汽车轮毂轴承游隙分析及结构改进

通过对某汽车前轮毂总成中轴承游隙的分析,得到影响轴承游隙的主要因素,并对原有汽车前轮毂总成中轴承的结构进行改进。     

小盒商标纸在线压痕装置的设计与应用

目的 解决中支双铝包小盒商标纸因模切压痕不稳定出现的烟包小盒侧边弹开翻折、烟包变形等问题。方法 设计小盒商标纸在线压痕装置,该装置包括机架、传动轴、辗送轮、压痕件、导纸轮、对压轮、压痕避让部和托纸轮,同时开展正交试验,获取压痕件半径、刃缘弧长和包装机作业速度最佳参数组合。结果 应用在线压痕装置后,小盒商标纸压痕挺度的平均绝对误差由6.0减小至1.9,次品烟包频率由37.6包/班次降低至8.4包/班次,改进后比改进前降低了77.7%。结论 设计的小盒商标纸在线压痕装置可使商标纸挺度处于适宜水平,降低了该类缺陷烟包频率,提高了烟包包装质量。该技术可为提高双铝包包装机的产品质量、作业效率及稳定性提供支持。     

轴颈倾斜下船用复合衬层艉轴承混合润滑特性分析及结构优化EI北大核心CSCD

船用艉轴承支撑着悬伸于船外的螺旋桨轴,由于螺旋桨的重力作用,其轴颈中心线不再平行于轴承孔中心线,而是在竖直平面内发生倾斜。轴颈倾斜使轴承膜厚及压力沿轴向不再均匀分布,显著降低轴承承载能力,使之处于混合润滑状态,且易导致碰磨、严重磨损甚至轴瓦烧焦等问题,严重危害轴系服役安全。为提高轴颈倾斜下水润滑艉轴承的性能,改善压力分布,提出了一种采用复合衬层的轴承设计方法,以高分子材料作为承载表面,在高分子承载层与金属外壳之间加入橡胶层,橡胶层为等厚或非等厚结构。在此基础上建立了复合衬层水润滑轴承的混合润滑模型,分析了单一衬层结构、等厚复合衬层结构及非等厚复合衬层结构下的轴承性能。结果表明,对于处于混合润滑状态的水润滑轴承,复合衬层改善了压力分布、降低了摩擦因数和混合润滑状态过渡到流体动力润滑状态时的转速,而非等厚复合衬层对润滑性能具有更显著的改善作用。总结得到非等厚复合衬层轴承最优橡胶层厚的拟合公式,并给出了公式的适用范围,公式形式简洁,便于应用于轴承设计计算。相关工作为船用轴承优化设计和承载能力提升提供了新思路。     

新型涡轮式气启动马达的结构设计

针对工程车辆使用特点和发动机的配置需求,设计了一种新型涡轮式气启动马达,通过对单向器、齿轮推进装置以及连接装置等进行结构创新,避免了顶齿现象发生,且它具有体积小、强度高、传动可靠、寿命长以及小齿轮拆换方便等优点。动力总成设计采用双级冲击式涡轮转子,由2个定子和2个转子组成气道,提高了气体动能利用率。传动总成设计是在现有棘轮式单向器基础上加以改进,采用滚动摩擦和轴承支承结构,使得空气通过气路接口推动活塞轴向移动,减少了零件个数及摩擦。减速总成设计采用行星减速器,可实现极低速运转,同时具有质量轻、体积小、转矩和过载能力大、摩擦少且结构简单等优点。对该马达进行现场试验测试,试验结果表明,该结构与汽车发动机更为匹配,更能满足发动机启动要求,使机动车发动机顺利启动;其适应气源条件更宽,在无补气条件下可实现车辆多次启动,使得车辆气启动更为可靠。该新型气启动马达为发动机启动提供了一种选择,也对国内气动马达的发展起到了促进作用。     

(超)高速包装机 GDH1000 商标纸堵塞原因分析与改进

GDH1000 包装机运行过程中存在商标纸频繁堵塞、产生不合格烟包现象,严重影响设备运行和产品质量。为此,从商标纸模切、商标纸吸取交接等方面对问题进行了分析研究,对商标纸模切方式、商标纸吸取交接机构进行了改进:加大了商标纸切口宽度,整体式吸取器改为分离式,交接机构改为锯齿形交错机构。改进后商标纸堵塞次数大幅减少,产品包装质量和设备运行效率得到了提高。该改进方法对提升卷烟、食品、药品等产品的商标纸外包装质量有实际意义。     

机械计数器常见故障的维修

滚轮式机械计数机构广泛用于计量仪器中,如水表计数器、电度表计数器等。我们从实际工作中总结出机械计数器常见故障及维修方法: (1) 齿轮与字轮间有迟滞现象。应调整齿轮与字轮间隙,清洗轮上的脏物; (2) 轴被锈蚀。用细砂纸打磨除锈; (3) 字轮转动时摆动过大。主要是轴孔的磨损造成的,为此,字轮如果是塑料的,应更换字轮,若是金属轮孔则须修轮孔; (4) 齿形磨损或字轮残缺,须更换新的; (5) 字轮目前大都是塑料轮,因此易磨损,特别是第一个字轮(最低数位) 最易磨损。它与高一位字轮之间的两个拨齿损坏的最多,而一般单位都不可能有备用字轮,一旦损     

水泥混凝土道面结构在多轮荷载作用下的响应分析

为研究多轮荷载作用下对道面结构的响应,以ABAQUS分析软件为基础,采用多层结构的线弹性材料,建立了9块水泥混凝土面层板的"软弱地基-道面结构-飞机轮载相互作用"三维有限元模拟模型,建模过程中考虑了纵向横向接缝的传荷能力,为大型飞机轮载作用下的道面结构体系及其力学响应研究提供了先进、可靠的分析平台。     

基于空间轴承寿命预测的预紧力优化分析

以航天机构中的精密轴系为研究对象,构建了空间轴承寿命预测的数学模型,提出适宜于固体润滑轴承初始预紧力优化的方法,为其预紧力的设计和选择提供理论指导。基于滚动轴承的运动学、拟静力学和Archard磨损模型,综合考虑支撑刚度和润滑膜抗压极限强度要求,确定了预紧力的许用范围。以使用寿命最长为优化目标,优化了空间轴承71807C的初始预紧力。研究结果表明:空间轴承初始预紧力的选择范围为70 N~200 N;在磨损过程中,磨损深度和残余预紧力相互影响、相互作用;基于使用寿命最长的优化目标,优化得到156 N的初始预紧力为精密轴系组件的最优预紧力,并探究了不同预紧力下空间轴承的失效机理。     

一种便携式四轮定位仪校准装置的技术研究

文章通过对JJF 1154—2014 《四轮定位仪校准规范》的详细研究及现场试验,结合目前四轮定位仪校准装置在主销模拟、定位参数零位确定、现场安装等方面的不足,介绍一种四轮定位仪校准装置采用四轮分体、组合使用的结构,由步进电机作为角度驱动器,通过高精度双轴倾角仪及绝对角度编码器实现角度闭环系统控制。文章对该装置的结构设计及校准原理进行了深入阐述,以期为四轮定位仪校准技术发展起到些许参考。     

保持架间隙对角接触球轴承保持架磨损的影响研究

保持架间隙是滚动轴承重要的结构参数之一,直接影响着保持架受力和运动,进一步影响保持架的磨损甚至轴承的寿命。在分析轴承保持架间隙与受力关系的基础上,定性分析间隙对保持架磨损的影响;在搭建滚动轴承试验器上开展了保持架间隙对角接触球轴承保持架磨损影响的试验研究;在相同试验条件下对采用不同引导间隙和兜孔间隙保持架的被试轴承进行试验,分析了保持架和钢球表面形貌磨损特征,对比不同保持架间隙(引导间隙、兜孔间隙)条件下保持架与钢球的磨损程度,获得保持架间隙对角接触球轴承保持架磨损的影响规律。试验结果表明,保持架间隙明显影响着保持架兜孔、引导面的磨损,增加引导间隙及兜孔间隙可以降低保持架引导面的磨损;研究成果为保持架间隙的设计与优化提供了理论参考和试验依据。     

Variable Parameters PD Control and Stability of a High Rate Rigid Rotor-Journal Active Magnetic Bearing System

Stability is a key problem that means whether a high rate rotor-active magnetic bearings system works reliably or not. Aiming at a bearings system described with nonlinear equations, this paper built a linear model according to the system behavior. Considering realization of the control system and behavior of a high rate rotor system (magnetic force is far smaller than input force produced by mass eccentricity) this paper proposes a design method of variable parameters PD control algorithm that can be used universally. The control system was simplified and a mass of adjusting work of control parameters was reduced. Analysis and simulation indicated that the bearings system could get a wider stable region of harmonic motion, and proved that the algorithm is robust and advanced. The control system can be realized because the winding electric currents are positive. The method is convenient for operation and can easily be used for engineering practice.     

Hybrid approach for remaining useful life prediction of ball bearings

Remaining useful life (RUL) prediction plays an important role in predictive maintenance systems to support decision‐makers for arranging maintenance tasks and related resources. We propose a hybrid approach that is combined an exponential weighted moving average (EWMA) control chart for anomaly detection and machine learning models such as support vector regression (SVR) and random forest regression (RFR) with differential evolution (DE) algorithm to predict the RULs of ball bearings. Here, DE algorithm is used to find the optimal hyperparameters of SVR model. The datasets of ball bearings from the Prognostics Data Repository of NASA are used to compare the prediction performance of different methods. The degradation behavior of training data from the anomaly time to the end of life is used to transfer learning for the testing data in the SVR and RFR models. The results indicate that the proposed methods outperform the other four existing methods in terms of score. Therefore, the proposed hybrid approach is a reliable tool for the RUL prediction of ball bearings.     

高速防滑轴承异形外环滚道的精密磨削加工

针对高速防滑轴承的加工关键－外环非圆波瓣形滚道的加工问题，提出了一个有效的计算机控制磨削方案，介绍了解决的关键技术问题和实际加工结果。     

An investigation of rail bearing reliability under real conditions of use

The objective of the present work is to carry out a performance analysis of roller bearings used in railway ore transportation wagons. Data from 47,000 failed bearings divided in seven groups, were used to determine the failure distribution. Six groups corresponded to operation in the years 1985–1988, 1990, 1991 and one group included all the others. The failure distribution in bearings was described by the three parameter Weibull distribution. To conduct the statistical analysis it was necessary to estimate these parameters by the nonlinear regression method, because it does not require the whole group of failed bearings, and direct inference on the sample. A Monte Carlo technique was used to validate the procedure. Analytically two estimate methodologies were considered. Methodology I is a well established technique while Methodology II is an alternative approach proposed by the authors, which was inspired by a procedure used to design rail shafts. Studying the bearing failure behavior led to the following observations: based on sample inference techniques, an excessive variation was observed in the parameters that characterize the failure distribution. A dispersion of the order of 40 or 25% was found in the minimum and nominal lives when evaluated by the direct inference method or by the nonlinear regression method, respectively, and a dispersion of 17% calculated by nonlinear regression was observed for the shape parameter, . In spite of this dispersion, it was found that the minimum lives estimated by direct inference were conservative by a factor of four, when compared to analytical methods, while estimates of the nominal life were shown to be similar to its smallest value observed in the sample groups.     

实心和空心滚子结构阻尼的动态分析

结构阻尼是结构动力分析的重要参数之一,运用有限元方法研究实心和空心滚子在冲击载荷作用下的动态响应,并用傅立叶变换处理自由衰减中不同起点的两段相同长度的数据,求得滚子的结构阻尼,分析了滚子在不同冲击载荷、结构参数和材料参数下的阻尼特性。通过对滚子本身结构阻尼特性的研究,为轴承的振动研究提供了理论基础。     

硼／铝复合材料管构件的界面特性EI

主要研究带钛合金连接头硼／铝复合材料管构件中Ｂ－Ａｌ－Ｔｉ间的界面结构与性质。研究表明，在复合工艺条件下，硼－铝界面附近没有检测到任何铝－硼化合物，而钛－铝间形成ＴｉＡｌ有序金属间化合物相。实验证明，硼／铝复合材料与铝合金端环之间采用的固结方法是有效的，且可按照受载类型随意调整斜面搭接长度，达到承受不同载荷的目的。     

Comparative test on two kinds of new compliant foil bearing for small cryogenic turbo-expander

Two kinds of new compliant foil journal bearing for a small cryogenic turbo-expander used in the Brayton cycle cryocooler are presented in this paper. The foil of bearings is supported with copper wires and elastic material respectively, so the bearings are much simpler in structure than previous compliant foil bearing. The performances of the bearings are studied under the same experiment conditions. The results indicate that both bearings have better damp performance and the foil bearing supported with elastic material has preferable stability to the one supported with copper wires.     

A novel magnetic suspension cum linear actuator system forsatellite cryo coolers

Stirling cycle cryogenic coolers have been widely used for device cooling in satellites. Various types of magnetic bearings and linear actuators find application in such systems. The most widely used configurations have two-axis-radially-active suspension stations placed at either end of a reciprocating shaft in the compression and expansion sections. Separate or integral linear motors are provided in each section for axial shaft movement. It may be noted that such configurations are rather complicated and less reliable because of the presence of numerous electro-mechanical components, sensors and electronic servo channels. In this paper, a simple and reliable scheme is suggested which axially stabilizes and linearly perturbs the piston so that the need of a separate motor for axial actuation can be totally dispensed with. The piston is radially supported by passive repulsive bearings. In the axial direction, a servo actuator `balances' the piston and also actuates it bi-directionally. Implementation of this `bearing cum motor theme', reduces the number of electromechanical and electronic components required to operate the system and hence minimizes the chances of system failure. Apart from this, the system's power consumption is reduced and efficiency is improved as electrical heating losses caused by quiescent-operating currents are removed and electromagnetic losses on the moving parts are minimized. The necessary system parameters have been derived using finite element analysis techniques. Finally, the proposed design is validated by computer-aided system simulation     

不同板条形状对艉轴承的力学性能影响研究及其结构优化

 为了提高板条式艉轴承的润滑性能,应用有限元法研究不同板条形状对艉轴承力学性能的影响及其结构优化．具体探讨不同曲率半径凹弧型和凸弧型板条以及不同楔形空间承载面积板条的力学特性,将结构优化前后力学性能进行对比．结果表明：就3种不同形状板条而言,平板型板条的力学性能相对较好;不同曲率半径的凹弧型、凸弧型板条对艉轴承力学性能的影响规律有着较大差异;在不同楔形空间与单个板条承载面积之间存在应力最大、应变最小,力学性能相对最优的临界点;对平板型板条进行优化后,其力学特性有了明显的改善．     

风对隔震建筑物居住舒适度的影响

在时域上通过数值模拟分析,研究了顺风向和横风向脉动风荷载对基础隔震建筑物居住舒适度的影响。隔震系统包括叠层橡胶隔震器和铅阻尼器,叠层橡胶隔震器采用退化滞回模型进行分析,铅阻尼器则运用双线形模型分析其恢复力。基于脉动风速的多点自咽归模拟方法,根据功率谱函数和空间相关特性模拟脉动风力时程曲线。通过实例,研究了隔震建筑物风振响应特性,讨论了相关参数对振动特性的影响,为脉动风载下隔震建筑物的居住舒适度分析与计算提供了一个有效方法。