曲柄飞剪机设计分析与改进

施罗曼K型曲柄飞剪具有剪切速度高、剪切长度精确、结构紧凑等优点。由于设计上的缺陷,4台飞剪先后发生了上下刀架开裂、曲轴断裂、曲柄半径调节机构失灵和严重漏油等事故。本文分析了飞剪设计上的缺陷,并介绍了改造的方法。     

组合式飞剪剪臂优化设计

组合飞剪的特点是剪切机构即可以在曲柄模式下工作、也可以在回转模式下工作,在棒材生产线中应用比较广泛。但曲柄模式向回转模式转换时由于曲柄轴与剪头固定销轴之间接触面积小、冲击大而容易损坏。曲柄轴损坏后需要飞剪开箱更换,用时较长。针对此问题对组合式飞剪剪臂进行了优化设计改造,从而避免了因曲柄轴损坏造成的长时间设备停机。     

曲柄式飞剪高温剪切过程的数值模拟

分析了采用经验公式或实验方法获得剪切力和剪切功的缺陷和难度,提出采用金属韧性断裂研究飞剪高温剪切过程的方法,对此开展了曲柄式飞剪的剪切过程与金属韧性断裂过程的对比分析,确定了金属韧性断裂在剪切模拟上的可行性。在此基础上,探讨了金属韧性断裂模拟剪切的流程,并以某钢为例,开展了大量的实验研究,确定了材料的本构模型、高温剪切下的断裂准则和断裂因子,模拟了曲柄式飞剪在高温下的剪切过程,最终获得了剪切过程中的剪切力和剪切功历程,为曲柄式飞剪的传动计算和结构设计提供基础数据。     

热连轧曲柄连杆式飞剪设计探讨

简要介绍了曲柄连杆式飞剪的应用发展现状,重点探讨了热连轧曲柄连杆式飞剪设计的三个关键点:剪切机构的确定、优化与运动学分析,简述了用ADAMS软件对剪切机构进行运动学分析方法;剪切力的计算;飞剪系统的飞轮矩GD2的求解。通过讨论,为热连轧曲柄连杆式飞剪设计研究提供一些思路和方法。     

曲柄式剪板机剪切机构运动特性分析

把曲柄式切头飞剪剪切机构的杆件简化成曲柄四连杆机构,通过对杆件结构在工作过程中的位移变化,得到曲柄式切头飞剪的剪刃运动轨迹为一椭圆形结构,这对提高曲柄式切头飞剪机的效率具有重要的作用。     

热连轧曲柄式飞剪传动系统的设计与优化

从热连轧曲柄式飞剪的应用发展和需求现状出发,以设计研究的角度阐述了曲柄式飞剪传动系统的设计过程。系统探讨了曲柄式飞剪设计的核心内容——传动系统的设计和优化,详细论述了剪切机构的设计和优化、剪切力和剪切功、传动系统转动惯量、剪切过程中的能量转化模型等各关键点和难点,重点研究了曲柄式飞剪传动系统在设计优化上有别于其他飞剪的独特之处,如剪切力的精细化计算、传动系统各部分转动惯量的分布及优化等,指出了曲柄式飞剪在剪切过程中速度降幅的误区,并提出了传动系统参数匹配合理与否的判据,为曲柄式飞剪的传动系统设计提供参考。在此基础上优化传动系统参数并与实际工程进行了验证,结果非常吻合。     

热连轧曲柄式飞剪传动系统的设计与优化

本文从热连轧曲柄式飞剪的应用发展和需求现状出发,以设计研究的角度阐述了曲柄式飞剪传动系统的设计过程。系统探讨了曲柄式飞剪设计的核心内容——传动系统的设计和优化,详细论述了剪切机构的设计和优化、剪切力和剪切功、传动系统转动惯量、剪切过程中的能量转化模型等各关键点和难点,重点研究了曲柄式飞剪传动系统在设计优化上有别于其他飞剪的独特之处,如剪切力的精细化计算、传动系统各部分转动惯量的分布及优化等,指出了曲柄式飞剪在剪切过程中速度降幅的误区,并提出了传动系统参数匹配合理与否的判据,为曲柄式飞剪的传动系统设计提供参考。在此基础上优化传动系统参数并与实际工程进行了验证,结果非常吻合。     

曲柄偏心式飞剪结构的力学分析

一、引言曲柄偏心式飞剪用于剪切行进中的钢坯。其传动简图如图1。主电机 M 通过减速机 A 的Ⅰ及Ⅲ两轴分别驱动工作机座 B 的齿轮 Z_6及 Z_4。后者又分别通过齿轮 Z_7及 Z_5驱动剪切机构 C 的导架2及偏心轴1。剪切机构相对于作业线上下对称。其运动状态亦上下对称,故分     

曲柄连杆式飞剪剪切不断和趴头的原因分析

利用图解法绘出剪刃的运行轨迹以及各机构元件使用磨损后对运行轨迹的影响,分析了带钢厂曲柄连杆式飞剪轧件剪切过程中轧件剪切不断、趴头的原因,并根据原因制定相应的改进措施,对飞剪进行改进、维护保养,以便减少轧件剪切趴头现象。     

曲柄连杆式飞剪的运动学分析

研究了某棒材轧钢车间的曲柄连杆式飞剪,建立了曲柄连杆式飞剪的运动学数学模型,利用Matlab数学软件分析了剪刃随曲柄旋转的运动轨迹,在剪切范围内的剪刃水平分速度和加速度,为飞剪机的工程研发和工程指导提供了理论依据。     

起停式曲柄飞剪剪切力能参数计算及仿真分析

建立了带飞轮的起停式曲柄飞剪机剪切力能参数的计算模型。剪切轧件所需剪切功由传动系统释放动能提供,可根据电机起动力矩确定电机功率。曲柄转动速度变化规律和飞轮尺寸决定了传动系统释放的动能、电机能否在允许转角和允许时间内起动以及剪刃水平分速是否满足飞剪速度的要求。以马钢VMC40N棒材飞剪机为例进行了仿真。结果表明,用该模型确定起停式曲柄飞剪机剪切力能参数并用于轧件剪切力能检验及同类飞剪的设计是可行的。     

工艺板T400在剪切自动控制中的应用

剪切控制在工业自动控制中应用十分普遍。工艺板T400剪切控制标准软件通过剪切的闭环控制，能够实现飞剪和横剪的特殊工艺要求。着重介绍了工艺板T400剪切控制标准软件的三闭环控制系统以及飞剪的剪切功能实现，     

Microscopic Evaluation of Strain Distribution in Granular Materials during Shear

The evolution of local strains during shear of particles of a granular material is presented in this paper. A cylindrical specimen composed of 6.5-mm spherical plastic particles was loaded under an axisymmetric triaxial loading condition. Computed tomography (CT) was used to acquire three-dimensional images of the specimen at three shearing stages. The high-resolution CT images were used to identify the 3D coordinates of 400 particles. Nine strain components (normal, shear, and rotation), rotation angles, and local dilatancy angles for particle groups were calculated, and their frequency distribution histograms are presented and discussed. It was found that there is no preferred shear direction, and the standard deviation values for shear strain components (εxy, εxz, and εyz) were almost equal for the specific test shearing stage. Shear strains as high as 25.6% were recorded for some particle groups. Furthermore, granular particle groups rotated in the 3D space with almost equal amounts of rotation strains when loaded under axisymmetric triaxial condition. Rotation strain values are very close to the corresponding shear strains. Compared to particle sliding, rotation plays a major role in the shearing resistance of granular materials. The cumulative vertical rotation angles can be as high as 38° and the horizontal rotation angles have values as high as 60°. The statistical distributions of the local dilatancy angle (ψ1) of particle groups were calculated and found to be increasing as shearing continues. The “global” dilatancy angle value is very close to the mean local ψ1 during the first stage of shearing (i.e, when global εz = ?7.3%)     

HK回转式四曲柄飞剪动力学分析

通过对ＨＫ 回转式四曲柄飞剪动力学分析和剪切力的计算,提出了在实际剪切中选取适当的剪切速度来降低主曲轴滚动轴承冲击力的观点。     

Micro and macroscopic aspects of shear band formation in internally nitrided single crystals of Fe-Ti-Mn alloys

The formation of localized shear bands in single crystals of internally nitrided alloys of Fe-Ti-Mn was studied experimentally and theoretically. The experimental studies included observation of the dislocation substructures that are formed at and near shear band/matrix interfaces along with documentation of the crystallography of the localized shearing process. Computational studies of tensile deformation of the crystals using the finite element method, that incorporated a large strain, strain rate dependent constitutive theory for crystalline slip, were carried out and the results were compared to the experimental observations. Mechanical tests, and in situ metallographic observations of shear band formation, showed that localized shearing occurs while the materials are continuously hardening and before “damage”, through microfracture, begins. Electron diffraction and imaging of the deformation substructures near shear band interfaces showed that an important part of the localization mechanism is nonuniform lattice reorientations that cause a “geometrical softening” of the lattice. The numerical studies are in good agreement with the experiments and demonstrate the role of material strain hardening and strain rate sensitivity.     

曲轴滑轨式飞剪动力分析及电机选择

分析了曲轴滑轨式飞剪剪切过程的受力情况,得出了飞剪输入轴的驱动力矩,选出了合适的交流伺服驱动电机。该电机在本钢某飞剪上使用,效果良好。     

Continuum Bed Model for Estuarine Sediments Based on Nonlinear Consolidation Theory

The goal of this note is to examine a continuum theory that describes the evolution of sediment beds when subjected to time-dependent shearing forces resulting from surface water movement. The bed was conceptualized as a medium with continuously varying properties such as shear strength and void ratio. The nonlinear equation describing finite strain consolidation, and the complicated nature of the shearing forces acting on top of the bed, preclude the possibility of analytical solutions. Ramifications of linearizing the governing flow equations were explicitly evaluated for applications in bed modeling. Numerical solutions were obtained for the linear and nonlinear models under transient boundary conditions. Model results indicated that the linear model typically predicts lower void ratios, and consequently underestimates the amounts of sediment eroded from the bed as compared to the nonlinear model.