Study On Laser Cladding Forming Technology Of Fairing Simulated Structural Parts

The fairing is an essential part of the engine of ultra-high speed aircraft such as aerospace.The fairing belongs to the special-shaped thin-walled complex structure,the traditional processing methods are mainly casting,welding,riveting,wire cutting,etc.,the use of traditional processing methods of low forming efficiency,high production costs,serious material waste.Laser cladding forming technology adopts layer by floor stacking method,which can be formed freely in three-dimensional space,and parts with various size shapes,complex structure and good organization can be formed without mould,which has become an advanced manufacturing technology used in aerospa123ce,industry and other fields in developed countries.In this paper,the 3D forming process of fairing analog structural parts is studied based on the technology of Hollow laser light feed-in powder cladding.The influence of laser cladding process parameters on melt morphology were studied,and the experimental data of melting channel width and height at different scanning speed and different defocusing amount were obtained respectively.The relationship between the height of the cladding layer and the scanning speed,the width of the cladding layer and the amount of processing defocusing are approximately linear within a certain range.The experimental data are linearly regressed to establish the height of the cladding layer and the scanning speed.Process parameter model between the width of the cladding layer and the amount of defocus.A stacking method with fractal stratification is proposed,which can obtain different heights according to different scanning speeds at different locations.The conformal stratification method can be formed directly without considering the complexity of the matrix,and the efficiency is obviously higher than that of the traditional horizontal stratification.Based on the stratified stacking method,the segmented shifting method is adopted to successfully form the thin-walled structure on the non-flat shaped surface and ensure the basic level of the upper surface.In order to solve the interference between the laser and the formed portion when scanning from a high position to a low position,the end of the thin-walled structure is collapsed,and the lowest position is used as the scanning start end,and the empty path and the laser start-stop position are set at the beginning and end of the scanning path.The method of deceleration solves the problem of uneven defects caused by repeated start and stop of the laser,and realizes the accumulation of thin-walled structures on the non-flat shaped base surface.By means of method and top sealing technology,the cladding forming fairing simulates the round table,cylinder and conical connection structure of the inner layer of the structural parts.The method can eliminate the step effect in the process of round table and cone forming,and the method of intermittent cladding and segmented scanning is used to solve the problem of the collapse of the cone caused by the thermal agglomeration effect of the cladding layer when the seal is piled up.The horizontal rib structure based on the round table and cylinder is formed by using the process method of forming thin-walled structure on the special-shaped base surface.Based on the oblique directional cladding process,the cylinder closure for the horizontal straight wall structure is carried out.The interference of the focusing laser beam and the end of the straight wall is avoided by using the oblique directional cladding method of the cladding nozzle deflection 16°,and the cylindrical closure of the horizontal straight wall structure is successfully completed by using the cladding method of the outer diameter of the hollow laser annular spot and the end of the straight wall.On the basis of the closed horizontal straight wall structure of the forming round table,the envelope closed melting forming of the inner Ring radiation multi-bar structure of the fairing simulation structure is carried out,and the whole forming of the fairing simulated structural parts is realized.The size test of the rectifier simulation structure is found that the overall quality of the forming parts is good and the size error range of each part is controlled within 8%.The microstructure analysis of the structure,rib strip and envelope cylinder closed junction of the rectifier is found that the microstructure is dense and uniform,and there are no defects such as cracks and stomata.The microhardness analysis of each part of the fairing simulated structural parts shows that there is little difference in the microhardness values of each part,and the microhardness is maintained between the 670?720HV.