【作者】 郑小虎；

【导师】 陈明；

【作者基本信息】 上海交通大学 ， 机械制造及其自动化， 2013， 博士

【摘要】 随着科学技术的发展，微小零件和装置的需求在不断增加。零件的尺度不断减小，这给机械加工带来了新的挑战，微细切削技术也随之发展起来。微细切削中的尺寸效应、刀具强度、刃口强度以及加工质量控制等是微细切削研究的核心问题。本文以PCB微孔钻削和金属微细铣削为研究对象，以微细切削加工质量控制为研究目标，对微细切削过程中涉及的材料去除机理、尺寸效应、微细刀具的失效机理、微细刀具的结构设计和优化、微细切削工艺的优化等方面进行了研究，主要研究内容与创新之处总结如下：（1）研发三轴精密微细切削实验平台针对课题的研究需求独立设计研制了一台超高速三轴立式微细加工平台。该平台最高主轴转速达到300000rev/min，是目前同类实验平台中最高的。为了使高速电主轴在运行过程中的稳定性，选择了合理的电机布置方案并采用了大理石床身以提高系统刚性。该平台采用分辨率为0.1微米的光栅，重复定位误差为±1m，最大运行速度300mm/s，能够实现三轴联动。平台精度测试结果表明微细切削平台精度已经达到设计要求。（2）微细毛刺形成机理及抑制策略通过切削有限元和微细切削试验研究了微细铣削中的材料去除机理、以及毛刺形成机理。微细切削有限元仿真结果表明微细毛刺的尺寸随着刃口半径和未切切削厚度的增大而增大。摩擦系数增大对毛刺尺寸影响不大。增大切出角可以明显降低毛刺尺寸。通过PCB微孔钻削实验研究了PCB毛刺的形成机理及加工参数对PCB微细毛刺形成的影响。PCB钻削毛刺的入口毛刺和出口毛刺有所不同。在入口处主要是泊松毛刺。而出口处形成了侧翻毛刺。通过统计分析不同加工参数下的毛刺尺寸可知进给对毛刺尺寸的影响大于主轴转速的变化。（3）PCB微孔钻削尺度效应及钻削力分析建模PCB微孔钻削中的尺寸效应对钻削扭矩有明显的影响。通过计算不同进给下的切削比能发现，切削比能随着进给增大而减小。分析结果表明，每转进给量大于5微米后，钻削进入稳态过程。在钻削实验数据的基础上建立了PCB微细钻孔轴向力和扭矩的预测模型，验证实验结果表明预测模型与实验数据较为接近。针对直径0.4mm和0.6mm的微钻进行了预钻孔实验。实验结果表明横刃产生的轴向力占总轴向力的50%以上，尤其在钻削GFRP时横刃产生的轴向力占总轴向力的70%以上。（4）建立微细刀具刃口应力计算公式首先建立了D型微细铣刀的数学模型，得出了D型微铣刀的前角公式。实现了在给定刀具半径和前角的情况下的能够得到刀具结构参数。通过有限元分析方法对刀具结构进行优化。其次根据PCB微钻主刃和横刃区域受力分析建立了微钻刃口应力计算公式。在此公式基础上，以刀具材料的屈服强度为设计准则，建立微细钻头的刃口最小钝圆半径设计公式。最后提出了改进微钻刃口设计的具体方法，即依据临界切削厚度来设计刃口半径，并使微钻横刃的刃口半径大于主刃，在保证刃口强度可靠的前提下，使两个区域刃口都处在稳态剪切状态中，使刀具工作状态平稳。（5）基于模糊神经网络模型的刀具磨损状态的识别由于BP神经网络模型自身存在的收敛慢、局部最小值等缺陷，并不适应于微细刀具的实时监测。因此本研究采用模糊神经网络法建立了刀具磨损预测模型。通过对模型的训练与测试，可知模型实际输出结果与理想输出值吻合，验证了模糊神经网络应用于刀具状态监测，特别是实时在线监测的可行性。（6）微细加工质量控制策略的研究针对不同的微细加工对象，本文总结出了不同的加工质量控制方法。在抑制金属微细铣削毛刺方面，本研究提出以增大切出角的方式抑制微细铣削毛刺的形成。针对PCB板钻削，本文介绍了两种提高钻削质量方式，其一是优化刀具结构，其二是优化工艺参数。本研究通过满意度函数法，分别对刀具结构和钻削工艺参数进行了优化，得到的优化结果达到了优化目标。更多还原

【Abstract】 The demand of micro-components and micro-machine are increasing duo to the development ofmicro-electronic and precision instruments industry. The size of micro-components is getting moreand more smaller which cause many new problems in manufacturing of micro-components. In orderto solve these problems, micro-cutting technology develops in recent years. The key point inmicro-cutting technology involves size effect, tool strength, tool radius strength and control ofmachining quality.The objective of this research is to study the mechanism of material removal process, sizeeffect, tool failure and optimize the tool geometry and manufacturing process in micro-drilling ofprinted circuit board and milling of alloy. The main contents and innovations are as followings:(1) Development of3-axis micro-cutting machine toolA3-axis micro-cutting machine tool was developed for the investigation of micro-cuttingtechnology. The maximum spindle speed is300000rev/min and the maximum moving speed is300mm/s. Some tests were carried out to analyze the performance of machine tool. The items oftests involve position accuracy, spindle error and natural frequency of frame. The results showedthat this machine met the requirements of micro-cutting experiments.(2) The mechanism and control of micro-burr formationThe mechanism of material removal process and micro-burr formation was investigatedthrough FEM simulation and micro-cutting experiments. The results of FEM simulation showedthat the burr size increased when tool edge radius increased. The friction coefficient has no obviouseffect on burr size. The increasing of exit angle can miniaturize the burr size. The experiments ofmicro-drilling of PCB were carried out to investigate the formation of micro-drilling burr. Theexperimental results showed that the entry burrs and exit burrs have different morphologies with thegeneration of entry burrs being mainly caused by burr bending, whereas the generation of an exitburr was more complicated. The effect of feed on burr size was bigger than sindle speed.(3) Size effect in micro-drilling of PCB and modeling of thrust force and torqueThe size effect of micro-drilling of PCB can be expressed by variation of torque. Thecalculated specific cutting energy decreased when feed increased. The experimental results showed that the specific cutting energy become constant when feed per tooth exceed5m. The empiricalmodel of thrust force and torque were established according to the drilling experiments. The resultsof the verification test showed that the established models had good agreement with experimentaldata. The experiments of drilling pilot hole with0.4mm and0.6mm micro-drill bits were carried out.The experimental results showed that the thrust force generated by chisel edge is50%of the wholethrust force. At the stage drilling GFRP, over70%of the trust force was generated by chisel edge.(4) Modeling of micro-tool geometry and design of tool edge radiusFirstly, a mathematical model of D-type micro-milling tool and the equation of calculating rakeangle were established. By these models, a D-type micro-tool can be designed by giving tool radiusand rake angle. After that, the geometric parameters of micro-tool were optimized by FEM method.Secondly, the equation of calculating stresses was established by analyzing drilling force. After that,a method of designing tool edge radius was given.(5) Investigation of tool wear condition monitoring based on Fuzzy neural networkDuo to the defect of slow convergence, BP neural network method was not fit for on-line toolmonitoring. Fuzzy neural network (FNN) method was used in this research to establish a predictionmodel for tool monitoring. This model was developed by training process, the results of verificationtests showed that the predicted output results had good agreement with ideal output results. It can beconcluded that FNN method is fit for on-line tool monitoring.(6) The strategies of controlling micro-machining qualityIn order to improve the machining quality, this paper gave different method for respectivemicro-machining processes. To mill the titanium alloy, minimum quantity lubrication (MQL)technology was advised. The experimental results showed that MQL can decrease burr formationand tool wear. To decrease burr formation in micro-milling, increasing exit angle is feasible. Toimprove the quality of drilling PCB, the optimization of tool geometry and machining parameterswere feasible. Composite desirability method was used to optimize the tool geometry and drillingparameters.更多还原