钛合金零件高速铣削刀具磨损的试验研究

高速铣削钛合金时,由于切削区内的切削温度高,加剧了刀具的磨损。通过对钛合金TC4的高速铣削实验,得出带TiA lN涂层的硬质合金刀具切削钛合金TC4时的刀具磨损的变化规律和刀具耐用度公式。通过对刀具磨损特性的分析,研究结果主要是刀具表面层的粘结相Co在高温下丧失对WC颗粒的结合强度,磨损机理以高温下的粘结层撕裂磨损为主。     

钛合金铣削刀具磨损对表面完整性影响研究

为了掌握钛合金TC4铣削过程中刀具磨损对表面完整性的影响规律,通过对不同刀具后刀面磨损量下铣削钛合金工件的表面完整性测试,得出了刀具磨损对表面完整性的影响规律,并对其影响机理进行了分析.结果表明,在刀具处于初期磨损和正常磨损阶段,刀具的挤光效应引起的压应力占主导地位,而在刀具剧烈磨损阶段,加工过程中的热塑性变形引起的拉应力占主导地位;随着刀具后刀面磨损量的增加,刀具正常磨损阶段粗糙度值缓慢增加,剧烈磨损阶段粗糙度值迅速增加;随着刀具后刀面磨损量的增加,已加工表面的显微硬度值和表面层的硬化深度都随之增大.     

高速铣削Ti-10V-2Fe-3Al的刀具磨损试验研究

针对切削加工Ti-10V-2Fe-3Al钛合金时刀具磨损迅速、加工效率低的问题,开展硬质合金刀具高速铣削Ti-10V-2Fe-3Al的刀具寿命试验,以研究刀具的磨损机理,分析刀面磨损的发展以及对切削力的影响。利用扫描电子显微镜观察了后刀面磨损区域的微观形貌并对元素成分进行了能谱分析。实验结果表明：高速铣削Ti-10V-2Fe-3Al时硬质合金刀具的磨损形式为后刀面带状磨损与局部崩刃,伴有明显的切屑黏附与热裂纹;磨损区域有工件材料的元素向硬质合金内扩散的迹象出现;切屑流的黏附与撕扯导致硬质合金的颗粒脱落,切削刃逐步退化为洼形区域,其与后刀面交界的棱边代替原切削刃进行切削直至剥落。     

硬质合金刀具高速车铣和铣削TC4钛合金磨损试验对比

采用H13A未涂层硬质合金刀具对TC4钛合金进行高速正交车铣和铣削试验,并从刀具磨损破损形态、磨损机理及其寿命等方面进行对比分析。研究表明:高速正交车铣和铣削钛合金时,前、后刀面主要以粘结磨损为主,车铣加工时在切削刃口易形成积屑瘤及连续切屑,但对刀具材料粘结较轻;高速铣削时,对刀具材料粘接较重,在前刀面刃口附近形成凹坑及崩刃;后刀面最大磨损的位置不相同。试验对比了相同切削条件时刀具使用寿命,结果表明采用正交车铣加工可以获得更长的刀具使用寿命。     

钛合金铣削加工刀具磨损有限元预测分析

钛合金Ti6Al4V因其优良的综合性能在航空航天领域有着广泛的应用。然而,在钛合金切削过程中,极易出现刀具磨损现象。目前尚缺乏钛合金加工用刀具寿命预测的有效手段和方法。针对这一问题,基于刀具在铣削工作过程中受到的热力耦合作用,利用Fick扩散定律揭示了刀具扩散磨损机理,构建刀具磨损模型;利用有限元仿真软件Advant Edge的二次开发技术,将刀具磨损模型嵌入到有限元模型中,进行刀具磨损的预测;进而借助刀具寿命试验,验证了刀具磨损模型的可靠性。     

氮气介质下铣削钛合金时的刀具磨损研究

通过大量的试验 ,对氮气介质下铣削钛合金时的刀具寿命和磨损特征进行了分析和研究 ,从而得出了在氮气介质下铣削钛合金比干铣削具有明显优势的结论 ,探讨了氮气介质下铣削钛合金时的刀具磨损机理。     

蜂窝状铝合金高速加工刀具粘附行为及其作用机理研究

通过高速铣削试验方法对蜂窝状铝合金高速铣削刀具的粘附行为及粘附机理进行了研究。结果表明,由于初期铝屑粘附在刀具表面上,致使后期切削加工中的铝切屑与刀具表面的化学活性近似,使得铝屑进一步强化粘附在刀具表面,且由于高速加工中产生的高温和高压作用,使得粘附层材料发生变形。后续切屑划擦初期的粘附层,使粘附层出现变形和犁沟现象,加剧刀具与工件间的摩擦状态。同时,铝合金高速加工中高的塑性变形特征是发生粘附磨损的另一重要作用机制。此外,切屑表层材料受到剧烈剪切变形引起表面积增加,使切削形成的金属表面膜破裂,在与刀具表面紧密接触的近乎为真空环境下刀具不断切削新的表面,活性非常高,极易发生摩擦化学反应,较高摩擦化学反应形成的表面厚度达到临界值时将发生磨损,导致刀具粘附磨损加剧。     

高速铣削时硬质合金刀具与NAK80模具钢化学性能匹配研究

高速铣削加工时温度较高,易引起刀具与工件之间产生化学反应,加剧刀具与工件磨损,缩短刀具寿命。实现刀具材料和工件材料的化学性能匹配,可有效保证模具型面加工质量和提高生产效率。化学性能匹配主要从刀具材料与工件材料的氧化以及扩散方面进行研究。通过理论计算得到刀具与工件材料的化学反应自由能;结合高温氧化试验,研究NAK80模具钢的高温氧化产物并探究其抗氧化性能;基于变系数浓度扩散模型,利用元素扩散试验获得了NAK80模具钢与刀具材料间的元素扩散强度。结果表明,NAK80模具钢的氧化程度随温度升高而加剧,温度高于1300K可发生完全氧化;NAK80模具钢中的Fe元素扩散深度随硬质合金刀具中Co元素含量的增加而增加。     

硬质合金刀具切削钛合金Ti6Al4V界面摩擦特性研究

钛合金Ti6Al4V具有高的比强度、良好的机械性能和抗蚀性,但因其化学活性大、导热系数低,切削时刀具磨损严重。为选择合理切削参数以减少刀具磨损,研究钛合金在不同切削条件下刀-屑/工界面的摩擦特性。结果表明,在切削速度较低时,刀具磨损表面紧密接触区附有大量黏结物,而在切削速度较高时,会产生不稳定粘结物,且刀具与工件材料接触面发生扩散,不稳定黏结物的脱落造成刀具微崩刃,加速刀具的磨损;采用合理的切削速度时,黏附在刀具表面的工件材料会发生氧化反应,生成的氧化物具有一定边界润滑作用,使黏结磨损与氧化磨损达到平衡,因此能减弱刀具-工件间接触时的高温黏结,降低刀具的磨损。     

TA15钛合金铣削试验及磨损分析

针对刀具磨损、切削力、粗糙度和铣削长度的关系,在切削液的条件下铣削TA15钛合金,研究硬质合金刀具整个加工过程中的刀具磨损、切削力、表面粗糙度和加工长度的关系,同时研究了刀具磨损对切削力和粗糙度的变化关系。结果表明:切削力随着铣削长度的增加而增加,涂层刀具的初期磨损阶段刀具磨损量及切削力上升缓慢;钛合金工件粗糙度随着铣削长度的增加先显著降低,再平稳上升,后显著上升;切削力随着刀具磨损增加而增加,粗糙度随刀具的磨损先显著降低,再逐渐增加。     

An online optical system for inspecting tool condition in milling of H13 tool steel and IN 718 alloy

Tool wear adversely affects surface integrity due to higher cutting forces and temperatures. However, an accurate and efficient tool wear measurement is a challenging problem. The traditional direct tool wear measurement methods such as optical microscope and scanning electron microscope (SEM) leads to error of tool reassembly, tool orientation, and low accuracy, while the indirect measurement methods cause poor accuracy. In this paper, tool wear phenomena in milling of tool steel AISI H13 and superalloy Inconel 718 have been studied. A novel online optical system has been developed to integrate with a CNC machine to directly inspect and measure tool wear conditions in milling which minimizes the above-mentioned measurement errors in traditional methods. The evolutions of tool flank wear of PVD-coated inserts in end milling of the two materials were inspected to demonstrate the function of the optical measurement system. The tool wear evolution versus cutting time were obtained and examined. The characteristic images of fast tool wear in milling of Inconel 718 were captured using SEM and compared with the optical images to estimate flank wear. Three basic modes of tool wear—flank wear, nose wear, and crater wear—were compared and analyzed. A two-parameter method has been developed to evaluate both flank wear and nose wear with respect to cutting time in milling of Inconel 718. The advantages of the on-line optical tool inspection system were discussed.     

CN35硬质合金涂层刀具高速车削淬硬钢的磨损与破损形态

借助于扫描电镜照片和能谱分析,对高速车削淬硬45钢时CN35硬质合金涂层刀具的失效形态及其机理进行了观察和分析。结果显示,在高速切削条件下,涂层刀具的失效形态主要分为破损与磨损两种,刀具正常磨损失效过程仍然遵循常规切削条件下三个阶段的程序。刀具破损失效发生在低速切削阶段,且随着切削速度的提高,破损部位由后刀面转移到前刀面;高速切削时,刀具失效形式倾向于后刀面磨损、边界磨损和切削刃斜面磨损,因高热、粘结、疲劳、氧化、扩散和热裂等原因造成刀具切削功能丧失。     

基于切削力的铣刀磨损在线监测研究

以实验方法研究了高速钢立铣刀后刀面磨损和铣削力之间的关系,建立了表征后刀面磨损和铣削力之间关系的数学模型,并提出了基于切削力的铣刀磨损监测算法。     

难加工材料铣削加工中刀具温度场的计算与试验

本文应用高速钢组织结构法对铣削加工时刀具温度场的分布进行了试验研究。并使用有限差分的方法对铣削加工区的三元非稳定的温度场进行了计算,在计算中对其边值条件的确定、差分格式的选用以及解的稳定性等问题进行了讨论。在选用适当的边值条件后,试验结果能够与计算结果较好地吻合。本研究揭示了在难加工材料的铣削加工中,刀具的后刀面貌类似于前刀面上的月牙形的温度分布,而且随着后刀面磨损带的扩大,这种后刀面的月牙形温度分布趋于更加明显。它也是造铣削难加工材料时后刀面磨损的主要原因。本研究对切削参数的选择、刀具的设计及加工表面质量的控制有一定的指导意义。     

An analytical approach to cutting force prediction in milling of carbon fiber reinforced polymer laminates

ABSTRACT

A prediction model of cutting force for milling multidirectional laminate of carbon fiber reinforced polymer (CFRP) composites was developed in this article by using an analytical approach. In the predictive model, an equivalent uniform chip thickness was used in the case of orthogonal plane cutting, and the average specific cutting energy was taken as an empirical function of equivalent chip thickness and fiber orientation angle. The parameters in the model were determined by the experimental data. Then, the analytical model of cutting force prediction was validated by the experimental data of multidirectional CFRP laminates, which shows the good reliability of the model established. Furthermore, the cutting force component of flank contact force was correlated with the surface roughness of workpiece and the flank wear of tool in milling UD-CFRP composites. It was found that surface quality as well as flank wear has a co-incident varying trend with the flank contact force, as confirmed by the observations of the machined surfaces and tool wear at different fiber orientations. So, it can be known that low flank contact force be required to reduce surface damage and flank wear.     

Tool wear rate prediction in ultrasonic vibration-assisted milling

Abstract

In the current study, a predictive model on tool flank wear rate during ultrasonic vibration-assisted milling is proposed. One benefit of ultrasonic vibration is the frequent separation between tool and workpiece as the cutting time is reduced. In order to account for this effect, three types of tool–workpiece separation criteria are checked based on the tool center instantaneous position and velocity. Type I criterion examines the instantaneous velocity of tool center under feed movement and vibration. If the tool is moving away from workpiece, there is no contact. Type II criterion examines the position of tool center. If the tool center is far from the uncut workpiece surface, there is no contact even though the tool is getting closer. Type III criterion describes the smaller chip size due to the overlaps between current and previous tool paths as a result of vibration. If any criterion is satisfied, the tool flank wear rate is zero. Otherwise, the flank wear rate is predicted considering abrasion, adhesion and diffusion. The proposed predictive tool flank wear rate model is validated through comparison to experimental measurements on SKD 61 steel with uncoated carbide tool. The proposed predictive model is able to match the measured tool flank wear rate with high accuracy of 10.9% average percentage error. In addition, based on the sensitivity analysis, smaller axial depth of milling, larger feed per tooth or higher cutting speed will result in higher flank wear rate. And the effect of vibration parameters is less significant.     

基于后刀面磨损的铣削加工误差研究

对铣削加工过程中后刀面磨损对加工精度的影响进行了分析和研究,建立了基于刀具后刀面磨损的铣削加工误差的数学模型。     

Modeling of cutting force under the tool flank wear effect in end milling Ti6Al4V with solid carbide tool

This paper presented a study of the relationship between cutting force and tool flank wear of solid carbide tool during the wet end milling Ti6Al4V. The modeling of 3D cutting force in end milling considering tool flank wear was discussed, which showed that for the given cutting conditions, tool geometries, and workpiece material, cutting force under the tool flank wear effect can be predicted easily and conveniently. In addition, the experimental work of end milling Ti6Al4V with solid carbide tool was developed to investigate the relationship between cutting force and tool flank wear, and comparison between experimental results and predicted results was discussed. The results showed that the proposed mathematical model can help to predict 3D cutting force under the tool flank wear effect with high accuracy.     

Prediction of flank wear and engagements from force measurements in end milling operations

On-line knowledge of tool engagement and flank wear is critical for successful adaptive control of a machining operation. A method combining a mechanistic model and empirical relationships has been developed for helical end milling operations. Computation of cutting tool engagements and flank wear width occurs in real time as the cutting progresses using averaged force data. Response surface methodology has been used to investigate the effects of the process and operating variables on the process-dependent parameters; a second order relationship was obtained. The approach can also determine variation of wear land width along the length of the tool as axial engagement changes.     

PCD刀具高速铣削GH4169合金的刀具磨损规律研究

为研究PCD刀具高速铣削GH4169合金时刀具的磨损规律,采用单因素试验法分别对不同铣削参数下后刀面磨损程度随切削路程的变化进行对比。结果显示主轴转速对高速铣削GH4169合金时刀具磨损的影响不大,采用顺铣、切削液冷却的方式,并适当降低每齿进给量有助于减小刀具磨损。使用BP神经网络对试验数据进行训练,建立了刀具磨损预测的模型,预测结果与实际结果误差在5%以内。