A Study On Quality Monitoring Of Laser Metal Deposition Additive Manufacturing Based On Spectral Analysis

Laser deposition additive manufacturing technology has developed rapidly and is widely used in various industries.It has put forward higher requirements for the dimensional accuracy and quality of molded parts,and how to reduce the cost of additive manufacturing has become an urgent problem to be solved.Therefore,it is of great theoretical significance and application value to study the quality monitoring of the additive manufacturing process.Improving the quality control and the utilization of metal powder of the additive process and improving the utilization of metal powder,the size and defects of the cladding layer during the additive manufacturing process are monitored,and the reusability of the recycled powder is studied.On the one hand,in the process of 316 l additive manufacturing,spectrum monitoring technology is used to accurately predict the size of the cladding layer,and in the process of laser additive manufacturing of 316 L stainless steel complex molded parts,the use of spectral diagnostic technology and coaxial visual diagnostic technology to monitor defects in the additive process.On the other hand,in the process of laser additive manufacturing of316 l stainless steel,collect unmelted metal powder as recycled powder,analyze the structure and mechanical properties of the virgin powder and recycled powder,and study the spectral characteristics of powder recycling influences.First,the orthogonal experiment and the controlled variable method experiment are designed separately,mainly by changing the process parameters(laser power,scanning speed and powder feeding rate)to obtain different single-pass single-layer cladding layer sizes(layer width,layer height and penetration)),in the process of laser additive manufacturing,it was found that the width and depth of the cladding layer increased with the increase of laser power,and the scanning speed and powder feed rate decreased;the height of the cladding layer with the laser power The powder feed rate increases and the scanning speed decreases and decreases.The regression analysis method establishes a regression model of the cladding layer size and process parameters.The multiple nonlinear regression model can accurately predict the cladding layer size;Further establish the cladding size and single spectral characteristics(the radiation intensity of the plasma,electron temperature and electron density)fitting prediction curve and the neural network algorithm to establish the spectral characteristics and cladding layer size model comparison of the accuracy of the prediction results,Found that the neural network prediction model has higher accuracyThen,the 316 L stainless steel powder was additively manufactured for complex walls,and the spectral information and visual information were collected in real time.It was found that when the defects in the process of additively manufacturing complex walls were due to parameter mismatches or other reasons,the radiation intensity of the plasma,The temperature of the electron and the area of the molten pool obviously fluctuate.The weighted average algorithm is further used to fuse spectral information and visual information to obtain a time-domain curve of the weighted average result.It is found that the weighted average result has higher clarity and stability of the time-domain curve,To further improve the accuracy of defect diagnosis in the additive manufacturing process.Using spectrum monitoring technology and visual sensing technology can achieve accurate diagnosis of defects in the additive manufacturing process.Finally,the 316 l stainless steel recycled powder experiment was carried out,real-time collection of spectral information,extraction of the radiation intensity of the plasma,and calculation of electron temperature and the ratio of the radiation intensity of the plasma.It was found that the ratio of the radiation intensity of the plasma,electron temperature and the radiation intensity of the plasma increased with the number of powder recovery increase and increase,further analysis of the structure and mechanical properties of the recycled powder additive,the central region of the original powder additive is columnar crystals,and the central organization of the recycled powder additive is equiaxed crystals,and the mechanics of powder recovery at one time the performance is better,the recycled powder can be used again.