Neural Network Optimized Closed-loop Control Of The Three-Dimensional Closed Impeller Cover Forming Process With Laser Inner Powder Feeding

Laser Cladding Forming(LCF)is a synchronous metal additive manufacturing technology of laser beam and metal powder.With the progress of laser cladding technology,the cladding forming of open impeller has been realized.However,there are still many difficulties in laser cladding of closed impeller.In the process of realizing the cladding of wheel cover,the laser cladding nozzle and the generated impeller components will have physical interference,and the traditional normal processing method is no longer applicable;In the complete laser cladding process,the number of cladding layers is more than 100.The current laser cladding technology mainly selects the molten pool for temperature detection and traditional image detection to predict the height.Most of the feedback systems have not been established,resulting in the instability of the height of the cladding layer,which will cause the collapse of the line;In the process of cladding,to realize the efficient lapping of wheel cover and existing blades,the current technology is mainly tenon or welding,and there is less research on the forming process of laser cladding direct lapping intersection.In this paper,the difficulties mentioned above have been studied.First,based on the laser internal powder feeding cladding nozzle,the laser cladding oblique orientation processing technology has been investigated.The influence on the quality of the cladding layer under the cross change of the substrate tilt angle and the cladding nozzle tilt angle is investigated.The laser cladding performance is investigated by tilting the cladding nozzle under different substrate tilt angles.The experimental results show that when the substrate and the horizontal plane are 90°,the vertex offset decreases first and then increases with the increase of the nozzle tilt angle,and the smaller vertex offset can be obtained by controlling the cladding nozzle tilt angle at 15±1°;When the angle is not 90°,the vertex offset of the cladding layer first increases and then decreases with the increase of the nozzle tilt angle.The inclination angle of the cladding nozzle should be 5±1° to obtain a smaller vertex offset.A complete closed-loop control system is built based on machine vision.The initialization design of the side-axis camera was completed through the self-designed fixture and the calibration of the camera system.Through the algorithm denoising and enhancement of the molten pool image obtained under the five defocusing parameter settings of-2.4mm to-3.6mm when the laser power is 1200W,the scanning speed is 8mm/s,and the metal powder conveying rate is 45.9g/min,the ConvNeXt neural network five-classification task training was carried out,and the 96.75%model obtained was deployed on the PC,According to the Euclidean distance design algorithm,the classification results are continuously smoothed,and the classification result sequence is input to the KUKA robot by TCP/IP to realize the adaptive adjustment of the lifting amount to complete the complete closed-loop control of the laser cladding system.Based on the completed laser cladding oblique orientation technology and machine vision closed-loop control system,the closed impeller laser cladding processing experiment was carried out.In the experiment,the cladding and lapping technology of wheel cover and blade was studied.According to the powder dispersion model and the law of mass conservation,the intersection model is established,and the spatial morphology model of the cladding layer is used as the boundary condition for solution.The acceleration process technology of the intersection of the impeller blade is established,which realizes the effective overlap of the impeller and the blade,and completes the closed impeller forming.The overall hardness of the fomed part of the closed impeller wheel cover is between 281.25 and 291.23HV0.3,with a smooth and bright surface,without macroscopic cracks or inclusions,and a uniform and dense microstructure.The research in this paper can provide a manufacturing technology with laser cladding as the core for the production of closed impeller.