3D Reconstruction Of Defect Morphology And Optimization Of Scanning Path For Laser Additive Repair

Laser cladding additive repair is a kind of surface repair technology,which can form one or more layers of micro cladding layer on the surface of the substrate.Through the laser cladding repair technology,the holes and cracks on the surface of the object can be filled,and the dimension and function of the defective parts can be re obtained or improved.With the development of laser,3D scanning and automation,laser cladding additive repair is widely used in aviation,automobile and other fields,facing a variety of processed products and metal parts,the requirement of forming accuracy is also higher and higher.The traditional laser cladding repair relies on manual operation,which limits the repair accuracy and efficiency.In order to achieve the design concept of high-precision repair of complex parts and improve the efficiency of laser cladding,the surface data of damaged parts are obtained by using the industrial three-dimensional laser scanner ATOS triple scan 16 m in this thesis to get the initial point cloud data of the part.Using Geomagic studio 3D model software to process the initial point cloud data,fitting the surface to obtain the solid model,using Boolean operation to obtain the defect location model.This thesis discusses the direct slicing method based on the solid model file.Firstly,slice with the minimum thickness and equal thickness,and then merge layer by layer according to the ladder width.The uniform and equal thickness layering method and adaptive layering method were used to complete the repair,and the Ademcad software was used to plan the layering and complete the simulation repair.The generated program was imported into the laser deposition forming system to realize the repair of the defect.A comparative experiment is designed to prove the feasibility of the laser cladding additive repair method proposed in this thesis.In the stage of point cloud data acquisition,the damaged object is scanned by using the three-dimensional laser scanner ATOS triple scan 16 m,and the accurate initial point cloud data of the measured object is obtained.The point cloud data is imported into the Geomagic studio three-dimensional software to remove noise points,redundant points,repair small holes and so on;In the phase of model reverse reconstruction,region detection,contour extraction and editing,construction and smoothing surface patches are performed on the processed point cloud data,and fitting surface to get solid model of damaged parts in STEP format.The model of the repaired area is obtained by Boolean difference between the damaged part model and the original model;In the repair phase,the principle of direct adaptive layering based on STEP format solid model file is studied.Firstly,the optimal direction of stratification is determined,and the intersection algorithm of solid model outline is introduced.The repaired model is divided into equal thickness sections with the minimum thickness that can be achieved by the laser cladding process,and then combined layer by layer with the maximum thickness required by the process according to the ladder width.Importing the layered results into the slicing software Adem CAD,which is used to plan the scanning path and simulate the repair.After simulation and verification,a fill scanning program is generated and downloaded to the Trulaser Cell 3000 precision laser deposition forming equipment.Finally,the repair of the damaged area is automatically completed.Machining a hole on the surface of an axial-shaped part to simulate a damaged part,the laser cladding repair technology proposed in this thesis is used to obtain the damage location model,and the laser cladding repair experiments with adaptive and equal thickness layers are carried out to achieve the repair of the parts.The repair time of equal thickness layer is 144 seconds and the number of layers is 8;the repair time of adaptive layer is 97 seconds and the number of layers is 6.The number of pores and metallographic morphology of the cladding layer were analyzed by nondestructive testing equipment and metallographic microscope.The results show that there are four pores in the cladding layer with equal thickness and two pores in the cladding layer with adaptive delamination,with the diameter is between10 and 10-55 μm.According to The National Standard of Common Nondestructive Testing ISO1004,the pores can be ignored,and there is no obvious crack and other defects in the cladding part.It can be seen that the laser cladding repair method in this thesis realizes the damage repair of parts through automatic equipment and software,effectively reduces the influence of manual operation on the repair process,and improves the repair efficiency of parts.