数控渐进成型技术在圆孔翻边中的应用

将数控渐进成型技术应用在圆孔翻边中,研究了翻边过程中成型力与零件壁厚的变化,分析了成型工艺参数(成型工具头直径、每层进给量和零件的最终孔径)对板料翻边成型过程的影响规律.结果表明:传统翻边工艺中用来衡量板料最大翻边变形程度的极限翻边系数不能应用在渐进成型翻边中;翻边过程中成型力在成型的最后阶段明显减小;翻边成功与破裂的零件相比较壁厚均匀;成型工具头与每层进给量越大可以成功翻边的板料预制孔越小;当零件最终孔径与成型工具头直径之比≤2.5时零件破裂形式为孔口边缘伸长率达到极限值而破裂;其他加工参数一定时,随着成型零件最终孔径的增加,板料初始有效变形长度在达到一定值后不再增加.     

翻边模的类型及其设计

用普通模具在板料上进行内孔翻边或在外缘上搬边，由于受多种因素的限制，增加翻边高度较困脉。为了获得较高的凸缘，本文介绍翻边拉伸复合冲压工艺和工艺参数的计算；以及多工位连续式翻边复合模的典型结构。一、工艺计算1．翻边系数圆孔翻过的变形特点是还料受切向与径向拉伸     

后轮罩封板翻边工艺优化研究

以汽车后轮罩封板为研究对象,对其翻边成形工艺进行分析,指出翻边缺陷产生的实质是翻边边缘切向应变的绝对值超过成形极限;以减小翻边边缘处切向应变绝对值为优化指标,对影响翻边成形性能的三个工艺参数:压边力、摩擦润滑条件、模具间隙进行正交设计,运用有限元模拟软件Dynaform进行模拟试验得到优化工艺方案;最后对优化方案进行实验验证,结果表明,数值模拟试验是可靠的,得到的优化方案可以避免翻边成形中的缺陷。     

板料柔性拉边成形与压边成形方式的比较

柔性拉边成形是在已有冲压成形工艺的基础上结合柔性拉形原理诞生的一种新型板料柔性成形方法。用柔性拉边技术代替传统压边技术,可实现球形件、鞍形件、盒形件、非规则曲面件及带凸台曲面件等三维曲面件的柔性成形。探讨柔性拉边成形原理及工艺,建立柔性拉边成形过程的有限元模型;为验证柔性拉边成形工艺的可行性和通用性,建立鞍形件多点模具成形及带凸台曲面件整体模具成形过程的有限元模型,通过对比分析拉边成形和压边成形方式,研究不同成形方式对板料起皱拉裂缺陷、应力应变分布、流动及回弹情况的影响。结果表明:压边成形时,板料容易产生起皱、拉裂等缺陷,较难得到高质量的成形件;而在相同条件下,采用拉边成形方式所得成形件应力应变分布均匀、回弹小,拉边力抑制起皱、拉裂等缺陷的产生,同时板料流动更均匀。     

基于Dynaform的汽车电动机外壳多工位成形模拟及模具设计

针对传统的板料多次拉深工艺的多样性和复杂性,模具结构复杂,周期长以及成本高等特点,提出了基于CAE分析的拉深工序设计方法。以汽车电动机外壳为例,分析了带凸缘筒形件拉深工艺特点,通过理论公式计算出拉深成形所需的各种数据,基于Dynaform成形仿真检验各次拉深方案的可行性,分析电动机外壳在冲压拉深成形过程中的成形极限,预测成形缺陷,找出缺陷产生的原因,进而调整拉深成形工艺参数,最终设计出合理的级进模具结构。     

C形管筒折弯成形预测模型研究

将人工神经网络理论应用于板料折弯成形工艺的研究，采用正交试验原理进行样本数据设计，在试验和有限元分析基础上获取样本试验数据，建立板料折弯成形中上下模半径、下模开口、板料厚度、折弯力工艺参数与折弯角之间的人工神经网络数学模型。该模型的建立为板料折弯成形这种多变量、非线性系统问题的解决提供了一个有效的工具。     

基于非线性有限元的钣金件成形极限研究

用非线性有限元软件包 SHEET- FORMING研究橡皮成形工艺的模具圆角半径和板料厚度对钣金件凹凸翻边成形极限的影响 ,建立了用于预测橡皮成形工艺成败和分析其原因的极限翻边高度 h、模具圆角半径 r凹 / r凸 、板料厚度 t的曲面关系 ,用非线性有限元法有效地取代了坐标网应变法。文中主要论述 ,以圆框为对象 (L Y12 M)和用试验得到的成形极限曲线作判据 ,选取合适参数范围作正交设计 ,用动力显式算法对凹翻边破裂数值模拟并与生产型试验结果进行对比基本吻合。     

汽车后悬支架冲压成型数值模拟分析

以某型号汽车后悬支架零件为例,在电子万能试验机上对该支架进行拉伸试验以获取其材料力学性能参数:屈服极限、屈强比和伸长率.在对其冲压成型工艺路线进行合理规划后,对扩展的毛坯、排样布局、折弯、翻边、扩孔和压凸印等冲压过程进行详细的数值模拟分析.在冲压成型过程中普遍存在折弯回弹量过大、翻边起皱、压凸印的破裂和扩孔起皱等缺陷,优化冲压设置参数有效提高零件的变形均匀性,应变矢量值控制在(-0.256788~0.284924)范围,对实际冲压成型生产过程有一定的借鉴和指导意义。     

穿过柔性体的板料U形折弯工艺研究

折弯成形在钣金工艺中应用广泛,但穿过柔性体的金属板料因折弯时的柔性体受力变形对板料成形影响较大,给大规模生产造成困难。以某型电动汽车软包电池PACK中隔板组件为例,通过单边折弯实验研究了压料力、间隙大小对其折弯成形的影响,并提出了压料力、模具间隙的选取方法;在此基础上,选用U形折弯工艺,运用Dynaform软件仿真验证U形折弯效果,并提出了进一步减少折弯回弹量的工艺措施.     

大型复杂型面铝合金翻边件电磁成形塑性流动行为研究

大型复杂型面铝合金翻边件电磁成形是一个电磁场和结构场耦合作用下的复杂塑性成形过程。由于大型复杂型面的影响,使得铝合金翻边件在电磁成形过程中的塑性流动行为与传统带凸模翻边成形不同。基于松散耦合法建立耦合电磁场和结构场的大型复杂型面铝合金翻边件电磁成形有限元模型,研究采用1层、2层和3层平板线圈电磁翻边下的板料塑性流动行为,并采用试验研究揭示了不同压边力控制下板料法兰部分塑性流动规律。结果表明,当采用3层平板线圈时,翻边件的复杂型面部分完全贴膜,法兰部分材料进入凹模腔的部分更多,促使板料发生更多的塑性流动;不同压边力控制下,法兰部分由塑性流动产生不同的工件形式,在压边力不足时,法兰部分产生明显的起皱现象;通过合理的压边力控制,可得到贴膜性良好的大型复杂型面铝合金翻边件。     

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.