Analysis And Research On Welding Stress Of Thin Plate Pressure Vessel

Pressure vessel is widely used in production and life.But it is easy to leak due to pressure and cause safety accidents.Therefore,safety is the first factor of pressure vessel production.At present,the research on the pressure vessel of thin plate(0.4-4mm thickness)is less,but the decrease of wall thickness leads to the decrease of strength,which has a great influence on the safety of the key structure of the thin plate pressure vessel.Therefore,it is necessary to analyze the stress distribution and change in the manufacturing process of thin plate pressure vessel.This paper mainly takes the thin plate pressure vessel liquid storage tank produced by a special equipment manufacturer as the research object.Aiming at the cylinder weld,the thermal stress change in butt welding process of sheet metal is studied by ANSYS finite element software.Used to guide production and ensure product safety.There are the following aspects of research:1.The influence of heat input and welding speed on welding temperature and stress is studied.The welding temperature field is simulated by simulating the heat input and welding speed.The best simulation parameters of welding temperature field and the distribution of welding temperature field under the influence of these parameters are obtained by comparing the welding temperature field data under different parameters.Through the analysis of welding temperature field and stress field,the change of instantaneous stress field and the distribution and trend of residual stress after cooling are obtained.2.The results of the welding stress test under the same process parameters are compared to verify the feasibility of the simulation method.The Gauss surface heat source equation used in this paper is reasonable and can be used for the simulation of butt welding joints of thin plates.The welding heat input parameters and boundary conditions are set correctly,which lays the foundation for the analysis of the weld of thin-walled pressure vessels.3.Based on the research and analysis of thin plate butt welding,the numerical simulation analysis of transverse butt welding of thin plate pressure vessel cylinder was carried out.The results show that: with the movement of welding heat source,the temperature field experiences the process of instability stability instability.Because of the transient heat source movement and heat transfer effect,there is a temperature rising region slowly at the head and end of the welding joint,which affects the melting effect of metal.When analyzing and comparing,the welding joint at the first and the end ends is avoided as far as possible.During butt welding,the stress of butt welding is mainly concentrated along the weld direction,and the stress in the pool is the lowest.After cooling,the residual stress increases due to the movement of crystals.Finally,the gradient of stress field increases at the end of the weld,and the gradient range of the Middle stress field is basically unchanged;The residual stress of the transverse weld of the cylinder is mainly concentrated in the weld area and the welding heat affected zone,and the maximum value in the near weld area is 320 MPa,The further away from the weld,the lower the residual stress.The maximum residual stress is far less than the allowable stress of the material,which proves that the welding parameters are safe and effective.Compared with the experimental results,it is basically consistent,which proves that the analysis method in this paper is suitable for the butt welding analysis of thin plate pressure vessel.