芳纶纤维复合材料切削加工缺陷研究

为研究芳纶纤维复合材料切削加工缺陷,改进加工效果,对各种加工缺陷进行了深人分析和研究,进行了一系列钻铣试验。提出了避免加工缺陷的工艺方法。试验表明,采用人字形螺旋刃进行铣削,对工件进行预夹紧和工艺涂覆进行铣削和钻削,可以有效避免分层、翻边、抽丝、拉毛等工艺缺陷,使用高强高韧和耐磨性好的刀具材料,控制切削工艺参数,可有效避免烧焦现象的产生。     

纤维增强复合材料钻削加工技术研究现状

纤维增强复合材料具有力学性能各向异性、导热能力差等特点,在钻削加工时,容易产生分层、撕裂等加工缺陷。综述了钻削轴向力、切削参数、刀具几何结构等对纤维增强复合材料钻削缺陷的影响,进一步分析了钻削加工技术的研究现状,提出合理的加工参数、刀具结构及新的钻削加工技术,对于提高钻削加工质量具有重要的意义。     

陶瓷刀具材料及应用技术

陶瓷刀具具有优良的切削性能，在金属切削加工中越来越受到重视。本文对陶瓷刀具的种类、性能和应用进行了论述，并指出陶瓷刀具材料的发展方向。     

超硬刀具现代切削加工中的重要手段

代表现代机械加工主流方向的高速切削加工,因顺应了21世纪机械加工高效率、高精度、柔性与绿色化的要求而迅速发展,这一技术主要应用于车削和铣削.高速干切削能消除切削液所带来的污染环境、危害工人健康的负面影响,是符合可持续发展要求的先进制造技术.精磨是轴承精加工中最常用的加工工艺,随着PCBN刀具的出现及数控机床等加工设备精度的提高,以硬态切削代替磨削来完成零件的最终加工已成为硬轴承钢的一个新的精加工途径.后继工序有超精加工或精度磨削要求时,硬态切削是最好的选择.要实现高速切削、干切削、硬态切削,精密和超精密切削,刀具材料是关键.而PCD、PCBN刀具为上述切削技术的实现提供了最基本的前提条件.     

具有微细表面形状的DLC涂层切削刀具的开发

改善刀具与切屑或工件之间的润滑性能对获得良好的切削性能是极其重要的.尤其是MQL加工要求达到很高的润滑性能.但是,MQL加工存在润滑性能差或稳定性不足等问题,在实际加工中的应用十分有限.为了弄清这一问题,对铝合金在供应切削油的情况下进行断续切削-断面铣削试验.结果证实,刀具和切屑间的润滑性能随着切削的进行,即随着切削长度的延长而下降.为了解决这一问题,开发出具有微细表面形状(即微槽)的刀具,以期微槽能起切削液保持环的作用.一系列切削试验表明,与无微槽的常规刀具相比,新开发刀具的剪切角增大,切削力减小.这证明,微槽能降低刀具表面的摩擦.另外还发现,新开发刀具在MQL加工中能有效地保持良好的润滑性能.     

芳纶纸蜂窝复合材料车削工艺性研究

芳纶纸蜂窝复合材料的车削加工中,易出现结构破损及表观质量差等质量问题。研究从分析芳纶纸蜂窝材料车削加工工艺特性入手,讨论影响芳纶纸加工的关键因素,据此进行刀具选材及几何角度优化设计,设定合适的转速、进给量等车削工艺参数,提出了若干适合实际操作的工艺技巧,最大限度保证刀具刃部有效切断芳纶纸纤维,避免各种加工质量问题。     

ZrO2/CePO4可加工陶瓷材料钻削加工的试验研究

分别用高速钢刀具和硬质合金刀具对ZrO2/CePO4可加工陶瓷材料进行钻削加工试验.通过比较ZrO2/CePO4陶瓷和低碳钢材料的加工过程,分析了ZrO2/CePO4陶瓷的加工特性、材料钻削规律及其影响因素.实验结果表明:刀具的磨损是ZrO2/CePO4钻削加工的主要特征之一.钻削ZrO2/CePO4陶瓷材料的去除过程可分为高效率和高磨损2个阶段,刀具材料影响ZrO2/CepO4可加工陶瓷材料的加工效率.可加工陶瓷的加工过程中,应选择合理的刀具参数和加工工艺参数,以获得良好的加工质量.     

碳纤维复合材料高速钻削力的研究

在钻削碳纤维复合材料时，经常会遇到分层、劈裂等各类加工缺陷，而这些缺陷主要是由钻削轴向力引起的。本文就高速钻削条件下刀具、转速、进给量、钻孔个数、材料厚度等钻削参数对轴向力的影响进行了全面系统的研究。     

SiC_p/Al复合材料的切削加工性能研究

通过PCD、PVD、CBN和YG6X四种不同材质的刀具对高体积分数的Si Cp/Al复合材料进行切削加工,分别从表面形貌、表面粗糙度以及表面残余应力三方面来综合表征复合材料加工后的表面质量,得出PCD刀具是切削加工高体积分数Si Cp/Al复合材料的最佳刀具。     

电镀金刚石刀具的制备及其钻削性能研究

采用复合电镀方法制备金刚石刀具。阐述了刀具的制备过程,并通过钻削实验对比了普通高速钢刀具与电镀金刚石刀具的钻削性能。结果表明:钻削颗粒增强金属基复合材料时,电镀金刚石刀具的加工质量和耐用度均优于普通高速钢刀具的。     

Effects of tool coating materials and coating thickness on cutting temperature distribution with coated tools

Coated tools are currently widely used tool technology in machining. The influence of tool coating on heat transfer has become an active field of research enjoying constantly increasing attention in the field of machining. This paper is devoted to the cutting temperature in machining H13 hardened steel with monolayer coated tools (TiN, TiAlN, and Al₂O₃) and multilayer coated tools (TiN/TiC/TiN and TiAlN/TiN). Equivalent composite thermal conductivity and thermal diffusivity of multilayer coated tools were calculated using the equivalent approach. The established heat transfer analytical models estimated coating temperature in turning. The effect of tool coating in steady and transient heat transfer was studied, as well as the cutting temperature distribution. It reveals that the tool coating material and coating thickness can influence the cutting temperature distribution of coated tool. Thermal conductivity of coating material affects the steady cutting temperature distribution, and thermal diffusivity of coating material affects the transient cutting temperature distribution of coating tools.     

Performance and wear mechanism of spark plasma sintered WC-Based ultrafine cemented carbides tools in dry turning of Ti–6Al–4V

Cutting performance and failure mechanisms of spark plasma sintered (SPS) ultrafine cemented carbides in dry turning Ti–6Al–4V were studied. The tools of UYG8 (WC-8wt%Co) and UYG8V2B10 (WC-8wt%Co-0.2 wt%VC-1.0 wt%cBN) exhibited higher lifetime and better processing quality than the commercial YG8 cemented carbide tool. The cutting distance of UYG-8 and UYG8V2B10 tools are 1.8 and 1.6 times longer than that of YG8, respectively. Cutting-edge breakage was found as the main failure forms of the SPS cemented carbide tools containing low Co content (≤6 wt%), whereas the SPS cemented carbide tools containing high Co content (≥8 wt%) exhibited flank and rake wear as main failure forms caused by abrasion, adhesion, diffusion, and oxidation. UYG8V2B10 tool wear mechanism was affected by cutting speed and depth. Wear mechanisms of UYG8V2B10 tool are mainly adhesive wear and oxidative wear at low cutting speed, but follow adhesive wear and diffusive wear at higher cutting speed. Moreover, with increasing cutting depth, tool failure forms are mainly breakage and chipping, largely induced by high cutting temperature and severe cutting vibration.     

Experimental investigation of different morphology textured ceramic tools by in-situ formed for the dry cutting

Surface texture is considered an important measure to improve the cutting performance of a tool. In this study, we have prepared three types of textured and conventional tools on the rake face by an in-situ formed method. During the experiment, the best parameters of three types of textured tools were selected for dry cutting AISI 1045 steel at different cutting speeds. Cutting forces, cutting temperatures, workpiece surface roughness, and tool wear were measured during the cutting process. The results showed that textured tools have significantly reduced cutting force, cutting temperature, and tool wear, and the roughness of the workpiece was improved compared with the conventional tool. The micro-pit texture tool has less stress contact region than the micro-groove width texture tool, but the micro-groove width texture tool exhibiting the best cutting performance. This investigation clearly showed that the textured tool prepared by the in-situ formed method has improved cutting performance.     

Applicability of DLC and WC/C low friction coatings on Al2O3/TiCN mixed ceramic cutting tools for dry machining of hardened 52100 steel

The present work examines the applicability of DLC and WC/C low friction coatings on Al₂O₃/TiCN based mixed ceramic cutting tools for the dry and hard turning of AISI 52100 steel (62 HRC). The characterization of coated tools reveals that the coatings retain very low values of surface roughness, whereas the DLC coating exhibits much higher microhardness when compared to the WC/C coating. On the other hand, the WC/C coating exhibit a coarse surface morphology virtually due to the tungsten doping. Later, continuous turning tests were executed with the help of coated and uncoated cutting tools under dry cutting conditions, and their performance was investigated in terms of machining forces, cutting temperature and tool wear. Coating delamination by flaking and peeling is quite prominent in the case of both the coatings; however, it is less severe for the WC/C coated tool. The coatings help to reduce machining forces, cutting temperatures and tool wear, but the performance of coated tools converge towards uncoated tool as the cutting speed, and feed rate is increased. Both the coatings prevent the development of cracks near the cutting edge with WC/C coating exhibiting superior wear behavior basically due to its multilayered structure and better thermal stability. Moreover, the tested low friction coatings don't serve as thermal barriers and only the lubrication generated due to graphitization at the chip-tool interface is mostly responsible for the improved machining performance.     

粉末涂层陶瓷材料的切削性能及磨损机理

对粉末涂层陶瓷材料FTC1和FTC2的切兴旺性能进行了实验,并对其磨损机理进行了探讨。实验证明FTC1和FTC2完全可以作为刀具材料使用,并且在中低速度下切削调质45号钢和淬硬T10A工具钢时,FTC1和FTC2具有比YB01更好的切削性能。在切削淬硬T10A工具钢时,YB01的后刀面有明显的塑性磨损特征,而FTC1的后刀面的磨损主要是磨粒磨损和粘结磨损,FTC2的后刀面挤压磨损特征较明显。     

技术创新助推新型陶瓷刀具在机加工中的应用优势凸显

随着新技术革命的发展,要求不断提高切削加工生产率和降低生产成本,特别是数控机床的发展,要求开发比硬质合金刀具切速更高、更耐磨的新型刀具。针对新型陶瓷切削刀具的应用前景广阔,分析了切削刀具材料的种类及其特点,研究了新型陶瓷切削刀具的性能突显,介绍了新型陶瓷切削刀具运用实例,提出了陶瓷切削刀具材料的研发应用方向。     

Si3N4陶瓷刀具在切削淬硬钢时的磨损行为

采用两种Ｓｉ２Ｎ４刀具在普通车床上对ＣｒＷＭｎ和４５钢进行切削试验，并用ＳＥＭ，ＥＤＡＸ，ＸＰＳ等方法对刀具的磨损进行分析。结果指出：试验的陶瓷刀具材料在切削不同淬硬钢时均存在最佳切削速度。在ＦＤ０１相比，ＦＤ０２陶瓷刀具有更佳的切削性能，最佳切削速度可提高７８％。在最佳速度以下切削，刀具侧面将发生粘着磨损；在最佳速度以上，则被加工材料产生微区熔化，导致材料大面积转移，发生剥层磨损，最佳速度以下切     

自润滑陶瓷刀具切削过程中的减摩机理研究

采用热压法CaF2作为添加剂,Al2O3/TiC(LT55)作为基体制备出了自润滑陶瓷刀具,并对其进行了干切削试验.在切削过程中,在刀具前刀面上能形成自润滑膜,从而使刀具具有减摩性能.用扫描电镜观察了前刀面和后刀面微观结构.LT55在切削加工45钢时,Al2O3/TiC/CaF2(ATF)自润滑陶瓷刀具前刀面的平均摩擦系数比未添加固体润滑剂的LT55陶瓷刀具显著降低,其主要原因是在ATF自润滑陶瓷刀具的前刀面上形成了一层固体润滑膜,这层润滑膜可起到减摩作用.自润滑刀具在切削过程中,自润滑膜经历生成、破损、脱落、再生成的循环过程,因此,ATF自润滑陶瓷刀具在其整个生命周期内都具有自润滑效果.自润滑刀具后刀面不存在固体润滑膜,具有较明显的磨料磨损特征.     

Reliability analysis of ceramic cutting tools in continuous and interrupted hard turning

Reliability analysis was carried out for ceramic cutting tools used in continuous and interrupted hard turning. On the basis of micromechanics and damage mechanics, statistical characteristics of the original defects in the tool material microstructure were evaluated and analyzed. A new tool performance indicator was proposed considering the combined effects of the original damage of the tool material microstructure, the macro-mechanical properties of the tool material and the external loads on the cutting tool. Statistical analysis of the tool performance indicator was performed for continuous and interrupted turning. The relationship between tool reliability and the probability distribution of tool performance indicator was identified. It was found that the original damage of the ceramic tool material followed a weibull distribution. The probability density of the original damage decreased as the original damage increased. When interrupted turning was adopted, tool performance indicator was relatively low and the indicator decreased as cutting length ratio became smaller. The indicator followed a weibull distribution and this was invariable when turning condition changed. Relatively low shape parameter and scale parameter in probability density function of tool performance indicator appeared when the tool was tested in interrupted turning and relatively small cutting length ratio was applied. Similar to tool performance indicator, tool lives obtained under different cutting conditions also followed a weibull distribution. When turning condition varied, shape parameter and scale parameter in probability density function of tool life changed in a similar way to those parameters in probability density function of tool performance indicator. Both the probability density function of tool life and that of tool performance indicator first increased and then decreased as the independent variable increased. Shape parameter for tool performance indicator can be used in the calculation of tool reliability when the cutting length ratio in interrupted turning was relatively small.     

Investigation of novel multiscale textures for the enhancement of the cutting performance of Al2O3/TiC ceramic cutting tools

Currently, the high temperature and severe friction conditions at the tool-chip interface are the main reasons for ceramic tool wear failures. Surface texturing as a geometric extension for cutting tools is a promising way to extend their service life. In this study, a novel type of multiscale texture was developed, and its effect on the cutting performance of an Al₂O₃/TiC ceramic cutting tool while machining AISI H13 steel was explored in a conventional cooling environment. The cutting force, cutting temperature, and tool wear morphology were investigated at cutting velocities ranging from 80 to 249 m/min. Microgroove textured Al₂O₃/TiC ceramic tools were prepared for comparison. The results show that the structure of the multiscale textures maintained good integrity over the range of cutting velocities. Thus, the synergistic effect of the microscale and nanoscale textures promoted the introduction and permeation of the cutting fluid. Therefore, the multiscale textures effectively enhanced the cutting performance of the Al₂O₃/TiC ceramic tools.