Experimental Research On Laser Cladding Molten Pool Detection And Process

Laser cladding technology is a new type of special processing technology which is belonged to surface additive manufacturing.Due to its excellent surface repair modified advantages,it is a major boost of the green environmental protection circular economy.It has attracted people's attention and has been widely applied in the defense industry and social production,there are mainly additive manufacturing,laser repair,surface modification and so on.In recent years,with the development of software and hardware of high-power and high-precision laser equipment,the huge industrial demand and the processing on special occasions,laser cladding technology has been more widely used.However,laser cladding technology has poor repeatability,low precision,unstable processing quality and lack of effective detection means in actual processing and production,so the automation level needs to be improved.Aiming at the above problems,this article takes the improvement of the dimensional accuracy and stability of the molten pool as the starting point,and adopts machine vision method to detect the shape of the molten pool,and studies the variation rules between the process parameters with the characteristic parameters of the molten pool and the quality of the cladding layer,and lays a solid foundation for the closed-loop control system for online detection of molten pool signals.This article mainly includes the following aspects:(1)Taking the laser molten pool as the measurement objection,design and build a molten pool detection device,under the condition of not interfering with the laser cladding process,install the color CMOS camera fixed on the bracket laterally to the machine arm where the laser head is located.The pool image is processed digitally,and the OpenCV vision library is used for programming,through which the characteristic parameters of the molten pool are extracted,and finally store the data.The characteristic parameters of the molten pool mainly include the length,width and area parameters of the molten pool.(2)Study the variation rules of the synchronous powder feeding laser cladding molten pool and cladding layer's quality with process parameters as well as the relationship between the two.The single factor method is used to cladding Ni60 alloy powder on the 45 steel substrate.The control parameters are scanning speed,laser power and powder feeding rate,and the extraction targets are length,width and area of the molten pool in the actual cladding process.Prepare metallographic samples for analysis and evaluate the quality of the cladding layer.The quality of the cladding layer includes the interface bonding,the width and height of the cladding layer,the depth of the heat-affected zone and the dilution rate parameters.(3)The orthogonal method is used to conduct experiments to optimize the cladding process parameters.The optimization result shows that the cladding quality is the best when the powder feeding rate is 10g/min,the scanning speed is 400mm/min,and the power is 900W.The height of the cladding layer is 1352.24?m,the depth of the molten pool is 141.05?m,and the obtained dilution rate is 9.45%,which fully proves the validity of the optimized results.In this paper,a pool detection device based on image processing technology is established to complete the single factor and orthogonal experiments of laser cladding with synchronous powder feeding.The influence rules of process parameters on the pool characteristic parameters and the quality of cladding layer are obtained,and the optimal process combination parameters of cladding quality are mastered.