氧化铝陶瓷刀具的发展和应用

介绍了氧化铝陶瓷刀具的种类和发展现状,阐述了氧化铝陶瓷刀具的切削性能及应用,提出了陶瓷刀具使用中的注意事项,并指出陶瓷刀具的应用范围.     

提高陶瓷刀具在干切削加工中性能的方法

陶瓷刀具具有优良的切削性能.本文论述了陶瓷刀具的特点和切削性能,提出了提高陶瓷刀具性能的几种途径,对陶瓷刀具在干切削中的应用进行了分析.     

提高纳米复合陶瓷刀具材料力学性能的方法

纳米复相陶瓷刀具材料的研究成功有望从根本上解决陶瓷材料的脆性问题,比起传统刀具陶瓷刀具材料,它具有更高的抗弯强度、断裂韧度等力学性能.介绍了纳米复相陶瓷的增韧补强机理;对研制高性能纳米陶瓷刀具材料需考虑的主要因素进行了探讨.     

Si_3N_4基复合陶瓷刀具切削温度场及热应力的有限元分析

应用有限元法对Si3N4基复合陶瓷刀具温度场和热应力进行了分析计算。通过建立Si3N4基复合陶瓷刀具三维温度场和热应力的有限元模型,确定边界条件,分析求解得到Si3N4复合陶瓷刀具的温度场和热应力。结果表明:普通单质陶瓷刀具随着切削速度的提高,其由切削温度引起的最大热Mises应力、最大热切应力以及最大热拉应力的增长幅度大于Si3N4基复合陶瓷刀具。说明Si3N4基复合陶瓷刀具由热应力引起的破坏比单质陶瓷刀具小,寿命长,更适合于高速切削。     

陶瓷刀具材料的研究进展

阐述了Al2O3系和Si3N4系陶瓷刀具材料的研究现状和应用情况,并对先进陶瓷刀具材料和涂层陶瓷刀具材料的研究现状进行了概述。分析了其研究思路,指出纳米改性、纳米复合、超细晶粒材料和优化组分、多相复合增韧补强是提高陶瓷刀具韧性的主要方法。     

陶瓷刀具的切削性能研究

对陶瓷刀具的性能、切削性能与硬质合金刀具进行了对比研究，阐述了陶瓷刀具的适用范围和使用过程中的注意事项。     

机械加工刀具的成分设计与切削性能研究

对比分析了陶瓷刀具和聚晶立方氮化硼刀具在不同切削加工参数下的硬态切削表面性能,并分析了刀具表面的磨损形貌特征。结果表明,陶瓷刀具和立方氮化硼刀具的表面粗糙度都随着切削速度和后刀面磨损程度的增加而降低;随着进给量的增加,陶瓷刀具和立方氮化硼刀具的表面粗糙度逐渐上升;切削深度对刀具表面粗糙度的影响不大。CBN刀具的磨损机制主要为磨粒磨损和氧化磨损。     

微喷砂时间对陶瓷刀具表面完整性影响研究北大核心

针对陶瓷刀具高速切削高温合金时刀具磨损严重的问题,采用微喷砂处理技术对Sialon基陶瓷刀具表面进行处理,研究喷砂时间对Sialon基陶瓷刀具表面完整性(微观形貌、表面粗糙度、维氏硬度、断裂韧度、残余压应力)的影响规律,提升陶瓷刀具表面完整性,从而提高刀具耐磨性。研究表明:在喷砂4 min、喷砂压强0.4 MPa的条件下,陶瓷表面微观缺陷得到改善,断裂韧度提升32%,残余压应力提升12%,可以获得综合水平较高的表面完整性,为陶瓷刀具微喷砂处理参数的选择提供理论性指导,有助于提升陶瓷刀具表面完整性。     

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.     

陶瓷刀具材料的研究现状

文章重点综述了纳米陶瓷、梯度复相陶瓷、氧化锆陶瓷等多相复合陶瓷刀具材料的研究现状,全面分析了陶瓷刀具材料的颗粒弥散增韧补强、纤维(或晶须)增韧、相变增韧及多种机理协同增韧等机制的研究动态.     

新型陶瓷刀具的发展与应用

回顾了陶瓷刀具的发展简况及其意义,重点介绍了Si3N4基和TiCN基复合陶瓷刀具的研制、性能和应用.复合Si3N4陶瓷刀具有较高的耐磨性和抗冲击性,特别适合于各类铸铁件的粗精加工,也能进行铣削、刨削等冲击力很大的加工,其切削效率可提高3～10倍;复合TiCN金属陶瓷刀具具有很高的硬度和耐磨性,特别适合于各类高硬高强钢(如淬硬钢等)的加工,可对高硬材料实现"以车代磨"干切削,免除退火工艺和冷却液,大幅度提高生产效率.新型复合陶瓷刀具已经在我国冶金、水泵、矿山机械、轴承、滚珠丝杠、汽车、军工等十几个行业得到应用.     

Machinability of hardened steel using alumina based ceramic cutting tools

Alumina based ceramic cutting tool is an attractive alternative for carbide tools in the machining of steel in its hardened condition. These ceramic cutting tools can machine with high cutting speed and produce good surface finish. The wear mechanism of these ceramic cutting tools should be properly understood for greater utilization. Two types of ceramic cutting tools namely Ti[C,N] mixed alumina ceramic cutting tool and zirconia toughened alumina ceramic cutting tool are used for our investigation. The machinability of hardened steel was evaluated by measurements of tool wear, cutting forces and surface finish of the work piece. These alumina based ceramic cutting tool materials produce good surface finish in the machining of hardened steel. In this paper an attempt is made to analyse the important wear mechanisms like abrasive wear, adhesive wear and diffusion wear of these ceramic cutting tool materials and the performance of these ceramic cutting tools related to the surface finish is also discussed here.     

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。     

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.     

超硬材料刀具的特性及应用

本文主要介绍了单品金刚石刀具，高温高压合成的聚品金刚石（PCD）刀具，聚晶立方氮化硼（PCBN）刀具及化学气相沉积的金刚石膜（CVD）刀具的特性及应用。我们做了有关CVD刀具与PCD刀具耐磨性的切削试验：通过试验可以看出，CVD刀具确实有较好的耐磨性，但是在切削时间为17min时，由于CVD较PCD脆，在25倍显微镜下观察发现CVD金刚石刀具的刀口有明显的崩刃。另外发现，CVD金刚石刀具在制造及使用过程中也极易出现崩刃现象，所以目前大多数厂家仍以使用PCD刀具为主，CVD金刚石刀具的推广仍需要一个过程。     

Fabrication techniques and cutting performance of micro-textured self-lubricating ceramic cutting tools by in-situ forming of Al2O3-TiC

In this study, different geometric micro-textured ceramic tools (MST-0, MST-1, MST-2) are designed using the software AdvantEdge (AE). The designed tools are used to perform FEM (finite element modelling) simulation of the cutting process. The simulation results show that, compared with the traditional non-texture tool (MST-0), applying the appropriate shape and size of micro-texture to ceramic cutting tools can significantly reduce the cutting force, decrease the cutting temperature and improve the cutting performance of the tool. Additionally, an experimental study was conducted that involved the fabrication of hot-pressing sintered micro-textured self-lubricating ceramic tools (MST-1, MST-2) by means of in-situ forming method. Furthermore, cutting tests to compare the cutting performance of the micro-textured self-lubricating ceramic tools with the traditional non-textured tool (MST-0) were performed. The results indicate that the in-situ formed micro-textured ceramic cutting tools can effectively reduce the cutting force, the cutting temperature, and the rake face wear. During the cutting process, the abrasive grain of graphite that is placed into the micro-texture by in-situ forming is squeezed into the microstructure. Thus, the graphite overflows from the microstructure under abrasive grains and covers the rake face. This helps to reduce the friction between the chip and the rake face, which further reduces the cutting force and temperature, and improves the cutting performance of the tools. The texture pattern orientation of the micro-texture also affects the cutting performance of the tool. It is found that the best cutting performance is obtained by the transverse micro-texture tool.     

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.     

铝合金高速铣削过程切屑成形机制研究

高速铣削加工中,切削力、切削热和机床振动等被广泛研究,而对切屑的研究相对较少.本文针对立铣刀高速铣削的特点,对切屑的成形进行了研究.根据理论分析,在UG环境下对切屑进行了绘制,其形状与实际切屑基本吻合,证明了研究方法的可靠性.通过切屑的研究反馈设计过程,对立铣刀的结构设计提供支持.     

Wear maps of Si3N4 ceramic cutting tool

Wear maps of a Si₃N₄ ceramic cutting tool for cutting 1045 plain carbon and 302 stainless steels are produced in this paper. Through the systematic turning tests, the optimum cutting regions were determined on the wear maps of a two-dimensional diagram of cutting speed and feed rate. They are important for selecting the appropriate cutting parameters for a ceramic tool when cutting different workpieces. The wear morphologies and wear mechanisms for the different regions were investigated by scanning electron microscopy (SEM) with energy dispersive analysis of x-ray (EDX), and the corresponding cutting temperature distributions were measured by a thermal video system. Based on the experiment results, the relationships between cutting conditions, cutting temperatures, and wear mechanisms were discussed in detail.