Structural Design On Air Curtain Rotating Arc Sensor And Its Welding Arc Characteristic Research

With the marine development, the nuclear power industry development and a lot of port project construction, underwater welding technology plays a very important role in these aspects, arid improve and develop and need to great improvement and development. Local dry underwater welding has the high quality welding seam of dry underwater welding and easy and simple technology of wet underwater welding. the local dry underwater welding Based on rotating arc sensor is to benefit of raising the level of underwater welding automation,the welding technology is worth researching.Thesis aims to the purpose of improve the underwater welding quality and improve the underwater welding automatic tracking, combining with part of the structure of laboratory existing rotating arc sensor, and developed a kind of air curtain rotating arc sensor applied in underwater local dry welding of to improving underwater welding quality. The sensor's working principle is to use high-pressure air through drainage device to drain off the watet of welding areas, so as to achieve the purpose of local dry welding. The sensor combined drainage device and sensor with an organic whole, and integrated high-pressure air pipe and protection gas pipeline into arc sensor; The drainage device adopted the contraction nozzle to speed up air currents, thus reach drainage purposes. Aims to the designed drainage device, the gas-liquid two phase flow numerical simulation of flow field has been done. Through the analysis of pressure field, velocity field and velocity vector field, verified the feasibility of the drainage device designing.With established air curtain rotating arc sensor of underwater welding arc argon plasma numerical simulation model, study changing trend of welding arc characteristic in the local high-pressure gas cover. Under the optimal welding parameters in the air(current 260A, voltage 24V), under the conditions of argon as the protection of the gas, arc length 12mm, straight polarity direct current, respectively in environmental pressure 0.1 MPa,0.4 MPa and 0.6 MPa,with the help of numerical simulation, plasma temperature, current density has been researched.The simulation results show that, with the environmental pressure increasing, arc temperature has dropped and arc current density has increased somewhat, arc has a shrinking trend, arc diameter decreased, arc became unstable and present short-circuit transition phenomenon. Appropriate elevated arc voltage can effectively solve the problem the arc length is compressed. when make the orthogonal test with air curtain rotating arc underwater welding, we can roughly predict the level value of current and voltage factor in orthogonal test by the arc simulation.Established the underwater welding hardware platform and software system. With six influencing factors for air curtain rotating arc sensor underwater local dry welding, the orthogonal experiment table was designed. By the test,the optimum process parameters of local dry welding is obtained. Through comparing the land welding effect and underwater wet welding effect and the contrastive analysis of X-ray detection of welding seam and the contrastive analysis weld section, we can get that local dry welding seam quality relative to wet welding has greatly improved.