无压边拉深凹模成形曲面的优化

利用优化方法对拉深凹模成形曲面进行研究,建立含有工件稳定条件为约束的优化模型。其优化解可以避免工件起鼓,保证具有最小的F_(max)和得到最大的拉深比。

无压边拉深凹模成形曲面的优化

一、前言无压边拉深时,以采用曲面凹模为宜。用曲面凹模拉深与普通拉深相比,工件的成形特点完全不同。工件沿凹模的曲面流动,光由平板形成锥形件,最后拉深成筒形件。在这一过程中,很难象普通拉深那样采用压边装置来防止工件起皱。要防止起皱失稳,必须依赖凹模的曲面形状。此外,凹模的曲面形状对拉深力及摩擦、磨损等也有影响。因此,凹模曲面的形状是影响拉深比以及产品质量和模具寿命的关键因素。本文利用优化方法,为寻找最合理的凹模曲面形状进行了理论性研究。

楔横轧轴肩的成形曲面的设计

此文分析在二辊楔横轧中轧制各类轴肩的过程。在假想工件轴端固定的图上确定楔侧面截面轮廓形状,再通过叠加轴向刚性移动量确定各截面实际位置,比较直观简便地设计出轧制轴肩的辊面上的成形曲面。最后归纳了设计步骤。

用MasterCAM构建自由成形曲面的方法与应用

随着现代工业的发展,越来越多的产品丰富着我们的生活,新产品不断开发研制,这些产品除了应用新技术、新工艺外,还对形体造型提出更高的要求。曲面造型,它能描绘立体造型的表面形状,但不记录曲面所包围的空间数据。利用曲面造型可以产生目前实体理论无法产生的造型,已广泛运用于汽车、造船和航天工业等领域。

波形弹簧成形模曲面的在线加工

阐述了波形弹簧成形模曲面的确定及其数控加工程序的编制方法、加工工艺过程 .在简易数控铣床上 ,通过上位计算机的控制 ,利用数控机床RS2 32接口与计算机进行数据传输 ,实现了波形弹簧模具形面的在线加工 .为利用简易数控机床加工自由曲面提供了一条可行的途径 .

金属板材的复杂曲面复合成形加工方法

在我国汽车、船舶、飞机等制造工业高速发展的影响下,各种产品更新换代的速度更快,产品品种和类型也越来越多,对于板材弯曲成形的需求量也越来越大。和以往的薄板冲压成形相比较来说,复杂曲面厚板成形一直以来都是金属板材成形领域的一大挑战。不同板材成形技术的优势和缺点各不相同,为了更好地发挥出不同成形加工方法的优势和作用,很多学者对其进行了不断地研究,为板材成形精度的提升奠定了很好的基础。基于此,本文对金属板材的复杂曲面复合成形加工方法进行了分析研究,对复杂曲面复合成形加工方法进行了详细分析研究。希望可以为提高复杂曲面复合成形精度的提升提供一些有价值的参考。

数控成形铣削准双曲面齿轮加工研究

鉴于目前数控加工的高效率、高质量的特点,探讨了采用指形铣刀铣削成形法准双曲面齿轮的可行性,建立了成形铣削准双曲面齿轮大轮的数学模型,将基本加工调整数据转换到立式加工中心上,得出机床、刀具、夹具安装调整参数,编制相应的数控加工代码,结合具体轮坯参数进行铣削仿真试验和铣削加工试验,获得了一种新的加工方法。

柔性滚弯成形技术研究进展

柔性滚弯成形技术主要用于制造形状多样化、生产批量小的复杂薄壁曲面制件,广泛运用于飞机、船舶、火箭等运载工具。总结了柔性滚弯成形技术在国内外的研究现状,介绍了刚性辊滚压橡胶垫的单轴柔性滚弯成形技术;刚性辊和柔性辊相互作用或者双柔性辊相互作用的双轴柔性滚弯成形技术;可弯曲、可调节的三柔性辊相互作用的曲面连续成形技术。对新型工艺技术的基本原理以及工艺特点进行了分析和总结。

波纹簧弯曲模设计

通过对波纹簧特点的分析,结合Pro/E软件及计算公式对波纹簧弯曲前毛坯尺寸、回弹半径及回弹角度进行详细的分析和计算,并采取了定位套进行定位,巧妙地实现了凸、凹模成形曲面的设计,最终满足了波纹簧的设计要求。

Effect of prestressed ultrasonic peen forming parameters on bending curvature and spherical deformation of plate

The elastic prestressed ultrasonic peen forming(UPF)was adopted in order to solve problems of insufficient bending deformation and large spherical deformation of plate during free UPF.The theoretical analysis of prestressed UPF and the influence of elastic prebending moment on deformation were analyzed.Spherical deformation coefficient was defined to quantificationally describe the spherical deformation.Experiments were conducted to compare the differences between free UPF and prestressed UPF processes and the effects of processing parameters on bending curvature and spherical deformation coefficient were studied.The results show that peening trajectory in chordwise direction is beneficial to enlarging spanwise bending deformation and decreasing spherical deformation coefficient.Large prebending curvature is helpful to increase spanwise bending deformation and decrease chordwise deformation,thereby obviously decreasing spherical deformation coefficient.Large spanwise deformation can be obtained under large firing pin velocity,small plate thickness and small offset distance.Large firing pin velocity plays a positive role in decreasing spherical deformation,while plate thickness and offset distance have little effect on it.Above all,prebending curvature and peening trajectory are the most important factors during prestressed UPF process.This study provides guidance for parameters optimization of prestressed UPF for wing plate with large thickness.

Optimization of press bend forming path of aircraft integral panel

In order to design the press bend forming path of aircraft integral panels,a novel optimization method was proposed, which integrates FEM equivalent model based on previous study,the artificial neural network response surface,and the genetic algorithm.First,a multi-step press bend forming FEM equivalent model was established,with which the FEM experiments designed with Taguchi method were performed.Then,the BP neural network response surface was developed with the sample data from the FEM experiments.Furthermore,genetic algorithm was applied with the neural network response surface as the objective function. Finally,verification was carried out on a simple curvature grid-type stiffened panel.The forming error of the panel formed with the optimal path is only 0.098 39 and the calculating efficiency has been improved by 77%.Therefore,this novel optimization method is quite efficient and indispensable for the press bend forming path designing.

Automatic recognition of intersecting features of freeform sheet metal parts

This paper presents an approach for recognizing both isolated and intersecting geometric features of freeform surface models of parts,for the purpose of automating the process planning of sheet metal forming.The developed methodology has three major steps:subdivision of B-spline surfaces,detection of protrusions and depressions,and recognition of geometric features for sheet metal forming domain.The input geometry data format of the part is based on an IGES CAD surface model represented in the form of trimmed B-spline surfaces.Each surface is classified or subdivided into different curvature regions with the aid of curvature property surfaces obtained by using symbolic computation of B-spline surfaces.Those regions satisfying a particular geometry and topology relation are recognized as protrusion and depression(DP) shapes.The DP shapes are then classified into different geometric features using a rule-based approach.A verified feasibility study of the developed method is also presented.

Principle and theoretical analysis of continuous roll forming for three-dimensional surface parts

Continuous roll forming(CRF) is a novel forming process for three-dimensional surface parts,in which a pair of bendable forming rolls is used as sheet metal forming tool.By controlling the gap between the upper and lower forming rolls,sheet metal is non-uniformly extended in the longitudinal direction while it is bent in the transverse direction during the rolling process.As a result,longitudinal bending is gained and a doubly curved surface is formed.With the rotations of the forming rolls,the sheet metal is deformed consecutively,and a three-dimensional surface part is shaped continuously.In this paper,the mechanism of the three-dimensional surface formation in CRF is set forth.Through theoretical analysis of the CRF process,the governing equations for the bending deformation in rolling process are presented.Based on the simplification on the deformation and material model,the formulation to calculate the longitudinal bending deformation is derived,and the methods to design the compression ratio and the roll gap are given,the effects of compression ratio of rolling and the width of blank sheet on the longitudinal bending curvature are analyzed.The forming experiments on typical surface parts and measured results show that forming results with good precision can be obtained by CRF process.