PCBN刀具切削镍基高温合金刀具磨损的试验研究

通过PCBN刀具对镍基高温合金GH4169进行了车削试验,深入研究了切削时的刀具磨损形态及磨损原因,得出如下结论:通过试验观察看出刀具的磨损形态有前刀面磨损、后刀面磨损、沟槽磨损和刀具破损。其中沟槽磨损最为显著,是刀具失效的主要原因。沟槽磨损的产生原因主要有粘结磨损、扩散磨损和塑性侧流产生的切屑毛刺划擦作用,其中粘结磨损为磨损前期的主要原因,而扩散磨损是磨损后期的主要原因。     

在刀-屑界面持续润滑刀具切削45钢的性能及润滑机理

为提高刀具润滑性能,尽量减少切削液的使用,制备出在刀屑界面持续润滑的新型刀具,能够将切削液通过微通道直接输送到刀屑接触界面内部。采用该新型刀具与普通刀具在干切削和浇注切削液条件下分别进行切削45钢试验,测量了切削三向力,对刀具前刀面磨损面进行SEM微观形貌分析及元素检测,分析了刀具的摩擦磨损特性及润滑机理。试验结果表明,与普通刀具在干切削和浇注切削液条件下相比,刀屑界面持续润滑刀具能够有效减少切削过程中的摩擦磨损,而切削液用量只有传统浇注式切削的1/120。分析前刀面的元素可知,切削液能够更加深入到离主切削刃更近的区域,并能持续供给,这是该刀具具有更好的减摩抗磨效果的主要原因。尽管新型刀具的黏结情况大大缓解,但刀具的磨损机理仍然以黏结磨损和氧化磨损为主。     

钛合金铣削过程刀具前刀面磨损解析建模

钛合金Ti6Al4V作为典型的航空航天难加工材料,在其铣削过程中硬质合金刀具的磨损会降低加工过程稳定性,进而影响加工效率和已加工表面表面质量。刀具前刀面磨损会导致刀具刃口强度降低,并影响切屑的流向和折断情况。针对前刀面磨损机理进行分析并构建了月牙洼磨损深度预测模型。首先运用解析方法构建了前刀面应力场模型,得到切屑在前刀面滑动过程中的刀具前刀面应力分布情况及磨损位置。基于刀-屑接触关系的基础上建立了前刀面温度场模型。然后,基于所得刀具前刀面应力与温度分布,构建综合考虑磨粒磨损、粘结磨损与扩散磨损的铣刀月牙洼磨损深度预测模型,获得月牙洼磨损预测曲线;结合铣刀月牙洼磨损带沿切削刃方向分布的特点,建立了随时间变化的铣刀前刀面磨损体积预测模型。最后通过试验验证了切削宽度对前刀面磨损的影响规律,预测结果与试验测量值具有较好的吻合性。结果表明随着切削宽度的增加,月牙洼磨损深度及前刀面磨损体积都随之增加。研究结果为钛合金铣削用刀具的设计和切削参数的合理选择提供了理论基础。     

纯钒车削刀具磨损表面形态及机理研究

对金刚石刀具、涂层刀具及硬质合金刀具车削纯钒时刀具磨损形态及其磨损机理进行观察和分析.结果表明,在所选取条件下,不同刀具材料对工件材料切削时表现出的刀具磨损形态主要为前刀面磨损、后刀面磨损、微崩刃、剥落和粘结等.刀具的前刀面主要是沿切屑流出方向的沟槽形月牙洼磨损,而后刀面以粘结磨损为主.CD10刀具和H10非涂层刀具具有较佳的切削性能,而H13A非涂层刀具和GC1025涂层刀具不适于纯钒车削.     

硬质合金切槽车刀性能分析

运用有限元方法对钛合金环槽车削过程进行数值模拟计算,得到硬质合金切槽车刀表面的温度,并应用Usui磨损理论计算刀具磨损速率。通过改变切削速度和进给量,获得不同工艺参数下刀具最高温度及刀具前刀面磨损速率。对环槽车削过程的热力耦合模拟结果进行分析,获得刀具切削过程中的温度及磨损速率的变化规律。结果表明,刀具温度和刀具前刀面磨损速率与工艺参数之间存在密切关系,合理选择工艺参数能有效提高硬质合金切槽车刀的性能。     

带卷屑槽刀具最大前角的数学模型与求解

由于现代数控刀具都设计有卷屑槽,从而使其前刀面不是平面,而是曲面。本文针对前刀面为圆柱面的一部分时,采用向量矩阵法建立最大前角计算的数学模型,应用该模型可以在给定条件下,计算曲面型前刀面车刀的最大前角和其它重要的几何参数。最后,给出了计算实例。     

PCD和硬质合金刀具车削钛基复合材料时刀具磨损特征研究

以原位生成晶须和颗粒混合增强钛基复合材料为车削对象,在切削速度为60~120m/min的条件下,对聚晶金刚石（PCD）和硬质合金刀具开展了车削性能试验研究。研究表明,PCD刀具的切削力为硬质合金刀具的77%～88%,其切削温度为硬质合金刀具的65%～82%。无论是高速切削,还是低速切削,PCD刀具都经历初期剧烈磨损而后稳定磨损的过程,而硬质合金刀具仅有急剧磨损的过程。刀具磨损特征方面,PCD刀具主要发生磨粒磨损和黏结磨损,硬质合金刀具主要发生月牙洼磨损、黏结磨损和扩散磨损。     

高速干切削铁基粉末冶金零件时细晶粒硬质合金刀具的切削性能研究

用细晶粒硬质合金刀具进行了铁基粉末冶金零件的高速干切削试验。研究了切削参数与刀具耐用度以及加工表面粗糙度的关系,给出了刀具的主要磨损形态,通过能谱分析研究了刀具的磨损机理。结果表明:所选用细晶粒硬质合金刀具具有较高的刀具耐用度和较好的加工表面粗糙度,适合于铁基粉末冶金的加工;细晶粒硬质合金的主要磨损形态是前刀面的月牙洼磨损;主要磨损机理是扩散磨损、粘结磨损。     

Al_2O_3-TiB_2 刀具的磨损特性

对ＴｉＢ２颗粒增强Ａｌ２Ｏ３刀具在车削正火态、调质态４５＃钢和球墨铸铁齿轮坯时的刀具磨损性能、磨损机理进行了研究，并与硬质合金刀具的耐磨性能进行了对比。结果表明：Ａｌ２Ｏ３┐ＴｉＢ２陶瓷刀具具有良好的耐磨性能。刀具磨损主要以脆性剥离为主，同时存在着犁耕和塑性流变过程，陶瓷刀具表面形成的粘结层结构疏松，与基体结合力较弱，较易脱落，不易形成粘结磨损。     

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。     

基于UG的三维参数化曲面车刀建模及ANSYS强度分析

由于现代数控车刀设计有断屑槽,形成了不同形状的前刀面,本文利用UG强大的三维实体参数化建模的功能,建立了余弦柱面形前刀面车刀.并利用有限元软件ANSYS的分析功能,对相同前角下的余弦柱面形与平面形车刀进行强度分析.通过观察刀头内部应力、应变的大小,得出余弦柱面形前刀面比平面形前刀面车刀的刃磨强度高,为刃磨高强度的车刀提供依据.     

Performance of cutting tools with dimple textured surfaces: A comparative study of different texture patterns

Recently, surface texturing has received much attention as a method of enhancing the tribological properties of a cutting tool surface. However, effective texture patterns and dimensions on a tool surface are still difficult to obtain and suitable textures can be obtained only by trial and error. In order to overcome this problem, we newly develop cutting tools with dimple-shaped textures having different dimensions and arrays, generated on the tool rake face. In addition, we evaluate their crater wear resistance and cutting forces in steel material cutting. Furthermore, under various cutting conditions, the performances of the cutting tools with dimple-shaped textures are compared with those of tools with groove-shaped textures in order to establish a guideline for designing appropriate surface textures on cutting tool surfaces. A series of cutting experiments demonstrate that the dimple textures significantly improve the crater wear resistance and the tribological behavior on the tool rake face, and they exhibit a superior performance compared with those with groove textures, especially in a severely lubricated environment.     

微织构(W,Mo)C基刀具和YG8刀具对钛合金干切削性能的影响

刀具切削钛合金时存在切削温度高、单位面积上切削力大等问题,微织构刀具可以有效减小摩擦力,减小切削力。通过正交实验法设计微织构参数,研究微织构参数对Al 2O 3/La 2O 3/(W,Mo)C无黏结相硬质合金刀具以及YG8刀具切削钛合金实验的切削性能影响。实验结果表明,合适参数的沟槽型微织构能有效降低Al 2O 3/La 2O 3/(W,Mo)C无黏结相硬质合金刀具和YG8刀具切削TC4钛合金的切削力,相同沟槽参数下,无黏结相硬质合金刀具的切削力明显低于YG8刀具的切削力;合适参数的沟槽型微织构能有效降低刀具刀屑界面的摩擦系数,相同沟槽参数下,无黏结相硬质合金刀具的摩擦系数大都低于YG8刀具的摩擦系数;沟槽深度10μm、沟槽间距100μm以及沟槽宽度30μm的沟槽参数下,切削钛合金时,无黏结相硬质合金刀具前刀面无明显磨损,后刀面只有边界磨损,YG8刀具发生崩刃,前刀面出现切屑的滞留。     

Effect of coating layer loss on the wear rate change of coated carbide tools in turning process

This paper reports an experimental study of flank wear on TiN- and TiAlN-coated carbide tools in the turning of AISI 1045, AISI 4135, ductile cast iron, and Inconel 718, and it was conducted with the purpose of showing the relationship between the change in wear rate and the loss of coating layer on the cutting edge. It was found that the relation between cutting distance and flank wear in log-log scale clearly shows the change in wear rate, thus providing a straightforward way to determine the relation between worn out coating layer and increase in wear rate. This relation was confirmed by analyzing the presence of coating layer before and after the inflection point appears by means of scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) photographs. It was observed that the coating layer on the flank face is worn away and finally is worn out. However, even if the layer on the flank face is worn out, tool wear is suppressed as long as the coating layer on the cutting edge exists. On the other hand, when the coating layer on the cutting edge is worn out, the wear resistance of the tool depends on the substrate; thus, the wear rate increases. According to the results, as the cutting speed increases, the change in wear rate appears in a shorter cutting distance, making flank wear to be high. High pressure and high temperature act on the rake face; thus, thermal stability of the coating layer in the cutting edge is important. A low cutting speed decreases cutting efficiency, but a high cutting speed causes flank wear to be high; therefore, in order to optimize machining cost, an acceptable cutting speed, from the standpoint of tool wear, should be selected.     

Tool wear and its effect on surface roughness in diamond cutting of glass soda-lime

For the technology of diamond cutting of optical glass, the high tool wear rate is a main reason for hindering the practical application of this technology. Many researches on diamond tool wear in glass cutting rest on wear phenomenon describing simply without analyzing the genesis of wear phenomenon and interpreting the formation process of tool wear in mechanics. For in depth understanding of the tool wear and its effect on surface roughness in diamond cutting of glass, experiments of diamond turning with cutting distance increasing gradually are carried out on soda-lime glass. The wear morphology of rake face and flank face, the corresponding surface features of workpiece and the surface roughness, and the material compositions of flank wear area are detected. Experimental results indicate that the flank wear is predominant in diamond cutting glass and the flank wear land is characterized by micro-grooves, some smooth crater on the rake face is also seen. The surface roughness begins to increase rapidly, when the cutting mode changes from ductile to brittle for the aggravation of tool wear with the cutting distance over 150 m. The main mechanisms of inducing tool wear in diamond cutting of glass are diffusion, mechanical friction, thermo-chemical action and abrasive wear. The proposed research makes analysis and research from wear mechanism on the tool wear and its effect on surface roughness in diamond cutting of glass, and provides theoretical basis for minimizing the tool wear in diamond cutting brittle materials, such as optical glass.     

前刀面槽型结构对D型刀片车削球墨铸铁性能的影响

通过切削力、磨损和冲击切削试验,研究了前刀面槽型结构对D型刀片车削球墨铸铁切削性能的影响。试验结果显示,刀具的第一前角对切削力的影响最大;在10°~15°范围内,刀具前角越大,切削力越低;棱带宽度大的刀片具有更加优异的耐磨损性能;具有正刃倾角的刀片显示出更优异的耐冲击性能。     

Prediction of cutting temperature distributions on rake face of coated cutting tools

Coated cutting tools have been widely employed in metal cutting operations owing to its excellent abrasion resistance and heat transfer performances. Rake face temperature is the primary factor that determines the temperature distribution in the cutting tool body. Based on the heat source theory, a new prediction model is proposed in this paper to forecast the temperature distribution on the rake face. Infrared image is used to develop a new turning experimental apparatus to measure the rake face temperature of coated tool during the cutting process. Rake face temperature measurement results are used to verify the proposed model prediction results of temperature distribution. Several cutting tests are carried out with monolayer coated tools in the machining of H13 hardened steel. The rake face temperature in monolayer coated tool for machining H13 shows an increase trend as the cutting speed increases. The influence parameters including thermo-physical properties and tool/workpiece frictional coefficient of coating material on temperature distribution in coated tools are discussed and illustrated. The research results presented in this paper can help to access the potential of coated tools used in the hardened steel machining.     

An empirical survey on the influence of machining parameters on tool wear in diamond turning of large single-crystal silicon optics

We conducted a series of screening experiments to survey the influence of machining parameters on tool wear during ductile regime diamond turning of large single-crystal silicon optics. The machining parameters under investigation were depth-of-cut, feed rate, surface cutting speed, tool radius, tool rake angle and side rake angle, and cutting fluid. Using an experimental design technique, we selected twenty-two screening experiments. For each experiment we measured tool wear by tracing the tool edge with an air bearing linear variable differential transformer before and after cutting and recording the amount of tool edge recession. Using statistical tools, we determined the significance of each cutting parameter within the parameter space investigated. We found that track length, chip size, tool rake angle and surface cutting speed significantly affect tool wear, while cutting fluid and side rake angle do not significantly affect tool wear within the ranges tested. The track length, or machining distance, is the single most influential characteristic that causes tool wear. For a fixed part area, a decrease in track length corresponds to an increase in feed rate. Less tool wear occurred on experiments with negative rake angle tools, larger chip sizes and higher surface velocities. The next step in this research is to perform more experiments in this region to develop a predictive model that can be used to select cutting parameters that minimize tool wear.     

Preparation of tungsten disulfide (WS2) soft-coated nano-textured self-lubricating tool and its cutting performance

This paper proposes a new effective dry cutting tool named tungsten disulfide (WS₂) soft-coated nano-textured self-lubricating tool which is fabricated by two steps. First, nano-texture is made on the tool–chip interface of rake face of uncoated YS8 (WC + TiC + Co) cemented carbide cutting inserts by femtosecond laser micromachining technology. Second, WS₂ soft coating is deposited on the nano-textured tool by medium-frequency magnetron sputtering, multi-arc ion plating and ion beam assisted deposition technique. Dry turning tests on 45# quenched and tempered steel were carried out with three kinds of cutting tools: conventional YS8 tool, nano-textured tool (CFT), and WS₂ soft-coated nano-textured self-lubricating tool (CFTWS). Results show that the cutting forces, cutting temperature, the friction coefficient at the tool–chip interface, and the antiadhesive effect of the nano-textured tools were significantly reduced compared with those of the conventional one. The CFTWS tool had the best cutting performance among all the tools tested under the same test conditions. Through cutting force and cutting temperature theoretical analysis and experimental results, four mechanisms responsible were found. The first one is explained as the formation of the WS₂ lubricating film with low shear strength at the tool–chip interface, which was released from the surface nano textures and smeared on the rake face, and served as lubricating additive during dry cutting processes to reduce the cutting forces and cutting temperature. The second one is explained by the reduced contact length at the tool–chip interface of the nano-textured tools; the smaller direct contact area between the chip and tool rake face leads to less friction force, which can also contribute to the decrease of cutting forces and cutting temperature. The third one can be explained that because of the excellent lubricity of the WS₂ lubricating film, the antiadhesive effect can be significantly improved which can reduce adhesive wear of the cutting tool and prolong the tool life. The fourth one can be explained that the advantage of CFTWS tool in cutting forces and cutting temperature is obvious in relatively high-speed and high-temperature conditions may be because of ultra-low friction coefficient, high temperature resistance, and the high oxidation resistance of WS₂ soft coating which is not sensitive to high cutting temperature and high cutting speed can significantly improve the severe dry cutting environment.     

Statistical analysis of process parameters in drilling of AL/SICP metal matrix composite

Four micro-holes were made using micro-EDM on rake face of the cemented carbide (WC/TiC/Co) tools. MoS₂, CaF₂, and graphite solid lubricants were respectively embedded into the four micro-holes to form self-lubricated tools (SLT-1, SLT-2, and SLT-3). Dry machining tests on hardened steel were carried out with these self-lubricated tools and conventional tools (SLT-4). The cutting forces, average friction coefficient between tool and chip, and tool wear were measured and compared. It was shown that the cutting forces and tool wear of self-lubricated tools were clearly reduced compared with those of the SLT-4 conventional tool. The SLT-1 self-lubricated tool embedded with MoS₂ just exhibited lower friction coefficient between tool and chip in cutting speed of less than 100?m/min; the SLT-2 self-lubricated tool embedded with CaF₂ possessed lower friction coefficient in cutting speed of more than 100?m/min; and the SLT-3 self-lubricated tool embedded with graphite accomplished good lubricating behaviors steadily under the test conditions. It is indicated that cemented carbide inserts with four micro-holes on rake face embedded with appropriate solid lubricants on rake face is an effective way to reduce cutting forces and rake wear.