非稳态轧制过程的热力耦合刚塑性有限元模拟

采用三维大变形热力耦合刚塑性有限元法对平板轧制咬入阶段进行仿真,仿真条件与实际轧制过程一致。将仿真结果与实际生产数据进行比较,结果表明采用该方法对非稳态轧制过程进行仿真是可行并且可靠的。研究了非稳态阶段的轧制力分布特点和轧件的变形特点,分析了轧件表面温度对头部厚跃现象的影响规律。     

非稳态轧制过程的热力耦合刚塑性有限元模拟

采用三维大变形热力耦合刚塑性有限元法对平板轧制咬入阶段进行仿真,仿真条件与实际轧制过程一致。将仿真结果与实际生产数据进行比较,结果表明采用该方法对非稳态轧制过程进行仿真是可行并且可靠的。研究了非稳态阶段的轧制力分布特点和轧件的变形特点,分析了轧件表面温度对头部厚跃现象的影响规律。
     

金属轧制过程工作界面非稳态润滑模型研究

基于非稳态流体动力润滑理论和相应的数学物理方法,建立了板带轧制时工作界面非稳态润滑基本模型。通过入口区的分析,确定了入口油膜厚度。考虑了非稳态变量如带张力、轧制速度、入口角等因素对入口油膜厚度的影响,同时还分析了入口油膜厚度的频率响应情形。入口油膜厚度幅值与输入频率成反比。入口油膜厚度呈周期性的变化,但不是正弦波形,所以整个轧机润滑系统是非线性的。非稳态工作区的分析建立在已知的入口油膜厚度基础之上。通过数值计算,定性地分析了后张应力、表面平均速度、入口角等参数对油膜厚度分布的影响。     

轧制界面非稳态润滑过程系统动力学模型的建立及其数值模拟

运用轧机辊缝动力学的基本理论结合非稳态润滑理论，建立了基于非稳态工作界面的动力学模型。该模型考虑了界面上金属塑性流动过程、界面上部分流体润滑与干摩擦并存的混合摩擦学过程以及工作辊的运动等多重耦合作用。塑性流动过程分析中考虑了界面摩擦状态的动态变化，界面摩擦特性分析中考虑了工作辊运动的动态耦合，因此工作界面上的轧制力模型、界面摩擦模型、工作辊运动模型构成了界面的薄膜约束多重耦合模型。对某大型公司2800轧机垂直系统的自激振动进行了仿真，定量地分析了一些主要参数对轧机垂直自激振动临界速度的影响。     

基于数值模拟的线材轧制成形过程研究

通过对线材热连轧过程传热关系进行分析,利用热力耦合弹塑性有限元方法建立了线材与轧辊的三维数值计算模型,结合热轧生产线的实际情况,对高速线材轧制生产线预精轧区六道次轧制过程中的温度场、轧制力与轧制力矩进行了模拟计算。分析了变形区内温度场的分布和变化规律,探讨了轧制过程中所涉及的几何、材料和边界条件等多重强非线性问题,计算结果为生产工艺制度的改进、工艺参数的优化以及微观组织变化规律的研究提供了理论依据,对现场生产也有重要的参考价值。     

侧压过程板坯温度变化的研究与分析

利用热力耦合有限元的理论,建立了板坯侧压过程的三维热力耦合有限元仿真模型.得到了板坯在稳态变形区内节点温度和轧制力随时间的变化规律,通过轧制力的模拟结果和试验数据比较可知,两者吻合良好.分析结果为板坯侧压规程的制定和轧制力的在线预报提供了理论依据.     

切削工艺参数对切屑形状的影响及其有限元分析

以刚塑性有限元理论为基础,采用有限元仿真技术,对金属正交切削过程中切屑成形进行了模拟仿真,得到了不同的刀具前角和摩擦条件对切屑形状的影响规律。对二维切削过程进行加工实验,结果表明切削模拟结果与实际加工情况比较吻合,可以为实际加工提供参数选择的依据。     

异型扁坯轧制过程的理论与试验研究

利用刚塑性有限元法分析了异型扁坯的轧制成形过程,首次阐明了横向倾斜接触表面上节点速度分量之间的约束关系,得出异型扁坯宽展、筋高充满度及轧制变形和力能参数的变化规律,其结果与实测值相吻合,并求得变形区内部的变形场和金属质点流场。     

60Si2Mn半固态轧制有限元模拟

采用多孔材料的几何模型,利用MARC软件对弹簧钢60Si2Mn半固态轧制进行了有限元模拟,分析了在热力耦合条件下,将半固态材料视为可压缩的刚-粘塑性体时的应力场、速度场、温度场的状况,并研究了不同变形条件下,应力场、速度场的变化规律,由此所进行的模拟工作较好地反映了半固态轧制过程中金属的变形规律。     

基于一种广义摩擦公式的金属非稳态成型过程弹塑性行为的分析

通过理论分析推导，归纳总结了一个广义摩擦公式。同时应用该公式，对典型金属成型过程非稳态轧制过程进行了三维大变形弹塑性有限元分析。对轧辊与工件之间的接触(摩擦)问题，用这种新的摩擦公式进行了较精确计算。对数值计算结果(包括轧制力、轧制力矩以及界面间的正应力和剪应力)进行了分析讨论。证明广义摩擦公式是切实可行的。     

磁流变抛光工艺参数的研究

磁流变抛光是一种新型的光学零件加工方法,它不仅可以精确控制抛光后光学零件的面型,还能得到较高的表面质量和较高的加工效率。本文在介绍磁流变抛光基本原理的基础上,重点分析了磁流变液与工件相对速度对磁流变抛光最终效果的影响规律,在一定速度大小范围内,随着相对速度的提高,抛光加工的效率也会随之提高,光学零件的表面粗糙度会随之降低,并且还提出在抛光过程中保持相对速度一致的必要性和保持相对速度一致的方法,通过实验验证了该方法的正确性。     

不锈钢棒表面滚压加工工艺参数设计与研究

提出一种新的不锈钢棒表面滚压加工方式,使得滚压后钢棒的表面硬度和疲劳强度等机械性能得到提高,解决了传统加工方式中钢棒加工长度受机床床身限制这一难题.并对不锈钢棒表面滚压加工工艺参数进行了设计与研究,着重分析了各工艺参数对不锈钢表面质量及机械性能的影响.     

长轴表面滚压加工过程数值模拟的研究

采用滚压加工的方法对长轴表面进行光整加工,设计了滚轮结构,滚轮采用成对的布局方式,使被加工长轴的受力更加均匀;加工时产生的热量大幅度减少。此外,滚压加工还能够提高长轴光整加工的效率。利用显式动力学有限元分析软件ANSYS/LS-DYNA,模拟分析了3种形状的滚轮对长轴被加工表面产生的塑性变形,长轴和滚轮之间的接触力,加工之后长轴表面节点的实际位移量,以此为长轴的滚压加工选取合适的滚轮形状提供理论依据。     

Effect of processing parameters on the relative density of spray rolling 7050 aluminum alloy strip

Coordinate measuring machines (CMMs) play an important role in industry to verify dimensions and tolerances of manufactured parts. The accuracy of measurements using CMMs depends on the capability of the mathematical models to represent the geometry of the part and on the fitting algorithms to find the best solution that will correct the axes orientation and origin offsets between the measurements and of the nominal form. This study describes two approaches: a dynamic angle approach that was developed to improve the performance of the Limacon approximation; and a free-form orientation approach that models the assessed form and cancels out the axes misalignments by using the flatness model. The accuracy of these models was tested using data that was available from previous studies. Results from this analysis showed that the two developed approaches improve the calculation of the zone of error of circular, spherical, cylindrical, and toroidal features; and the estimation of the parameters, origin offsets, and axis misalignments. Therefore, it can be concluded that the developed approaches performed quite efficiently for adoption in product metrology.     

不锈钢超细长轴表面滚压加工工艺参数研究

介绍了不锈钢超细长轴表面滚压加工工艺参数的选取,使得超细长轴的加工长度不在受到其缺点的限制,经过加工后可使表面硬度和疲劳强度等机械性能得到提高。并对加工出的超细长轴表面粗糙度进行详细的分析。     

基于等角度重采样的非稳态振动数据分析方法研究

在俯冲拉起、地面开车发动机不同状态之间切换等某些特殊状态下,直升机动部件的旋转频率是个变化量,采用傅立叶变换或者傅立叶级数展开算法进行频谱计算,得到的是对应数据的均值,由于频率在时刻变化,所得结果并不能真实反应这一过程中的振动量值。为解决这一问题,本文以旋翼转速为基准,引入等角度重采样方法对振动数据进行阶比分析,得到了不同阶次频率的真实振动量值,为特殊状态下的振动数据分析提供一种分析手段。     

Non-linear dynamics of inlet film thickness during unsteady rolling process

The inlet film thickness directly affects film and stress distribution of rolling interfaces. Unsteady factors, such as unsteady back tension, may disturb the inlet film thickness. However, the current models of unsteady inlet film thickness lack unsteady disturbance factors and do not take surface topography into consideration. In this paper, based on the hydrodynamic analysis of inlet zone an unsteady rolling film model which concerns the direction of surface topography is built up. Considering the small fluctuation of inlet angle, absolute reduction, reduction ratio, inlet strip thickness and roll radius as the input variables and the fluctuation of inlet film thickness as the output variable, the non-linear relationship between the input and output is discussed. The discussion results show that there is 180° phase difference between the inlet film thickness and the input variables, such as the fluctuant absolute reduction, the fluctuant reduction ratio and non-uniform inlet strip thickness, but there is no phase difference between unsteady roll radius and the output. The inlet angle, the steady roll radius and the direction of surface topography have significant influence on the fluctuant amplitude of unsteady inlet film thickness. This study proposes an analysis method for unsteady inlet film thickness which takes surface topography and new disturbance factors into consideration.     

Effects of rolling parameters on work-roll temperature distribution in the hot rolling of steels

Temperature variations of work-rolls in the process of hot rolling of slabs were analyzed by solving heat conduction equation with time-dependent boundary conditions. The Raylieght-Ritz and the finite-element methods were employed to solve the governing equation. To improve the accuracy, the thermal relationship between rolling metal and work-rolls was taken into account as well as the effects of different parameters such as interface heat transfer coefficient, rolling speed, and slab initial temperature were considered in the calculations. To verify the employed model, a comparison was made between the predicted and the recorded time-temperature history and good agreement was observed. Modelling results show that the interface heat transfer coefficient and rolling speed are important factors that vary effectively the temperature field within the work-roll. In addition, the interface heat transfer coefficient is affected by the other parameters and factors such as flow stress behavior of the metal being rolled and initial temperature of metal. Therefore, in order to determine an accurate temperature field within the work-rolls, flow behavior and temperature distribution in the rolling metal should also be calculated at the same time.     

基于小波神经网络的轧机接轴扭振状态识别研究

构造了一种新的适合于轧机扭振状态辨识的混合递阶遗传算法优化小波神经网络模型,实际轧钢现场测试数据输入构造的混合递阶遗传小波神经网络扭振状态识别模型,对网络模型进行训练,从而实现现代高速轧制条件下轧机主传动系统不同工况条件下的扭振状态的学习和自适应判断,结果验证了该辨识模型的可靠性.     

Research on interactive influences of parameters on T-shaped cold ring rolling by 3d-FE numerical simulation

Cold ring rolling is a much complex physical process with multi-factors. Two forming parameters, the feed rate of mandrel and the rotational speed of main roll, affect the quality of deformed ring significantly and the feed amount per revolution of ring in the form of their ratio. By their ratio, the interactive effects of the two forming parameters on the T-shaped cold ring rolling process are explored through 3D-FEM in Abaqus software. The results show: firstly the study objects (roll force, growth rate of diameter, degree of inhomogeneous deformation, filling capability of groove, average side spread and fishtail coefficient) are almost invariable if the two parameters are increased (or decreased) proportionally; secondly whether the ratio is changed by the feed rate of mandrel or by the rotational speed of main roll, the variation of each study object with the ratio is approximately the same; thirdly the increase of the ratio is beneficial to the growth of diameter and the restrictions of inhomogeneous deformation, average side spread and fishtail coefficient, but it causes the roll force to increase and the filling capability of groove to decrease.