高速切削淬硬模具钢刀具磨损的对比实验研究

使用PCBN和陶瓷两种材质的刀具对淬硬模具钢Cr12MoV进行高速切削试验,深入研究了高速切削时的刀具寿命、刀具磨损形态和磨损原因,得出如下结论:相同的切削条件下,PCBN刀具寿命约为陶瓷刀具的2～3倍,当切削速度由153 m/min增大到241 m/min时,两种材质刀具寿命均下降50％以上;在相对低速下切削时,PCBN刀具和陶瓷刀具磨损形态主要为月牙洼和后刀面磨损,在相对高速下切削时,两种刀具均出现破损,破损形态主要包括崩刃和片状剥落等;PCBN刀具磨损原因主要为黏结磨损、氧化磨损和扩散磨损,陶瓷刀具的主要磨损原因有磨粒磨损、黏结磨损和扩散磨损;相同切削条件下,PCBN刀具抗磨粒磨损的能力好于陶瓷刀具,而陶瓷刀具的抗氧化性能要好于PCBN刀具;切削速度对刀具磨损原因有重要影响,随着切削速度的增大,磨粒磨损程度和黏结磨损程度均减弱.     

铝合金切削过程刀具磨损预测研究

为更精确地研究刀具磨损,建立刀具磨损模型至关重要。目前刀具磨损的模型主要是经典的刀具磨损模型和刀具磨损预测模型,刀具磨损预测模型主要为人工神经网络、隐马尔可夫模型和支持向量机模型。分析铝合金切削过程中的刀具磨损机制,总结经典的刀具磨损模型,梳理刀具磨损预测模型。铝合金切削过程中刀具主要的磨损机制为黏着磨损、扩散磨损和磨粒磨损。结果表明：在黏着磨损和磨粒磨损的基础上考虑扩散磨损的刀具磨损理论模型最接近实际加工。     

复合织构刀具切削铝合金的性能∗

基于铝合金材料切削的现状和需求,针对单一织构刀具存在的抗黏减摩性能不足的问题,将不同织构应用于刀-屑接触区域,提出刀具前刀面分区异构的思想。利用皮秒激光在刀具黏结区与滑移区分别加工凹坑和沟槽,并调整沟槽的取向(平行 / 垂直于主切削刃),得到上下型(SXDV 和 SXDP)和左右型(ZYDV 和 ZYDP)四种复合织构刀具。对 6061 铝合金进行湿切削试验,研究不同区域内添加不同织构对刀-屑接触表面摩擦状态的影响。研究结果表明,对比无织构和单一织构刀具, ZYDP 复合织构刀具展现了更好的切削性能。具体表现如下：与无织构刀具相比,ZYDP 刀具的主切削力降低 30.7%,刀面黏结面积减少 63.9%,切屑卷曲半径减少 27.4%。合理的复合织构方案可以明显改善刀具切削过程中的黏结磨损问题,延长了刀具寿命。复合织构方案的提出以及相应的激光加工过程可为织构刀具的设计及实际应用提供新思路。     

基于Archard磨损模型的超细晶陶瓷刀具切削淬硬钢的寿命预测

为了预测超细晶陶瓷刀具的寿命,在建立Archard磨损模型和切削有限元模型、摩擦模型的基础上,进行了宏观尺度的模拟仿真和试验。主切削力、刀屑间压力随进给量增大而增大,刀屑之间温度、滑动速度随进给量增大先增大再降低。切削深度对刀屑之间的滑动速度和压力影响较小,但对刀/屑间的温度和主切削力影响较大。根据宏观尺度的超细晶陶瓷切削过程数值模拟的数据结果分析和统计、多元线性拟合、泰勒寿命公式得到超细晶陶瓷刀具的寿命预测模型,进行了超细晶陶瓷刀具切削实验验证,该模型的建立为超细晶陶瓷刀具的实际应用打下理论基础。     

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。     

硬质合金刀具正交车铣TC4钛合金磨损形貌及机制分析

在车铣复合加工中心Mazak Integrex 200Y上,切削速度为v=150、200 m/min及干式切削条件下,采用硬质合金刀具H13A对钛合金TC4进行正交车铣(顺铣)磨损试验。研究表明高速正交车铣钛合金时,正常磨损阶段前刀面出现不同程度切屑黏结及积屑瘤,后刀面主要以黏结磨损为主,磨损相对均匀;急剧磨损阶段,前刀面切屑黏结加剧,形成连续切屑,缠绕刀具;后刀面由于黏结作用刀具材料被切屑黏结物带走,形成黏结凹坑。刀具磨损的主要原因为黏结磨损、氧化磨损,通过X射线电子能谱(XPS)证明刀具磨损表面有TiO_2、WO_3和Co_3O_4等氧化物生成,分析其对刀具磨损的影响。     

硬质合金刀具高速干铣削Ti6Al4V刀具寿命研究及切削参数优化

Ti6Al4V是典型的难加工材料,切削效率低,刀具磨损严重。文章对硬质合金刀具在高速范围内干铣削Ti6Al4V进行了正交试验,获得了干切削状态下铣削刀具寿命的经验公式,并利用扫描电镜（SEM）和能谱分析（EDS）研究了铣削刀具的磨损形态和磨损机理,粘结、扩散及氧化是硬质合金刀具的主要磨损机理。最后,利用等寿命-效率响应曲面法,对硬质合金刀具在干切削状态下铣削Ti6Al4V的切削参数进行了优化,在效率不变的情况下,适当降低切削速度,增大切削深度,可以提高刀具寿命。试验刀具的切削参数优化结果为：切削速度40—60m／min、轴向切削深度0．5—1mm、径向切深7—10mm、进给量0．07—0．1mm／r,在建议切削参数下刀具寿命约在30—50min。     

高速切削摩擦学研究

高速切削过程中的摩擦直接影响刀具失效(磨损和破损),刀具使用寿命、工件的加工精度以及已加工表面质量。文章综述了高速切削摩擦学研究进展,重点介绍了高速切削中刀-屑之间和刀-工之间的摩擦学特性,阐述了刀具前刀面与后刀面的磨损形态和磨损机理,以及高切削过程中的冷却/润滑条件和不同的切削环境对刀具和工件的影响。展望了高速切削摩擦学的发展方向。     

高速切削硬态AISIH13的PCBN刀具磨损机制研究

采用超硬刀具精加工模具工作零件的“以切代磨”机加工艺能够显著提高模具使用寿命。但目前对此研究还甚少。以超硬刀具PCBN高速切削硬态AISIH13（HRC53），并用测温仪、光学仪、工具显微镜(XGJ-1)及JSM 5600LV型扫描电镜等对刀具磨损进行观察、检测与分析。结果表明：前后刀面主要以黏结磨损为主，但前刀面磨损主因是切削热，而后刀面磨损主因是机械应力，且在主切削刃上常发生沟槽磨损，若不平衡切削时亦会产生不规则破损。     

纳米氧化锆增韧氧化铝基陶瓷刀具切削性能的研究（Ⅱ）

研究新型陶瓷刀具A15Zc和A20Z(c+m)切削淬硬40Cr合金钢时的切削性能,并与已经商业化的陶瓷刀具SG4的切削性能进行了对比。结果表明:刀具后刀面磨损量随切削深度的增加而增大,而切削速度对刀具后刀面磨损量的影响较小;在较小的切削深度下切削时刀具具有良好的切削性能,A15Zc和A20Z(c+m)的抗磨损能力都好于SG4刀具;刀具的主要磨损形态为前后刀面磨损,主要磨损机制为前刀面的黏结磨损和后刀面的磨粒磨损。     

Wear behavior of Al2O3/Ti(C,N)/SiC new ceramic tool material when machining tool steel and cast iron

Design, fabrication and application of ceramic cutting tools are one of the important research topics in the field of metal cutting and advanced ceramic materials. In the present study, wear resistance of an advanced Al₂O₃/Ti(C,N)/SiC multiphase composite ceramic tool material have been studied when dry machining hardened tool steel and cast iron under different cutting conditions. Microstructures of the worn materials were observed with scanning electronic microscope to help analyze wear mechanisms. It is shown that when machining hardened tool steel at low speed wear mode of the kind of ceramic tool material is mainly flank wear with slight crater wear. The adhesion between tool and work piece is relatively weak. With the increase of cutting speed, cutting temperature increases consequently. As a result, the adhesion is intensified both in the crater area and flank face. The ceramic tool material has good wear resistance when machining grey cast iron with uniform flank wear. Wear mechanism is mainly abrasive wear at low cutting speed, while adhesion is intensified in the wear area at high cutting speed. Wear modes are dominantly rake face wear and flank wear in this case.     

Cutting Performance and Wear Behavior of AlTiN-and TiAlSiN-Coated Carbide Tools During Dry Milling of Ti-6Al-4V

Machining, especially dry machining of titanium alloys, has been one of the most significant challenges for carbide cutting tools. In this study, aluminum-rich AlTiN coating, as well as TiAlSiN nanocomposite coating, were successfully employed for dry milling of Ti-6Al-4V alloy with high efficiency and long tool life. At the cutting speeds of 150 m/min and 200 m/min, the tool life of the TiAlSiN-coated tool exceeds that of AlTiN-coated tool by 32 and 66%, respectively. The wear modes for both coated tools include the uniform flank wear, smooth wear, chipping, coating and substrate flaking, crater and notch wear, and the wear mechanisms include adhesion, diffusion, oxidation and crack. Among them, the wear mechanism is dominated by the adhesion and oxidation wear. As compared with AlTiN coating, TiAlSiN coating exhibits better mechanical properties and oxidation resistance, which contribute to a better cutting performance, fewer thermal cracks and smaller and uniform workpiece chips during the dry milling of Ti-6Al-4V alloy.     

Tool life and wear mechanisms in high speed machining of Ti–6Al–4V alloy with PCD tools under various coolant pressures

Usage of titanium alloys has increased since the past 50 years despite difficulties encountered during machining. Many studies involving different tool materials, cutting parameters, tool geometry and cutting fluids when machining this important aerospace material have been published. However, there are relatively few literatures available on the application of ultra hard tools in the machining of titanium-alloys. The primary objective of this study is to investigate the behaviour of Polycrystalline Diamond (PCD) tools when machining Ti–6Al–4V alloy at high speed conditions using high pressure coolant supplies. Tool performance under different tribological conditions and the dominant wear mechanisms were investigated. Increase in coolant pressure tends to improve tool life and reduce the adhesion tendency, accelerated by the susceptibility of titanium alloy to gall during machining. Adhesion and attrition are the dominant wear mechanisms when machining at the cutting conditions investigated.     

High-speed milling of titanium alloys using binderless CBN tools

The performance of conventional tools is poor when used to machine titanium alloys. In this paper, a new tool material, which is binderless cubic boron nitride (BCBN), is used for high-speed milling of a widely used titanium alloy Ti–6Al–4V. The performance and the wear mechanism of the BCBN tool have been investigated when slot milling the titanium alloy in terms of cutting forces, tool life and wear mechanism. This type of tool manifests longer tool life at high cutting speeds. Observations based on the SEM and EDX suggest that adhesion of workpiece and attrition are the main wear mechanisms of the BCBN tool when used in high-speed milling of Ti–6Al–4V.     

On temperatures and tool wear in machining hypereutectic Al–Si alloys with vortex-tube cooling

This study investigates dry machining of hypereutectic silicon–aluminum alloys assisted with vortex-tube (VT) cooling. The objective is to reduce cutting temperatures and tool wear by enhanced heat dissipation through the chilled air generated by a VT. A machining experiment, cutting mechanics analysis, and temperature simulations are employed to (1) model the heat transfer of a cutting tool system with VT cooling applied, (2) explore effects of cooling setting and machining parameters on the cooling efficiency, and (3) evaluate VT cooling effects on tool wear. A390 alloy is machined by tungsten carbides with cutting forces and geometry measured for heat source characterizations as the input of temperature modeling and simulations. VT cooling is approximated as an impinging air jet to estimate the heat convection coefficient that is incorporated into the heat transfer models. The major findings include: (1) VT cooling may reduce tool wear in A390 machining depending upon machining conditions, and the outlet temperature is more critical than the flow rate, (2) cooling effects on temperature reductions, up to 20 °C, decrease with the increase of the cutting speed and feed, and (3) tool temperature decreasing by VT cooling shows no direct correlations with tool wear reductions.     

Failure mechanisms of TiB2 particle and SiC whisker reinforced Al2O3 ceramic cutting tools when machining nickel-based alloys

In this paper, Al₂O₃/TiB₂/SiC_w ceramic cutting tools with different volume fraction of TiB₂ particles and SiC whiskers were produced by hot pressing. The fundamental properties of these composite tool materials were examined. Machining tests with these ceramic tools were carried out on the Inconel718 nickel-based alloys. The tool wear rates and the cutting temperature were measured. The failure mechanisms of these ceramic tools were investigated and correlated to their mechanical properties. Results showed that the fracture toughness and hardness of the composite tool materials continuously increased with increasing SiC whisker content up to 30 vol.%. The relative density decreased with increasing SiC whisker content, the trend of the flexural strength being the same as that of the relative density. Cutting speeds were found to have a profound effect on the wear behaviors of these ceramic tools. The ceramic tools exhibited relative small flank and crater wear at cutting speed lower than 100 m/min, within further increasing of the cutting speed the flank and crater wear increased greatly. Cutting speeds less than 100 m/min were proved to be the best range for this kind of ceramic tool when machining Inconel718 nickel-based alloys. The composite tool materials with higher SiC whisker content showed more wear resistance. Abrasive wear was found to be the predominant flank wear mechanism. While the mechanisms responsible for the crater wear were determined to be adhesion and diffusion due to the high cutting temperature.     

Effect of coolant strategy on tool performance, chip morphology and surface quality during high-speed machining of A356 aluminum alloy

This paper describes the results of application of different coolant strategies to high-speed milling of aluminum alloy A356 for automotive industry. The paper investigates the effect of flood coolant, dry cutting, and minimum quantity of lubricant (MQL) technologies on tool wear, surface roughness and cutting forces. The cutting speed range was up to 5225 m/min. The feed rate used was up to 20 m/min. The result of MQL application is compared with dry milling and milling with flood coolant application. It was found that the MQL technology could be a viable alternative to the flood coolant application. The adhesive tool wear mechanism and adhesion activated surface quality deterioration are revealed and the role of lubricant in their reduction is defined.     

Evaluation of the performance of CBN tools when turning Ti–6Al–4V alloy with high pressure coolant supplies

Cubic Nitride Boron (CBN) tools are generally used for machining harder alloys such as hardened high Cr steels, titanium and nickel alloys. The tools are expected to withstand the heat and pressure developed when machining at higher cutting conditions because of their high hardness and melting point. This paper evaluates the performance of different CBN tool grades in finish turning Ti–6Al–4V (IMI 318) alloy at high cutting conditions, up to 250 m min⁻¹, with various coolant supplies. Tool wear, failure modes, cutting and feed forces and surface roughness of machined surfaces were monitored and used to access the performance of the cutting tools. Comparative trials were carried out with uncoated carbide tools when machining at a speed of 150 m min⁻¹. Test results show that the performance of CBN tools, in terms of tool life, at the cutting conditions investigated is poor relative to uncoated carbide tools, as expected and often, reported due probably to rapid notching and excessive chipping of the cutting edge associated with a relatively high diffusion wear rate that tends to weaken the bond strength of the tool substrate. An increase in the CBN content of the cutting tool also led to a reduction in tool life when machining at the cutting conditions investigated.     

Modeling and measurement of wear of coated and uncoated high speed steel end mills

A research program was conducted to study tool wear on uncoated and coated (with TiN) high speed steel (HSS) for fluted end mill cutters. These cutters were used to machine AISI 4340 steel at axial and radial engagements of 12.7 mm (0.5 in.). All the machining was carried out using production conditions with the process periodically interrupted to carefully measure the wear condition of the cutting tool. Cutting conditions were carefully chosen so that a linear wear model for the useful life of the cutting tool could be statistically tested. One phase of testing used uncoated tools from 30 different suppliers and the nonstationary linear wear model provided a stochastic representation to determine tool quality using reliability and economic measures. Another phase used the coated tools and a stationary linear wear model to relate force, power, specific cutting energy, and mechanistic model parameters to service life measures. The cutters from each of these phases were carefully examined using optical and scanning electron microscopes so that the dominant wear mechanisms could be identified.     

铍铜合金断续切削后刀面磨损机理研究

目的研究断续切削过程温度变化对刀具粘结现象、涂层剥落和刀具磨损的影响。方法搭建了仿铣削加工的断续车削实验平台,采用热电偶法测量了断续切削过程中刀具后刀面在不同速度下的切削温度,利用带有能谱仪(EDS)的扫描电镜(SEM)观察后刀面随速度变化的磨损形貌并分析后刀面磨损区域的元素组成,阐述了后刀面温度和刀具磨损之间的联系,研究了Ti AlN涂层硬质合金刀具断续切削铍铜合金C17200时的后刀面磨损机理。结果随着切削速度的增加,刀具温度在v=500 m/min出现峰值,温度越高,后刀面的涂层剥落和粘结磨损现象越严重,涂层剥落和粘结磨损现象在切削速度为500 m/min时最严重,而后随着刀具温度的降低而减缓,切削速度600 m/min时的涂层剥落和粘结磨损现象相比500 m/min时有所减轻。结论断续切削过程中,刀具持续性地经受"负载-卸载"、"升温-降温"产生的高温、冲击和加工环境的不稳定性,是引起粘结现象、涂层剥落和刀具磨损的主要原因。涂层剥落和粘结磨损是导致铍铜合金断续切削刀具失效的主要磨损形式。