PCBN刀具切削性能和磨损机理研究综述

聚晶立方氮化硼(PCBN)刀具是继聚晶金刚石刀具之后的又一种超硬刀具,以其独特的“以车代磨”、“硬态加工”、“干式切削”等方式被誉为21世纪的绿色环保刀具。PCBN刀具在金属切削方面具有广泛的应用,主要用来加工各种淬硬钢、耐磨铸铁等铁基材料。本文介绍了PCBN刀具成分、几何形状、切削参数等对其切削性能的影响,在此基础上分析了不同材料加工时刀具的主要磨损机理,还简单对比了硬质合金和PCBN刀具切削性能上的差异。      

氮化铬铝涂层PCBN刀具旋风硬铣切屑宏观特征研究

氮化铬铝具有比氮化钛铝更高的硬度和抗氧化性,能否作为PCBN刀具的涂层需要进行试验研究验证.通过对氮化铬铝涂层PCBN刀具在硬态旋风铣削淬硬钢GCr15平均硬度为63.5HRC)加工中,选用不同的切削参数、冷却方式和刀具个数的研究,从而得出氮化铬铝涂层PCBN刀具旋风硬铣加工的特点和应用范围,对涂层刀具的研究和切屑预报研究提供了依据.     

PCBN刀具材料与现代加工技术

随着科技的不断发展,对一些更坚固、更轻、更耐磨材料的需求也在不断增加,在现代工业尤其是汽车工业及航天航空工业中,复合材料及耐磨有色金属材料被大量使用,而采用普通刀具加工这类材料却难以胜任。因此,超硬刀具材料PCBN应运而生。本文对PCBN刀具用于高速与超高速切削、硬态干式切削、在数控机床上加工淬火钢加工以及不同应用领域对PCBN刀具材料的要求均有描述。指出,为达到我国未来工业经济的高速发展,超硬刀具的成功应用是一个关键因素。     

AISI 4340高强钢高速硬车削下PCBN刀具磨损机理

PCBN刀具在硬切削加工中磨损严重,探究PCBN刀具的磨损机理,能够为改善刀具切削性能、提高加工效率提供指导.采用PCBN刀具进行高速硬车削AISI 4340高强钢试验,研究不同切削速度下的PCBN刀具的磨损形式及磨损机理.通过对比三种切削速度(v=150 m/min、210 m/min、300 m/min)切削两种硬...     

PCBN刀具干湿切削加工淬硬钢时的磨损对比

本文研究了在一定切削参数下干、湿式切削加工淬硬钢时四种PCBN刀具的刀具寿命、磨损形式和磨损机理。通过扫描电子显微镜观察不同切削行程下刀尖形貌和刀具后刀面磨损量,并对刀具前后刀面进行能谱分析。结果表明湿式切削时的后刀面磨损量小于干式切削,说明刀具湿切比干切时具有较好的性能;PCBN刀具的磨损形式有前刀面磨损、后刀面磨损,其中前刀面磨损的表现形式为月牙洼磨损,磨损机理为机械磨损、氧化磨损和黏结剂磨损,而后刀面磨损机理有机械磨损、氧化磨损、黏结剂磨损和扩散磨损等;同时还发现CBN含量下降,刀具的后刀面磨损量也有下降趋势,即刀具的切削寿命有延长趋势。     

不同PCBN刀具车削硼铸铁的对比研究

使用不同的立方氮化硼刀具材料(PCBN)和刀具结构,在相同加工参数下,对硼铸铁进行切削加工试验,并对比其加工效果。结果表明:同粗粒度的PCBN刀具相比,细粒度的PCBN刀具加工所得的工件表面粗糙度较低,且刀具本身的耐磨性较高;在切削过程中,随着进给量的增大,工件表面粗糙度也增大;PCBN刀具的负倒棱宽度对加工硼铸铁的切削温度和后刀面磨损有较大影响,负倒棱宽度增加,切削温度和刀具磨损增加,而倒棱角度对刀具和切削过程影响有限。     

PCBN刀具高速切削淬硬钢材料的研究

以PCBN复合片为刀具材料进行相关力学性能分析,并将其制成SNGN120408型刀具后在刀具机床上进行淬硬钢切削试验.分析结果表明:PCBN复合片的结合剂主要为TiN和TiB2,其内部结构均匀,且有良好的致密性.切削试验表明:在干式切削淬硬钢的试验中,切削进给量以及切削速度对PCBN刀具的磨损有较为明显的影响.相比于切...     

PCBN刀具几何参数对高速干切削淬硬轴承钢寿命的影响

本文选取美国公司的BZN9000刀片为研究对象,在CA6140A车床上对GCr15淬硬轴承钢轴承环外套进行了一系列高速硬态干切削实验。采用正交试验设计方法,研究了PCBN刀具几何参数对其使用寿命的影响。结果表明:倒棱角度为-15°、刀尖圆弧半径为0.8 mm、后角度数为6°时,PCBN刀具的寿命最长,并得出刀具寿命影响程度大小的顺序依次为倒棱角度、刀尖圆弧半径和后角。     

切削速度与进给量对UVC硬态切削加工的影响

阐述了超声振动切削(Ultrasonic Vibration Cutting,UVC)的加工机制,并通过理论计算研究了切削速度对加工过程的影响,同时对Incone1718硬态合金进行UVC加工和传统车削法加工(Conventional Turning Method,CT),研究了切削速度与进给量对刀具切削性能的影响.实验结果表明:在进行低速硬态切削时,UVC在切削表面质量和刀具寿命方面均优于CT;同时切削速度和进给量对切削力和刀具磨损都有显著影响,与理论研究结果相符.     

PcBN刀具材料在高速硬态切削中的应用研究

简要介绍了PcBN刀具材料的高压高温烧结制备方法及其物理力学性能特点、高速切削技术与硬态切削技术的特点以及PcBN刀具材料对高速硬态加工的适应性。分析和探讨了高速硬态切削对PcBN材料性能的要求,认为限制PcBN应用于高速硬态切削的主要是其高温力学性能,包括高温强度、高温硬度、高温韧性等。介绍了目前国外高速切削用PcBN材料的研究新进展,列举了PcBN刀具应用于高速硬态加工领域的实例,指出纳米级无任何粘结剂的PcBN刀具材料的开发与应用对推动我国的高速切削加工技术具有十分重要的意义。     

Effect of chamfer angle on wear of PCBN cutting tool

In precision hard turning, a remaining problem is to minimise tool wear to maintain the accuracy of geometry and surface finish. Tool wear not only directly reduces the part geometry accuracy but also increases cutting forces drastically. The change in the cutting forces also causes instability in the tool motion, which results in more inaccuracy. PCBN cutting tools are often used in hard turning. However, they are still relatively expensive compared to ordinary carbide cutting tools. In order to attain sufficiently high production rates at minimum cost, increase of knowledge on cutting tool geometry is necessary. This article presents a study of the effect of chamfer angle on tool wear of PCBN cutting tool in the super finishing hard turning. The correlation between cutting force, tool wear and tool life were investigated. The optimised chamfer angle for PCBN cutting tool is suggested. Finally, the distribution of stresses and maximum principal stress working on the tool edge were calculated with the use of finite element method.     

Tool wear and machining performance of cBN–TiN coated carbide inserts and PCBN compact inserts in turning AISI 4340 hardened steel

PCBN is the dominant tool material for hard turning applications due to its high hardness, high wear resistance, and high thermal stability. However, the inflexibility of fabricating PCBN inserts with complex tool geometries and the prohibitive cost of PCBN inserts are some of the concerns in furthering the implementation of CBN based materials for hard turning. In this paper, we present the results of a thorough investigation of cBN plus TiN (cBN–TiN) composite-coated, commercial grade, carbide inserts (CNMA 432, WC–Co (6% Co)) for hard turning applications in an effort to address these concerns. The effect of cutting speed and feed rate on tool wear (tool life), surface roughness, and cutting forces of the cBN–TiN coated carbide inserts was experimented and analyzed using analysis of variance (ANOVA) technique, and the cutting conditions for their maximum tool life were evaluated. The tool wear, surface roughness, and cutting forces of the cBN–TiN coated and commercially available PCBN tipped inserts were compared under similar cutting conditions. Both flank wear and crater wear were observed. The flank wear is mainly due to abrasive actions of the martensite present in the hardened AISI 4340 alloy. The crater wear of the cBN–TiN coated inserts is less than that of the PCBN inserts because of the lubricity of TiN capping layer on the cBN–TiN coating. The coated CNMA 432 inserts produce a good surface finish (<1.6 μm) and yield a tool life of about 18 min per cutting edge. In addition, cost analysis based on total machining cost per part was performed for the comparison of the economic viability between the cBN–TiN coated and PCBN inserts.     

PCBN刀具的切削性能及其应用

文章阐述了PCBN刀具的切削性能和在实际应用中应该注意的问题,为在机械加工行业中推广应用PCBN刀具作初步的探讨.     

PCBN刀具干湿切削淬硬钢表面完整性研究

本文以采用PCBN刀具切削淬硬轴承钢GCr15为试验，对干、湿切削两种润滑条件下，工件表面粗糙度及表面白层（一种在加工表面形成的晶相组织发生变化的结构）进行了对比研究。实验结果表明：干、湿切削都可获得较好的表面粗糙度，湿切削表面粗糙度Ra稍低；湿切削没有发现明显的白层产生，干切削白层生成较早，且白层与黑层的厚度随着刀具磨损的增加而逐渐增加。     

Surface finish on hardened bearing steel parts produced by superhard and abrasive tools

New technological process consisting of hard turning (HT) followed by abrasive machining, in place of the widely used method in industry, i.e., hard turning versus grinding, has lately been launched in the automotive industry. This is because, many transmissions parts, such as synchronizing gears, crankshafts and camshafts require superior surface finish along with appropriate fatigue performance. This paper provides a comprehensive characterization of part surface finish produced in dry turning of a hardened AISI 52100 bearing steel using mixed ceramic (MC) and PCBN tools, and also its modification after special abrasive finishing operations including superfinishing (SF) and belt grinding (BG). In this investigation, some important 2D and 3D surface roughness parameters, as well as profile and surface characteristics, such as the amplitude distribution functions, bearing area curves, surface topographies and contour maps obtained for the four surface types selected, were determined and analyzed. Experimental data gained during measurements indicate that each of the finishing abrasive processes provides a specific set of surface topologies. The transformation of bearing properties of surfaces, generated through two optional PCBN HT-BG and MC HT-SF machining sequences, are highlighted. As a result, the modifications of surface profiles achieved by means of special abrasive machining operations can distinctly improve the bearing properties of previously hard turned surfaces, and exemplarily, they shorten the running-in period.     

Surface finish generated in hard turning of quenched alloy steel parts using conventional and wiper ceramic inserts

Significant progress has already been achieved in green manufacturing including dry and hard, often high-speed, machining technologies. For instance, the demand for higher productivity has resulted in the wider application of ceramic and PCBN tools with special multi-radii (wiper) geometry. This paper reports some important characteristics of the surface roughness produced in the turning of a hardened low-chromium alloy steel using mixed alumina–titanium carbon (TiC) ceramic cutting tools equipped with both conventional and wiper inserts. The characteristic geometrical features of surfaces obtained in both these turning operations have been assessed by means of representative two-dimensional (2D) surface roughness parameters, and some 3D visualizations, which allowed more complete characterization of the surface topography and prediction of its service properties. Results show that keeping equivalent feed rates, i.e. 0.1 mm/rev for conventional and 0.2 mm/rev for wiper tools, the surfaces obtained have similar 3D height roughness parameters, and comparable values of skew and kurtosis. At defined cutting parameters, surfaces produced by wiper tools contain blunt peaks with distinctly smaller slopes resulting in better bearing properties. Only marginal changes of Ra parameter were recorded during 15 min machining trials.     

PCBN刀具断续车削淬硬钢的试验研究

为了探索PCBN刀具在断续切削条件下刀具的破损规律,选用两种不同的PCBN刀具,在不同强度的断续方式及不同的切削速度下,对淬硬钢进行车削试验研究。根据试验条件,观察了刀具前、后刀面的磨损及破损情况,分析了刀具的失效机理,比较了刀具的切削寿命。结果表明：断续强度严重影响PCBN刀具的使用寿命,断续强度越高,刀具寿命越低;在相同强度的断续条件下,切削速度影响刀具的使用寿命,切削速度越高,刀具的寿命越低;本实验所用的断续条件下,刀具的失效判据为崩刃。     

Evaluation of layer adhered on PCBN tools during turning of AISI D2 steel

Polycrystalline cubic boron nitride (PCBN) tools have high abrasion resistance and are thus suitable for application in the machining of steels with a high volume fraction of primary carbides in their microstructure. These tools are usually applied in the machining of steels with hardness above 45–50 HRC and in the case of application to steels with hardness below 45 HRC, the formation of an adhered layer on the rake face of the tools often occurs. This paper reports a study on the impact of the layer adhered on PCBN tools during the turning of AISI D2 steel, with 35 and 50 HRC. The microhardness and microstructure of the adhered material were determined, as well as the tool wear based on volumetric wear parameters. The layer adhered on the PCBN tool rake face has the same chemical elements as the machined steel alloy. Its microstructure is oriented in the direction of the chip flow and the primary carbides were fragmented. For the sample with 35 HRC the amount of material adhered (W_AM) on the rake face of the PCBN tool was approximately 360% higher than the steel with 50 HRC. The material layer adhered on the PCBN tool rake surface in the case of the 35 HRC steel acts as an edge (assuming the cutting function), while for the 50 HRC steel, the adhered layer intensifies the adhesion wear mechanism through spalling on the tool rake face. The results obtained provide important information for the selection of materials and grades for the development of new cutting tools.