金刚石精细切削黑色金属研究

一、前言金刚石切削加工技术作为超精密加工的重要组成部分，广泛用于有色金属及一些复合材料的加工。但金刚石不能加工黑色金属，原因在于金刚石是碳同素异性体，切削黑色金属时，两种材料的碳原子相互摩擦、渗透，形成很强的粘结力而粘结，最终刀具的粘结区被黑色金属粘附过去，出现点蚀，这种点蚀重复作用，使金刚石刀具产生严重磨损。由于实际应用中的精密零件，黑色金属及其合金材料占多数，一些传统的加工方法成本高，容易出现质量不稳定的现象，形状复杂的零件难以加工，为此，本文采用超声振动切削加工方法，对金刚石精细切削黑色金…     

SPDT超精密切削时切削变形与切削力的研究

研究了超精密切削时，单晶金刚石刀具与工件间的摩擦系数、刀具锋锐度、切削厚度等对切削变形系数、切削力及加工表面质量的影响。作者认为在超精密切削时，要提烹加工表面质量，优选金刚石刀具的晶面方向、提高金刚石刀具的锋锐度是十分重要的，在超精密切削单晶材料时，工件晶面的选择也是十分重要的。     

黑色金属的超精密镜面切削方法

黑色金属的超精密镜面切削是现代切削技术中的难题,本文对当前世界上这一技术领域内所进行的各种实验方法作了概略的叙述,指出了这些方法的特点,并预言实用阶段的黑色金属超精密镜面切削方法必将在不久问世。     

光学脆性材料的金刚石切削加工

重点对脆性材料的超精密研磨、抛光加工技术及超精密磨削加工技术和超精密切削加工技术进行了分析研究。分析表明,硬脆材料光学元件主要应进行超精密研磨、抛光及超精密磨削加工;软脆材料光学元件主要应进行金刚石切削加工。对软脆材料金刚石切削进行了试验设计,指出了光学脆性材料的金刚石切削加工过程不同于金属加工过程,通过控制切削条件可以实现脆性材料塑性域加工,提高光学脆性材料的表面加工质量。     

黑色金属的金刚石超声振动切削

黑色金属的金刚石超声振动切削大连理工大学（１１６２２４）张元良刘欣方加宝董桂英陈懋圻迄今为止,在生产中,天然金刚石只能用于切削有色金属、塑料及某些晶体材料,不能加工钢铁等黑色金属。这是因为在切削黑色金属时,金刚石刀具的磨损极快,使切削难以持续进行。在...     

超精密切削时刀具切削刃的作用机理分析

分析了金刚石刀具切削刃的切削作用、脆性材料超精密切削时切屑形成机理；对金刚石刀具切削刃钝圆半径、切削厚度、切削角三者之间的关系进行了描述。结果表明：脆性材料可以实现塑性域超精密切削加工；控制切削参数可以加工出满足要求的表面粗糙度和表面波纹度，为生产实际提供可靠的工艺条件及技术参数。     

金刚石刀具锋锐轮廓几何评定方法研究

金刚石刀具刃口的锋锐轮廓是影响超精密加工的一个重要参数。在对金刚石刀具刃口轮廓三维测量的基础上，提出了精密评定切削刃锋锐轮廓的几种新方法。其中对圆评定方法、椭圆评定方法和抛物线评定方法进行了研究，实验结果表明这些方法不仅具有较高的评定精度，而且还有利于对超精密微切削机理进行分析研究。     

高比重钨合金超声椭圆振动切削去除机理研究

高比重钨合金作为一种难加工金属材料,其应用范围一直受限于其超精密加工水平。超声椭圆振动切削技术在高比重钨合金超精密切削加工中极具应用前景,通过切削去除机理研究,可推动其在高比重钨合金超精密切削领域中的应用。因此,首先对超声椭圆振动切削轨迹进行分析,结合瞬时剪切角变化,建立了超声椭圆振动切削弯矩及切削力模型,并基于上述模型,通过与常规车削相对比,对超声椭圆振动切削特性进行分析。然后,采用单晶金刚石刀具,进行高比重钨合金超声椭圆振动划擦实验和切削实验,并通过SEM、白光共聚焦显微镜、X射线残余应力分析仪等设备对材料塑脆特性、切屑厚度、切削表面残余应力及切削表面加工损伤等进行检测与分析。理论分析与切削实验表明,与常规车削相比,超声椭圆振动切削下材料去除尺度由微米量级减小为纳米量级,高比重钨合金表现出更强的塑性;随着剪切角变化,超声椭圆振动切削在材料去除过程中,会产生更大的向下的分力,在切削表面留下更大的残余应力;超声椭圆振动切削下,切削方向与材料断裂方向更为一致,结合锋利的单晶金刚石刀具,有利于实现高比重钨合金超精密切削。     

超精密切削加工中几个主要问题的探讨

主要探讨了超精密切削加工机床以及金刚石刀具和超精加工条件的问题。     

金刚石刀具刀尖几何形状对超精密切削加工质量的影响

指出超精密切削实际上是刀具刀尖部分与工件的相互作用,分析了金刚石刀具刀尖几何形状和切削刃的锋利度对超精密切削加工质量的影响。认为正确地选择刀尖部分几何形状和修光刃钝圆半径是获得高质量加工表面的有力保证。     

Tool Wear in Ultra-Precision Diamond Cutting of Non-Ferrous Metals with a Round-Nose Tool

Tool wear causes the loss of the original profile accuracy of the cutting edge and degrades the form accuracy of machined surfaces. The purpose of this research is to clarify the tool-wear mechanism and its effect on machining accuracy in ultra-precision diamond cutting with a round-nose tool. Controlled cutting tests of Al 6061 were performed on a two-axis, ultra-precision turning machine. Single-crystal diamond tools were used in the experiment. The tool-wear pattern was studied based on the observation of the wear zone using a scanning electron microscope. The topographic characteristics of the chips were examined and the effect of the micro-cutting geometry on the tool wear was investigated theoretically and experimentally. The mutual effects of crystallographic dependence of wear resistance of diamonds and the change in the cutting velocity during machining are believed to be the main reasons causing uneven wear along the cutting edge. Measures for reducing the effect of tool wear are also discussed.     

Novel tool wear monitoring method in ultra-precision raster milling using cutting chips

Tool wear monitoring is a popular research topic in the field of ultra-precision machining. However, there appears to have been no research on the monitoring of tool wear in ultra-precision raster milling (UPRM) by using cutting chips. In the present research, monitoring tool wear was firstly conducted in UPRM by using cutting chips. During the cutting process, the fracture wear of the diamond tool is directly imprinted on the cutting chip surface as a group of ‘ridges’. Through inspection of the locations, cross-sectional shape of these ridges by a 3D scanning electron microscope, the virtual cutting edge of the diamond tool under fracture wear is built up. A mathematical model was established to predict the virtual cutting edge with two geometric elements: semi-circle and isosceles triangle used to approximate the cross-sectional shape of ridges. Since the theoretical prediction of cutting edge profile concurs with the inspected one, the proposed tool wear monitoring method is found to be effective.     

天然金刚石振动与气体保护切削黑色金属技术研究

对天然金刚石切削黑色金属的磨损机理进行了分析 ,提出了天然金刚石超声振动结合气体保护方法对黑色金属材料进行微量切削的新思路 ,并进行了不锈钢零件的切削实验。实验表明 ,当切削路程达到 2 0 0 0m时 ,工件表面粗糙度Ra小于 0 .15 μm ,后刀面磨损带宽小于 5 μm。     

超精密车削切屑形成过程的试验研究

超精密车削中的各种物理现象，如切削力、刀具磨损以及加工表面质量等问题，都是以切屑形成为基础的。而生产实践中出现的许多问题，如振动、卷屑和断屑等，又都与超精密切削过程密切相关。选用的材料种类和切削条件不同，可生成不同形态的切屑。文章提出了一种研究切屑形成过程新的试验方法，利用该方法能够得到金刚石车削时高清晰的金属材料塑性流动图像。     

硬脆及黑色金属材料的单点金刚石车削加工技术综述

单点金刚石车削技术是产生纳米特征表面的光学元件重要制造工艺之一。此加工技术在空间科学、生物医学工程、军事、国防和光学等领域有着广泛的应用。然而,金刚石刀具在切削硬脆和黑色金属材料时受到限制,如刀具磨损加剧、刀具寿命缩短以及工件表面加工质量降低等。为了减少刀具磨损和提高工件表面加工质量,相关学者提出了不同的解决方案,将从单点金刚石车削辅助工艺、工件改性、刀具性能改善和超硬材料及刀具方面梳理面向提高硬脆和黑色金属材料加工质量的单点金刚石车削加工技术相关研究,分析当前各种加工技术的优势与局限,提出未来将多种能场辅助的单点金刚石车削技术和基于聚焦离子束改性的金刚石刀具技术作为研究的重点。     

聚晶金刚石刀具振动切削不锈钢技术研究

使用聚晶金刚石刀具进行了超声波振动切削不锈钢的实验研究,研究了切削方式对切削力及已加工表面粗糙度的影响规律。通过对刀具磨损区微观形貌的观测,分析了PCD刀具切削不锈钢时的磨损机理。结果表明,化学磨损在金刚石刀具切削黑色金属时占主导地位。超声振动切削可明显减小切削变形、切削力及刀具磨损。     

Wear of monocrystalline diamond tools during ultraprecision machining of nonferrous metals

In studying the wear behavior of diamond cutting tools, a pragmatic appraoch has been chosen in which the tool wear and the change in cutting forces have been specifically determined as a function of tool life. Several nonferrous metals, such as copper, aluminium, and electroless nickel, have been machined. The influence of microstructural characteristics, crystallographic orientation, and mechanical surface state of diamonds on tool-wear behavior is investigated in considerable detail. It has been found that wear behavior of diamond tools depends strongly on workpiece material, so that when machining aluminium, all types of diamond show considerable and almost the same degree of wear. However, machining copper and electroless nickel entails much subtler wear characteristics; in fact, great differences in wear resistance between different types of diamonds were discerned. Type all diamonds in particular, both synthetic and natural, appear to be highly resistant to wear. The best crystallographic orientation for wear-resistant diamonds depends on the way the cutting tools are used.     

微结构自由曲面的超精密单点金刚石切削技术概述

回顾了超精密加工技术的发展,主要包括超精密加工设备的开发历程,以及超精密单点金刚石切削技术基础,并对微工程技术作一简要介绍;重点论述微结构自由曲面的微纳切削技术,包括单点金刚石车削(Single point diamond turning, SPDT),快刀伺服加工(Fast tool servo, FTS),金刚石微凿切(Diamond micro chiseling, DMC),光栅铣削等技术。指出微结构自由曲面测量领域面临的挑战和存在的问题,包括接触式测量和非接触式测量。通过几个典型微结构自由曲面的加工及测量的应用进行举例说明;最后介绍我国在超精密加工机床领域内的研制情况,展望了超精密切削技术未来发展趋势。     

Improvement of Local Surface Quality by Using Single Abrasive Abrasion Process

AFM-based wear process actually is single abrasive abrasion process. It is widely employed in the surface micro/nano machining for fabrication of structures at the nanometer scale exhibiting high removing ability of nanometer scale materials. In this study, application of AFM-based single abrasive abrasion process in the local surface quality (surface roughness) improvement was studied. Merged holes were fabricated using an AFM diamond tip with different wear parameters on the surface of germanium (Ge) machined by conventional ultra-precision diamond turning. Results showed that cracks left by diamond turning can be removed and the local surface quality can be improved. Also effects of the wear parameters on the surface roughness were investigated. The optimized parameters of the abrasion process for improving the surface quality were provided. It is verified that AFM-based single abrasive abrasion process is a novel approach to modify or repair local surface on the surface of parts manufactured by other methods.