Basic Research On Laser Cladding Surface Repair Technology Of Thin-walled Cylindrical Parts

Laser cladding is a metallurgical bonding cladding layer formed by melting the powder and substrate surface with a laser beam.It is mainly used for surface modification of materials,repair and remanufacturing of damaged parts and rapid prototyping.The repair quality is affected by many aspects during the repair process.This paper mainly focuses on the basic research of laser cladding surface repair technology for thin-walled cylinder parts.The influence of cladding path on the deformation of thin-walled cylinder was studied.The dynamic deformation of thin-walled cylinder was measured by displacement sensor,and the radial and axial dynamic deformation of cylinder under different cladding paths was studied;the deformation of cylinder outer wall and end face was measured by three-dimensional coordinate measuring instrument,and the laws of cylinder overall deformation and end face deformation were analyzed.The results show that in the unidirectional cladding scanning mode,the overall radial deformation of parallel scanning is less than that of circumferential scanning,and the axial deformation is 1/5 of that of circular scanning.In the continuous scanning,the radial deformation near the free end is larger than that of the parallel axis scanning,and the deformation far away from the free end is less than that of the parallel axis scanning.The final axial deformation is 28.5% larger than that of the parallel axis.Composite cladding scanning can effectively reduce the axial deformation of the cylinder.The influence of cladding direction and position on the deformation of thin-walled cylinder is studied.The cylinder with different cladding direction and position was scanned by hand-held three-dimensional scanner,and the whole deformation nephogram was analyzed.The results show that the influence of cladding direction on the deformation of thin-walled cylinder is mainly radial;when cladding at different positions of cylinder,the deformation difference is reflected in the influence of free end on radial and axial deformation,and the axial deformation gradually decreases when it is far away from the free end.Through the simulation of temperature field in different cladding directions,it is found that the cladding direction has a great influence on the temperature field.The temperature difference is closely related to the deformation,and the higher the temperature,the greater the deformation.The influence of cooling mode on deformation and stress of thin-walled cylinder is studied.The effects of natural cooling and spray cooling on surface morphology and cylinder deformation of cladding layer were observed.The results show that the deformation of cylinder is reduced by more than 40% after water cooling is applied,and the surface oxidation of cladding layer can be reduced and the surface quality can be improved.The influence of different cooling water temperatures on the deformation of thin-walled cylinder and the influence of residual stress measured by hole release method are studied.The results show that the maximum deformation occurs radially and axially at 0 C water temperature.Residual stresses caused by different cooling water temperatures are different and the larger the deformation,the smaller the residual stress.