金刚石刀具几何参数对已加工表面残余应力的影响

针对微米级切削深度的超精密车削中金刚石刀具几何参数对已加工表面残余应力的影响,采用有限元的方法,建立超精密车削的有限元仿真模型,对硬铝合金的超精密车削过程进行模拟。对车削过程的切削力和切削温度进行分析。采用不同的刀具几何参数进行有限元仿真,得到刀具前角、后角和钝圆半径对已加工表面残余应力的影响和分布规律,为超精密车削中残余应力的控制提供仿真依据。     

AISI1045号淬硬钢车削加工过程中刀具磨损预测

刀具磨损是车削加工淬硬钢等硬质材料过程中一直存在的一个难题,因而对刀具磨损和刀具寿命的进行定量预测具有重要的意义。建立了车削加工过程刀具磨损预测模型,并对该模型进行仿真分析和实验验证。以前的相关研究在分析刀具磨损的大小和位置时,大都是基于磨粒磨损、缺陷扩散或黏着磨损等机理建立单一的数学模型,预测结果会有较大的偏差。为了克服此缺陷,综合考虑磨粒磨损、缺陷扩散及黏着磨损等三种刀具磨损机理的影响,采用了一种新的刀具磨损预测耦合模型。然后将建立的磨损模型导入到有限元分析软件Deform-3D中,并对车削淬硬钢的加工过程进行模拟,分析中刀具的磨损规律;最后选用CBN刀具车削AISI 1045号淬硬钢进行实验研究,验证和评估预测模型的可靠性。结果表明,实验与仿真分析的结果具有很好的一致性,预测模型是可靠和有价值的。     

三维车削加工的Deform-3D有限元模拟

本文在建立车削三维有限元模型基础上,运用有限元法对车削低碳钢过程中切屑的变形系数、工件与刀具的温度分布、切削力进行了模拟,并对结果进行了分析讨论。该模拟的结果对部队的实际工作有重要的现实作用。     

细长轴对称式双刀车削刀具间距的仿真研究

通过建立细长轴的对称式双刀车削受力模型,对双刀车削的刀具间距进行理论分析,得到刀具加工点位置与刀具间距的关系.用有限元法对细长轴双刀车削的刀具间距进行瞬态动力学仿真分析,得出刀具间距与细长轴的位置关系曲线,确定两刀具间距的最优解以及对称式双刀车削的走刀方式.     

预应力切削过程刀具磨损的离散元模拟与试验研究

采用颗粒离散元法建立了描述切削过程中陶瓷刀具与切屑摩擦磨损行为的离散元模型;基于预应力切削原理,设计了一种用于车削加工环类零件的预应力加载装置,采用Sialon陶瓷刀具对GH4169环类工件进行了预应力车削试验,结合离散元模拟分析了预应力切削条件下切削力和刀具磨损的变化规律。结果表明:随着预应力的增大,预应力对刀具的磨损形态和机理没有明显的影响,刀具磨损随预应力的增大逐渐减小,在一定范围内提高切削速度可减少刀具的磨损。离散元模拟结果与试验结果具有一致性,验证了应用离散元模拟陶瓷刀具磨损的可行性。     

NC车削加工仿真体系结构研究及实例设计

在Visual C 平台上利用OpenGL技术建立虚拟数控车削加工环境,用C 语言把NC代码转换为计算机易于处理的数据信息,并将切削过程中各个物理因素的变化映射到虚拟制造系统中,通过用SQL Server建立的多个数据库支持几何仿真的图形算法与物理仿真的数值计算,进行虚拟环境下数控车削加工的几何仿真及物理仿真.和以往的仿真系统相比,可以全面实现刀具尺寸磨损、刀具受热变形、加工误差、表面粗糙度的预测及冷却液和屑形的模拟.     

基于切削加工特征的车削刀具的选择

通过对车削加工特征进行分析和分类,结合对车削刀具结构的研究,确定基于切削加工特征的车削刀具选择原则和方法。建立基于切削加工特征的刀具选择车削数据库系统,实现车削刀具及其切削参数的智能选取。     

可转位硬质合金车刀车削45钢车削力预报

采用金属成形有限元分析软件Deform3D建立了可转位硬质合金车刀车削45钢的三维斜角切削有限元模型,利用该模型进行了切削加工模拟,得到切削力的数值并给出了切削力随时间的变化曲线.通过设置不同的切削参数,对不同参数下的车削力进行比较,分析各个切削参数对车削力的影响规律,为研究刀具的切削性能提供有用的数据.     

车削数据库的研究与建立

本文在对车削数据进行搜集和评价的基础上,建立了车削数据库系统并开发了应用程序。该系统可以指导用户选择合适的刀具材料,提供车削参数,对加工表面质量进行预测并分析刀具非正常损坏的原因。该系统的建立有助于刀具的合理运用和提高生产率。     

基于ABAQUS和灰色系统的硬脆材料可车削性评价

利用ABAQ US对硬质合金刀具车削硬脆材料进行了模拟,得到车削力与车削温度,并根据磨损率公式利用M ATLAB对刀具磨损量进行了计算。基于灰色定权聚类模型对11种硬脆材料的可车削性进行了评价,以刀具磨损量作为判断硬脆材料可车削性的依据,对灰色评价结果进行了检验,检验结果与灰色定权聚类的结果相一致,表明利用灰色定权聚类模型评价硬脆材料的可车削性具有一定的可靠性。     

PCBN刀具高速切削镍基高温合金切削力及刀具磨损试验研究

高速切削加工过程中切削参数的选择对刀具切削性能具有较大的影响。镍基高温合金因在高温条件下仍具有较高的抗疲劳强度、屈服强度、抗拉强度等特点,被广泛应用于航空航天、船舶、核电等行业。但是镍基高温合金的切削加工性能差,主要表现在切削力大、切削温度高、刀具磨损现象严重等方面。本文从切削速度、进给量、切削深度等切削参数对切削力的影响进行研究,同时对PCBN刀具磨损形貌进行分析。采用PCBN刀具进行高温合金车削试验,得到PCBN刀具切削高温合金GH4169时切削参数对切削力的影响规律,并探讨不同刀具磨损形貌产生的原因,为高温合金高速切削加工参数制定及工艺优化提供一定参考。     

Al2O3基陶瓷刀具车削300M超高强度钢的刀具寿命研究

采用对角正交回归试验法,求得Al2O3基陶瓷刀具切削300M超高强度钢的刀具寿命经验公式,并分析了切削用量对刀具寿命的影响.通过扫描电子显微镜的观察和能谱分析仪的分析,对Al2O3基陶瓷刀具的损坏形态和磨损机理进行了研究.研究表明:Al2O3基陶瓷刀具车削300M超高强度钢时,粘结磨损和磨粒磨损是主要的磨损机理;合理的切削参数为:切削速度200～300 m/min、切削深度0.1～0.15 mm、进给量0.05～0.1 mm/r.     

Al_2O_3刀具车削NbC/Fe粉末冶金复合材料时的磨损

通过对Al2O3/(W,Ti)C陶瓷刀片车削NbC铁基粉末冶金复合材料的试验研究,探讨了刀具的主要磨损形式,分析了复合材料中增强相含量和材料密度以及切削参数等因素对刀具磨损的影响。结果表明:陶瓷刀具不会发生严重的磨粒磨损,刀具的高脆性及硬质颗粒的剧烈刮擦、冲撞引起的切削刃微崩和剥落磨损是刀具磨损的主要原因;工件材料增强相含量越高,对刀具的磨损越大;在相对密度大于90.3%的范围内,材料密度对刀具磨损的影响不太显著,当密度进一步降低时,刀具磨损率迅速下降;切削速度越高、背吃刀量越大、进给量越小,刀具磨损越快;此外,切削速度对刀具磨损的影响最显著,而进给量对刀具磨损的影响最小。     

Use of Ceramic Tools in Hard Turning of Hardened AISI M2 Steel

Tool wear and machining performance of hardened AISI M2 steel in hard turning has been studied. Ceramic tools were used in the cutting tests without coolants, and the workpiece was heat treated to increase its hardness up to Re 60. Cutting forces, temperature, and tool wear were measured in the experiments and the effects of cutting conditions on these were investigated. Important aspects from the research are summarized as follows: 1. Flank wear was the dominant wear mode on the ceramic tool insert in hard turning. In contrast, crater wear was very small due to the ceramics high resistance against chemical reactions at high temperature. A notch was unlikely to be formed in the tool.

2. The initial flank wear rate mainly depends on the feed rate. High feed rates cause a high initial flank wear rate.

3. Depth of cut was the most important cutting parameter to affect cutting force variation, and the cutting force increased due to tool wear.

     

高合金不锈钢的干车削和近干车削研究

高合金不锈钢具有强度高、韧性好、耐腐蚀等优良性能而得到日益广泛的应用,但是其难加工性同时也对切削技术提出了更高的要求.干切削因具有对环境和人体无害、经济性好等优点成为金属加工技术的主要发展方向之一.文中对高合金不锈钢Y12Cr17和16Cr17Ni3的干车削和近干车削中,切削参数和切削材料对刀具磨损和工件表面质量的影响进行了深入研究.结果表明,通过选择适当的切削参数、刀具材料以及刀具涂层,可以很好地实现高合金不锈钢的干车削加工,并能获得比传统乳化剂加工更小的磨损值和更好的工件表面质量.     

An empirical survey on the influence of machining parameters on tool wear in diamond turning of large single-crystal silicon optics

We conducted a series of screening experiments to survey the influence of machining parameters on tool wear during ductile regime diamond turning of large single-crystal silicon optics. The machining parameters under investigation were depth-of-cut, feed rate, surface cutting speed, tool radius, tool rake angle and side rake angle, and cutting fluid. Using an experimental design technique, we selected twenty-two screening experiments. For each experiment we measured tool wear by tracing the tool edge with an air bearing linear variable differential transformer before and after cutting and recording the amount of tool edge recession. Using statistical tools, we determined the significance of each cutting parameter within the parameter space investigated. We found that track length, chip size, tool rake angle and surface cutting speed significantly affect tool wear, while cutting fluid and side rake angle do not significantly affect tool wear within the ranges tested. The track length, or machining distance, is the single most influential characteristic that causes tool wear. For a fixed part area, a decrease in track length corresponds to an increase in feed rate. Less tool wear occurred on experiments with negative rake angle tools, larger chip sizes and higher surface velocities. The next step in this research is to perform more experiments in this region to develop a predictive model that can be used to select cutting parameters that minimize tool wear.     

Real-time monitoring of flank wear behavior of ceramic cutting tool in turning hardened steels

Flank wear of an alumina-based ceramic cutting tool was determined in hard turning two workpieces (AISI 4340 and 52100 hardened steels) at three cutting speeds (142, 181, and 264?m/min) to devise a real-time monitoring system. Results of the six turning tests were assessed using Kruskal?CWallis test, regression models, and linear trend analysis. Multiple non-linear regression models that explained variation in flank wear as a function of time (second) had a range of $ R_{\rm{adj}}^2 $ values of 27.7% for the test 4340-142 to 95% for the test 52100-181. Linear trend models revealed that the highest flank wear rate of the ceramic cutting tool belonged to the test 52100-181. Interaction effect of the three cutting speeds and the two workpiece types was determined to account for 82.2% of variation in flank wear (P?<?0.001). The real-time monitoring system designed in this study appeared to be promising in terms of determining and quantifying flank wear behavior of the ceramic cutting tool and optimal hard turning conditions.     

Measurement and optimization of surface roughness and tool wear via grey relational analysis,TOPSIS and RSA techniques

Magnesium alloy (Mg alloy) is one among the lightest materials and which has wide applications in the production of aircraft engines, airframes, helicopter components, light trucks, automotive parts and computers parts for its attractive properties. In this paper, a study to analyze the turning properties of magnesium alloy AZ91D in dry condition with polycrystalline diamond (PCD) cutting inserts is presented. Firstly, to investigate turning of magnesium alloy using grey relational analysis and TOPSIS of optimum cutting parameter values. Secondly, to determine using response surface analysis of mathematical model depending on cutting parameters of surface roughness and tool flank wear in turning. The adequacy of the developed mathematical model is proved by ANOVA. The findings from the investigation showed that feed rate and cutting speed are the dominant factors for surface roughness and tool flank wear respectively.     

高速车削钛合金时PCBN刀具寿命的研究

采用对角正交回归试验法,研究了用PCBN刀具高速车削钛合金TC4时切削用量对刀具寿命的影响,并分析工件已加工表面粗糙度。通过扫描电镜观察分析,证实刀具的磨损机理主要是前后刀面的粘结磨损及氧化磨损、后刀面磨损以及切削深度线处的沟槽磨损。     

Effect of tool edge wear on the cutting forces and vibrations in high-speed finish machining of Inconel 718: an experimental study and wavelet transform analysis

High-speed machining has been receiving growing attention and wide applications in modern manufacture. Extensive research has been conducted in the past on tool flank wear and crater wear in high-speed machining (such as milling, turning, and drilling). However, little study was performed on the tool edge wear??the wear of a tool cutting edge before it is fully worn away??that can result in early tool failure and deteriorated machined surface quality. The present study aims to fill this important research gap by investigating the effect of tool edge wear on the cutting forces and vibrations in 3D high-speed finish turning of nickel-based superalloy Inconel 718. A carefully designed set of turning experiments were performed with tool inserts that have different tool edge radii ranging from 2 to 62???m. The experimental results reveal that the tool edge profile dynamically changes across each point on the tool cutting edge in 3D high-speed turning. Tool edge wear increases as the tool edge radius increases. As tool edge wear dynamically develops during the cutting process, all the three components of the cutting forces (i.e., the cutting force, the feed force, and the passive force) increase. The cutting vibrations that accompany with dynamic tool edge wear were analyzed using both the traditional fast Fourier transform (FFT) technique and the modern discrete wavelet transform technique. The results show that, compared to the FFT, the discrete wavelet transform is more effective and advantageous in revealing the variation of the cutting vibrations across a wide range of frequency bands. The discrete wavelet transform also reveals that the vibration amplitude increases as the tool edge wear increases. The average energy of wavelet coefficients calculated from the cutting vibration signals can be employed to evaluate tool edge wear in turning with tool inserts that have different tool edge radii.