基于Fluent的涂层刀具切削热传导研究

切削过程中,第二变形区刀具前刀面和切屑底部摩擦产生的热量通过刀—屑接触面流入到刀具体中,进而引起刀具温度的升高,过高的刀具温度会降低刀具强度,缩短刀具寿命。本文基于Fluent固体能量方程构建刀—屑接触面传热有限元模型,探讨涂层刀具在切削H13淬硬模具钢时涂层材料、涂层厚度和刀—屑实际接触面积对刀—屑接触面传热的影响规律。研究结果表明:在相同的刀—屑接触面温度和相同的涂层厚度条件下,Al2O3涂层对切削热传导的阻碍作用最为明显;涂层越厚,则刀—屑接触面处温差越大,较厚的刀具涂层能够有效降低刀具体内温度;刀—屑的不完全接触对刀—屑接触面处的热传导影响较大,随着刀—屑实际接触面积的减少,刀—屑接触面处的温差逐渐增加,减小刀—屑实际接触面积有利于降低刀具体内温度。     

断屑槽结构对Inconel 718镍基高温合金切削温度的影响研究

镍基高温合金强度高,在切削过程中产生的温度较高。基于ABAQUS有限元软件建立Inconel 718镍基高温合金三维切削仿真模型,通过单因素实验法研究断屑槽槽型结构对切屑形态与切削温度的影响。结果表明,不同断屑槽结构对切屑形态影响较大,并影响刀尖温度与最大切削温度。其中,梯形断屑槽与直弧形断屑槽相较于圆弧断屑槽与折线形断屑槽在断屑能力与切削温度等方面表现更优秀,这两种断屑槽刀具断屑及时,最大切削温度较低,切削温度变化较为平缓,更有利于提高工件表面质量和延长刀具使用寿命。     

钛合金锯齿状切屑形态模拟研究

利用有限元软件建立了钛合金(Ti6Al4V)的切削模型,得到锯齿状切屑的应力场、应变场及温度场,探讨了锯齿状切屑的形成机理,同时模拟了不同切削参数对锯齿状切屑形态的影响。结果表明:切削速度、进给量和刀具前角对锯齿状切屑形态的影响规律相似,即锯齿频率随切削速度、进给量和刀具前角的增加而增大。刀-屑摩擦因数对锯齿状切屑形态无明显影响,但切削力、刀-屑接触长度随刀-屑摩擦因数的增加而增大。换热系数对切削温度影响较大,换热系数越大,对切削温度降温效果越明显。对切削温度的抑制效果由低温冷风雾化射流冷却、水射流冷却、低温冷风冷却依次减弱,但都优于干切削。     

高速切削30CrNi3MoV淬硬钢切屑形成机理的试验研究

通过30CrNi3MoV淬硬钢的高速切削试验,观察和测量不同切削条件下切屑形态的演变过程、锯齿状切屑形成的临界切削条件、切削力.结果表明,切削速度和刀具前角是影响切屑形态和切削力的主要因素,随着切削速度的提高,在某一临界切削速度下,切屑形态由带状屑转变为锯齿状切屑,随着刀具前角由正前角逐渐变为负前角,临界切削速度明显减小,当锯齿状切屑形成时,切削力大幅度降低.使用金属切削过程中绝热剪切临界切削条件判据对锯齿状切屑形成临界切削速度预测的结果表明,锯齿状切屑形成的根本原因是主剪切区内发生周期性的绝热剪切断裂.     

不同涂层刀具铣削退火H13钢加工性能研究

为了研究退火后的H13钢的切削加工性能,采用多种Ti化合物涂层刀具进行铣削退火H13钢试验,分析了不用的涂层材料刀具与切削力、切屑形态以及刀具磨损状况之间的关系。研究得出:TiAlN涂层刀具受到三个方向的力比TiN涂层刀具以及TiC涂层刀具受到的力小;TiAlN涂层刀具切削后后刀面磨损较小,TiN涂层刀具次之,TiC涂层刀具后刀面损伤面积最大;TiAlN涂层刀具切削产生的切屑大多呈现细长卷曲的形状,且切屑长度适中,切削性能最佳。     

基于刀具磨损和切屑形成对切削Ti6Al4V的切削力特性研究

为了研究钛合金Ti6Al4V切削过程中的切削力特性,采用硬质合金涂层和无涂层刀具进行了外圆干车削试验,提取切削力信号,通过研究切削力的静动态特性,揭示了切削力与切削速度、刀具材料、刀具磨损以及切屑形成的关系.结果表明:钛合金切削过程中,切削力的静态分量中径向力Fp最大,直接导致刀具后刀面磨损;随着切削速度的变化,切削力的变化是由刀具磨损、材料本身的特性等多方面因素综合作用的结果,切削力动态分量分形维数可用于刀具状态监控;锯齿形切屑的产生与切削力的高频变化有直接的关系,锯齿生成频率可以作为切削力动态分量频率的一个表征,选取适当的切削参数可以降低由于锯齿屑产生引起的切削力振动.     

Ti-Si-C涂层刀具切削淬火钢性能研究

采用磁控溅射法在硬质合金YT15和YS25两种刀具基体上制备了Ti-Si-C涂层刀具,通过测量干式切削45#淬火钢下,切削力、切削温度、刀具磨损以及切屑形态变化情况,来综合评价Ti-SiC涂层刀具的切削性能。结果表明:相对于未涂层刀具,施加Ti-Si-C涂层的刀具切削力得到部分减小,切削温度得到显著降低。Ti-Si-C涂层对减小刀具的磨损起到一定的作用。     

微织构衍生切削下的钛合金正交微切削性能分析

针对微织构刀具加工过程中的衍生切削效应,利用正交微切削单元开展了微坑刀具及无织构刀具的钛合金微切削实验,从切屑底面形貌、微坑黏结状态等方面分析了微坑刀具微切削性能;通过ABAQUS软件对微织构刀具微切削钛合金过程进行有限元模拟,分析微坑织构的衍生切削作用对刀-屑接触应力分布及切削力的影响,优化设计微坑边缘过渡区参数并进行切削仿真分析。实验和仿真结果表明,微坑会减小前刀面黏结,存储微屑,减小刀-屑接触应力,提高刀具减摩性能;但微坑与切屑的衍生切削作用会增大瞬时切削力,降低切削过程平稳性。此外,微坑过渡区优化可改善切削过程波动,降低切削力,改变切屑形态,改善切屑在微坑的流入/流出状态,有助于减小微坑织构衍生切削效应,提高织构的减摩效果。     

镍基高温合金切削加工锯齿形切屑研究

以镍基高温合金GH4169和GH3030为研究对象,采用未涂层和涂层刀具进行车削加工试验,通过对金相、切削力、切削温度及刀具磨损形态的检测,阐明锯齿形切屑形成的机理,并对两种材料的切削加工性进行比较。研究结果为该类材料切削工艺的优化提供了试验依据。     

低温微量润滑切削304不锈钢的实验研究

低温MQL切削是低温冷风与微量润滑（MQL）相结合的一种绿色环保加工技术。采用改造的YT15刀具对304不锈钢进行低温MQL切削实验,并比较干切削、湿切削、低温MQL切削三种方式对工件的表面粗糙度以及切屑形态的影响。结果表明,低温MQL采用高压低温冷风冷却润滑,高压冷风可直接将润滑油带入刀-屑和刀-工件接触区域,起到更好的润滑作用,有效降低切削区的温度;相对干切削和湿切削,低温MQL切削能明显降低表面粗糙度,改善其断屑性能,获得较好的切屑形态。     

Evaluation on Effectiveness of CVD and PVD Coated Tools during Dry Machining of Incoloy 825

With wide applications of nickel-based superalloys in strategic fields, it has become increasingly necessary to evaluate the performance of different advanced cutting tools for machining such alloys. With a view to recommend a suitable cutting tool, the present work investigated various machinability characteristics of Incoloy 825 using an uncoated tool, chemical vapor deposition (CVD) of a bilayer of TiCN/Al₂O₃, and physical vapor deposition (PVD) of alternate layers of TiAlN/TiN-coated tools under varying machining conditions. The influence of cutting speed (51, 84, and 124 m/min) as well as feed (0.08, 0.14, and 0.2 mm/rev) was comparatively evaluated on surface roughness, cutting temperature, cutting force, coefficient of friction, chip thickness, and tool wear using different cutting tools. Although the CVD-coated tool was not useful in decreasing surface roughness and temperature, a significant reduction in cutting force and tool wear could be achieved with the same coated tool under a high cutting speed of 124 m/min. On the other hand, the PVD-coated tool outperformed the other tools in terms of machinability characteristics. This might be attributed to the excellent antifriction and antisticking property of TiN and good toughness due to the multilayer configuration in combination with a thermally resistant TiAlN phase. Adhesion, abrasion, edge chipping, and nose wear were the prominent wear mechanisms of the uncoated tool, followed by the CVD-coated tool. However, remarkable resistance to such wear was evident with the PVD TiAlN/TiN multilayer-coated tool.     

High-Speed Machining of Malleable Cast Iron by Various Cutting Tools Coated by Physical Vapor Deposition

The coating material of a tool directly affects the efficiency and cost of machining malleable cast iron.However,the machining adaptability of various coating materials to malleable cast iron has been insufficiently researched.In this paper,turning tests were conducted on cemented carbide tools with different coatings(a thick TiN/TiAlN coating,a thin TiN/TiAlN coating,and a nanocomposite(nc)TiAlSiN coating).All coatings were applied by physical vapor deposi-tion.In a comparative study of chip morphology,cutting force,cutting temperature,specific cutting energy,tool wear,and surface roughness,this study analyzed the cutting characteristics of the tools coated with various materials,and established the relationship between the cutting parameters and machining objectives.The results showed that in malleable cast iron machining,the coating material significantly affects the cutting performance of the tool.Among the three tools,the nc-TiAlSiN-coated carbide tool achieved the minimum cutting force,the lowest cutting tempera-ture,least tool wear,longest tool life,and best surface quality.Moreover,in comparisons between cemented-carbide and compacted-graphite cast iron machined under the same conditions,the wear mechanism of the coated tools was found to depend on the cast iron being machined.Therefore,the performance requirements of a tool depend on multiple factors,and selecting an appropriately coated tool for a particular cast iron material is essential.     

不同涂层刀具切削淬硬H13钢加工性能研究

为了研究不同涂层刀具切削淬硬H13钢的切削性能,进行了多层Ti化合物涂层、TiAlN涂层以及MTTiCN厚Al_2O_3TiN涂层材料刀具车削加工淬硬H13钢试验,分析了不同的涂层材料刀具与切削力、切削温度、涂层刀具磨损以及刀具寿命的关系。研究得出:多层Ti化合物涂层刀具受到三个方向的力都大于其它两种涂层的刀具,而且切削温度最高;用TiAlN涂层刀具切削时温度最低;切削过程中三种刀具后刀面磨损程度不同,发现多层Ti化合物涂层刀具磨损最为严重,寿命最短;MT-TiCN厚Al_2O_3Ti N涂层材料刀具比多层Ti化合物涂层刀具寿命长30%;TiAlN涂层刀具的切削寿命最长比多层Ti化合物涂层刀具寿命长45%。     

TiAlN涂层刀具对不同调质状态40Cr钢切削性能研究

为了更好地指导TiAlN涂层刀具在金属切削加工中的应用,采用物理气相沉积法制备了TiAlN涂层刀具,应用TiAlN涂层刀具和未涂层刀具对不同调质状态的40Cr钢进行了干式切削试验。通过对切削过程中切削力和切削温度检测,考察了TiAlN涂层刀具的切削性能。结果表明,与YTl5硬质合金刀具相比,TiAlN涂层刀具适合切削高硬度的金属材料,且优越性更明显。     

TiAlN涂层硬质合金刀具车削钛合金螺纹试验

为研究Ti Al N涂层硬质合金刀具车削钛合金螺纹的切削性能,采用Ti Al N涂层硬质合金螺纹刀片进行试验,得出了在进给量2.4mm/r、背吃刀量0.2mm时的最优切削速度为28m/min。在此条件下,验证了刀片前角较小时主切削力小,散热效率高;而前角较大时,切屑螺旋角小且切削长度较长,断屑效果不佳。当进给方向向左时,后刀面的磨损主要是在左后刀面,磨损相对右后刀面严重,较大的后角使得刀片右后刀面磨损宽度小,涂层剥落宽度也小,寿命更长。     

Comparative evaluation of machinability characteristics of Nimonic C-263 using CVD and PVD coated tools

Machining of Nimonic C-263 has always been a challenging task owing to its hot strength, low thermal conductivity, tendency to work harden and affinity towards tool materials. Although coated tools have been used to overcome some of these challenges, selection of coated tool with appropriate deposition technique is of immense significance. The current study attempts to comparatively evaluate various performance measures in machining of Nimonic C-263 such as surface roughness, cutting force, cutting temperature, chip characteristics, and tool wear with particular emphasis on different modes of tool failure for commercially available inserts with multi-component coating deposited using chemical vapour deposition (CVD) and physical vapour deposition (PVD) techniques. Influence of cutting speed (V_c) and machining duration (t) has also been investigated using both coated tools. The study demonstrated remarkable decrease in surface roughness (74.3%), cutting force (6.3%), temperature (13.4%) and chip reduction coefficient (22%) with PVD coated tool consisting of alternate layers of TiN and TiAlN over its CVD coated counterpart with TiCN/Al₂O₃ coating in bilayer configuration. Severe plastic deformation and chipping of cutting edge and nose, abrasive nose and flank wear along with formation of built-up-layer (BUL) were identified as possible mechanisms of tool failure. PVD coated tool successfully restricted different modes of tool wear for the entire range of cutting speed. Superior performance can be attributed to the hardness and wear resistance properties, thermal stability due to presence of TiAlN phase and excellent toughness owing to PVD technique and multilayer architecture.     

Influence of cutting speed on cutting force,flank temperature,and tool wear in end milling of Ti-6Al-4V alloy

Tool wear is one of the most important problems in cutting titanium alloys due to the high-cutting temperature and strong adhesion. Recently, the high-speed machining process has become a topic of great interest for titanium alloys, not only because it increases material removal rates, but also because it can positively influence the properties of finished workpiece. However, the process may result in the increase of cutting force and cutting temperature which will accelerate tool wear. In this paper, end milling experiments of Ti-6Al-4V alloy were conducted at high speeds using both uncoated and coated carbide tools. The obtained results show that the cutting force increases significantly at higher cutting speed whether the cutter is uncoated carbide or TiN/TiAlN physical vapor deposition (PVD)-coated carbide. For uncoated carbide tools, the mean flank temperature is almost constant at higher cutting speed, and no obvious abrasion wear or fatigue can be observed. However, for TiN/TiAlN PVD-coated carbide tools, the mean flank temperature always increases as the increase of cutting speed, and serious abrasion wear can be observed. In conclusion, the cutting performance of uncoated inserts is relatively better than TiN/TiAlN PVD-coated inserts at a higher cutting speed.     

精密切削过程三维有限元分析

采用有限元方法模拟三维精密切削过程,包括三维正交切削和三维斜角切削。切屑和刀具的摩擦应力采用修正库仑摩擦方程来计算,工件的流动应力是应力、应变、应变率和温度的函数,采用局部网格重划分技术。通过三维切削模拟可以获得在不同刃倾角精密切削过程的条件下切屑形状、切削力和切削温度场的分布情况。仿真结果表明:刃倾角对主切削力和切深抗力影响不大,但对切屑形状、进给抗力和切削温度场分布影响较大。     

基于实验Inconel718正交切削有限元仿真分析

为研究犁削效应和前刀面粘压对Inconel718切削过程的影响.基于正交切削实验建立Inconel718有限元切削模型,模型结果同实验值对比以验证模型可靠性.通过改变刀具圆角半径和负前角参数,提取并比较不同的切削力时域曲线和刀具温度,分析犁削效应和前刀面粘压.研究表明犁削效应提高进给力数值,刀具圆角半径由0变为5μm,Inconel718切削进给力均值提高7％：前刀面粘压提高刀具和切屑温度,有利于切屑分离.但刀具负前角为-20＆#176;,切削加工不稳定.     

硬质合金刀具高速车削钛合金的切削性能研究

采用单因素试验法,用未涂层硬质合金刀具和TiAlN涂层硬质合金刀具对Ti-6Al-4V钛合金进行了高速干车削试验,通过对切削过程中切削力、刀具寿命、切削温度以及加工表面粗糙度的分析,得出了两种刀具高速干车削钛合金的切削性能,为钛合金高速切削刀具的设计提供了试验依据。