Wear Patterns and Mechanisms of Cutting Tools in High Speed Face Milling

High speed machining has received an important interest because it leads to an increase of productivity and a better workpiece surface quality. However, at high cutting speeds, the tool wear increases dramatically due to the high temperature at the tool-workpiece interface. Tool wear impairs the surface finish and hence the tool life is reduced. That is why an important objective of metal cutting research has been the assessment of tool wear patterns and mechanisms. In this paper, wear performances of PCBN tool, ceramic tool, coated carbide tool and fine-grained carbide tool in high speed face milling were presented when cutting cast iron, 45# tempered carbon steel and 45# hardened carbon steel. Tool wear patterns were examined through a tool-making microscope. The research results showed that tool wear types differed in various matching of materials between cutting tool and workpiece. The dominant wear patterns observed were rake face wear, flank wear, chipping, fracture and breakage. The main wear mechanisms were mechanical friction, adhesion, diffusion and chemical wear promoted by cutting forces and high cutting temperature. Hence, the important considerations of high speed cutting tool materials are high heat-resistance and wear-resistance, chemical stability as well as resistance to failure of coatings. The research results will be great benefit to the design and the selection of tool materials and control of tool wear in high-speed machining processes.

Chip formation in high speed milling of Ti-6Al-4V alloy under nitrogen-oil-mist

High speed milling experiments using nitrogen-oil-mist as the cutting medium were carried out to investigate the characteristics of chip formation for Ti-6Al-4V alloy.Within the range of conditions employed(cutting speed,vc=190-300 m/min;cutting depth of axial,ap=5,7 mm),saw-tooth chips were produced in these experiments.During the macro and micro analysis of the Ti-6Al-4V chips,an optical microscope and a scanning electron microscope(SEM)were used to study the microstructure and the morphology of the chips,and the X-ray photoelectron spectroscopy(XPS)was employed for chemical analysis.Comparisons were made to study the influence of different cutting media(nitrogen-oil-mist,air-oil-mist and dry cutting condition)on chip formation.Results indicate that cutting media have significant effects on chip formation.Nitrogen-oil-mist is more suitable for improving the contact condition at chip-tool interface and increasing the tool life in high speed milling of Ti-6Al-4V alloy than air-oil-mist and dry cutting.

基于PowerMILL Vortex旋风铣与MachineDNA系统应用研究

旋风铣Vortex是Delcam最新的高速区域清除加工策略,可用于2轴、3轴、定位五轴以及残留加工。和传统高速加工方法相比,可节省多达60%的加工时间。Machine DNA是Delcam的一项最新专利技术,它可捕捉单个机床的运行特点和数据,并使用捕捉的数据来完善Power MILL产生的刀具路径[1]。旋风铣Vortex与Machine DNA的结合使粗加工效率提升的同时,最大限度地发挥机床潜能,从而可在合理安全的切削条件下实现加工效率最大化。

Engagement Angle Modeling for Multiple-circle Continuous Machining and Its Application in the Pocket Machining

The progressive cutting based on auxiliary paths is an effective machining method for the material accumulating region inside the mould pocket. But the method is commonly based on the radial depth of cut as the control parameter, further more there is no more appropriate adjustment and control approach. The end-users often fall to set the parameter correctly, which leads to excessive tool load in the process of actual machining. In order to make more reasonable control of the machining load and toolpath, an engagement angle modeling method for multiplecircle continuous machining is presented. The distribution mode of multiple circles, dynamic changing process of engagement angle, extreme and average value of engage- ment angle are carefully considered. Based on the engagement angle model, numerous application techniques for mould pocket machining are presented, involving the calculation of the milling force in multiple-circle continuous machining, and rough and finish machining path planning and load control for the material accumulating region inside the pocket, and other aspects. Simulation and actual machining experiments show that the engagement angle modeling method for multiple-circle continuous machining is correct and reliable, and the related numerous application techniques for pocket machining are feasible and effective. The proposed research contributes to the analysis and control tool load effectively and tool-path planning reasonably for the material accumulating region inside the mould pocket.

Design and Performance Analysis of Small Denture Machining Equipment

The research and application on small denture machining equipment are great breakthrough for modern dental restoration technology. In this paper, a small denture machining equipment made of two spindles with four-axis was designed based on machining characteristics and functional analysis. Position accuracy and re-position accuracy were measured by accuracy instrument. In order to test its machining capacity, some typical microstcucture parts, such as straight channel, hemispherical surface, and molars coronal, were selected for high speed milling. It was obtained that the denture machining equipment met the machining requirements with high quality and efficiency, according to the acquisition and analysis of form and position errors, surface roughness, and 3-D profile.

Compound machining of silicon carbide ceramics by high speed end electrical discharge milling and mechanical grinding

A compound process that integrates end electrical discharge (ED) milling and mechanical grinding to machine silicon carbide (SiC) ceramics is developed in this paper. The process employs a turntable with several uniformly-distributed cylindrical copper electrodes and abrasive sticks as the tool, and uses a water-based emulsion as the machining fluid. End electrical discharge milling and mechanical grinding happen alternately and are mutually beneficial, so the process is able to effectively machine a large surface area on SiC ceramic with a good surface quality. The machining principle and characteristics of the technique are introduced. The effects of polarity, pulse duration, pulse interval, open-circuit voltage, discharge current, diamond grit size, emulsion concentration, emulsion flux, milling depth and tool stick number on performance parameters such as the material removal rate, tool wear ratio, and surface roughness have been investigated. In addition, the microstructure of the machined surface under different machining conditions is examined with a scanning electron microscope and an energy dispersive spectrometer. The SiC ceramic was mainly removed by end ED milling during the initial rough machining mode, whereas it is mainly removed by mechanical grinding during the later finer machining mode; moreover, the tool material can transfer to the workpiece surface during the compound process.

高速铣削-激光切割机床数控加工高精度控制技术

激光切割机铣削过程中会因工件变形导致表面出现凹凸不平或波浪状,表面局部区域高低不等,致使机床的浮动轴偏离实际运动轨迹,影响工件铣削加工的质量。为此,提出一种高速铣削-激光切割机床数控加工高精度控制技术。采用运动学理论、矩阵转换函数建立激光切割机床运动数学模型,利用PLC控制器、伺服驱动器及电机等搭建激光切割机床高速铣削加工控制模型,使用负反馈控制算法、位移误差函数控制机床铣削加工浮动轴运动,即当浮动轴执行上浮或者下浮运动时,若浮动轴运动轨迹偏离预设轨迹,调节PLC控制器参数来驱动电机控制作业,使其反向运动,直到落在预设轨迹上,实现铣削加工的高精度控制。实验结果表明,所提技术工件的铣削加工质量高,高速铣削过程中上浮点、下浮点控制误差最大值分别为6 mm、6 mm,铣削加工控制的响应时间为6.8 ms。

基于粉碎齿刀具的吸波蜂窝高速铣削加工试验研究

针对某一典型吸波蜂窝材料,采用粉碎齿刀具在不同切削参数下进行高速铣削试验,从切削力、加工表面质量、切削功率、切削温度等角度分析铣削参数对加工过程参量的影响规律,进而确定吸波蜂窝高速铣削的优化工艺参数。研究表明,提高切削速度有利于降低切削力和改善表面加工质量,当进给速度、切削深度或切削宽度增大时,因单位时间内材料切除体积增大,导致切削力和切削温度升高,造成表面缺陷加剧。以抑制毛刺缺陷形成为主要目标时,综合考虑工艺参数对切削力、切削功率和切削温度的影响,推荐优化工艺参数为主轴转速16000 r·min^(-1)、进给速度4000 mm·min^(-1)、切削深度10 mm和切削宽度15 mm。研究结果可为粉碎齿刀具高速铣削吸波蜂窝材料的工艺优化提供数据参考。

基于五轴平台的枞树型轮槽铣刀加工工艺分析

轮槽成型铣刀是加工汽轮机轮毂槽的重要工具,其结构复杂且加工困难。为提高加工效率和精度,以某型高速钢轮槽铣刀为例,提出基于五轴平台的加工工艺方法。使用UG软件基于五轴车铣复合机床规划粗加工刀具路径,并采用专用后置处理器生成数控加工程序,通过虚拟机床进行仿真验证;采用NUMROTO软件规划精加工路径,获得磨削NC代码并进行虚拟加工验证;进行实际切削验证,通过DOOSAN PUMA SMX2600ST车铣复合加工中心对刀具进行粗加工后,在SAACKE UWIF五轴工具磨床上完成刀具的精加工。实验结果证明,该工艺方法不仅能保证产品质量符合工艺设计要求,而且制造效率提高了20%。

基于GWO-ELM的高速铣削力预测模型研究

针对TC4钛合金、7574铝合金、AISI304不锈钢及45#钢等宇航材料在高速铣削过程中的高速铣削力预测问题,引入基于灰狼算法(GWO)改进的极限学习机(ELM)模型构建高速铣削力预测模型,利用二阶多元回归模型分析确定隐含层节点数,预测结果与BP、RBF、ELM等七种预测模型和实验结果进行比较。研究结果表明:基于GWO-ELM的高速铣削力预测模型隐含层节点数可以利用二阶多元回归模型分析确定,预测模型的准确率为98.8%、决定系数达到0.98871优于其他预测模型,故基于GWO-ELM的高速铣削力预测模型具有可行性和准确性,该研究结果可为GWO-ELM模型隐含层节点数的确定及高速铣削力预测模型的选择提供参考与借鉴。

MASTER CAM动态铣削在数控铣削中的应用研究

该文针对数控铣开粗效率较低,如何提高数控铣开粗效率,降低生产成本进行研究。经过多次试验实践比较,采用MASTER CAM动态铣削方法,通过对其加工方式方法、参数优化等分析研究与应用,得到使用动态铣削加工的方法。MASTER CAM动态铣削方法可以大幅提高加工效率,解决因铣削过程中切深较大,导致主切削力增加,切削温度升高,使刀具损坏或工件变形的情况发生,同时延长刀具使用寿命。此方法在保证零件加工精度的同时,正真做到高速、高效、高精的“三高”实践。操作简单,可充分发挥机床、刀具等性能,进一步为企业节约生产成本,扩大盈利,值得全面推广和借鉴,为数控铣高速、高效加工提供一定的参考依据。

高速铣削中切削力的研究

在高速铣削试验的基础上 ,研究高速切削时切削速度对切削力的影响。结果表明 ,在切削速度较低的情况下 ,切削力随切削转速的增加而增大 ,但达到某一临界速度后 ,随着切削速度继续增大 ,剪切角增大 ,造成切向切削分力下降。

(Ti,Al)N涂层硬质合金刀具高速铣削30CrNi4MoV钢时的磨损机理

使用(Ti,Al)N涂层硬质合金刀具,对难加工材料中的超高强度合金钢(硬度>50HRc、抗拉强度σb>1.6GPa)在切削速度118～236m/min范围内,进行了干式高速端面铣削系统试验。借助能谱探针与电子扫描显微镜(SEM)等工具,选择刀具寿命作为刀具切削性能的评价指标,对硬质合金刀具前、后刀面的磨损形态、磨损机理以及刀具的切削性能进行了分析与研究。研究结果表明,高速切削超高强度合金钢条件下,(Ti,Al)N涂层刀具的失效形式为:前、后刀面磨损失效和发生在主切削刃上的涂层脱落和微崩刃,其主要磨损机理为高温条件下粘结磨损、氧化磨损和扩散磨损的综合作用。

基于变形控制的薄壁结构件高速铣削参数选择

首先对国内外有关研究薄壁件铣削加工变形的文献进行了回顾。然后,对不同切削参数下铣削力变化规律以及因铣削力引起的加工变形进行了理论分析与试验研究,并以此为基础提出了薄壁件高速铣削切削参数选择原则。试验结果表明,采用优化的切削参数不仅使薄壁件加工精度得到了保证,加工效率也大大提高。

氮气油雾介质下Ti-6Al-4V钛合金高速铣削试验研究

通过以氮气油雾作为切削介质的切削方法,应用硬质合金刀具对T i-6A l-4V钛合金材料进行了高速铣削试验,分析了铣削过程中的切屑形成、刀具磨损、已加工表面粗糙度等因素的变化。对氮气油雾介质下的钛合金高速铣削机理进行了探讨,同时通过氮气油雾介质、空气油雾介质以及干切削状况下的钛合金高速铣削对比试验,证明了以氮气油雾为切削介质进行钛合金高速铣削的可行性。研究结果表明,与空气油雾介质及干切削相比,氮气油雾介质下的钛合金切屑表面较为平整,刀具磨损与已加工表面粗糙度均相对较低。利用氮气油雾作为切削介质,是实现钛合金绿色高速切削加工的有效方法。

平底立铣刀高速铣削切削力解析建模

在高速铣削过程中,切削力对刀具的寿命具有重要影响,因此切削力的预测显得尤为重要。首先按照斜角切削模型,将平底立铣刀侧刃沿轴向进行微分,基于铣刀真实切削刃轨迹,计算出单齿瞬时切削厚度,并以角度积分确定积分限的方法建立了侧刃的切削力模型。然后根据直角切削模型,将横刃沿垂直切削刃方向上微分,计算得到微元切削力,通过积分法建立了横刃切削力模型。合并二者建立切削合力模型。最后将切削力解析模型通过Matlab程序化,获得不同切削参数下的切削力仿真曲线。仿真结果表明:解析切削力曲线与实测切削力曲线吻合较好,仿真值与实测值的最大误差为7.14%。

高速侧铣镍基合金Inconel 718切削力试验研究

采用整体式涂层硬质合金立铣刀对镍基合金Inconel 718进行了高速侧铣试验,研究了切削参数(包括切削速度、进给量、轴向切深和径向切深)的变化对切削力的影响。研究发现,随着轴向切深的增大,切削力先增大后减小,这主要是由于刀具在切削力的作用下产生了一定程度的弯曲变形和扭转变形,改变了刀具的整体刚度;随着切削速度、每齿进给量和径向切深的增大,切削力的值呈现线性增加的趋势,其中对切削力变化影响最大的是切削速度。

航空铝合金薄壁件高速铣削受力变形的试验研究

试验研究了高速铣削航空铝合金薄壁件侧壁时切削力随铣削工艺参数变化的规律,给出了薄壁件侧壁高速铣削加工变形随铣削工艺参数变化的规律.在此基础上,应用ANSYS软件对航空铝合金薄壁件侧壁高速铣削加工变形进行了有限元分析,进而提出了通过优化铣削工艺参数改善航空铝合金薄壁件高速铣削加工变形的工艺途径.

航空铝合金薄壁零件高速加工铣削力

探讨铣削力三维有限元计算方法,研究航空薄壁零件高速加工切削力变化规律。基于Advant Edge 3D铣削模块,实现对AL7075航空铝合金材料的铣削过程仿真加工并研究铣削力规律。预测不同切削时间下工件及刀具上的温度分布,建立高速铣削参数对铝合金7075铣削力和铣削温度的影响曲线。通过实际铣削试验验证仿真结果的可靠性。研究结果表明:在铣削速度v为250~1 500 m/min,切削速度大于250 m/min时,切削力随切削速度增加而快速下降;当切削速度大于500 m/min时,切削力变化不大,呈微量上升趋势;轴向力FZ在整个速度范围内变化不大;高速铣削参数对铝合金7075铣削力和铣削温度的影响曲线可辅助优化切削加工参数,有助于减小切削过程中刀具的磨损,改善刀具切削状态,提高刀具使用寿命,为预测其他材料的铣削力提供了新的有限元建模方法。

高速铣削淬硬模具钢的工艺性与经济性研究

高速加工机床及其刀具技术的最新发展使得在模具和零件制造领域实现“以切代磨”成为可能 ,用超硬刀具高速切削淬硬模具钢等难加工材料已得到越来越广泛的应用。由于模具或零件的高速切削加工可免除磨削或抛光等后续工序 ,因此精加工时如何保证工件最终表面质量同时将加工成本控制在可接受范围之内是研究人员关注的重要问题。本文在调查的基础上分析了用于高速铣削淬硬模具钢的整体硬质合金涂层立铣刀的切削性能和经济性 。