金属陶瓷刀具切削性能的研究

本文研究了纳米TiN改性的TiC基金属陶瓷刀具和超细晶Ti(C,N)基金属陶瓷刀具切削正火态45#钢的切削性能,尝试用SPSS11.5软件对正交试验的数据进行分析。结果表明,这两种刀具的最佳切削条件均为vc=200m/min,ap=0.3mm,f=0.1mm/r。最后分析了它们切削45#钢的磨损机理。     

硬质合金铣刀铣削性能研究

为了探讨国内外高端产品的质量水平,为国产硬质合金铣刀性能提升提供有益的指导,对比研究了国内外知名品牌铣刀的耐磨性和失效形式。采用端面中心对称干切削方式,按照实验室铣刀试验规范对相同材质的国产某品牌刀片和国外刀片在相同工艺条件下进行了铣削对比实验,工件材料为45#钢。实验结果表明:两种刀片高速干式铣削45#钢的寿命没有明显差异。国产刀片失效形式主要为磨损失效,其在45#钢的高速干式铣削上显示出了较高的耐磨性;国外刀片同时表现出崩刃失效。     

超细晶粒Ti（C，N）基金属陶瓷刀具切削性能

利用真空烧结工艺制备了两组含有不同TiN成分的超细晶粒Ti(C,N)基金属陶瓷可转位刀片,用不同的切削速度和进给量切削正火45钢,分析了刀具的耐用度、磨损和失效方式等切削性能.结果表明:高速切削时刀具的磨损形式以氧化磨损和扩散磨损为主;在高速进给量大的切削条件下,含TiN低的刀片切削性能好于TiN高的刀片;切削速度对刀具寿命的影响很大;进给量在切削速度较低时对刀具寿命的影响程度要大于切削速度较高时.     

波形刃铣削刀片的磨损特性实验研究

本文通过调质45钢的铣削加工实验,对比研究了波形刃铣削刀片和直线刃铣削刀片的磨损特性,分析了铣削过程中刀具磨损对铣削力的影响规律;利用影像仪和扫描电子显微镜对磨损后的刀片进行观察,研究了两种刀片的磨损形态和磨损机理。实验结果表明:单齿铣削时,直线刃铣刀的铣削力和磨损值均小于波形刃铣刀;双齿铣削时,波形刃铣刀铣削性能优于直线刃铣刀,不仅单点铣削力小,而且具有良好的分屑及散热效果,铣削超过50 min后其磨损量约为直线刃铣刀磨损量的70%。波形刃铣刀多齿铣削具有良好的铣削性能。     

PVD涂层刀具高速铣削CoCrMo合金的性能研究

目的为了提高涂层硬质合金刀具的切削性能,研究了物理气相沉积PVD法制备的涂层硬质合金铣刀在高速干式环境下的铣削性能。方法采用阴极电弧技术制备了TiN、TiAlN以及TiAlSiN涂层硬质合金铣刀刀头,通过一同沉积涂层的硬质合金圆片,间接测量得出涂层的显微硬度、厚度和平均摩擦系数,并以CoCrMo合金为切削对象,进行了PVD涂层与无涂层刀具高速铣削下的对比试验。结果TiAlSiN显微硬度最高达3800HV,摩擦系数达0.3,TiAlN涂层平均膜厚为2μm,间接测得TiN、TiAlN以及TiAlSiN涂层的结合力依次为60、58、42N。在三者的切削性能中,TiAlSiN涂层的切削性能比TiAlN和TiN涂层的好,同等切削参数时,TiN刀具的高速铣削时间最短,TiAlSiN涂层的平均磨损值为0.1895,TiN的平均磨损值为0.3047。结论涂层中添加Al、Si,极大地提高了刀具的使用性能,改善了刀具切削过程中的耐磨性、红硬性,极大地延长了刀具的使用寿命。TiAlSiN涂层的硬度高,耐磨损性好,切削性能好,适合高速铣削加工。     

微细铣削中刀具侧刃磨损试验研究

随着科学技术的发展,微小零件广泛应用于各个领域,而微细铣削技术变得越来越重要。在微细铣削中,对刀具磨损的研究占有重要地位。采用直径1 mm的TiAlN涂层平头铣刀,针对微细铣削黄铜H59时的刀具侧刃磨损进行试验研究。发现随着铣削长度的增加,侧刃磨损量呈上升趋势。切削长度为200 m时,两组试验的磨损带宽度变化由快变慢,出现变化临界点。对刀具磨损形式与机制进行分析,发现刀具出现涂层脱落、刀尖钝圆半径变大和微崩刃现象,分析其发生机制为磨粒磨损与粘结磨损。以侧刃后刀面磨损带宽度为试验指标进行正交试验,研究铣削参数对刀具侧刃后刀面磨损的影响主次顺序及最优参数组合。结果表明:每齿进给量、轴向切深、主轴转速和径向切深对刀具磨损的影响依次减少;试验所得最优参数组合为f_z=2μm/齿,a_p=0.3 mm,n=60 000 r/min,a_e=0.15 mm。     

金属陶瓷刀具切削淬火钢的磨损机理研究

利用真空烧结工艺制备了纳米复合TI(C,N)基金属陶瓷刀片.进行淬火态45#钢的单因素切削试验,并利用SEM,EPMA对金属陶瓷刀具的磨损失效机理进行了研究.结果表明纳米复合TI(C,N)基金属陶瓷刀片在切削淬火态45#钢时表现出较高的耐磨性和切削性能,其主要的磨损失效机理是压应力下的挤压变形和粘附磨损,同时伴随一定的氧化磨损和扩散磨损.     

TiN/TiAlN涂层Ti(C,N)基金属陶瓷刀具的切削性能

采用多弧离子镀技术在Ti(C,N)基金属陶瓷基体上沉积了TiN/TiAlN多层涂层,通过扫描电镜、涂层附着力自动划痕仪对其显微组织形貌和涂层的结合强度进行了分析,并对涂层和未涂层金属陶瓷铣刀以及硬质合金铣刀进行了切削0Cr18Ni9钢的试验.结果表明,多弧离子镀TiN/TiAlN涂层均匀,TiN/TiAlN多层涂层与金属陶瓷之间的结合强度高达57.52 N.TiN/TiAlN涂层金属陶瓷的切削性能明显优于未涂层金属陶瓷和硬质合会YW2,其平均寿命为硬质合金刀具的2倍.TiN/TiAlN涂层金属陶瓷刀具的失效形式主要是磨损和崩刃,没有涂层剥落现象,TiN/TiAlN涂层与基体的结合强度很好.未涂层金属陶瓷刀具的磨损形式主要是磨损和粘着.     

TiN和TiAlN涂层刀具铣削铝锂合金表面质量试验对比研究

目的 比较TiN和TiAlN涂层刀具加工铝锂合金的切削性能和表面质量。方法 使用硬质合金、TiN涂层和TiAlN涂层三种刀具，对2198-T8型铝锂合金进行干式铣削试验。改变切削因素的水平，比较刀具磨损、铝锂合金的表面粗糙度、切削力和切屑形态。结果 铣削铝锂合金时，刀具主要磨损为粘附磨损，TiN涂层的粘附程度最低，硬质合金次之，TiAlN涂层表面粘附最严重，切削效能最低。粘附磨损严重影响铣削成形的表面粗糙度，并使铣削力增加。铣削速度是影响工件表面粗糙度的主要因素，通过提高铣削速度可明显降低材料的粘结程度，降低表面粗糙度与铣削力，TiN涂层在铣削铝锂合金时最小表面粗糙度可达到0.5 μm以下。在相同的切削参数下，TiN涂层断屑均匀，切屑表面较为光滑，切屑塑性变形最小。硬质合金刀具产生的切屑尺寸较短，切屑表面有少量带状条纹，TiAlN涂层刀具产生的切屑发生了严重的塑性变形。结论 与TiAlN涂层和硬质合金刀具相比，TiN涂层刀具在铣削铝锂合金时的切削效能最好，可以达到最好的表面粗糙度和加工效果。     

超声振动铣削碳纤维复合材料刀具磨损研究

介绍了采用超声振动铣削和普通铣削对硬质合金铣刀铣削碳纤维复合材料进行试验研究。试验结果表明,在两种加工方式下,刀具的磨损形式主要是后刀面磨损,前刀面磨损和刀刃的破损,其中后刀面的磨粒磨损最严重,前刀面的粘着磨损较弱,当进给量加大或者是主轴转速过高时,很容易发生崩刃。超声振动条件下,刀具的后刀面磨损和前刀面磨损均较弱,且呈现一定的规律性。刀具的耐用度高,相对于普通切削更适合于复合材料的加工。     

Tool wear mechanism of WC–5TiC–10Co ultrafine cemented carbide during AISI 1045 carbon steel cutting process

WC–5TiC–10Co ultrafine and conventional cemented carbides were prepared and used for AISI 1045 carbon steel cutting tool inserts. The microstructure and mechanical properties were characterized, and cutting tests were conducted with different cutting parameters. Tool wear mechanism was analyzed by SEM and EDS. Ultrafine inserts possess higher hardness and transverse rupture strength. There were adhesive wear on the rake and slight abrasive wear on the flank of ultrafine inserts. As for conventional inserts with the same composition but with medium grain size, there were combinations of more serious abrasive and adhesive wear on the rake and flank.     

High bandwidth temperature measurement in interrupted cutting of difficult to machine materials

High-speed milling is used across industries from aerospace to electronics. Tool wear can be affected by cutting interruptions in milling that lower tool-chip interface temperatures but also cause thermal and stress cycling. Micro-thermal imaging was used to determine the temperature during interrupted cutting of titanium alloy Ti6Al4V and AISI 4140 steel for percentage of time-in-cut from 100% to 10%. TiAlN/TiN coated carbide milling inserts were used with cutting speeds up to 180 and 640 m min⁻¹. This technique is the first to allow spatial mapping of thermal fluctuations on the tool which may be critical to determining causes for tool failure.     

Milling performance of TiC-Ni cermet tools toughened by TiN nanoparticles

A novel indexable TiC-based cermet tool (named tool A) with intra/intergranular microstructure has been designed and fabricated in application of face milling of a medium carbon steel (AISI 1045) in the dry condition comparison with commercial WC-Co tool (named tool B). Compared to the tool B, the newly as-prepared cermet tool A had an advantage of high speed cutting performances in cutting carton steel. Wear behavior was investigated in order to better understand the relationship between outstanding cutting properties and microstructure. The improved cutting performance of tool A can be attributed to the rim reinforced by TiN nanoparticles.     

Cutting performance of PVD-coated carbide and CBN tools in hardmilling

In this study, cutting performance of CBN tools and PVD-coated carbide tools in end-milling of hardened steel was investigated. In high-speed dry hardmilling, two types of CBN tools were applied: the CBN-rich type and an ordinary one. In the case of relatively low-speed milling, on the other hand, a few coated carbide tools were selected where four kinds of coating films, TiN, TiCN, TiAlN and multi-layered TiAlN/AlCrN, were deposited on the K10 and P30 grade carbide. The cutting performance was mainly evaluated by tool wear, cutting temperature, cutting force and surface roughness. In dry cutting of hardened carbon steel with the ordinary CBN tool, the cutting tool temperature rose rapidly with increase in cutting speed; and tool temperature reached approximately 850 °C at the cutting speed of 600 m/min. In the case of the CBN-rich tool, the cutting temperature decreased by 50 °C or more because of its high thermal conductivity. It is remarkable that tool wear or damage on a cutting tool was not observed even when the cutting length was 156 m in both CBN tools. In the case of coated carbide tools, the temperatures of TiN-, TiCN- and TiAlN-coated carbide tools rose as cutting proceeded because of the progress of tool wear, but that of TiAlN/AlCrN-coated carbide tool hardly rose due to little tool wear. When the base material was K10 grade carbide, tool temperature was lower than that of P30 with any coating. The tool flank wear depends considerably on hardness and oxidizing temperature of the coating film.     

Cutting performances, mechanical property and microstructure of ultra-fine grade Ti(C, N)-based cermets

The two cutting tools obtained from ultra-fine grade Ti(C, N)-based cermets were tested in the dry cutting of a medium carbon steel (AISI1045). Microstructure and mechanical properties were studied. Wear mechanisms (mainly diffusion and oxidation) were investigated in detail and compared each other in order to better understand key aspects due to thermal wear mechanisms. Comparing tool A with B, under the adopted cutting conditions, the tool A has a better resistance to oxidation deformation in machining medium carbon steel due to the higher hardness, although tool B has higher bending strength and fracture toughness.     

Tool wear control in single-crystal diamond cutting of steel by using the ultra-intermittent cutting method

Excessive tool wear is a major drawback to the ultraprecision cutting of steel with geometrically defined single-crystal diamond tools. This paper presents a new approach to reduce this wear. In general, the wear of the diamond tool is due to chemical reactions such as diffusion into the steel, oxidation, graphitization, and carbide formation under cutting conditions of high temperature and high pressure. To suppress these types of chemical reactions, the contact time between the diamond tool and the steel in the cutting process was controlled by intermittent cutting method such as fly-cutting or milling. A series of intermittent cutting experiments were carried out to control the tool–workpiece contact time in one cutting cycle by changing the cutting speed and cutting length in each cutting cycle. The experimental results showed that the diamond tool wear was highly dependent on the tool–workpiece contact time, regardless of the cutting speed, and that the wear was greatly reduced by decreasing the contact time to less than 0.3 ms under these cutting conditions. It is expected that steel can be successfully cut with a single-crystal diamond tool by controlling the tool–workpiece contact time.     

Investigation of the effects of cryogenic treatment applied at different holding times to cemented carbide inserts on tool wear

Cutting tool costs is one of the most important components of machining costs. For this reason, tool life should be improved using some methods such as cutting fluid, optimal cutting parameters, hard coatings and heat treatment. Recently, another one of the methods commonly used to improve tool life is cryogenic treatment. This study was designed to evaluate the effects of different holding times of deep cryogenic treatment on tool wear in turning of AISI 316 austenitic stainless steel. The cemented carbide inserts were cryogenically treated at −145 °C for 12, 24, 36, 48 and 60 h. Wear tests were conducted at four cutting speeds (100, 120, 140 and 160 m/min), a feed rate of 0.3 mm/rev and a 2.4 mm depth of cut under dry cutting conditions. The wear test results showed that flank wear and crater wear were present in all combinations of the cutting parameters. However, notch wear appeared only at lower cutting speeds (100 and 120 m/min). In general, the best wear resistance was obtained with cutting inserts cryogenically treated for 24 h. This case was attributed to the increased hardness and improved micro-structure of cemented carbide inserts. These improvements were confirmed through hardness, image processing, and XRD analyses.     

Evolution of residual stress and damage in coated hard metal milling inserts over the complete tool life

In coated hard metal milling inserts the main damage mechanisms are thermal fatigue induced by interrupted tool–workpiece contact and wear. Dependent on the magnitudes of thermal and mechanical loads in two applied test setups, either wear or thermal fatigue in the form of combcracks is induced. The evolution of residual stress and damage in the used milling inserts was documented over their complete lifetime. In a region of interest on the tool rake face a significant buildup of tensile residual stress was observed via a synchrotron based technique. A special preparation technique enabled position resolved measurements in this area by in-house X-ray diffraction facilities to study the evolution of residual stress over the entire tool lifetime. The onset of cracking was observed to happen in this region of interest by means of focused ion beam milling and scanning electron microscopy. The residual stress levels observed are comparable in used inserts at early stages of application, independent of the different cutting conditions and the applied characterization technique. At the end of tool life wear damage dominated inserts showed tensile residual stress, whereas thermal fatigue as the dominant damage mechanism resulted in compressive residual stresses.     

An experimental study of tool wear and cutting force variation in the end milling of Inconel 718 with coated carbide inserts

Inconel 718 is a difficult-to-cut nickel-based superalloy commonly used in aerospace industry. This paper presents an experimental study of the tool wear propagation and cutting force variations in the end milling of Inconel 718 with coated carbide inserts. The experimental results showed that significant flank wear was the predominant failure mode affecting the tool life. The tool flank wear propagation in the up milling operations was more rapid than that in the down milling operations. The cutting force variation along with the tool wear propagation was also analysed. While the thermal effects could be a significant cause for the peak force variation within a single cutting pass, the tool wear propagation was believed to be responsible for the gradual increase of the mean peak force in successive cutting passes.     

硬质合金涂层刀片铣削AISI410不锈钢刀具寿命研究

AISI410不锈钢广泛应用于各种工业设备的制造,如汽轮机叶片,各种泵的机械零件和蒸汽设备等。加工过程中存在着导热率低、加工硬化严重、切削力大等问题,属于典型的难加工材料。本文通过硬质合金涂层刀片铣削AISI410不锈钢正交试验,研究了硬质合金涂层刀片铣削AISI410不锈钢时刀具寿命的变化规律,归纳了相应的刀具寿命模型,并对其中的各影响因素的独立作用效果进行了分析。试验结果表明:硬质合金涂层刀片加工AISI410不锈钢时,铣削方式、每齿进给量、切削速度、轴向切削深度对刀具寿命的影响依次减小;切削速度越低,每齿进给量对于刀具寿命的影响越大;切削效率一定时,降低切削速度增大每齿进给量有利于延长刀具寿命。