BP-NSGA和FEM相结合优化万能型钢轧机机架圆角

万能型钢轧机机架圆角直接影响机架的应力分布、纵向和横向变形,从而影响机架的强度、刚度、寿命、H型钢的精度和尺寸。根据万能型钢轧机机架的受力特点和几何对称性,建立机架的有限元模型。利用有限元软件ANSYS分析机架圆角对其应力分布及位移的影响。把改进的带精进策略的非支配分类遗传算法(NSGA)和有限元相结合,建立新的优化方法。并用BP神经网络建立非支配分类遗传算法(NSGA)的适应度函数。以机架的纵向位移和体积为目标函数,利用这种新的优化方法和ANSYS自带的零阶和一阶优化方法优化万能型钢轧机机架圆角,与ANSYS自带的零阶和一阶优化方法相比,这种新的优化方法取得了良好的优化效果。     

基于ANSYS软件的万能型钢轧机机架圆角的多目标优化设计

利用ANSYS软件参数化建立万能型钢轧机机架几何模型,再以刚度和质量为目标函数,对机架圆角进行多目标优化设计,使机架在满足强度条件的前提下,在质量较小的时候得到较大的刚度。这种分析方法和求得的结果对万能型钢轧机的设计有非常重要的参考价值。     

模糊数学方法在万能型钢轧机机架圆角的多目标优化中的应用

目前,多目标优化设计中的加权系数基本上都是通过经验来给定,文章在利用ANSYS软件对万能型钢轧机机架圆角进行多目标优化过程中,应用模糊数学中的隶属函数,计算出不同加权系数组合的最优解和理想解的贴近度,从而确定出一组合理的加权系数,为加权系数的确定提供了理论依据。     

轧钢机机架圆角的形状优化设计

本文利用具有局部区域快速重设计功能的有限元形状优化设计程序OPTSDP对轧钢机机架过度圆角进行了形状最优设计。计算表明:象轧钢机机架这类大型结构的局部最优设计,采用OPTSDP程序具有较高的效率和得到比较满意的结果。     

万能型钢轧机调零方案的改进

介绍了马钢万能型钢轧机调零所存在的问题 ,以及轧机调零顺控方案的改进和应用情况。     

中厚板四辊轧机机架优化设计的遗传算法

基于中厚板四辊轧机机架的优化问题的性质，提出了用遗传算法来进行优化设计，并在计算机上进行求解，通过与用惩罚函数法所获得的最优解的比较，表明该算法在本优化设计中的有效性。     

4200mm轧机机架的三维有限元分析

应用ＳＡＰ５程序，对４２００ｍｍ轧机机架进行了有限元分析，找出了危险点的位置，确定了极限安全系数。     

重型轧机联轴器圆角应力集中引流拓扑优化

圆角应力集中是重型装备频繁开裂的一个重要原因。基于应力引流思想,以轧机联轴器为对象,通过拓扑优化技术解决其圆角应力集中问题。建立了联轴器的三维有限元模型,并对其进行了应力分析,表明应力最大部位集中在槽口根部的3个圆角交汇处。对此,根据应力引流思想,将滑块安装槽圆角及内圆柱面定义为优化设计区域,其他部分为非设计区域,以柔度最小作为优化目标,以圆角应力点的最大应力作为约束条件,对叉头圆角进行拓扑优化,得到一个近似槽状的拓扑结构。根据拓扑优化的结果对圆角进行了重新设计以及对比分析。结果表明:优化后圆角交汇处最大应力减少了约100 MPa,降幅达20%,说明应力引流对于改善圆角应力集中效果明显。     

基于有限元的轧机机架的机械性能分析

在对板簧轧机机架的结构形式进行深入分析的基础上,建立了轧机机架的三维模型.以ANSYS11.1有限元软件作为分析工具,对两种不同形式的轧机机架进行三维模型的有限元模拟,计算了机架的应力和位移,得到了机架的应力图与位移图,得出机架各单元和各节点的位移量及应力值.分析结果表明,有中间横梁机架的Y向位移明显小于无中间横梁的机架结构,且设备刚度提高了18.77%,为轧机机架的设计、改造、以及提高轧制精度提了供理论依据和参考数据.     

轧机机架结构分析与几何优化的研究

通过构造机架二维和三维有限元模型，分析比较两种模型应力、应变的差异，从而检验了通常采用的平面应力模型在工程上的适用性。同时采用以几何实体造型和网格自动生成技术为基础的参数化结构几何优化，该方法较以往的方法更具工程意义。     

铜管游动芯头拉拔模具角度优化的有限元模拟

采用二维轴对称弹塑性有限元法对比分析了不同外模模角和游动芯头锥角的配合对拉拔铜管的影响。模拟结果表明,最优外模模角和芯头锥角配合与拉拔应力、摩擦力和芯头稳定位置等因素有关,外模模角、芯头锥角以及两者之间的角度差过大或过小都对铜管的质量不利,这对于精密铜管游动芯头拉拔模具角度的选择,有着一定的参考价值。     

铜管游动芯头拉拔道次优化的弹塑性有限元模拟

借助大型非线性有限元软件Marc，应用二维轴对称弹塑性有限元法模拟铜管多道次拉拔过程，对比分析铜管游动芯头5道次拉拔和4道次拉拔对铜管力学性能和质量的影响。模拟结果表明，为了得到同样规格的铜管，优化拉拔道次可改善铜管拉拔中的不均匀变形、降低成品铜管中的残余应力，同时提高铜管质量，从而提高生产效率，增加生产效益，这对于铜管游动芯头多道次拉拔配模的选择有着一定的参考价值。     

中型轧机生产20/12.5号角钢的孔型设计

介绍了在唐钢中型轧机上开发20／12．5号大规格不等边角钢蝶式孔、成品孔的孔型设计情况。生产实践表明，该产品开发获得成功，产品质量达到标准要求，成材率达90．62％，合格率为99．57％。     

钢轨轧制过程典型导卫系统的有限元模拟

利用有限元模拟方法,对钢轨轧制生产过程中典型导卫系统进行模拟研究,借助大型有限元模拟软件MSC.Marc,分别讨论了入口导板和出口卫板对轧制过程以及轧件变形过程的影响。模拟结果表明,入口导板对轧件顺利咬入孔型以及轧件在该道次的变形过程产生显著影响,出口卫板对轧制过程的顺利进行产生显著影响。通过对模拟结果的分析认为,有限元模拟方法有助于实际生产过程中导卫系统的设计与优化;有限元模拟技术的应用,可提高导卫系统的可靠性,并对轧制过程提供有效而便捷的途径。     

Effect of the shield gas,working angles and displacement angles on the characteristics of fillet joints obtained via GMAW using a high-strength microalloyed steel

ABSTRACT

Fillet joints are one of the most commonly used joints in various industries, in particular for agricultural machinery. However, the complexity of the pieces that require welding often makes accessibility difficult for the welder for this kind of joint, and working and displacement angles are important aspects to be evaluated. In addition, in the GMAW process, the use of the Ar-20%CO₂ mixture as the shield gas has increased at the expense of 100% CO₂, generally requiring an adjustment of the electrical parameters. On the other hand, the incorporation of new materials with higher strength also involves optimizing the welding procedure. The aim of this study was to evaluate the effect of two shield gases (Ar-20% CO₂ and 100% CO₂), three working angles (30, 45 and 60°) and two displacement angles (45° using the push technique and 60° using the pull technique) on the dimensional characteristics of the seam and the mechanical strength of the fillet joint from a microalloyed steel with high strength welded using GMAW. The highest levels of penetration corresponded to the test specimens welded using the pull technique and with CO₂. The over thickness was smaller for conditions with the push technique and the gas mixture. The microhardness of the weld metal, for a similar working angle, was higher for the gas mixture in all cases. Indices of acceptability were developed, which graded geometric aspects and these were compared with the mechanical properties obtained on the welds, showing a good correlation.     

9#锅炉捞渣机十字轴式万向联轴器万向节安装角度的技术改进

中国铝业河南分公司热力厂9#锅炉LLZ型螺旋式捞渣机在公司生产中起着重要作用，如何延长使用周期．降低十字轴式万向联轴器的检修费用，节约能耗，降低成本，最大限度的减少万向联轴节连接销轴的断裂．经过一定时期的观察分析，并结合生产实际情况，探讨了一种很成功的技术改进方式。     

Deformation characteristic of the precision forging of a blade with a damper platform using 3D FEM analysis

A blade with a damper platform is one of the most important types of blades being developed in aeronautical engines. However, this type of blade is complicated in shape, consisting of four feature parts with different geometrical shapes. Besides obvious flow of material along the transverse direction, there is material flow along the longitudinal body during its forging process. In addition, the material used is difficult to deform. All these have a significant influence on the precision forging process of the blade. Thus, it is necessary to choose some feature sections along the transverse and longitudinal direction of blade and systematically understand the deformation characteristics of blade forging process. In this paper, by means of 3D rigid–viscoplastic FEM simulation of the precision forging process of the blade, the deformed meshes, distributions of some field variables, including velocity, effective strain, effective strain rate and effective stress are presented for the four chosen feature cross-sections and the velocity fields are obtained for a selected typical longitudinal feature section, and further the deformation characteristics of forging this blade have been revealed. This research may serve as a guide to the optimization design of the relevant processes and dies.     

Analytical predictions and experimental validation of cutting force ratio, chip thickness, and chip back-flow angle in restricted contact machining using the universal slip-line model

This paper presents analytical predictions and experimental validation of a recently developed universal slip-line model for machining with restricted contact cut-away tools. Three important machining parameters, i.e. the cutting force ratio, chip thickness, and chip back-flow angle, are predicted on the basis of: (1) the universal slip-line model; (2) a maximum value principle for determining the state of stresses in the plastic region in restricted contact machining; (3) Dewhurst and Collins’ matrix technique for numerically solving slip-line problems; and (4) Powell’s algorithm for non-linear optimizations. All predictions are based on purely theoretical calculations with no experimental/empirical data as input. The extensive comparisons between theory and experiments show a reasonable agreement. Major new research findings from this study include: (1) the applicable ranges of an extreme friction slip-line model and of Johnson’s and Usui and Hoshi’s slip-line models; and (2) the general rule of the variation of tool–chip friction conditions. Tool–chip contact in machining with restricted contact cut-away tools is categorized into three broad cases. A theoretical method is also presented in the paper to distinguish different tool–chip contact cases in practical machining situations.