平面拉刀磨损有限元分析

拉削加工过程中,刀齿在切削力、热耦合作用下较易产生磨损。由于高速拉削技术的发展,拉刀刀齿前刀面的磨损逐渐引起了更多的关注。随着拉削的进行,刀齿的磨损量不断增加。通过有限元分析,确定了拉削速度、齿升量、刀尖圆弧半径对前刀面磨损带深度和宽度的影响。     

高速铣刀差异化振动磨损形成机制及其控制方法

高速铣削过程中,受刀齿结构和误差的影响,铣刀多个刀齿的振动特性和与工件的动态接触关系有明显不同,由此导致的铣刀多齿振动磨损程度差异性明显,铣刀整体使用寿命下降已成为高速铣削加工亟待解决的问题。本文进行了高效铣削加工实验,提取铣刀振动时域/频域特征参数以及刀齿磨损宽度,采用改进的灰色关联法对铣刀振动特性与铣刀磨损的关联性进行分析。构建铣刀振动条件下刀齿—工件接触关系模型,揭示铣刀多齿切削振动差异化磨损特性及其形成条件,提出铣刀振动磨损的控制方法。结果表明,采用所提出的控制方法能够正确识别铣刀多齿振动磨损的影响因素,并对铣刀多个刀齿的差异化磨损实现有效控制。     

立铣刀渐进磨损过程中主电机功率信号的时域特性研究

根据立铣刀刀齿渐进磨损过程中主轴电机功率信号的变化特点 ,分析了主轴电机功率与刀齿后刀面磨损带面积 (AVB)间模型的时域统计特性 ,提取了反映刀具磨损状态的时域统计特征参数。相关试验证明了研究结果的正确性。     

径向跳动对球面铣刀切削力的影响研究

研究了径向跳动对刀齿的实际切削半径、切屑形状以及切屑厚度的影响机理。研究了各刀齿沿刀刃螺旋线的切削微元实际切削半径的数学表示和变化规律,实际切削半径的变化改变了刀齿的切削路径,使各刀齿上切屑形状分布不均匀。建立了三维切削下切屑厚度的数学表示,提出了递延累加切屑厚度计算算法。实验验证表明,计算的切削力与测量结果能很好地吻合,瞬时切削力、切削力峰值、平均切削力的预测精度达到85%以上。     

硬旋铣刀具振动的在线监测研究

针对螺纹硬旋铣过程中刀具振动状态的辨识问题开展试验研究.根据硬旋铣的工艺特点设计刀齿切削力监测系统及切削试验,对切削力数据进行频域分析.研究结果表明:硬旋铣机床的刀具切削振动是由断续切削引起的强迫振动无自激振动发生的.     

自适应随机共振算法的立铣刀磨损信号检测

在对刀具磨损信号的检测过程中,强噪加工环境使得所需特征信号显得非常微弱,给提取微弱特征信号带来了难题,基于此问题提出了利用自适应随机共振算法对立铣刀在磨损过程中产生的磨损信号进行检测,用加速度传感器和力传感器采集振动信号和切削力信号,再将提取的信号进行时频域的特征值提取,以此来分别建立遗传算法和粒子群算法优化的自适应随机共振模型,最后将这两种模型都用在对立铣刀的磨损检测中。实验结果表明,遗传算法和粒子群算法均可检测出立铣刀转动频率和刀齿切入频率,以及这两种频率下所对应的立铣刀磨损信号,为日后立铣刀磨损状态在线监测系统的建立奠定了基础。     

变螺旋铣刀切削力建模及影响因素分析

变螺旋铣刀可降低加工过程表面位置误差,进而提高加工精度。考虑变螺旋铣刀的变端齿距和变螺旋角几何特性及刀齿的切削过程分段特性,构建了变螺旋铣刀每齿进给量时变模型和切削力预测解析模型。开展了铣削实验,验证了模型的有效性和可靠性。基于理论模型,进行了变螺旋铣刀切削力影响因素分析,结果表明:常规铣刀实验所得的切削力系数,可用于变螺旋铣刀切削过程切削力预测;铣刀变螺旋角特性可显著影响切削力,刀齿螺旋角度越大,其切削力峰值越小,而每齿的切削力相位宽度随着螺旋角的增大而增大;铣刀变螺旋角特性对切削力的影响在大轴向切削深度时更为显著。     

钛合金宽弦空心风扇叶片榫齿成型铣削研究

针对钛合金宽弦空心风扇叶片榫齿加工需求,采用硬质合金成形铣刀进行了钛合金铣削加工试验,通过切削力频域特性分析优化了切削参数,并对精加工条件下工件轮廓精度和表面完整性进行了分析。结果表明:切削速度对切削力频域幅值有显著影响,结合工件表面形貌和刀具磨损状况优选切削速度范围80-100m/min;成型铣削精加工条件下,工件轮廓精度满足要求,工件表面纹理清晰,表面粗糙度Ra在0.4μm左右,表层存在轻微硬化,未发现明显相变、晶粒粗大和晶粒扭曲现象。研究结果可为钛合金榫齿成型铣削工艺参数优化提供指导。     

TiAlN涂层硬质合金可转位刀具快速铣削钛合金刀片磨损研究

快速铣是一种新兴的粗加工方法,研究它的刀具磨损机理对提高刀具寿命和加工效率有着重要的作用。采用硬质合金快速铣刀片在工件上进行了钛合金TC17铣削实验,研究了不同切削参数对切削力的影响,采用多元线性回归建立了切削力数学预测模型,分析了各铣削参数对切削力的影响规律,通过对后刀面的检测,分析了刀具磨损形貌和磨损机理。结果表明:每齿进给量、切削深度对切削力的大小影响显著,切削宽度和主轴转速影响很小,在试验参数范围内,选用切削参数组合为:f_z=0.8 mm/z、a_p=0.5 mm、a_e=20 mm、s=600 r/min进行可转位刀片的磨损试验,快速铣可转位刀片的主要磨损形貌为后刀面磨损、材料剥落,后刀面主要磨损机理为黏结磨损,同时会产生一定程度的扩散磨损。     

基于神经网络的BTA刀具磨损量预测

用单齿BTA刀具进行深孔钻削时,刀具磨损通常以刀齿后刀面磨损为主。本文提出一种基于人工神经网络的后刀面磨损值预测方法,采用试验设计的方法进行BTA钻削试验,通过万能工具显微镜来测量刀齿后刀面的磨损值,得到训练样本。通过有限的训练样本建立关于切削速度、进给量和轴向力的刀齿后刀面磨损量的预测模型,然后运用MATLAB进行仿真与计算。试验和仿真结果表明,该模型能有效预测刀齿后刀面磨损值,为减少刀具磨损提供了依据。     

基于时域特性的铣刀磨损状态信息提取

在分析铣削加工过程特点的基础上，采用后刀面磨损带面积为铣刀磨损的评价指标，建立了基于切削力和主轴电机功率的铣刀磨损模型，探讨了基于时域特性的铣刀磨损状态信息提取的相关技术。理论分析和实验结果表明，切削力和主轴电机功率的量纲一系数Cv的变化与铣刀后刀面磨损带的磨损过程直接相关。采用切削力和主轴电机功率的量纲一系数Cv作为铣刀后刀面磨损带面积的监测信号能真实地反映其磨损过程。     

曲面铣削过程加工路径对切削力和磨损的影响研究

针对不同走刀路径下的复杂曲面加工过程进行球头铣刀铣削Cr12MoV加工复杂曲面研究,分析不同走刀路径下铣削力和刀具磨损的变化趋势。试验结果表明:通过对比分析直线铣削和曲面铣削过程中的最大未变形切屑厚度,可以得出单周期内曲面铣削的力大于直线铣削过程的力,铣削相同铣削层时环形走刀测得的切削力普遍大于往复走刀测得的切削力;以最小刀具磨损为优化目标,运用方差分析法分析得出不同走刀路径的影响刀具磨损的主次因素,同时利用残差分析方法建立球头铣刀加工复杂曲面刀具磨损预测模型,并通过试验进行验证。     

Balancing the transverse cutting force during inclined milling and effect on tool wear: application to Ti6Al4V

The present article studies the effect on cutter wear of balancing transverse cutting forces during inclined milling applied to a titanium alloy (Ti6Al4V). Indeed, this method is advantageous as it helps reduce vibrations as also the amplitude of such forces thanks to balancing. These observations provide the means to enhance cutting conditions and thus boost productivity when roughing. The method was first validated on Ti6Al4V titanium alloy. A model was then proposed to estimate the maximum axial cutting force at angular positions 0 and p. A wear test was then conducted and notching, flaking and flank types of wear were observed as being most representative. Roughness measurements were made throughout the wear test as also measurements of cutting forces with a new cutter and the worn cutter to provide a comparison. The cutting forces remained acceptable and the roughness values measured remained below the criteria generally retained for roughing. The improvements obtained in terms of extended tool life when using this method were extremely significant since under the same cutting conditions flat milling gave a lifetime of 2.03 min while when machining with balancing of the transverse cutting forces this was extended to 23.6 min.     

Cutting Force Model for a Small-diameter Helical Milling Cutter

In the milling process, the major flank wear land area (two-dimensional measurement for the wear) of a small-diameter milling cutter, as wear standard, can reflect actual changes of the wear land of the cutter. By analyzing the wearing characteristics of the cutter, a cutting force model based on the major flank wear land area is established. Characteristic parameters such as pressure parameter and friction parameter are calculated by substituting tested data into their corresponding equations. The cutting force model for the helical milling cutter is validated by experiments. The computational and experimental results show that the cutting force model is almost consistent with the actual cutting conditions. Thus, the cutting force model established in the research can provide a theoretical foundation for monitoring the condition of a milling process that uses a small-diameter helical milling cutter.     

铣削TC4钛合金的刀具磨损对比试验

TC4钛合金是典型难加工材料之一,极易造成工具磨损。本文通过铣削TC4钛合金试验,跟踪铣削过程中铣刀每个齿的磨损量及磨损形态,比较了不同细晶粒硬质合金铣刀的磨损过程。结果表明,铣刀切削刃发生崩刃会直接缩短铣刀的使用寿命。     

Cutting force prediction for ball nose milling of inclined surface

Ball nose milling of complex surfaces is common in the die/mould and aerospace industries. A significant influential factor in complex surface machining by ball nose milling for part accuracy and tool life is the cutting force. There has been little research on cutting force model for ball nose milling on inclined planes. Using such a model ,and by considering the inclination of the tangential plane at the point of contact of the ball nose model, it is possible to predict the cutting force at the particular cutting contact point of the ball nose cutter on a sculptured surface. Hence, this paper presents a cutting force model for ball nose milling on inclined planes for given cutting conditions assuming a fresh or sharp cutter. The development of the cutting force model involves the determination of two associated coefficients: cutting and edge coefficients for a given tool and workpiece combination. A method is proposed for the determination of the coefficients using the inclined plane milling data. The geometry for chip thickness is considered based on inclined surface machining with overlapping of previous pass. The average and maximum cutting forces are considered. These two forces have been observed to be more dominating force-based parameters or features with high correlation with tool wear. The developed cutting force model is verified for various cutting conditions.     

A New NC Machine Tool Controller for Step-by-Step Milling

The paper describes the design sloution, operation and analysis of a new NC controller for a new step-by-step milling procedure. A step-by-step milling device ensures that the milling of workpieces by end or conical milling cutters, where the ratio between the depth of milling a (mm) and the milling cutter diameter D (mm) is greater thab 1.5 (a/D>1.5) results in the increased wear resistance of the cutting edge. Breaking of the milling cutter is minimised and is not frequent and the milling forces are reduced, which results in smaller deflections of the milling tool and higher accuracy of machining. The machine tool use is better.     

Improved dynamic cutting force model in peripheral milling. Part II: experimental verification and prediction

Cutting trials reveal that a measure of cutter run-out is always unavoidable in peripheral milling. This paper improves and extends the dynamic cutting force model of peripheral milling based on the theoretical analytical model presented in Part I [1], by taking into account the influence of the cutter run-out on the undeformed chip thickness. A set of slot milling tests with a single-fluted helical end-mill was carried out at different feed rates, while the 3D cutting force coefficients were calibrated using the averaged cutting forces. The measured and predicted cutting forces were compared using the experimentally identified force coefficients. The results indicate that the model provides a good prediction when the feed rate is limited to a specified interval, and the recorded cutting force curves give a different trend compared to other published results [8]. Subsequently, a series of peripheral milling tests with different helical end-mill were performed at different cutting parameters to validate the proposed dynamic cutting force model, and the cutting conditions were simulated and compared with the experimental results. The result demonstrates that only when the vibration between the cutter and workpiece is faint, the predicted and measured cutting forces are in good agreement.     

可补偿切削刃磨损的不铲齿成形铣刀的设计与制造

研制了一种可补偿切削刃磨损量的不铲齿成形铣刀 ,介绍了这种刀齿可调的装配式刀具的设计与制造方法。该刀具经反复重磨后 ,仍可保持切削刃的尺寸、形状参数和加工精度不变 ,且刀齿齿背曲线为圆弧过渡 ,不需铲齿。     

螺旋棒铣刀铣削力建模与仿真

在对螺旋棒铣刀铣削力建模中考虑了切削厚度变化对铣削力影响的指数关系、铣刀偏心对实际切削厚度、切入与切出角、铣削力波动的影响,并提出采用实测各刀齿铣削最大值比求解铣刀偏心和识别铣削力系数的方法。在考虑铣刀偏心因素的情况下仿真与实测的铣削力达到非常好的一致性。提出的铣削力仿真方法充分反映了铣削力的实际状态,提高了铣削力仿真精度。