服机构直流电机控制系统，可使电火花加工过程稳定持续地进行。利用三相交-直-交变频调速与计算机控制技术，研制出了磨轮主轴的交流变频调速控制系统。对非导电工程陶瓷电火花磨削特性和工艺规律进行了实验研究，给出了电源的脉宽、脉间、峰值电压、峰值电流、进给速度、磨轮转速和工作液等对材料去除率和加工表面质量的影响规律关系。设计了非导电工程陶瓷单脉冲尖电极放电蚀除实验装置，研究了单脉冲放电的材料蚀除机理，总结出了相应的规律关系。更多还原

【Abstract】 A novel technique named double electrodes synchronous servo electrical discharge grinding (DESSEDG) for non-conductive engineering ceramics, which can integrate the advantages of electrical discharge machining (EDM) and grinding, is presented to achieve high efficiency precision machining. This method employs a conductive grinding wheel which rotates fast on the surface of workpiece, and a sheet electrode which is automatically fed to the place where the wheel and workpiece meet. Discharges happen between wheel and sheet electrode under pulse power supply. The sheet electrode is very thin, so it can be considered that discharges are just on the surface of workpiece. The high temperature and pressure of plasma channel can be directly exerted to the workpiece surface to remove material. Then the sparks eroded layer is machined a second time by grinding of the conductive wheel. The advantages of DESSEDG are high efficiency, low processing costs, environmental pollution-free, and so on.The DESSEDG machine is designed. The sheet electrode servomechanism and other key mechanical components are designed. And the whole prototype machine is developed. The sheet electrode servomechanism can keep a right discharge gap between the sheet electrode and the wheel, and store unused sheet electrode within it.A new pulse power supply with novel topology and control strategy is put forward, taking into account specific requirement of the EDG machine and the low energy utilization rate of traditional pulse powers which use limiting resistors. The new power supply can provide large-scale adjustable peak voltage, pulse width and pulse interval. Current limiting resistors, which consume high energy, has been eliminated and the energy utilization rate is almost doubled.A servo-control system for the DC motor of the sheet electrode servomechanism is designed based on PWM with feedback. It can guarantee the stable low-speed turning of the motor. Using AC-DC-AC frequency control and computer control technology, the control circuit of the motor for grinding wheel spindle is designed.Through a series of experiments, the effects of electrical and non-electrical parameters such as pulse width, pulse interval, peak voltage, peak current, feeding speed, working fluid etc. on material removal rate and surface roughness of the non-conductive engineering ceramic workpieces are discussed in detail.Experiments for single-pulse discharges on non-conductive engineering ceramics are studied. Effects of the parameters on the discharge craters size are discussed. The mechanism of discharge and material removal is analyzed.更多还原