高速磨削机床研究综述

高速磨削技术相对于普通磨削具有众多优势,进而催生了高速磨削机床的需求。本文首先综述国内外高速磨削机床的研究现状,然后对高速磨削机床核心部件:床身、主轴和磨削液系统在高速磨床中需要满足的特性进行了详细的分析和阐述;最后对高速磨床高速下的动力学特性研究意义和方法进行了详细的综合和说明,为高速磨床的发展提供借鉴和指导。     

高速大扫描范围原子力显微镜系统的设计

针对目前高速扫描型原子力显微镜(AFM)主要是限于物检测且扫描速度和扫描范围均有待提高,提出了一种高速原子力显微镜结构设计方案。在压电陶瓷致动器驱动的柔性铰链结构式位移台的基础上,构建了AFM大范围扫描器,使原子力显微镜在x-y扫描方向的运动范围达到了100μm×100μm。通过傅里叶频谱分析,计算获得了AFM扫描器常用的三角波驱动信号和正弦波驱动信号的高次谐波特性及其对AFM高速扫描成像的影响程度。为了消除在扫描运动过程中的机械自激振荡,提出了将正弦波信号作为高速扫描的驱动信号,行扫速度达到50line/s。在正弦波驱动的基础上提出了一种基于位置采样的图像获取方法,有效地减小了AFM扫描器的非线性误差造成的图像畸变现象。     

工作台各速度段激光直写二元图案

为了进一步提高直角坐标激光的直写效率,提出了一种扫描工作台各速度段进行激光直写二元图案的方法。该方法用扫描工作台的位置反馈脉冲同步触发激光束曝光光刻胶,实现像素点的理想位置曝光;而且依据扫描工作台的运动特性和匀速直写时各像素点获得的曝光量情况,对处于扫描工作台加、减速度段的像素点的曝光强度进行调制,保证需要曝光的像素点对应的每一个位移分辨力距离上所获的曝光量与扫描工作台匀速运动时相同,从而保证扫描工作台速度连续变化的情况下激光直写能获得预期的曝光效果。仿真实验表明:以5mm×5mm曝光图案为例,该方法所需的直写时间是传统只在匀速段直写的77.77%;同时配备的声光调制器由16位降为12位时,扫描工作台整个加速段直写产生的曝光量相对误差由0.4%上升为10%。     

基于STC单片机的激光灯控制系统设计

舞台中的激光灯以其生动、丰富的图案、神奇的变化、内容绚丽多彩的效果等的特点吸引了人们越来越多的目光,成为舞台与城市景观中不可缺少的一道风景线。随着半导体激光技术的快速发展与单片机不断的更新,本设计将新型的合光技术与高速单片机芯片相结合设计一款新型的激光灯控制系统,使各自优势充分发挥。本设计系统主由合光系统、单片机控制系统、扫描系统三部分所组成。当中核心部分为单片机控制系统,将图形数据固化在单片机EPROM内,通过内部编写的程序函数对图案数据进行各种效果控制并且将信号传输到扫描系统中,通过改变振镜电机的旋转方向及运动速度,带动振镜上的反射镜片改变角度来实现将激光束的反射,从成达到预定的图案与效果。     

高速加工中超硬材料刀具性能及进展*

对高速加工用超硬材料金刚石刀具、聚晶立方氮化硼刀具的性能,类型和国内外制造和研究现状进行综合评述.详细阐述三种高速加工用金刚石刀具性质和应用特性,国内外制造企业现状,以及聚晶立方氮化硼刀具特性及应用.并以各向同性人工合成石墨高速加工中金刚石刀具应用、发动机缸体缸盖高速铣削PCBN刀具应用、航空用钛合金高速车削PCBN刀具应用为例说明超硬材料刀具在高速加工中的优势,为制造企业选用高速加工超硬材料刀具提供指导和支持.     

小型激光切割机驱动功放的优化设计

激光切割机应用广泛,实用性强,在不同厚度的钢板材粗加工显示了它及强的高速快捷并且保证质量。在加工不同厚度木板材与其他木材加工设备比较优势为高速、高精度的曲线加工、平面二维复杂图案加工一次成型。最亮点的是有机玻璃加工,特点是高精度高速切割平面二维复杂图案加工一次成型。     

吹气节能

本文介绍了收缩喷嘴的低速吹气与高速吹气流动图案的区别及其特点。给出了计算低速吹气的流动特性参数的计算公式。从节能出发,提出如何合理选择控制喷嘴的气动回路,如何选择配管尺寸,如何选择喷嘴的形状及吹气时间,如何进行喷嘴的使用参教的合理匹配,如何测定高速吹气喷嘴的使用参数的合理匹配,并时有关资料中的不正确数据予以指正。     

高速高精度SPM研究现状及发展趋势

如何实现高速高精度的扫描探针显微镜（SPM）扫描已经成为国际上研究的一个热点问题,扫描器动态响应性能的好坏、控制算法的优化以及电子学系统的设计等,都将影响SPM的扫描速度和精度。本文介绍了SPM在半导体工业检测和生物检测等应用中的不足,归纳了国际上对高速SPM研究的主要研究成果,分析了各个研究方法的特点和不足,对实现高速SPM扫描的主要问题进行了概括总结。     

基于双向扫描算法的小线段速度规划

为提高数控系统加工产品的速度,提出了基于双向扫描算法的小线段速度规划方法.以直线加减速为例,导出小线段加工过程中进给速度的关键约束条件,建立了小线段高速加工的衔接速度规划数学模型,提出一种以最大进给速度为目标的双向扫描算法,以获得路径段衔接点处的最优进给速度.该方法通过对加工路径的正反向扫描,得到满足小线段路径的几何特性和机床的物理限制等多种约束的衔接点进给速度可行域.仿真和加工结果表明,该方法能实现衔接点进给速度的高速衔接,大大提高了加工效率.     

高速主轴系统静止及运转状态下动力学特性对比分析

在静止和运转状态下,高速主轴系统动力学特性会有一定程度的差异,因此,用静止状态刀尖点频响函数预测主轴系统切削加工过程中的稳定性,有时会引起较大的误差。基于此,在详细介绍高速主轴系统在运转状态下有限元建模及分析方法的基础上,以某高速主轴系统为研究对象,采用有限元法对比分析了该主轴系统静止状态、低速运转状态、高速运转状态时的固有特性和刀尖点频响函数的差异。结果表明,在低速运转状态下,该主轴系统的动力学特性同静止状态下基本相同;而在高速运转条件下,其动力学特性与静止状态下差异较大。为科学地分析同类主轴系统动力学特性和切削稳定性提供参考依据。     

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.