T型导轨压力弯曲变形及其校直工艺理论研究

发布时间：2018-01-11 16:36

本文关键词：T型导轨压力弯曲变形及其校直工艺理论研究　出处：《浙江大学》2014年博士论文　论文类型：学位论文

【摘要】：弯曲变形校直工艺过程是T型导轨切削加工流程中的最后环节,也提高导轨直线度的必然环节。精密自动校直设备的发展必然会催生和激发压力校直工艺理论方面的研究,而对校直工艺理论的研究必须要从导轨压弯过程的弹塑性弯曲回弹机理入手。因此,本论文分别基于弹塑性理论、实验研究、有限元模拟等方法对T型导轨的弯曲回弹特性进行了较为系统的研究,以此为基础对导轨反弯校直工艺理论进行了探讨。本文主要完成了以下工作：第一章介绍了本课题的研究背景和意义、压力弯曲及弯曲变形校直工艺理论及其相关领域的研究现状、存在的科学问题以及本文研究的主要内容等。第二章针对材料强化模型及强化特性参数对工件弯曲变形量的计算精度有着重要的影响,以弹塑性弯曲理论为基础对强化性金属T型导轨弯曲变形进行研究,建立了导轨回弹曲率、残留曲率关系的数学解析模型,在电子万能试验机上设计了T型导轨三点压弯实验。通过理论解析结果与实验数据的对比分析,探究了材料强化模型及强化参数的变化对导轨弯曲变形量的计算及高精度校直的影响。第三章载荷-挠度关系模型不仅可以反映导轨弯曲过程的弹性变形、弹塑性变形和卸载弹性回弹三个阶段,而且该模型提供了一种计算校直下压量的新方法,适合直接应用于压力校直控制系统。为此,本章基于弹塑性弯曲理论对T型导轨弯曲载荷-挠度关系模型展开分析,建立T型导轨加载变形阶段的载荷-挠度关系解析方程式,最后分别在电子万能试验机和自制的液压压弯校直机上进行实验以验证模型的准确性。第四章重点在于T型导轨弯曲变形特性的实验研究及有限元分析,将实验研究和有限元结合起来,首先以神经网络为媒介,根据实验数据建立导轨回弹量预测模型,研究了在一定的初始挠度下加载行程和回弹挠度之间的关系。同时,结合有限元模型研究材料特性参数对回弹量的影响,通过实验数据和有限元分析数据建立了材料特性参数神经网络识别模型,最后将导轨压弯回弹挠度的模拟结果与实验结果进行对比,以验证本章所建立的有限元模型。第五章针对T型电梯导轨属于高精度长导轨,弯曲变形形状通常比较复杂,可达两至三个弯曲弧度,需要分两段以上压弯校直,提出了一种长导轨逐段压弯及其校直弯曲模型,将导轨压力弯曲工艺的研究进一步扩展到多段压弯及其校直应用中。为要达到导轨逐段校直的目的,在此基础上进一步给出了一种导轨校直过程中压力头加载行程的计算方法。第六章为了研究T型导轨弯曲卸载后残余应力分布状态,本章分别对导轨水平方向对称弯曲和垂直方向非对称弯曲回弹后的残余应力进行分析,基于弹塑性弯曲理论推导出了导轨弯曲卸载后残余应力分布的解析表达式,同时还分析了压力卸载过程中发生反向屈服现象的可能性。第七章开发了一套集成机械、检测、自动控制、通信和计算机等多项技术为一体的导轨自动压弯校直控制系统,分别基于弹塑性弯曲理论、导轨压弯过程载荷-挠度关系模型和实验数据总结了三种计算校直加载行程的方法,以便集成到本课题所开发的控制系统中。
[Abstract]:Bending straightening process is the last link of processing flow of T rail cutting, also improve the inevitable link straightness. Development of precision automatic straightening equipment will bring and stimulate research pressure straightening technology theory and Research on straightening technology theory must be from the guide rail bending process of elastic-plastic bending springback starting with the mechanism. Therefore, this paper based on the elastic-plastic theory, experimental study, springback characteristic finite element simulation method of T type guide rail are studied systematically, based on the guide of anti bending straightening technology theory is discussed. This paper mainly completed the following work:
In the first chapter, we introduce the background and significance of this topic, the research status quo of pressure bending and bending deformation straightening technology and related fields, the existing scientific problems and the main contents of this research.
In the second chapter, the calculation precision material hardening model and strengthening characteristic parameters of bending deformation of the workpiece has an important impact on the elastic-plastic bending theory of reinforced metal T type bending deformation of guide rail, established the mathematical model of residual springback curvature, curvature relationship, the design of T type rail three point bending experiments on electronic universal testing machine. Through comparative analysis of theoretical analysis results and experimental data, to explore the change of material hardening model and strengthening parameters on rail deformation calculation and high precision straightening effect.
The third chapter load deflection relationship model can not only reflect the track bending process of elastic deformation, elastic-plastic deformation and unloading springback of three stages, and the model provides a new method to calculate straightening press amount, the pressure straightening control system suitable for direct application. For this, this chapter is based on elastic-plastic bending the theoretical analysis of T type guide rail bending load deflection relationship model, the establishment of T type guide rail loading deformation stage load deflection relationship analytic equation, finally the electronic universal testing machine and hydraulic bending straightening machine made by experiment to verify the accuracy of the model.
The fourth chapter focuses on the experimental study on the characteristics of T type guide rail bending deformation and finite element analysis, experimental study and finite element combined with neural network for the media, first of all, according to the prediction model of springback guide to establish experimental data, investigated the relationship between load and deflection in the rebound stroke under certain initial deflection. At the same time, influence on springback with a finite element study on the material properties of the model parameters, the material parameters of neural network identification model was established by experimental data and finite element analysis data, the guide rail bending deflection springback simulation results and the experimental results were compared to verify the established finite element model presented in this chapter.
The fifth chapter in the elevator T guide rail belongs to the high precision long rail shape bending deformation are usually more complex, up to two to three bending radian, need more than two section bending straightening, a long rail segment and straightening bending bending model, study guide pressure bending process is further extended to the bending and its application straightening multi segment. In order to reach the purpose of straightening rail sections, this paper introduces a calculation method of pressure head loading stroke a rail alignment process.
The sixth chapter to study the T type guide rail bending residual stress distribution, this chapter to guide the horizontal direction and vertical direction of non symmetric bending residual stress after bending springback symmetric analysis, elastic-plastic bending theory derived from the guide rail bending residual stress distribution analytic solution based on the analysis, but also the possibility of reverse pressure yielding phenomenon during unloading.
The seventh chapter has developed a set of integrated mechanical, detection, automatic control, rail communication and computer technology as one of the automatic bending straightening control system, based on the elastic-plastic bending theory, rail bending process of load deflection relationship model and the experimental data are summarized three methods of calculating straightening stroke load, so as to control integration the system developed in this paper.

【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU857

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