Research On Technology Of Laser Enhanced Metal Transfer Control In Underwater Hyperbaric MIG Welding

Because underwater hyperbaric welding has good welding quality and goodadaptability, it is an important structure underwater bigger space at the heart of thewelding repair technology, it was used in Marine structures, nuclear power plantreactor internals and metro shield machine cutter disc and cutter site emergency repairwork. MIG welding has the advantages of high efficiency and easy to realizeautomation, it is the main direction of underwater hyperbaric welding, but due to theeffect of the underwater environment, good melt dripping transition state is difficult torealize, so the present study and application. And high pressure dry underwaterwelding with the laser can be generated by laser molten drops when the recoil forcehelp separation of molten drops, and adjusting the parameters of the laser to obtain theideal melt dripping transition state.For the study of the intuitive melt dripping transition state, I set up a high speedcamera system. By optimizing the backlight device, reasonable light path system isdesigned and optimized by the X-ray and filter, welding droplet transition process ofthe image can be clear display and records, for the subsequent image processingprovides a reliable source of image information. Requires in order to adapt to highpressure environment, I design the high speed camera protection device, ensure thenormal welding image acquisition under the high pressure environment and the dropshot.To ensure that laser enhanced test in high pressure environment, and to ensurethat no laser welding head system under high pressure, based on the laser spot sizeand is focused on the calculation of the light path, I design the laser wear tank system,to ensure that the transition from atmospheric pressure to high pressure conditionslaser direction does not change, at the same time to ensure the high pressure tanksealing, for the purpose of the auxiliary welding under the high pressure test laid thefoundation of hardware.To verify the supporting role of laser to melt dripping transition, to establish a setof laser atmospheric environment auxiliary droplet transition test system, laserenhanced test was carried out by atmospheric environment. Trials of the short circuittransition state parameters, by using the laser assisted before and after the comparative study on the melt dripping transition state, prove that adding auxiliarylaser can cause changes in the droplet transition form, and is found by calculatingchanges of laser recoil force rather than laser radiation heat. For quantitative laser tomelt dripping transition state and the influence of the droplet size, with the drop ofmolten drops transition high-speed image in edge detection and extraction, and theextraction results analyzed, the results show that a certain power density of laser onthe improvement of the melt dripping transition state has obvious effect.Based on the above system structures, and the atmospheric pressure welding test,I took0.2MPa,0.4MPa and0.6MPa pressure under different laser power density oflaser assisted MIG test, Using high speed camera system in high pressureenvironment to drop image acquisition, to observe the change process of meltdripping transition state, and record the pressure environment to realize the transitionfrom dropwise to spray transfer when the laser power, by writing droplet size contourrecognition and calibration algorithms, and the droplet transition image processing,and will be the same pressure drop transition of different laser power image contrastanalysis, obtained the laser power, droplet size and the corresponding relationshipbetween the environmental stress size, for the purpose of high pressure closed loopcontrol of laser assisted droplet transition laid the foundation part.The innovation of this paper are the following: the first to use laser assisteddroplet transition control technology is introduced into the dry underwater weldingexperiment,60m water depth within the scope of dry welding process parameters, thelaser parameters and environmental pressures on underwater high-pressure GMAWwelding droplet transition state influence law research; For the first time to carry outthe underwater pressure drop transition laser enhancement image processingtechnology research.Project related research results to enriching the connotation of the theoreticalresearch of underwater welding, to stabilize the underwater MIG welding droplettransition state implementation and lay a foundation for its accurate closed-loopcontrol.