凸模结构对大截面带筋方筒件挤压力的影响研究

目的 解决大截面铝合金带筋方筒构件在反挤压过程中成形力大的难题,实现在3 000 t压力机下成功制备内孔为665 mm×665 mm的大截面带筋方筒形构件。方法 提出了一种使用新型棱台凸模结构代替平凸模结构的方法,用主应力法得出了棱台凸模结构与平凸模结构的挤压力计算公式,对比分析了2种凸模结构反挤压成形力的大小,并用DEFORM有限元软件模拟分析了不同结构参数下的棱台凸模反挤压过程,最终进行工程试制,验证了反挤压工艺的可行性。结果 通过主应力法得出了方筒形件的变形力计算公式,得出棱台凸模结构反挤压成形力小于平凸模结构反挤压成形力,经模拟分析得出在反挤压过程中棱台凸模结构的最优结构参数为棱台斜角15°、棱台高度40 mm,并在3 000 t压力机上成功制得内孔为665 mm×665 mm的大截面带筋方筒形构件。结论 通过数值模拟分析可知,与采用平凸模结构相比,采用棱台凸模结构时的反挤压成形力降低了约13%,同时减少了挤压变形过程中的金属流动“死区”。经实验验证,在3 000 t压力机上成形了内孔为665 mm×665 mm的大截面带筋方筒形构件,实现了省力挤压。

Effect of Convex Die Structure on Extrusion Force of Large-section Ribbed Square Cylinder Parts

The work aims to solve the problem of large forming force in the reverse extrusion process of large-section aluminum alloy ribbed square cylinder parts, so as to successfully prepare large-section ribbed square cylinder parts with inner holes of 665 mm×665 mm under a 3 000 t press. A new type of bevel convex die structure was proposed to replace the plano-convex die structure, and the extrusion force calculation formula of bevel convex die structure and plano-convex die structure was obtained by the principal stress method, and the magnitude of the reverse extrusion forming force of the two convex die structures was compared and analyzed. Then, the reverse extrusion process of bevel convex die structure under different structural parameters was simulated and analyzed by DEFORM finite element simulation software, and finally the feasibility of the reverse extrusion process was verified by engineering trial production. The deformation force calculation formula of the square cylinder parts was obtained by the principal stress method, and the forming force of the reverse extrusion process of the bevel convex die structure was less than that of the reverse extrusion process of plano-convex die structure, and the optimal structural parameters of the bevel convex die structure in the reverse extrusion process were 15° angle of inclination and 40 mm height of bevel. At last, a large-section ribbed square cylinder part with an inner hole of 665 mm×665 mm was successfully prepared on a 3 000 t press. The deformation force calculation formula of the reverse extrusion process of two convex die structures is obtained by the principal stress method. Through numerical simulation analysis, it is concluded that the forming force of the large-section square cylinder part by the bevel convex die structure is reduced by about 13% compared with that by plano-convex die structure, and the metal flow "dead zone" in the extrusion deformation process decreases. Experiments have verified that large-section ribbed square cylinder parts with inner holes of 665 mm×665 mm can be formed on the 3 000 t press, which realizes labor-saving extrusion.