瞬时铣削力数学模型及验证

在实际铣削加工中,由于铣削的断续性以及铣刀的多齿性,使得铣削力呈动态变化,动态变化的铣削力是造成工艺系统振动和工件变形的主要因素,因此建立准确的动态铣削力预测模型,是研究铣削加工工艺参数优化、铣刀结构参数优化和加工表面形貌预测的基础,并且对指导实际加工生产具有重要的意义。以微元铣削力为基础,通过计算某一时刻参与铣削的切削刃长度构造瞬时铣削力数学模型,并且结合试验验证了此模型的有效性,此模型为优化铣削加工提供了理论依据。     

3Cr13不锈钢的低频振动铣削影响问题研究

这里研究了低频振动铣削对3Cr13不锈钢铣削力变化的影响.基于对工件和刀具轨迹的运动学分析,对比分析了低频振动铣削与普通铣削的刀具轨迹变化情况,结果表明振动铣削影响了工件-刀具间的相对运动轨迹.采用单因素试验法研究了沿工作台进给方向对工件施加低频激励时不同参数对铣削力的影响规律.试验结果表明低频振动铣削可以减小铣削力,并且铣削力大小与顺/逆铣、激振频率、电压,以及机床主轴转速有关,在相同切削条件下顺铣比逆铣产生的铣削力小.     

立铣刀侧铣加工FV520B不锈钢的铣削力模型

基于瞬时刚性铣削力模型建立了立铣刀侧铣FV520B不锈钢的铣削力模型,考虑了立铣刀侧铣时刀具侧刃与工件的接触区域以及参与切削的切削刃数量,通过立铣刀侧铣FV520B不锈钢铣削力测试实验来标定铣削力模型中的铣削力系数。结果显示,侧铣实验获得的铣削力系数更加符合立铣刀在大切深和刀具变形较为明显的工况。对比实验结果与铣削力模型预测值发现,该模型能够较好地预测铣削力。     

PMMA微细铣削实验工艺研究

PMMA材料(聚甲基丙烯酸甲酯)具有低成本、生物相容性和光学特性等优点,常用于制造聚合物微流体装置,通过微细铣削实验,结合最小二乘法拟合,构建表面粗糙度的预测回归模型。以表面粗糙度值为判定依据,在所研发的三轴微细铣削机床上,通过在工件内侧和外侧下刀与顺逆铣相结合共六种不同的微细铣削方式,开展微细铣削工艺研究。研究表明,预测模型较为真实反映实验测量结果,当铣削方式一定时,从工件外侧下刀获得的表面粗糙度值比从工件内侧下刀获得的表面粗糙度值更小,顺逆铣混合时获得最小的表面粗糙度值,逆铣时表面粗糙度值最大。     

考虑工件变形的五轴侧铣薄壁件铣削力建模

针对铣削加工过程中工件和刀具接触关系的时变性所导致铣削力预测不精准的问题,提出一种综合考虑工件变形作用下的五轴侧铣铣削力建模方法。首先,基于机械Ⅱ型力学模型,综合考虑剪切力和犁切力作用,建立五轴铣削加工微元铣削力模型;其次,利用欧拉-伯努利梁理论计算工件在任意切削深度下的变形量;进而,更新工件变形量引起的切削深度变化,构建考虑工件变形的五轴侧铣薄壁件铣削力模型;最后,通过试验与模型预测结果对比,得出在考虑变形的情况下,X、Y方向上铣削力的平均峰值误差分别减小了4.42%和0.62%,验证了模型的有效性。     

网络环境下铣削仿真模型的集成

阐述了铣削力、铣削力矩和工件表面几何误差模型的建立。并采用CORBA技术对上述三种铣削模型及铣削系统颤振模型的集成进行了研究。采用合理的网络结构和分布式计算，系统的性能得到改进，实现了一个分布式铣削仿真系统。     

摆线轮轮廓高速周铣工艺系统的弹性铣削力预测方法

为了提高高速铣削过程中复杂薄壁结构件的加工精度,针对高速铣削摆线轮轮廓的工艺特点,建立摆线轮刚性轮缘和弹性轮缘的铣削力模型。该模型基于弯扭耦合弹性力学理论,建立薄壁轮缘的铣削变形模型;并结合周铣摆线轮轮廓时曲率沿路径连续变化的特点,基于工件—刀具的铣削变形,建立工艺几何模型;在此基础上推导出切削啮合角和瞬时切削厚度的表达式,采用改进的Newton-Raphson迭代算法,仿真出铣削摆线轮轮廓的铣削力。研究表明工件和刀具共同引起的径向综合变形是工艺系统变形的主要因素,并引起铣削力的变化;随着轮廓形状呈现周期性的变化,对应于摆线轮轮廓上的每齿进给量也呈现周期性的变化,使得铣削力呈现周期性变化。最后,经铣削试验验证,实测结果和仿真结果具有较好的一致性。     

基于近似模型的铣削工艺参数可靠性设计优化

针对现有铣削工艺参数优化方法未考虑设计参数不确定性,导致优化结果难以满足实际产品性能要求的问题,引入近似模型对铣削工艺参数进行可靠性设计优化。以铣削加工表面粗糙度为目标函数,以最大铣削力小于给定值的可靠度作为约束,综合考虑铣削加工过程中铣削速度和每齿进给量的变动,建立了铣削工艺参数可靠性优化模型,并分别采用Kriging近似和径向基函数近似对铣削表面粗糙度、铣削力与设计变量之间的隐式关系进行近似替代,最后采用Monte Carlo仿真-序列近似规划对模型进行了寻优求解,通过试验对可靠性优化的结果进行了验证。结果表明,该方法可有效地降低铣削加工表面粗糙度,并且可保证加工过程中最大铣削力的可靠度要求。     

端铣7055铝合金铣削力及铣削温升研究

通过试验构建了适合描述7055铝合金铣削加工过程的流动应力本构模型。采用有限元软件Deform-3D建立了接近实际的三维螺旋刃立铣刀单齿铣削加工数值仿真模型,通过仿真计算,获得了铣削7055铝合金过程中的铣削力和铣削温度,分析了铣削速度、进给量、铣削深度等工艺参数对铣削力和铣削温度的影响规律。结果表明,铣削力和刀尖处工件温度都随着铣削速度、进给量、铣削深度的增大而增大,但增大的程度及影响机理不尽相同。最后通过铣削力和铣削温度测量试验对有限元计算结果进行了验证。     

铣削粉末冶金高温合金FGH95时工件温度的研究

镍基粉末高温合金具有屈服强度高、疲劳性能好等优点,是制造新型发动机涡轮盘的理想材料,工件温度是引起工件各种形式热损伤的主要因素,本文研究铣削粉末冶金高温合金FGH95时工件的瞬态温度。对铣削过程进行合理简化,基于移动热源法建立粉末冶金高温合金铣削时工件温度的解析模型,研究铣削速度对工件温度的影响规律。通过铣削试验对工件温度模型的有效性进行验证,试验结果表明建立的二维工件温度解析模型能正确预测铣削高温合金时工件加工表面的温度分布。     

基于BP神经网络的立铣加工振动快速预估

结合研制的立铣加工过程虚拟仿真系统和实验测量铣削力信号,训练并建立BP神经网络模型,快速实现铣削过程刀具-工件系统振动状态的预估.预估的振动结果与实验测量数据较为吻合,表明铣削虚拟仿真系统与神经网络技术的结合能够高效低耗地用于不同铣削加工条件下铣削振动状态的快速预估和加工过程监测.     

圆锥螺旋铣刀非线性铣削力模型

应用微分几何理论,推导了圆锥螺旋铣刀的几何特征,构造了三维非线性铣削力模型,提出了用双线性模型识别铣削力系数的方法。该模型具有精度高、铣削力系数与进给量相关性小和易于建立铣削力数据库等特点。仿真计算和试验结果表明该模型对圆锥螺旋铣削力预报是有效的。     

一种新的螺旋刃球头铣刀铣削力模型

为提高铣削加工的安全性和生产效率，有必要在加工实际进行之前准确地预测切削过程的物理信息，如铣削力、刀具振动等。给出了球头铣刀丸线几何模型，采用理论削力分析与实验--系数识别相结合的方法建立了新的螺旋刃球头铣刀的铣削力模型。对不同切削条件下的铣削力进行了仿真，与实验测量数据吻合良好，证明离线仿真可以对铣削力做出较准确的预测。     

Surface roughness modeling in Laser-assisted End Milling of Inconel 718

Inconel 718 is a difficult-to-machine material while products of this material require good surface finish. Therefore, it is essential for the evaluation and prediction of surface roughness of machined Inconel 718 workpiece to be developed. An analytical model for the prediction of surface roughness under laser-assisted end milling of Inconel 718 is proposed based on kinematics of tool movement and elastic response of workpiece. The actual tool trajectory is first predicted with the consideration of overall tool movement, elastic deformation of tool, and the tool tip profile. The tool movements include the translation in feed direction and the rotation along its axis. The elastic deformation is calculated based on the previously established milling force prediction model. The tool tip profile is predicted based on the tool tip radius and angle. The machined surface profile is simulated based on the tool trajectory with elastic recovery, which is considered through the comparison between the minimum thickness and actual cutting thickness. Experiments are conducted in both conventional and laser-assisted milling under seven different sets of cutting parameters. Through the comparison between the analytical predictions and experimental measurements, the proposed model has high accuracy with the maximum error less than 27%, which is more accurate for lower feed rate with error less than 3%. The proposed analytical model is valuable for providing a fast, credible, and physics-based method for the prediction of surface roughness in milling process.     

基于正交切削模拟的零件铣削加工变形预测研究

提出了基于正交切削模拟的零件铣削加工变形的预测方法,建立了三维铣削加工的有限元模型。基于正交切削加工模拟结果,利用铣削温度、铣削力的分析模型求解了三维铣削加工的瞬态温度和瞬态切削力,并将其作为动态载荷应用于三维切削加工的有限元模型,模拟了零件的三维铣削加工过程,预测了零件的变形。通过模拟结果与现场加工情况对比,证明该预测方法是行之有效的。     

微细铣削表面形貌形成分析

基于最小切削厚度的概念,提出了微细铣削过程槽底表面几何形貌仿真模型。通过微细铣削表面形貌的仿真和表面粗糙度Ra值的计算以及微细铣削实验,对微细铣削表面粗糙度随着每齿进给量变化的规律进行了分析和描述。     

Extracting cutting constants via harmonic force components for a general helical end mill

Mechanistic cutting constants serve well in predicting milling forces, monitoring the milling process as well as in helping to understand the mechanistic phenomena of a machining process for a unique pair of workpiece and cutter materials under various types of cutting edge geometry. This paper presents a unified approach in identifying the six shearing and ploughing cutting constants for a general helical end mill from the dynamic components of the measured milling forces in a single cutting test. The identification model is first presented assuming the milling force is measured with a known phase angle of the cutter spindle. When the phase angle of the cutter rotation is not available, as is the case for most milling machines, it is shown that the true phase angle can be identified through the theoretical phase relationship between the different harmonic components of the milling forces measured with an arbitrary phase angle. The numerical simulation and the experimental results for ball and cylindrical end mills are presented to demonstrate and validate the identification methods.     

Dynamic Force Modelling for a Ball-End Milling Cutter Based on the Merchant Oblique Cutting Theory

A new dynamic force model for a ball-end milling cutter is presented in this paper. Based on the principle of the power remaining constant in cuts, the Merchant oblique cutting theory has been successfully used for the differential cutting edge segment of a ball-end milling cutter. A concise method for characterising the relationship of the complex geometry of a ball-end milling cutter and the milling process variables is determined, so that the force coefficients can be decomposed. The geometric property of a ball-end milling cutter and the dynamics of the milling process are integrated into the general model to eliminate the need for the experimental calibration of each cutter geometry and milling process variable. The milling experiments prove that this model can predict accurately the cutting forces in three Cartesian directions.     

Cutting torque and tangential cutting force coefficient identification from spindle motor current

This article presents an enhanced methodology for cutting torque prediction from the spindle motor current, readily available in modern machine tool controllers. This methodology includes the development of the spindle power model which takes into account all mechanical and electrical power losses in a spindle motor for high-speed milling. The predicted cutting torque is further used to identify tangential cutting force coefficients in order to predict accurately the cutting forces and chatter-free regions for milling process planning purposes. The developed model is compared with other studies available in the literature, and it demonstrates significant improvements in terms of the completeness and accuracy achieved. The developed model is also validated experimentally, and the obtained results show good compliance between the predicted and the measured cutting torque. The developed enhanced procedure is very appealing for industrial implementation for cutting torque/force monitoring and tangential cutting force coefficient identification.     

球头铣刀切削力计算机预报模型的数值仿真

借助建立的铣刀切削力、扭矩和切削功率的计算机预报模型 ,对平前刀面球头铣刀的切削性能进行了数值仿真研究 ;通过分析各种切削参数对切削性能的影响规律 ,获得了不同切削条件下球头铣刀切削力和扭矩的特征和变化趋势