CVD金刚石薄膜涂层刀具切削性能研究

本文采用不同涂层工艺的ＣＶＤ金刚石薄膜刀具切削高硅铝合金,观测比较刀具的磨损过程、磨损与破损形貌及工件表面粗糙度,分析ＣＶＤ金刚石薄膜刀具切削主崖裂口合金的磨损机理和失效原因。研究结果可为涂层工艺的提供了理论依据。     

金刚石薄膜涂层刀具及其切削性能的实验研究

用燃焰法进行了金刚石薄膜涂层刀具的沉积实验,研究了刀具基体材料对金刚石薄膜形成的影响,通过对ＳｉＣ颗粒增强铝复合材料的切削实验,研究了以金属Ｗ为基体的金刚石薄膜涂层刀具的切削性能。     

CVD金刚石涂层刀具切削性能与磨损机理研究

针对普通刀具切削质量差、刀具耐用度低等问题,对CVD涂层刀具制备方法及切削性能进行研究。首先以硬质合金刀具为基体通过CVD方法制备金刚石涂层,分析涂层表面形貌。然后在不同条件下进行铝合金材料的干式切削试验,分析金刚石涂层对切削力、切削温度以及工件表面粗糙度的影响规律。最后,通过对刀具磨损机理的分析,讨论涂层对刀具使用寿命的影响。研究结果表明,所制备的涂层刀具能够降低切削力和切削温度,大大提高刀具的切削性能和工件的表面质量,并能有效提高刀具使用寿命。     

金刚石涂层刀具铣削氧化锆义齿性能研究

氧化锆陶瓷义齿不论从材料的切削加工性,还是从义齿的结构特点上,对刀具的切削性能及寿命都有极高的要求。本文先对立铣刀加工预烧结氧化锆义齿的特点进行分析,得出义齿在加工中的失效主要是由切削冲击、过切和欠切引起的,然后通过刀具的寿命试验和磨损试验对金刚石涂层刀具和TiAlN涂层刀具进行了寿命、磨损的对比分析。在试验分析的过程中通过超景深显微镜对后刀面磨损带宽度和铣削距离进行记录,通过扫描电镜等仪器分析了两种不同涂层材料刀具加工后的前、后刀面磨损形貌和刀具的磨损机理。最终得出在磨钝标准:VB为0.1 mm的情况下,金刚石涂层刀具的寿命约是TiAlN涂层刀具的6.5倍,在切削过程中发生的主要磨损为磨粒磨损、化学磨损和冲蚀磨损。     

CVD金刚石涂层刀具高速铣削加工石墨模具研究进展

介绍了模具石墨的性能特点和切削加工机理,指出了复杂结构电火花石墨模具铣削加工中的困难,提出了CVD金刚石涂层刀具的解决方案。在此基础上介绍了国内外CVD金刚石涂层刀具在石墨模具高速铣削加工的工艺特点以及加工中CVD金刚石涂层刀具的磨损机制和破损失效形式,并列举了CVD金刚石涂层刀具在石墨模具高速铣削加工的应用,指出CVD金刚石涂层刀具高速铣削加工可解决石墨模具难以加工这一难题,若能进一步解决CVD金刚石涂层刀具的膜-基结合力和表面粗糙度问题,预期CVD金刚石涂层刀具高速铣削加工石墨模具可得以广泛推广应用。     

如何正确选择刀具涂层

对小型圆形刀具进行正确的表面处理可以提高刀具寿命，减少加工循环时间，提升加工表面质量。但是，根据加工需要正确选择刀具涂层有可能是一件令人困惑和费劲的工作。每一种涂层在切削加工中都既有优势又有缺点，如果选用了不恰当的涂层，有可能导致刀具寿命低于未涂层刀具，有时甚至会引出比涂层以前更多的问题。     

植晶工艺对金刚石涂层硬质合金刀具切削性能的影响

金刚石涂层刀具在高精与硬脆材料加工方面有着巨大的应用潜能。本文研究了纳米金刚石粉超声处理的植晶工艺对金刚石涂层/硬质合金刀具的影响因素。分别对比了传统两步法处理、纳米金刚石粉超声处理、优化超声处理三种预处理效果。采用热丝CVD设备生长CVD金刚石涂层,扫描电子显微镜(SEM)、和拉曼光谱仪(Ramanspectrum)分别用于表征沉积金刚石涂层前后的基底表面形貌及其涂层质量。最后,利用铣削测试研究了所制备的涂层刀具的切削性能。结果表明,三种预处理后的硬质合金表面金刚石取向以及质量相似。经纳米金刚石粉超声后的硬质合金刀具表面生长了很多金刚石"生长瘤",再经酒精超声处理,可消除涂层前刀片表面团簇体,避免瘤的产生,其刀具加工效果得到了较大的提高。     

Advanced coated ceramic tools for machining superalloys

The main limitation on the use of nickel-base superalloys, such as INCONEL 718, is the difficulty in conventional-type machining. The use of high cutting speed to achieve both machining adiabatic conditions and high productivity is necessary for their applications. This non-conventional type machining results in a short life-span of tools, even for those expensive ceramic ones with reinforced SiC whiskers (SiC_w) suitable for use at high cutting speeds. The aim of the paper is to present the results of a new idea proposed by the authors to obtain an increase in tool life at high cutting speed by minimizing the temperature effects on composite reinforcement mechanisms. The 2090 SiC whiskers reinforced A1₂O₃ tools were CrN and (Ti,AI)N coated using the PVD technique, and comparative machining tests on INCONEL 718 were carried out using uncoated and coated tools. After machining, the tools were observed with a scanning electron microscope (SEM), and EDAX (X-ray) semiquantitative analyses were performed. The behaviour of the CrN and (Ti,AI)N layers using various cutting conditions was analysed and different wear mechanisms along the tool chip contact length were observed. The cause and the mechanisms of wear were deduced and mathematic models linking tool life with process parameters were suggested.     

加工氧化锆陶瓷的金刚石涂层刀具的制备及切削试验研究

使用热丝化学气相沉积法(HFCVD)在硬质合金片以及球头铣刀表面沉积了微米金刚石薄膜(MCD),纳米金刚石薄膜(NCD)以及微米纳米复合金刚石薄膜(MNCD),通过扫描电子显微镜和拉曼光谱对其进行表征,结果呈现出典型的金刚石薄膜的性质,沉积质量高。金刚石薄膜与氧化锆陶瓷的摩擦磨损实验表明:金刚石薄膜能有效地降低对磨时的摩擦系数以及磨损率。使用三种金刚石薄膜涂层铣刀对氧化锆陶瓷进行铣削加工试验,结果显示:金刚石涂层刀具磨损率大幅度降低,刀具寿命显著增强。     

Nanocrystalline diamond coating tools for machining high-strength Al alloys

Diamond coating tools have been increasingly used for machining advanced materials. Recently, a microwave plasma-assisted chemical vapor deposition (CVD) technology was developed to produce diamond coatings which consist of nano-diamond crystals embedded into a hard amorphous diamond-like carbon matrix. In this study, the nanocrystalline diamond (NCD) coating tools were evaluated in machining high-strength aluminum (Al) alloy. The conventional CVD microcrystalline diamond coating (MCD) tools and PCD tools were also tested for performance comparisons. In addition, stress distributions in diamond coating tools, after deposition and during machining, were analyzed using a 2D finite element (FE) thermomechanical model.

The results show that catastrophic failures, reached in all except one machining conditions, limit the NCD tool life, which is primarily affected by the cutting speed. In addition, coating delamination in the worn NCD tools is clearly evident from scanning electron microscopy (SEM) and force monitoring in machining can capture the delamination incident. At a high feed, coating delamination may extend to the rake face. Furthermore, SEM observations of coating failure boundaries show intimate coating-substrate contact. Though the NCD tools are inferior to the PCD tools, they substantially outperform the MCD tools, which failed by premature delamination. The diamond coating tools can have high residual stresses from the deposition and stresses at the cutting edge are highly augmented. Further machining loading causes the stress reversal pattern which seems to correlate with the tool wear severity.     

Contour finish turning operations with coated grooved tools: Optimization of machining performance

This paper presents a new methodology for optimization of machining performance in contour finish turning operations. Two machining performance measures, chip breakability and surface roughness, are considered as optimization criteria due to their importance in finishing operations. Chip breakability covers two major factors: chip shape and size. Comprehensive case studies are presented to demonstrate the determination and application of optimal cutting conditions through experimental validation.     

Cutting performance of diamond tools during ultra-precision turning of electroless-nickel plated die materials

This study is an attempt (a) to observe the wear characteristic of diamond tool with 200 km cutting distance and to study the effects of wear on the surface roughness and cutting forces and (b) to optimize various cutting parameters such as depth of cut, feed rate, spindle speed and phosphorus content. The experimental results showed that tool wear was not so significant although some defects on rake face were observed after cutting 15.6 km. Further cutting showed that the surface roughness increases with cutting distance, and that the cutting forces were larger than thrust force at the beginning of cutting, but after cutting 130 km, thrust force became larger and increased rapidly. It was also observed that forces increase with the increase of depth of cut, spindle speed and feed rate, and decrease with the increase of phosphorus content of the plating. Depth of cut has no significant effect on surface roughness, while it increases with increase of feed rate and decreases with the increase of percentage of phosphorus content in the workpieces. In case of spindle speed, surface roughness decreases with the increase of spindle speed up to a certain value and then starts to increase with the increase of spindle speed.     

氧化镍镀覆金刚石对固结磨料研磨垫加工性能影响

黏结剂把持磨粒的能力对固结磨料研磨垫的加工性能有重要影响。选择K9玻璃作为加工对象、不饱和树脂作为黏结剂,通过沉积法在金刚石表面镀覆一层氧化镍改善金刚石与树脂的结合性能,研究了镀覆后金刚石的形貌和热处理工艺,及其对固结磨料研磨垫加工性能的影响。研究表明:镀覆量达到30%,氧化镍镀覆金刚石的热处理工艺为3 h/450℃+5 h/500℃时,能够提高固结磨料研磨垫25%的材料去除速率。     

Cutting with coated tools: Coating technologies,characterization methods and performance optimization

Coated tools constitute the majority of the tools applied in material removal processes, rendering the employment of uncoated ones as an exception. A broad growing market of coated cutting tools has been developed. Moreover, numerous material- and manufacturing-engineers have joint their expertise, aiming at developing coatings meeting the needs for processing the most difficult-to-cut materials at the most extreme cutting conditions. The emerging of new workpiece, tool and film materials, the evolution of sophisticated coatings’ characterization methods and the continuous need for higher productivity rates, maintain vivid the industrial and scientific interest for further advancing this field.     

Cutting force model for machining of CFRP laminatewith diamond abrasive cutter

The article presents a cutting force model for trimming operations of CFRP laminate with diamond abrasive cutters. Those tools are more and more encountered on industrial applications of CFRP trimming, due to their abrasion resistance and their low cost. Contrary to endmills, they consist of a large number of cutting grits, randomly distributed around the tool. To tackle the issue, a continuous model of tool engagement is proposed. Validity of the approach is verified. A mechanical model of cutting forces, adapted to CFRP laminate, is then presented. The evolution of specific cutting coefficient in relation to fibres orientation is investigated through a piecewise constant model. It leads to the proposal of a sine model for the specific cutting coefficients. The simulated forces are in good agreement with the experimental results of cutting tests, carried out in multidirectional CFRP laminate for different fibres orientation and widths of cut. Cutting mechanisms are finally discussed depending on fibres orientation.     

Wear mechanisms of PVD ZrN coated tools in machining

Medium-frequency magnetron sputtered PVD ZrN coatings (ZrN, ZrN/Zr) were deposited on YT15 (WC + 15%TiC + 6%Co) cemented carbide. Microstructural and fundamental properties of these ZrN coatings were examined. Dry machining tests on hardened steel were carried out with these coated tools. The wear surface features were examined by scanning electron microscopy. Results showed that deposition of the PVD ZrN coatings onto the YT15 cemented carbide causes great increase in surface hardness. The ZC-1 coated tool (ZrN/YT15 without interlayer) has the highest surface hardness; while the ZC-2 (ZrN/Zr/YT15 with a Zr interlayer) shows the highest adhesion load for the coatings to the substrate. The ZrN coated tools exhibit improved rake and flank wear resistance to that of the YT15 tool. The coated tools with a Zr interlayer (ZC-2) have higher wear resistance over the one without Zr interlayer (ZC-1). The rake wear of the ZrN coated tools at low cutting speed was mainly abrasive wear; while the mechanism responsible for the rake wear at high cutting speed was determined to be adhesion. Extensive abrasive wear accompanied by small adhesive wear were found to be the predominant flank wear mechanisms for the ZrN coated tools.