Sensitivity analysis of parameters for multi-stand roll forming using a new booting model

Multi-stand roll forming is a process that has very complicated deformation behaviour and shows significant nonlinearity.In this paper, the sensitivity analysis of parameters for multi-stand roll forming was performed via a new booting finite element method(FEM) model.Compared with the most of simulation, the new model is more consistent with production process and can account for the effects of roll rotating speed.Based on the model, the process of an open section channel formed with 10 passes was simulated and the sensitivity analysis was conducted with orthogonal experiment design combined FEM model.The multi-stand roll forming process can be efficiently analyzed by the new booting model.And sensitivity analysis shows the hardening exponent plays an important role in controlling the quality of the products.     

Computer simulation of the continuous annealing recrystallization for cold-rolled strip in galvanizing line

The continuous heating transformation program is developed to investigate the influence of continuous annealing technological parameters on recrystalization for cold-rolled strip in galvanizing line. This program can be used for the calculation of the continuous annealing temperature field of strip steel, determination of the start and end time of recrystallization in continuous heating process, and procurement of the continuous heating transformation diagram. The temperature field for continuous annealing is simulated by means of finite difference method. Based on the Scheil superposition principle, the continuous heating transformation curve is obtained by using time temperature transformation (TTT) curve which is measured experimentally. The developed program has been used in practice, and the strip speed on production line increases by more than 10%.     

货车冲压件CAPP系统的研究

针对货车板材冲压件,就开发其CAPP系统进行了研究。以成组技术的基本原理为依据,提出了零件描述和工艺过程生成的新方法,其主要特点是:计算机辅助编码,运用专家知识库进行决策判断,检索与创成相结合。系统采用模块化的设计方法,做到了系统的柔性化。系统采用了汉字DBASE数据库和MS-PASCAL语言,适用于IBM-PC机及其兼容机。     

Study on bending conditions of plate in coil box

In a coil box between the roughing and finishing stands on a hot strip mill, a problem has been encountered that the entry region of the plate touches the bending rolls and deforms. As a result, the defective coil occurs. The condition of plate bending, which forms a new deformation feature in coiling, is analyzed. In this paper, the authors focus on the research of the effects of coiling parameters, such as the thickness of plate, roll speed and feeding speed of plate in coil box, and on specific plate bending. A finite element method is developed to simulate this coiling process. Based on numerical simulation, the effects of the coiling parameters on the mechanics and deformation of the bending plate are obtained. Numerical simulation tests have verified the validity of the developed model.     

Analysis of the cross-wedge rolling process of toothed shafts made from 2618 aluminium alloy

The paper presents the results of a thermo-mechanical analysis of the rolling two stepped shafts. One of the shafts has a toothed step with skew teeth, while the other has a worm winding in the shape of a trapezoidal screw. The shape of the rolling tools resembles that of the tools used in the Roto-Flo rolling method; yet unlike in Roto-Flo, the shafts are hot-rolled and no centres are used to stabilize the position of the workpiece during the forming process. For the calculations made with use of the DEFORM-3D process simulation system it has been assumed that the rolled shafts are made from 2618 aluminium alloy. As a result of the calculations made, it has been found that the toothed stepped shafts can be formed in one pass by means of the cross rolling process. Additionally, the temperature and strain distribution in the rolled product have been determined as well as some data concerning the forces which are necessary for the rolling process have been obtained.     

Numerical study of the forming process of high frequency welded pipe

The roll forming process is applied to the manufacturing of high frequency welded (HFW) pipes,section steels,etc. In this paper,the roll forming process of the HFW pipe is simulated with the finite element method (FEM). A user-defined material routine of the commercial finite element code ABAQUS/Explicit is developed,and the mixed hardening constitution model is realized through the user-defined material routine. Based on the mixed hardening constitutive equation,the numerical simulation of roll forming pro...     

A NEW SYSTEM DYNAMIC EXTREMUM SELF-SEARCHING METHOD BASED ON CORRELATION ANALYSIS

Inindustrialprocessesself searchingoptimumcontrolsystemshavebeenwidelyused ,becausetheydonotneedamathematicalmodel,whichhaveblockdiagram (seeFig .1) .Theprincipleistomakethecontrolsystemreachitsoptimumoperatingstatebycontinuousmeasuringandcontrolling.Thenec essaryconditionisthattheplantsmusthaveanex tremumcharacteristic[1 ] .Thekeyofself searchingoptimumcontrolishowtofindthesystemextremum pointautomati cally .Therearemainlytwokindsofself searchingmethods,whicharethecontinuoussearchingandthest…     

新型钢门窗型材冷弯成型CAPP中的工艺生成方法

根据薄壁空腹钢门窗型材及其冷弯成型工艺的特点，在新型薄壁空腹钢门窗型材冷弯成型ＣＡＰＰ／型辊ＣＡＤ一体化系统中综合应用检索、变异、创成方法来生成型材的冷弯成型工艺，使系统实用、使用方便、运行快捷且具有一定的智能性，对应用ＥＳ思想和方法生成成型工艺的方法进行了较详细地介绍。     

牵引式滑坡后缘破裂面计算方法

斜坡发生牵引式滑动破坏,形成后缘拉裂面,后缘面形态对滑坡稳定性分析及推力计算具有重要影响,但其在滑坡体内部的空间特征难以确定. 为探索后缘破裂面的形成机理和计算理论,建立合理的数学力学模型,提出后缘破裂面倾角的计算方法,确定各级滑块的最危险破裂倾角,并将其所在破裂面作为条分型式,计算各级滑块的稳定系数,实现滑坡渐进破坏过程的稳定性分析;同时,开展室内模型试验进行验证,研发了新的模型试验装置,其主体由若干渗透盒组成,能够构成各种几何形状的分段式滑面;通过向不同分段的渗透盒注水,实现牵引式滑坡的逐级失稳过程,并测试各级滑块最终形态的后缘破裂面倾角. 结果表明:后缘破裂面倾角计算值与试验值具有较高的一致性,主要集中在70° 左右,相对误差介于2%～4%之间;滑坡体失稳形成的各级滑块稳定性不同,第一级滑块的稳定程度最差,越向坡体后侧稳定性越好. 可为牵引式滑坡的稳定性分析提供新的思路.      

基于约束描述的公路路线设计过程模型

公路设计问题是"定义不清晰问题",其设计过程是从设计要求和约束条件出发,逐步满足约束的过程.针对目前公路CAD系统仅从绘图和计算层面对设计师支持的现状,笔者在文中讨论了公路设计过程的典型思维方法,提出建立设计过程模型以提高公路CAD系统的支持水平,定义了基于约束描述的公路路线设计过程模型,给出了形式化描述,并以公路平面设计为例说明了模型的应用.     

Research on confirmation of basic technological parameters of tension levellers based on neural network and genetic algorithm

Confirmation of basic technological parameters of tension levellers is the most important factor of leveling strip. Up to now, most factories have used experts' experience to decide these parameters, without any established rule to follow. For better quality of strip, a valid method is needed to decide technological parameters precisely and reasonably. In this paper, a method is used based on neural network and genetic algorithm. Neural network has a good ability to extract rules from work process of tension levellers. Then using neural network, which has learned from a lot of working samples, to be the evaluation of fitness, genetic algorithm could easily find the best or better technological parameters. At the end of this paper, examinations are given to show the effect of this method.     

Simulation of tube forming process in mannesmann mill

The finite element method (FEM) is used for simulation of the tube piercing process in Mannesmann mill. The numerical model is described with taking into consideration thermal phenomena in metal during forming. The simulated results visualize dynamic distributions of mean stresses, temperature, velocity and shear stresses, especially inside the workpiece. On the basis of the basic parameters, the phenomenon in the piercing process is analyzed. The model is verified by comparing the values of calculated force parameters of the piercing process and those measured in laboratory conditions.     

A new approach of intelligent design and optimization for shell nosing

Preform design for shell nosing product without machining the inner surface after forming is an experience-extensive work. Generally, the initial design needs to be modified and simulated consequently to get proper preform and nosing die, and the iterative process is time consuming. This paper puts forward a new approach, in which the suitable initial design can be obtained by knowledge-based intelligent technology and the optimal design can be acquired by finite element method (FEM) based geometrical modification. With the CAX object model as the bridge of CAD and CAE, the CAD model with simulation knowledge can be transferred into CAE automatically, and the CAE result can be automatically utilized as well. Based on the comparison between the simulated shape and the desired shape, the dissatisfactory area will be modified. A new simulation and modification process will be carried out based on the modified design. The process is repeated iteratively to get the optimal design. This approach utilizes the commercial CAD and CAE software, without the need of complex back-forward FEM procedures. Based on the new approach, an in-home intelligent shell nosing design and optimization system is developed, and a case study proves that this system can reach a reasonable design efficiently.     

基于有序聚类分析的高速公路路段长度划分研究

提出了基于F isher有序聚类分析的高速公路路段长度划分方法,以事故数沿每公里的空间分布为聚类指标进行路段长度划分,通过实例验证,一方面发现按照F isher有序聚类分析方法划分路段的结果能够使得分段后的事故频数很好地服从一定的概率分布,有益于模型的构建;另一方面,应用该方法分段能够很好地考虑事故的发生水平,把事故水平相近的邻近路段划分到同一研究样本内,有助于准确地量化影响因素的作用,在样本量不是特别大的情况下,能够突出两者之间的关系.     

船体外板冷弯成形回弹数值模拟关键技术研究

如何精确的预测出回弹量在船体外板冷弯成形中是一个非常关键的因素,有限元数值模拟技术的引入,为推动回弹问题的解决提供了有利的工具.文章基于船体外板多点成形技术冷压成形的回弹数值模拟的数学模型的建立问题,重点介绍了本构模型、单元类型、数值计算方法的选择及接触与摩擦的处理等,为后续的回弹模拟研究奠定了基础.     

BP神经网络在健康监测基准模型损伤识别中的应用

本文针对ASCE提出的健康监测基准问题的结构模型,分析了基于固有频率的结构损伤识别方法,使用MATLAB软件模拟不同的结构损伤情况,根据得到的固有频率构造BP神经网络输入参数并进行相应的训练,通过神经网络对结构损伤分步分层次的进行诊断。通过数值分析结果说明这种方法可以取得较好结果,也进一步说明神经网络技术是进行结构损伤识别有效方法。     

高速公路隧道洞口段仰坡沉降变形监测分析与预测

通过对非等步长序列数据的处理,运用传统等步长GM（1,1）模型的建模原理,建立非等步长序列的GM（1,1）模型,对高速公路隧道洞口段仰坡沉降变形进行预测和模拟。结果表明,该模型预测精度高,预测结果可靠。与传统模型相比,该方法更适用于实际监测,更具有实用价值,进一步推广了灰色系统理论在工程中的应用。     

Forming path optimization for press bending of aluminum alloy aircraft integral panel

Because of the light weight, high stiffness and high structural efficiency, aluminium alloy integral panels are widely used on modern aircrafts. Press bend forming has many advantages, and it becomes a significant technique in aircraft manufacturing field. In order to design the press bend forming path for aircraft integral panels, we propose a novel optimization method which integrates the finite element method (FEM) equivalent model based on our previous study, the artificial neural network response surface, and the genetic algorithm. First, a multi-step press bend forming FEM equivalent model is established, with which the FEM experiments designed with Taguchi method are performed. Then, the back-propagation (BP) neural network response surface is developed with the sample data from the FEM experiments. Further more, genetic algorithm (GA) is applied with the neural network response surface as the objective function. Finally, experimental and simulation verifications are carried out on a single stiffener specimen. The forming error of the panel formed with the optimal path is only 5.37% and the calculating efficiency has been improved by 90.64%. Therefore, this novel optimization method is quite efficient and indispensable for the press bend forming path designing.     

一种大型带状数字地形模型建模方法

根据铁路选线系统海量地形数据的特点，以快速、自动为目标，通过在构网建模过程中对空白区域和分块边界的处理，综合利用图形子区边界提取、异侧找点、最短距离等原则，提出了一种基于约束Delaunay三角网建立大型带状三角网的快速建模方法．通过对建立的大型三角网模型进行四叉树分割和分块存储，有效提高了建模成果的利用效率．该方法已成功地用于“虚拟环境选线系统”的开发，通过几段实际线路的应用，证明了用此方法建立连续带状数字地形模型的有效性和可靠性．     

Engineering design optimization based on intelligent response surface methodology

An intelligent response surface methodology （IRSM） was proposed to achieve the most competitive metal forming products, in which artificial intelligence technologies are introduced into the optimization process. It is used as simple and inexpensive replacement for computationally expensive simulation model. In IRSM, the optimal design space can be reduced greatly without any prior information about function distribution. Also, by identifying the approximation error region, new design points can be supplemented correspondingly to improve the response surface model effectively. The procedure is iterated until the accuracy reaches the desired threshold value. Thus, the global optimization can be performed based on this substitute model. Finally, we present an optimization design example about roll forming of a ＂U＂ channel product.