带减摩槽刀片切削机理的试验研究

本文通过对平前刀面和带减摩槽刀片的基本切削试验结果的分析 ,考察了减摩槽对主切削力 (Fz)以及切削变形和断屑性能的影响 ,在此基础上得出对三维断屑槽设计的一些有益结论 ,并据此设计了一种新型的断屑槽。     

硬质合金可转位车刀片UG型断屑槽断屑机理的研究

本文采用接触图形法对硬质合金可转位车刀片UG型断屑槽的断屑机理进行了实验研究．结果表明：由于采用了根据不同切削深度和进给量巧妙改变有效槽宽、使切屑横截面弯曲呈拱形、弹形挡屑筹措施，UG型断屑槽具有断屑范围较宽、在进给量较大时不易出现过分断屑等特点．此外，文中还对化学气相涂层刀片的UG型断屑槽在切削速度明显提高以后断屑范围的变化进行了研究．文中给出的UG型断屑槽的断屑范围图可供实际选用．     

论刀具磨损量与断屑槽断屑的关系

本文通过实验研究和理论分析,讨论了前、后刀面磨损量对断屑槽断屑效果的影响及断屑槽槽形与磨损量的关系,还讨论了改变槽形以减少磨损量、提高刀具寿命并达到最佳断屑效果的断屑槽的设计原则。图4幅。     

复合断屑槽型结构及双槽刀片断屑性能试验研究

现代可转位刀片的断屑槽型开始越来越多地使用复合断屑槽型结构。在本文中,我们首先介绍了几种比较典型的复合式断屑槽型：双槽、刀尖部分向前突起的结构、波浪形后背结构。然后采用最典型的复合式槽型─—双槽进行试验研究,并对其切削力和断屑性能分析说明。     

PCD刀具断屑槽参数仿生群算法优化北大核心

为提高PCD刀具使用寿命和Ti6Al4V钛合金工件表面质量,改善断屑效果,建立直线圆弧形断屑槽PCD刀具车削仿真模型,通过响应面法研究断屑槽参数(前角α、棱带长度L、曲率半径R)对切削力、刀尖温度和工件表面残余应力的影响,建立切削性能随断屑槽参数变化的二次多项式回归模型,应用方差分析和显著性检验验证模型的准确性。根据线性加权法,构建以切削力、刀尖温度和残余应力为目标的多目标优化模型,通过仿生群算法进行断屑槽参数优化。实验结果表明,PCD刀具断屑槽最优参数为前角α=30°、棱带长度L=0.1 mm、曲率半径R=0.42 mm。优化断屑槽参数后的PCD刀具能够有效降低切削力、刀尖温度和工件表面残余应力,改善断屑性能,形成规则的螺卷屑或长紧卷屑。     

三维槽形可转位硬质合金刀片断屑性能的实验研究(1)

本文系统地考察了从国外引进的五种可转位硬质合金刀片的实际断屑民性能．观察了切屑的形态，分析了折断机理．总结出加工参数的变化影响切屑流向、卷曲及折断的规律．最后探讨了目前刀片槽形设计的趋向．     

刀片断屑槽性能的模糊（FUZZY）综合评判

在淬火和回火后，１８Ｃｒ２Ｎｉ４ＷＡ，４２ＣｒＭｏ，４０Ｃｒ等合金钢和２Ｃｒ１３不锈钢可获得良好的综合性能，但这给加工带来了困难，其主要的问题之一是断屑，通过大量断屑试验和研究，作者设计和制造了三种在仿形车床上车削用的可转位刀片。通过利用模糊理论，作者试图对三种断屑槽的断屑性能作出模糊综合评判，其效果是满意的。     

316L不锈钢车削用刀片的槽型结构对切削性能的影响

316L具有优良的耐腐蚀性能,是目前较为广泛应用的奥氏体不锈钢。本文以316L不锈钢为研究对象,选择EM（大前角）、SM3（小反屑角）、MM（小前角）、SF（大反屑角）等四款槽型结构的硬质合金刀片,在半精加工的加工参数下进行切削加工,研究不锈钢车削刀片不同槽型几何结构对切削性能的影响规律。结果表明：EM和MM刀片切削力相对最低,刀片槽型反屑角越小,切削力越小,结合槽型特征说明合理的双前角设计利于减小切削力;刀片的断屑能力主要与反屑角的大小以及进给量有关,在不引起切削力显著增大的前提下,将反屑角设计在20°左右,可以获得良好的断屑性能;MM刀片在小进给和切削深度下加工表面粗糙度较好,但受到工艺参数显著影响,EM刀片加工表面粗糙度最佳且稳定;从四种刀片的磨损情况来看,EM刀片在半精加工的工艺参数下抗磨损性能最佳。     

可转位刀片复杂断屑槽断屑机理探讨

本文采用接触图形法和切屑折断性模糊估计等方法，对国外流行的可转位刀片复杂断屑槽的断屑机理进行了实验研究。研究结果表明：为了扩大断屑范围、改善断屑性能，这些断屑槽均采取了根据不同吃刀量和进给量改变有效槽宽，使切屑横截面弯曲、弹性挡屑、断屑槽形状、棱带宽度和刀尖圆弧半径的有机结合等措施。这些对于新型断屑槽型的开发具有重要意义。     

硬质合金可转拉车刀片UG型断屑槽断屑机理的研究

本文采用接触图形法对硬质合金可转位车刀片ＵＧ型断屑槽的断屑机理进行了实验研究。结果表明：由于采用了根据不同切削深度和进给量巧妙改变有效槽宽、使切屑横截面弯曲呈拱形、弹形挡屑等措施，ＵＧ型断屑槽具有断屑范围较宽、在进给量较大时不易出现过分断屑等特点。此外，文中还对化学气相涂层刀片的ＵＧ型断屑槽在切削速度明显提高以后断屑范围的变化进行了研究。文中给出的ＵＧ型断屑槽的断屑范围图可供实际选用。     

Analysis of a new Segmentation Intensity Ratio “SIR” to characterize the chip segmentation process in machining ductile metals

In machining, chip morphology has an important effect on several cutting parameters such as tool wear, chip flow, vibration, etc. This research work aims to analyse the chip segmentation phenomenon for ductile metals. The aeronautical aluminium alloy A2024-T351 has been selected for the study. Using Finite Element modelling, segmentation process has been analysed and quantified with a new physical parameter called “Segmentation Intensity Ratio”. The SIR parameter which leads to a better analysis of the chip morphology is defined as a ratio between the equivalent plastic strain inside and outside shear bands within the chip. Using this parameter the effect of cutting conditions and tool geometry on the chip segmentation can be clearly shown. Also the fluctuation of the contact length, the tool-chip interface temperature as well as the cutting force oscillations with respect to cutting speed are carefully discussed when segmentation occurs. A correlation between chip formation process and cutting force oscillation is established as well as a correlation between average cutting force reduction and segmentation intensity when cutting speed increases. Finally, a parametric analysis was conducted to highlight the effect of the friction on the chip segmentation intensity.     

Development of a chip flow model for turning operations

A model is presented which predicts the chip flow direction in turning operations with nose radius tools under oblique cutting conditions. Only the tool cutting edge geometry and the cutting conditions (feed and depth of cut) are required to implement the model. An experimental study has verified the chip flow model and shown that the model's predictions are in good agreement with the experimental results.     

数控车削切屑形态智能预测的动态建模及实时仿真

针对数控加工中切屑形成过程的监控问题,在基于实时工况智能监控平台上,通过研究切屑形态预测的智能动态建模方法（人工神经网络）,建立了切屑形态预测动态模型;并根据切屑空间运动轨迹的数学模型,建立了切屑三维造型模型,并在虚拟现实环境中实现车削过程的切屑实时动态仿真.     

Development of a High Performance End Mill Based on the Analysis of Chip Flow Generated by Curved Rake Face

To achieve high efficiency machining with end mills, the analysis of chip flow is necessary. Firstly, the constraints which a curved rake face gives to chip flow are analyzed, and the existence of the third component of angular velocity of the chip, which is different from those of up-curl and sideward curl, is found. Secondly, based on the analysis, a simulation model of chip flow is proposed, thus leading to the development of a high performance end mill. Finally, the chip configurations and chip flow obtained by the simulation are compared with those observed in actual cutting tests for verification.     

Chip thickening in deep-hole drilling

In conventional turning and milling cutting process models, chips are free of external forces after leaving the cutting area. However, in a drilling process, chip flowing is constrained by the drill flute, causing the change of chip shape and drilling forces. In this research, it is found that when drilling deep holes, the chip thickness increases as drilling progresses deeper into the workpiece. It is also found that during a deep-hole drilling process a significant part of the drilling force increase is due to the chip thickening effect. An analytical model was developed to predict the force increase caused by chip thickening. Experiments have been carried out to verify the model.     

A new material model for 2D numerical simulation of serrated chip formation when machining titanium alloy Ti–6Al–4V

A new material constitutive law is implemented in a 2D finite element model to analyse the chip formation and shear localisation when machining titanium alloys. The numerical simulations use a commercial finite element software (FORGE 2005^®) able to solve complex thermo-mechanical problems. One of the main machining characteristics of titanium alloys is to produce segmented chips for a wide range of cutting speeds and feeds. The present study assumes that the chip segmentation is only induced by adiabatic shear banding, without material failure in the primary shear zone. The new developed model takes into account the influence of strain, strain rate and temperature on the flow stress and also introduces a strain softening effect. The tool chip friction is managed by a combined Coulomb–Tresca friction law. The influence of two different strain softening levels and machining parameters on the cutting forces and chip morphology has been studied. Chip morphology, cutting and feed forces predicted by numerical simulations are compared with experimental results.     

Continuous chip formation in drilling

The formation of coil continous chips in drilling often leads to chip disposal problems. This paper investigates the drill chip formation process of continuous chips (spiral chips and string chips). Chip removing motions and forces are analyzed. Two models are developed to predict the spiral and string chip formation, respectively. Based on the level of bending due to the chip generation at the cutting edge and deflection by the flute, these models qualitatively investigate relationship of the point angle and flute helix angle on the average chip length. Drilling experiments validate the chip length for spiral and string chip predicted by both models.     

基于BTA深孔钻钻削EA4T钢的切屑形成机制研究

通过BTA深孔钻钻削EA4T钢的实验,探究在切削EA4T钢过程中切屑的形成机制。通过统计不同的切削用量所对应的切屑类型,进而分析用BTA深孔钻钻削EA4T钢过程中改变切削用量对切屑形态的影响。在此基础上反推出BTA深孔钻钻削EA4T钢时,切削用量的实际控制范围,为实际生产提供一定的理论依据。实验结果显示用BTA深孔钻钻削EA4T钢,分屑、断屑效果良好,并且可以在很大的范围内以不同的切削速度或进给量都能得到较理想的C型屑。     

Analytical predictions and experimental validation of cutting force ratio, chip thickness, and chip back-flow angle in restricted contact machining using the universal slip-line model

This paper presents analytical predictions and experimental validation of a recently developed universal slip-line model for machining with restricted contact cut-away tools. Three important machining parameters, i.e. the cutting force ratio, chip thickness, and chip back-flow angle, are predicted on the basis of: (1) the universal slip-line model; (2) a maximum value principle for determining the state of stresses in the plastic region in restricted contact machining; (3) Dewhurst and Collins’ matrix technique for numerically solving slip-line problems; and (4) Powell’s algorithm for non-linear optimizations. All predictions are based on purely theoretical calculations with no experimental/empirical data as input. The extensive comparisons between theory and experiments show a reasonable agreement. Major new research findings from this study include: (1) the applicable ranges of an extreme friction slip-line model and of Johnson’s and Usui and Hoshi’s slip-line models; and (2) the general rule of the variation of tool–chip friction conditions. Tool–chip contact in machining with restricted contact cut-away tools is categorized into three broad cases. A theoretical method is also presented in the paper to distinguish different tool–chip contact cases in practical machining situations.