大型复杂环件缩比轧制成形的实验与模拟研究

研究了大型复杂环件形状因素和轧制速率对成形性能的影响规律。以缩比环件轧制实验和有限元数值模拟为基础，研究材料轴向转移模式及其变形机理，提出包含环件形状因素的成形性能评定方法。在此基础上，选用工业纯铅和LD10锻铝合金进行缩比环件轧制实验，得到了与数值模拟一致的结果，证实了所提出的包含环件形状因素的成形性能评定方法的可行性。同时发现，轧制速率影响环件轧制的成形性能，较大的轧制速率有利于环件轮廓填充。     

数控渐进成形工艺参数对表面质量的影响

应用数控渐进成形设备,针对铝合金锥形件进行了试验研究。通过改变成形中的润滑方式、工具头形状、工具头直径、进给量等工艺参数,并对成形后的试验件表面粗糙度和表面形貌进行测量和分析,研究成形参数对零件表面质量的影响。实验结果如下:球头工具头成形的零件表面质量优于圆柱形工具头,大直径的工具头成形零件的表面质量要好于小直径的工具头,层进给量越小,零件表面质量越好,固体润滑剂相比于液体润滑剂对5754铝合金成形的零件表面质量影响较小。     

航空铝合金复杂构件充液柔性成形过程及质量控制研究

针对某型号飞机铝合金复杂构件充液成形的失效形式,采用有限元数值模拟和试验的手段,研究了毛坯形状、液室压力等关键工艺参数对成形失效的影响,给出了铝合金复杂构件充液成形质量控制的措施,为此类型航空复杂构件的充液成形提供了技术指导。     

先进充液柔性成形技术及其关键参数研究

基于所提出的具有均匀压边力并轴向加压的板材充液柔性成形技术,面向板材液压柔性成形技术的普遍规律,成形出拉深比较高的铝合金筒形件以及其他复杂形状的零件如方锥盒形件、方盒形件、轴对称锥形件等,对其中的关键技术如初始液压加载状态、液压加载最优路径、破裂控制等一些关键参数进行了研究和优化;考虑板平面方向性系数的影响,利用数值模拟的手段对其成形过程进行了分析,指导实验研究,得出了有益的结论。     

控制臂模锻成形工艺优化设计

控制臂现阶段成形工艺多、生产效率低、劳动强度大,并且材料的利用率低于50%。通过对控制臂三维几何模型的建立,采用辊锻制坯工艺,结合控制臂的形状特点,合理的设计弯曲模。利用有限元数值模拟软件DEFORM-3D对模锻成形过程进行数值模拟,对终锻模进行了优化,提出了带阻力墙终锻模,通过数值模拟分析得出合格的锻件,并且材料利用率提高至70%。     

厚壁球形下壳体模锻

我厂生产的3NB80泥浆泵,其空气包系受压容器。为提高零件的机械强度,延长使用寿命,工艺由原铸钢件整体浇铸改为锻钢件上下壳体焊接。图1为空气包下壳体零件图,图2为下壳体锻件图。该零件几何形状类似厚壁封头,特点是外径尺寸大、孔深、壁厚、中间有高凸缘,形状特殊,锻造工艺性差,成形难。针对上述问题,我们进行了多次试验,最后在3吨蒸汽锤上采用模锻成形工艺,获得成功。实践证明,合理的出坯尺寸和锻模,是该零件锻造成形的关键。下壳体锻造分四火完工:一、二火:将钢锭切除烧冒口,然后锻成图3形状尺寸的坯件。边缘厚薄要均匀,否则翻边成形后的     

基于DYNAFORM的筒形件拉深成形数值模拟技术

应用数值模拟技术对金属板料成形规律进行研究越来越受到重视。对影响筒形件拉深成形的主要因素压边力、凹模圆角半径、凸模圆角半径、摩擦系数进行了分析,并研究了单元技术、求解格式、本构关系等金属板料成形模拟中的关键技术。应用DYNAFORM数值模拟软件,对筒形件的两道次拉深成形四种主要因素的工艺参数进行了模拟优化。模拟结果分析表明,各因素对金属板料拉深系数影响的主次顺序在不同拉深道次下是不相同的,不能一概而论,与实验结果基本吻合。     

雷达波导件塑性成形工艺分析及有限元数值模拟

以雷达上的波导件为研究对象,针对传统加工工艺的缺点以及工件形状特点,提出挤压成形工艺方案。利用有限元分析软件DEFORM对该工件的关键成形工序—反挤压过程进行刚塑性有限元数值模拟研究。通过数值模拟,观察到在不同压下测量时毛坯的等效应力、等效应变云图及挤压力与行程图,得到其金属流动规律,为合理设计模具和验证工艺提供依据。     

汽车桥壳胀-压成形工艺压制过程的数值模拟

根据汽车桥壳胀-压复合成形工艺压制过程的基本步骤,通过ABAQUS有限元模拟软件对汽车桥壳压制过程进行数值模拟。研究了汽车桥壳压制过程中模具运动方式以及预制坯内部压强大小对桥壳成形件质量的影响,确定了最佳的桥壳压制模具运动方式以及预制坯内部压强的大小,并进一步分析了理想桥壳成形件壁厚分布情况。模拟结果表明:汽车桥壳胀-压复合成形工艺压制过程中,当压制模具同时运动且预制坯内部压强为30 MPa时桥壳成形件的成形质量最佳。在最佳成形条件下,桥壳成形件中间壁厚最薄,最薄壁厚为3.2 mm且大于初始设计最薄厚度,桥壳的轮廓清晰、过渡圆角大小合适且没有破裂或飞边失效,满足汽车桥壳的设计要求与使用要求。     

42CrMo钢铸造环坯辗扩成形理论与工艺分析

与目前常用的环类零件生产工艺相比,基于环形铸坯的短流程铸辗复合成形新工艺具有节约材料和能源、缩短工艺流程等优点。以轴承环件常用的42CrMo钢为研究对象,探讨基于环形铸坯的轴承环件辗扩成形机理和工艺。借助于热力模拟试验和组织测试分析,揭示42CrMo钢在热变形条件下组织演变机理和规律;通过理论分析与数值模拟,研究铸坯环件辗扩成形过程中变形工艺参数及其对金属变形和组织演变规律的影响,实现环形零件铸辗复合成形/成性一体化调控;在洛阳LYC轴承股份有限公司,完成轴承套圈铸辗复合成形工业试验。试件的力学性能测试结果表明,这种短流程铸辗复合成形新工艺生产的环形零件具有良好的力学性能指标,可满足工业使用要求。     

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...     

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.     

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.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.