基于旋转电极的方孔电火花加工新方法研究

发布时间：2019-06-29 20:46

【摘要】：方孔结构具有较大转矩承载能力和高稳定性,在航空航天、汽车、船舶、石油和风电等工作环境恶劣对机械结构稳定性要求较高的领域被广泛采用。铣削、铸造等机械加工方法可以实现在普通材料上加工方孔,当需要在硬度大的材料上加工大深径比方孔时,通常采用特种加工方法。电火花方法常采用方电极加工方孔,加工时存在电蚀产物难以排出加工区域导致加工效率低、电极损耗大等问题。为提高电火花加工方孔的加工速度并减小电极损耗,本文提出一种利用旋转电极加工方孔的方法。将勒洛三角形作为电火花加工电极截面形状,分析勒洛三角形电极在与其等宽的方形约束孔中的运动形式,得到电极中心运动轨迹以及底面加工区域的形状和面积。根据分析结果研制方孔加工装置,完成加工装置零部件设计以及装配工作。使用加工装置加工出方孔证明利用旋转电极加工方孔具有可行性。将加工装置进行简化,在Adams/Views软件中建立简化后的加工装置数模,确定零部件空间位置并施加运动约束。利用运动轨迹仿真研究电极的长度、转速、形状精度、装夹误差以及导向机构约束位置对方孔形状精度的影响。根据电极在方孔中的转动运动,分析了旋转电极加工方孔时加工区域流场的变化规律,发现旋转电极加工过程中的转动对电蚀产物的排出具有促进作用。根据可行性实验以及运动轨迹仿真结果,对旋转电极方孔加工装置进行优化,提高了方孔的形状精度。在此基础上,通过单因素实验研究不同转速对方孔加工速度以及电极损耗的影响。设置旋转电极方孔加工方法和方电极方孔加工方法的对比实验,获得开路电压、伺服进给速度、检测阈值范围等加工条件对两种方法加工特性的影响规律。分别在两种加工方法最优加工条件下加工不同深度的方孔,发现随着加工深度的增加旋转电极方孔加工方法相比方电极加工方法在提高加工速度降低电极损耗方面的优势明显。
[Abstract]:Square hole structure has large torque bearing capacity and high stability, which is widely used in aerospace, automobile, ship, oil and wind power and other fields where the stability of mechanical structure is required. Milling, casting and other machining methods can be used to process square holes on ordinary materials. When it is necessary to process square holes with large depth-diameter ratio on materials with high hardness, special machining methods are usually adopted. Square electrode is often used to process square hole in EDM method, and there are some problems in machining, such as low machining efficiency and large electrode loss, which are difficult to discharge from the machining area. In order to improve the machining speed of EDM square hole and reduce the electrode loss, a method of machining square hole with rotating electrode is proposed in this paper. Taking the Lello triangle as the cross section shape of the electrode in EDM, the motion form of the Lello triangle electrode in the square constrained hole equal to its width is analyzed, and the movement track of the center of the electrode and the shape and area of the machining area of the bottom surface are obtained. According to the analysis results, the square hole machining device is developed, and the parts design and assembly of the machining device are completed. Using the machining device to process the square hole proves that it is feasible to use the rotating electrode to process the square hole. The machining device is simplified, the simplified digital model of the machining device is established in Adams/Views software, the spatial position of the parts is determined and the motion constraint is imposed. The effects of electrode length, rotating speed, shape accuracy, clamping error and constraint position of guide mechanism on the shape accuracy of hole are studied by motion trajectory simulation. According to the rotating motion of the electrode in the square hole, the variation of the flow field in the machining area is analyzed when the rotating electrode is machined. It is found that the rotation of the rotating electrode in the process of machining the rotating electrode can promote the discharge of the etched products. According to the feasibility experiment and the simulation results of motion trajectory, the machining device of square hole with rotating electrode is optimized, and the shape accuracy of square hole is improved. On this basis, the effects of different rotating speed on hole machining speed and electrode loss were studied by single factor experiment. The effects of open circuit voltage, servo feed speed and detection threshold range on the machining characteristics of the two methods are obtained by setting up the comparative experiment of the square hole machining method of rotating electrode and the square electrode square hole machining method. The square holes with different depths are machined under the optimal machining conditions of the two machining methods, and it is found that the rotating electrode square hole processing method has obvious advantages over the square electrode machining method in increasing the machining speed and reducing the electrode loss.
【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】：2017
【分类号】：TG661

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