Mechanism-structural Design And Optimization Study Of Six-link Space Envelope Forming Equipment

Panel with thin wall and high rib is the key main bearing structure of aerospace equipment,widely used in the manufacture of rocket bodies,fuel storage tanks,warplane main bearing reinforcement frame,aircraft fuselage wall plate.The existing single-degree-of-freedom integral plastic forming manufacturing method is difficult to achieve its near-net forming because of the thin web,high tendons and large size span of thin-walled high-reinforced components.In response to the above-mentioned problems,this thesis proposes a new multi-degree-of-freedom space envelope forming method to achieve continuous partial near-net forming of thin-walled high-reinforced components.Based on the new method of space envelope forming,this thesis develops a heavy-duty multi-degree of freedom six-link parallel drive space envelope forming equipment,and carries out its mechanism-structure design and optimization research.The details of the study are as follows:(1)The kinematic transfer path of "servo motor-drive slider-ball-head linkage-mould" of the space envelope forming equipment is analyzed.The mapping relationship between mould position and drive slider position and linkage direction vector is revealed.The kinematic model of the space envelope forming equipment is established,and the coordinated motion control of multiple servo motors is realized.The kinematic simulation and experiment were carried out,and the results showed that the theoretical calculation and simulation results were in good agreement with the experimental results,which proved that the kinematic model of the space envelope forming equipment established in this thesis is reliable.(2)The rigid-flexible coupling kinetic model of the space envelope forming equipment mechanism is established,revealing the dynamic deformation behaviour of the ball-head connecting rod and the dynamic error change law of the mould,clarifying the influence mechanism of the mechanism parameters on the equipment stiffness,and proposing the optimal design method of the space envelope forming equipment mechanism.The results show that the mechanism optimization design method of space envelope forming equipment proposed in this thesis can effectively improve the mechanism stiffness,and the dynamic error of the mould is ≤10μm.(3)The distribution rules of the equivalent force and contact stress of the ball joint of the space envelope forming equipment are revealed,two deformation modes of the ball joint bending and tensile compression are found,and the criteria for judging the deformation mode of the ball joint is proposed.The finite element model of the frame of the space envelope forming equipment is established.The stress distribution law and elastic deformation law of the frame are revealed,and the optimized design method of the frame structure of the space envelope forming equipment is proposed.The results show that the optimized design method of space envelope forming equipment structure proposed in this thesis can effectively improve the structural stiffness,and the elastic deformation of the frame is ≤0.2mm.The research of this thesis has certain theoretical and engineering value for establishing the design theory of six-linked space envelope forming equipment and developing the technology of six-linked space envelope forming equipment.