An experimental study of tool wear and cutting force variation in the end milling of Inconel 718 with coated carbide inserts

Inconel 718 is a difficult-to-cut nickel-based superalloy commonly used in aerospace industry. This paper presents an experimental study of the tool wear propagation and cutting force variations in the end milling of Inconel 718 with coated carbide inserts. The experimental results showed that significant flank wear was the predominant failure mode affecting the tool life. The tool flank wear propagation in the up milling operations was more rapid than that in the down milling operations. The cutting force variation along with the tool wear propagation was also analysed. While the thermal effects could be a significant cause for the peak force variation within a single cutting pass, the tool wear propagation was believed to be responsible for the gradual increase of the mean peak force in successive cutting passes.     

Al2O3/Cu复合材料的内氧化制备及性能研究

采用高能球磨制备出亚稳态的Cu-1%Al（质量分数）合金粉,再将Cu2O粉与其一起进行高能球磨,然后将复合粉末压坯在N2保护炉中同时进行氧化和烧结,制备出Al2O3/Cu复合材料。分析了分别采用湿法球磨和干法球磨时的合金化效果,讨论了模压压力对材料性能的影响。结果表明,对于Cu-Al混合粉来说,采用湿法球磨容易产生分层,采用干法球磨具有良好的合金化效果;在本试验条件下,750MPa为最佳的模压压力,但烧结后材料的电导率还是偏低,因此有必要进行后续的处理来进一步提高材料的性能。     

电火花铣削中电极损耗及补偿的几何描述方法

提出了电火花铣削加工的基于数学模型的电极分解加工补偿法，即通过将电火花铣削加工过程划分为两个阶段——型腔侧面轮廓加工和底面的加工，这样就简化了放电状态的检测和电极补偿运动。在分别对侧面和底面加工过程分析的基础上，建立了侧面轮廓和底面加工的电极损耗和补偿的数学模型，为电极自动在线补偿提供了理论基础。     

制粉工艺对贮氢合金电化学性能的影响研究

研究了干法、湿法和湿法加添加剂三种制粉工艺对贮氢合金电化学性能的影响 ,结果表明 :制粉工艺对合金粉末的表面形貌、粒度分布、氧含量均存在很大的影响 ,并影响到其电化学性能。当采用湿法制粉工艺时 ,贮氢合金电极的活化性能较干法制粉明显改善 ,若加入一定量的添加剂 ,活化性能进一步提高 ,第一次放电容量即达到2 78mAh·g-1,第二次放电容量达到合金电极的稳定容量 32 2mAh·g-1。湿法制粉对贮氢合金电极的循环稳定性能有一定的负面影响 ,这可能与贮氢合金粉末表面的氧化和细粉相对含量较多有关 ,然而 ,当加入一定量的添加剂以后 ,贮氢合金电极的氧含量得到有效的控制 ,3C充放循环稳定寿命达到 5 0 0次 ,与干法制粉工艺接近。     

Flute breakage detection during end milling using Hilbert–Huang transform and smoothed nonlinear energy operator

Real time tool condition monitoring has great significance in modern manufacturing processes. In order to prevent possible damages to the workpiece or the machine tool, reliable monitoring techniques are required to provide fast response to the unexpected tool failure. Milling is one of the most fundamental machining operations. During the milling process, the current of feed motor is weakly related to the cutter condition, the change of power consumption is not significant to identify tool condition. Thus, current of motor-based tool condition still requires some new approaches to sort out significant pattern that could be employed to indicate tool condition. In this paper, a new approach is proposed to detect end mill flute breakage via the feed-motor current signals, which implements Hilbert–Huang transform (HHT) analysis and a smoothed nonlinear energy operator (SNEO) to extract the crucial characteristics from the measured signals to indicate tool breakage. Experiments on a CNC Vertical Machining Centre are presented to show the algorithm performance. The results show that this method is feasible and can accurately and efficiently monitor the conditions of the end mill under varying cutting conditions.     

基于VERICUT的虚拟龙门加工中心建模和仿真关键技术研究

为减少零部件试切,检验数控工艺合理性,构建了虚拟龙门加工中心。研究了龙门加工中心运动,阐述了侧面铣头运动由旋转中心和换刀点控制,提出了虚拟机床侧面铣削运动构建方法,可实现各角度侧面铣。搭建了虚拟加工环境,通过零件仿真加工,完成了零件顶面及4个侧面的铣削加工,验证了数控代码的正确性,检验了数控工艺合理性,减少了零件试切,缩短了开发周期,仿真结果表明虚拟龙门加工中心的正确性。     

基于遗传算法优化铣削用量的数控加工仿真系统的研究

遗传算法是一种模拟生物界自然选择和自然遗传机制的自适应搜索和优化方法,在搜索优化问题的全局或全局附近的最优解上具有良好的优势条件.文章建立了基于遗传算法思想的铣削用量多目标智能优化的数学模型及其数控加工动态仿真系统,运用遗传优化方法对铣削加工实例进行优化,并在数控加工动态仿真系统上验证了铣削用量多目标智能优化的数学模型的正确性和实用性.     

高能球磨制备Al3Ti/Al块体纳米晶复合材料

通过对Al Ti系和Al TiO2 系进行高能球磨和压制烧结制备了固态原位反应生成的纳米晶块体Al3Ti/Al复合材料。研究表明 :Al Ti合金系高能球磨后 ,各组元晶粒得到细化 ,并且Ti在Al中发生了强制超饱和固溶 ,烧结时原位反应形成纳米晶Al3Ti/Al复合材料 ;而Al TiO2 反应体系高能球磨仅发生组分晶粒细化 ,烧结时TiO2 部分还原并和Al原位反应生成纳米晶 (Ti2 O3 Al3Ti) /Al复合材料。     

高速铣削钛合金TC4切削力试验研究及切削参数优化

采用正交试验研究了高速铣削钛合金TC4粗加工阶段时切削参数对切削力的影响规律，并以Y向切削力最小和材料去除率最大为优化目标，利用MATLAB基于Pareto遗传算法优化高速铣削TC4的切削参数，结合Pareto最前沿给出了优化后的切削参数最优解集。     

Simplified and efficient calibration of a mechanistic cutting force model for ball-end milling

Accurate evaluation of the empirical coefficients of a mechanistic cutting force model is critical to the reliability of the predicted cutting forces. This paper presents a simplified and efficient method to determine the cutting force coefficients of a ball-end milling model. The unique feature of this new method is that only a single half-slot cut is to be performed to calibrate the empirical force coefficients that are valid over a wide range of cutting conditions. The instantaneous cutting forces are used with the established helical cutting edge profile on the ball-end mill. The half-slot calibration cut enables successive determination of the lumped discrete values of the varying cutting mechanics parameters along the cutter axis whereas the size effect parameters are determined from the known variation of undeformed chip thickness with cutter rotation. The effectiveness of the present method in determining the cutting force coefficients has been demonstrated experimentally with a series of verification test cuts.