Research on roll forming process and springback based on five-boundary condition forming angle distribution function

Journal of Mechanical Science and Technology - In the present study, a five-boundary conditional distribution function of the forming angle is proposed. The stress, strain, and springback of a...     

卷板机弯制角钢圈工装夹套

在机械加工、石油化工设备制造,金属结构成形中经常要弯制不同直径的角钢圈,筒要介绍一种利用普通三辊卷板机配之相应夹具即可进行弯制角钢圈技术方法。     

Optimization of bending sequence in roll forming using neural network and genetic algorithm

In the roll forming process, the bending sequence plays a major role in the product quality. The optimal bending sequence results in the smallest number of passes and the flawless process. This paper presents a new optimization procedure of bending sequence in a roll forming process. The multilayer perceptron is used to build the neural network (NN), which models the variation of longitudinal strain in process while the genetic algorithm (GA) is employed to optimize the bending sequence. The data used for training the network is automatically obtained by the integration between CAD and CAE. The values of peak longitudinal strains are maximized while the number of passes is reduced to the smallest and the constraint conditions being set on the maximal longitudinal strain to avoid buckling. The overbending at final pass after spring back is also considered in this paper. Two roll forming processes are optimized in order to prove applicability and efficiency of the optimization procedure. This method maintains the longitudinal strain less than the buckling limit, whereas reducing the number of passes to the smallest. Thus, the advantages of the proposed method show the high applicability in designing and optimizing the bending sequence in the roll forming process.     

板材大圆弧冷弯辊型设计与应用

对客车顶棚的金属板材成型机实行改进 ,进行成型方案的确定、辊型圆弧半径及成型次数等的计算 ,并在实验的基础上设计出辊型 ,经安装调试后达到了设计要求     

五次CVC辊形曲线的分析与设计

CVC辊形曲线可以利用一套轧辊满足不同轧制规程的凸度控制要求,但常用的三次CVC辊形不具备高次凸度控制能力.为更好地控制复合浪形,进一步提出了五次CVC辊形曲线.通过对五次CVC辊形曲线的凸度控制原理与特点的分析,得出了五次CVC辊形的二次凸度与四次凸度随窜辊的变化规律,并提出了基于初始凸度比的曲线设计思路与方法,实验证明,该设计方法合理有效,能够很好地对现有CVC辊形曲线进行分析和改进.     

Energy efficiency of cold roll forming process

Cold roll forming is an important sheet metal forming process for the mass production of a variety of complex profiles out of a wide spectrum of materials and thicknesses. The energy efficiency of such a continuous bending process may lead to a significant reduction in energy consumption. In this paper, the energy efficiency indicator is introduced for the case of roll forming. In order for this indicator to be calculated, analytical models are proposed and developed for the estimation of the energy consumption and the production rate. An application to a U-section profile and the effects of the process parameters on the energy efficiency indicator are discussed. The overall contribution (in percent) of the main process parameters on the energy efficiency indicator is calculated through a matrix of experiments. The results have shown that the most influential process parameters, on the energy efficiency of the cold roll forming process, are the bending angle concept, the line velocity, and the inter-distance among the roll stations.     

Effect of heating paths on strain distribution of plate in laser forming

In laser forming, a desired shape for a metal plate can be obtained by controlling a laser scan path and process parameters. The distance planned between parallel scan paths is larger in current laser path planning in order to avoid interference between them, and thus a continuous strain field cannot be formed. In addition, crossed heating lines are also adopted for forming complicated parts. The effects of the parallel and crossed scanning paths on the deformation field were investigated in this paper. The results show that for parallel heating lines, plastic strain fields produced by adjacent scans do not affect each other when the path spacing is greater than the laser spot diameter, but the plastic strain fields produced by the adjacent scans affect each other when the paths spacing is less than the laser spot diameter. A desirable continuous plastic strain field can be achieved by choosing appropriate path spacing and process parameters. For the crossed heating lines, the plastic strain field is different when adopting vertical and diagonal crossings. The influence between the different heating lines must be considered for high-precision laser forming.     

单轴变截面冷弯成型系统设计

冷弯成型是一种高效、节能、节材的板金属成型工艺。在阐述冷弯成型基本特点的基础上,介绍了一种新型冷弯成型技术—柔性冷弯成型的概念与系统构成。详细介绍了北方某大学研发的单轴变截面冷弯成型机的机械结构,阐述了实现板材变截面成型的基本控制策略,分析了变截面轧辊的控制系统结构与控制原理,简述了控制系统的软件平台。通过轧制实验,分析了变截面板材轨迹控制精度及各种影响因素,为今后进一步开发变截面生产线提供了有益的经验。     

配气凸轮轮廓曲线设计的多目标函数建模

配气凸轮机构是发动机的重要部件,凸轮轮廓曲线的设计至关重要.为获得高的进排气效率,可建立以丰满系数为目标函数的数学模型;另外,基于凸轮机构的工作特点,表面磨损是它的主要失效形式,可依此建立第二目标函数.文中计论了配气凸轮机构中凸轮轮廓曲线的多目标函数数学建模问题.     

简易卷板机设计

针对小型企业生产薄板圆筒件品种规格多、质量要求高、工期紧的难题,研制出一种简易卷板设备,很好地解决了这个难题。     

弯矩作用下肋的分布对肋板的振动影响

加强肋旨在降低薄板结构的振动,研究肋的交叉分布、横分布、纵分布、肋截面参数、板厚因素的变化对振动的影响,通过正交试验,利用有限元法对一两端固支的矩形加肋板进行频率响应有限元分析,计算从1～200 Hz的响应,得到评定薄板振动量的大小。算例表明,在肋的质量不变的情况下,采用横向布置,肋的截面为15 mm×20 mm,板厚为0.014 m时振动量最小。运用正交试验、有限元法、虚拟试验相结合的方法处理具体的数据,避免庞大的实物试验所需要的高成本。     

凹印版辊打样机大鼓的优化设计

通过对打样机大鼓的零件分析,建立数学模型,对目标函数重量进行优化得出了优化结果;通过UG NX软件对大鼓进行建模和有限元分析,得到相应的位移云图、应力云图和优化结果,两者计算结果非常接近,为大鼓的设计提供了重要理论依据.通过应用发现优化后的结果可行.     

Transient bending of a piezoelectric circular plate

Thin, piezoelectric circular plates are frequently used as active components in transducer and smart materials applications. This paper reports on the exact, explicit solution for the transient motion of a piezoelectric circular plate, built-in or simply supported on the edge and electrically grounded over the entire surface. Expressed by elementary Bessel functions and obtained via exact inverse Laplace transforms, the solution enables the efficient calculation of accurate system parameters.     

球壳板一次成形研究

通过建立球片数据模型,总结出一种较为新颖的球壳板展开方法,以建立成型球片与原料钢板之间的对应关系.该方法设计简单,制作方便,且精样板精度高,实用性强.     

Simulation and experimental verification of flexible roll forming of steel sheets

Roll forming is a sheet metal forming process that has been used for decades. Usually roll-formed sections have a constant cross section. Flexible roll forming is a brand new forming process that produces parts with variable cross sections, in which the rollers translate back and forth in a direction that is perpendicular to the sheet feeding direction. Theoretical analysis gives an explanation of the plane strain state, compressive stresses, tensile stresses, and shear stresses in flexible roll forming. In order to analyze the mechanics and the deformation characteristics of flexible roll forming, the finite element method (FEM) model of a 17-step flexible roll forming process is established. The yield criterion used in the FEM simulation is Hill 48, and the parameters of which are solved with the yield stresses under different loading conditions and are firstly verified with a plane strain tensile test. The complicated roller paths are realized with data extracted from the computer-aided design (CAD) files with VC++ programs developed by the authors. We developed the first flexible roll forming prototype machine in China, with which the roll forming experiment of a side door beam is performed. Final shapes of the experimental and numerical results are compared. It is shown that the numerical results based on Hill 48 yield criterion that is solved with yield stresses agree well with the experimental results, which indicates that the simulation model can well reflect the real forming process. Detailed analysis of the distribution and history of plastic strain, longitudinal strain, shear strain, and thickness of both the constant cross section and the variable cross section is performed, which is of great help to understand this forming process.     

Effect of loading pattern on longitudinal bowing in flexible roll forming

The flexible roll forming process can be used to fabricate products with a variable cross-section profile in the longitudinal direction. Transversal nonuniformity of the longitudinal strain is one of the fundamental characteristics of blank deformation in flexible roll forming. Longitudinal bowing is a shape defect caused by transversal nonuniformity of the longitudinal strain. In this study, loading patterns in flexible roll forming are investigated in order to reduce the longitudinal bowing in a roll-formed blank. To analyze the effects of loading patterns on longitudinal bowing, two different forming schedules are implemented. In schedule 1, loading patterns with different bending angle increments are designed under fixed initial and final bending angles. In schedule 2, loading patterns with different initial bending angles under the fixed final bending angle are designed. Our results show that the bowing heights are significantly affected by the loading patterns. The bowing susceptibilities vary with blank shape such as trapezoid, convex, and concave shapes. In addition to the peak longitudinal strain at the respective roll stands, the cumulative longitudinal strain from the initial to final stands is shown to be a reliable index in predicting the tendency of longitudinal bowing.

     

一种薄板异型材的滚弯成型方法

介绍了薄板异型材滚弯成型的五工步成型工艺过程及轧辊设计要点等相关问题,为薄板滚弯成型提供一点经验。