Realization Of Ultra-narrow Gap Welding With Flux Strips Constraining Arc

Ultra-narrow gap welding is widely regarded as an important technology because of its advantages such as high productivity and lower welding distortion. The key technology of ultra-narrow gap welding is the problem of the sidewalls fusion, many scientists invent many ways to solve this problem such as arc oscillation and arc circumrotation. But the complexity of these methods constrained the practicality of these methods applied in industry productivity. The thesis searched a new way to realize the ultra-narrow gap welding by using the gap of 5 mm, the flux strips that made of special aggregates are put into arc zone through the gap sidewalls. Flux strips can constrain arc to prevent it from going upside, and control the heating zone effectively to ensure good fusion of the sidewalls.We designed a new welding torch for ultra-narrow welding with flux strips constraining arc. The tip is the spring structure with double copper plates. To ensure reliable conductivity and endurance of the tip, equations describing the deformation and force of the tip were set to designed geometry of the copper plates accurately. The results of experiment show that we could get good welding joint with the ultra-narrow welding torch.We may get welding flaws because of the inappropriate gas shielding during the welding, so we decided to put argon gas into the gap to protect the welding area. We should find out the accurate size of the gas vessel and proper gas flow. If we take the improper size and gas flow, we may get welding flaws because of the turbulent flow. So we put the argon gas through the copper gauze heated by electric current, and we continue putting the gas when the copper gauze cooled. After that we could get very clear protected region. So the relationship between protected region and the size of the gas vessel and proper gas flow is summarized as fellows: length of vessel section is 15 mm , and the width is 2.5 mm, and gas flow is 10 L/min. With these parameters, we could get the efficient protected region and the proper variable protecting distance. And the results of experiment show that we could get good welding joint with appropriate quantity of inert gas flow. For this reason we should find the very proper maximum and minimum of the quantity of inert gas flow during the welding by using the brass wires oxidation experiment.