负游隙四点接触球轴承的刚度计算

分析了负游隙四点接触球轴承分别承受纯径向和纯轴向载荷时的载荷分布,根据Hertz理论的载荷与变形关系,推导出了负游隙四点接触球轴承径向和轴向刚度的计算公式,以QJ1830轴承为例进行了分析计算,并对正、负游隙时轴承的刚度进行了对比,结果显示负游隙时轴承的径向和轴向刚度均得到提高。     

地铁车辆用QJ型四点接触球轴承轴向游隙测量方法

对标准规定的QJ型四点接触球轴承轴向游隙测量方法的优缺点进行了分析,根据实际生产过程介绍了3种不同的游隙测量方法：分体测量方法适用于大型四点接触球轴承的测量;位置极限法通过对轴承两侧装配高度极限值进行测量后计算出游隙,误差小但测量计算过程相对繁琐;同向端面高度差法可用凸出量、凹进量仪器快速测量游隙,适用于中小型四点接触球轴承。     

异型双半内圈四点接触球轴承轴向游隙的测量

针对异型双半内圈四点接触球轴承的结构特点,对深沟球轴承的通用轴向游隙检测仪进行改进,制作了专用附件,实现了该轴承轴向游隙的精确快速测量。     

异型三点接触球轴承轴向游隙的测量方法

针对某异型三点接触球轴承需要在一定载荷下加载测量轴向游隙的要求,提出了一种使用T693S凸出量仪加载测量异型三点接触球轴承内、外圈之间的凸出量,并通过凸出量与内、外圈高度之间的关系计算轴向游隙的方法.试验表明,该方法的检测数值偏离度小于10.3％.     

2000铝箔轧机工作辊推力轴承的失效分析

铝箔轧机工作辊轴承过早失效的问题已成为铝加工行业的普遍问题。对国内某2000铝箔轧机工作辊上的四点接触球轴承的失效形式进行了分析,认为其失效的主要原因是轧机的轴向力超过了该轴承的轴向承载能力,并由四点接触球轴承轴向承载能力的计算得到了验证。因此,轧机主机设计单位在该类轴承的选型时,不仅要考虑轴承的转速、寿命,而且还要考虑轴承的轴向承载能力。     

大中型四点接触球轴承沟道中心径测量装置的改进

对四点接触球轴承沟道中心径测量装置的活动测头进行了改进,使测量装置的通用性更强,测值读数更准确,有效指导了生产中四点接触球轴承的配套,满足了成品轴承的游隙要求。     

螺杆钻具用新型推力球轴承的设计及力学分析

推力轴承组是螺杆钻具传动轴总成中的薄弱环节之一,它直接影响着螺杆钻具的使用寿命。在传统四点接触球轴承的基础上设计了一种新型推力球轴承。并利用有限元软件对设计的推力球轴承进行了力学分析,研究了轴向载荷、滚珠直径和滚道曲率半径对其力学性能的影响。结果发现,与常规的四点接触球轴承相比,改进后的推力球轴承较的应力更小。其中,滚珠的等效应力和接触应力随轴向载荷和滚道曲率半径的增大而增大,随着滚珠直径的增大而减小,且均成非线性规律变化。     

面向典型工况的四点接触球轴承接触状态分析

四点接触球轴承在实际服役环境下易出现三点、四点接触现象，复杂时变的接触特征导致其建模分析及试验研究的难度较大。首先，建立四点接触球轴承力学模型，对其接触受力及运动状态进行分析；然后，利用刚体动力学分析轴承各零件之间的瞬态几何关系；最后，利用赫兹接触和润滑理论建立力学模型，通过GSTIFF I3求解器获取轴承组件在各个时刻相互之间作用所产生的状态信息，从而得到四点接触球轴承的多点接触特征。基于上述模型开展了转速、径向载荷等工况参数对四点接触球轴承动态接触的影响分析，结果表明：当转速较高时，轴承在离心力的作用下容易出现三点接触现象，副接触对的接触力随着转速的提高而逐渐增加；当径向载荷与轴向载荷比值增加到一定程度时，轴承易出现四点接触现象。     

风机轴承“瘦身”

带定位轴承是由一个单列圆锥滚子轴承(TRB,这个单列圆锥滚子轴承在正常的正转距工况下承受主要的径向和轴向载荷)和一个经过仔细设计辅助挡环组成,这个辅助挡环的作用是在风机刹车或启动时有反转力距的情况下承受轴向力的。该轴承可以作为四点接触球轴承(FPCBB)与单列圆柱滚子轴承(CRB)组合方案、或者四点接触球轴承(FPCBB)与双列TRB组合方案的替代方案。     

角接触球轴承静态刚度试验

角接触球轴承在径向、轴向以及力矩方向联合载荷作用下,内外圈将产生径向、轴向相对位移及相对倾角。这种弹性相对位移量的大小关系到轴承的使用性能。为了得到角接触球轴承静刚度,提出了角接触球轴承静刚度的测试方法。设计了测量装置,获取施加不同载荷作用下角接触球轴承的静刚度。分析结果表明:随着轴向载荷或径向载荷的增大,轴向变形或径向变形基本上呈现线性增长,轴向刚度和径向刚度呈现非线性增长;随着轴承尺寸的增大,轴承的静态刚度也增大。     

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。     

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.     

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....     

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.