Experimental analyses to investigate the feasibility and effectiveness in using heat-pipe embedded end-mills

This study experimentally verifies the feasibility and effectiveness of heat-pipe cooling in end-milling operations. The basic idea is to embed a heat-pipe at the center of an end-mill with the evaporator close to the tool tip, and the condenser at the tool end. Thus, most of heat generated on the end-mill tip can be quickly removed dependent on convection heat transfer by means of heat-pipe. The end-milling experiments were carried out on a CNC vertical machining center under three different cooling conditions, including dry milling, fluid cooling, and heat-pipe cooling. The work material was AISI 1040 steel, and hard alloy was chosen for the cutting tool material. Flank wear is considered as the criterion for tool failure and the wear was measured using a Hisomet II Toolmaker's microscope. The tests were conducted until the end-mill was rejected when maximum flank wear equal to 0.30?mm was recorded. The results validate that heat-pipe-assisted cooling in end-milling processes can effectively perform thermal management comparable to the fluid cooling used pervasively in the manufacturing industry, increasing the service life of the end-mill.     

自由曲面5轴数控加工刀位轨迹的生成算法

应用计算几何技术来决定优化的刀具定位和刀具姿态以实现环形刀的5轴自由曲面数控加工。环形刀起切削作用的环形部分曲率半径的变化范围更大,而且刀具姿态随曲率而变化。这些特性使得该方法比平底刀且固定刀具姿态的加工方法更优越。分三部分来实现：①优化刀具定位和刀具姿态。②刀具轨迹规划。③干涉检测。     

Extraction of flank wear growth models that correlates cutting edge integrity of ball nose end mills while machining titanium

The application of titanium alloys are increasingly seen at aerospace, marine, bio-medical and precision engineering due to its high strength to weight ratio and high temperature properties. However, while machining the titanium alloys using solid carbide tools, even with jet infusion of coolant lower tool life was vividly seen. The high temperatures generated at the tool?Cwork interface causes adhesion of work-material on the cutting edges; hence, shorter tool life was reported. To reduce the high tool?Cwork interface temperature positive rake angle, higher primary relief and higher secondary relief were configured on the ball nose end-mill cutting edges. However, after an initial working period, the growth of flank wear facilitates higher cutting forces followed by work-material adhesion on the cutting edges. Therefore, it is important to blend the strength, sharpness and surface integrity on the cutting edges so that the ball nose end mill would demonstrate an extended tool-life. Presently, validation of tool geometry is very tedious as it requires extensive machining experiments. This paper illustrates a new feature-based ball-nose-end-mill?Cwork interface model with correlations to the material removal mechanisms by which the tool geometry optimization becomes easier. The data are further deployed to develop a multi-sensory feature extraction/correlation model to predict the performance using wavelet analysis and Wagner Ville distribution. Conclusively, this method enables to evaluate the different ball nose end mill geometry and reduces the product development cycle time.     

基于表面二维PCA重构图像的刀具磨损分形特征研究

根据加工表面纹理图像与刀具几何形状之间的内在联系,提出利用计算机视觉技术进行刀具磨损状态监测,设计了基于表面微观纹理图像的刀具磨损状态监测实验系统。提出从二维PCA重构图像中提取分形特征值来判断刀具的磨损状态,给出了二维PCA图像重构算法。理论分析和实验证明:PCA重构图像消除了原始图像信息中的冗余和噪声,从重构图像中提取出来的分形布朗运动维数与刀具磨损有着很强的相关性,可以间接判断刀具磨损情况,从而达到对刀具状态进行监测的目的。     

五轴加工中基于局部几何条件的刀具势态优化

文中给出了五轴加工中环形刀具势态优化的两个条件，并根据牡潘标线的几何意义，分析了加工曲面和刀具曲面的局部几何特性。在此基础上提出了一个刀具势态优化的新方法，从而使五轴加工的效率得到进一步提高。     

数控铣削参数的回归分析及优化处理

结合数控加工时的具体工况,利用实验数据建立参数的回归方程,用一元线性回归和正交多项式分析各参数之间的联系,并且推出了经验公式;利用回归方程数据库建立目标数学模型,对铣削过程中进行预测控制和优化处理;在受所选机床的主轴转速、进给量、进给力、切削扭矩、机床功率、工件质量等限制的基础上确立了机床约束条件,为生产现场提供参考数据。     

浅谈顺铣与逆铣在铣削加工中的应用

在铣削加工中,采用顺铣还是逆铣方式是影响加工表面粗糙度及刀具切削寿命的重要因素之一.铣削方式的选择应视零件图样的加工要求,工件材料的性质、零件在加工中装夹的受力特点以及机床、刀具等条件综合考虑顺铣与逆铣在铣削加工中的应用.在现代加工技术中,各单位对于顺铣与逆铣的应用情况也不尽相同.因此需要掌握顺铣与逆铣的知识和在加工中的应用及切削力的分析.     

基于轴向位置的振动钻削切削力计算

轴向振动钻削提高了难加工材料的加工性能,但是至今还没有一套成熟的理论体系,能系统说明振动过程机理,对切削力的公式也没有形成一致的观点和方法。本文通过对轴向振动钻削工艺参数分析的基础上,对实际钻削加工区段分两部分进行计算,并利用轴向位置方法,建立了一套可以针对不同材料加工要求的瞬时切削力与各参数的关系模型。     

An experimental investigation of dry cutting performance for machining gray cast iron with carbide coating tool

The orthogonal experiment was made for the dry cutting of gray cast iron by coated cemented carbide cutting tool. The regression analysis was made for the experimental data by the least square method. The empirical equation of the cutting force was obtained under the dry cutting condition. The influence rule of the cutting parameters on cutting force was analyzed, and the abrasion modality and mechanism of the tool were studied. The reasonable cutting parameters of the processing of gray cast iron by coated cemented carbide cutting tool under the dry cutting condition were obtained by the analyses of the cutting efficiency versus cutting force of the tools. This study provided a fundamental basis for the optimization of the cutting technological parameters for gray cast iron.     

空调设备故障诊断专家系统的设计

本文简述了用Ｐｒｏｌｏｇ语言设计的空调设备故障专家系统，该专家系统的主体由预测模块和推理模块组成，其预测模块可作为这类专家系统的模糊统计决策的外壳，推理模块可作为调用具体型号空调设备故障诊断知识库的工具。     

FMS刀具切削状态实时在线监测智能系统

论述了一个刀具切削状态实时在线监测智能识别系统的组成原理和构造,提出了一种新型流体声发射和电动机电流的综合传感新方案,建立了机床控制系统与智能监测系统的并行通信和发具切削状态识别的专家决策系统,根据不同的工况条件自动选择传感方式、监测模式和识别方法,形成了一套完整的在线监测智能识别系统。     

Tool wear monitoring by machine learning techniques and singular spectrum analysis

This paper explores the use of data mining techniques for tool condition monitoring in metal cutting. Pseudo-local singular spectrum analysis (SSA) is performed on vibration signals measured on the toolholder. This is coupled to a band-pass filter to allow definition and extraction of features which are sensitive to tool wear. These features are defined, in some frequency bands, from sums of Fourier coefficients of reconstructed and residual signals obtained by SSA. This study highlights two important aspects: strong relevance of information in high frequency vibration components and benefits of the combination of SSA and band-pass filtering to get rid of useless components (noise).     

Improved dynamic cutting force model in peripheral milling. Part II: experimental verification and prediction

Cutting trials reveal that a measure of cutter run-out is always unavoidable in peripheral milling. This paper improves and extends the dynamic cutting force model of peripheral milling based on the theoretical analytical model presented in Part I [1], by taking into account the influence of the cutter run-out on the undeformed chip thickness. A set of slot milling tests with a single-fluted helical end-mill was carried out at different feed rates, while the 3D cutting force coefficients were calibrated using the averaged cutting forces. The measured and predicted cutting forces were compared using the experimentally identified force coefficients. The results indicate that the model provides a good prediction when the feed rate is limited to a specified interval, and the recorded cutting force curves give a different trend compared to other published results [8]. Subsequently, a series of peripheral milling tests with different helical end-mill were performed at different cutting parameters to validate the proposed dynamic cutting force model, and the cutting conditions were simulated and compared with the experimental results. The result demonstrates that only when the vibration between the cutter and workpiece is faint, the predicted and measured cutting forces are in good agreement.     

基于数控纵切自动车床上镍基高温合金的加工

随着航空航天工业的发展,对于高温合金工件的需求日益增长。针对镍基高温合金现场加工难、切削性能差和刀具磨损快等问题,本文在数控纵切自动车床上采用切削试验的方法,对镍基高温合金GH2132在不同切削工况下的刀具磨损以及零件表面质量进行了对比分析,明确了适用的刀具和合理的切削用量及切削速度。分析认为,性能优异的涂层刀具在选择了合适的进给量之后,完全能够满足镍基高温合金的切削加工,相对于其他硬质合金刀具,无论在生产效率还是产品质量方面,都有了很大的提升,并且节约了生产成本。     

用解析法计算高速切削单涂层刀具瞬态温度分布

为研究涂层在切削中对刀具温度的影响,为设计刀具涂层提供理论依据,分析高速切削过程中切削热的产生和刀具边界情况,建立单涂层刀具热传导物理模型和数学模型,用数学解析的方法推导出正交高速干切削过程中单涂层刀具体内部的温度分布公式。利用推导出的温度公式对TiN、TiC、Al2O3涂层刀具的切削温度分布进行解析计算,并将解析计算结果与数值分析结果进行比较。结果表明,解析计算结果与数值计算结果吻合很好;涂层材料与基体材料的热物理性能以及涂层的厚度对刀具的温升有重要影响;随着热流密度的增加,涂层厚度对刀具内部的温度影响增大。     

FPGA-based reconfigurable system for tool condition monitoring in high-speed machining process

We present a reconfigurable system to detect and indicate online and in real time, the cutting tool conditions in high-speed face milling. It consists of a data acquisition system (DAS) and a hardware signal processing (HSP) unit. The DAS acquires and digitalizes the cutting vibration signals generated from machining tests performed under different tool conditions and cutting parameters. The HSP unit processes the digitalized vibration signals using reconfigurable IIR band-pass digital filter and statistical techniques, designed and implemented into a single field-programmable gate array (FPGA) and coefficients read-only memories. The system operation is divided into learning and monitoring modes. The tool condition is indicated by an alarm signal, one LED indicator, and a message shown on four-digit seven-segment displays. In all experiments, the system correctly detected the tool condition. The proposed system is fast, compact, reliable, and economical, and no modification of the machine-tool structure is required.     

高铬铸铁的切削用量优化计算

在考虑刀具动态强度的条件下，利用有限元法对用复合陶瓷刀具加工高铬铸铁的切削用量进行了计算，为经济有效地加工高铬铸铁提供了理论依据。     

Cutting performance of nano-crystalline diamond (NCD) coating in micro-milling of Ti6Al4V alloy

Hard coatings are an important factor affecting the cutting performance of tools. In particular, they directly affect tool life, cutting forces, surface quality and burr formation in the micro-milling process. In this study, the performance of nano-crystalline diamond (NCD) coated tools was evaluated by comparing it with TiN-coated, AlCrN-coated and uncoated carbide tools in micro-milling of Ti₆Al₄V alloy. A series of micro-milling tests was carried out to determine the effects of coating type and machining conditions on tool wear, cutting force, surface roughness and burr size. Flat end-mill tools with two flutes and a diameter of 0.5 mm were used in the micro-milling process. The minimum chip thickness depending on both the cutting force and the surface roughness were determined. The results showed that the minimum chip thickness is about 0.3 times that of the cutter corner radius for Ti₆Al₄V alloy and changes very little with coating type. It was observed from wear tests that the dominant wear mechanism was abrasion. Maximum wear occurred on NCD-coated and uncoated tools. In addition, maximum burr size was obtained in the cutting process with the uncoated tool.     

用切削速度模型求解剪切角的新方法

通过对切削区速度场的分析，建立了切削过程的速度模型。根据此模型，导出了二元切削时求解剪切角φ的简化公式。此公式的计算结果比现有的其他公式更接近实际情况。由此得出结论：在切削过程中，剪切角φ的大小不仅取决于刀具前角γｏ，而且和被切材料在剪切前后的速度之比｜ｖ｜／｜ｖｃ｜有较大关系。     

现代刀具材料系列讲座（三）：涂层高速钢刀具

介绍了涂层高速钢刀具的切削性能,并列出了涂层与未涂层高速钢刀具的对比切削数据。