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Downward automatic welding method of gas-shielded alkaline flux-cored wire for long-distance pipeline

A welding method and technology of flux-cored welding wire, applied in welding medium, welding equipment, welding equipment and other directions, can solve the problems of insufficient refinement of metal grain structure, thick single welding seam thickness, and reduction of post-heating times, etc. Achieve the effects of excellent mechanical properties, high impact performance of welds, and reduction of welding heat input

Active Publication Date: 2020-02-11
吴立斌 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In the prior art, the upward welding method is adopted for fully automatic welding. When the welding wire melts and enters the pipeline weld seam, it needs to overcome the influence of gravity, so the solidified weld metal below needs to have a certain thickness for support. Therefore, when the upward welding method is adopted, the thickness of a single weld seam It is thicker, resulting in a reduction in the total number of welding layers, and further, reducing the number of post-heating of the last weld to the previous weld, and the grain structure of the metal is not fully refined, which reduces the toughness of the weld
If the original upward welding process is directly changed to downward welding, it will lead to uneven flow of molten pool and poor weld formation, especially the problem that the center of the welding seam is raised in the downward welding position

Method used

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  • Downward automatic welding method of gas-shielded alkaline flux-cored wire for long-distance pipeline
  • Downward automatic welding method of gas-shielded alkaline flux-cored wire for long-distance pipeline
  • Downward automatic welding method of gas-shielded alkaline flux-cored wire for long-distance pipeline

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] Nozzle group pair: the nozzle group pair uses an inner mouthpiece (such as figure 1 ), the blunt edge of the groove is 1.5mm, and the pairing gap is 1.0mm. Groove processing uses an internal expansion beveling machine for pipe mouth processing.

[0040] The downward automatic welding is preferably carried out with a single torch external welding machine. The single torch external welding machine has flat external characteristics and the drop rate of the current and voltage curves is not more than 5%. The welding cable is 50 square millimeters and the length is 25 meters. .

[0041] Filling and capping welding material: basic gas shielded flux cored wire, Φ1.2mm, basic flux cored wire includes the following components in mass fraction: CaF 2 25%, CaO 40%, SiO 2 20% and TiO 2 10%, Potassium Carbonate 2%, Sodium Carbonate 3%, the average value of welding wire deposited metal is 3.3mL / 100g measured by mercury method and chromatography; pure CO 2 The flow rate is 30L / mi...

Embodiment 2

[0049] Nozzle group pair: the nozzle group pair uses external mouthpieces (such as figure 2 ), the blunt edge of the groove is 2mm, and the pair gap is 2mm. Groove processing uses an internal expansion beveling machine for pipe mouth processing.

[0050] The downward automatic welding is preferably carried out with a single torch external welding machine. The single torch external welding machine has flat external characteristics and the drop rate of the current and voltage curves is not greater than 5%. The welding cable is 75 square millimeters and the length is 35 meters. .

[0051] Filling and capping welding material: basic gas shielded flux cored wire, Φ1.2mm, basic flux cored wire includes the following components in mass fraction: CaF 2 25%, CaO 30%, SiO 2 20% and TiO 2 20%, potassium carbonate 3%, sodium carbonate 2%, the average value of welding wire deposited metal is 3.2mL / 100g measured by mercury method and chromatography; pure CO 2 The flow rate is 21L / min....

Embodiment 3

[0058] Nozzle group pair: the connecting pipe material has a pipe weld (such as image 3 ), grind the weld until the base metal is flush, and the grinding length is 100mm, and the right and wrong sides are 10% of the wall thickness and evenly distributed along the perimeter. Groove processing uses an internal expansion beveling machine for pipe mouth processing.

[0059] The downward automatic welding is preferably carried out with a single torch external welding machine. The single torch external welding machine has flat external characteristics and the drop rate of the current and voltage curves is not greater than 5%. The welding cable is 50 square millimeters and the length is 20 meters. .

[0060] Filling and capping welding material: basic gas shielded flux cored wire, Φ1.2mm, basic flux cored wire includes the following components in mass fraction: CaF 2 35%, CaO 25%, SiO 2 25% and TiO 2 10%, potassium carbonate 1%, sodium carbonate 4%, the average value of welding ...

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Abstract

The invention provides a downward automatic welding method of gas-shielded alkaline flux-cored wire for a long-distance pipeline, and belongs to the field of welding. When the alkaline flux-cored wireis used for downward welding, the welding polarity is straight polarity direct current; pure CO2 is used as shielding gas, so that the arc blowing force and the depth of fusion during welding are ensured, the molten pool flowing is uniform, and the weld formation is good; especially the weld at the over-head position of welding is not prone to bulge, so that the welding arc has sufficient blowingforce to spread the molten pool evenly to the two sides of a groove; the surface of the entire circumferential weld is flat and slightly concave; the cleaning after welding is easy; incomplete fusiondefects are difficult to occur; and the percent of pass of welding is increased.

Description

technical field [0001] The invention relates to the field of welding technology, in particular to a downward automatic welding method for gas-shielded basic flux-cored welding wire for long-distance pipelines. Background technique [0002] In the construction of long-distance pipelines, the main components of welding wire powder used in flux-cored wire gas-shielded automatic arc welding are acidic oxides, such as rutile, etc., and the automatic welding wire feeding system and welding head are used to control the welding arc and welding wire feeding. The welding direction is upward welding, and the shielding gas is a mixture of argon and carbon dioxide. The main purpose of using acid welding wire is to ensure the operability during welding. This process is mainly used for filling and cover welding of weld seams. DC reverse. Similar to this, another semi-automatic flux-cored self-shielding welding process in the construction of long-distance pipelines uses flux-cored wires wh...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K9/16B23K9/028B23K35/36B23P15/00
CPCB23K9/0282B23K9/16B23K35/0266B23K35/3605B23P15/00B23K2101/06
Inventor 吴立斌陈劲张圆李阳
Owner 吴立斌
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