基于刀具磨损的车削加工残余应力实验研究

通过车削实验测量刀具磨损不同阶段的加工残余应力和加工硬化层微观硬度,了解加工残余应力的分布和变化特点,并分析刀具磨损对车削加工残余应力变化的影响规律及原因。实验结果表明:车削加工残余应力在磨损前阶段变化缓慢,后阶段变化快速,变化趋势从拉-压应力混合状态过渡到纯压应力状态,变化速率和刀具磨损曲线不重合。     

CFRP切削加工中刀具磨损研究进展

从不同类基体材料的未涂层、涂层刀具2个方面,综述了CFRP切削加工用刀具的磨损部位及形式。现有研究均以宏、微观实验观测为主,宏观上,磨损位置以后刀面磨损及切削刃钝化最为常见;微观上表现为纤维硬质点与刀具间摩擦所致的磨粒磨损,随着切削温度、速度的提高,同时伴有粘着、氧化磨损。整体来说,金刚石类刀具耐磨性表现最佳,尤其适用于连续切削加工的场合。高强、高硬纤维高频刮擦作用下的磨粒、疲劳磨损仍是该类刀具磨损的主要威胁。当前所采用的辅助工艺(冷却气体、微量润滑、超声振动等)、涂层材料改性、微结构等方法,在一定程度上改善了摩擦条件,抑制了刀具磨损,但仍难以满足CFRP连续高质高效加工需求。可见,如何从微纳观多尺度方向深入研究金刚石类刀具的磨损机理及抑制策略,是CFRP高质高效加工的亟需。     

利用切削加工的刀具磨损精细加工金刚石单晶

金刚石单晶(SCD)具有优越的特性，其硬度极高，作为切削刀具对其精密加工是必不可少的。SCD金刚石作为产品在实际中使用时，必须加工成要求的形状。为了获得SCD的块状模型，通常广泛采用金刚石粉末加以抛光，但这种方法既不经济又太费时。为了使微切削加工用SCD获得要求的形状，本研究则利用切削过程中的刀具磨损，通过实验探讨以铁基材料精密加工SCD。研究发现，铁基材料可去除和抛光SCD，尽管SCD的硬度远远高于铁基材料。对去除率进行了测定，所加工的金刚石表面粗糙度相当于工业加工金刚石，而且比激光加工表面粗糙度要好得多。     

基于裂纹驱动推挤加工工程陶瓷新方法及刀具磨损研究

基于边缘效应驱动裂纹软推挤加工工程陶瓷是一种新的加工方法。为实现工程陶瓷等硬脆材料的高效、低成本加工,通过试验研究了加工过程中车刀进给速度、凸缘厚度、槽深三个重要加工参数对车刀磨损的影响规律。结果显示:基于边缘效应驱动裂纹软推挤加工,能充分发挥裂纹扩展的高速度、低能耗特点,从某种程度上实现了软的刀具加工硬度比它高的材料。切削实验表明:随着车刀轴向进给速度增大,车刀的磨损量减小;但当凸缘较厚时,进给速度过大可能会使车刀发生崩刃,凸缘厚度越厚,其断裂强度越好,所以车刀磨损增加;槽深越深时,断裂强度变差,车刀磨损减小;但随深度增加,车刀与材料接触增大,车刀磨损曲线折回,呈缓慢增大趋势。     

聚晶立方氮化硼刀具磨损与寿命研究综述

聚晶立方氮化硼(PCBN)是一种超硬刀具材料,由于其具有硬度高、化学稳定性和热稳定性好等优点,已经被广泛应用于汽车、航空航天、能源等领域的机械零部件加工。文中分析了PCBN刀具的主要磨损形式及其原因,并从刀具材料构成和几何形状、工件材料以及切削条件3个方面总结了影响PCBN刀具磨损和寿命的主要因素,最后介绍了切削参数优化和添加涂层等方法在提高刀具耐磨性与寿命方面的应用。     

基于时间卷积网络的刀具磨损在线监测

在刀具磨损监测领域中,传统卷积神经网络难以选择合适的卷积核大小,循环神经网络容易发生梯度消失和梯度爆炸,为克服以上缺点,引入时间卷积网络构建在线监测模型对刀具磨损量进行监测。考虑到原始数据量过大且每次走刀过程所采集数据量不同,对数据进行降采样处理,获得了大小为(7,5000)的网络输入数据。通过一维卷积神经网络和时间卷积块的依次叠加,对数据进行特征提取,使用全连接网络将特征映射到刀具磨损值。最后,使用PHM大赛中铣刀磨损的数据验证了模型的效果。实验结果证明,基于时间卷积网络的刀具磨损在线监测模型具有较强的泛化能力,在验证集上均方误差和平均绝对误差分别仅为65.16与6.21,相较于隐马尔科夫、梯度提升树等模型具有较大的提升。     

淬火 态模具钢对铣削加工刀具磨损的影响

各种模具高速铣 削是缩短模具加工时间的一种方法,它代替了粗加工、淬火和电火花加工。瑞 已有可能将淬火态的钢材直接铣削加工到要求的尺寸。可是,钢的种类及材料硬度对切削工具的磨损及被加工模具表面质量的影响很大。这项研究是以ＣＢＮ切削刀具加工不同硬度的各种模具钢,用改变切割速度来寻求每种材料在其淬火态的最佳切削速度,全文提供了一些研究结果。     

基于数字图像的刀具磨损状态检测技术

采用数字图像分割和亚像素边缘检测等图像处理技术自动测量刀具磨损边界的磨损量并与刀具磨钝标准比较,判断刀具的磨损状态,实现刀具磨损状态的间歇式在线自动检测。针对刀具的边缘特征,运用了中值滤波、对比度拉伸、迭代自适应二值化、基于分水岭分割、Roberts边缘算子、图像匹配、Zernike正交矩边缘检测和曲线拟合等数字图像处理技术,完成了刀具磨损量微米级的高精度检测。     

硬质合金刀具磨损寿命分布规律的适应性

本文从工件材料、刀具材料、刀具几何角度、加工机床及切削用量等方面对硬质合金刀具磨损寿命分布规律进行了适应性试验验证，结果表明，硬质含金刀具在不同加工条件下，其磨损寿命服从对数正态分布，并具有较好的适应性。     

基于加工表面纹理连通区域的刀具磨损状态研究

在车削加工过程中,随着刀具磨损量的增加,表现为工件表面的纹理结构发生变化,依据工件纹理的变化能够间接判断刀具的磨损程度.具体处理方法为:选取阈值作图像分割,对二值图像作区域标记,区域标记的最大值称作连通区域数,将二值图像的连通区域数作为刀具磨损的特征量.实验结果表明,随着刀具磨损量的增加,图像的连通区域数随之增加,它为刀具磨损在线检测提供了一种有效的手段.     

基于Lipschitz指数的刀具磨损补偿问题的研究

文章分析了金属切削加工过程中刀具磨损的规律以及在不同的刀具磨损阶段切削力信号的奇异性指数(即Lipschitz指数)的变化规律.根据这一变化规律对自动化生产过程中刀具磨损的补偿进行了规划.提出了刀具磨损自动补偿的实施方案.     

Effects of random aspects of cutting tool wear on surface roughness and tool life

The effects of random aspects of cutting tool flank wear on surface roughness and on tool lifetime, when turning the AISI 1045 carbon steel, were studied in this investigation. It was found that standard deviations corresponding to tool flank wear and to the surface roughness increase exponentially with cutting time. Under cutting conditions that correspond to finishing operations, no significant differences were found between the calculated values of the capability indexC _p at the steady-state region of the tool flank wear, using the best-fit method or the Box-Cox transformation, or by making the assumption that the surface roughness data are normally distributed. Hence, a method to establish cutting tool lifetime could be established that simultaneously respects the desired average of surface roughness and the required capability index.     

自动换刀装置刀时间计量方法

对常用的刀对刀、切削对切削的换刀时间如何计量进行了论述，并提出了一种新的位置对位置（position-to-position简称PTP）换刀时间计量方法，同时说明了这些计量方法的特点和应用。     

基于细胞神经网络刀具磨损图像的预处理

提出了一种基于细胞神经网络的刀具磨损图像处理方法，通过设计细胞神经网络参数，运用细胞神经网络对刀具的二值图像平滑滤波，边缘提取，通过仿真证明该方法是有效的，由于细胞神经网络易于用VLSI实现并且并行处理速度快，因此该方法对刀具的磨损状态机器视觉检测中的图像处理具有实用意义。     

A novel approach to quantifying tool wear and tool life measurements for optimal tool management

It is a common practice in batch production to continually use the same tool to machine different parts, using disparate machining parameters. In such an environment, the optimal points at which tools have to be changed, while achieving minimum production cost and maximum production rate within the surface roughness specifications, have not been adequately studied. The tool wear index (TWI) and the tool life model developed in this study use a novel approach, analyzing wear surface areas and material loss from the tool using micro-optics and image processing/analysis algorithms. With relation to surface roughness, the TWI measures the wear conditions more accurately and comprehensively, and the tool life model enables maximum use of a worn tool and minimum risk for in-process tool failure. The TWI and a surface roughness control model are integrated into an optimal control strategy that shows potential for productivity improvement and reduction of manufacturing cost.     

Tool wear mechanisms and tool life enhancement in ultra-precision machining of titanium

Titanium and its alloys are generally considered as difficult-to-machine materials due to their poor thermal conductivity and high strength, which is maintained at elevated temperatures. This paper examines the tool wear mechanisms involved in ultra-precision machining of titanium. In this study single-crystal diamond tools were used to machine commercial pure titanium (CP-Ti) and Ti-6Al-4V alloy. Industrial expectations for surface quality and tool life based on optical grade applications are presented. Results obtained from the characterization of the tool, chip and workpiece led to the identification of graphitization as the mechanism that initiates tool wear. As the cutting edge rounds-off due to graphitization the rate of adhesion of the workpiece material onto the tool increased, which caused the quality of the surface finish to deteriorate. To reduce this wear mechanism a protective barrier made of Perfluoropolyether (PFPE) polymer, was explored. Tribometer studies with PFPE coated diamond tools and titanium pins showed a reduction in the coefficient of friction (COF). Subsequent machining tests using PFPE coated diamond tools showed promising results in extending the tool life and enhancing the surface quality to a point where Ti can now be considered as a viable option for applications involving optical grade surfaces.     

基于有限元理论分析切削振动对CBN刀具磨损的影响

研究用CBN刀具切削钛合金Ti-6Al-4V材料时,切削振动对刀具磨损的影响情况。用有限元分析技术,设计正交试验,分析不同方向切削振动幅度和振动频率对刀具表面应力、刀具温度的影响,研究切削振动条件下的刀具磨损情况。有限元仿真结果表明:X方向振动对刀具表面应力和温度影响较小,且规律性影响不明显,因此X方向振动并未加重刀具磨损;Y方向振动对刀具表面应力和温度影响较大,刀具表面应力和温度随着Y方向振动幅度和频率增加而增大和升高,刀具磨损加重;当X方向和Y方向均存在振动时,刀具表面应力和温度也随着振动幅度和频率增加而增大和升高,刀具磨损严重。利用实际切削试验对有限元分析结果进行验证,发现振动对刀具磨损影响较大,与有限元分析结果基本一致。      

A study of the diamond tool wear suppression mechanism in vibration-assisted machining of steel

Inability of machining steel strongly inhibits the application of diamond machining in manufacturing industry, especially in the fields of ultra-precision and micro machining. In recent years, vibration-assisted machining (VAM) has been proved to be capable of efficiently suppressing the diamond tool wear in cutting steel. Currently, the prevailing speculation claimed by most researchers for such suppression is that the tool–workpiece flash temperature was reduced in VAM, which would slow the chemical reaction between iron on steel and carbon on diamond. However, the correctness of this speculation has not been proved by any experimental or theoretical research. In this paper, in order to understand the true wear suppression mechanism of diamond tools in VAM of steel, a study is conducted by measuring the workpiece temperatures and modeling the cutting energy consumption in both VAM and conventional cutting (CC). Based on the comparison results, it is concluded that the cutting temperature and energy consumption in VAM are not smaller than in CC, and hence the reduced diamond tool wear in VAM should not be caused by the claimed reduced temperature, especially when the material removal rate is very small. Finally, based on the EDS analysis and the comparison of experimental results under different air pressure, two probable reasons are proposed for the significantly reduced diamond tool wear in VAM of steel: (i) increase of gas pressure at the tool–workpiece interface and (ii) generation of an oxide layer on the freshly machined surface.     

Tool life determination based on the measurement of wear and tool force ratio variation

Non-linear regression analysis techniques are used to establish models for wear and tool life determination in terms of the variation of a ratio of force components acting at the tool tip. The ratio of the thrust component of force to the power, or vertical, force component has been used to develop models for (i) its initial value as a function of feed, (ii) wear, and (iii) tool lifetimes. Predictions of the latter model have been compared with the results of experiments, and with predictions of an extended Taylor model. In all cases, good predictive capability of the model has been demonstrated. It is argued that the models are suitable for use in adaptive control strategies for centre lathe turning.