| Arc additive manufacturing(AM),as a new type of component forming method,has higher forming efficiency than laser additive manufacturing.Compared with casting and forging forming methods,it does not require molds and can form large metal components with complex structures.It is widely used in the manufacture of personalized products such as aerospace,aviation,and large-scale metal structural parts of ships.The high-performance large metal components formed by arc additive manufacturing should not only have good structure and mechanical properties,but also their forming dimensions and shapes must strictly meet the requirements.To this end,a laser arc composite additive manufacturing system was built,the law of laser action on the arc was studied,the mathematical model of the process parameters and the maximum arc diameter was established,and the multi-layer multilayer metal size prediction model was established based on the size of the molten pool.The monitoring of the size of the formed component in the arc additive manufacturing process is introduced.The laser arc composite additive manufacturing system built includes two parts:hardware and software.The hardware part of the laser arc composite additive manufacturing system is composed of arc additive equipment,laser equipment,and vision equipment.The software part is composed of laser unit,vision unit,data storage and review unit.The software is used to initialize the hardware and control the working status of the hardware.At the same time,it collects and saves data such as laser power,arc image,molten pool image,component height and width during the forming process.The arc image processing method is designed to extract the maximum arc diameter through noise removal,contrast enhancement,global threshold segmentation,contour extraction,calculation of arc contour in the world coordinate system,arc contour line fitting and reconstruction,etc.,and the maximum arc diameter obtained by arc image processing The relative error does not exceed 5.97%.When there is no laser arc recombination,the maximum arc diameter is approximately linearly positively correlated with the current;when the laser arc recombination,when the current is less than 210A,the maximum arc diameter is negatively correlated with the laser power and positively correlated with the laser spot size;when the current exceeds 210A,it is correlated with the laser The correlation between power and laser spot size is small.Through the quadratic regression universal rotation combination test,a mathematical model between the maximum arc diameter and the arc current,laser power,and laser spot size is established,which is D=3.7567+0.024 I-8.889×10-4P-7.767×10-3L-8.849×10-7IP+7.836×10-5PL,this model arc The prediction error of the largest diameter is less than 6.03%.According to the characteristics of the molten pool image,a method for extracting the size of the molten pool is designed,including camera calibration,molten pool image screening,noise removal,adaptive threshold segmentation,contour extraction,contour completion,contour coordinates and inclination calculation,etc.The distance between the extracted solid-liquid boundary point at the end of the molten pool and the previous accumulation layer was used as the height of the stacked metal,and the maximum width of the molten pool was used as the width of the stacked metal,thereby establishing a single-channel single-layer stacked metal size prediction model,and the prediction error was less than 7.8%;The semi-ellipse model,arc model,cosine model,and parabola model are used to fit the single-channel single-layer stacked metal section contour lines.Among them,the parabolic model has the smallest fitting variance,and the mean square error is 3.14.Calculate the cross-sectional area of single-pass single-layer stacked metal based on the parabolic model,and calculate the height of multiple single-layer stacked metal using the isometric method;add the width of each stacked metal and subtract the overlap amount to obtain the width of multiple single-layer stacked metal.As a result,a prediction model for the height and width of multi-channel single-layer stacking and multi-channel multi-layer stacking is established.The heights are (?),width is (?),the prediction error is less than 5.5%.Laser arc composite additive manufacturing rocket motor conical shell.Based on the height value of the component,the non-uniform-thickness layered slices are performed,and the inside of each slice is filled from the outer contour to the inner contour according to the offset.According to the different characteristics of the wall thickness of different parts of the component,the width of each metal deposited in each part of the slice is designed,and the mathematical model between the maximum arc diameter and the process parameters established is used to determine the process parameters when the different parts of the component are stacked.The height error value of the final formed component is 3.1mm,the wall thickness error value is 6.7mm,and the cone angle error value is 2.4°.The cone-shaped component of the laser arc composite additive forming meets the size and shape requirements. |
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