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The method of demagnetization before narrow gap pulse fusion welding of oil drill collar

A narrow gap, oil drilling technology, applied in welding equipment, magnetic objects, arc welding equipment, etc., can solve problems such as poor practicability, achieve stable arc state, reduce residual magnetic field strength, and improve weld bead formation.

Inactive Publication Date: 2017-12-01
NORTHWESTERN POLYTECHNICAL UNIV +1
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Problems solved by technology

[0007] In order to overcome the shortcomings of poor practicability of the existing narrow-gap welding groove demagnetization method, the present invention provides a method for demagnetizing oil drill collars before narrow-gap pulse fusion welding

Method used

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  • The method of demagnetization before narrow gap pulse fusion welding of oil drill collar
  • The method of demagnetization before narrow gap pulse fusion welding of oil drill collar
  • The method of demagnetization before narrow gap pulse fusion welding of oil drill collar

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Embodiment Construction

[0019] refer to Figure 1-2 . Aiming at the influence of the residual magnetic intensity in the narrow gap groove on the bottom arc, the magnetic deflection blow test of the arc is specially studied. Before welding, the CT3 Teslameter was used to detect the magnetic flux density in the groove, and then the arc was ignited to weld the bottom bead. It will be unstable, and this instability cannot be overcome by adjusting the welding specification parameter value, so the weldment groove must be demagnetized before welding.

[0020] Table 1 Influence of magnetic flux density in the narrow gap groove on the arc of the bottom weld bead

[0021]

[0022] The principle of magnetic shielding is used to demagnetize the narrow gap groove of oil drill collars to avoid arc magnetic deflection during bottom arc welding. Its characteristics include the following steps:

[0023] 1. In the gun body of the existing narrow-gap pulse melting polar gas shielded automatic welding torch, a mag...

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Abstract

The invention discloses a pre-weld demagnetization method for narrow gap pulse fusion welding of a petroleum drill collar, and aims at solving the technical problem of poor practicability of an existing narrow gap welding groove demagnetization method. According to the technical scheme, a magnetic shielding ring sleeves the outside of a gun body of an existing narrow gap pulse melting arc gas-shielded automatic welding gun; the magnetic shielding ring provides unobstructed flux branch circuits for magnetic lines in grooves; and one considerable part of magnetic lines distributed in the grooves enter a drill collar weldment through the magnetic shielding ring, so that the residual magnetic field intensity of an arc space in each narrow gap groove of the drill collar weldment is obviously reduced. When the residual magnetic field intensity in each groove is measured below 4mT before being welded, the effect of arc magnetic blowing on the quality of bottom-layer welding lines of the drill collar weldment is eliminated; the arc state is stable; and the weld bead formability is good; and when the residual magnetic field intensity is measured over 4mT before being welded, the non-weldable condition is judged and loss of working time and material waste are avoided. An experiment proves that the magnetic shielding effect of the method on the grooves is obvious, the weldable rate is effectively improved, and the practicability is high.

Description

technical field [0001] The invention relates to a method for demagnetizing a narrow-gap welding groove, in particular to a method for demagnetizing an oil drill collar before narrow-gap pulse fusion welding. Background technique [0002] Document 1 "Chinese Invention Patent whose Authorized Notice No. is CN101323041B" discloses a narrow-gap pulse melting extreme gas shielded automatic welding method for petroleum kelly. This method adopts narrow-gap pulse melting electrode gas-shielded automatic welding. When welding small-diameter thick-walled oil drill collars, due to ① the residual magnetism of the weldment itself, the magnetization of the groove processing process and the narrow gap groove, the residual magnetism is in the The magnetic induction intensity in the groove increases significantly; ②During the welding process of the bottom weld, when the temperature of the weld area rises above 723°C (Curie point), the magnetic resistance of the weld and heat-affected zone in...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01F13/00B23K9/235
CPCB23K9/235H01F13/006
Inventor 马彩霞巴鲁军张铁军汪清林郑旭升王军杨思乾
Owner NORTHWESTERN POLYTECHNICAL UNIV
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