刀具刃口制备技术研究进展

切削刃口几何形状对刀具的寿命和性能具有决定性作用。适当的刃型可改善刀具的耐磨性,进而提高刀具的寿命及可靠性,改善切削加工的稳定性和工件的质量。切削刃口几何形状包括刃口宏观几何和微观几何及刃口表面形貌。采用合适的刃口制备工艺来获得特定的刃口微观几何和刃口表面形貌,可提高刀具寿命和改善刀具性能。在回顾刃口制备技术和工艺方法、切削刃口表征和测量方法的基础上,讨论了刃口几何形状对刀具耐磨性及刀具寿命和性能的影响。     

AFM检测金刚石刀具锋利度误差分析研究

金刚石刀具是超精密切削的重要工具,其刃口锋利度的好坏对工件切削质量有着直接影响。基于AFM的金刚石刀具刃口锋利度检测是目前的主要方法,但是由于AFM仪器本身、扫描参数设置以及刀具状况、外界干扰等多种影响因素的作用,将导致金刚石刀具纳米级锋利度的检测产生多种误差。以圆弧刃金刚石刀具为测量对象,深入分析各个因素的影响过程,进行了理论分析和实验过程,提出了抑制和修正方法。研究表明,通过上述研究和措施的实施,可以提高锋利度的检测精度,为金刚石刀具高质量评价体系的建立提供理论和方法支持。     

切削刀具刃口形貌对刀具使用寿命的影响

采用喷砂处理切削刀具的刃口获得不同的刃口形貌,采用光学显微镜检测切削过程中刀具刃口磨损状况,采用SEM检测喷砂前后刀具的表面质量,采用工具显微镜测量喷砂后的刃口形貌。在喷枪高度为90、110、120 mm时,分别制备形状因子K值小于1,K值大于1的刃口形貌,在实验中当切削速度为180 m/min,进给量为0.2 mm/r,切削深度为1 mm时,刀具失效时间分别为7 min30 s、10 min50 s、10 min32 s。实验结果表明,在喷枪高度为110~120 mm时,喷砂处理后的刀具使用寿命较好。     

切削刃法剖面曲线刃口微观形貌对切削加工应力的影响

为了研究切削加工时刀具切削刃法剖面不同曲线刃口微观形貌对刀具切削应力和铁屑的影响,采用切削仿真软件Third Wave Advant Edge进行了2D切削仿真试验,分析了不同刃口微观形貌对镍基合金inconel718进行直角自由切削时的切削应力变化,总结了在切削过程中不同刃口微观形貌的刀具应力和接触面应力变化规律以及铁屑卷曲的形成。     

切点约束和探针针尖半径补偿的金刚石刀具刃口钝圆半径求解方法

本文对金刚石刀具刃口钝圆半径求解方法展开研究,以有效提升金刚石刀具刃口锋利度的测量精度。文中分析了原子力显微镜(AFM)扫描探针几何形貌对金刚石刀具刃口锋利度测量结果的影响,并提出了基于切点约束和AFM探针针尖半径补偿的刀具刃口钝圆半径求解方法;讨论了消噪滤波、测量角度误差以及切点分离方法对测量结果的影响;在高精度测量平台上完成了金刚石刀具刃口锋利度测量,并将被测量的刀具用于飞切加工KDP晶体。结果表明:提出的刃口钝圆半径求解方法能够准确求解金刚石刀具的刃口锋利度,测量结果能很好地描述金刚石刀具的刃口锋利程度,可以为金刚石超精密切削加工的选刀和用刀提供有效指导。     

一种基于AFM的金刚石刀具刃口锋利度的检测方法

金刚石刀具刃口纳米级别的锋利度是影响超精密加工表面质量特别是表面微观几何形貌的重要因素.针对目前测量中存在的问题,介绍了一种新的使用原子力显微镜(Atomic Force Microscope,AFM)进行金刚石刀具刃口锋利度检测的方法,该方法首先利用仿射变换进行截面数据提取,然后利用一种基于曲率的算法求出圆弧拟合点,...     

刀具非对称刃口简化模型对切削力影响的研究

目前针对刀具非对称刃口的切削力理论模型甚少，其主要原因在于以往的复杂刃口形貌表征方法无法采用现有的理论进行切削力分析。对此，这里首先在形状因子对刀具刃口对称性描述的基础上对非对称刃口形貌进行表征，其次针对由刀具刃口作用产生的犁耕力，提出刃口简化模型，以简化犁耕力的分析，最后采用有限元仿真与铣削实验对所提出的刃口表征与简化模型进行铣削力验证，结果显示切削力误差较小，从而验证了所提方法的合理性。研究成果对于切削力理论模型的发展具有重要意义。     

超精密加工的三维表面形貌预测

描述并建立了仿真超精密加工的三维表面形貌模型。三维表面形貌模型由切削参数,刀具几何形状及刀具与工件的相对运动来表征,通过将预测的表面粗糙度轮廓线性映射到网格 面元上来生成已加工表面的形貌,实际的加工和测量实验表明,仿真的三维表面形貌和由激光干涉形貌仪测量得到的三维形貌具有很好的相似性。该模型可用来确定如刀具切削运动的迹线,表面波度等表面特征。     

基于ABAQUS的磨粒对刀具刃口钝化的分析

刀具钝化技术通过改变刀具的切削刃微观形貌及轮廓来提高刀具寿命和切削过程的稳定性。根据立式旋转钝化法的特点,采用ABAQUS有限元分析软件建立仿真模型,对单磨粒和多磨粒对刀具刃口的钝化进行模拟,研究刀具钝化过程中磨粒速度、刀具刃口应力、刀具刃口位移和能量等的变化规律,对于提高刀具钝化的效率以及研究刀具刃口钝化机制具有重要的意义。     

钝化参数对刀具刃口钝圆半径影响的研究

刀具刃口钝化通过消除刃口上的微观缺口,改变切削刃的微观形貌,实现增加刀具的寿命,提升刀具的切削性能,使已加工零件获得更好地表面质量的目的。基于立式旋转钝化特点,获得了刀具刃口的运行轨迹。对硬质合金刀具采取立式旋转钝化的方式进行钝化,通过刀具钝化实验,并通过扫描电子显微镜对钝化后的刀具刃口钝圆半径进行测量,研究刀具转速和钝化时间对刀具刃口钝圆半径的影响规律,为优化刀具钝化工艺参数和提高刀具刃口钝化效率提供依据。     

An integrated method for measurement of diamond tools based on AFM

The measurement and evaluation technology of high precision diamond tools is critically important for supporting the ultra-precision machining. In practical cutting process, the edge profile quality of the diamond tool, including sharpness, micro defects, roughness and tip arc waviness, greatly affects the cutting quality. It is very difficult to measure and evaluate the diamond tool edge profile due to the high precision of tool edge profile and complexity of various measurement parameters. In this paper, an integrated method for measurement and characterization of diamond tools is proposed, which is based on an Atomic Force Microscope (AFM) module. Multiple technical indexes of diamond tools are obtained and validated based on the presented research and cutting experiments, and the evaluation model for each technical index is also proposed. The integrated measurement equipment, including an AFM, precision adjustment device and aerostatic bearings, has been established based on the accuracy requirement of measurement parameters. The edge sharpness, micro defects, surface roughness and tip arc waviness have been obtained based on the evaluation model and experimental data. The experimental results show that the measurement accuracy meets the requirements of the comprehensive evaluation of the diamond tool edge profile. The research work will also contribute to the development of ultra-precision machine.     

基于AFM的纳米尺度线宽计量模型及其算法的研究

纳米尺度线宽的测量广泛应用于半导体制造、数据存储、微机电系统等领域。随着制造技术的进步,线宽的极限尺寸也变得越来越小,目前已经缩小至100 nm左右。在这一尺度范围内,由于样本制造技术的限制和测量仪器的影响,目前很难得到准确的测量结果。为了获得样本的真实几何尺寸信息,剔除测量方法和仪器本身对测量结果的影响,建立了一个基于AFM测量技术的线宽计量模型和相应算法。该模型将被测样本的截面轮廓用20个关键点分成5个部分共19段,用基于最小二乘的直线来拟合实际轮廓。应用该模型和算法可以分别得到单刻线轮廓拟合前后的顶部线宽b_T、b_(TF),中部线宽b_M、b_(MF),底部线宽b_B、b_(BF),左右边墙角A_L、A_R,以及高度h_。使用NanoScope Ⅲa型AFM对一个单晶硅(Si)线宽样本进行了测量,测量结果表明该模型和算法可以满足纳米尺度线宽计量的基本要求。     

An edge reversal method for precision measurement of cutting edge radius of single point diamond tools

A method, which is referred to as the edge reversal method, is proposed for precision measurement of the cutting edge radius of single point diamond tools. An indentation mark of the cutting edge which replicates the cutting edge geometry is firstly made on a soft metal substrate surface. The cutting edge of the diamond tool and its indentation mark, which is regarded as the reversal cutting edge, are then measured by utilizing an atomic force microscopy (AFM), respectively. The cutting edge radius can be accurately evaluated through removing the influence of the AFM probe tip radius, which is comparable to the cutting edge radius, based on the two measured data without characterization of the AFM probe tip radius. The results of measurement experiments and uncertainty analysis are presented to demonstrate the feasibility of the proposed method.     

A Gaussian process and image registration based stitching method for high dynamic range measurement of precision surfaces

Optical instruments are widely used for precision surface measurement. However, the dynamic range of optical instruments, in terms of measurement area and resolution, is limited by the characteristics of the imaging and the detection systems. If a large area with a high resolution is required, multiple measurements need to be conducted and the resulting datasets needs to be stitched together. Traditional stitching methods use six degrees of freedom for the registration of the overlapped regions, which can result in high computational complexity. Moreover, measurement error increases with increasing measurement data. In this paper, a stitching method, based on a Gaussian process, image registration and edge intensity data fusion, is presented. Firstly, the stitched datasets are modelled by using a Gaussian process so as to determine the mean of each stitched tile. Secondly, the datasets are projected to a base plane. In this way, the three-dimensional datasets are transformed to two-dimensional (2D) images. The images are registered by using an (x, y) translation to simplify the complexity. By using a high precision linear stage that is integral to the measurement instrument, the rotational error becomes insignificant and the cumulative rotational error can be eliminated. The translational error can be compensated by the image registration process. The z direction registration is performed by a least-squares error algorithm and the (x, y, z) translational information is determined. Finally, the overlapped regions of the measurement datasets are fused together by the edge intensity data fusion method. As a result, a large measurement area with a high resolution is obtained. A simulated and an actual measurement with a coherence scanning interferometer have been conducted to verify the proposed method. The stitching result shows that the proposed method is technically feasible for large area surface measurement.     

Investigation of diamond cutting tool lapping system based on on-machine image measurement

The profile tolerance of diamond cutting tool??s edge is one of the key factors in affecting machining accuracy. With the development of ultra-precision machining technology for optical free-form surfaces and optical microstructures, the demand for high-precision round nose diamond cutting tools is increasing. In this study, an on-machine image processing approach is applied to cutting edge geometry truing process, and profile data of cutting edge in sub-pixel precision is acquired using a series of image processing methods. According to the profile captured, the deviation from an ideal cutting edge is calculated and feedbacked to the controller. The lapping system is employed to lap the cutting edge pertinently using the deviation and the corresponding position captured, and the round edge of high accuracy is obtained efficiently. This method can avoid the error caused by the process of refixturing for offline measurement in the traditional lapping method of diamond cutting tool and reduce the influence of human factors. A truing experiment for cutting edge of the monocrystal diamond cutting tool is carried out at the developed lapping system based on on-machine image measurement, and round cutting edge of profile tolerance less than or equal to ±0.5???m is achieved.     

Nanometer edge profile measurement of diamond cutting tools by atomic force microscope with optical alignment sensor

This paper describes an atomic force microscope (AFM) based instrument for nanometer edge profile measurements of diamond cutting tools. The instrument is combined with an AFM unit and an optical sensor for alignment of the AFM probe tip with the top of the diamond cutting tool edge in the submicrometer range. In the optical sensor, a laser beam from a laser diode is focused to generate a small beam spot with a diameter of approximately 10 μm at the beam waist, and then received by a photodiode. The tool edge top and the AFM probe tip are brought to the center of the beam waist, respectively, through monitoring the variation of the photodiode output. To reduce the influence of the electronic noise on the photodiode output so that the positioning resolution can be improved, a modulation technique is employed that modulates the photodiode output to an AC signal by driving the laser diode with a sinusoidal current. Alignment experiments and edge profile measurements are carried out.     

Three-dimensional profile stitching measurement for large aspheric surface during grinding process with sub-micron accuracy

A novel measurement method is proposed to realize three-dimensional (3D) profile stitching for large aspheric surface. The proposed method is based on the multiple sub-regions stitching technology applying a four-axis fixture and a commercial small-range profiler. The partition of sub-regions is due to the effective profiler’s range and the characteristic parameters of aspheric surface, and the measurement for each sub-region within the profiler’s range is achieved through the fixture to translate and rotate the aspheric surface. Then a stitching algorithm including the multi-body theory, the invariability of curvature radiuses and the least square principle is established to reconstruct the full 3D profile. Simulations of multiple sub-regions stitching for different aspheric surfaces are performed to predict the stitching accuracy of proposed method and analyze the influence of alignment errors in Y direction caused by the rotation error along Z direction (Δβ_w,g). The stitching accuracy of proposed method is verified by measuring the 3D profile of an off-axis parabolic surface and an axisymmetric aspheric surface. The experimental standard deviations of stitching errors are 0.16 μm and 0.42 μm, which are less than the form errors of aspheric surface during grinding process. The results show that the proposed method achieves 3D profile stitching for large aspheric surface with sub-micron accuracy.     

A new method for the characterisation of rounded cutting edges

The influence of the cutting edge micro geometry on cutting process and on tool performance is subject of several research projects. Recently published papers focus on optimising the cutting edge rounding. The results are partly inconsistent. Unfortunately, no international standard yet exists to properly describe the cutting edge micro geometry. This is seen as the root cause for detected discrepancies. To develop a common understanding for the influence of rounded cutting edges, it is indispensable to use the same basis to characterise the edge profile. This paper gives a review on existing characterisation methods, analyses the difficulties in their application and discusses different modelling ideas to describe the cutting edge profile. Based hereon, a new algorithm and geometrical parameterisation of the cutting edge is proposed, which reduces uncertainties and difficulties in the application of currently available methods. The proposed method considers measurement uncertainties and is robust against form errors and creates thus the basis required for the study of the influence of rounded cutting edges.     

Measurement of the geometric features of a cutting tool edge with the aid of a digital image processing technique

For the further development of new machining systems such as flexible manufacturing systems (FMS), this paper reports on a new measuring system developed for the multi-purpose understanding of the geometric features of cutting tool edges having serious influences on the machining outputs. In this system, to detect three-dimensional (3D) features of the toolface and tool flank only from the two-dimensional (2D) microscopic observation of the toolface and to describe an overall 3D geometric feature of the tooledge as a digital 2D image as well as to enable inexpensive system development, two convenient measuring principles are used. These are the scanning optical section method for the toolface contour mapping and the cutting edge profile comparison method for the flank wear landwidth estimation. Based on these, experimental hardware was arranged and various processing softwares were developed. They were applied to an observation of the cutting edge wear development in some cylindrical turning experiments, to show that various effective cutting edge parameters could be easily extracted from the integrated toolface image recorded, and that sufficient accuracy and resolution for practical use could be obtained.