Study On The Powder Utilization Rate And Recycling In Laser Melting Deposition

Laser melting deposition technology has many advantages,such as small heat affected area,unlimited material,and the ability to process and manufacture complex structural parts,so it is widely used in the fields of parts repair,surface modification and complex structural parts manufacturing.However,the low powder utilization rate(30%-50%)is one of the main problems in the process of laser melting deposition with powder feeding.With the increase of manufacturing demand and energy price,it is of great significance to effectively improve the powder utilization capacity for reducing the production cost of laser melting deposition technology and improving its environmental benefits.In the case of meeting the requirements of processing performance,the improvement of powder utilization capacity includes two aspects: the improvement of powder utilization rate and powder recycling.In view of the current situation that the change rule of powder utilization rate in complex position processing is not clear,the model of powder utilization rate applicable to complex position and the research on powder recycling in laser melting deposition with Four-jet nozzle coaxial powder feeding need to be consummated,the on-line monitoring and probabilistic numerical modeling were used to study the utilization rate and the recycling of 316 L powder in laser melting deposition with coaxial powder feeding.The specific research contents are as follows:Firstly,considering the relative position between the substrate and the laser head,a powder utilization rate model for complex position was established.Based on the probability theory,the powder distribution density function of the substrate surface in the complex position of laser melting deposition process with coaxial powder feeding was constructed,and the powder distribution rule of the substrate surface when the relative position of the substrate and the laser head changes was analyzed.At the same time,the powder utilization rate model was established based on the powder distribution density function,and the powder utilization rate model was theoretically calculated by Matlab and was verified by weighing method.Secondly,the influence factors and the change rule of powder utilization rate in laser melting deposition technology were studied comprehensively.In this paper,the influence of process and path parameters on powder utilization rate was analyzed,and the change rule of powder utilization rate was studied when the relative position of the substrate and the laser head changes.Based on the powder distribution model when the relative position of the substrate and the laser head changes,the influence of the relative position of the substrate and the laser head on powder utilization rate was illustrated.The research provides important data support for the selection and optimization of process parameters and the establishment of energy consumption and environmental impact analysis model.Finally,the recycling ability of 316 L powder in laser melting deposition with Four-jet nozzle coaxial powder feeding was studied.The 316 L powder after deposition was treated by sieving,and the shape characteristics of 316 L powder with different recycling times were analyzed.Then 316 L powder with different recycling times was used for specimen processing.The changes of quality parameters,such as three-dimensional surface roughness,microstructure,microhardness and tensile strength,were analyzed.The results provide the empirical data support for the recycling of 316 L powder in laser melting deposition with Fourjet nozzle coaxial powder feeding.