Cutting edge geometries

Tool life and performance are decisively determined by cutting edge geometry. An appropriate shape of the cutting edge improves wear resistance, tool life and process reliability. This paper reviews major developments in cutting edge preparation technologies and methods of cutting edge characterization. Moreover, the influences of cutting edge geometry on chip formation, material flow, as well as mechanical and thermal loads on the tool are discussed. The essential modeling and simulation approaches are presented. Effects on surface integrity are described. Finally, an overview of important perceptions for prospective research and development in this field is provided.     

Chatter Stability of Metal Cutting and Grinding

This paper reviews fundamental modeling of chatter vibrations in metal cutting and grinding processes. The avoidance of chatter vibrations in industry is also presented. The fundamentals of orthogonal chatter stability law and lobes are reviewed for single point machining operations where the process is one dimensional and time invariant. The application of orthogonal stability to turning and boring operations is presented while discussing the process nonlinearities that make the solution difficult in frequency domain. Modeling of drilling vibrations is discussed. The dynamic modeling and chatter stability of milling is presented. Various stability models are compared against experimentally validated time domain simulation model results. The dynamic time domain model of transverse and plunge grinding operations is presented with experimental results. Off-line and real-time chatter suppression techniques are summarized along with their practical applications and limitations in industry. The paper presents a series of research topics, which have yet to be studied for effective use of chatter prediction and suppression techniques in industry.     

高压水射流切割技术及其应用

高压水射流切割是一种非传统的冷切割方法,具有传统切割方式难以比拟的优点。本文回顾了其原理和发展历史,介绍了其在工业、航天和医学等方面的应用。对水压、流速、射流直径、直径扩散率以及磨料等切割参数对高压水射流切割的加工质量的影响进行了讨论,并对国外新的研究方法和结果进行了介绍,为优化工艺、改善加工质量提供了借鉴。     

基于切削力的铣削加工误差数学模型

针对铣削加工过程中由于工件、设备系统弹性变形以及刀具磨损导致的加工误差进行了分析和研究.提出了以切削分力作为主要参数的由于刀具磨损和工件与机械系统的弹性变形所带来的加工误差的数学模型.     

Grinding wheels for manufacturing of silicon wafers: A literature review

Grinding is an important process for manufacturing of silicon wafers. The demand for silicon wafers with better quality and lower price presents tremendous challenges for the grinding wheels used in the silicon wafer industry. The stringent requirements for these grinding wheels include low damage on ground surfaces, self-dressing ability, consistent performance, long wheel lives, and low prices. This paper presents a literature review on grinding wheels for manufacturing of silicon wafers. It discusses recent development in abrasives, bond materials, porosity formation, and geometry design of the grinding wheels to meet the stringent requirements.     

刀具状态监测与加工过程的适应性控制

概述了关于刀具状态监测与加工过程适应性控制的基本原理与方法，分析回答了该技术在应用与发展中的一些关键问题。     

数控超高压水射流切割技术的特点及其应用

超高压水射流技术是符合绿色制造概念的一种新型技术,是集泵、阀、密封、液压、自动化控制为一体的综合性新技术、新工艺.超高压水射流切割是一种非传统的冷切割方法,具有传统的切割方式难以比拟的优点.本文论述了数控超高压水射流切割机的基本工作原理、水射流切割的加工形式和水射流切割机床的组成,阐述了数控超高压水射流切割机的加工特点及其应用领域,并对超高压水射流切割技术发展趋势进行了展望.     

Performance Testing of Cryogenic CO2 as Cutting Fluid in Parting/Grooving and Threading Austenitic Stainless Steel

Experimental investigations were carried out in which the efficiency of cryogenic CO₂ was compared to that of a commercial water based product with respect to tool life, cutting forces, chip disposal and workpiece surface finish. The experimental results show that CO₂ applied at a rate of about 6 g/s is an efficient coolant for threading as well as for parting/grooving stainless steel. Threading can be carried out with gas alone but the best performance was obtained adding 6 ml/min unadditivated vegetable oil to the gas. In the case of parting/grooving, addition of oil (10 ml/min) to the gas is mandatory.     

On the Effects of Residual Stresses Induced by Coated and Uncoated Cutting Tools with Finite Edge Radii in Turning Operations

This paper presents an analysis of residual stresses in turning of AISI 316L and AISI 1045 steels with coated and uncoated tools having finite edge radii. An analytical predictive model, and experimental techniques involving X-ray diffraction and IR thermal imaging were used. Machining with coated tools produce higher superficial residual stresses, larger tensile layer thickness and higher residual stresses below the machined surface when using large cutting edge radii at low feed rates. This effect is correlated with the increase in the amount of heat conducted into the workpiece, and the associated generation of high tensile residual stresses and severe work-hardening.     

Hard AlTiN, AlCrN PVD coatings for machining of austenitic stainless steel

The austenitic stainless steels in general are considered to be difficult to machine materials. This is mainly due to the high plasticity and tendency to work-harden of the austenitic stainless steel, which usually results in severe cutting conditions. Additionally, austenitic stainless steels have much lower thermal conductivity as compared to structural carbon steels; this inflicts high thermal impact within the chip-tool contact zone, which significantly increase the cutting tool wear rate. The machineability of austenitic stainless steels can be improved due to application of coated cutting tools. Hard PVD coating with low thermal conductivity and improved surface finish should be used in this case. This can result in enhancement of frictional characteristics at the tool/workpiece interface as well as chip evacuation process. In this study the stainless steel plates were machined using cemented carbide finishing end mills with four high aluminum containing PVD coatings namely: AlCrN, AlCrNbN, fine grained (fg) AlTiN and nano-crystalline (nc) AlTiN. Both AlTiN and AlCrN-based coatings have high oxidation resistances due to formation of aluminum oxide surface layers. The influence of surface post-deposition treatment on tool wear intensity was investigated. The coating surface texture before and after post-deposition treatment was analyzed by means of the Abbot-Firestone ratio curves. Minimal wear intensity after length of cut 150 m was achieved for cutting tools with the nc-AlTiN coating.     

切削用量对切削力和切削振动的影响

为探究车削时切削用量对切削力和切削振动的影响,设定半精加工的切削用量范围,采用正交试验设计方法制定试验流程,在数控机床上使用硬质合金外圆车刀对45#圆钢进行切削试验,切削过程不加冷却液,并分别使用Kistler切削力测量系统和Vib Pilot M+P切削振动测量系统同时采集3个方向的切削力信号和切削振动信号,对试验数据使用方差分析(ANOVA)、贡献率计算和相关分析的方法进行处理。结果表明:背吃刀量对主切削力和进给力的影响最大,进给量对背向力和3个方向切削振动的影响最大,而切削速度对各方向切削力和切削振动的影响都最小;切削力信号的误差要远小于切削振动信号的误差。试验分析结果可以为合理设计切削用量参数,有效选择切削状态监控信号提供参考。     

基于拟水平正交实验法的磨料水射流切割性能研究

磨料水射流切割作为一种新型的冷切割技术,凭借较强的切割能力和良好的切割质量,越来越多的应用到工程领域中。为了探究不同切割参数对磨料水射流切割性能的影响,采用拟水平法设计实验方案,进行钢板切割实验。实验结果表明:射流的切割能力与泵压和切割转速成正相关,喷嘴直径和切割靶距存在一个最佳范围,堆积作用和淹没状态都对切割性能有不同程度的影响。     

便携式磨料水射流系统切割X60钢的试验研究

磨料水射流切割技术能够满足油气储运设备设施应急抢修切割的需求。通过切割试验研究了便携式磨料水射流切割系统对管线钢的切割特性,得到压力、靶距和横移速度对切割深度的影响关系,提出了切割深度预测模型。结果表明:切割深度与切割压力成正比,与靶距和横移速度成反比。切割深度模型对切割结果预测的最大误差为15.04%,最小误差为0.87%,平均误差为5.98%,表明切割深度模型在一定参数范围内能够有效指导切割工艺的制定。     

智能型光学玻璃切割机切割实验及切割参数优化研究

通过控制变量的切割实验,提出根据相关经验及单因素变量法进行光学玻璃切割实验的方法。根据不同进刀位置的切割及不同切割摆动速度切割实验,进行数据分析得出智能型光学玻璃切割机切割较厚条状光学玻璃的最佳切割参数。该切割实验方法可为光学玻璃切割工程应用提供一定参考。     

预置表面织构对硬态切削加工的影响分析

利用电火花穿孔技术预置表面织构,有效抑制硬态切削过程中较大切削力的产生,避免刀具磨损加剧,提高刀具使用寿命。使用CBN刀具硬态切削GCr15淬硬钢,设计关于切削深度、切削速度、进给量三因素无织构正交切削仿真模拟及试验,利用极差、方差及信噪比值法对仿真及试验数据进行分析,确定最佳切削参数组合,以及各参数对硬态切削过程中产生的切削力的影响程度。使用最佳切削参数组合,硬态切削预置表面织构的GCr15淬硬钢,观测刀具磨损情况,测量切削力,并与无织构等同切削条件下的结果进行对比分析,验证预置表面织构能够有效降低刀具磨损,提高刀具使用寿命。     

阳极切割机的研制

分析了是极切割机的原理，并介绍了该设备的构造以及切割电流、切割盘线速度对切割速度的影响，指出这种设备构造简单，切割生产率高，在切割某些合金铸件时比其它方法具有更大的优越性。     

磨削工艺对硬质合金切槽刀片刃口质量的影响

本文采用树脂结合剂金刚石砂轮磨削硬质合金切槽刀片的断屑槽和周边,形成刀片的切削刃口。采用D46和D64两种不同粒度的砂轮分别制备了5°、10°、15°前角的切槽刀片。在断屑槽的磨削过程中,采用了一次磨削和两次磨削两种方式。通过表面粗糙度仪测量了断屑槽和周边的粗糙度值,通过SEM测量了刀片的刃口缺陷。结果表明:砂轮粒度磨削周边对表面粗糙度的影响不大,断屑槽磨削的表面粗糙度受粒度影响较大;刀片前角越大,刃口完整性保持越差;相同条件下断屑槽采用两次磨削能获得更好的刃口质量。通过此试验,明确了生产现场磨削此类刀片的磨削工艺:磨削周边选用D64砂轮以提高加工效率,磨削断屑槽选用D46砂轮两刀磨削以提高表面质量,最终在兼顾磨削效率和质量的条件下可获得较好的刃口质量。     

切削用量对车削42CrMo钢切削力的影响

在单因素条件下通过改变切削用量车削42CrMo钢试验,得出了切削用量的改变对主切削力、进给力、背向力与总切削力的影响规律,分析了切削用量的改变导致切削力变化的原因,提供了车削42CrMo钢半精加工阶段的参考切削用量。结果表明:背吃刀量和进给量的改变对主切削力的影响较大,而切削速度的改变对主切削力影响较小;总切削力的变化规律与主切削力相似,背吃刀量对进给力的影响较大。     

切削参数对碳钢微量润滑切削温度的影响

为了了解切削参数影响碳钢微量润滑切削温度的规律,通过45钢的车削实验,利用自然热电偶测温,探明在干切削、传统浇注润滑和微量润滑条件下,不同切削参数对切削温度的影响及原因。实验结果表明:MQL切削温度随切削参数增大而上升,切削速度对MQL温度影响最大,切削深度影响最小;在低切削速度时,MQL冷却效果优于传统浇注润滑,在中、高速时,MQL冷却效果比浇注润滑差;MQL冷却能力随切削速度和进给量增大而减弱,不随切削深度而变化。     

MQL与普通切削液加工方法的实验研究

随着环境保护意识的提高，从降低加工成本和提高加工精度的需求出发，Minimal Quantity Lubrication(MQL)加工方法正被逐渐地研究与采用。通过实验并与普通切削油加工方法比较，MQL方法表现出其在刀具磨耗、切削阻抗、工件表面粗糙度影响方面比后者具有更优的物理与加工特性。