缓冲器设计计算

小松式压力机包括手工送料，全自动线，多工位压力机，其拉伸垫都设置行程上限缓冲器。本文介绍了手工送料压力机拉伸垫使用的缓冲器结构、工作过程、主要尺寸的确定、缓冲时间Ｔ的计算及温度－时间曲线的绘制，并对缓冲器使用油种的缓冲效果进行了比较，同时给出实例。     

列车套缸式液气缓冲器缓冲能量计算方法

本文提出了一种用于高速重载铁路车辆的套缸式液气缓冲器,在相同的缓冲器外形结构尺寸约束下,套缸式液气缓冲器比前后缸式液气缓冲器具有更大的缓冲能力。推导了这种套缸式液气缓冲器的缓冲能量和能量吸收率计算公式,分析了套缸式液气缓冲器内外缸之间的压力差、缓冲能量吸收率、内外缸强度、外缸初充气压力与节流孔径的关系,结合实际车辆连挂的要求,给出了套缸式液气缓冲器缓冲能量数值算例。     

新型芯轴式液压缓冲器设计与流场分析

针对传统液压缓冲器缓冲容量低、压力峰值大、缓冲不平稳等问题,提出一种新型的芯轴式液压缓冲器,并应用数值模拟的方法对该缓冲器进行流场分析。基于流体动力学理论,利用Fluent软件得到了缓冲器在初始状态下高压腔、低压腔和阻尼孔的压力及其差值的变化情况。改变螺距、槽宽和槽深等结构参数,得到了新型芯轴式液压缓冲器的压力及压差变化规律。结果表明:螺距对缓冲器缓冲特性有明显影响;槽宽和槽深对缓冲性能的影响取决于螺距的大小。     

液压缸:减轻冲击

为减轻高速液压缸行程终端所产生的冲击和噪声、缩短循环时间从而延长寿命,一般需要放置缓冲器。本文介绍了直柱形、锥形、阶梯形和笛形四种缓冲器的结构和原理,并分析了缓冲过程中四种缓冲器的特性。缓冲针形阀对缓冲压力、负加速度、末端速度影响最终端速度的选择,并用实例说明设计、选择缓冲器的方法。同时为更好地选用缓冲器,文中还介绍了缓冲压力的近似计算公式:P=(Wd P_2A_2-R)/A_1     

电梯用液压缓冲器的缓冲原理与结构分析

介绍了电梯中常用的液压缓冲器的类型结构和缓冲原理。结合流体力学基本原理和牛顿力学,建立了环状节流孔式液压缓冲器的分析模型,得到了节流面积-位移的函数,并进行简要分析,为渐变式节流式缓冲器的设计及缓冲特性研究提供参考。分析结果表明:节流杆的轮廓曲线以及节流孔的面积变化是影响缓冲特性的重要因素,是缓冲器设计优化的重点研究内容;要充分考虑安装空间、载荷撞击质量和撞击速度的参数情况来选用适合的缓冲器。     

基于AMESim的液压缓冲器主要结构参数的仿真分析

对液压缓冲器工作原理进行分析,在AMESim仿真环境下建立相应的液压缓冲器仿真模型。对不同缓冲活塞作用面积、环形配合缝隙宽度以及阻尼孔节流面积变化形式工况下缓冲器响应进行仿真研究,表明它们对缓冲器能量吸收效率以及缓冲平稳性的影响,为按工况进行缓冲器设计提供方案。     

胶泥缓冲器特性及其影响参数分析

通过分析双向胶泥缓冲器的特性,推导出胶泥缓冲器的综合特性公式,在代入相应设计参数后,得到了反映缓冲器特性的缓冲力和活塞运动速度关系曲线,并讨论了缓冲器结构、胶泥特性等参数对缓冲器特性的影响.     

基于六西格玛原理的导向筒生产质量的改进

针对某产品导向筒零件生产过程中存在的质量波动问题,运用六西格玛的DMAIC原理,并借助MINITAB统计软件,分析了导向筒零件质量波动的原因。结果表明,零件定位内孔尺寸和软氮化后外圆尺寸是影响导向筒零件生产质量的关键因素,控制导向筒零件定位内孔尺寸和外圆尺寸能够有效地提高导向筒零件的生产质量。     

渐变节流式液压缓冲器特性分析及优化

针对目前某型车辆渐变节流式液压缓冲器缓冲特性分析及结构优化的问题,提出了一种免疫算法优化缓冲器关键结构的方法。建立了某型车辆渐变节流式液压缓冲器数学模型,运用龙格-库塔法求解微分方程,得出缓冲特性曲线并分析不同参数对缓冲特性影响;基于此,以缓冲器缓冲效率为目标,以阻尼孔半径、长度及节流杆初始半径为优化变量,采用免疫算法进行结构优化。结果表明,优化后缓冲效率提升4%左右,最大缓冲力降低15.6%左右,最大缓冲行程增加15%左右,验证了该方法的有效性和高效性。     

油缸非调节形式前腔缓冲结构分析研究

目前挖掘机油缸前腔缓冲普遍采用导向套、缓冲套与节流孔组合的结构形式,通过调整导向套内置节流孔孔径确保缓冲性能达到设计要求。但该结构形式相对复杂,节流孔孔径较小,油液污染易导致堵塞而影响缓冲性能。因此,该文针对某型挖掘机油缸无节流孔非调节形式的导向套、缓冲套组合前腔缓冲结构开展研究。将缓冲结构划分为圆锥段缓冲、斜面段缓冲与末端缓冲三个阶段,结合缓冲压力测试曲线分析了节流孔孔径在三个阶段产生的影响。采用缓冲结构等节流面积原则,将缓冲套斜面设计为等效截面,并通过仿真分析验证了其对缓冲性能的影响。仿真结果表明:通过缓冲套斜面优化,可实现非调节形式的前腔缓冲,在简化缓冲结构的同时提高缓冲可靠性。仿真结果为该型油缸缓冲结构优化提供了参考。     

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...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

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.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

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....     

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.