通过轴向力监测预报微钻头折断的研究

对以轴向钻削力为监测对象的微孔钻削在线监测进行了研究。以50支直径为0.4mm的高速钢麻花钻为样本,在数控高速精密微孔钻床上,对钻削45#碳素钢时微钻头折断的轴向钻削力极限值进行了检测。经参数估计和统计检验,得到轴向钻削力极限值服从对数正态分布的结论,并建立了基于可靠性的轴向钻削力监测阈值的确定方法。在此基础上选取不同可靠度水平进行了在线监测实验,与普通钻削比较,当选取可靠度水平为0.999时,在钻头利用率相同的情况下,10支钻头的折断率由30%下降到0,为避免发生微钻头折断这一长期困扰微孔加工的技术问题提供了一种良好的工艺方法。     

微孔钻削加工的钻削力监控

对以钻削力为监测对象的微孔钻削实时监测系统进行了研究。建立了一个BP神经网络模型，利用该模型对钻削过程进行监测。有效地避免了微钻头的折断，提高了微钻头的利用率。     

基于粗糙集模糊控制的微孔钻削在线监测

提出了一种基于粗糙集模糊控制的微孔钻削在线监测的方法。克服了当模糊系统输入维数高时,系统模糊规则过多,计算过于复杂的缺点。在MATLAB环境下,应用构造好的模糊系统对主轴电机三相电流信号进行实时数据处理,获取隐含微细钻头磨损状态的信息值,对微孔钻削过程进行在线监测实验,结果表明,适当选择监测阈值,可以有效避免微细钻头的折断。     

基于粗糙模糊神经网络的微孔钻削在线监测方法

提出了基于粗糙集理论的模糊神经网络对微孔钻削进行在线实时监测的方法,能有效利用粗糙集理论对控制规则进行约简,再利用钻削力、钻削扭矩和主轴电机电流信号作为神经网络的输入,构建相应的模糊神经网络模型,对系统进行训练,进而对提取的精简规则参数进行优化,从而解决了常规粗糙集控制规则缺乏学习能力,自适应性差的问题.采用该方法可获取微细钻头磨损状态的信息,对微孔钻削过程进行在线实时监测,可有效避免微钻头折断,并降低制造成本,提高生产效率.     

微钻头螺旋槽对称性对钻头折断的影响

在微孔钻削过程中,影响钻头寿命的因素很多：如微钻头自身的直径,微钻头钻芯厚度,微钻头材料及制造工艺,以及微钻头螺旋面等。集中研究微钻头螺旋槽对称性对钻头折断的影响,并在前人提出的钻头制造方法及钻削过程中钻头受力情况研究的基础上,分析了微孔钻削过程中,由于微钻头螺旋槽的制造误差,造成两主切削刃上的钻削力不平衡,导致微孔钻削过程中微钻头的折断。同时,提出了改善微孔钻削过程中微钻头折段的措施以及最适合制造微钻头的方法。     

基于神经网络的微孔钻削力的实时监控

建立了基于神经网络的微孔钻削力实时监控系统,以轴向力和扭矩信号为监测对象,应用BP神经网络进行多路传感器信息融合,判断微钻头工作状态,为微孔钻削加工力的智能化在线监控提供一种有效的技术方法.     

基于粗糙模糊神经网络的微孔钻削在线监测

为解决微孔钻削过程中信号特征与钻头磨损状态关系模型难以建立这一问题,提出一种基于粗糙集理论的模糊神经网络关系模型,首先运用粗糙集理论从数据样本中进行规则集约简,使得网络的模糊规则数目减少,克服了当输入维数高时,模糊神经网络模糊规则过多,结构过于庞大的缺点.然后根据这些规则来设计神经网络的结构模型.应用构造好的网络对主轴电机三相电流信号进行实时数据处理,获取隐含微细钻头磨损状态的信息值,对微孔钻削过程进行在线监测实验,结果表明,适当选择监测阈值,可以有效避免微细钻头的折断.     

基于多信号模糊融合的微孔钻削在线监测

利用轴向力、扭矩和主轴电机电流信号来监测微小钻头在钻削过程中的状态,提出了运用模糊控制作为多信号融合来监测微钻头状态的监测模型。结果表明,利用该模型得到的监测阈值进行在线监测可有效避免钻头折断。     

微孔钻削钻头折断原因分析

微孔孔径仅0.1～0.35毫米,用高速钢麻花钻钻削,钻头极易折断。作者在国内许多有微孔钻削的厂家进行了实地调查,并进行了分析研究,归纳出了钻头折断的原因和应采取的措施。     

微钻头主切削刃对微孔钻削的影响

集中论述了在实际微孔钻削加工过程中主切削刃对微钻头折断和微孔加工精度的影响。     

高速微孔钻床主轴系统的动态特性分析

依据转子动力学理论，利用Timoshenko粱轴理论，建立了包含旋转惯性力、陀螺力矩、离心力、弯曲变形、扭转变形、钻削轴向力和钻头的三种边界条件在内的高速微孔钻床主轴系统动力学模型。在利用实验和现有文献对所建立的模型进行了检验的基础上，对高速微孔钻床主轴系统的临界转速、临界轴向压力进行了分析。结果表明高速微孔钻床主轴系统的临界转速随钻削轴向压力的增大而减小，并且钻削过程中比刚入钻时能承受更高的转速，更大的轴向力；临界轴向压力随高速微孔钻床主轴系统转速的升高而降低，即随着钻削转速的提高，应适当减小钻削轴向力。     

Design and experimental study of an end effector for robotic drilling

This paper presents the development of a drill end effector for use on industrial robots. The end effector has low weight and high rigidity. The drill end effector is fully programmable and will realize different drilling mode. The real-time force feedback can detect dull or broken bits, drill to breakthrough, and plot thrust force while drilling. Additionally, the end effector can also be equipped with a coolant/lubricant device. Based on the drill end effector, an experimental study on dry drilling of Ti-6Al-4V alloy and 7075-T6 alloy bimetal stacks was performed by using an uncoated cemented carbide drill. The hole quality (hole size, surface roughness) and thrust force were evaluated at various spindle speeds, feed rates, stacking sequence, and clamp force. This study indicates that the spindle speed and feed rate have an effect on the hole quality and thrust force by means of changing the temperature and plastic deformation of cutting zone. The results show that drilling 7075-T6 alloy firstly would be most efficient because of the high hole quality and the low thrust force. It was also found that high clamp force is helpful to improve the hole quality.     

Artificial neural network based tool condition monitoring in micro mechanical peck drilling using thrust force signals

Micro scale machining process monitoring is one of the key issues in highly precision manufacturing. Monitoring of machining operation not only reduces the need of expert operators but also reduces the chances of unexpected tool breakage which may damage the work piece. In the present study, the tool wear of the micro drill and thrust force have been studied during the peck drilling operation of AISI P20 tool steel workpiece. Variations of tool wear with drilled hole number at different cutting conditions were investigated. Similarly, the variations of thrust force during different steps of peck drilling were investigated with the increasing number of holes at different feed and cutting speed values. Artificial neural network (ANN) model was developed to fuse thrust force, cutting speed, spindle speed and feed parameters to predict the drilled hole number. It has been shown that the error of hole number prediction using a neural network model is less than that using a regression model. The prediction of drilled hole number for new test data using ANN model is also in good agreement to experimentally obtained drilled hole number.     

变进给量振动钻削微孔的研究

提出了变进给量振动钻削新方法,并分析了其降低微孔钻削入钻位置误差的机理,采用直径为０．２８ｍｍ的高速钢麻花钻对１８Ｃｒ２Ｎｉ４ＷＡ低碳合金结构钢做了对比钻削实验,结果显著降低了微孔的入钻位置误差,验证了这种新方法优良的工艺效果。     

Tool wear monitoring in drilling using force signals

Utilization of force signals to achieve on-line drill wear monitoring is presented in this paper. A series of experiments were conducted to study the effects of tool wear as well as other cutting parameters on the cutting force signals and to establish the relationship between force signals and tool wear as well as other cutting parameters when drilling copper alloy. These experiments involve four independent variables; spindle rotational speed ranging from 600 to 2400 rev min⁻¹, feed rate ranging from 60 to 200 mm min⁻¹, drill diameter ranging from 5 to 10 mm, and average flank wear ranging from 0.1 to 0.9 mm. A statistical analysis provided good correlation between average thrust and drill flank wear. The relationship between cutting force signals and cutting parameters as well as tool wear is then established. The relationship can then be used for on-line drill flank wear monitoring. Feasibility studies show that the use of force signal for on-line drill flank wear monitoring is feasible.     

钻头磨损检测与剩余寿命评估

对钻头的磨损程度进行实时检测有助于对钻削加工过程实施预防性维护,提醒及时换刀。针对自动化生产中的刀具监测问题,给出一个基于主轴电流检测的钻头磨损状态分析和剩余寿命预测的应用策略。通过主轴电流传感器采样加工过程的电流信号,使用一个滑动窗口从连续采样数据中得到真实加工段数据,采用小波包分解的方法进行特征提取。基于Fisher标准筛选出最能表达磨损过程的若干特征。最后利用逻辑回归法和自回归滑动平均模型相结合的方法评估当前钻削加工的可靠性,预测钻头的剩余寿命。试验证明此方法的有效性,可为换刀决策提供依据。     

卧式复合材料高速钻削试验台的研制

对卧式复合材料高速钻削试验台的机械结构和控制、检测系统进行了简要介绍。本高速钻削试验台主轴最高转速可达到24000r/min,并且转速由零到最高转速连续可调;进给机构可实现工作台的0.4-24mm/s无级可调自动进给,可完成不同切削速度合肥市不同进给量下钻削力的测定、钻头磨损及耐用度、钻型比较、孔出口高速摄影及摄像等试验研究工作。     

高速小钻头温度与热应力场特性研究

基于传热学和金属切削理论,建立了某型高速钻头温度场模型.利用有限元法,模拟该钻头在典型工况的温度场分布及变化规律,研究了切削速度等参数对温度场的影响,得到了钻头在温度载荷下的应力和变形,计算结果表明,高速钻削最高温度出现在钻头尖部,沿轴向逐渐降低,对于小直径钻头心部与表面温差不显著;最高温度随着转速升高而升高,达到一定值后上升趋势逐渐变缓进而下降;刀具热变形较小,但热变形量可能会影响加工精度,应调整刀具材料或加强冷却;切削温度基本不影响其强度.     

淬硬钢高速微小孔钻削工艺试验研究

从淬硬钢高速微小孔钻削时钻头承受的负荷入手,以HRC62淬硬轴承钢材料为对象,通过试验的方法,检测和分析钻削过程中动态切削力(轴向力和扭矩)的特征,研究淬硬钢微小孔钻削的可行性和切削条件。并通过试验研究切削速度、进给量等钻削工艺参数对切削力的影响规律,提出改善硬态切削性能、提高钻头耐用度的淬硬钢微小孔钻削工艺规范。