Argon tungsten arc welding
Tungsten argon arc welding is one of the main method of welding of aluminum and its alloys is one of the most common, this kind of welding power source adopts the ac power, it has high thermal efficiency and tungsten bearing capacity, and can use "cathode crushing effect" clear the oxide film on the aluminum plate welding parts surface, to run the welding, and get a bright and beautiful of the surface of the weld.
During the welding process, the position of welding gun, welding wire and workpiece should be maintained, as shown, the general Angle of the three. Due to the size of the workpiece, joint form, welding parameters, welder's technology and so on, the Angle between the torch and the workpiece is slightly different during the whole welding process. Manual argon tungsten arc welding generally adopts the left welding method, welding torch should be uniform and smooth forward for straight line, and maintain a constant arc length, in the butt welding without wire, arc length is about 0.5 ~ 2.0mm;The arc length is about 4 ~ 7mm in the butt welding of wire. When the welding torch moves, it can stop intermittently. When it reaches a certain depth of penetration, it starts to add wire and then moves forward.
Add wire welding, welding wire and welding torch, of good coordination when welding groove surface has yet to reach before the melting temperature, welding wire ends in arc zone and protective layer, molten pool heated to a certain temperature, the flow of molten metal has good, immediately from molten pool edge into wire, welding wire and artifacts about 10 ~ 15 ° Angle. At this point, the melted wire drops will enter the pool, so that the welding wire is added to the pool repeatedly and intermittently, so that the pool solidifies and forms a weld.
For the thick plate cover layer welding, welding gun can be slightly transverse swing, to obtain a wider weld formation, and to ensure good fusion on both sides of the weld. If a large gap is found in the assembled joint, the welding wire should be added to the weld pool quickly, and then the welding gun should be moved. At the end of welding, attention should be paid to the welding quality of the arc extinguishing, usually using the lead plate. If the arc blowout plate is not available, the welding speed and death speed can be accelerated when the arc is approaching the arc pit, and the arc blowout can be realized by gradually elongating the arc after the arc pit is filled, so as to fully protect the weld metal at the arc blowout. The main welding parameters of manual argon tungsten arc welding are:
Welding current, it mainly according to the workpiece thickness, size, joint form, welding technology and other conditions to choose. The current is too large to easily cause the workpiece burn through; Too small current will cause defects such as poor fusion of weld edge and incomplete welding.
Welding speed, which is mainly determined by welding current and preheating temperature, considering production efficiency, try to speed up the welding speed. However, too fast speed is easy to cause poor fusion at the weld edge, incomplete penetration at the root, argon laminar flow deviating from the extreme tungsten molten pool, and the molten pool has empty defects due to poor protection. The welding speed at the beginning of the joint should be smaller to ensure that the matrix metal is fully welded.
Argon flow mainly depends on welding current, welding speed, nozzle aperture and other factors. Appropriate increase of argon flow rate is helpful to resist the interference of flowing air. Excess argon flow rate will waste argon and cause irregular flow of gas protective layer, so that air will be involved. On the contrary, the protective performance and arc stability will be reduced, and even affect the forming of welding seam. In the wild or by the wind is to do a good job of preventive measures.
Nozzle aperture, manual argon tungsten arc welding nozzle aperture is about 7 ~ 22mm, with the increase of aperture, the protection zone will also expand. However, some special positions should be taken into account so as not to affect the welder's line of sight.
The position of the welding nozzle and the workpiece, the distance between the end of the welding nozzle and the workpiece is generally 8 ~ 14mm.The greater the distance, the worse the effect of dental protection; But the distance should not be too close, otherwise the tungsten is very easy to touch the molten pool and cause tungsten clamping, and destroy the stability of the arc and produce slag defects.
After welding, appearance inspection, X-ray inspection, ultrasonic inspection and so on are generally required.
