内环筋薄壁壳体内旋压工艺有限元模拟与试验研究

发布时间：2018-07-23 18:45

【摘要】：带内环筋、薄壁是曲母线筒形件广为采用的结构形式,是在保证零件刚度、强度不降低的情况下减轻重量的首选结构形式。本课题以铝合金壳体为研究对象,研究带内环向加强筋薄壁壳体零件的内旋压成形,通过有限元数值模拟和试验研究,分别对小端起旋和大端起旋两种内旋压成形工艺及制品的组织与性能进行了研究。采用ABAQUS软件对异形薄壁壳体小端起旋和大端起旋两种内旋压成形工艺进行了有限元模拟,对其旋压力和变形情况进行了计算分析。采用小端起旋的预成形-终成形旋压工艺,可获得变形均匀的圆筒形薄壁件。这种旋压工艺的径向旋压力最大,轴向旋压力次之,切向旋压力最小。与径向旋压力相比,切向旋压力基本可以忽略不计。在壳体大端的后端框和中间段蒙皮部分的旋压成形过程中,其旋压力存在平台区,成形过程平稳;在壳体小端前端框部分的旋压成形过程中,旋轮的轴向行程越大,减薄率越大,旋压力越大,壳体旋压成形的最大旋压力出现在这一过程中。若将大端固定,可以实现扩径旋压,但在壳体的蒙皮与前端框的过渡区域出现变形不稳定区。通过对某内环筋薄壁壳体小端起旋和大端起旋两种旋压工艺试验,分别研究了大端和小端起旋两种内旋压工艺的成形规律。采用大端和小端起旋工艺成形曲母线薄壁壳体时,存在如下两种工艺:一是在实现扩径的同时,壁厚基本保持不变;二是在扩径的同时,壁厚进行减薄。对于大端起旋,当模具半锥角小于毛坯半锥角时,其壁厚减薄规律应符合正弦律,而小端起旋的壁厚减薄规律不受正弦律约束。根据正交试验结果确定的内旋压成形工艺参数分别为:进给比0.6mm/r,减薄率25%,旋轮圆角半径6mm,旋轮安装角25°。通过旋压试验确定的带内环筋薄壁壳体小端起旋工艺流程为:毛坯下料→毛坯加工→退火处理→预成形→淬火→终成形→零件加工。与之对应的旋压工艺参数分别是:预成形的最大壁厚减薄率25%,终成形的最大减薄率为10%;旋轮圆角半径6mm,旋轮进给比0.6mm/r,主轴转速50r/min。试验件的壁厚差为±0.05mm,圆度为0.15mm。对某制品薄壁壳体旋压试验件蒙皮段的微观组织和力学性能进行了测试。测试结果表明,退火-旋压工艺成形的制品晶粒比较细小,尺寸在1μm~5μm之间,但强度不满足设计要求;而预成形-终成形结合中间淬火工艺成形制品的晶粒较大,尺寸在15μm~20μm之间,总变形量越大,晶粒尺寸越细小,其抗拉强度满足360MPa的设计要求;内旋压所有试验件在切向上均有纤维组织产生,总变形量越大,切向纤维组织越明显;退火—旋压工艺成形的制品残余应力值较小,预成形-终成形结合中间淬火工艺旋压制品残余应力值相对较大,旋压制品的残余应力均为压应力。对内环筋薄壁壳体内旋压成形工艺的有限元数值模拟和试验研究,不仅为确定某铝合金薄壁壳体旋压成形工艺、实现批量生产提供了依据,而且也为更好地解决带内环向加强筋薄壁类壳体零件的旋压成形问题提供了参考。
[Abstract]:With inner ring bar and thin wall is a structural form widely used for curved busbar shaped parts. It is the first choice to reduce the weight of the parts under the condition of ensuring the rigidity of the parts and the strength is not reduced. This subject takes the aluminum alloy shell as the research object, and studies the internal spinning forming of the thin-walled shell parts with inner ring stiffeners, through the finite element numerical simulation and test. In this study, the microstructure and properties of two internal spinning processes and products were studied, respectively. The ABAQUS software was used to simulate the two internal spinning processes of the small end spin and the large end spin forming, and the rotating pressure and deformation were calculated and analyzed. The rotary pre forming and final forming spinning process can obtain uniform cylindrical thin-walled parts. The radial pressure of the spinning process is the largest, the axial rotation pressure is the second, the tangential spin pressure is the smallest. Compared with the radial rotation pressure, the tangential spin pressure can be ignored. The spinning of the rear end frame and the middle section of the middle section of the large end of the shell is formed. In the process, the rotating pressure has the platform area and the forming process is stable. In the spinning process of the front frame part of the small end of the shell, the larger the axial stroke of the rotary wheel, the greater the thinning rate, the greater the rotation pressure, the maximum rotation pressure of the shell spinning forming in this process. If the large end is fixed, the enlargement spinning can be realized, but the skin of the shell is covered by the skin. The deformation instability zone appears in the transition region of the front end frame. Through the two spinning process tests on the small end spin and the large end spinning of a thin wall shell of a inner ring, the forming rules of the two internal spinning processes of the large end and the small end spin are respectively studied. There are two processes as follows: when the large end and the small end spin process is used to form a thin-walled shell of the curved busbar, the following two kinds of processes are present: One is that the wall thickness is basically the same while the enlargement is realized; two is the thickness reduction of the wall thickness at the same time when the diameter is expanded. When the large end is whirling, the thinning law of the wall thickness should conform to the sine law when the half cone angle is less than the semi cone angle of the blank, and the thinning law of the wall thickness of the small end whirling is not restricted by the sine law. The internal rotation determined according to the orthogonal test results. The process parameters of pressing forming are as follows: feed ratio 0.6mm/r, thinning rate 25%, rotary wheel corner radius 6mm, rotary wheel installation angle 25 degrees. The small end spinning process of inner ring stiffened thin-walled shell with inner ring reinforced by spinning test is: blank blanking, blank processing, annealing treatment, pre forming, quenching, final forming and parts processing. The art parameters are the maximum thinning rate of pre forming wall thickness 25%, the maximum thinning rate of final forming 10%, rotary wheel corner radius 6mm, rotary wheel feed ratio 0.6mm/r, the wall thickness difference of 50r/min. test parts of spindle speed is + 0.05mm, and the roundness is 0.15mm. to test the microstructure and mechanical properties of a thin-walled shell spinning test piece. The test results show that the grain of the products formed by the annealing spinning process is relatively small, the size is between 1 m~5 and m, but the strength is not satisfied with the design requirements, while the grain size of the pre forming end forming combined with the intermediate quenching process is larger and the size is between 15 Mu m~20 mu m, the greater the total deformation, the smaller the grain size and the tensile strength to meet 360MPa. All the testing parts of the internal spinning are produced in the tangential direction, the greater the total deformation is, the greater the amount of the total deformation, the more obvious the tangential fibers are. The residual stress of the products formed by the annealing spinning process is smaller, the residual stress value of the pre forming end forming combined with the intermediate quenching process is relatively large, and the residual stresses of the spinning products are all The finite element numerical simulation and experimental study on the spinning process in the inner ring stiffener shell not only provide the basis for determining the spinning process of a thin-walled shell of an aluminum alloy and realizing the mass production, but also provide a reference for the better solution of the spinning forming of the thin-walled shell parts with inner ring stiffeners.
【学位授予单位】：燕山大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TG306;TG146.21

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