1. Advantages
1) High welding productivity: due to the high welding current density, high arc heat utilization rate, and no need to clean slag after welding, the welding productivity is greatly improved. Compared with ordinary electrode arc welding, the welding efficiency is increased by 2~4 times.
2) Low welding cost: CO2 gas has a wide source, low price, and low power consumption. The welding cost is only 40%~50% of submerged arc welding or arc welding (and compared with electrode arc welding, there is no welding material. waste, more economical and environmentally friendly).
3) Small welding deformation: Due to the concentrated arc heating, the heating area of the weldment is small, and the CO2 airflow has strong cooling properties, so the welding deformation is small, and it can also be used for thin plate welding.
4) High welding quality: less sensitivity to rust, less hydrogen content in the weld, and good crack resistance.
5) Wide range of applications: all-round welding can be achieved (1G, 2G, 3G, 4G, 5G, 5GR, 6G, 6GR and other types of welding can be realized, and are widely used in flat plate, tank and pipeline welding) , and can be welded for thin, medium and even thick pipes (all-round automatic welding can be realized whether it is a wide gap weld or a narrow gap weld).
6) Simple operation: no slag cleaning is required after welding, and the welding seam is obvious, which is convenient for monitoring, which is conducive to the realization of mechanized and automatic welding (taking Tianjin Yixin all-position pipeline automatic welding equipment as an example, this equipment can realize all-position automatic welding of pipelines , and added parameter preset and programming functions, basic welders can quickly get started and ensure the quality of welds).
2. Process parameters
For CO2 gas shielded welding, there are mainly three forms of droplet transfer, namely short-circuit transfer, droplet transfer, and jet transfer. In the following, the welding process parameters of CO2 gas shielded welding are introduced by taking the short-circuit transition as an example.
Short-circuit transitions occur with thin wire, low voltage, and low current. During short-circuit transition welding, the main welding process parameters are arc voltage, welding current, welding speed, gas flow and purity, and wire extension length.
1) Arc voltage and welding current
Arc voltage is a key parameter during short-circuit transition, which is characterized by the use of low voltage. Appropriate arc voltage and good welding current are matched, and a stable welding process with small spatter and good weld formation can be obtained.
2) Welding speed
With the increase of welding speed, the weld width and penetration depth decrease. If the welding speed is too high, it is easy to produce defects such as undercut and incomplete penetration. If the welding speed is too low, defects such as burn-through and coarse structure are easy to occur, and the deformation increases and the production efficiency decreases. Therefore, the correct choice of welding speed should be made according to production practice.
3) Gas flow and purity
When the gas flow rate is too small, the purity of the shielding gas is insufficient, and defects such as pores are easily formed in the weld; Seam quality is degraded. When the welding current is large or the welding speed is too fast, the length of the welding wire is long, and when welding on site, the gas flow should be increased to ensure the welding quality.
4) Wire extension length
Since the short-circuit transition uses thin welding wire, the extension length of the welding wire has a great influence on the resistance heat. The extension length of the welding wire becomes longer, the resistance heat on the welding wire increases, the melting of the welding wire is accelerated, and the productivity is improved. However, if the extension length is too long, the welding wire is likely to overheat and melt away in sections, resulting in serious splashing. According to the survey, the extension length of the welding wire increases from 20mm to 30mm, the amount of spatter increases by about 5%, the welding process is unstable, and the distance between the nozzle and the weldment increases after the extension length increases, so the gas protection effect becomes worse . If the extension of the welding wire is too short, the distance between the nozzle and the weldment will be shortened, and the splash metal will easily block the nozzle. The proper wire extension should be 10 to 12 times the wire diameter.
The specific process parameters related to welding equipment should be subject to the actual application on site. If you have any questions, please contact our company directly. (Tianjin Yixin has been focusing on the production, research and development and sales of automatic pipeline welding equipment for more than ten years. Its self-developed pipeline full-position automatic welding machine (also known as pipeline intelligent welding machine, orbital welding machine, orbital welding equipment, Automatic welding equipment, on-site pipeline automatic welding equipment, pipeline automatic welding machine, etc.) are widely used in the welding of pipelines, plates, tanks, etc. in various industries, with high welding efficiency and beautiful shape, which is an excellent choice for pipeline welding)
Post time: Sep-07-2022