表面测量与分析在调控加工中的应用

对超精车削加工中得到的表面进行表面仿真分析.通过分析其表面空间频谱,确定表面微观形貌特征与加工参数、切削振动之间的关系,为调控加工过程提供理论依据.     

车削粗糙表面的特征解耦与形貌仿真

结合机床运动学与切削理论,对车削加工过程中表面形貌的影响因素进行了归类概括。基于复杂叠加信号解耦的思想,针对已加工成型的车削表面,采用频谱分析将形貌信号按照波长关系进行划分,得到加工因素对各波段信号幅值的影响规律。解决了直接分析多种加工因素耦合所引起考虑参数缺失与复杂信号分量叠加无法直接解耦的难题。针对相对精细的粗糙表面信号直接提取难度大的特点,按照加工表面粗糙度数值的大小,将粗糙表面划分为粗糙与精细两种类型。从幅值梯度较大,相对粗糙的加工表面形貌成分提取入手,得到各加工成分信息对实际形貌的影响规律。采用相应信号成分对各加工因素信号成分进行代替,实现粗糙表面形貌的提取与仿真。继而将分析得到的信号成分影响规律应用于相对精细粗糙表面信号的分析,最终实现从粗糙表面信号到精细表面信号成分的表征与解耦,为相对精细粗糙表面形貌的预测与仿真提供一种新的方法与思路。最后,结合表面信号特征提取的结果,实现了对车削粗糙表面形貌的仿真,为车削加工表面形貌的预测与车削粗糙表面接触分析提供了实用性的数字模型。     

超精密车削表面微观形貌的几何建模与仿真研究

在综合考虑刀具几何参数，刀具振动和最小切削厚度等因素对已加工表面形貌影响的前提下编写了表面微观形貌的仿真程序，在仿真时把一个随机振动信号成功地叠加在理论表面粗糙度中。提出一种建立圆弧刃金刚石车刀超精密车削表面粗糙度模型的新方法。结果表明，仿真得到的表面微观形貌，能够比较正确地反映出超精密加工将要获得的表面轮廓。     

超精密车削时切屑形成及表面微观形貌形成机理的研究

在亚微米级CNC超精密车床上进行了单晶金刚石刀具切削试验 ,根据试验结果分析了切屑形成机理和最小切削厚度与表面粗糙度之间的关系 ,建立了加工表面微观形貌的几何模型。研究结果表明 :通过计算最小切削厚度值可预测金刚石车削加工可获得的表面粗糙度值。     

超洁净PTFE车削加工切削参数对表面形貌及粗糙度变化影响

聚四氟乙烯(PTEE)是超洁净流控元件的主要材料之一。针对聚四氟乙烯机械加工后的表面粗糙度问题,从改变进给量及车刀材料选择和切削液是否使用的角度探究机械加工PTFE表面形貌的形成机理,发现了随着车刀停留时间的增加,PTFE表面粗糙度迅速降低并最终保持在一个稳定值,而车刀材料和是否使用切削液也对PTFE机械加工后的表面形貌有非常显著的影响;通过共聚焦激光显微镜和原子力显微镜(AFM),在不同的尺度下观察了加工后PTFE的表面形貌,为从微观层面解释聚四氟乙烯机械加工后表面形貌的形成提供了直观的观测结果,从而揭示了表面形貌与车削加工参数的映射关系,并为氟塑料车削工艺的优化提供了指导性依据。     

应用AFM研究单晶硅、锗的超精密车削表面微观形貌

单晶硅、锗的超精密车削表面存在明暗相间的分布特征。本文主要对该现象的产生原因进行了研究,认为车削过程中垂直解理面的切削分力的连续变化是产生这种分布特征的主要因素,用AFM对加工表面微观形貌的检测结果充分地证明了该观点的正确性     

超精密加工表面微观形貌非接触在线检测系统

介绍了专门应用于超精密车档在线检测加工表面微观形貌的检测系统。一种新式高分辨率同轴式激光逻辑设计仪与超精密车床的有机结合,突破了传统的必须卸下工件才能对其进行检测的限制,实现了加工与检测的一体化,达到了检测真正服务于加工的工作原理。实验结果表明,在利用超精密精密气浮导轨作为激光轮廓仪工作台的条件下,测量车削加工表面微观形貌时,在高度方向上的分辩率按国际惯用的均方值表示已倨于０．１ｎｍ。     

超声振动车削金属后表面物理性能变化的研究

机械切削加工制品,最后精加工形成的零件表面质量对其使用性能的影响至关重要,历来受到重视。z向分离型超声振动车削(以下简称振动车削)的表面粗糙度和微观几何形貌国内外已作过大量研究。但是研究振动车削后表层材料物理性能的变化尚少。因此,我们从宏观残余应力和加工硬化两方面对振动车削的表层物理变化进行了研究。并用振动车削加工的     

单点金刚石车削辊筒表面V型螺旋槽表面形貌仿真与试验研究

提出了辊筒表面车削V型沟槽的一种螺旋式加工方法并进行了车削试验。对车削系统进行了仿真模拟,得出了刀架Z轴的输入输出曲线以及V型沟槽的理论形貌与实际形貌,计算出表面粗糙度R_a=0.311μm,与试验检测结果 R_a=0.389μm相差不大。验证了车削系统仿真模型的有效性,进一步证明了加工方法的可行性。     

考虑耕犁的超声磨削表面微观形貌建模与预测

超声磨削加工在难加工材料领域得到广泛应用,超声辅助磨削过程中,超声振动参数对磨削后的表面微观形貌具有重要影响,因此,为了在加工前对超声加工后的表面微观形貌进行预测,以优化加工参数。提出一种考虑耕犁的超声磨削表面微观形貌建模与预测方法。假设磨粒为球形,磨粒直径与间距服从高斯分布,给出砂轮形貌的数值生成方法;根据超声磨削运动学,建立考虑磨粒实时切削深度与耕犁影响的三维运动轨迹方程;在此基础上,提出超声磨削表面微观形貌生成的区域逼近求解算法,进而给出超声磨削表面微观形貌生成模型,模拟出超声磨削的三维表面微观形貌。通过试验分别从表面微观形貌的轨迹纹理、表面粗糙度数值两个方面对超声磨削表面微观形貌的模型的正确性进行了验证。     

金刚石车削单晶锗的试验研究

论述金刚石车削单晶锗的加工表面质量，重点研究影响加工表面质量的因素。试验结果表明，采用小进给量和大负前角对于用单点金刚石车削的方法在单晶锗材料上制取优质加工表面是至关重要的。     

Machining of austenitic stainless steels using CVD multi-layer coated cemented carbide tools

This paper presents the results of experimental work in dry turning of austenitic stainless steels (AISI 304 and AISI 316) using CVD multi-layer coated cemented carbide tools. The turning tests were conducted at four different cutting speeds (120, 150, 180 and 210 m/min) while feed rate and depth of cut were kept constant at 0.16 mm/rev and 1 mm, respectively. The cutting tools used were TiC/TiCN/TiN and TiCN/TiC/Al₂O₃ coated cementide carbides. The influences of cutting speed, cutting tool coating top layer and workpiece material were investigated on the machined surface roughness and the cutting forces. The worn parts of the cutting tools were also examined under scanning electron microscope (SEM). The results showed that cutting speed significantly affected the machined surface roughness values. With increasing cutting speed, the surface roughness values decreased until a minimum value is reached beyond which they increased.     

奥贝可锻铸铁己加工表面完整性研究

在切削加工奥贝可锻铸铁时，由于其金相组织中存在20％～30％的残余奥氏体，极易造成已加工表面的加工硬化以及在刀具切削刃附近产生粘结物，严重影响已加工表面完整性。本文通过大量切削试验，得出四种刀具材料在不同切削用量条件下对奥贝可锻铸铁已加工表面完整性的影响规律，观察并分析了切削过程中出现的一些异常现象。     

Investigating the Machinability of Al–Si–Cu cast alloy containing bismuth and antimony using coated carbide insert

Surface roughness and cutting force are two key measures that describe machined surface integrity and power requirement evaluation, respectively. This investigation presents the effect of melt treatment with addition of bismuth and antimony on machinability when turning Al–11%Si–2%Cu alloy. The experiments are carried out under oblique dry cutting conditions using a PVD TIN-coated insert at three cutting speeds of 70, 130 and 250 m/min, feed rates of 0.05, 0.1, 0.15 mm/rev, and 0.05 mm constant depth of cut. It was found that the Bi-containing workpiece possess the best surface roughness value and lowest cutting force due to formation of pure Bi which plays an important role as a lubricant in turning process, while Sb-containing workpiece produced the highest cutting force and highest surface roughness value. Additionally, change of silicon morphology from flake-like to lamellar structure changed value of cutting force and surface roughness during turning.     

Anisotropy of machined surfaces involved in the ultra-precision turning of single-crystal silicon—a simulation and experimental study

A new method was proposed for simulating the anisotropic surface quality of machined single-crystal silicon. This represents the first time that not only the mechanical properties of silicon, but also the crystal orientation, which is closely linked to the turning process, have been given consideration. In this paper, the crystallographic relationship between machined crystal planes and slip planes involved in ultra-precision turning was analyzed. The elasticity, plasticity, and brittleness properties of silicon in different crystal orientations were calculated. Based on the brittle–ductile transition mechanism of ultra-precision turning of single-crystal silicon, the orientation dependence of the surface quality of (111), (110), and (100) crystal planes were investigated via computer simulation. According to the simulation results, the surface quality of all machined planes showed an obvious crystallographic orientation dependence while the (111) crystal plane displayed better machinability than the other planes. The anisotropic surface properties of the (111) plane resulted from the continuous change of the cutting direction, which causes a change of actual angle between the slip/cleavage plane and machined plane. Anisotropic surface properties of planes (100) and (110) result from anisotropy of mechanical properties and the continuous changes of the cutting direction, causing the actual angle between slip/cleavage plane and machined plane to change simultaneously. A series of cutting experiments were carried out on the (111) and (100) crystal planes to verify the simulation results. The experimental results showed that cutting force fluctuation features and surface roughness are consistent with the anisotropy characteristics of the machined surface as revealed in simulation studies.     

奥-贝球墨铸铁加工表面质量的试验研究

用试验的方法研究了奥－贝球墨铸铁的加工表面形态、已加工表面粗糙度，分析了切削用量和刀具几何角度对加工表面粗糙度的影响．结果表明，已加工表面质量与刀具切削刃不平整及材料组织有关。为提高加工表面质置，必须优选切削参数，重视刀具磨损、后刀面粗糙度及工件材料组织的缺陷。     

How to diamond turn an elliptic half-shell?

In this research note we are introducing a new slow slide servo (SSS) turning technique which enables fast diamond machining of deep aspheric surfaces which otherwise can only be machined by ball-end milling, if at all. The key idea is to execute the servo motion not only parallel to the axis of rotation, which is the standard mode implemented in commercial SSS software, but in a plane incorporating both directions parallel and perpendicular to the rotational axis. In this way the risk of collisions in non-circular turning between the tool shaft and the machined surface can be reduced significantly. Moreover, when a 180° contour is machined, the acceleration of the servo slide will not increase indefinitely. After a review of the standard SSS turning technique we will outline the generalized SSS concept and demonstrate its applicability by diamond turning of an elliptic half-shell on a commercial diamond turning lathe.     

The effects of microalloyed steel pre-heat treatment on microstructure and machinability

An extensive study was performed in finish turning of the following microalloyed steels: as received (14.3 HRc), water-cooled (44.9 HRc), air-cooled (14.41 HRc) and furnace-cooled (9.1 HRc). The turning tests were carried out using multi-layer coated cemented carbide tools at four different cutting speeds (60, 90, 120, and 150 m/min) while feedrate and depth of cut were kept constant at 0.1 mm/rev and 1 mm, respectively. The influences of workpiece microstructure and cutting speed on cutting forces and workpiece surface roughness were investigated. The worn parts of the cutting tools were also examined under a scanning electron microscope (SEM). The results showed that cutting speed significantly affected the machined surface roughness values. However, cutting forces were not influenced significantly by workpiece microstructure and cutting speed except for water cooled specimen.     

影响超精密车削表面粗糙度几种主要因素分析

论述了影响超精密车削表面粗糙度的几种主要因素,详细分析了刀具几何形状、最小切削厚度、不规则的金属变形、切削用量、振动等因素对加工表面粗糙度的影响,为超精密车削加工表面质量的控制提供了依据。