【作者】 周文；

【导师】 刘学毅；

【作者基本信息】 西南交通大学 ， 道路与铁道工程， 2008， 博士

【摘要】 高的平顺性是提高列车过岔速度、提高旅客乘坐舒适性及保障列车运行安全的基础,因此高速道岔对制造精度要求非常高。尖轨矫直是高速道岔生产的关键工艺环节之一,尖轨矫后线形对道岔的平顺性等制造精度影响较大,轨底残余应力影响尖轨的使用寿命。当前尖轨矫直仍停留在凭操作者经验进行粗放生产的水平,需多次反复才能矫直合格,返工率高,产品报废也时有发生,劳动强度大,效率低,而且达到高精度要求比较困难,影响高速道岔生产进度,增加产品成本。本文针对高速道岔尖轨的矫直特点,基于弹塑性理论,通过理论分析、有限元数值计算,对高速道岔尖轨矫直理论及相关关键技术进行研究,论文的主要研究工作如下:(1)尖轨矫直理论研究在分析压力矫直基础理论基础上,通过采用弹塑性理论,建立具有复杂断面特性的高速道岔尖轨矫直力学分析模型,对尖轨矫直的弹塑性区域分布、矫直应力、残余应力、尖轨矫直挠度及残余几何形态进行分析讨论,研究尖轨矫直机理,建立相应的计算公式。采用数值计算方法,通过编程求解尖轨不规则形状截面弹塑性区域分布方程、应力方程及挠度方程。(2)尖轨矫直有限元分析研究针对复杂结构构件,无法用解析法求解矫直参数的工程难题,采用弹塑性有限元法,建立尖轨矫直三维实体模型,对尖轨竖向矫直、横向矫直及曲线尖轨顶弯进行有限元分析计算,详细分析尖轨竖向矫直、横向矫直及曲线尖轨顶弯的线形变化、矫直应力和残余应力分布规律。结果表明,竖向矫直与横向矫直的线形变化、矫直应力和残余应力分布规律不同,横向矫直与顶弯的线形变化、矫直应力和残余应力分布规律比较相似。为验证本文采用的弹塑性有限元法及计算模型的正确性,进行尖轨矫直试验。结果表明,有限元计算结果与实验结果相差较小,本文采用的弹塑性有限元法及计算模型可用于尖轨矫直分析。(3)尖轨矫直关键参数研究加载支距和压弯量是尖轨矫直的两个关键矫直参数。分析不同加载支距及压弯量条件下尖轨的残余变形、矫直应力、残余应力和矫直力的变化规律。结果表明,残余变形、矫直应力、残余应力和矫直力随加载支距的增大而减小,随压弯量的增大而增大。(4)初始变形及矫直部位对尖轨矫直的影响研究分析尖轨在不同初始变形条件下矫后残余线形、矫直应力和残余应力。结果表明,不同初始变形尖轨在相同矫直参数条件下残余挠度、矫直应力及残余应力相差不大。尖轨不同弯曲方向矫后残余应力及线形变化不同。分析尖轨不同部位矫后残余线形、矫直应力和残余应力。结果表明,尖轨切削部位被削弱,抗弯模量变小,相同的压弯量所需矫直力减小,残余曲率、矫直应力及残余应力减小。(5)尖轨矫直工艺及矫直质量评价方法总结分析尖轨支点、压点组合的确定方法及原则。采用有限元方法,编程计算尖轨矫直及尖轨顶弯的压弯量。结果表明,给定尖轨初始曲率半径条件下,加载支距越大,所需压弯量也越大;相同加载支距下,初始曲率半径越大,所需压弯量越小。尖轨初始曲率半径越小,矫直后轨底残余拉应力越大;曲线尖轨顶弯时加载支距越大,所需压弯量也越大,但轨底最大残余拉应力相差不大。建立尖轨矫直质量评价方法,结合生产实际及高速道岔的技术要求,分析讨论尖轨矫直质量检测内容及检测方法,为高速道岔矫直质量评价提供指导。更多还原

【Abstract】 High smoothness is the basic of increasing train’s speed when passing through turnout,of improving the passengers’ comfort and of ensuring the train’s safety.So the manufacturing accuracy of high speed turnouts is very highly required.Straightening switch rail is one of key technology steps in manufacturing of high speed turnouts.The shape of straightened switch rail has a great influence on accuracy including turnout’ s smoothness etc.,and the residual stress has influence on service life of turnouts.At present straightening of switch rail remains at lower level,which mainly depends on workers’ experiences.To get qualified switch rail,the switch rail need to be straightened many times. The failed products don’ t meet the requirement of correction,often occur in the workshop.The working efficiency is low,and working inten -sity is great.These have influences on manufacturing progress,and will increase the manufacturing costs.According to characteristics of straightening switch rails,base on elastic-plastic theory,the theory and key technology in straightening switch rail of high speed turnouts are studied by theoretical analysis and FEM.The research work is divided into the following areas:(1)Study on theory of straightening switch railBase on the basic theory of press straightening,the force analysis model of straightening switch rail with complex section characteristics is established to analyze the regional distribution of elasticity -plasticity,straightening stress,residual stress,straightening defle -ction and residual geometric shape by using elastic-plastic theory. Mechanism of straightening switch rail is studied,and corresponding calculating formulae are built.The regional distribution of elasticity -plasticity equation,stress equation and deflection equation are solved by numerical method. (2) Simulation of straightening switch rail by FEMBecause calculating the parameters of straightening complex section components is impossible,the vertical straightening,lateral straighte -ning and bending are simulated by elastic-plastic FEM with three dimensional solid finite element.The geometric shape change,straighte -ning stress and residual stress are simulated in detail.The results show that the geometric shape change,the distribution of straightening stress and residual stress are different between vertical straightening and lateral straightening.The geometric shape change,the distribution of straightening stress and residual stress are similar between lateral straightening and bending.So the deformation processes of vertical straightening,lateral straightening and bending are different.Experiments on straightening switch rails are carried out to verify the elastic-plastic FEM and the calculate model.The results show that the discrepancy between FEM results and experiment results is small.The PEM and the calculate model can be used to simulate straightening switch rail.(3)Study on key process parameters of straightening switch railLoading distance and pressed bending amount are the two key process parameters of straightening.The change laws of residual geometric shape, straightening stress,residual stress and straightening force are analyz -ed with different loading distance and pressed bending amount.The results show that the residual geometric shape,straightening stress, residual stress and straightening force decrease with loading distance increasing,and increase with pressed bending amount increasing.(4)Study on effect of the initial deformation and straightening part in straightening switch railThe residual geometric shape,straightening stress and residual stress are analyzed in different initial deformation switch rails straightening.The results show that under the same parameters of straightening,the residual deflection,the straightening stress and residual stress differ little.The residual stress and shape change in different bending orientations are different.The residual geometric shape,straightening stress and residual stress are analyzed in different part of switch rails straightening. Because the bending modulus is small at cut part of switch rail,the straightening force,residual curvature,straightening stress and residual stress are smaller.(5)Study on technology of straightening switch rail and straightening quality evaluationThe determination way and principle of fulcrum and load action point were summarized and analyzed.The pressed bending amount in straightening and bending by FEM is calculated.The results show that the greater loading distance,the greater pressed bending amount at the same original bending radius.The greater original bending radius,the smaller pressed bending amount at the same loading distance.The greater residual stress, the greater original bending radius.The greater loading distance,the greater pressed bending amount in bending curve switch rail,but the residual stress of bottom differ little.The evaluation way of straightening switch rail is built.According to production practice and technical requirements of high speed turnouts, the inspecting content of straightening switch rail is analyzed and discussed.The way of inspecting various inspecting content is studied. The results can give reference for evaluating the quality of straighte -ning switch rail of high speed turnouts.更多还原