Research On Laser Cladding Forming Of Enclosed Impeller

Enclosed impellers have features such as closed cavities and internal flow passages,are widely used in engineering fields.Laser cladding forming is a rapid forming technology that has the advantages of being able to directly form complex metal thin-walled parts,short manufacturing processes,and high material utilization.The gap between the flow passages of the closely spaced blade structure is narrow,so there is a problem of positional interference.At present,there are many researches on the open impeller laser forming process,but there is no good laser cladding forming scheme for the closed structure of the enclosed impeller.In this paper,the closed cavity,thin-walled bridge,small blade spacing and other structural features of the enclosed impeller are used to study the cladding formation by hollow laser light feeding technology.In this paper,a laser cladding forming system is constructed,and a single pass experiment is carried out to study the basic process of cladding.The results show that the quality of the cladding layer is related to factors such as defocus amount,laser power,scanning speed and laser deflection angle.The presence of the laser deflection angle causes the highest point of the melt channel to deviate from the center.In the range of 0°-30°,the offset of the highest point of the cladding layer increases as the deflection angle increases.The influence of process parameters on the height of the cladding layer is:the powder feeding speed,the scanning speed,and the laser power;the influence on the width is:the defocus amount,the laser power,and the scanning speed.Aiming at the oblique cladding process,an oblique stratification method is proposed to establish a model of the relationship between the height of the diagonal stratified cladding and the actual lifting amount.The experiment verifies the feasibility of forming the straight wall by oblique misalignment.The deflection of the laser axis is within 30°,and it can form a straight wall with good verticality without obvious signs of lateral growth.The ANSYS simulation of the bridge contact model during the cladding process was carried out to simulate the stress field distribution.The results show that the higher the laser power,the greater the residual stress of the part.A path optimization first-end energy compensation scheme is proposed to solve the problem of the convex end and the end recess of the thin-walled member.The feasibility of the scheme was verified by adding the first and last flight strokes and the shifting section in the blade forming path.Aiming at the overall tight-closed impeller forming scheme,a sub-regional step-forming method is proposed,which uses different forming methods to realize different steps in different parts.The segment jump growth process not only overcomes the insufficiency of layer-by-layer stacking efficiency,but also overcomes the problem of stress concentration caused by laser drying between successively formed units,and improves the processing efficiency of the enclosed impeller.The enclosed impeller wheel cover structure is formed by the oblique bridging process,and the sealing problem in the enclosed impeller is solved.The combined process of adding and reducing materials is used to finish the enclosed impeller.The surface quality of the finished part is good,the size meets the design requirements,and the wheel cover and the blade are well fused,without cracking or gap.The bridging joint is densely organized,the grain size is uniform,and the hardness distribution of each part is uniform.