正交车铣高强度钢的刀具耐用度及磨损机理研究

通过TiN涂层硬质合金端铣刀正交车铣58SiMn高强度钢的刀具磨损试验,建立了刀具耐用度T-(vc,fa,fz)关系泰勒公式,分析了各切削用量对刀具耐用度的影响关系;对正交车铣刀具的磨损研究表明刀具表面材料的疲劳—剥落和切削刃微崩以及在高温下刀具材料中的元素与周围介质发生的化学反应磨损等是造成刀具磨损的主要原因。     

Machining of sintered steel under different lubrication conditions

Cutting experiments of sintered steel Fe–2Cu–0.8C under different lubrication/cooling conditions and with different tool materials were performed in order to clarify the reasons for the low machinability of the sintered steel, and investigate the applicability of minimum quantity of lubricant (MQL) to the machining of sintered steel. As a theoretical approach to the short tool life in machining sintered steel, the impacts to the cutting edge caused by micro-voids were theoretically modeled, and it was revealed that the cutting edge suffered from impacts at a very short interval causing high cycle fatigue. Extremely short tool life in dry machining of sintered steel already used for wet machining proved that coolant definitely increased the stress amplitude in high cycle fatigue. Application of the air jet to a tool showed the positive effect in reducing tool wear. This indicated the possibility that micro-cracks nucleated by high cycle fatigue were healed by oxidation. MQL cutting with small amount of oil and air jet is proved to be acceptable for machining sintered steel from the results of cutting experiments using uncoated and coated carbide and cermet tools. Finally, it is confirmed that thick coating of a carbide tool is effective for dramatically improving the machinability.     

Tool wear and tool life in end milling of 15–5 PH stainless steel under different cooling and lubrication conditions

Most of the machining operations on stainless steel alloys are carried out with cutting fluid due to the poor machinability of this kind of material. Tool wear mechanisms are directly influenced by the cooling and lubrication condition to which the tool is exposed, especially in interrupted cutting processes. This work investigates tool wear mechanisms for an end milling operation of a precipitation-hardened martensitic stainless steel under four different cooling and lubrication conditions. The results demonstrated that the cooling and lubrication condition strongly influences tool life and the tool wear mechanism, and furthermore, that tool lubrication rather than cooling should be the purpose for using cutting fluid in this kind of operation, in order to avoid damage caused by tool temperature variations.     

CN35硬质合金涂层刀具高速车削淬硬钢的磨损与破损形态

借助于扫描电镜照片和能谱分析,对高速车削淬硬45钢时CN35硬质合金涂层刀具的失效形态及其机理进行了观察和分析。结果显示,在高速切削条件下,涂层刀具的失效形态主要分为破损与磨损两种,刀具正常磨损失效过程仍然遵循常规切削条件下三个阶段的程序。刀具破损失效发生在低速切削阶段,且随着切削速度的提高,破损部位由后刀面转移到前刀面;高速切削时,刀具失效形式倾向于后刀面磨损、边界磨损和切削刃斜面磨损,因高热、粘结、疲劳、氧化、扩散和热裂等原因造成刀具切削功能丧失。     

涂层刀具磨损对工件表面质量的非线性影响关系

在高速硬态切削过程中,涂层刀具高速切削失效形态分为非正常磨损（破损）与正常磨损两种。刀具非正常磨损失效发生在低速切削时,而高速切削过程中的刀具失效形式倾向于后刀面磨损、边界磨损和切削刃斜面磨损等多种一常磨损彤式的组合。本文通过涂层刀具高速车削45#钢的试验,研究了刀具磨损对工件表面质量的影响。试验表明：提高切削速度,工件已加工表面质量并未随刀具磨损情况加剧而呈线性下降,刀具磨损对已加工表面质量负面影响作用的减轻,使表面质量在一定程度上得到了改善。     

AN EXPERIMENTAL EVALUATION OF CUTTING TEMPERATURES DURING HIGH SPEED MACHINING OF HARDENED D2 TOOL STEEL

This paper investigates experimentally the effects of different process parameters on the cutting edge temperature during high speed machining of D2 tool steel using polycrystalline cubic boron nitride (PCBN) tools. The cutting edge temperature is measured using thermocouples. The process parameters considered are cutting speed, feed rate, nose radius, rake angle, and tool wear. The effects of different edge preparations including sharp, honed and chamfered are also investigated. The results show that increasing cutting speed and feed rate increases the cutting temperature while increasing nose radius reduces the cutting edge temperature. In addition, there is an optimum rake angle value at which minimum cutting temperature is generated.     

气体风冷高速铣削的刀具磨损研究

立铣刀高速铣削方式加工可显著提高淬硬钢模具的加工效率,但同时也存在切削温度高、刀具磨损快的问题.对刀具与工件的切削接触区域进行充分冷却及润滑是解决此问题的有效方法.对气体风冷高速切削展开刀具磨损研究,涉及两种气体冷却方法—压缩气体冷却法以及涡流管冷却法.实验结果表明,涡流管冷却法相比压缩气体冷却法可降低切削区域温度,有...     

硬质合金刀具高速车铣和铣削TC4钛合金磨损试验对比

采用H13A未涂层硬质合金刀具对TC4钛合金进行高速正交车铣和铣削试验,并从刀具磨损破损形态、磨损机理及其寿命等方面进行对比分析。研究表明:高速正交车铣和铣削钛合金时,前、后刀面主要以粘结磨损为主,车铣加工时在切削刃口易形成积屑瘤及连续切屑,但对刀具材料粘结较轻;高速铣削时,对刀具材料粘接较重,在前刀面刃口附近形成凹坑及崩刃;后刀面最大磨损的位置不相同。试验对比了相同切削条件时刀具使用寿命,结果表明采用正交车铣加工可以获得更长的刀具使用寿命。     

Tool crater wear depth modeling in CBN hard turning

Hard turning has been receiving increased attention because it offers many possible benefits over grinding in machining hardened steel. The wear of cubic boron nitride (CBN) tools, which are commonly used in hard turning, is an important issue that needs to be better understood. For hard turning to be a viable replacement technology, the high cost of CBN cutting tools and the cost of down-time for tool changing must be minimized. In addition to progressive flank wear, microchipping and tool breakage (which lead to early tool failure) are prone to occur under aggressive machining conditions due to significant crater wear and weakening of the cutting edge. The objective of this study is to model the CBN tool crater wear depth (K_T) to guide the design of CBN tool geometry and to optimize cutting parameters in finish hard turning. First, the main wear mechanisms (abrasion, adhesion, and diffusion) in hard turning are discussed and the associated wear volume loss models are developed as functions of cutting temperature, stress, and other process information. Then, the crater wear depth is predicted in terms of tool/work material properties and process information. Finally, the proposed model is experimentally validated in finish turning of hardened 52100 bearing steel using a low CBN content tool. The comparison between model predictions and experimental results shows reasonable agreement, and the results suggest that adhesion is the dominant wear mechanism within the range of conditions that were investigated.     

不同涂层刀具切削淬硬H13钢加工性能研究

为了研究不同涂层刀具切削淬硬H13钢的切削性能,进行了多层Ti化合物涂层、TiAlN涂层以及MTTiCN厚Al_2O_3TiN涂层材料刀具车削加工淬硬H13钢试验,分析了不同的涂层材料刀具与切削力、切削温度、涂层刀具磨损以及刀具寿命的关系。研究得出:多层Ti化合物涂层刀具受到三个方向的力都大于其它两种涂层的刀具,而且切削温度最高;用TiAlN涂层刀具切削时温度最低;切削过程中三种刀具后刀面磨损程度不同,发现多层Ti化合物涂层刀具磨损最为严重,寿命最短;MT-TiCN厚Al_2O_3Ti N涂层材料刀具比多层Ti化合物涂层刀具寿命长30%;TiAlN涂层刀具的切削寿命最长比多层Ti化合物涂层刀具寿命长45%。     

TiN涂层刀具切削高锰钢的磨损破损研究

研究奥氏体高锰钢切削过程中TiN涂层硬质合金刀具的磨损、破损机制,测量了切削温度并得出后刀面磨损量与 切削时间和切削速度的关系曲线,以及刀具前、后刀面显微磨损、破损形貌和化学变化。结果表明,TiN涂层硬质合金刀 具切削奥氏体高锰钢时耐磨性优于单一硬质合金刀具,且适于低速切削(小于30m/min)。     

Wear behaviour of alumina based ceramic cutting tools on machining steels

The advanced ceramic cutting tools have very good wear resistance, high refractoriness, good mechanical strength and hot hardness. Alumina based ceramic cutting tools have very high abrasion resistance and hot hardness. Chemically they are more stable than high-speed steels and carbides, thus having less tendency to adhere to metals during machining and less tendency to form built-up edge. This results in good surface finish and dimensional accuracy in machining steels. In this paper wear behaviour of alumina based ceramic cutting tools is investigated. The machining tests were conducted using SiC whisker reinforced alumina ceramic cutting tool and Ti[C,N] mixed alumina ceramic cutting tool on martensitic stainless steel-grade 410 and EN 24 steel work pieces. Flank wear in Ti[C,N] mixed alumina ceramic cutting tool is lower than that of the SiC whisker reinforced alumina cutting tool. SiC whisker reinforced alumina cutting tool exhibits poor crater wear resistance while machining. Notch wear in SiC whisker reinforced alumina cutting tool is lower than that of the Ti[C,N] mixed alumina ceramic cutting tool. The flank wear, crater wear and notch wear are higher on machining martensitic stainless steel than on machining hardened steel. In summary Ti[C,N] mixed alumina cutting tool performs better than SiC whisker reinforced alumina cutting tool on machining martensitic stainless steel.     

The effects of cutting parameters on tool life and wear mechanisms of CBN tool in high-speed face milling of hardened steel

High-speed face milling of AISI H13 hardened steel is conducted in order to investigate the effects of cutting parameters on tool life and wear mechanisms of the cubic boron nitride (CBN) tools. Cutting speeds ranging from 400 to 1,600 m/min are selected. For each cutting speed, the metal removal rate and axial depth of cut are fixed, and different combinations of radial depth of cut and feed per tooth are adopted. The tool life, tool wear progression, and tool wear mechanisms are analyzed for different combinations of cutting parameters. It is found that for most of the selected cutting speeds, the tool life increases with radial depth cut and then decreases. For each cutting speed, the CBN tool life can be enhanced by means of adopting suitable combination of cutting parameters. When the cutting speed increases, the normal wear stage becomes shorter and the tool wear rate grows larger. Because of the variations of cutting force and tool temperature, the tool wear mechanisms change with different combinations of cutting parameters even at the same cutting speed. At relatively low cutting speed, in order to acquire high tool life of the CBN tool, the tool material should possess sufficient capability of resisting adhesion from the workpiece. When relatively high cutting speed is adopted, retention of mechanical properties to high cutting temperature and resistance to mechanical impact are crucial for the enhancement of the CBN tool life.     

铝合金薄壁中空结构件重负荷铣削刀具寿命及刀具磨损研究

使用高速钢和硬质合金刀具,在机床转速n=2000-5000r/min、进给速度vf=1000mm/min、轴向切深ap=20mm、径向切宽aw=10-20mm的切削用量范围内对铝合金薄壁中空结构件重负荷铣削加工刀具寿命及刀具磨损进行研究。结果表明:M42高速钢刀具由于刀具磨损率高、刀具破损和粘结严重而不适合该结构件的重负荷铣削;非波刃粉末冶金高速钢和硬质合金刀具具有良好的适应性,但无刀尖圆弧半径的高速钢刀具易发生刀尖破损,涂层硬质合金刀具易发生涂层过早剥落;波刃粉末冶金高速钢刀具易于发生刀具严重粘结,只宜在较低的机床转速下进行重负荷铣削加工;机床转速和径向切宽对刀具寿命有显著影响。     

PCBN刀具断续切削磨损机理的研究

研究了BN250断续车削淬火钢SAE8822十字轴的磨损现象。试验结果显示微崩刃是断续车削中导致刀具失效的主要因素,工件与BN250刀具元素之间的化学反应和扩散作用削弱了结合剂与CBN基体直接的结合强度,是导致刀具破损发生的主要因素。     

纳米切削工艺中刀具原子尺度磨损机理的分子动力学分析

为研究刀具磨损的微观机理,以单晶铝为例,采用分子动力学方法对纳米切削中刀具失效的原子级物理本质进行研究。模拟结果显示,随着切削深度的增加,能够形成化学键的配对原子数也急剧增加,导致刀具的扩散磨损加剧;晶体的各向异性对刀具扩散磨损影响很小,说明扩散磨损主要是一种化学过程;扩散磨损生成的积屑瘤代替刀具进行切削,使得超精密加工的表面质量恶化,切削区域温度上升,进一步加剧扩散磨损过程。     

氧化锆生物陶瓷铣削的刀具磨损

为了研究完全烧结氧化锆陶瓷铣削过程中金刚石刀具的磨损及其对切削过程的影响,进行了氧化锆铣削实验。分析了刀具磨损带的扩展过程以及切削力随刀具磨损过程的变化规律。通过观测切削表面微观形貌随刀具磨损过程的演变,对刀具磨损与切削模式之间的关系进行了探讨,最后揭示了刀具磨损机理。研究结果表明：铣削氧化锆陶瓷时刀具磨损随切削过程从刃口扩展到后刀面,同时切削模式从延脆混合去除转变为完全脆性去除,刀具磨损模式是崩刃、剥落及石墨化磨损。     

Investigation of dry machining with embedded heat pipe cooling by finite element analysis and experiments

This paper investigates the performance of a cutting tool embedded with a heat pipe on reducing cutting temperature and wear in machining. The temperature of a tool plays an important role in thermal distortion and the machined part’s dimensional accuracy, as well as the tool life in machining. A new embedded heat pipe technology has been developed to effectively remove the heat generated at the tool–chip interface in machining, thereby, reducing tool wear and prolonging tool life. In particular, the technique can effectively minimize pollution and contamination of the environment caused by cutting fluids, and the health problems of skin exposure and particulate inhalation in manufacturing. The ANSYS finite element analysis simulations show that the temperature near the cutting edge drops significantly with an embedded heat pipe during machining. Temperature measurements at several locations on the cutting tool insert agree with the simulation results both with and without the heat pipe. Experiments were carried out to characterize the temperature distributions when performing turning experiments using a cutting tool installed with an embedded heat pipe. The performance of the heat pipe on reducing the cutting tool temperature was further supported by the observations of cutting tool material color, chip color, and the chip radius of curvature.     

新型陶瓷刀具材料的耐磨损性能

研究了近几年来所研制成功的几种新型陶瓷刀具材料切削加上高强钢、高温镍基合金、淬硬钢与铸铁时的耐磨性能。结果表明:加工不同材料时刀具的耐磨损能力不同,在实际应用时可根据需要选用合适的刀具材料。