基于ABAQUS有限元仿真的硬质合金刀具磨损机制研究

钛合金在切削过程中会产生严重的加工硬化现象,导致切削性下降、刀具磨损加剧,直接影响工件的加工质量。为研究钛合金切削性能和刀具磨损机制,利用ABAQUS软件建立了钛合金的有限元模型,对其切削过程进行仿真分析,研究硬质合金刀具磨损机制;设计Ti6Al4V钛合金车削实验,研究不同加工参数对刀具磨损程度的影响规律。研究结果表明:在切削钛合金时,刀具的磨损主要发生在刀尖和后刀面位置,刀具的磨损长度随车削速度的增加而变大,随车削深度的增加而减小,随进给量的增加呈现出先减小后变大的情况,实验和仿真结果趋于一致,平均误差在6%以内。     

钛合金芯轴车削加工工艺的改进

以某钛合金芯轴为研究对象,通过分析钛合金芯轴的加工难点及原工艺的缺点,提出了改进工艺,经多次钛合金车削加工试验,通过合理选择刀具材料、刀具几何参数并优化切削参数,保证了钛合金芯轴加工质量、减小了车削变形、刀具磨损。实践表明,加工钛合金使用的刀具材料应少钛或无钛元素,优选YG类硬质合金。刀具后角要大些,刀尖圆弧半径不易过大。粗车时,保证必要的刀具耐用度,确定切削速度;精车时,尽量采用高速切削,可降低表面粗糙度。该研究为细长轴类钛合金加工提供了可靠依据,具有一定的应用推广价值。     

钛合金TC4高效粗加工工艺的研究

本文通过分析钛合金TC4的切削性能特点,选择不同几何结构的硬质合金刀具进行高效粗车加工实验,探索最大金属去除量的切削参数,分析TC4高效车削刀具磨损机理,优选刀具结构。结果显示,与切深相比,刀具寿命对切削速度更为敏感;适当降低切削速度而提高切深可有效提高金属去除量,在实验切削参数条件下,选择切削速度v=60 m/min,进给量f=0.3 mm/r,切深ap=4 mm更有利于钛合金TC4的高效粗车加工,单个刀尖金属去除量最大;刀片前刀面的"小突起"或者"小筋条"结构可有效抑制前刀面的月牙洼磨损和粘结磨损;钛合金TC4高效粗加工刀刃要求具有一定的锋利性和刃口强度,-T槽型刀片的前角结构更有利于TC4的高效车削加工。     

车削DT4E纯铁刀具材料适配性研究

针对纯铁切削过程中粘刀、刀具磨损快等问题,进行了纯铁和刀具材料的适配性试验,分别使用硬质合金刀具HTI10、涂层刀具VP15TF和金属陶瓷刀具NX3035车削电工纯铁DT4E工件,在车削过程中测量刀具磨损量,使用能谱分析(EDS)和扫描电子显微镜(SEM)研究刀具磨损机理,分析刀具磨损对切削性能的影响。结果表明:金属陶瓷刀具NX3035更适合纯铁的切削加工,刀具磨损最小、切削力最平稳,能获得最好的已加工表面质量;刀具在纯铁切削中的主要磨损形式为后刀面均匀磨损和V型沟槽磨损,主要磨损机理为高温下的粘结磨损、扩散磨损和氧化磨损的综合作用。     

硬质合金刀具车削Ti6Al4V钛合金试验研究

文章采用单因素试验法,用未涂层硬质合金刀具和TiAlN涂层硬质合金刀具对Ti6Al4V钛合金进行了车削试验,通过对切削过程中刀具寿命、切削力、切削温度以及加工表面粗糙度的分析,得出了两种刀具车削钛合金的切削性能,为钛合金车削试验提供了依据.     

基于Fitnet的刀具磨损量预测方法研究

针对切削难加工材料时刀具磨损对加工质量的影响,通过实验研究PCBN刀具切削硬质合金YG10材料的刀具磨损机制,在一定的切削参数条件下,利用Fitnet神经网络预测刀具磨损规律,获得较好的磨损量预测精度,为刀具加工补偿提供了理论依据。     

基于刀具磨损率及加工效率的工艺参数优化

钛合金环槽铆钉因其高的铆接强度及良好的防松性能被广泛应用于航空航天行业。钛合金切削性能差,切槽刀具工作环境恶劣,使得切槽车刀的磨损更加严重。以钛合金环槽车削加工为研究对象,运用数值方法,得到不同的切削速度、进给量参数下,钛合金车削加工环槽时硬质合金刀具后刀面的磨损速率。通过数据分析,建立刀具后刀面磨损速率预测模型,利用最小二乘法进行参数辨识。应用遗传算法对考虑刀具后刀面磨损速率和切削加工效率的双目标进行优化,得到最优工艺参数组合。结果表明,经过优化的工艺参数,使整体目标值提高了2.9%。     

基于响应曲面法的钛合金干式车削工艺参数优化

为了提高钛合金干式车削加工质量,采用响应曲面法对主要车削工艺参数进行了优化,以工件表面粗糙度Ra和刀具磨损量VC作为评价指标,设计了切削速度、背吃刀量和进给量三因素的Box-Behnken实验模型。利用方差和拟合残差概率分布分析三因素的显著性及交互作用,并结合实验检验所建表面粗糙度和刀具磨损二阶响应预测模型的有效性。响应曲面法优化后的最佳工艺参数为:切削速度20 m/min、背吃刀量0.1788 mm、进给量0.1 mm/r,此时得到的表面粗糙度和刀具磨损量为1.031μm和155.6μm,与预测值的误差分别为:9.93%和1.58%。结果表明:基于响应曲面法的钛合金干式车削表面粗糙度和刀具磨损量预测模型准确有效。     

钛合金TC21车削过程的三维数值建模与试验研究

针对一种新型高强度钛合金材料TC21钛合金难加工的特点,建立了车削过程的三维有限元模型。采用建立的三维车削有限元模型对钛合金材料TC21的切屑成形过程进行了数值模拟,并获得了切削过程的切削力变化曲线及应力值等物理量。同时,通过钛合金TC21的车削试验研究了刀具前角、进给速度及主轴转速对切削过程的影响规律。在相同切削条件下对试验结果与数值模拟进行了对比,结果验证了数值模拟的可靠性。实验结果表明,钛合金材料TC21的切屑也是锯齿状,且随着刀具前角的减小,TC21材料切屑锯齿状形态越明显。     

刀具涂层和几何参数对钻削SiC/SiC的影响

为了研究SiC/SiC复合材料的加工性和在钻削过程中的切削力、刀具磨损和孔质量,使用整体硬质合金钻头和金刚石涂层的硬质合金钻头对SiC/SiC复合材料进行钻削试验,并设计正交试验对刀具的几何角度参数和钻削过程中的的切削力的关系进行分析,加工后观察刀具磨损和孔出口质量。结果表明:在低转速低进给条件下,金刚石涂层的硬质合金钻头适合加工SiC/SiC复合材料。在加工参数不变的条件下,对切削力影响最大的角度因素为螺旋角,其次是顶角,后角影响最小,并根据正交试验的结果得出一组最优刀具角度参数:顶角118°,螺旋角20°,后角16°。刀具的主要磨损形式是涂层脱落,孔出口缺陷的主要形式是毛刺和纤维拔出。     

车-铣组合切削在钛合金加工中的应用研究

针对钛合金产品加工困难的问题,通过分析钛合金的切削加工性能,分别从刀具材料、刀具角度、切削用量及切削液等方面论述了钛合金产品车削加工工艺的优化策略,提出了采用楔形刀具和车-铣组合切削方式改善钛合金切削加工条件和提高加工效率的新思路,解决了传统切削加工钛合金产品的技术难题,对进一步研究钛合金的切削加工工艺具有一定的参考价值和生产指导意义。     

Tool flank wear prediction in CNC turning of 7075 AL alloy SiC composite

Flank wear occurs on the relief face of the tool and the life of a tool used in a machining process depends upon the amount of flank wear; so predicting of flank wear is an important requirement for higher productivity and product quality. In the present work, the effects of feed, depth of cut and cutting speed on flank wear of tungsten carbide and polycrystalline diamond (PCD) inserts in CNC turning of 7075 AL alloy with 10 wt% SiC composite are studied; also artificial neural network (ANN) and co-active neuro fuzzy inference system (CANFIS) are used to predict the flank wear of tungsten carbide and PCD inserts. The feed, depth of cut and cutting speed are selected as the input variables and artificial neural network and co-active neuro fuzzy inference system model are designed with two output variables. The comparison between the results of the presented models shows that the artificial neural network with the average relative prediction error of 1.03% for flank wear values of tungsten carbide inserts and 1.7% for flank wear values of PCD inserts is more accurate and can be utilized effectively for the prediction of flank wear in CNC turning of 7075 AL alloy SiC composite. It is also found that the tungsten carbide insert flank wear can be predicted with less error than PCD flank wear insert using ANN. With Regard to the effect of the cutting parameters on the flank wear, it is found that the increase of the feed, depth of cut and cutting speed increases the flank wear. Also the feed and depth of cut are the most effective parameters on the flank wear and the cutting speed has lesser effect.     

激光熔覆碳化钛增强钛基复合涂层研究进展

钛合金具有密度低、比强度高、耐腐蚀性强等显著优点,在航空航天、海洋工程等领域具有广阔的应用前景。然而,钛合金硬度低、耐磨性差,严重制约其在摩擦工况下的使用寿命。激光熔覆技术具有生产效率高、热影响区窄、结合强度高、组织致密等优势,被广泛用于钛合金零部件表面改性和熔覆修复。高硬、高模量碳化钛的热物性参数与钛合金基材相近,常被选作激光熔覆钛基复合涂层的增强相,以提高其耐磨性。介绍了碳化钛的晶体结构、生长形态和性能特点。综述了碳化钛增强钛基激光熔覆材料体系以及工艺参数对熔覆层成形质量、宏观形貌和微观组织的影响。重点从碳化钛增强相的分布、数量、尺度以及相结构等方面,论述了碳化钛增强钛基激光熔覆层的组织特征,同时阐述了碳化钛强化机制,讨论了碳化钛增强钛基激光熔覆层组织特征与耐磨性能的内在关联性。最后提出了目前激光熔覆碳化钛增强钛基复合涂层研究中存在的问题与展望。     

Machinability of hypereutectic silicon-aluminum alloys

The machinability of high-silicon aluminum alloys made by a P/M process and by casting was compared. The cutting test was conducted by turning on lathes with the use of cemented carbide tools. The tool wear by machining the P/M alloy was far smaller than the tool wear by machining the cast alloy. The roughness of the machined surface of the P/M alloy is far better than that of the cast alloy, and the turning speed did not affect it greatly at higher speeds. The P/M alloy produced long chips, so the disposal can cause trouble. The size effect of silicon grains on the machinability is discussed.     

钛合金切削用磷酸酯类添加剂润滑特性及有机碱复配研究

目的 提高水基润滑液对钛合金的润滑抗磨性能。方法 针对钛合金/硬质合金摩擦副,使用SRV往复式球盘摩擦磨损实验机,测试了常用的三种切削液及四种水溶性磷酸酯溶液的摩擦磨损效果。通过三维白光干涉形貌仪与扫描电子显微镜对磨损表面形貌及磨痕内外能谱进行检测,分析磨损机理及润滑性能,探究对钛合金具有高效润滑作用的水溶性添加剂,并通过有机碱调节溶液的pH,复配适用于钛合金的润滑体系。结果 对铝合金具有很好润滑作用的切削油对钛合金润滑效果很差,而所选水基润滑液效果较好。研究发现,四种水溶性磷酸酯溶液在质量分数为2%时即可对钛合金产生较好的润滑效果,其中,脂肪醇醚磷酸酯（MOA-3P）润滑效果最突出,摩擦系数最低（0.15）,且稳定、粘着磨损最少。通过二甘醇胺及三乙醇胺调节磷酸酯溶液pH至碱性,除支链烷基化磷酸酯（CP-NF-3）溶液外,其他溶液的摩擦系数均有所变大,且波动性增强,而CP-NF-3磷酸酯碱性溶液润滑时,摩擦系数变化很小,稳定在0.2左右。结论 水溶性磷酸酯与适当的有机碱复配的润滑液,可实现对钛合金的良好润滑,用于钛合金水基切削液体系的研发。     

Effect of chamfer angle on wear of PCBN cutting tool

In precision hard turning, a remaining problem is to minimise tool wear to maintain the accuracy of geometry and surface finish. Tool wear not only directly reduces the part geometry accuracy but also increases cutting forces drastically. The change in the cutting forces also causes instability in the tool motion, which results in more inaccuracy. PCBN cutting tools are often used in hard turning. However, they are still relatively expensive compared to ordinary carbide cutting tools. In order to attain sufficiently high production rates at minimum cost, increase of knowledge on cutting tool geometry is necessary. This article presents a study of the effect of chamfer angle on tool wear of PCBN cutting tool in the super finishing hard turning. The correlation between cutting force, tool wear and tool life were investigated. The optimised chamfer angle for PCBN cutting tool is suggested. Finally, the distribution of stresses and maximum principal stress working on the tool edge were calculated with the use of finite element method.     

Experimental and numerical studies on the performance of alloyed carbide tool in dry milling of aerospace material

Titanium alloy is widely used in the aerospace industry for applications requiring high strength at elevated temperature and high mechanical resistance. The difficulty of dislocation motion through the microstructure is responsible for its high yield strength. However, the main problems encountered when machining titanium alloy are the low material removal rate and the short tool life.This study investigated the suitability of uncoated cemented carbide tools in ball-end milling of the aerospace titanium alloy Ti-6242S. The experiments were carried out under dry cutting condition. Cutting speeds in the range of 60–150 m/min were considered. The axial and radial depths of cut were kept constant at 2.0 and 8.8 mm, respectively, and the feed rate values of 0.1 and 0.15 mm/tooth were selected. SEM analysis has been carried out on the worn tools and shows that flank wear and excessive chipping on the flank edge are the main tool failure modes. For both feed rates, the results demonstrate that the higher the cutting speed the better is the surface finish. The FEM simulation provides good results on modelling of chip formation and can be helpful to calculate the contact parameters and to understand the tool wear mechanisms when dry machining aerospace titanium alloys.     

基于纳米流体冷却的钛合金车削温度场分析

车削钛合金时加工区温度高,会降低工件表面质量、加剧金刚石车刀磨损。可使用雾化纳米流体喷射等冷却方式改善车削环境,提高钛合金表面的加工质量和金刚石刀具的耐用度。基于ABAQUS仿真软件建立Ti-6Al-4V钛合金材料模型,研究不同冷却方式下切屑和刀具的温度变化规律,并进行钛合金车削试验对仿真结果进行验证。结果表明:车削钛合金时使用雾化纳米流体喷射方式降温效果良好,切屑和刀具表面最高温度分别为168 ℃和142 ℃,相比于普通冷却方式的温度下降了约70%。在稳定切削状态下的切屑和刀具温度仿真和试验结果误差在5%以内,仿真结果合理。