新型滚切剪空间剪切机构优化数学模型的建立及应用

以纯滚动剪切为目标,通过对新型滚切剪空间剪切机构的原理分析,建立了增加导向杆为设计变量的剪切机构优化数学模型,以推广应用的某大型钢铁有限公司3000rm单轴双偏心定尺滚切剪的研发项目为依托,对剪切机构的杆件尺寸进行了优化,对运动轨迹进行了模拟。上下剪刃重叠量,刀弧水平偏移量,开口度的计算结果表明,加入导向杆设计变量的优化数学模型,对求得纯滚动剪切机构的杆件尺寸,降低刀弧水平位移量,均匀剪刃重叠量,保证设定开口度的作用显著。现场生产样机重叠量、刀弧水平综合位移量、开口度的实际值及高质量的钢板剪切断面也证实了上述优化数学模型的正确性。     

滚切式双边剪的修配改

滚切式双边剪是70年代初发展起来的一种新型中厚板剪切设备,因其弧形上刀刃在平直下刀刃上作滚动剪切．在剪切范围内刀片重叠量和剪切角几乎不变,被剪钢板两纵边的平行度好、接口错边量小、切口断面光滑、便于实现自动化,剪切效率高等优点,近年来国外新建或改建的现代化中厚板生产线广泛应用滚切式双边剪。     

滚切式定尺剪技术发展概述

介绍滚切式定尺剪几种剪切机构原理．     

对定尺剪设备的安装技术研究分析

定尺剪是中厚板轧机剪切线上的关键设备,主要用于钢板的定尺剪切。天津钢铁有限公司2#剪切线工程中定剪尺为滚切式定剪尺,本文主要介绍了滚切式定尺剪设备的安装调整技术及要领。     

滚切式双边剪剪切相关问题分析

随着社会经济和科学技术的发展,市场对于宽厚板的外观和质量要求也日益提高,而滚切式双边剪是确保宽厚板剪切平直、光滑和高精度生产的重要设备。本文主要概述了厚板厂滚切式双边剪,并分析了滚切式双边剪剪切的常见问题,并提出了提高双边剪剪切效率的对策。     

中厚板切边圆盘剪的设计与结构分析

本文利用计算机辅助系统,借鉴国外的先进技术,自主设计了国产化的中厚板切边圆盘剪,主要阐述了其结构特征及工作原理,并对主要结构件进行了参数制定分析,剪刃重叠量及侧隙对剪切质量的影响。     

滚切剪结构特点及应用前景分析

本文阐述了滚切剪的分类,论述了各类型滚切剪的用途、优缺点及适用条件,分析了滚切剪的工作原理,针对当前我国滚切式剪切机的特点,对其结构进行了分析,提出了其显著的结构特点,并论述了滚切剪在当前国内市场中的应用情况,对滚切剪的发展前景进行了展望。     

中厚板圆盘剪剪切力能参数测试及最佳剪刃间隙数学模型的建立

针对中厚板圆盘剪剪切质量差、剪切力理论计算偏差大等问题开展了生产实测、数据采集、回归拟合处理,得出现有的剪切力理论公式计算结果和实测结果相比误差在-9.56%～+56.5%之间.这些理论公式求解中未考虑随着厚度的增加剪切抗力和抗剪面积的非线性变化,导致剪切力计算结果大幅减小.这些公式适宜于薄规格钢板的剪切力计算,但用于厚板剪切力计算还要进一步完善.同时,建立了一个综合剪切钢板厚度、材料属性、累积剪切面积的圆盘剪剪刃间隙调整模型,并且考虑了刀盘装置在剪切受力过程中的变形对剪刃间隙影响.因此,针对不同的圆盘剪设备,要在该模型中考虑刀轴载荷-变形值的影响,对模型进行修正完善,就可获得适合于自己的间隙调整工艺参数.     

串联式球面剪叉机构的运动学建模与轨迹规划

目的研究一种用于球体表面装饰的串联式球面剪叉机构的运动学性能与轨迹规划。方法运用螺旋理论和修正的Kutzbach-Grübler公式计算机构的自由度,利用球面三角运算法则和坐标变换法,建立串联式球面剪叉机构的运动学模型,并采用Denavit-Hartenberg(D-H)四元数法对机构进行正运动学和逆运动学的求解,利用Matlab软件进行机构的工作空间求解,利用SolidWorks动态仿真法对机构进行轨迹规划,并进行运动性能分析。结果通过实例得出了机构在球面上按给定轨迹运行时的运动规律与实际规划轨迹的运动规律性能相符。结论串联式球面剪叉机构具有工作空间大、运动灵活、运动性能良好等优点,适用于在球体外包装表面上雕刻、喷绘以及其他相关应用领域。     

初始静剪应力下土与结构接触面静力特性研究

运用80t三维多功能土工试验机对粗粒土与结构接触面在一定初始静剪应力下的三维单调力学特性进行了试验研究。结果表明:接触面在不同剪切方向下均先剪缩后剪胀,剪胀主要在加载后期接触面接近和达到抗剪强度、切向位移较大时产生;接触面切向变形存在非共轴现象,切向位移增量方向随剪切的进行与切向应力逐渐靠近;切向位移间关系基本为直线,且其与初始静剪应力间的夹角和剪切方向角存在良好的数学关系;接触面抗剪强度包线基本为圆形,呈各向同性;剪切方向对接触面剪缩量、体变与切向位移关系、体变与切向应力关系及切向应力-应变关系有较大影响。     

Effect of friction on deformation during rolling as revealed by embedded pin technique

Abstract

The paper investigates the effects of friction on the heterogeneity of deformation during rolling through studies using plane strain (2D) and three-dimensional (3D) finite element models designed to simulate the deformation of the embedded pin inserts during rolling. Redundant work due to friction is defined as a path function along the arc of contact. Since deformation during rolling is profoundly influenced by the amount of redundant work, which depends on friction as a path function along the arc of contact, the study has focused especially on methods of representing these frictional effects. The friction studied has been in one of two classes: the coefficient of friction being constant or varying parabolically along the arc of contact. The results show that the values of shear stress and normal pressure along the arc of contact depend upon the friction profile. The magnitude of these frictional effects is revealed by the through thickness variation of the relative pin insert displacement. This displacement changes in the 3D model because transverse spread reduces the amount of displacement along the axial direction. Comparison of the simulations with experimental pin insert shapes shows close agreement between the predicted and experimental results, while revealing the direction of further work needed to provide suitable mechanics models to interpret experimental pin insert data.     

Free in-plane vibrations of curved nonuniform beams

Summary By introducing two physical parameters, the analysis of free in-plane vibrations of curved non-uniform beams is simplified. The explicit relations between the flexural displacement and the longitudinal displacement are derived. With these explicit relations, the two coupled governing differential equations are reduced to a complete sixth-order ordinary differential equation with variable coefficients in the longitudinal displacement, and a limiting study from the curved beam theory to the straight beam theory is successfully revealed. Finally, the influence of taper ratio, center angle and arc length on the first two natural frequencies of the beams is illustrated.     

基于ADAMS的IHI摆式飞剪剪切机构特性分析与优化

为探究IHI摆式飞剪剪切机构特性及优化方法,分析了IHI摆式飞剪剪切机构的结构组成和工作原理, 通过数值方法推导了剪切机构几何位置的解析法公式,计算出剪切机构初始位置.基于ADAMS动力学分析软件,建立飞剪剪切机构的机构杆件模型.仿真分析再现了飞剪的运动过程,得到剪切机构上、下剪刃的运动轨迹,速度变化曲线,剪刃开口度变化曲线和剪切过程中详细数据值.针对分析结果,利用ADAMS进行结构优化设计.优化结果改进了飞剪剪切过程中的速度超前和滞后问题,有利于剪切过程以及轧制工艺.基于ADAMS的分析方法与优化结果对IHI飞剪剪切机构的结构设计与改造具有实际运用价值.     

Interaction of shear waves with a griffith crack situated in an infinitely long elastic strip

This paper deals with the propagation of shear waves in a wave guide which is in the form of an infinite elastic strip with free lateral surfaces. This strip contains a Griffith crack. An integral transform method is used to find the solution of the equation of motion from the linear theory for a homogeneous, isotropic elastic material. This method reduces the problem into an integral equation. It has been observed that only shear waves with frequencies less than a parameter-value, depending on the width of the wave guide, can propagate. The integral equation is solved numerically for a range of values of wave frequency and the width of the strip. These solutions are used to calculate the dynamic stress intensity factor, displacement on the surface of the crack and crack energy. The results are shown graphically.     

弹性地基水平约束力的分析计算

基础梁由于混凝土受气温变化或收缩影响,常发生裂缝,使建筑物不能正常使用,因此,有必要计算产生裂缝的约束力。本文应用半空间体切向力作用于边界上的水平位移公式,计算单位切向力作用于矩形单元的水平位移ξ及其函数F。将梁分2n个等分单元,分段间隔为c,假定约束力在分段间隔c的长度内是均布的,采用结构力学混合法,利用梁和地基变形协调和力的平衡原理,建立联立方程式,求解温度变化或收缩引起未知约束力。为了简化计算,文后附有计算位移函数表。     

Transverse vibrations of prismatic rods by accounting for shears

Derivations of a differential equation of eight order and boundary conditions of flexural vibrations of a straight rod by accounting for shear strains caused by a transverse load are presented. Unlike existing approaches, use of coefficients of shear and angles of displacements is excluded in all relationships. The article gives the solution of the boundary-value problem on determining the function of plane displacement of sections with transverse shear for a round profile without the traditional introduction and additional determination of the shear function. An exact analytical solution of the boundary-value problem on free flexural vibrations of a cantilever rod by accounting for shears is presented. A numerical example of calculating flexural vibration parameters of a rod with round cross-sectional profile is examined along with evaluation of the effect of shear strain factor on frequency of the principal tone.Translated from Problemy Prochnosti, No. 2, pp. 82–86, February, 1991.     

分数阶微分双参数黏弹性地基矩形板动力响应

基于弹性地基Pasternak双参数模型,利用分数阶微分得到黏弹性地基双参数模型,并在此基础上建立采用分数阶微分Kelvin模型的双参数黏弹性地基上弹性和黏弹性矩形板在动荷载作用下的动力方程;利用Galerkin方法和分段处理的数值计算方法求解四边简支的弹性和黏弹性地基板的动力方程,通过自由振动算例验证该求解方法的正确性;并分析冲击动荷载作用下分数阶微分Kelvin模型的分数阶、粘滞系数、水平剪切系数和模量参数对位移响应的影响。结果表明：分数阶微分黏弹性模型可以描述不同黏弹性材料的力学行为;分数阶取值0.5前后,矩形板位移响应值出现了不同的衰减发展形态;粘滞系数、水平剪切系数和模量系数取值越大,位移响应衰减速度越快。     

瑞利波作用下双层地基中群桩横向动力响应

采用文克勒地基染模型建立了桩－土－桩相互作用的粘弹性模型,在现有的成层地基中瑞皮弥散曲线解析解的基础,瑞利波作用下的双桩横向相互作用因子^↑α的计算公式。利用Poulos的“叠加原理”,在双桩的基础上得出了群桩桩顶横向位移及桩顶剪力计算公式,经过一系列的参数分析,得出了瑞利波引起的“群桩效应”对于桩顶固接情况可以忽略而对于桩顶自由情况不能忽略的结论。     

The investigation of the nonlocal longitudinal stress waves with modified couple stress theory

In the present work, the propagation of longitudinal stress waves is investigated using a modified couple stress theory. The analysis of wave motion is based on a Love rod model including the effects of lateral deformation. The present analysis also considers the effect of shear stress components. By applying Hamilton??s principle, the explicit nonlocal elasticity solution is obtained, and the effects of shear stress and length scale parameter are discussed.     

滚动直线导轨副磨损特性和磨损机理试验研究

对国内外生产的45型滚动直线导轨副进行精度保持性对比试验,并对导轨副的精度保持性进行检测。基于Hertz接触理论和刚体动力学对滚珠和滚道的接触面进行了力学与变形分析,求出滚珠所受的最大接触应力,用Workbench进行仿真验证,为磨粒磨损机理和粘着磨损机理的研究提供参考。根据导轨副的运动工况和结构设计,使用场发射扫描电镜和白光干涉仪对上述试验后的导轨副的滚道和滚珠进行显微形貌观测,探究了导轨副的磨损特性和磨损机理。对比国内外滚动直线导轨副的滚道、滚珠的磨损程度,得出磨损是影响精度保持性的根本原因。