Paste The Cover Flux-chip Ultra-narrow Gap Welding

The ultra-narrow-gap welding is a high efficient welding technology whose gap is shape I and is widely concerned by many nations. The technical key of the ultra-narrow-gap welding is that gap always gets bad fusion. Many experts from different nations have invented many kinds of methods, such as arc oscillating and arc rotating, but these methods made control of the welding process and equipment more complex. Thus, the application of the ultra-narrow-gap welding is limited in many fields. The paper is researching the ultra-narrow-gap welding whose width of gap is reduced to 5mm or less to make sure that the gap is fused. The self-regulating boned flux is stuck on the gap , which can prevent welding welding arc burning up along the gap and ensure arc stabilization. The ultra-narrow-gap welding ,which weld one time on one layer without arc scillating is realized. The paper studied the new technology and explored principle by process experiment.First of all, we studied the influences of the width of gap, thickness and the component of boned flux through experiment. We found that the most appropriate width of the gap is 3.5mm, and the thickness of boned flux is 0.5mm in the ultra-narrow-gap welding. The component of flux is very important to the ultra-narrow-gap welding process with the boned flux on groove adopted. We adopted eight kinds of prescription to experiment in the paper and draw a conclusion that the prescription whose primary component is marble and fluorite is more appropriate to the ultra-narrow-gap welding. We have carried out many demonstration experiment to show that the molding of welding line is better when the boned flux has high molten point, the ingredient of slag is small and the freezing point is lower.Using the boned flux with marble and fluorite as primary component, we have studied the influences of the welding process parameters on the welding line and weld defect by many experiments. We discover that appropriate welding voltage is 21~24V,and appropriate welding current is 210-270A in the ultra-narrow-gap welding. When welding voltage is between 21V and 24V and welding current is between 210A and 270A, better welding line can be obtained. At the same time, welding defect can be avoided when welding voltage , welding current and welding velocity are better matched. If this relationship of matching cannot be satisfied well, the welding arc will burn up along the gap and molten steel is likely to overflow, resulting that the slay is larded in welding line. More research show that if welding voltage is increased, the influence of arc on groove of gap will increase. If welding current is increased, the molten highness will increase, and if welding velocity is decreased, molten width and molten highness will both increase.