Development And Research Of Detection System For Metal Surface Defect Repair Device

Metal parts will inevitably produce cracks and other defects during production and processing.During the production process,common cracks on the metal surface include casting cracks,forging cracks and heat treatment cracks.In the course of use,due to the long-term effect of uneven loads such as external alternating stress,fatigue cracks will occur on the surface of the workpieces.If these workpieces with crack defects continue to be used,micro-cracks on the surface will expand to form larger cracks,reduce the mechanical properties of the workpiece,affect the normal operation of mechanical equipment,severely cause the workpiece to break along the crack and cause major security incident.Aiming at the micro-crack defects generated on the metal surface,a detection system for repairing metal surface defects was developed based on LabVIEW and Arduino programming languages.The system mainly includes defect detection system,distance detection and over-range alarm system,temperature detection and powder feeding system.The system can realize the detection of the metal surface as well as the collection and storage of data during the crack repair process and has high application value.The defect detection system mainly adopts the optical system design of the coaxial optical path,and uses the industrial CCD camera to detect the defect on the surface of the workpiece to realize the positioning and detection of the crack defects on the surface of the workpiece and the storage of video information during the crack repair process.The amount of defocus is an important parameter in the process of laser repair.Ultrasonic sensor with temperature compensation is used to detect the distance from the nozzle of the laser head to the surface of the workpiece to be repaired.At the same time,the system design has the functions of distance over-range alarm,so as to realize the real-time monitoring and alarm of the distance.The powder feeding system is the core part of the laser repair technology.The stability of the powder feeding system directly determines the quality of the repair of metal surface defects.Therefore,based on the image processing technology and the principle of light scattering,a set of powder particle detection device was designed.The high-speed camera was used to capture the powder particle transportation status in the pipeline,then images was transmitted to the computer.The information such as the concentration and flow of the powder was obtained through calculation and analysis,and the output pulse of the Arduino actuator is controlled by a computer to adjust the speed of the stepper motor,that is,the amount of powder is adjusted,and finally the dynamic control of the metal powder is realized.In order to realize the powder detection efficiently and accurately,by analyzing the moving state of the powder particles in the pipeline and the mathematical calculation,it is finally determined that the transparent rubber pipeline external diameter D_out=10mm,inner diameter D_in=8mm is used as the conveying pipeline.Using air as power source,by calculating the critical velocity V_k of pipeline powder conveying during gas-solid two-phase flow,the gas conveying velocity V₃=2m/s,and the gas flow rateQ_a=6.03L/min.then,the simulation and calculation results of the powder state of pipeline transportation by Fluent software are in good agreement,and the feasibility of the powder detection device is verified.