Gas shielded weldingIt is a welding method that uses gas shielded arc and molten pool, and is widely used in the welding of various metal materials. Gas shielded welding has the advantages of fast welding speed, high weld quality, small deformation and strong adaptability, but there are also some operational difficulties, which require welders to master the correct process parameters and operation skills in order to ensure the welding effect. This article will introduce several common difficulties in the operation of gas shielded welding technology and their countermeasures.
Welding wireIt is the main consumable material for gas shielded welding, and its quality and wire feeding method directly affect the welding quality. The selection of welding wire should be comprehensively considered according to the nature of the welded material, welding position, welding method and other factors, and generally should match the chemical composition and mechanical properties of the welded material, and at the same time pay attention to the diameter, surface quality, plating, flux core and other characteristics of the welding wire. There are two kinds of wire feeding methods: manual wire feeding and mechanical wire feeding, and mechanical wire feeding is generally used to ensure the stability and continuity of wire feeding. Pay attention to the following points when feeding the wire:
The wire feeding speed should be coordinated with the welding current, arc length, welding speed and other factors to maintain the smooth transition of the molten droplet and the stability of the molten pool. If the wire feeding speed is too fast or too slow, it will lead to poor droplet transition, resulting in defects such as spatter, porosity, undercut, etc.
The hold-down wheel of the wire feeder should match the diameter and type of the wire to ensure that the wire is firmly and smooth. The pressure of the compression wheel should be appropriate, too large will cause the welding wire to deform, too small will cause the wire to slip.
The extension length of the welding wire should be moderate, generally 10 20mm, too long or too short will affect the stability and protection effect of the arc, resulting in porosity and spatter.
The welding wire should be kept clean to avoid the pollution of impurities such as oil, rust and dust, otherwise it will reduce the conductivity and melting of the welding wire, resulting in arc instability and porosity.
Shielding gasIt is an important part of gas shielded welding, and its function is to protect the arc and the molten pool, prevent the invasion of impurities such as oxygen and nitrogen in the air, and also affect the characteristics of the arc and the transition of molten droplets. The selection of shielding gas should be comprehensively considered according to the nature of the welded material, the type of welding wire, the welding position, the welding method and other factors, generally there are pure carbon dioxide, pure argon, argon-carbon dioxide mixture, argon-oxygen mixture and so on. The flow rate of the shielding gas should be appropriate, too large or too small will affect the protection effect, resulting in porosity and splashing. Attention should be paid to the following points in the flow rate of shielding gas:
The flow rate of shielding gas should be adjusted according to the diameter of the welding wire, welding current, arc length, welding speed, welding position and other factors, generally 10 20l min, the flow rate can be smaller when welding in horizontal position, and the flow rate should be larger when vertical and vertical welding.
The flow rate of the shielding gas should be matched to the inner diameter and shape of the nozzle to ensure uniform distribution and effective coverage of the shielding gas. The inner diameter of the nozzle should be suitable for the diameter of the welding wire, too large or too small will affect the protection effect, resulting in porosity and spatter.
The flow rate of the shielding gas should be coordinated with the wind speed of the environment to avoid the shielding gas being blown away by the wind, resulting in insufficient protection, pores and splashes. In a windy environment, measures such as shielding, reducing the flow rate, and increasing the inner diameter of the nozzle should be taken to ensure the protection effect.
Welding current, voltage and welding speedThey are the main process parameters of gas shielded welding, which directly affect the characteristics of the arc, the transition of molten droplets, the formation of molten pools and the forming of welds. The selection of welding current, voltage and welding speed should be comprehensively considered according to the thickness of the welded material, the diameter of the welding wire, the welding position, the welding method and other factors, and the matching of current, voltage and welding speed should be maintained, so that the temperature, pressure, flow, surface tension and other aspects of the molten pool should be balanced to avoid porosity and spatter. The welding current, voltage and welding speed should pay attention to the following points:
The welding current should be matched with the thickness of the welded material, the diameter of the welding wire, the welding position and other factors, generally 50 500A, too large or too small will affect the depth and width of the molten pool, resulting in porosity and spatter.
The welding voltage should be matched with the welding current, the extension length of the welding wire, the welding position and other factors, generally 15 35V, too high or too low will affect the length and stability of the arc, resulting in porosity and spatter.
The welding speed should be matched with the welding current, voltage, diameter of the welding wire, welding position and other factors, generally 10 40cm min, too fast or too slow will affect the depth and width of the weld, resulting in porosity and spatter.
The angle and oscillation of the welding torch are important operating techniques for gas shielded welding, as they affect the direction of the arc, the shape of the weld pool, the distribution of shielding gases, and the formation of the weld. The angle and swing of the welding torch should be flexibly mastered according to the thickness of the welded material, the diameter of the welding wire, the welding position, the welding method and other factors, and the stability and continuity of the welding torch should be maintained
The angle of the welding torch should be matched with the welding direction, welding position, welding method and other factors, generally 60 80°, too large or too small will affect the alignment and protection effect of the arc, resulting in porosity and spatter.
The swing of the welding torch should be matched with the welding current, voltage, diameter of the welding wire, welding position and other factors, generally 5 10mm, too large or too small will affect the uniformity and beauty of the weld, resulting in porosity and spatter.
There are several swing modes of welding torch, such as straight line swing, triangle swing, arc swing, etc., and the appropriate swing mode should be selected according to the shape and requirements of the weld to ensure the filling and fusion of the weld.
In short, there are many difficulties in the operation of gas shielded welding technology, and welders need to select appropriate process parameters and operation skills according to specific welding conditions and requirements in order to ensure welding quality and efficiency. The operation of gas shielded welding technology is also a combination of technology and art, which requires welders to continuously learn and practice to improve their skills and level.