Mechanics of high speed cutting with curvilinear edge tools

High speed cutting is advantageous due to the reduced forces and power, increased energy savings, and overall improved productivity for discrete-part metal manufacturing. However, tool edge geometry and combined cutting conditions highly affects the performance of high speed cutting. In this study, mechanics of cutting with curvilinear (round and oval-like) edge preparation tools in the presence of dead metal zone has been presented to investigate the effects of edge geometry and cutting conditions on the friction and resultant tool temperatures. An analytical slip-line field model is utilized to study the cutting mechanics and friction at the tool-chip and tool–workpiece interfaces in the presence of the dead metal zone in machining with negative rake curvilinear PCBN tools. Inserts with six different edge designs, including a chamfered edge, are tested with a set of orthogonal cutting experiments on AISI 4340 steel. Friction conditions in each different edge design are identified by utilizing the forces and chip geometries measured. Finite-element simulations are conducted using the friction conditions identified and process predictions are compared with experiments. Analyses of temperature, strain, and stress fields are utilized in understanding the mechanics of machining with curvilinear tools.     

模具高速切削刀具技术研究概况

系统地介绍了模具高速切削刀具技术在各个领域的发展现状，包括：刀具材料、刀具磨损、刀具动平衡、刀具与机床的连接、刀具的可靠性、刀具的监测技术和刀具的几何参数。指出发展模具高速切削刀具技术，要从以下几个方面展开工作：研制和开发新的刀具材料，同时进行PCBN刀具切削性能的研究，推广其应用范围；进行模具高速切削刀具磨损机理的研究，进一步提高刀具寿命；做好刀具的动平衡，防止刀具的破损，保证工作人员的安全；进一步加强刀具监测技术的研究，以获得良好的加工质量；建立模具高速切削数据库，以便有效地利用刀具，提高刀具的寿命；大力推进有限元模拟技术在高速切削刀具技术中的应用。     

PCBN刀具高速切削淬硬轴承钢的磨损机理研究

采用美国D.I.公司生产的BZN9000作为刀具材料制成PCBN刀具,在沈阳机床厂生产的CA6140A车床上对GCr15淬硬轴承钢进行高速切削试验。对切削试验后刀具的前、后刀面进行SEM形貌观察和EDS能谱分析,结果表明:PCBN刀具在高速切削过程中,机械磨损、黏着扩散磨损和化学磨损是刀具磨损的主要形式;前刀面磨损主要为月牙洼磨损,切削刃处、月牙洼后、前刀面处的黏着元素扩散比月牙洼底部还要严重;对后刀面的WDS线能谱分析证实,切削刃处的黏着元素扩散比后刀面要严重。      

国内外高速钢刀具盐浴热处理工艺

高速钢问世至今已有110多年历史,尽管新的刀具材料不断涌现,但始终未能动摇其霸主地位。高速钢刀具热处理工艺主要有盐浴热处理和真空热处理两种,大型复杂刀具、细长刀具、接柄刀具等特殊刀具真空淬火尚有一定难度,盐浴处理仍是目前适用的工艺     

高速切削加工中的刀具技术

高速切削加工切削速度、进给速度和加速度提高近一个数量级,对刀具技术提出新的要求并促进其不断发展.文章分析了由于旋转离心惯性力大幅度增大引起的刀具与夹紧装置机械故障及其预防保护措施,概括了高速切削常用的刀具材料、应用范围及制造新技术,归纳了加工中缓解刀具寿命下降的工艺措施,介绍了新型的激光刀具检测系统的性能、工作原理和优点,表明刀具技术的综合性、系统性.     

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...     

变频调速系统在金属切削机床上的应用

变频调速是一种高性能的调速方法,就调速指标而言,其完全能够满足金属切削过程的基本要求。论文结合车床加工的基本特点,分析了变频调速系统的基本设计方法和基本设计过程,并介绍了相关元器件的选择及参数的调整原则。     

Cutting performance and wear mechanisms of Sialon ceramic cutting tools at high speed dry turning of gray cast iron

In the present work, the phase composition and microstructure of two Sialon cutting inserts (named sample A and sample B) were characterized by XRD and SEM. The cutting performance and wear mechanism of the cutting inserts were investigated at high-speed dry turning of gray cast iron. The results showed that the main phases of them were α- and β-Sialon, and the sample A contained more α-Sialon than that of sample B. The grains of the Sialon cutting inserts are mainly elongated shape, and the aspect ratios are about 5.32 and 5.09, respectively. The tool life of sample B was longer than that of sample A at low speed. However, with the speeds increased, the tool life of sample A was getting closer to that of sample B and then exceeded that of sample B. The wear mechanisms of the two cutting inserts were abrasive and adhesive wear, however, as the cutting speeds increased, the dominant wear mechanisms were different.     

Effect of ultrafine gradient cemented carbides substrate on the performance of coating tools for titanium alloy high speed cutting

Gradient cemented carbides usually used as substrate for coating tools, and the substrate has different gradient layer thickness and grain size, which would affect the cutting performance of the coating tools. In this study, different contents of Co and cubic carbonitride were added, the ultrafine gradient cemented carbides with different gradient layer thickness and grain size were prepared by one-step sintering, and then the CAT films (films containing Cr, Al and Ti, basically.) were deposited on alloy surface by Arc Ion Plating (AIP) in Ar gas atmosphere for titanium alloy high-speed cutting. The influence of Co and cubic carbonitride content on the microstructure of alloy and the cutting performance of coated tools was studied. The results show that the gradient layer thickness could be controlled by changing the Co and cubic carbonitride contents, and then affected the cutting performance. The coating tools enhanced cutting performance obviously by reducing the flank wear in the high-speed Ti-alloy cutting. A thinner gradient layer can be formed in alloys that with a lower Co addition, thus leading to tools chipping during high-speed cutting Ti-alloy. The wear resistance and the cutting performance of the tools could be improved by adding cubic carbonitride. The Co10Ti3-CAT coated tool has the best cutting performance. And the wear resistance of Co8Ti4-CAT coated tool can be increased by 50% compared to substrate.     

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.     

Ti（C, N）基金属陶瓷刀具的高速切削性能与磨损机理

使用不同C与N摩尔比的Ti（C, N）固溶体粉末作为基体材料,采用真空烧结工艺研制两种Ti（C, N）基金属陶瓷刀片试样,并考察两种刀片试样和日本住友T1200A在不同的切削速度下干式车削20CrMn工件的切削性能。利用扫描电子显微镜分析刀具前、后刀面的磨损形态和显微结构,阐述Ti（C, N）基金属陶瓷刀具高速切削磨损机理。结果表明：高速切削时Ti（C, N）基金属陶瓷刀具的主要磨损形式是粘结、氧化和扩散磨损;减小Ti（C, N）固溶体中C与N的比值可改善Ti（C, N）基金属陶瓷刀具的耐磨性。     

高速切削在叶片模具制造中的应用

叶片锻造模具因为叶片形状复杂,变截面、变弦长、有扭角,且叶片材料一般为材质优、价格昂贵难变形的材料,锻造时模具在分模面处容易出现塌陷,常需修整模具。通过对高速切削加工模具与传统工艺加工模具比较得出高速切削具有以下优点:提高加工效率,取代电火花加工,取代钳工钳修,提高了模具的使用寿命,以及只需降低模具的分型面,就可以修整模具。     

Critical cutting speed for onset of serrated chip flow in high speed machining

The transition of continuously smooth chip flow to periodically serrated chip flow as the cutting speed increasing is one of the most fundamental and challenging problems in high speed machining. Here, an explicit expression of the critical cutting speed for the onset of serrated chip flow, which is given in terms of material properties, uncut chip thickness and tool rake angle, is achieved based on dimensional analysis and numerical simulations. It could give reasonable predictions of the critical cutting speeds at which chips change from continuous to serrated for various metallic materials over wide ranges of uncut chip thickness and tool rake angle. More interestingly, it is found that, as the turbulent flow is controlled by the Reynolds number, the transition of the serrated chip flow mode is dominated by a Reynolds thermal number. Furthermore, the influences of material properties on the emergence of serrated chip flow are systematically investigated, the trends of which show good agreement with Recht’s classical model.     

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.     

高速钢刀具淬火畸变校直技术

<正>从微观视野分析,凡经过淬火之工件,都会产生或多或少的畸变,如果畸变大就必须经过校直,并认真查找原因,以致以后少畸变或微畸变,节能增效,为企业作出应有的贡献。1刀具在热处理过程中产生畸变的原因刀具热处理时发生体积变化(增大或缩小)、直线尺寸变化(伸长或缩短)和几何形状变化(弯曲、扭曲、椭圆、喇叭孔等)统称畸变。影响热处理畸变的因素较为复杂,以下列举比较重要的几个:1)钢材质量的影响钢材化学成分分布的均匀     

陶瓷刀具在干切削加工中的应用

文章论述了陶瓷刀具的特点和切削性能,对陶瓷刀具在干切削中的使用进行了分析.     

高速机床进给系统的发展趋势

在明确了高速加工对机床进给进给系统要求的基础上，比较和分析了滚珠丝杠、直线电机和并联虚拟轴机构等三种高速进给系统的性能、特点、存在问题及其解决办法，指出了它们各自的适用范围和应用前景。