蒙皮柔性夹持数控切边的有限元分析方法及系统开发

基于可重构柔性工装的蒙皮数控切边技术属于新一代蒙皮数字化制造工艺,保证工艺系统刚度是该技术实际应用的难点之一。为了校验切边过程的稳定性,利用单元生死技术实现了蒙皮切边过程的有限元仿真,并基于ABAQUS平台开发了切边数值模拟分析系统,预测切边轨迹的振动情况。为了给仿真分析提供精确的铣削力,结合铣削力理论模型和铣削力试验,建立了航空铝合金蒙皮材料2024-T3的铣削力预测模型。最后给出了仿真分析实例,结果表明,该系统可以预测柔性夹持下的蒙皮切边过程的应力、振动,能为蒙皮数控切边技术的生产实际应用提供技术保障。     

飞机蒙皮吸盘式柔性工装系统研究

针对我国飞机生产制造业传统模式中一种零件一套专用工装的问题,采用数字化柔性工装技术的方法,研制了一套柔性工装系统,替代了多个固定工装。对应用于飞机蒙皮等零件的柔性工装系统进行研究,该系统通过电机带动立柱阵列进行三维运动控制,利用可调立柱阵列对蒙皮进行定位,采用真空吸盘对蒙皮进行吸附夹紧,最终实现了飞机蒙皮零件的重建、定位和吸附夹紧。最后用激光跟踪仪对柔性工装系统的运行精度进行检测,结果表明X、Y、Z三个方向的定位精度均在±0.1mm以内、重复定位精度均在±0.05mm以内。     

钣金零件用真空夹持工装研制

简要介绍了真空夹持工装的工作原理,并以卡板支撑式真空夹持工装为重点说明了该类工装的结构设计,对同类工装夹具的设计有很大的借鉴作用。真空夹持工装利用真空吸附原理,采用真空吸盘将钣金零件吸附固定在定位装置上,解决了钣金零件刚度差,不易固定夹紧的问题。钣金零件在该工装上定位夹紧后,可以在数控机床上进行钻孔、切边和划线等操作。该真空夹持工装尤其适用于大型钣金零件,不但提高了加工效率和精度,而且大大降低了工人的劳动强度。     

高压油泵单元壳体随行夹具开发

通过对高压油泵单元壳体零件的工艺分析,研究自动化生产线的需求,将车床加工工装、加工中心加工工装、机器人夹持等结合起来,设计带有车床夹具、加工中心夹具、机器人夹持等标准接口的随行夹具,实现了复杂异型零件的多工序自动化加工,通过改进随行夹具对相似零件的定位装夹,使柔性混线生产成为可能。     

飞机长桁切边柔性夹具的机械设计及仿真

针对国内航空制造业在长桁工件切边中使用的装夹夹具专业性强、定位精度低、经济性不高、不适用现代化航空制造的需求,设计了一种飞机长桁零件切边的柔性夹具。运用CATIA V5R20对柔性夹具进行建模、装配,并应用DELMIA的PDM模块对夹具夹持工件的运动过程进行模拟仿真,检查干涉并优化结构。最终设计出满足要求的柔性夹具。     

一种加工悬空零件的积木式柔性工装研究

通过对悬空零件加工中弹刀现象的分析,探索悬空零件加工的新方法,提出利用积木式柔性工装来消除悬空零件加工中的弹刀现象,解决定制专用工装加工悬空零件时生产周期长且制造成本高的问题,从而提高零件加工表面质量,缩短零件生产周期,降低制造成本。     

蒙皮镜像铣切系统及先进制造工艺的应用

针对飞机蒙皮零件传统工艺方法无法满足精确制造和绿色制造的需求,对数铣替代化铣的飞机蒙皮厚度精确加工技术进行研究,采用集蒙皮切边、开口、制孔和厚度精确加工于一体的蒙皮镜像铣切系统,实现了飞机蒙皮的精确制造.介绍了国内首台蒙皮镜像铣切设备的系统工作原理及应用状况,对比分析了传统工艺方法与蒙皮镜像铣切系统先进制造工艺及数字化柔性工装技术的优势.通过实际应用验证:蒙皮一体化加工技术的应用使我国航空制造技术迈入了飞机蒙皮精确一体化制造领域,推动了我国航空制造技术的发展.     

落料,拉深,切边复合模

我厂加工的一种零件如图1所示,原来的加工工艺是采用在生产工序中预先留有一定的切边余量,以消除拉深过程中产生的荷叶边。消除方法是在车床上使用专用工装单个车削完成,或者是成批在平面磨床     

飞机框组件工装的模块化设计研究

以工装通用性设计为研究重点,以期节约工厂的装配生产用地,缩短飞机生产制造周期.主要采用模块化设计思想,综合分析框类零件的结构形式和连接特点,结合柔性工装装配技术,设计一套某机型后机身三个框的通用工装,进行三维实体建模,实现工装的快速定位和拆装,减少夹具和定位器的数量,验证工装模块化设计方案.     

多点定位式柔性夹持工装设计与研究

为了解决飞机、汽车等行业的薄壁零件在常规方法定位加工中劳动强度大、自动化程度低、生产效率低、成本高、质量不稳定,且因形状复杂、刚度低不易定位夹持等问题,提出了基于多点真空吸附式柔性夹持工装方法。设计了一套X-Z两坐标的点阵式机械结构和采用真空泵系统的真空回路,并运用CATIA有限元分析模块对工装横梁的强度和刚度进行了校核,完成了一套用于薄壁零件的柔性工装系统。结果表明该设计满足要求,系统能有效提高制造柔性,为解决传统定位方法的缺陷提供了一种思路。     

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.     

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....     

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.     

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.