火箭贮箱箱底龙门铣焊装备静力学特性分析

Finite Element Analysis of Statics Characteristics of Gantry Milling and Welding Equipment for the Tank Bottom of Rocket

结合目前世界上最大的10 m级大直径运载火箭贮箱箱底搅拌摩擦焊接工艺需求,设计了用于大直径球面体搅拌摩擦焊的龙门式焊接装备。由于搅拌摩擦焊是通过被焊材料与高速旋转的焊接头进行摩擦产生热量并使其产生局部塑性化,当焊具沿着焊接界面向前产生位移时,塑性化的材料在焊接头处转动摩擦力的作用下由焊具的前部向后部流动,并在焊接头挤压下形成致密的固相焊缝。与熔焊不同的是,搅拌摩擦焊过程中需要焊接装备提供较大而且非常稳定的顶锻力和搅拌力,因此,龙门铣焊装备整体结构的力学特性分析非常重要。首先结合厚度为28 mm的铝合金材料2219在搅拌摩擦焊过程所需的作用力以及火箭贮箱箱底球面结构,建立焊接头的焊接过程力学方程,进而分析焊接过程中龙门铣焊装备的静力学特性。结果表明:所设计的龙门铣焊装备在焊接头扎入阶段、稳定焊接阶段的最大应力以及U形头最大变形量均与搅拌头和箱底夹角存在线性关系,而且从强度角度来说,目前设计的龙门式装备具有裕度过大的不足,可以改进。

Combining the process requirements of the world’s largest 10 m large-diameter carrier rocket tank bottom friction stir welding,a gantry type welding equipment for the large-diameter spherical body friction stir welding was designed.Due to friction stir welding,high-speed rotating welding head and the welded material are rubbed to generate heat and locally plasticized,when the welding tool moves forward along the welding interface,the plasticized material is flowed from the front of the welding tool to the rear under the action of the frictional force of the welding head,and a dense solid-phase weld is formed under the extrusion of the welding head.Unlike fusion welding,large and very stable upsetting force and stirring force are required in the friction stir welding process.Therefore,the analysis of the mechanical characteristics of the overall structure of the gantry milling and welding equipment is very important.Combining the force required by the 28 mm aluminum alloy material 2219 in the friction stir welding process and the spherical structure of the bottom of the rocket tank,the welding process mechanics equation of the welding joint was established,the static mechanical properties of the gantry milling welding equipment during the welding process were analyzed.The results show that the maximum stress and the maximum deformation of the U-shaped head of the designed gantry milling and welding equipment have a linear relationship with the angle between the stirring head and the bottom of the box during the welding head penetration stage,stable welding stage.In terms of strength,the current designed gantry-type equipment has the disadvantage of excessive margin and can be improved.