CN108856990B

CN108856990B - Method for welding inclined pipe by MAG welding

Info

Publication number: CN108856990B
Application number: CN201810792195.6A
Authority: CN
Inventors: 梁恩荣; 王跃峰; 何耀飞; 鲁晓欣
Original assignee: Pangang Group Engineering Technology Co Ltd
Current assignee: Pangang Group Engineering Technology Co Ltd
Priority date: 2018-07-18
Filing date: 2018-07-18
Publication date: 2020-11-10
Anticipated expiration: 2038-07-18
Also published as: CN108856990A

Abstract

The invention discloses a method for welding an inclined pipe by MAG welding, relates to the technical field of welding, and provides a welding method capable of improving the welding quality. The welding method comprises the following steps: A. preparing for welding; B. welding a backing weld, specifically: firstly welding an initial bottoming solidification molten pool by a three-point connection method, and then welding a plurality of bottoming solidification molten pools on two sides of the initial bottoming solidification molten pool along the axial direction of the pipe until the welding is completed for a circle; C. and (4) welding a cover surface welding line, specifically, welding a plurality of cover surface solidification melting pools along the axial direction of the pipe until the cover surface solidification melting pools are completely welded for one circle. The invention converts the continuous welding in the circumferential direction into a plurality of arc-breaking welding in the linear direction, is beneficial to controlling the angle of the welding gun during welding and is easy to ensure the quality and the shape of the welding seam.

Description

Method for welding inclined pipe by MAG welding

Technical Field

The invention relates to the technical field of welding, in particular to a method for welding an inclined pipe by MAG welding.

Background

MAG welding refers to gas metal arc welding, and compared with the existing common manual shielded metal arc welding, MAG welding has the advantages of high welding efficiency and low cost, so that the MAG welding is more and more widely applied.

The MAG welding is performed by adopting continuous arc welding when the welding component is a component with larger base material thickness such as a blast furnace shell, a converter shell and the like, or the welding seam is a flat welding seam and a flat fillet welding seam, so that the operation difficulty is smaller. However, when the butt welding of pipelines and the welding of tube plates with small thickness are carried out, the welding seam is in the circumferential direction, if the conventional continuous arc welding is adopted, the MAG welding belongs to automatic wire feeding, the wire feeding speed is high, an operator needs to control the forming of the welding seam and must ensure that the welding gun is rotated rapidly to form an angle during the welding, and the operation difficulty is high; especially, the welding difficulty is higher when the pipeline or the tube plate is in an inclined state; the problems of welding beading, improper joint treatment, undercut, deviation of welding meat, unqualified appearance and the like easily occur. Especially, the forming of the front and the back of the welding line can not be ensured at all during backing welding, and the front of the welding line is provided with deep clamping grooves formed on two sides of a middle bulge.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: a method for performing inclined pipe welding by using MAG welding capable of improving welding quality is provided.

The technical scheme adopted for solving the problems is as follows: the method for welding the inclined pipe by using the MAG welding comprises the following steps:

A. arranging a first welding groove at the end part of the first pipe to be welded, arranging a second welding groove at the end part of the second pipe to be welded, enabling the first pipe to be welded and the second pipe to be welded to be obliquely arranged opposite to each other at intervals and fixed, enabling the first pipe to be welded to be positioned above the first pipe to be welded, and enabling the position between the first pipe to be welded and the second pipe to be welded to be a welding position;

B. welding a backing weld, specifically: firstly, arc is extinguished immediately at the bottom of a welding position after arc striking is carried out on the root part of the pipe wall of a first pipe to be welded to form a first welding point; then, arc is extinguished immediately after arc striking is carried out on the bottom of the welding position and the root of the pipe wall of the second pipe to be welded to form a second welding point; then, arc quenching is carried out after a molten pool is formed between the first welding spot and the second welding spot in a spot welding mode, and a third welding spot connecting the first welding spot and the second welding spot is formed; the first welding spot, the second welding spot and the third welding spot form an initial priming solidification molten pool; then, arc striking is carried out at the middle root position beside the initial bottoming solidification molten pool, when the molten pool is observed to expand to a first welding groove and a second welding groove, arc is instantly extinguished to form a bottoming solidification molten pool, and then a rear bottoming solidification molten pool is formed beside the previous bottoming solidification molten pool in a welding mode; then, repeating the welding for multiple times, and welding two sides of the initial bottoming solidification molten pool to form multiple bottoming solidification molten pools until the bottoming solidification molten pools are folded at the top end of the welding position;

C. welding a cover surface welding line outside the backing welding line A, which specifically comprises the following steps: firstly, welding the bottom of a welding position, striking an arc on a first welding groove, immediately swinging a welding gun to a second welding groove after a molten pool is fused with the first welding groove, and immediately extinguishing the arc to form a cover solidification molten pool after the molten pool is fused with the second welding groove; then, repeating for multiple times, and welding the latter cover surface solidification molten pool beside the former cover surface solidification molten pool until the cover surface solidification molten pool is folded at the top of the welding position; the latter hardfacing solidification bath covers at least one-half of the former hardfacing solidification bath.

Further, the method comprises the following steps: the number of the cover surface welding lines is two layers.

The invention has the beneficial effects that: the invention converts the continuous welding in the circumferential direction into a plurality of arc-breaking welding in the linear direction, is beneficial to controlling the angle of the welding gun during welding and is easy to ensure the quality and the shape of the welding seam. Through analysis, the reason for the defects of the backing weld in the background technology is that the backing weld is narrow, the welding wire is high in melting speed, the swing of the welding wire towards two sides is limited, the middle temperature of the weld is overhigh, the step B can avoid the condition, the quality of the backing weld is ensured, and meanwhile, the wire breakage of the welding wire can be avoided. The step C can avoid the generation of internal welding beading. In conclusion, the invention can effectively control the welding defects and ensure the welding quality.

Drawings

FIG. 1 is a diagram of an initial bottoming solidification bath weld;

FIG. 2 is a schematic view of a backing weld;

FIG. 3 is a weld map of the solidification weld pool of the cover;

FIG. 4 is a schematic view of a weld seam for tube-to-tube welding;

labeled as: the welding method comprises the following steps of firstly welding a pipe to be welded 1, a first welding groove 2, secondly welding a pipe to be welded 3, a second welding groove 4, a welding position 5, a first welding point 6, a second welding point 7, a third welding point 8, an initial bottoming solidification molten pool 9, a bottoming welding line 10, a bottoming solidification molten pool 11, a cover surface solidification molten pool 12 and a cover surface welding line 13.

Detailed Description

The invention is further described with reference to the following figures and detailed description.

The method for welding the inclined pipe by using the MAG welding comprises the following steps: A. arranging a first welding groove 2 at the end part of a first pipe to be welded 1, arranging a second welding groove 4 at the end part of a second pipe to be welded 3, enabling the first pipe to be welded 1 and the second pipe to be welded 3 to be obliquely arranged opposite to each other at intervals and fixed, enabling the first pipe to be welded 1 to be positioned above, and enabling the position between the first pipe to be welded 1 and the second pipe to be welded 3 to be a welding position 5;

B. welding a backing weld 10, specifically: firstly, arc extinguishing is carried out immediately after arc striking is carried out at the bottom of a welding position 5 and the root of the pipe wall of a first pipe to be welded 1 to form a first welding point 6; then, arc extinguishing is carried out immediately after arc striking is carried out at the bottom of the welding position 5 and the root part of the pipe wall of the second pipe to be welded 3 to form a second welding point 7; then, arc quenching is carried out after a molten pool is formed between the first welding spot 6 and the second welding spot 7 through spot welding, and a third welding spot 8 for connecting the first welding spot 6 and the second welding spot 7 is formed; the first welding point 6, the second welding point 7 and the third welding point 8 form an initial priming solidification molten pool 9; then, arc striking is carried out at the middle root position beside the initial bottoming solidification molten pool 9, when the molten pool is observed to expand to the first welding groove 2 and the second welding groove 4, arc is immediately extinguished to form a bottoming solidification molten pool 11, and then the next bottoming solidification molten pool 11 is formed by welding beside the previous bottoming solidification molten pool 11; then, repeating the welding for a plurality of times, and welding at two sides of the initial bottoming solidification molten pool 9 to form a plurality of bottoming solidification molten pools 11 until the bottoming solidification molten pools 11 are folded at the top end of the welding position 5;

C. welding a cover surface welding seam 13 outside the backing welding seam 10, specifically: firstly, welding the bottom of a welding position 5, striking an arc on a first welding groove 2, immediately swinging a welding gun to a second welding groove 4 after a molten pool is fused with the first welding groove 2, and immediately extinguishing the arc to form a cover solidification molten pool 12 after the molten pool is fused with the second welding groove 4; then, repeating for multiple times, and welding the next cover surface solidification molten pool 12 beside the previous cover surface solidification molten pool 12 until the cover surface solidification molten pool 12 is folded at the top of the welding position 5; the latter solidification bath 12 covers at least half of the former solidification bath 12.

The cap weld 13 may be formed in a number of layers depending on the welding depth, and may be one layer, two layers or more.

When the welding gun is used for welding, particularly when a backing weld joint 10 is welded, the welding bead is narrow, the movement amount of a welding wire is small, and the welding gun is swung instead of swinging of an arm by adopting a mode of rotating a wrist.

Claims

A method for welding an inclined pipe by MAG welding is characterized in that: the method comprises the following steps:

A. a first welding groove (2) is formed in the end portion of a first pipe to be welded (1), a second welding groove (4) is formed in the end portion of a second pipe to be welded (3), the first pipe to be welded (1) and the second pipe to be welded (3) are enabled to be obliquely arranged opposite to each other and fixed at intervals, the first pipe to be welded (1) is located above the first pipe to be welded, and the position between the first pipe to be welded (1) and the second pipe to be welded (3) is a welding position (5);

B. welding a backing weld (10), in particular: firstly, arc quenching is carried out immediately after the arc striking is carried out at the bottom of a welding position (5) and the root of the pipe wall of a first pipe (1) to be welded to form a first welding point (6); then, arc quenching is carried out immediately after arc striking is carried out at the bottom of the welding position (5) and the root part of the tube wall of the second tube (3) to be welded to form a second welding spot (7); then, arc quenching is carried out after a molten pool is formed between the first welding point (6) and the second welding point (7) through spot welding, and a third welding point (8) connecting the first welding point (6) and the second welding point (7) is formed; the first welding point (6), the second welding point (7) and the third welding point (8) form an initial bottoming solidification molten pool (9); then, arc striking is carried out at the middle root position beside the initial bottoming solidification molten pool (9), when the molten pool is observed to expand to the first welding groove (2) and the second welding groove (4), arc is extinguished immediately to form a bottoming solidification molten pool (11), and then a next bottoming solidification molten pool (11) is formed beside the previous bottoming solidification molten pool (11) in a welding mode; then, repeating the welding for a plurality of times, and welding two sides of the initial bottoming solidification molten pool (9) to form a plurality of bottoming solidification molten pools (11) until the bottoming solidification molten pools (11) are folded at the top end of the welding position (5);

C. weld cap face welding seam (13) outside backing weld seam (10), specifically: firstly, welding the bottom of a welding position (5), striking an arc on a first welding groove (2), immediately swinging a welding gun to a second welding groove (4) after a molten pool is fused with the first welding groove (2), and immediately extinguishing the arc to form a cover solidification molten pool (12) after the molten pool is fused with the second welding groove (4); then, repeating for multiple times, and welding the next cover surface solidification melting pool (12) beside the previous cover surface solidification melting pool (12) until the cover surface solidification melting pool (12) is folded at the top of the welding position (5); the latter solidification bath (12) covers at least half of the former solidification bath (12).
2. The MAG weld of claim 1, a method of oblique pipe welding, comprising: the number of the cover surface welding seams (13) is two layers.