(3) Gas flow

L = (10 - 12) d L / min too large: turbulent flow, causing air intrusion, resulting in pores. Too small: gas protection is not good. The wind speed is not affected when it is ≤ 2m / s. Measures should be taken when the wind speed is ≥ 2m/s.

1 Increase the gas flow rate. 2 Take measures to block the wind.

Note: When a gas leak occurs, the weld will have pores, and the leak point must be treated. It cannot be supplemented by increasing the flow rate.

(4) Arc force

When different thicknesses, different positions, different specifications, different welding wires, choose different arc forces. Too big: the arc is hard and the splash is large. Too small: the arc is soft and the splash is small.

(5) Pressing force

Too tight: the wire is deformed and the wire feed is unstable. Too loose: the wire slips and the wire feed is slow.

(6) Power polarity

DC reverse polarity: large penetration depth, small splash, stable arc formation, and low hydrogen content in the weld. DC positive polarity: Under the same conditions, the wire melts quickly. It is 1.6 times the reverse polarity, the depth of penetration is shallow, the height is high, and the splash is large. Used in surfacing, cast iron repair, and high speed welding.

(7) Welding speed

The welding speed has an important influence on the quality of the inside and the appearance of the weld. When the current and voltage are constant: the welding speed is too fast: the penetration depth, the melting width, the residual height is reduced, the convex or hump weld bead, the weld toe bite . When the welding speed is too fast, the gas protection effect is destroyed and the pores are easily generated. At the same time, the cooling rate of the welding chamber will be accelerated accordingly, thus reducing the plasticity and toughness of the welding metal. And it will cause an edge in the middle of the welding, resulting in poor molding. The welding speed is too slow: the molten pool becomes larger, the weld bead becomes wider, and the weld toe is overflowing. The welding speed is slow and the gas in the molten pool is easily discharged. The weld metal structure is coarse or burnt due to overheating.

The welding parameters should be selected according to the following conditions: the weld appearance is beautiful, and there are no defects such as burn through, undercut, pores and cracks. The penetration control is within the proper range. The welding process is stable and the splash is small. I heard the sound of sand...sand when welding. At the same time, it should have the highest productivity. The welding specifications for CO2 welding mainly include: welding current, arc voltage, welding speed and gas flow. These parameters have a great influence on the heating and melting of the wire and the formation of the weld.