304不锈钢带筋管充液压形成形规律研究

发布时间：2018-05-31 04:22

本文选题：带筋管 + 充液压形　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：随着科学技术的进步和制造行业的高速发展,航空航天、武器装备等领域迫切需要通过减轻结构质量来实现轻量化,而轻量化对于节约能源、环境保护、提高机动性能等方面发挥着不可替代的作用。其中带环向加强筋的薄壁筒形件是一种比较常用的轻量化结构构件。但是由于其封闭截面形式、壁厚薄、截面复杂、尺寸大等要求带来一系列难题。目前的成形工艺都不能很好的解决这些问题,特别是对于整体成形。本文提出了一种新的成形工艺,将充液压形技术应用到成形带筋管中,实现了带筋管的整体成形。主要通过数值模拟结合实验对带筋管的成形规律进行研究,并对在成形过程中产生的缺陷和不足等进行力学分析。本文证实了带筋管应用充液压形技术整体成形的可行性。带筋管变形的实质是曲率的变化,这里设计了三种截面形状包括椭圆截面、半椭圆截面和矩形截面,通过数值模拟结合实验的方法,证明了带筋管应用充液压形技术成形的可行性。而且对三种截面形状的任意组合,也进一步证明了充液压形技术可以成形出复杂截面形状的制件。分析了带筋管在充液压形过程中的内压加载范围和内压加载方式。恒压加载路径下,充液压形件的材料填充性好、壁厚分布不均匀,应力波动大;线性加载路径下,充液压形件的材料填充性不好、壁厚分布均匀,应力波动小。根据大型薄壁带筋构件的需求选择线性加载方式。对带筋管在成形过程中产生的缺陷进行探讨分析。失稳主要分为三种类型:筋板倾倒、筋板失稳起皱以及薄壁管(无筋处)塌陷。倾倒主要发生在曲率增大处,失稳主要发生在曲率减小处,而塌陷主要发生在曲率为零的直壁段。对三种缺陷分别进行受力分析,失稳起皱和薄壁管塌陷的产生主要是因为当变形达到一定的变形量时,筋板或者薄壁管所受的环向应力大于其临界失稳应力,就会发生失稳缺陷。倾倒缺陷产生的原因主要是圆角处上下筋板所受的环向应力不均匀,进而产生了弯矩,当弯矩增加到一定程度会发生失稳倾倒的现象。对带筋管充液压形工艺中产生变形不协调现象进行理论分析。得出结论:成形件的筋板最外侧壁厚在直壁段增厚,圆角处减薄;筋板最内侧壁厚在直壁段减薄,圆角处增厚。薄壁管壁厚不发生变化。导致圆角处筋板内侧周长小于薄壁管处周长,产生“收腰”现象。模拟和理论分析得到的结论基本一致。分析了高厚比、摩擦系数、内压和回弹等对带筋管成形极限的影响。当高厚比的范围为0"fh/t㩳6时,可以成形。由于摩擦力的作用,上圆角大于下圆角填充速度。摩擦系数越大,壁厚差越大,成形极限下降。有内压的加载明显提高带筋管的成形极限。回弹对带筋管成形极限影响很小,可以近似忽略。
[Abstract]:With the progress of science and technology and the rapid development of manufacturing industry, aerospace, weaponry and other fields urgently need to reduce the quality of structure to achieve lightweight, and lightweight for energy conservation, environmental protection, Improving maneuverability plays an irreplaceable role. The thin-walled cylindrical part with circumferential stiffener is a kind of light-weight structural member in common use. However, due to its closed section form, thin wall, complex section and large size, it brings a series of difficulties. The current forming process can not solve these problems well, especially for the whole forming. In this paper, a new forming technology is proposed, which is applied to the forming of stiffened tube, and the integral forming of the stiffened tube is realized. In this paper, the forming law of the stiffened tube is studied by numerical simulation and experiment, and the defects and defects in the forming process are analyzed. In this paper, the feasibility of integral forming of stiffened pipe by hydraulic filling technique is confirmed. The essence of the deformation of stiffened tube is the change of curvature. In this paper, three kinds of cross-section including elliptical section, semi-elliptical section and rectangular section are designed, and the numerical simulation is combined with the experimental method. It is proved that it is feasible to apply hydraulic forming technology to the stiffened pipe. For any combination of three cross section shapes, it is further proved that hydraulic filling technology can form parts with complex cross section shapes. The internal pressure loading range and internal pressure loading mode of the stiffened pipe in the process of hydraulic filling are analyzed. Under the constant pressure loading path, the filling property of the hydraulic filling parts is good, the wall thickness distribution is uneven, and the stress fluctuation is large; under the linear loading path, the filling property of the hydraulic filling parts is poor, the wall thickness distribution is uniform, and the stress fluctuation is small. According to the needs of large thin-walled stiffened members, the linear loading mode is chosen. The defects in the forming process of the stiffened tube are discussed and analyzed. Instability can be divided into three types: toppling, wrinkling and collapse of thin-walled tubes. The toppling occurs mainly at the increase of curvature, the instability occurs at the point where the curvature decreases, and the collapse occurs in the straight wall with zero curvature. The stress analysis of three kinds of defects shows that the buckling and collapse of thin-walled tubes are mainly due to the fact that the circumferential stress of the stiffened plate or thin-walled tube is greater than the critical instability stress when the deformation reaches a certain deformation. There will be instability defects. The main reason for the toppling defect is that the toroidal stress of the upper and lower stiffened plates at the corner is not uniform and then the bending moment is produced. When the bending moment is increased to a certain extent the instability and toppling will occur. In this paper, the phenomenon of deformation disharmony in the hydraulic filling process of stiffened pipe is analyzed theoretically. It is concluded that the outermost wall thickness of the stiffened plate is thickened at the straight wall and the thickness of the innermost wall is thinned in the straight section and the corner is thickened at the corner. The wall thickness of thin wall pipe does not change. The inner circumference of the stiffened plate is smaller than the circumference of the thin-walled tube at the round corner, which leads to the phenomenon of "waistline". The results obtained by simulation and theoretical analysis are basically consistent. The effects of thickness ratio, friction coefficient, internal pressure and springback on the forming limit of stiffened tube are analyzed. When the ratio of height to thickness is in the range of 0 "FH / t? 6, it can be formed." Due to the effect of friction, the filling speed of the upper corner is greater than that of the lower corner. The greater the friction coefficient, the greater the wall thickness difference and the lower the forming limit. The forming limit of stiffened tube is obviously increased by loading with internal pressure. The springback has little effect on the forming limit of the stiffened tube and can be neglected approximately.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG394

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