Tool path generation of ultra-precision diamond turning: A state-of-the-art review

With the increasing market demand for optical complex surface parts,the application of multi-axis ultraprecision single-point diamond turning is increasing.A tool path generation method is very important to decrease manufacturing time,enhance surface quality,and reduce cost.Compared with the tool path generation of the traditional multi-axis milling,that of the ultra-precision single-point diamond turning requires higher calculation accuracy and efficiency.This paper reviews the tool path generation of ultra-precision diamond turning,considering several key issues:cutter location(CL)points calculation,the topological form of tool path,interpolation mode,and G code optimization.

INFLUENCE OF WHEEL STRUCTURAL PARAMETERS ON MACHINING ACCURACY OF ULTRA-PRECISION PLANE HONING

A new idea for designing wheel patterns is presented so as to solve theproblems about machining accuracy of workpiece and wear of honing wheel in ultra-precision planehoning. The influence factors on motion principle and pattern structures are analyzed andoptimization machining parameters are obtained. By calculating effective cutting length on thesurface of workpiece cut by wheel's abrasive and the orbit of one point on the surface of workpiececontacting with wheel, the wear coefficient of different kinds of wheels and accuracy coefficient ofworkpiece machined by corresponding wheels are obtained. Furthermore, the simulation results showthat the optimal pattern structure of wheel turns out to have lower wheel wear and higher machiningaccuracy.

Prediction of cutting force in ultra-precision machining of nonferrous metals based on strain energy

The effects of the nonuniform cutting force and elastic recovery of processed materials in ultra-precision machining are too complex to be treated using traditional cutting theories,and it is necessary to take account of factors such as size effects,the undeformed cutting thickness,the tool blunt radius,and the tool rake angle.Therefore,this paper proposes a new theoretical calculation model for accurately predicting the cutting force in ultra-precision machining,taking account of such factors.The model is first used to analyze the material deformation of the workpiece and the cutting force distribution along the cutting edge of a diamond tool.The size of the strain zone in different cutting deformation zones is then determined by using the distribution of strain work per unit volume and considering the characteristics of the stress distribution in these different deformation zones.Finally,the cutting force during ultra-precision machining is predicted precisely by calculating the material strain energy in different zones.A finite element analysis and experimental data on ultra-precision cutting of copper and aluminum are used to verify the predictions of the theoretical model.The results show that the error in the cutting force between the calculation results and predictions of the model is less than 14%.The effects of the rake face stress distribution of the diamond tool,the close contact zone,and material elastic recovery can be fully taken into account by the theoretical model.Thus,the proposed theoretical calculation method can effectively predict the cutting force in ultra-precision machining.

Design and Manufacturing of Ultra-Hard Micro-Milling Tool

Based on the study of existing typical micro-milling tools and the actual demand for micro-milling tools, the P3 design principle and design flow for ultra-hard micro-milling tool were introduced to give basic guidance for the optimization of micro-milling tools. Then, according to the P3 design flow, the manufacturing process of polycrystalline diamond(PCD) micro-milling tool was proposed, and the PCD micro-milling tool with diameter of 0.5 mm was developed. Finally, the micro-milling test on the slot was carried out to study the milling performance of PCD micromilling tool.

Heat Resistant Properties of Some Elements-Incorporated Diamond-Like Carbon Films and Their Trial Applications for Micro End Mill Coatings

In this article, the results obtained from a study carried out on the some elements-incorporated diamond-like carbon (DLC) films are reported. All the films were deposited using plasma-based ion implantation (PBII) technique. The deposited films were annealed at 400℃, 650℃ and 900℃ in an air atmosphere for 1 hour. The effects of adding hydrogen, silicon/oxygen and silicon/nitrogen into the DLC film on chemical composition, friction coefficient and corrosion resistance were investigated. The films coated micro end mills performance was also assessed. The results indicate that all the films showed almost constant atomic contents of C, Si, O and N until annealing at 400℃. However, the films were completely destroyed at 650℃ with the increased Si and O contents, while the C content decreased. The incorporation of silicon/oxygen and silicon/nitrogen into the DLC exhibited lower values of friction coefficients than the hydrogenated DLC (DLC and H-DLC) before and after annealing at 400℃, whereas all the films presented the same values of friction coefficients after annealing at 650℃ due to the completely destroy of the films. Furthermore, the incorporation of silicon/nitrogen into the DLC also exhibited better corrosion resistance and unbroken micro end mills performance on their surfaces. Thus, the incorporation of silicon/nitrogen into the DLC film can be considered beneficial in improving the micro end mills performance.

Simulation and experiment analysis on thermal deformation of tool system in single-point diamond turning of aluminum alloy

The aim of this work is to simulate thermal deformation of tool system and investigate the influence of cutting parameters on it in single-point diamond turning(SPDT) of aluminum alloy. The experiments with various cutting parameters were conducted. Cutting temperature was measured by FLIR A315 infrared thermal imager. Tool wear was measured by scanning electron microscope(SEM). The numerical model of heat flux considering tool wear generated in cutting zone was established. Then two-step finite element method(FEM) simulations matching the experimental conditions were carried out to simulate the thermal deformation. In addition, the tests of deformation of tool system were performed to verify previous simulation results. And then the influence of cutting parameters on thermal deformation was investigated. The results show that the temperature and thermal deformation from simulations agree well with the results from experiments in the same conditions. The maximum thermal deformation of tool reaches to 7 μm. The average flank wear width and cutting speed are the dominant factors affecting thermal deformation, and the effective way to decrease the thermal deformation of tool is to control the tool wear and the cutting speed.

Ultra-precision Machining of Micro-step Pillar Array Using a Straight-Edge Milling Tool

Ultra-precision machining has been well known as a very precise and effective way to prototype and fabricate different types of components with microstructures.In this paper,an ultra-precision micro-milling method has been presented to produce a micro-step pillar array as an embossing mold for semiconductor application.Theoretical analysis on machining mechanics indicates that work material property,machining strategy,and cutting tool geometry largely afFect machining distortion on the machined microstructure.Experimental investigation has been conducted on micromachining of the micro-step pillar array using different types of cutting tools and work materials.Experimental results demonstrate that the material property,cutting tool edge radius,and cutting force play a significant role in the machined micro-structure accuracy and surface finish,while grain boundary of brass has no significant effect on the micro-milling performance.The best outcome among the tests done is achieved when using brass as work material and cutting with a straight-edge single crystalline diamond tool.The main reasons to achieve this outcome are based on:the brass material having a higher elastic modulus and the diamond tool having a smaller cutting edge radius,which contributes to better machinability of brass.One micro-step pillar array has been successfully obtained with very precise feature and dimensional accuracy using brass work material and single-crystal diamond tool.It is believed that the outcomes of this study would largely benefit the research community and end-users.

新型CVD金刚石涂层刀具铣削高性能各向同性石墨研究

利用自主研发的新型CVD金刚石复合涂层刀具对自行研制的高密高强各向同性石墨材料进行了铣削加工试验,对比测试了新型CVD金刚石复合涂层刀具与PCD刀具的切削性能。试验结果表明,PCD刀具铣削加工25min其后刀面磨损已超过磨钝标准0.3 mm,新型CVD金刚石复合涂层刀具加工到45 min时,其后刀面磨损量仅为0.25 mm,这说明新型CVD金刚石复合涂层刀具高速铣削石墨时表现出良好的耐磨性和使用寿命,可以适应高性能各向同性石墨的加工需求。铣削加工试验还发现新型CVD金刚石复合涂层刀具加工的石墨表面质量在初期不如PCD刀具,但在更长时间加工情况下,其加工表面质量优于PCD刀具。

增材制造钛合金的微铣削加工试验

增材制造(Additive manufacturing,AM)技术制备的钛合金部件在航空航天领域具有广泛的用途,对增材制造钛合金精密零部件而言,铣削、抛光等后处理加工是必不可少的工序。本文选用聚晶金刚石(Polycrystalline diamond,PCD)微铣刀对锻造钛合金、激光选区熔化(Selective laser melting,SLM)技术制备的未经过热处理和经过热处理的钛合金进行微铣削试验,研究了3种不同制造工艺的钛合金材料的微铣削加工性能。结果表明:SLM-热处理钛合金的铣削力最大,这与其材料硬度最高有关。微铣削过程中,所有钛合金材料的逆铣侧顶端毛刺尺寸均要大于顺铣侧顶端毛刺尺寸。在不同制造工艺的钛合金材料中,SLM-钛合金生成的顶端毛刺宽度最小,这与其塑性最差有关。SLM-热处理钛合金获得的表面质量最好,这不仅与材料的硬度和塑性有关,同时还受到孔隙度的影响。

Cutting force and its frequency spectrum characteristics in high speed milling of titanium alloy with a polycrystalline diamond tool

In this paper, a series of experiments were performed by high speed milling of Ti-6.5Al-2Zr-1Mo-1V (TA15) by use of polycrystalline diamond (PCD) tools. The characteristics of high speed machining (HSM) dynamic milling forces were investi- gated. The effects of the parameters of the process, i.e., cutting speed, feed per tooth, and depth of axial cut, on cutting forces were studied. The cutting force signals under different cutting speed conditions and different cutting tool wear stages were analyzed by frequency spectrum analysis. The trend and frequency domain aspects of the dynamic forces were evaluated and discussed. The results indicate that a characteristic frequency in cutting force power spectrum does in fact exist. The amplitudes increase with the increase of cutting speed and tool wear level, which could be applied to the monitoring of the cutting process.

Study on 6-DOF active vibration-isolation system of the ultra-precision turning lathe based on GA-BP-PID control for dynamic loads

The vibration disturbance from an external environment affects the machining accuracy of ultra-precision machining equipment.Most active vibration-isolation systems(AVIS)have been developed based on static loads.When a vibration-isolation load changes dynamically during ultra-precision turning lathe machining,the system parameters change,and the efficiency of the active vibration-isolation system based on the traditional control strategy deteriorates.To solve this problem,this paper proposes a vibration-isolation control strategy based on a genetic algorithm-back propagation neural network-PID control(GA-BP-PID),which can automatically adjust the control parameters according to the machining conditions.Vibration-isolation simulations and experiments based on passive vibration isolation,a PID algorithm,and the GA-BP-PID algorithm under dynamic load machining conditions were conducted.The experimental results demonstrated that the active vibration-isolation control strategy designed in this study could effectively attenuate vibration disturbances in the external environment under dynamic load conditions.This design is reasonable and feasible.

基于金刚石涂层的石墨铣刀磨损特性研究

为深入分析金刚石涂层铣刀加工石墨的磨损机理以及对表面粗糙度的影响,采用单因素实验对石墨进行铣削加工,通过超景深显微镜对刀具的端齿进行测量,同时采用三维测量仪对刀具的周刃进行轮廓检测,并采用手持式粗糙度检测仪对加工表面进行粗糙度检测。结果表明:石墨铣削加工中,刀具的磨损形式以磨粒磨损为主,随着切削距离的增加,刀具端齿磨损不断加剧,出现从涂层脱落到刃口崩缺的变化,而周刃刃口轮廓出现较大的磨损;工件表面粗糙度在垂直进给方向上随着刀具磨损和切削距离的增加而增大。

金刚石涂层刀具高速铣铝合金平面切削毛刺研究

采用热丝CVD法制备纳米与微米金刚石薄膜涂层刀具,利用场发射扫描电镜表征其薄膜表面形貌。用已制备的CVD金刚石涂层刀具,在无润滑干切条件下高速顺、逆端铣铝合金平面,研究CVD金刚石涂层刀具切削时的棱边毛刺特点与大小;并对纳米金刚石涂层刀具高速顺铣切削工艺参数进行正交试验,探究取得少无切削毛刺的切削参数与切削工艺。结果表明:工件铣削后棱边毛刺分布不均匀,顺铣毛刺稀疏,尺寸较小,其中纳米金刚石涂层刀具顺铣棱边毛刺高度平均值为32.08μm,仅为微米金刚石涂层刀具顺铣毛刺高度的46.5%。纳米金刚石涂层刀具高速顺铣平面,对棱边毛刺影响最大的是v_(c),其次为v_(f),ae的影响最小,最优参数组合为a_(e)=4 mm、v_(f)=2000 mm/min、v_(c)=400 m/min,铣削后毛刺高度平均值为21.29μm。当金刚石涂层刀具端铣铝合金平面时,为取得较小的棱边毛刺,优选纳米金刚石涂层刀具,采用顺铣棱边的切削方式与切削工艺,以及相应的高速切削参数。

基于MD模拟的低能FIB辐照金刚石靶材亚表层损伤形成机理研究

聚焦离子束(focused Ion beam,FIB)作为一种用于金刚石微铣刀的特种加工方式,其引发的损伤程度直接关联到刀具的加工性能和寿命。课题组采用LAMMPS软件进行分子动力学(Molecular Dynamics,MD)模拟,结合SRIM软件的分析结果,探究单晶金刚石亚表层损伤的形成机理和入射离子能量对损伤深度和范围的影响。模拟结果表明:随着入射离子能量的提升,离子束在材料内的渗透深度及引起的非晶层和点缺陷损伤均有所增加;进一步的研究发现损伤形成过程中材料局部温度的上升可能诱发自退火现象,且与离子入射能量成正比,该现象对于理解聚焦离子束加工引起的损伤有着至关重要的意义;而势能的变化与损伤形成之间的显著对应关系揭示了第一邻近原子的势能明显高于第二邻近原子,进而高于Other类型原子,这一发现有助于深入理解损伤形成的微观过程。因此,精确控制入射能量是实现金刚石材料高精度聚焦离子束加工的关键,且对自退火效应和势能变化的研究对损伤监控与控制同样重要。

一种牙科单层高温钎焊金刚石砂轮的研制

概述了金刚石工具在牙科领域的应用和发展状况。针对传统电镀砂轮的缺点 ,在国内外钎焊金刚石研究的基础上 ,采用真空炉内高温钎焊的方法 ,以NiCr1 3P9合金为钎料 ,配以少量Cr粉 ,在高温加压的条件下研制了用于牙科CERECCAD CAM系统的专用单层高温钎焊金刚石砂轮 ,并初步探索了高温钎焊金刚石砂轮的制作工艺、适当的钎焊温度及合理的升降温曲线。扫描电镜观察显示在金刚石的周围有银白色的合金包绕 ,X衍射分析发现有Cr3C2 生成 ,表明在 95 0℃的钎焊温度下实现了金刚石与钢基体间的高结合强度连接。磨削实验亦证实金刚石确有高的把持强度 。

SiC_p/Al复合材料高速铣削加工表面质量及切屑形成机制

使用聚晶金刚石(PCD)刀具,对碳化硅颗粒增强铝基复合材料(SiCp/Al)进行高速铣削加工,研究了加工表面质量及切屑的形成机制。结果表明:刀具进给波纹、工件材料塑性侧流、刀具-工件相对振动和增强颗粒去除过程留下的孔洞、微裂纹、基体撕裂等是SiCp/Al复合材料高速铣削加工表面的主要形成机制;增大切削速度、使用冷却液、降低增强颗粒体积分数、减小增强颗粒尺寸均有助于提高加工表面质量;切屑形态为不均匀锯齿状,增强颗粒体积分数、热处理状态等对切屑形成有显著影响,绝热剪切、孔洞/微裂纹动态形成和扩展是切屑的主要形成机制。

活化烧结对金刚石增强型硬质合金复合齿性能的影响

在金刚石增强型硬质合金复合齿基体中球磨添加不同量红磷,比较相应的金刚石增强型硬质合金基体的性能,确定添加(质量分数)0.3%P的复合齿基体性能最好;同时采用化学镀Ni-P合金添加P结合球磨添加0.1%P的方式,其超硬复合齿基体力学性能及复合齿的磨耗比、抗冲击功远远优于单纯球磨添加0.3%P方式超硬复合齿的性能。说明为了实现金刚石增强型硬质合金复合齿的活化烧结方式,磷元素最优的添加方式是化学镀结合球磨的添加方式。

数控加工石材时加工参数对金刚石铣刀耐磨性影响实验研究

为确定合理的加工参数,提高加工效率,采用正交法设计实验参数,在数控机床上研究了铣削石材时各加工参数对金刚石刀具磨损量的影响。金刚石铣刀采用热压成型法制造,金刚石铣刀磨损表面采用Leica MZ95体式显微镜分析。结果表明,影响金刚石铣刀磨损量的主要加工参数是切割深度,其次是进给速度,刀具主轴转速影响最小。刀具底面的磨损比侧面严重,底面金刚石主要以脱落为主,侧面金刚石磨损以冲击破碎为主。

金刚石涂层立铣刀与PCD立铣刀切削铝合金性能研究

目的研究金刚石涂层立铣刀和PCD立铣刀切削铝合金时,铝合金表面粗糙度以及刀具的使用寿命。方法通过实验比较1μm、5μm金刚石涂层四刃立铣刀和PCD立铣刀在高速干式切削条件下切削铝合金的性能,并通过走刀距离比较不同状态刀具的使用寿命以及在走刀过程中的粘刀情况,用表面粗糙度测量仪测量加工的铝合金表面粗糙度。结果 1μm、5μm金刚石涂层立铣刀加工铝合金失效距离分别为25 m、75 m,PCD立铣刀加工铝合金96 m后失效;1μm、5μm金刚石涂层立铣刀切削铝合金表面粗糙度平均值分别为1.07μm、1.10μm,PCD立铣刀切削铝合金表面粗糙度平均值为0.80μm。结论 5μm金刚石涂层立铣刀是1μm金刚石涂层立铣刀寿命的5倍,PCD立铣刀使用寿命最长;1μm、5μm金刚石涂层立铣刀切削铝合金表面较PCD立铣刀粗糙,在相同切削环境下切削铝合金时,PCD立铣刀使用寿命较金刚石涂层立铣刀提高,且在抑制粘刀方面效果十分明显。

金刚石铣刀加工花岗石磨损规律的试验研究

本文以金刚石圆柱成形铣刀在SPEED3石材加工中心上加工花岗石台板面边缘曲线为对象进行试验 ,分析研究刀具宏观几何尺寸参数 (直径、质量、圆柱度 )的变化量与工件材质及其去除量间的关系 ,探询刀具磨损规律。通过利用不同构成和工艺参数的刀具加工两种花岗石的对比实验 ,得出了刀具几何参数与工件材料去除量关系的变化曲线。据此 ,可分析计算刀具直径的磨损变化规律、预测刀具寿命 。