Study On Metal Transfer Behavior Of Ultrasonic-mig Hybrid Welding

In modern industry, the metal inert gas welding is a widely used welding method, which can almost weld all metals. It has many advantages, such as high efficiency, good welding quality, and easy to realize automation. Applying ultrasonic in the welding, it becomes a new welding method, the ultrasonic-MIG hybrid welding. It plays an active role in improving welding production efficiency and welding quality. In this paper, based on previous research, the metal transfer behavior of ultrasonic-MIG welding was systematic studied and the mechanism was explored initially.The short circuiting transfer in ultrasonic-MIG welding was studied. A reasonable comparison welding parameters was designed. Based on the typical short circuiting transfer process, a whole aware of conventional MIG and ultrasonic-MIG hybrid welding was started. The characteristics of ultrasonic-MIG hybrid welding were analyzed on the transfer frequency and the interval for short circuiting transfer. The results showed that the transfer frequency was increased significantly and the interval was enlarged when ultrasonic was applied for a given wire feed speed.The transition of metal transfer was analyzed in ultrasonic-MIG hybrid welding after ultrasonic vibration applied. The stability was evaluated on transfer frequency and peak current. It showed that the ultrasonic vibration made the conventional MIG welding progress more stable and the transfer frequency higher; made the unstable conventional MIG become stable; made the free flight become short circuiting transfer. The arc shape was compared between conventional MIG and ultrasonic-MIG hybrid welding, and the curve of arc length and arc voltage was drawn. The characteristics of melting curve were analyzed. The results showed that the arc had a higher energy density and very, the thermal efficiency and arc regulatory were improved in ultrasonic-MIG hybrid welding, which made the welding progress more stable.In addition, the droplet transfer behavior was studied in ultrasonic-MIG hybrid welding. Based on the reasonable welding parameter, the typical droplet transfer was analyzed on droplet transfer frequency, the arc and droplet shape to show the characteristics. The results showed that the droplet transfer frequency was increased with the wire feed speed; the shape and volume of droplet were changed; the arc shape was different in combustion burning and detachment.The force model of droplet was established. The droplet size was calculated by static force balance for conventional MIG and ultrasonic-MIG hybrid welding, which showed that the calculated values were good agreement with measured values for conventional MIG, but deviated with ultrasonic-MIG hybrid welding. The force caused by ultrasonic was analyzed based on the difference of droplet mass. The results showed that the force caused by ultrasonic was in the same order with plasma flow, and decreased slowly with the welding current increasing. The droplet movement was analyzed to study the sound field distribution in ultrasonic-MIG arc space, which showed that the force caused by ultrasonic was not always the same in arc space, and it was different with the height from the workpiece in size and direction.