基于影像仪的标准件批量检测技术应用研究北大核心

针对航修企业入厂检验现场仍采用游标卡尺、百分表、千分尺等传统人工抽检方式复验标准件,而使零件合格率和生产效率难以保证的现象,介绍了一种基于影像仪的标准件批量检测技术方案。在分析螺栓类标准件结构特点及测量特征量的基础上,设计了批量装夹定位夹具及检测程序,实现了螺栓类标准件主要尺寸自动化批量测量。     

基于影像仪的标准件批量检测技术应用研究

针对航修企业入厂检验现场仍采用游标卡尺、百分表、千分尺等传统人工抽检方式复验标准件,而使零件合格率和生产效率难以保证的现象,介绍了一种基于影像仪的标准件批量检测技术方案。在分析螺栓类标准件结构特点及测量特征量的基础上,设计了批量装夹定位夹具及检测程序,实现了螺栓类标准件主要尺寸自动化批量测量。     

数控车床用可调整定位支撑装置的研究

基于数控车床在批量加工中、长轴类零件时如何保证零件重复定位精度以及装夹生产效率方面是一个急需解决的技术难题。根据中、长轴类零件的特点,设计一种数控车床可调定位装置。实际应用表明,该装置可以解决加工批量中、长轴类零件时,工件定位不准、加工精度不高、生产效率低的问题。     

点定位装夹在薄板类零件批量加工中的应用

以托架盖板为研究对象,论述了该类零件加工中的装夹设计思路,探索了机加工件高平面度要求如何保证的问题。从控制装夹变形、残余应力变形的角度出发设计了点定位装夹工艺方案,并应用工程验证的方法对该工艺方案保证平面度效果进行了验证。结果表明,该点定位装夹工艺方案可极大降低产品加工中的装夹变形,能极好地保证薄板类零件高平面度要求。将点定位装夹工艺方案应用于托架盖板产品的批量加工,并通过CPK数据分析理论对生产数据进行了统计分析。结果表明,此工艺方案提升了批量加工中的产品稳定性,解决了托架盖板产品批量加工中平面度无法保证的难题,创造了巨大的经济效益。本研究为薄板类零件加工提供了非常好的工艺方案设计案例,为类似加工设计者提供了参考。     

漏斗形分布深孔系组合夹具

机械加工过程中,加工折线孔需将工件分两次装夹,如有多个不同角度方位的折线孔(通称"漏斗形分布孔系"),需多次装夹,操作繁琐,且难以保证精度。使用本组合夹具能快速、精确、批量地加工多个不同角度方位的折线孔,大大提高了生产质量和效率。     

带有双斜面压板的快速夹紧多工位专用夹具设计

带双斜面压板的多工位专用夹具,可一次装夹12个工件,且能够快速夹紧,满足了批量加工的要求,大大提高了生产效率,同时有效保证了需要正反双面加工、具有较高尺寸精度要求的工件质量。     

利用回转式夹具及工作台的铣床设计应用

本次设计的铣床夹具,利用回转式工作台的旋转机构实现对批量工件流水线加工,节省了空间和辅助设备,同时减少了工件生产时的机动工时和辅助工时。应用实践表明,该夹具方便装夹,维护方便,可以在保证加工工件的质量前提下,极大提高批量产品的铣削加工效率。     

基于片层体积无损测量装置装夹系统

研究了在基于片层体积测量的3维无损测量装置中,装夹系统总体设计、各零部件选型及设计,以及装夹系统的误差分析和补偿。根据装夹系统的功能需求,采用分层设计理念,设计能实现X、Y、Z轴方向以及6个对角线方向测量的装夹装置。同时对装夹系统进行误差分析,可知当装夹装置随着被测物体逐层浸入液体中时,由于测量液体的浮力,装夹装置中的连接杆会发生向上的回弹变形,从而影响片层液体的测量精度。通过理论推导回弹误差补偿公式,实现对被测物体的分层误差补偿。经误差实验验证,误差补偿后的片层误差均值由0.256 3 cm~3优化到0.006 3 cm~3,误差补偿效果明显。     

一种专用送料器的创新设计

以一种POM棒料零件在数控车床上实现批量加工为例,介绍数控车床在没有配置自动送料装置的前提下,利用程序实现棒料快速装夹的送料器的设计,提出了在数控机床上开发工、夹具的一些思路和方法,可以有效地减轻工人的劳动强度,提高劳动生产率。     

批量直齿小模数齿轮的一种简易测量方法

在批量加工过程中,由于齿轮检测过程复杂,检测时间长,对已加工好的齿轮无法形成快速检测,制约了产品的加工周期。针对直齿小模数齿轮的测量方式进行了步骤分析,发现最大的制约因素是量柱距测量过程不便捷。为了对批量直齿小模数齿轮形成快速、稳定的检测,并减少检测劳动强度,促进产品的快速生产,依据齿轮量柱距检测原理,设计制作和应用了便于快速检测直齿小模数齿轮的测量工具,形成了"嵌入式模块化测量"。使用改进后的测具进行齿轮检测,改变了检测方式,稳定了检测过程,从而使得检测效率得到了有效提高。     

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.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.