立铣刀渐进磨损过程中主电机功率信号的时域特性研究

根据立铣刀刀齿渐进磨损过程中主轴电机功率信号的变化特点 ,分析了主轴电机功率与刀齿后刀面磨损带面积 (AVB)间模型的时域统计特性 ,提取了反映刀具磨损状态的时域统计特征参数。相关试验证明了研究结果的正确性。     

铣削力模型的频域特性研究

根据铣刀刀齿渐进磨损过程中切削力信号的变化特点 ,分析了切削力与刀齿后刀面磨损带面积 (AVB)间模型的频域统计特性 ,提取了反映刀具磨损状态的频域统计原始特征参数并进行了相关试验研究     

基于砂轮磨损参数的立铣刀后刀面磨削轨迹补偿算法

整体立铣刀后刀面通常采用数控工具磨床按照理想砂轮形状的运动轨迹进行磨削加工,然而在实际磨削过程中,砂轮参与磨削的区域(主要是砂轮边缘轮廓)会逐渐磨损,从而导致后刀面几何精度下降甚至轮廓错误.针对该问题,本文提出了基于砂轮磨损参数的整体立铣刀后刀面磨削轨迹补偿算法.首先,针对立铣刀后刀面磨削工艺,定义了磨削坐标系,推导了...     

高速铣削时刀夹联体振动特性影响后刀面磨损机理

通过对主轴-刀夹-刀具联体的振动特性及切削过程分析,研究高速铣削时后刀面机械振动磨损的机理.采用试验模态分析方法, 获得刀夹联体的振动特性参数.分析刀尖的振动轨迹曲线以及有效切削后角随时间的变化规律,找出振动特性参数与后刀面磨损的关系.进行刀夹联体的振动特性参数影响后刀面磨损的切削试验.试验结果证明:在高速铣削硬钢材料时,刀夹联体的模态阻尼比和固有频率的乘积值越大,动刚度越高,后刀面振动磨损程度就越轻.     

基于神经网络的BTA刀具磨损量预测

用单齿BTA刀具进行深孔钻削时,刀具磨损通常以刀齿后刀面磨损为主。本文提出一种基于人工神经网络的后刀面磨损值预测方法,采用试验设计的方法进行BTA钻削试验,通过万能工具显微镜来测量刀齿后刀面的磨损值,得到训练样本。通过有限的训练样本建立关于切削速度、进给量和轴向力的刀齿后刀面磨损量的预测模型,然后运用MATLAB进行仿真与计算。试验和仿真结果表明,该模型能有效预测刀齿后刀面磨损值,为减少刀具磨损提供了依据。     

砂轮磨损对锥度球头立铣刀前角的影响研究

基于直柄球头立铣刀前后刀面的磨削加工运动关系,推导出锥度球头立铣刀前刀面的磨削加工运动关系,以SolidWorks软件为开发平台,利用Visual Basic 6.0进行二次开发,开发出锥度球头立铣刀前刀面的磨削加工仿真系统和刀具参数分析系统,从而模拟加工出锥度球头立铣刀的前刀面,得出较为理想的刃形曲线。然后分析了砂轮直径磨损对锥度球头立铣刀球刃前角和周刃前角的影响,用以指导锥度球头立铣刀的实际生产。     

微织构刀具连续磨损建模与仿真研究

建立切削过程中的微织构刀具连续磨损有限元模型一直是难点。为分析微织构刀具连续磨损问题,基于能量损失法,在有限元分析软件中建立了硬质合金刀具微切削Ti6Al4V钛合金材料过程中的微织构刀具连续磨损模型,并在刀具前刀面不同位置分别设计单个和多个微织构模型,分析微织构对刀具前刀面月牙洼磨损和后刀面磨损的影响。有限元分析结果表明,前刀面的微织构数量和位置对刀具的磨损程度有严重影响;刀具表面温度是影响月牙洼磨损深度的关键因素;而月牙洼磨损中心到切削刃刀尖的磨损与刀具的Mises应力有直接关系;影响刀具的后刀面磨损主要因素是刀具压力。     

砂轮磨损对球头立铣刀刃形的影响

采用贵州大学提出的球头立铣刀前刀面造型方法,在Solid Works平台上,借助VBA(Visual Basic for Applications)进行二次开发,建立了一套球头立铣刀前刀面虚拟磨削制造系统。以Solid Works为开发平台,对球头立铣刀前刀面的刃磨过程进行仿真,对砂轮磨损前后的刃形曲线进行比较,分析误差产生的原因,为将来砂轮磨损的误差补偿研究提供支持。     

基于后刀面磨损的铣削加工误差研究

对铣削加工过程中后刀面磨损对加工精度的影响进行了分析和研究,建立了基于刀具后刀面磨损的铣削加工误差的数学模型。     

球头立铣刀的建模设计及仿真系统的研究

以球头立铣刀的正交螺旋形刀刃曲线为基础。设计了锥形砂轮刃磨铣刀前后刀面的方式。分别推导与建立了具有等法向前角的前刀面、等主后角的后刀面的球头立铣刀的数学模型。并根据模型开发了球头立铣刀的计算机仿真设计与分析软件。     

Tool wear in turning of titanium alloy after thermohydrogen treatment

The influence of hydrogen contents on the tool wear has been mainly focused on the flank wear of the common tool,and the influence of hydrogen contents on the rake crater wear(main wear type) of the tool,particularly for the fine granular material tool,has been less investigated comprehensively.In this paper,for the purpose of researching the influence of hydrogen contents on tool wear,the titanium alloy Ti-6Al-4V is hydrogenated at 800 ℃ by thermohydrogen treatment technology and the turning experiments are carried out by applying uncoated WC-Co cemented carbide tool.The three-dimensional video microscope is used to take photos and measure tool wear.The results show that both of crater wear depth(KT) and average flank wear width(VB) firstly decreases and then increases with the increasing of hydrogen content.The maximum reducing amplitude of KT and VB is about 50% and 55%,respectively.Under the given conditions,the optimum hydrogen content is 0.26%.It is considered that the reduction of cutting temperature is an important factor for improving tool wear after the Ti-6Al-4V alloy is properly hydrogenated.Furthermore,the reasons of hydrogen effect on the tool wear are chiefly attributed to comprehensive effect of hydrogen contents on microstructure,physical properties and dynamic mechanical properties of the Ti-6Al-4V alloy.The proposed research provides the basic data for evaluating the machinability of hydrogenation Ti-6Al-4V alloy,and promotes practical application of thermohydrogen treatment technology in titanium alloys.     

刀具后刀面磨损量对切削力及加工表面粗糙度的影响

通过切削试验探索了在相同的工件材料、刀具材料、切削参数(切削深度、进给量)和不同的刀具磨损状态(后刀面磨损量)下,刀具后刀面磨损量(VB)对切削过程中的切削力及工件表面粗糙度的影响,并对这些影响的产生机理进行了讨论。     

Tool wear estimation in machining based on the flank wear inclination angle changes using the FE method

Abstract

In this study, a FEM-based tool wear approach with a focus on the geometry of the worn tool, especially the changes of flank wear land inclination angle, was developed. The relationship between the variables of the wear rate equation and the average nodal temperature on the flank wear land through integrating FE-simulations of the cutting process and Response Surface Methodology (RSM) was determined in order to define the temperature as a function of wear rate model parameters. Then, that data was used to calibrate the wear rate equation which was obtained by establishing the relationship between the Usui wear rate equation and the geometry of the worn tool, using a MATLAB program. This approach was validated by comparing the predicted flank wear rates and experimental measurements. The estimated flank wear shows some improvement compare to the model with a constant inclination angle.     

Cutting Force Model for a Small-diameter Helical Milling Cutter

In the milling process, the major flank wear land area (two-dimensional measurement for the wear) of a small-diameter milling cutter, as wear standard, can reflect actual changes of the wear land of the cutter. By analyzing the wearing characteristics of the cutter, a cutting force model based on the major flank wear land area is established. Characteristic parameters such as pressure parameter and friction parameter are calculated by substituting tested data into their corresponding equations. The cutting force model for the helical milling cutter is validated by experiments. The computational and experimental results show that the cutting force model is almost consistent with the actual cutting conditions. Thus, the cutting force model established in the research can provide a theoretical foundation for monitoring the condition of a milling process that uses a small-diameter helical milling cutter.     

硬质合金材料及其涂层对不锈钢加工中刀具边界磨损的影响

硬质合金刀具在不锈钢加工中,其刀具耐用度主要是取决于后刀面边界磨损而不是主切削刃后刀面的平均磨损量。为了提高刀具耐用度,就必须减小后刀面边界磨损。本文对奥氏体不锈钢（ＳＵＳ３０４） 在车削及铣削加工中,采用Ｍ２０ 、Ｋ２０ 和Ｚ２０ 材料以及ＴｉＮ、Ｔｉ（Ｃ,Ｎ） 和（Ｔｉ,Ａｌ）Ｎ 物理涂层（ＰＶＤ）的硬质合金刀具进行了耐边界磨损的研究     

COMBINED EFFECTS OF FLANK AND CRATER WEAR ON CUTTING FORCE MODELING IN ORTHOGONAL MACHINING—PART II: BAYESIAN APPROACH-BASED MODEL VALIDATION

Flank and crater wear are the primary tool wear patterns during the progressive tool wear in metal cutting. Cutting forces may increase or decrease, depending on the combined contribution from the flank and/or crater wear. A two-dimensional (2D) slip-line field based analytical model has been proposed to model the force contributions from both the flank and crater wear. To validate the proposed force model, the Bayesian linear regression is implemented with credible intervals to evaluate the force model performance in orthogonal cutting of CK45 steels. In this study, the proposed analytical worn tool force model-based predictions fall well within the 75% credible intervals determined by the Bayesian approach, implying a satisfactory modeling capability of the proposed model. Based on the parametric study using the proposed force model, it is found that cutting forces decrease with the increasing crater wear depth but increase with the increasing flank wear length. Also, the predicted cutting forces are affected noticeably by the friction coefficients along the rake and flank faces and the ratio of crater sticking region to sliding region, and better knowledge of such friction coefficients and ratio is expected to further improve worn tool force modeling accuracy. Compared with the finite element approach, the proposed analytical approach is efficient and easy to extend to three-dimensional worn tool cutting configurations.     

An analysis of the wear features of worm gear tooth flanks

Worm reducers with a double enveloping toroidal surface are a new type of reducer with higher wear resistance and longer service life. A series of contact fatigue tests of worm pairs has been carried out on a microcomputer-controlled test stand of closed power flow type, using an incremental method of increasing the load. During the test, the worm tooth flank completed 2.2 × 10⁷ cycles, and the worm gear tooth flank 1.1 × 10⁶ cycles. Meanwhile, the state of the flank was duplicated by means of a chemical film. This paper discusses the whole process of the occurrence and development of surface cracks as well as the formation of fatigue peeling. It should provide a reliable basis for definition of the law of fatigue damage of the worm gear tooth flank.