高速电主轴冷却水参数对其温度场的影响研究

以COMSOL Multiphysics有限元分析软件为工具,建立170SD30-SY型电主轴水冷系统有限元模型,并对不同水流量下水冷系统温度场进行仿真;搭建水冷系统温升实验平台,分别对不同转速下的电主轴水冷却系统参数与电主轴温度的关系进行实验。研究结果表明:不同转速下,随着冷却水流量的增加,电主轴温度有不同程度的降低;冷却水流量为0.28 m~3/h~0.30 m~3/h时,冷却效果均为最佳选择;同时,通过改变冷却水初始温度来控制电主轴温升具有更直接效果。     

冷却水道宽度对陶瓷电主轴温升的影响研究

为了优化电主轴冷却系统,寻找环形冷却水道的最佳宽度,对170SD30-SY陶瓷电主轴实物进行了研究,以耦合传热数值计算理论为基础,利用软件ANSYS CFX对电主轴水冷系统中的流体流动和温度分布进行三维仿真计算,分析了具有环形冷却水道的电主轴冷却系统中,不同的冷却水道宽度对电主轴温度的影响。对比了水套与冷却水的温度与冷却水道宽度的关系。研究表明:冷却水入口速度一定时,随着冷却水道宽度的增加,冷却水流动走向由双向变为单向,电主轴温度先降低后升高;当水道内径为136mm时,冷却水道设计的最佳宽度为4mm。     

基于热变形分析的液体静压电主轴系统参数优化

液体静压电主轴系统的热变形严重影响机床加工精度,有必要对电主轴系统热变形的影响因素进行分析,以减小系统的热变形量。利用有限元法,分析在工艺参数和结构参数不同取值条件下某液体静压电主轴系统的热变形情况,重点分析冷却水流量、轴承供油压力、主轴转速、轴承结构参数对主轴热变形的影响。结果表明,电主轴系统的最大变形出现在主轴前端安装砂轮处;冷却水流量和供油压力的改变对主轴前端面径向最大热变形的影响规律显示,当冷却水流量和供油压力达到一定值时,系统的热变形已得到有效控制,若再增大冷却水流量和供油压力,热变形量减少的幅度较小;在不同的主轴转速下,润滑油的流动状态不同,润滑油在紊流条件下的主轴前端面径向最大热变形超过层流条件下的2倍。运用均匀设计试验,得到轴承长径比和轴承轴向封油边长度的优化参数值,使主轴前端面径向最大热变形控制为最小。     

高速电主轴角接触球轴承热-力耦合特性研究

在高速电主轴转子系统中,角接触球轴承的工作特性受温升的影响显著,极易产生胶合。为了得到更加精确的角接触球轴承瞬态温度场,建立了考虑自旋的角接触球轴承生热及传热模型,并利用MATLAB软件得到了轴承的生热量,随后建立了轴承的三维参数化模型,并基于显示动力学理论在LS-DYNA平台上进行了热-力耦合有限元仿真分析,且对影响轴承瞬态温度场的主要因素进行了研究。研究结果表明：转速与温升呈非线性正相关;高转速下轴承温升对预紧力更加敏感;生热量随预紧力的增加逐渐增大,当施加的预紧力大于最小预紧力时,温升随预紧力增加而变大。研究可为高速电主轴轴承的设计和稳定性分析提供理论参考。     

晶闸管水冷散热器的热仿真与实验

为协调散热性能与流动阻力的矛盾关系,开发了一款基于阿基米德螺旋流道结构的晶闸管水冷散热器。分别利用Hyper Mesh和FLUENT软件划分高质量网格与求解计算,得到了流速分布与温度场分布,可以看出冷却水在水冷散热器中间部位出现流速不均,导致中心部位的温度最高。通过分析冷却水流量、温度和发热量等因素对温升与压降的影响可知:入口流量不变时,温升随发热量增大而提高;发热量不变时,温升随入口流量增大而降低,流量增大至一定程度,温升受入口流量的影响很小;入口流量不变时,温升随冷却水温度升高略有下降;压降随入口流量增大而急剧上升;压降随冷却水温度提高而小幅度下降。建立了样品测试环境,测量了不同入口流量下的试验数据,对比分析可知仿真结果的准确性。对水冷散热器中间部位的流道进行改进后,最高温度降低了7.8%。     

牵引电机冷却系统流固耦合传热分析

牵引电机功率大、损耗大、散热空间小,保证其良好的冷却散热性能是车辆安全运行的重要保障。建立牵引电机冷却系统流固耦合传热仿真模型,结合牵引电机冷却水道评价指标,分析冷却系统流体场与固体场相互耦合的传热过程,分析冷却系统流场对电机内部温度场的影响,研究冷却液、电机损耗、入口温度、水道宽度等对温度场的影响。结果可知:冷却液流量的增大可以有效降低电机温升,电机绕组损耗对电机温升的影响远大于电机定子损耗对电机温升的影响;水道宽度在18mm时冷却结果最优。搭建牵引电机温升试验平台,分析电机损耗、电机内温度、冷却系统的温度等,获得冷却系统对牵引电机温升的影响规律,并与模拟值进行对比,从而验证了仿真模拟的准确性,分析结果可以作为设计参考的依据。     

热效应和弹性变形耦合条件下浮环轴承润滑静特性

当浮环轴承转子系统高速旋转时,油膜温升和浮环弹性变形是不可避免的。为研究油膜温升和浮环弹性变形对浮环轴承润滑静特性的影响,建立浮环轴承热流体动力润滑模型,利用数值差分法联立求解雷诺方程、能量方程、Rolelands黏温方程、浮环弹性变形方程和内外油膜膜厚方程,将油膜压力场、温度场和浮环弹性变形进行耦合分析,得到热效应和浮环弹性变形耦合影响下的油膜温升和浮环弹性变形量。结果表明:浮环轴承内外油膜温升和浮环弹性变形量随着偏心率的增加都逐渐增大;浮环弹性变形降低了内油膜温升,增加了外油膜温升;油膜温升降低了浮环弹性变形量;在耦合条件下内外油膜承载力、端泄流量和摩擦功耗均降低。     

高速电主轴系统的温升控制

文中阐述了高速电主轴系统在高档数控机床应用中的温升控制方法,着重就温升产生的原因进行分析：对电主轴系统温升的控制方法进行详细论述。结合生产实践中,对日本FANUC公司生产的高速电主轴在高速数控车床上进行成功应用,验证了文中介绍的电主轴系统温升的控制方法是有效,可行的。     

基于ANSYS的电主轴温度场仿真及分析

使用ANSYS对电主轴建立模型,并对其进行仿真.讨论各个热源、热扩散对电主轴温升的影响,并讨论了冷却液流量及压缩空气流量对电动机转子、前后轴承温升的影响,为控制电主轴发热提供了依据.     

电机控制器IGBT模块水冷散热设计

以电机控制器中IGBT模块水冷散热回路为研究对象,根据传热机理对其进行了传热与流阻分析;并利用有限元仿真模拟软件对水冷散回路的散热性能进行仿真模拟,研究不同翅片尺寸、翅片数量、冷却水流量参数对IGBT散热结温与冷却水压降的影响规律,获得了水冷散热的最优设计参数。结果表明:当冷却水流量为16 L/min、翅片数量为108、翅片尺寸为23 mm×6 mm时,水冷散热系统具有更好的散热效果。     

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。     

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.     

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....