Research On New Cladding Nozzle Design And Laser Cladding Process Simulation

With the rapid development of science and technology,people have more demand and exploration for metal additive manufacturing.At present,as a linchpin component of additive manufacturing equipment,cladding nozzle still has many shortcomings in the application of heat source and the selection of powder feeding mode.Therefore,a new cladding nozzle with compound laser beam as heat source and multi-channel powder feeding in inner and outer rings is designed in this thesis.The thermal deformation of the nozzle is researched by numerical simulation.The powder flow and the temperature field and flow field in the process of laser cladding are simulated and analyzed.The accuracy of the simulation results is verified by machine learning algorithm.The main research contents are as follows:In order to improve the processing efficiency and the forming quality of the workpiece,a new type of cladding nozzle is designed.The heat source part of the nozzle adopts a new composite laser beam(composed of single laser beam in the center and three laser beams on the outside).The powder feeding part adopts multi-channel powder feeding channels with six channels in the inner ring and nine channels in the outer ring.After simulating the water cooling effect,it is determined that the water cooling channel is loop type,and the changes of parameters such as temperature,flow rate and pressure of cooling water are obtained.Through simulation analysis,the thermal stress and maximum deformation of the nozzle under working state are researched,and it is known that the maximum deformation is0.15 mm,and the maximum equivalent stress is 650 MPa,and the maximum equivalent effect becomes 0.0020319.Aiming at the conveying and spraying of metal powder in additive manufacturing,the movement of powder particles and the aggregation process of powder flow are researched.By simulating the powder feeding process of six way powder feeding in the inner ring,nine way powder feeding in the outer ring and the cooperation of the inner and outer rings,we can know that the maximum velocities of powder flow under different conditions are 5.053m/s,2.682m/s and 4.988m/s.And the powder spraying range and aggregation effect are known as well.Then we analyze whether it meets the processing requirements,and optimize the parameters of the structural deficiencies.The neural network model is used to fit and verify the simulation result data,and we know that the minimum error value is 0.0000085244,and the optimal overall fitting degree is 0.99999.These parameters are obtained to determine the accuracy of the simulation process.Through the simulation of laser cladding process,the melting deposition of powder under the action of laser at high temperature is researched.Through the simulation of powder cladding when the central single laser beam,the outer three laser beams and multiple laser beams work together,we can konw that the maximum temperature are 2400?,2656.7? and 2916.8? respectively,and the maximum equivalent residual stress under single laser beam,three laser beams and multiple laser beams are obtained to analyze whether the hot-melt effect is ideal.The simulation results of laser and powder cladding are verified by using the neural network model with multiple hidden layers.