超声ELID复合内圆磨削ZTA纳米复相陶瓷的磨削机理

发布时间：2019-05-18 00:28

【摘要】：纳米复相陶瓷以其优异的力学性能、稳定的化学性能和较低的微缺陷敏感性,正成为国民经济和尖端科技领域的一类关键性材料。不过,纳米复相陶瓷的应用需要很高的形状尺寸精度和表面完整性,其加工仍然较困难,突出表现为难以同时实现高精度、高效率和高可靠性加工。本文将以精密高效为主要特征的超声振动技术和以超精密镜面为主要特征的ELID(在线电解修锐)磨削技术相复合,以ZTA纳米复相陶瓷为载体,研究超声振动参数、磨削参数与ELID参数之间的关系及其对磨削过程的影响,以及超声ELID磨削工艺参数对工件表面纹理的影响关系,以揭示超声ELID磨削纳米复相陶瓷的磨削机理,为进一步完善硬脆材料高效镜面加工理论和技术提供支撑。首先搭建超声ELID复合磨削ZTA纳米陶瓷试验研究平台。主要工作包括:基于波动理论和ANSYS有限元模态分析方法设计超声振动系统;分别设计电解装置的阳极和阴极,然后将它们集成为ELID装置;根据电火花加工原理,并通过调节整形各阶段的参数,对铸铁结合剂金刚石砂轮进行整形试验,使砂轮的初始圆度误差由32μm降低到约2μm,大多数磨粒凸出铸铁结合剂表面,从而达到砂轮精度要求。然后根据超声ELID复合内圆磨削砂轮氧化膜生长和去除的电化学原理,并考虑轴向超声振动辅助磨削几何参数等因素,建立任意时间超声ELID复合磨削砂轮氧化膜厚度预测模型。对该模型进行仿真分析的结果表明:在氧化膜厚度近似线性增长阶段,极间间隙越大,则氧化膜形成厚度越小,形成速度越慢;磨粒体积比越大,则氧化膜形成厚度越大,形成速度越快;占空比越大,则氧化膜形成厚度越大,形成速度越快。在氧化膜厚度呈非线性增长阶段,超声频率越高,则成膜速度越快,平衡时形成的氧化膜厚度越大。接着开展单因素试验,归纳出电源电压、脉冲宽度与脉冲间隔、极间间隙、砂轮转速及超声振动对超声ELID复合磨削预修锐阶段氧化膜的厚度、形成速率、表面形貌的影响机理;通过改变砂轮转速、工件转速、磨削深度、砂轮粒度,定性分析动态磨削过程中各参数对氧化膜状态的影响;进行停电光磨试验和停电光磨附加超声振动试验,揭示超声振动对氧化膜抛光性的影响机理。为验证砂轮氧化膜厚度模型,采集砂轮预修锐和动态磨削过程中测量点的厚度值,同时理论计算测量点的参数值,结果表明,玻尔兹曼函数拟合的相关度较好,厚度测量值趋势与理论预测值趋势相仿,这反映氧化膜厚度随时间而不断增长,增长速度随时间而变缓,从而证实氧化膜厚度模型的合理性。其次在超声ELID复合磨削磨粒运动学分析和动态有效磨粒数模型构建的基础上,建立超声ELID复合磨削平均未变形磨屑厚度模型。接着开展超声ELID磨削ZTA纳米陶瓷材料去除特性试验,通过研究磨削深度与磨削力、工件表面粗糙度及表面形貌的变化关系,将磨削深度与磨削结果之间的关系转变为未变形磨屑厚度与磨削结果之间的关系。通过分析不同未变形磨屑厚度条件下磨削力和表面粗糙度的变化规律以及工件表面SEM(扫描电子显微镜)照片,确定ZTA纳米陶瓷材料去除的脆塑性转变条件为平均未变形磨屑厚度1.565μm。然后基于未变形磨屑厚度模型建立表面粗糙度模型,通过模型仿真和表面粗糙度试验证实表面粗糙度模型的正确性,继而证实未变形磨屑厚度模型及ZTA纳米陶瓷材料去除的脆塑性转变临界条件。最后通过磨粒切削轨迹分析和试验揭示超声ELID复合磨削表面创成机理。本文研究证实超声ELID复合磨削砂轮氧化膜厚度预测模型的合理性,为揭示超声ELID磨削纳米复相陶瓷的磨削过程奠定了一定的理论基础;超声ELID磨削ZTA纳米陶瓷材料去除的脆塑性转变临界切深的确立,为进一步改善纳米复相陶瓷表面质量提供了一定依据。
[Abstract]:The nano-phase ceramics, with its excellent mechanical properties, stable chemical properties and low sensitivity to micro-defects, are becoming a key material in the national economy and the advanced science and technology field. However, the application of nano-phase ceramics requires high dimensional accuracy and surface integrity, and the processing is still difficult, and it is difficult to achieve high precision, high efficiency and high reliability at the same time. In this paper, the ultrasonic vibration technology with high precision and high efficiency and the ELID (on-line electrolytic dressing) grinding technology with ultra-precision mirror as the main feature are combined, and the ultrasonic vibration parameters are studied by using the ZTA nano-phase ceramics as the carrier. The relationship between the grinding parameters and the ELID parameters and its influence on the grinding process, and the influence of the ultrasonic ELID grinding process parameters on the surface texture of the workpiece to reveal the grinding mechanism of the ultrasonic ELID grinding nano-phase ceramics, In ord to further improve that high-efficiency mirror processing theory and technology of the hard and brittle material. First, an ultrasonic ELID composite grinding ZTA nano-ceramic test research platform was set up. The main work comprises the following steps of: designing an ultrasonic vibration system based on the fluctuation theory and the ANSYS finite element mode analysis method; respectively designing the anode and the cathode of the electrolysis device, and then integrating the anode and the cathode of the electrolysis device into an ELID device; and adjusting the parameters of each stage by adjusting the parameters of each stage according to the electric spark machining principle, The diamond grinding wheel of the cast iron bonding agent is subjected to the shaping test, the initial roundness error of the grinding wheel is reduced from 32. m u.m to about 2. m u.m, and most of the abrasive grains project on the surface of the cast iron bonding agent, so that the accuracy requirement of the grinding wheel is achieved. Then, according to the electrochemical principle of the ultrasonic ELID composite inner circle grinding wheel oxidation film growth and removal, and considering the factors such as the axial ultrasonic vibration auxiliary grinding geometric parameters, an arbitrary time ultrasonic ELID composite grinding wheel oxide film thickness prediction model is established. The results of the simulation analysis of the model show that the larger the gap between the electrodes when the thickness of the oxide film is approximately the linear growth phase, the smaller the thickness of the oxide film, the slower the formation speed, and the larger the volume ratio of the abrasive grains, the larger the thickness of the oxide film, the faster the formation speed, and the larger the duty ratio, The larger the thickness of the oxide film, the faster the formation speed. In that non-linear growth phase of the oxide film thickness, the higher the ultrasonic frequency, the faster the film formation speed and the greater the thickness of the oxide film formed at the time of equilibrium. then a single factor test is carried out to sum up the influence mechanism of the power supply voltage, the pulse width and the pulse interval, the interelectrode gap, the grinding wheel speed and the ultrasonic vibration on the thickness, the forming rate and the surface appearance of the ultrasonic ELID composite grinding pre-repairing stage oxidation film; and by changing the rotating speed of the grinding wheel, The influence of the parameters on the state of the oxide film during the dynamic grinding of the workpiece, the depth of the grinding, the particle size of the grinding wheel and the qualitative analysis of the dynamic grinding of the workpiece were carried out, and the influence of the ultrasonic vibration on the polishing of the oxide film was revealed. In order to verify the thickness model of the oxidation film of the grinding wheel, the thickness of the measuring points in the pre-sharpening and dynamic grinding of the grinding wheel is collected, and the parameter value of the measuring point is calculated by the theory. The results show that the correlation between the fitting of the Boltzmann function is good, and the trend of the thickness measurement is similar to that of the theoretical prediction value. This reflects the increase of the thickness of the oxide film over time, and the growth rate is slow with time, thus confirming the rationality of the thickness model of the oxide film. Secondly, on the basis of the analysis of the kinematic and dynamic effective abrasive particle number model of the ultrasonic ELID composite grinding, the model of the average undeformed chip thickness of the ultrasonic ELID composite grinding was established. The relationship between the grinding depth and the grinding force, the surface roughness of the workpiece and the surface morphology was studied. The relationship between the grinding depth and the grinding result was changed to the relationship between the thickness of the undeformed chip and the result of the grinding. The change law of the grinding force and the surface roughness and the SEM (scanning electron microscope) photograph of the surface of the workpiece were analyzed by analyzing the change of the grinding force and the surface roughness. The brittle-plastic transition condition of the removal of the ZTA nano-ceramic material is determined to be the average undeformed abrasive chip thickness of 1.565. m u.m. The surface roughness model is then established on the basis of the non-deformed chip thickness model, and the correctness of the surface roughness model is confirmed by the model simulation and the surface roughness test. In turn, the critical condition of the brittle-plastic transition of the undeformed chip thickness model and the removal of the ZTA nano-ceramic material is confirmed. Finally, the formation mechanism of the ultrasonic ELID composite grinding surface is revealed by the analysis and test of the abrasive cutting trajectory. The rationality of the ultrasonic ELID composite grinding wheel oxide film thickness prediction model is studied in this paper, which lays a theoretical basis for revealing the grinding process of the ultrasonic ELID grinding nano-phase ceramics. The critical cutting depth of the brittle-plastic transition of the ultrasonic ELID grinding ZTA nano-ceramic material is established. In ord to further improve that surface quality of the nano-phase ceramic, a certain basis is provided.
【学位授予单位】：河南理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ174.6

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