| The free bending technology is one of the revolutionary technological innovations in the field of plastic forming technology in recent decades.The technology combines advanced multi axis servo control technology with plastic forming technology,and realizes the forming of complex components through multi axis servo control of the trajectory of bending die.Compared with traditional tube bending technology,the technology has some significant technical advantages,such as high forming precision and easy control of resilience.The remarkable technological advantage will make the free bending technology be applied to the important military and civil fields,such as aerospace,nuclear power,automobile and ship.Therefore,study on the forming mechanism and forming process of three-dimensional free bending,research of effect of key technology parameters on the forming results,development of free bending equipment are of great significance to promote the development and progress of China's aerospace and other advanced manufacturing industries.Based on the basic principle of three axis free bending system,this paper has carried out in-depth research on the forming mechanism and forming process of tube free bending process,influence rule of key process parameters on the forming results and the development of related forming device.(1)Based on the basic principle of three axis free bending device,the free bending mechanism and forming process were analyzed.The distribution of stress and strain and the law of change of neutral layer on the tube blank in the free bending process were analyzed.A mathematical model of eccentricity-bending radius for free bending process was built and the analytical method of free bending process for complex components was designed.The distribution characteristics of the spatial trajectory of the forming system were obtained.(2)With the help of the finite element analysis software,finite element analysis model of free bending process was constructed.Firstly,reliability of the designed free bending process was verified by finite element simulation.Secondly,the influences of clearance between the bending die and tube,chamfer radius of guiding mechanism,friction coefficient and feeding speed on the forming results were analyzed by finite element simulation.(3)The free bending device was developed.The free bending device was developed and key components including spherical bearing,bending die and guiding mechanism were designed.The relationship between the offset U of the bending die and the bending radius R of the tube was studied by self-made device.Typical planar and three-dimensional free bending experiments were carried out. |
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