【作者】 邹国利；

【导师】 王黎钦；

【作者基本信息】 哈尔滨工业大学 ， 机械设计及理论， 2007， 硕士

【摘要】 FAST (Five-hundred-meter Aperture Spherical Telescope 500m射电望远镜)是1994年中国天文学家准备在贵州喀斯特地形上建造的世界上最大的主动反射球面射电望远镜。主动变形反射面是FAST主要创新点之一,中国天文界公认整体索网支撑是作为大射电望远镜(FAST)主动反射面的最佳支承结构。随动关节是整体索网结构实现主动反射的关键部件之一,对FAST主动反射精度及运动灵活性起着举足轻重的作用。本文首先考虑整体索网支撑结构的特点以及FAST主动反射运动要求,采用直线导轨和球面关节轴承组合的形式,设计了一种新型随动关节结构,它具有体积小、重量轻、结构紧凑、强度高、刚度大、便于安装、环境适应能力强等特点。并对随动关节的关键零部件进行了静力学分析和承载性能分析,为随动关节的设计提供了重要的参数指标。FAST反射面的每个面板都是三自由度的并联机构,基于空间并联机构理论,对随动关节进行了运动学分析,求出了面板单元质心位置的正解和逆解,从而得出了整体索网支撑结构径向拉索长度和面板质心位置关系;计算出了整体索网结构运动到极限位置时,随动关节直线导轨的移动距离,由此得到了面板单元的安装间距;进一步求出了径向拉索长度变化和面板质心速度之间的关系。然后通过SolidWorks软件和ADAMS软件进行仿真,对运动学推导结果进行验证。针对低速重载的工况,设计并制造了直线滑动轴承往复实验台,最大载荷为325kg,平均线速度范围为0.005m/s~0.12m/s。测试了几种直线滑动轴承在此工况下的摩擦学特性。实验结果显示,PTFE+石墨复合轴承在脂润滑条件下摩擦系数为0.09左右,运行平稳,满足随动关节低速重载工况的要求。更多还原

【Abstract】 FAST (Five-hundred-meter Aperture Spherical Telescope) is the biggestradio telescope with active spherical main reflector which was built in Karstterrain in Guizhou in 1994. The whole cable-mesh sustentation is acknowledgedas the best support of the active spherical reflector by astronomical group ofChina. Tracking joint is one of the key parts for the whole cable-mesh to reflectactively，which is very important to the precision and flexibility of FAST.Considering the characteristics of whole cable-mesh structure and themovement demand of active reflector, a new tracking joint was designed. Itsstructure assembles linear bearing and spherical joint bearing, so that it has manyadvantages, such as small volume, little weight, compact structure, high strengthand stiffness, easy to be install and good TadaptabilityT to eTnvironment, etc. Thestatic characteristics and bearing capacity of TprimaryT parts of were analyzed,which provides the important parameters for the optimization of Ttracking joints.Each panel of FAST reflector is a 3T-DOF parallel mechanism. Based on thetheory of spatial parallel mechanism, the kinematics analysis of the trackingmechanism was done. The Tdirect solution and inverse solution of center of panelmass Twere obtainedT. The relations between radial cable length of cable-meshstructure and the position of center of panel mass were obtained. The movingdistance of linear leader of the tracking joint was figured out, when cable-meshmoving to the ultimate position. So the installation distance among panels wasobtained. The relations between the length variety of radial cable and the velocityof center of panel mass were obtained. The analysis model was established bySolidWorks. And the simulation was carried out with ADAMS. The correctnessof the kinematics calculation was verified.Aimed at the working conditions of linear sliding under bearings low-speedand high-load, a reciprocating test bench was designed and manufactured. Itsmaximum load is 325kg and average linear velocity is from 0.005m/s to 0.12m/s.The tribological properties of four kinds of linear bearing were tested. Resultsshow the friction coefficient of PTFE+graphite bearings lubricated by grease isabout 0.09, and operates steadily. It meets the demand of tracking joints under low-speed and high-load.更多还原