基于田口法和响应面法的数控铣削工艺参数能效优化方法

为研究机床能量效率与工艺参数耦合的复杂机理,提出一种基于田口法和响应面法的数控铣削工艺参数能效优化方法。分析加工过程中的能耗特性,建立了数控铣削加工能量效率函数。基于田口法规划优化实验,并基于响应面法建立工艺参数与比能和加工时间的回归方程,构建了以铣削加工工艺参数为变量、以高能效和高效率为优化目标的多目标优化模型。使用多目标粒子群优化算法对该模型进行求解,并通过实验数据和算法优化结果分析了加工过程中工艺参数与比能及加工时间的关联关系。     

面向能量效率的数控铣削加工参数多目标优化模型

切削参数是数控加工工艺中的重要组成,切削参数的合理选择能够显著影响到机床能量效率。为提高机床能量效率,分析数控铣削加工的能耗构成特性和加工时段能耗特性,建立数控铣削加工能耗模型,并通过非线性回归拟合获取能耗模型的相关系数,建立了以最高能量效率和最小加工时间为目标的多目标优化模型,采用连续禁忌算法对模型进行优化求解。通过算法优化结果与试验结果进行对比分析,验证了能效模型的有效性。     

基于过程集成优化的复杂曲面数控铣削性能分析

针对复杂自由曲面变曲率、大扭曲的特征及其铣削性能难预测的问题,提出加工过程的集成优化的切削性能分析方法,在曲面多轴铣削工作流程中综合评价和提高切削加工效率和质量。建立了自由曲面体零件多轴加工集成优化铣削模型,集成切削加工刀位轨迹计算、切削仿真与机床运动仿真、切削力预测、工艺参数优化工作流程及其输入输出文件,实时从输出文件中解析提取计算结果参数,有效分析预测切削参数与切削力对加工效率和质量的影响,实现复杂自由曲面铣削过程的集成与全局优化。将该方法应用于大型混流式水轮机叶片的数控铣削性能分析,并与生产数据进行对比,进一步验证了所提加工过程集成优化方法可有效分析和预测大型自由曲面的数控铣削性能。     

数控铣削加工工艺参数优化方法综述

介绍了铣削力、铣削用量等数控铣削加工工艺参数,分析了材料去除率、表面粗糙度、能耗、铣刀颤振等工艺指标,并给出了数控铣削加工工艺参数的优化目标、优化方法、现有试验研究,以及近似模型。所做研究可以为数控铣削加工工艺参数的选择和优化提供理论参考。     

面向能耗的2.5D型腔数控铣削加工刀具组合优化选择

为降低数控机床的能量消耗,深入研究了2.5D型腔数控铣削加工过程中的刀具组合优选问题。系统地分析了刀具组合与2.5D型腔数控铣削加工过程能耗的映射关系,揭示了刀具直径和刀具可行域对加工能耗的影响,并构建了多刀具数控铣削加工能耗函数。建立了以可行刀具为优化变量、以能耗和成本为优化目标的数控铣削加工刀具组合多目标优化模型,提出一种基于有向图和Dijkstra算法的刀具组合优化求解方法。以某2.5D型腔数控铣削加工刀具组合优选为例开展实验,验证了所提模型与方法的有效性和实用性。     

基于GA-BP与NSGA-Ⅱ的数控铣削参数优化研究

高效低碳制造是可持续发展的关键,而数控铣削作为常用的金属表面加工方法存在刀具寿命短、碳排放量高的问题。提出基于NSGA-Ⅱ的GA-BP多目标优化方法,通过分析不同加工参数条件下的数控铣削刀具寿命及碳排放数据集,建立GA-BP神经网络刀具寿命及碳排放预测模型。基于NSGA-Ⅱ算法建立以刀具寿命、碳排放量为目标的主体优化模型,调用构建的GA-BP神经网络模型作为目标函数进行优化求解,得到Pareto最优解集。对Pareto最优解集进行TOPSIS最优解决策,得到综合优化刀具寿命与碳排放量的加工参数组合。优化结果表明：该方法既可以对数控铣削刀具寿命及碳排放量进行准确预测,还可以对两者进行有效优化,对数控铣削参数优化具有一定的理论指导意义。     

基于遗传算法的铣削用量优化

基于数控铣削加工的特点,建立了以最大生产率、最低生产成本为目标函数,以机床、刀具、工艺等限制因素为约束条件的铣削用量优化数学模型,并运用遗传算法,结合铣削实例,对铣削用量进行了优化。     

基于数值模型的数控加工中切削力与稳定域仿真

针对数控铣削加工工艺参数选择存在的问题,以球头铣刀高速铣削过程为研究对象,建立了考虑机床-刀具-工件系统振动的非线性动力学模型,分析了铣削力中的动态分量对切削颤振的影响,在考虑再生颤振的基础上建立非线性动力学模型.基于动态铣削力建模和颤振稳定域分析计算,提出了机床切削系统稳定性极限预测方法,并对其进行仿真分析,为铣削加...     

数控铣削加工中过欠切成因及对策

简要阐述了数控铣削加工过程中所出现的过欠切现象,并从系统刚性、刀具、铣削方式方法、进给速度、程序指令、工艺安排等六个方面进行成因分析,同时也提出了解决对策,为数控铣削加工时进行正确的工艺分析、合理的编制加工程序提供了可靠的依据,从而提高数控铣削加工精度以及生产效率。     

数控铣削加工工艺参数优化方法分析

介绍数控铣削加工工艺和数控铣削加工工艺参数优化方法,通过切削深度及其参数优化、高速铣削加工及其切削参数的确定、五轴铣削加工工艺优化,有效保证数控铣削加工的可靠性与合理性。因此,分析加工工艺参数优化方法对数控铣削具有重要意义。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.