高速铣削刀具在高速切削加工中的应用

高速切削加工中,刀具是直接影响加工质量、生产效率和加工成本的重要因素.文章分析和讨论了高速铣削加工中刀具材料、刀具涂层以及刀具的结构参数等对刀具性能的影响;并以一零件加工为例,分析和介绍了高速铣削时其刀具的选用,以及通过刀具提高零件加工精度、表面质量和加工效率的技术方法.     

高速切削加工中刀具材料的合理选择

随着现代制造技术的发展,高速切削已成为先进制造技术中最重要的加工工艺之一,其应用将大幅度地提高加工效率和加工质量,而刀具材料是实现这一工艺的关键,结合国内外研究情况,文章分析了高速切削对刀具材料的要求,以及在高速切削加工中常用的刀具材料的类型和性能,并对常用的被加工材料在高速切削时刀具材料的选择方法进行了阐述.     

薄壁铝合金高速铣削工艺寻优及模拟仿真

本文详细讨论了薄壁零件的加工技术.首先,以CAXA软件为技术平台,自动生成零件的刀具路径,并进行了模拟仿真加工;针对薄壁零件刚性差、强度弱、加工工艺性差、易发生加工变形和切削振动等情况,决定采用高速加工技术.通过对机床、刀具、工件以及切削参数等进行全面分析,采用了刚度大的高速切削机床,并选择了合适的切削刀具.通过改变工件装夹方式,优化编程策略和合理选用切削用量,实现了薄壁零件的高速干式切削.     

高速切削刀具系统的研究与试验分析

通过高速切削试验对切削刀具系统进行研究,特别是对刀具寿命和刀具动平衡的影响因素进行分析,得到切削速度、进给量等对刀具磨损的影响规律曲线以及基于切削用量的刀具耐用度数学预测模型,试验所得数据为高速切削加工切削用量的合理选择,特别是加工参数的优化问题提供了参考。     

刀具材料与工件材料的元素扩散检测研究

高速切削加工已经成为切削加工的主流,但在高速切削加工时,刀具的扩散磨损加剧.由于在实际加工中很难对刀具的扩散磨损进行深入研究,文章采用刀具材料与工件的静态扩散实验装置,利用带能谱分析的扫描电子显微镜,对刀具材料(YG6)和钛合金工件(Ti-6Al-4V)的静态扩散试样进行了分析.分析表明,YG6和Ti-6Al-4V之间确实可以发生元素的相互扩散.分析的结果可以对切削加工过程中刀具的扩散磨损研究提供帮助.     

铍铜合金铣削过程刀具黏附现象对切削颤振影响分析

为了满足高精密铍铜件表面的加工要求,研究刀具表面黏附过程对切削系统和已加工表面的影响,有利于提高加工质量和加工效率。通过建立二自由度切削颤振系统,结合工件材料特性、黏结过程和断续切削过程,采用单因素高速铣削实验方法,解析刀具损伤、切削颤振和已加工表面的内在联系,并通过电镜扫描和白光干涉对刀具表面和已加工表面进行对比分析。切削速度和黏附程度的差异性,极大地影响了切削过程的稳定性,导致已加工表面缺陷的产生。不同黏附环境往往导致了不同的切削状态,尤其是高黏附率环境下的刀具表面黏附有利于维持切削刃形态和减缓加工颤振现象。     

基于间歇性车削加工过程中刀具状态实时检测的研究

针对间歇性切削过程中刀具受间歇性冲击导致的损坏,基于一种新的信号处理方法提出一种用于在线预测刀具切削过程中刀具状态监测方法。该方法基于希尔伯特黄变换(HHT)和Taer-Kaiser能量算符(TKEO),不依赖于切削参数和工件材料对预失效阶段的非稳定裂纹拓展特性进行识别。对刀具状态与切削参数和工件材料参数之间的相关性加以分析并用于保护加工表面。通过实验对监测系统的有效性进行验证,能够保证在刀具损坏之前停止机床操作,验证了该系统的准确性。     

基于遗传算法优化HMM的刀具磨损状态监测研究

对于切削过程中的刀具磨损,采用隐马尔可夫模型(HMM)来识别刀具不同的磨损状态。并且针对隐马尔可夫模型的Baum-Welch算法易陷入局部极小的缺陷,提出一种利用遗传算法优化Baum-Welch算法中B初值的改进方法,从而提高HMM对刀具磨损状态的识别率。通过对切削过程中主轴电机的输出电流信号进行小波包分解提取特征向量,利用Lloyd算法进行量化编码,作为观测序列输入优化的HMM来识别刀具的磨损状态。实验结果表明,该方法能够准确有效地进行铣刀磨损状态监测。     

浅谈高速切削加工技术

阐述了高速切削在未来制造技术中的重要性,对高速切削的定义、意义、原理进行了诠释,分析了高速切削加工中机床的选择、刀具的材料、加工的工艺、编程的方法,最后通过在模具加工中的应用论证了高速切削的优势。     

基于切削参数的高速铣削系统稳定性研究

切削中的振动对加工质量有很大的影响,通过高速铣削试验及仿真分析,对基于工艺参数和刀具参数的高速铣削系统稳定性进行研究,得到了主轴转速、进给量、切削深度、刀具几何参数等对切削颤振系统稳定性的影响规律。试验所得结果为高速铣削加工切削用量的合理选择,特别是加工参数的优化提供了参考。     

High-speed milling of titanium alloys using binderless CBN tools

The performance of conventional tools is poor when used to machine titanium alloys. In this paper, a new tool material, which is binderless cubic boron nitride (BCBN), is used for high-speed milling of a widely used titanium alloy Ti–6Al–4V. The performance and the wear mechanism of the BCBN tool have been investigated when slot milling the titanium alloy in terms of cutting forces, tool life and wear mechanism. This type of tool manifests longer tool life at high cutting speeds. Observations based on the SEM and EDX suggest that adhesion of workpiece and attrition are the main wear mechanisms of the BCBN tool when used in high-speed milling of Ti–6Al–4V.     

Modeling and identification of tool holder–spindle interface dynamics

The majority of the chatter vibrations in high-speed milling originate due to flexible connections at the tool holder–spindle, and tool–tool holder interfaces. This article presents modeling of contact stiffness and damping at the tool holder and spindle interface. The holder–spindle taper contact is modeled by uniformly distributed translational and rotational springs. The springs are identified by minimizing the error between the experimentally measured and estimated frequency response of the spindle assembly. The paper also presents identification of the spindle's dynamic response with a holder interface, and its receptance coupling with the holder–tool stick out which is modeled by Timoshenko beam elements. The proposed methods allow prediction of frequency-response functions at the tool tip by receptance coupling of tools and holders to the spindle, as well as analyzing the influence of relative wear at the contact by removing discrete contact springs between the holder and spindle. The techniques are experimentally illustrated and their practical use in high speed milling applications is elaborated.     

Tool life and tool wear in the semi-finish milling of inclined surfaces

Functional die and mold components have complex geometries and are made of high hardness materials, which make them difficult to machine. This work contributes to a better understanding of this type of process and of the wear mechanisms of tools used in semi-finishing operations of hardened steels for dies and molds. Several milling experiments were carried out to cut AISI H13 steel with 50 HR_C of hardness using the high-speed milling technique. The main goal was to verify the influence of workpiece surface inclination and cutting conditions on tool life and tool wear mechanisms. The main conclusions were the inclination of the machined surface strongly influences tool life and tool wear involves different mechanisms. At the beginning of tool life, the wear was caused mainly by abrasion on the flank face plus diffusion and attrition on the rake face. At the end of tool life, the mechanisms were adhesions and microchipping at the cutting edge.     

Effect of coolant strategy on tool performance, chip morphology and surface quality during high-speed machining of A356 aluminum alloy

This paper describes the results of application of different coolant strategies to high-speed milling of aluminum alloy A356 for automotive industry. The paper investigates the effect of flood coolant, dry cutting, and minimum quantity of lubricant (MQL) technologies on tool wear, surface roughness and cutting forces. The cutting speed range was up to 5225 m/min. The feed rate used was up to 20 m/min. The result of MQL application is compared with dry milling and milling with flood coolant application. It was found that the MQL technology could be a viable alternative to the flood coolant application. The adhesive tool wear mechanism and adhesion activated surface quality deterioration are revealed and the role of lubricant in their reduction is defined.     

涂层硬质合金力高速铣削Crl2模具钢的破损失效分析

研究涂层硬质合金刀具在高速铣削淬硬模具钢Cr12过程中刀具超常磨损、破损的原因,分析刀具耐用度的影响因素,并通过扫描电镜和能谱分析的方法对刀具的磨损、破损的机理进行研究,找出刀具破损的主要原因.     

碳纤维/树脂基复合材料高速铣削的刀具磨损机理

采用涂层(Ti CN,Ti Al N)与无涂层超细晶粒硬质合金立铣刀对碳纤维/树脂基复合材料进行高速铣削试验,研究了刀具后刀面磨损带扩展及刀具磨损规律,并探讨了切削力、毛刺随着刀具磨损的变化趋势,观察了刀具的微观磨损形貌,分析了刀具的磨损机理。结果表明:在相同的切削条件下,无涂层刀具的后刀面磨损量及切削力最大,毛刺扩展严重,后刀面主要发生磨粒磨损,由于黏着磨损和氧化磨损对切削刃的弱化作用,主切削刃发生了微崩刃;Ti CN涂层刀具后刀面主要发生磨粒磨损,并伴随有黏着磨损和轻微的氧化磨损,失效形式为剥落和微崩刃;Ti Al N涂层刀具的后刀面磨损量及切削力最小,毛刺扩展缓慢,更适合碳纤维复合材料的加工。其后刀面主要发生了磨粒磨损,其失效形式为剥落。     

基于改进LSTM-AdaBoost的铣刀磨损量预测

针对铣刀磨损量预测时精度低的问题,提出一种基于黑寡妇算法（BWO）优化的长短期记忆神经网络（LSTM）与AdaBoost集成学习算法相结合的铣刀磨损量预测方法。在铣刀磨损振动信号中提取时域、频域以及时频域多域特征。通过BWO算法优化LSTM的核心参数,并将优化后的LSTM网络与AdaBoost算法进行结合,构建铣刀磨损量预测模型。最后用PHM Society 2010铣刀全寿命周期的振动数据进行实验。研究结果表明：所提方法能够有效地预测出铣刀磨损量变化值,优化后模型的平均绝对误差百分比为3.436%、均方根误差为6.471、决定系数 R2 为0.935。该方法能够获得准确率更高的铣刀磨损量预测值,预测效率更高。     

High-speed five-axis milling of hardened tool steel

This paper investigates critical issues related to high-speed five-axis milling of hardened D2 tool steel (hardness HRc 63). A forging die cavity was designed to represent the typical features in dies and molds and to simulate several effects resulting from complex tool path generation. Cutting tool materials used were coated carbide for the roughing and semi-finishing processes and polycrystalline cubic boron nitride (PCBN) for the finishing process. The effects of complex tool paths on several critical machining issues such as chip morphology, cutting forces, tool wear mechanisms, tool life and surface integrity were also investigated. The main tool failure mode was chipping due to the machine tool dynamics. A five-axis analytical force model that includes the cutter location (CL) data file for computing the chip load has been developed. The effect of instantaneous tilt angle variation on the forces was also included. Verification of the force model has been performed and adopted as a basis for explaining the difficulties involved with high-speed five-axis milling of D2 tool steel.     

The influence of tool flank wear on residual stresses induced by milling aluminum alloy

The machining processes could induce residual stresses that enhance or impair greatly the performance of the machined component. Machining residual stresses correlate very closely with the cutting parameters and the tool geometries. In this paper, the effect of the tool flank wear on residual stresses profiles in milling of aluminum alloy 7050-T7451 was investigated. In the experiments, the residual stresses on the surface of the workpiece and in-depth were measured by using X-ray diffraction technique in combination with electro-polishing technique. In order to correlate the residual stresses with the thermal and mechanical phenomena developed during milling, the orthogonal components of the cutting forces were measured using a Kistler 9257A type three-component piezoelectric dynamometer. The temperature field of the machined workpiece surface was obtained with the combination of infrared thermal imaging system and finite element method. The results show that the tool flank wear has a significant effect on residual stresses profiles, especially superficial residual stress. As the tool flank wear length increases, the residual stress on the machined surface shifts obviously to tensile range, the residual compressive stress beneath the machined surface increases and the thickness of the residual stresses layer also increases. The magnitude and distributions of the residual stresses are closely correlated with cutting forces and temperature field. The three orthogonal components of the peak cutting forces increase and the highest temperature of the machined workpiece surface also increases significantly with an increase in the flank wear. The results reveal that the thermal load plays a significant role in the formation of the superficial residual stress, while the dominative factor that affects thickness of residual stresses layer is the mechanical load in high-speed milling aluminum alloy using worn tool.     

Cutting characteristics of PVD-coated tools deposited by filtered arc deposition (FAD) method

The cutting characteristics of novel physical vapor deposition (PVD)-coated tools deposited using filtered arc deposition (FAD) method are investigated. The TiCN-coated films are extremely smooth without any droplets. They exhibit superior hardness and adherence and a favorable cutting performance for the high-speed milling of a prehardened stainless steel. The availability of a newly proposed VN film is also examined. Owing to the good lubrication and tribological properties of the VN coating film, the lower cutting force, flank wear with, and cutting temperature than those of the TiN-coated tool are obtained in milling of the prehardened steel.