金属板料单点渐进成形数值模拟及成形缺陷的研究

发布时间：2018-03-02 20:18

本文选题：单点渐进成形　切入点：回弹　出处：《陕西科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：金属板料单点渐进成形是一种在数控机床上通过计算机控制成形工具头运动的柔性制造技术,在钣金类件成形领域应用前景广阔。与传统的金属板料成形方式相比,单点渐进成形省去了模具制造的过程,因此,这种成形方式具有成本低、生产周期短的特点,特别适用于那些生产批量不大的产品。但是在对这种成形方式的进一步研究中,发现成形精度不足是制约单点渐进成形技术发展的关键,按照目前的科技水平与工艺技术最高能达到的精度为±3mm,但在工业应用领域要求成形件的精度为±0.2mm,这一精度要求严重制约了这项技术在先进制造领域的推广与应用。因此,本文重点对成形过程中的回弹进行了研究,因为回弹对成形件的精度影响最大,提出了减少回弹的方法;最后还对其它成形缺陷(厚度减薄、凹陷、破裂、压痕)进行了研究,提出了抑制这些成形缺陷的措施。本课题的研究内容如下:(1)单点渐进成形中理论问题的研究。主要分析了成形过程中的壁厚变化情况;同时对单点渐进成形中的主应力、主应变进行了分析,另外还对成形力进行了理论分析;最后通过正交实验对不同加工工艺参数条件下的成形力进行了测量,得出了成形力与加工工艺参数的关系。(2)利用ABAQUS对渐进成形过程进行了数值模拟。分别模拟了成形角为30°、45°、60°,层间距为0.5mm、1.0mm、1.5mm,成形工具头半径为3mm、4mm、5mm条件下的应力、应变、位移。(3)采用实验方法对单点渐进成形中的回弹进行了重点研究。首先,单独研究了主轴转速对回弹量的影响;然后,对不同形状的成形件的回弹量进行了研究,选取了三种典型的制件:外凸形、圆锥形、内凸形;最后利用正交实验对成形角、层间距、进给速度、加工深度这四个因素对回弹量的影响进行了研究,通过以上研究得出了这些因素对成形件回弹量的影响。(4)对渐进成形过程中的其它一些成形缺陷进行了研究。研究了成形角对成形件壁厚的影响;正交实验研究了不同加工工艺参数条件下的最大凹陷值;另外还研究了板料表面的破裂、压痕、金属堆积现象,且提出了相应的抑制这些缺陷的措施。(5)回弹现象是单点渐进成形过程中一个不可避免的现象,减小回弹的方法很多。本文,主要研究了采用负补偿方法来减小回弹,这为后期进行相关研究提供了参考依据。
[Abstract]:Single point incremental forming of sheet metal is a kind of flexible manufacturing technology which can control the movement of forming tool head by computer on NC machine tool. It has a broad application prospect in sheet metal forming field. Single point incremental forming eliminates the process of die manufacturing, so it has the advantages of low cost and short production cycle, and is especially suitable for those products with small batch production. However, in the further study of this kind of forming method, It is found that the lack of forming precision is the key to the development of single-point incremental forming technology. According to the present level of science and technology, the maximum accuracy of the technology is 卤3mm, but the precision of forming parts is 卤0.2mm in the field of industrial application, which seriously restricts the popularization and application of this technology in the field of advanced manufacturing. In this paper, the springback in the forming process is studied, because the springback has the greatest influence on the precision of the forming parts, the method of reducing the springback is put forward, and the other forming defects (thickness thinning, depression, fracture, indentation) are also studied. The research contents of this paper are as follows: 1) the theoretical problems in single point progressive forming are studied. The variation of wall thickness in forming process and the principal stress in single point progressive forming are analyzed. The main strain is analyzed, and the forming force is analyzed theoretically. Finally, the forming force under different processing parameters is measured by orthogonal experiment. The relationship between forming force and processing parameters is obtained. The numerical simulation of progressive forming process is carried out by using ABAQUS. The stress and strain are simulated under the conditions of forming angle 30 掳45 掳60 掳, layer spacing 0.5 mm 1. 0 mm 1. 5 mm, and the radius of forming tool head 3 mm / 4 mm / 5 mm, respectively, when the forming angle is 30 掳/ 45 掳/ 60 掳, the layer spacing is 0. 5 mm / 1, and the radius of forming tool head is 3 mm / 4 mm / 5 mm. Displacement. 3) the springback of single point progressive forming is studied by experimental method. Firstly, the effect of spindle speed on springback is studied separately; then, the springback of different shapes of forming parts is studied. Three kinds of typical parts are selected: convex shape, conical shape and inner convex shape. Finally, the effects of four factors, such as forming angle, interval between layers, feed speed and machining depth, on springback are studied by orthogonal experiment. The influence of these factors on the springback of the forming parts is obtained. Some other forming defects in the process of progressive forming are studied. The influence of the forming angle on the wall thickness of the forming parts is studied. In addition, the fracture, indentation and metal accumulation on the surface of sheet metal were studied by orthogonal experiment under the conditions of different processing parameters. It is suggested that the springback phenomenon is an inevitable phenomenon in the process of single point progressive forming, and there are many methods to reduce the springback. In this paper, the negative compensation method is mainly used to reduce the springback. This provides a reference for the later research.
【学位授予单位】：陕西科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG306

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