基于ANSYS钢背铜塑3层复合材料端面轴承温度场分析

利用传热学、摩擦学和有限元的基本原理,建立了具有摩擦生热的聚甲醛钢背铜塑3层复合材料端面轴承的二维稳态热传导数学模型.应用ANSYS软件分析了端面轴承的稳态温度场.通过改变载荷、转速和表层材料厚度计算了复合材料端面轴承的最高温度.结果表明,端面轴承最高温度随载荷、转速、表层材料厚度的增加而升高,为研究钢背铜塑多层复合材料热影响提供了参考依据.     

钢背复合材料轴瓦的应用

钢背复合材料已应用到我厂开放式炼胶机轴瓦上,它代替了贵重的有色金属铜,价格既便宜,安装又方便。其结构是以钢板为基体,以烧结球形青铜粉为中间层,以塑料为摩擦表面层,并能牢固结合为一体的三层结构自润滑材料,如图1。钢背的作用是提供机械强度;多孔青铜是塑料与钢背结合的媒介,同时起到传导摩擦热、增加尺寸稳定性的作用;塑料表面层提供了良好的自润滑和摩擦磨损性能。钢背复合材料是兼有金属和塑料两种材料的优点,有较高的强度,良好的自润滑性能,及尺寸稳定性的新型轴承材料。     

钢背—铜基自润滑减摩材料干摩擦磨损性能的研究

对研制的三种钢背－铜基自润滑减摩擦材料进行了干摩擦条件下的摩磨损研究，并与常用的减摩材料６－６－３锡表铜作了对经经试验，用扫描电子显微镜对磨面进行了分析。研究表明，所研制的自润滑材料比锡表铜具有更好的减摩性。     

基于动态数据的端面摩擦热-力耦合分析

为了更加准确地探索端面摩擦过程中的温度分布情况,使用端面摩擦过程中的实时动态摩擦因数和红外探头实测温度作为边界条件,在多场耦合软件COMSOL Multiphysics中进行热-力直接耦合分析,并利用红外热像仪对计算结果进行检验。结果表明:实时边界条件与数值计算相结合的方法可以准确地模拟出端面摩擦瞬态温度场;摩擦副之间的转速、载荷、摩擦因数是影响温度场分布的主要因素。     

基于面接触的粉末润滑实验研究

利用石墨粉末颗粒,基于端面摩擦试验机对粉末润滑方式开展了摩擦学研究。试验了粉末冶金铜合金材料、粘结石墨润滑涂层、PTFE 3层自润滑复合材料3种试样在石墨粉末颗粒流润滑条件下的摩擦因数、温度及表面膜等特性,并与干摩擦和油润滑进行了对比。结果表明:粉末润滑可以实现与固体润滑膜、自润滑材料类似的无油固体润滑效果;利用它的持续补充性,可以实现动态补充和修复的固体润滑膜;但是,粉末润滑膜与基体附着能力较差。     

纤维编织自润滑衬垫的温度场数值模拟

以自润滑关节轴承中的纤维编织衬垫为研究对象,采用有限元数值模拟与试样温度测量实验相结合的方式,建立了纤维编织复合自润滑衬垫试验温度场的有限元模型,并对试样在不同工况条件下的温升过程进行了有限元模拟,为自润滑关节轴承衬垫的性能评价和温度场模拟提供了理论基础和试验依据。     

无油润滑涡旋压缩机自润滑的研究

无油润滑涡旋压缩机工作过程中相对运动的工作表面因摩擦而产生了功率损失,同时局部造成大量气体介质的泄漏,严重影响了工作性能。通过分析无油润滑涡旋压缩机的工作过程,针对各摩擦部位的特点,提出涡旋齿端面、支架体端面的磨合面加由自润滑材料制成的密封条,防自转机构的摩擦副的运动由直线式改为旋转式,同时曲轴的轴承采用自润滑形式等实现无油自润滑的技术关键。结果表明:密封条可以实现对运动表面的密封、润滑功能,防自传机构旋转式摩擦副降低了实现自润滑的技术难度,自润滑轴承工作性能优良,经济可靠,这些技术可以实现无油润滑涡旋压缩机的自润滑。     

铁基镶嵌轴承摩擦磨损性能比较研究

在端面摩擦磨损试验机上对45钢、铸铁、不锈钢镶嵌轴承试样进行了常温下干摩擦对比实验,探讨了不同铁合金基体对镶嵌轴承摩擦磨损性能的影响。结果表明,在载荷较大时不锈钢镶嵌轴承表现出了较好的摩擦磨损性能,45钢镶嵌轴承在载荷较小时其摩擦性能较好,但在各载荷下45钢镶嵌轴承的耐磨性都较差。     

机械端面密封计算技术

本文综述了机械密封密封环温度场,密封环变形和密封端面摩擦润滑计算技术的国内外研究现状,介绍了常用的计算方法,并比较了它们的优缺点,指出采用有限元法计算机械密封密封环温度场和变形效果较好,机械密封端面摩擦润滑问题计算的关键是建立合理机械密封摩擦特性模型。     

磨损时间对金属磨损自修复的影响及机理分析

利用MMU-5G型端面摩擦磨损试验机,研究不同磨损时间对45钢－45钢摩擦副磨损表面自修复膜生成的影响及其机理,借助KYKY-2800型扫描电子显微镜测试分析摩擦副的表面和自修复层形貌及表面成分组成。结果表明,磨损时间对添加剂在磨损表面形成自修复膜影响显著;摩擦磨损时间为24h时,试样失重为零,试样磨损表面自修复膜生成;自修复膜的生成使得试样摩擦磨损表面平整光滑,可以有效降低金属磨损。     

TEHD Analysis for Tilting-Pad Journal Bearings Using Upwind Finite Element Method

A general approach for incorporating heat transfer and elastic deformation effects into a tilting-pad journal bearing simulation model is presented. A global analysis method is used, which includes variable viscosity and heat transfer effects in the fluid film, elastic deformation and heat conduction effects in the pads, and elastic deformation effect in the pivots. The two-dimensional variable viscosity. Reynolds equation produces pressure distributions in the axial and circumferential directions. The energy equation is two-dimensional, assuming that the temperature variation in the axial direction is negligible. The elasticity and heat conduction models are also two-dimensional, being in the midline cross-section of the bearing, including the circumferential and cross-film directions. An upwind technique is used in the finite element formulation of the energy equation to remove numerical instability due to the convective term. Simulation results are compared with the test and predicted values of previous researchers.     

A Comparison of Four Solution Methods for the Analysis of a Trapezoidal Fin

A comparison is made of the temperature profile and the heat loss from a trapezoidal fin using four methods. These four methods are the one- and two-dimensional analytical, the two-dimensional finite difference and a two-dimensional modified finite difference method. The two-dimensional analytical method was arbitrarily chosen as the reference. The non-dimensional fin length is restricted to be less than 2 to prevent errors which might occur due to large values of Δx in the finite difference methods. The values of the Biot number range from 0.01 to 1.0 while the thermal conductivity of the fin and fin’s convection coefficients are assumed constant. The results show that (1) in the view of the heat loss from the trapezoidal fin, all four methods can be used to obtain the solutions within 3% with each other for the given range of Biot number and the non-dimensional fin length, (2) for the non-dimensional temperature, the one-dimensional analytical method does not produce good results as compared to the other three methods when the Biot number is 1.0, and (3) by using a two-dimensional modified finite difference method instead of the two-dimensional finite difference method, the relative difference in the heat loss as compared to a two-dimensional analytical method is reduced considerably.     

复合恒温构件热变形控制技术研究

研究了复合恒温构件在机床热变形控制中的应用,在分析相变热传导的基础上,研究了包含相变过程的二维传热特性,利用自适应变网格有限方法计算相变材料复合恒温构件机床立柱及主轴箱的温度场和热变形值,并将之与实测值比较,二者基本吻合。试验结果对精密数控机床热变形控制具有一定的参考价值。     

Shape optimization of two-dimensional thermal conducting solid using boundary integral equation formulation

A method for shape design sensitivity analysis of two-dimensional thermal conducting solid is presented using the material derivative concept and the adjoint variable method. A general thermal boundary condition with heat convection is considered in addition to prescribed temperature and heat flux. The method for deriving the sensitivity formula is based on standard direct boundary integral equation formulation. The sensitivity of a general functional depending on temperature and heat flux is considered. The method is then applied to obtain the sensitivity analysis is demonstrated by a hollow cylinder problem with exact solution. A weight minimization problem of a thermal diffuser is considered as a practical application. The sensitivity by the presented method is compared with that by finite differences and an optimal shape is found by use of an optimization routine.     

Thermal investigation of an infrared reflow oven with a convection fan

A two-dimensional numerical model for an infrared reflow soldering with a convection fan is used my modifying the Eftychiou’s numerical modeling. The two-dimensional tunnel model which predicts convective conditions within the reflow oven are solved using the finite volume method with the SIMPLER algorithm. The card model solves the transient two-dimensional heat conduction equation in conjunction with a radiative heat transfer analysis. We also performed an experiment to validate the numerical modeling. The numerical result shows excellent agreement with experimental data. Based on the capability of this model, parametric simulations are performed to determine the thermal response of the solder to variations in the oven operating conditions and heat transfer conditions. This study shows that radiation and conveyor velocity are important factors in the preheat region.     

核主泵用流体动压型机械密封温度场的数值研究

考虑流体粘温效应,建立了典型核主泵用流体动压型机械密封三维稳态传热有限元模型。建立了由流体域及密封环组成的二维轴对称共轭传热有限元模型,计算了对流换热系数。在此基础上,采用有限元软件求解三维模型密封温度,分析了流体入口流速以及转速对密封端面温度的影响。结果表明:深槽结构导致开槽静环密封端面温度分布不均匀;流体入口速度几乎不影响温度分布;增大转速,密封端面温度显著升高。     

换热边界下变物性梯度功能材料板瞬态热应力

用有限元和有限差分法,分析了由ZrO2 和Ti-6Al-4V组成的变物性梯度功能材料板的瞬态热应力问题,检验了方法的正确性,给出了对流换热边界下变物性梯度功能材料板的瞬态热应力场分布,并与不考虑变物性时的结果进行了比较。结果表明：在计算瞬态热应力场分布时,变物性是影响梯度功能材料板瞬态热应力场的最重要因素之一。此外,材料组分的分布形状系数 M、环境介质温度和对流换热系数的变化对变物性梯度功能材料板的瞬态热应力场分布均有明显的影响。此结果为梯度功能材料的设计和应用提供了理论计算依据。     

轴连轴承温度场分析

在对热传递方式分析的基础上,建立轴连轴承热传递模型.针对轴连轴承组件的具体工况及结构特点,并结合轴连轴承热传递模型,用有限差分法的思想将轴连轴承系统离散为一组温度节点.在球轴承拟静力学和生热分析的基础上,计算轴连轴承各组件的摩擦生热,轴连轴承组件各单元间摩擦生成的热量可近似按一定比例分配给内、外套圈.建立各个节点的能量...     

A numerical model for simulating temperature and speed effects in hot extrusion of rod

In this paper, a two-dimensional numerical model with upper-bound coupled thermal analysis has been developed. The model is capable of simulating the hot rod extrusion process with variable ram speeds. The temperature distributions and the speed effects in hot extrusion are predicted in detail by the proposed numerical model. A generalized kinematically-admissible velocity field without velocity discontinuity is adopted. The temperatures are calculated by considering simultaneously the heat generation due to deformation and friction and heat transfer. A finite-difference method with an implicit time integration scheme is utilized to solve the two-dimensional heat conduction problem. Two mathematical models for variable ram speed profiles are proposd. Ram speed profiles satisfying the exit temperature and the load requirements are obtained. The proposed numerical simulation has been demonstrated to be a powerful tool for the design of hot extrusion processes.     

Thermal analysis of the hydrostatic spindle system by the finite volume element method

The temperature rise of an ultra-precision machine tool has a great impact on machining accuracy. Meanwhile, the hydrostatic spindle system is the main internal heat source of the machine tool, which consists of a hydrostatic spindle and a direct current motor. Therefore, it is very significant to study the thermal behaviors of the hydrostatic spindle system. In this paper, an integrated heat-fluid–solid coupling model of the hydrostatic spindle system is built to simulate the heat generation process and the fluid–structure conjugate heat transfer. Then a finite volume element method (FVEM) is proposed by combining the advantages of the finite volume method (FVM) and the finite element method (FEM) with consideration of the interaction of the temperature field, thermal deformation, and eccentricity. Based on the proposed model and method, the thermal characteristics of the hydrostatic spindle system are studied by the two-way heat-fluid–solid coupling analysis. The temperature variations obtained by the simulation agree well with the experimental results, which validate the proposed model and method.