Investigation into forming sequences for the incremental forming of doubly curved plates using the line array roll set (LARS) process

The line array roll set (LARS) process [7] proposed by the authors is an effective metal forming process used to manufacture doubly curved metal plates. To obtain a final shape with the desired bend radii and to minimize any possible defects, the process for forming the desired shape should be systematically and accurately designed. The major purpose of the present work is to analyze the effect of the forming sequences in the LARS process. The experiments are conducted using three types of forming sequences, and the final bend radii and the quality of the formed plates produced by the LARS process are evaluated. It is found that it is more effective to form a doubly curved plate through a singly curved shape in order to improve the quality of the formed plate. A series of forming experiments with various bending radii are conducted and the interaction phenomena in double curvature bending are observed.     

基于楔横轧原理的钢球轧制工艺计算机仿真研究

钢球在工业中的应用非常广泛,特别是矿山用的球磨机对钢球的应用量更是巨大,由于其形状的特殊性,其大批量生产工艺也越来越得到重视.本文应用有限元方法,并基于楔横轧原理对钢球的轧制成形工艺过程进行模拟仿真,通过DEFORM-3D的模拟过程研究了楔横轧各工艺参数对钢球成形过程的影响,根据模拟过程中金属的流动规律对模具进行改良,获得满意效果.     

Analytical model for prediction of deformed shape in three-roll rolling process

In process design of bar rolling, accurate prediction of deformed shape of the rolled workpiece is important in determining the total number of passes. Thus, development of an approximate analytical model for predicting an accurate rolled shape with less computation time will be beneficial for practical purpose. In the present study, such a model for the three-roll system with multi-passes was developed by deriving spread and geometrical configuration formulae from the finite element (FE) analysis results of a seven-passes sequence rolling. In FE simulations, process parameters such as the initial workpiece geometry and the amount of roll draft and roll speed were varied. By comparing spread ratios of FE simulation results three representative geometry changes (round–curved hexagonal, curved hexagonal–hexagonal, and hexagonal–hexagonal) were identified. For each representative geometry change those two formulae were determined in the present investigation. The formulae determined were further applied to a three-roll process with four-passes sequence. The final workpiece geometry predicted based on the model developed was found to be in good agreement with experimental and FE simulation results. Thus, the analytical model developed in the current approach can be effectively used in the design of multi-pass three-roll rolling processes.     

LS-DYNA无网格伽辽金方法在轧制过程三维仿真分析中的应用

文章介绍了无网格方法的进展情况,详细论述了LS-DYNA中的EFG方法;成功地将三维EFG方法应用于轧制过程的仿真分析;完成了三维简单轧制及H型钢万能轧制过程的EFG仿真分析,并与传统的FEM方法进行了对比。证明了EFG方法在三维轧制仿真中的可行性,阐述了EFG方法在大变形仿真分析中的优势。     

环件轧制过程的显式有限元模拟分析

用于金属成形模拟的有限元方程的求解方法 ,主要有隐式和显式积分两种方法。对于复杂的三维变形分析 ,如环件轧制 ,隐式方法需要很长的运行时间。而利用显式方法 ,可以达到很好的效果。本文利用Abaqus /Ex plicit通用有限元程序对径向环轧进行了模拟。     

火车车轮卧式轧制热力耦合有限元模拟分析

车轮轧制是采用压轧工艺生产整体车轮的一个重要工步。目前,车轮成形工艺的研究主要集中在预成形及辐板弯曲等工步,对于轧制工艺研究相对较少。该文结合车轮卧式轧制原理及特点,在有限元分析软件ABAQUS中建立了车轮七辊卧式轧制的三维热力耦合有限元分析模型。根据有限元模拟结果,探讨了车轮轧制过程中,轮坯表面金属流动规律,轮坯应力、应变及温度的分布和变化规律,以及轧制力能参数的大小及变化。研究结果为车轮卧式轧制的有限元模拟分析和生产实践提供了一定的参考。     

环件轧制过程三维动态数值模拟

由于环件轧制受到静力学、运动学和动力学因素的影响,使得控制环件成形具有高度的复杂性,采用传统的试凑法很难满足产品研发的需要。本文基于通用动力显式有限元软Ansys/LS dyna建立了RAW200/160-5型径轴向轧环机的三维仿真模型,对某矩形截面环件进行了虚拟轧制,结果显示了环件扩展和缺陷生成的动态过程以及应力、应变和位移云图。仿真结果表明,采用计算机模拟环件轧制生产过程,对于优化毛坯形状,制定或修改环件轧制工艺,缩减产品研发时间,降低生产成本,提高轧制效率具有重要的意义。     

工艺参数对楔横轧厚壁空心轴不圆度的影响

采用有限元软件DEFORM-3D对楔横轧厚壁空心轴进行热力耦合数值模拟,得到了工艺参数对楔横轧厚壁空心轴不圆度的影响规律。结果表明,在成形角35°～45°、展宽角4°～7°、断面收缩率35%～65%、轧制温度900℃～1100℃时,轧件不圆度与成形角及断面收缩率的变化成反比,与展宽角及轧制温度变化成正比。采用H630楔横轧机进行轧制实验验证了有限元模型的正确性。模拟与实验结果证明,轧件横截面失圆是楔横轧成形厚壁空心轴类件常见的质量问题;变形区金属沿轴向的流动受到未变形金属的阻碍,是造成不圆度在轧件的对称面上最大并沿轴向逐渐减小的原因。研究结果为确定楔横轧厚壁空心轴的工艺参数提供了理论依据。     

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。     

Three-dimensional sheet metal continuous forming process based on flexible roll bending: Principle and experiments

To effectively manufacture three-dimensional sheet metal parts with various curvatures produced in small batch quantities, continuous sheet metal forming, a new flexible forming technology is being developed. This process employs an upper flexible roll and two lower flexible rolls as a forming tool, and the shape of a flexible roll can be changed in vertical direction. With the rotation of flexible rolls, the sheet metal is bent in longitudinal and transverse directions simultaneously and is formed continuously. In the present study, the three-dimensional surface of formed part is described by sweep surface based on the characteristic of the forming process and the arc-length parametric equation for describing continuous forming part is developed. The three-roll bending deformation of sheet metal in longitudinal direction is analyzed and the longitudinal curvature equation of the formed part is derived. The shape of flexible roll axis controlled at a number of points is represented by the cubic spline curve and the transverse curvature of the formed part after springback is then calculated piecewise. Typically experiments for forming concave shape surface and saddle-type surface have been performed, the experiment results are measured and analyzed by a binocular stereo vision measurement system, it is demonstrated that the formed surfaces are in good agreement with the desired shapes and the presented equations are useful for the continuous forming process design.     

An Incremental Roll Forming Process for Manufacturing Doubly Curved Sheets from General Quadrilateral Sheet Blanks with Enhanced Process Features

In order to manufacture a doubly curved sheet metal effectively, a flexible incremental roll forming process has been developed by adopting the advantages of the incremental forming process and the roll forming process by combining inherent flexibility of the incremental forming process and continuous deformation of the roll forming process. In the proposed roll forming system, a newly designed gripper system is attached in order to achieve automation and more precision manufacturing of the required sheet intended double curvature. The forming method has been further enhanced to form general quadrilateral blanks (including a square, a rectangle, a symmetrical trapezoid and an asymmetrical trapezoid, etc.) into doubly curved shapes by controlling the forming schedule developed by various experiments.     

楔横轧梯形螺纹轴模具关键参数的研究

楔横轧螺纹轴的金属流动规律和模具齿高等参数的确定对于模具设计意义重大.以轧制过程金属体积不变原理为前提,运用数学积分法求得模具齿顶高初值和轧件初始直径,进而设计模具孔型.对于设计的模具,采用DEFORM-3D有限元软件模拟轧制成形过程,得到较理想的梯形螺纹轴.该模拟结果验证了由齿顶高参数设计模具孔型进行楔横轧梯形螺纹轴轧制的可行性,为课题的深入研究提供了理论依据和参考价值.     

钢管三辊连轧成型过程的有限元分析

本文采用弹塑性、大变形和接触非线性有限元法,应用MARC软件对Y型三辊两道冷轧钢管的成型过程进行了分析,得到了钢管在成型过程中横截面的变形图和应力应变的分布规律.根据数值计算结果绘制了钢管冷轧成型过程中的轴向应力、环向和径向应力分布曲线,根据应力分布规律分析了对成品钢管直径和壁厚精度的影响因素.研究成果可以作为冷轧钢管成型工艺参数和成型辊设计的参考.     

带张力轧制铝管的有限元分析

采用大型非线性有限元软件ANSYS/LS - DYNA对三辊单机架轧管机轧制过程进行有限元模拟.分析了带张力轧制铝管时前张力、后张力对轧制力、芯棒轴向摩擦力以及金属延伸率的影响,为连轧机孔型设计及轧辊速度调整提供了理论依据.     

波纹冷卷成形的力学模型

介绍了波纹冷卷成形机的工作原理,对波纹成形的拉深过程和弯卷过程变形和应力分别进行了分析计算,冲压力与金属变形抗力、摩擦力、弯曲力等因素有关,弯曲应力分布多处于弹塑性状态。     

楔形长板辊轧过程中工艺参数的模拟优化

为了获得综合性能良好的某7A04铝合金楔形长板辊轧件,结合其复杂的形状结构特点,提出采用整体辊轧成形的工艺方案。通过在轧辊上开设一定形状的孔型,用来成形出满足尺寸要求的轧件。并对所提出的工艺方案进行有限元模拟,在控制其他工艺参数不变的条件下,通过模拟不同温度、辊轧角速度、摩擦系数条件下辊轧力的大小变化情况,总结出不同工艺参数下辊轧力的变化规律。最终确定了合理的辊轧工艺参数为:温度470℃,辊轧角速度0.1 r·s~(-1),摩擦系数0.7,且工艺试验得到的辊轧件与有限元模拟得到的辊轧件形状尺寸基本一致。     

Experimental and numerical analysis of helical-wedge rolling process for producing steel balls

The helical-wedge rolling (HWR) process is a new metal forming technique for producing spherical parts of various dimensions. In this paper, the overall details of the HWR process are described and the important process parameters that control the HWR process are systematically discussed. A new experimental method, developed under laboratory conditions, showed that the HWR process can produce spherical steel parts (balls) with high manufacturing quality. Numerical simulations of the HWR process were carried out using a commercially available FEM software (Simufact) to show the stress, strain, and temperature distributions in the rolled balls. In addition, the variation of forces and rolling moments during the process are analyzed. Based on the experimental and numerical investigations, the HWR technique has been found to be a viable process for enhancing the quality and productivity of formed spherical products.     

Explorative study of tandem skew rolling process for producing seamless steel tubes

The tandem skew rolling (TSR) process is a new metal forming technique for producing seamless steel tubes of various dimensions. In this paper, the overall details of the TSR process are described and the important process parameters that control the TSR process are systematically discussed. A new experimental method, developed under laboratory conditions, showed that the TSR process can produce seamless steel tubes with high manufacturing quality. Numerical simulations of the TSR process were carried out using commercially available FEM software (Deform) to show the stress, strain, and temperature distributions in the rolled tubes. In addition, the variation of forces and rolling torques during the process are analyzed. Based on the experimental and numerical investigations, the TSR technique has been found to be a viable process for enhancing the quality and productivity of formed tubular products.     

从动螺旋锥齿轮双锥辊辗压成形工艺参数优化

针对双锥辊辗压螺旋锥齿轮成形过程中型腔下模受力过大以及齿形充填高度不够的问题,首先,运用DEFORM-3D有限元软件对从动螺旋锥齿轮齿坯双锥辊辗压过程进行了模拟分析,研究了摩擦系数、辗压温度、凹模型腔进给速度对凹模型腔等效应力和Z方向成形齿高的影响;其次,采用正交试验设计方法,以凹模型腔等效应力和Z方向成形齿高为优化指标,得到了最佳工艺参数,并进行了数值验证;最后,通过数值计算分析以及与文献中研究结果进行比较分析,证明了从动螺旋锥齿轮双锥辊辗压成形工艺的可行性。结果表明:当摩擦系数为0.2、辗压温度为900℃、凹模型腔进给速度为2 mm·s~(-1)时,模具型腔受力最小,齿形的充填饱满,高度达到最高。     

辗环机自动轧制的初步研究

借鉴手动操作辗环机轧制环件的经验,分析辗环机轧制过程中环件的咬入条件、锻透条件、刚性条件与每转进给量的关系,以此确定关于每转进给量的理论设计方法和计算公式,为环件轧制的自动控制设计提供理论参考。