Automatic submerged arc welding method for large-diameter flange

Abstract

The invention provides an automatic submerged arc welding method for a large-diameter flange, the method is based on welding device equipment, the welding device equipment comprises a roller frame, two side rollers capable of rotating are arranged on the roller frame, and a pipe to be welded is arranged between the two side rollers; a welding wire is arranged on the outer wall of the pipe to achieve welding of a circumferential weld joint of the pipe, and the large-diameter flange submerged-arc automatic welding method comprises the steps that during girth welding, it is determined that a molten pool rotates to a horizontal solidification position along with the pipe; and adjusting the position of the welding wire to the horizontal solidification position. Based on the welding device, the position of the welding wire is adjusted to the horizontal solidification position by determining the rotation horizontal solidification position of a molten pool, and therefore the welding quality of the large-diameter flange welding seam is improved.

Description

Technical Field:

[0001] The present invention relates to the field of welding, and in particular to a submerged arc automatic welding method for large-diameter flanges. Background Art:

[0002] Currently, the FCAW (CO2 flux-cored wire) method used in the welding production of flanges and pipes has room for improvement in welding production efficiency, with a relatively high labor intensity. During the welding process, there is intense arc radiation and a large amount of fumes. The welding quality is greatly affected by factors such as the skill level of the welder and the ambient temperature of the working environment. According to the existing production site conditions, there is no need to use lifting equipment to change the welding position of the flange. By changing the welding method and implementing technological innovation, the welding efficiency and quality of pipe flanges can be improved.

[0003] There is an urgent need for a submerged arc automatic welding method for large-diameter flanges, which helps to solve the technical problem in the prior art of lacking a submerged arc automatic welding method for large-diameter flanges and improving the welding quality of large-diameter flange welds. Summary of the Invention:

[0004] In one embodiment, the present invention provides a submerged arc automatic welding method for large-diameter flanges. Based on welding device equipment, by determining the horizontal solidification position of the molten pool rotation, the position of the welding wire is adjusted to the horizontal solidification position, thereby solving the technical problem of improving the welding quality of large-diameter flange welds.

[0005] The method is based on welding device equipment. The welding device equipment includes a roller rack. Rotatable rollers are provided on both sides of the roller rack. A pipe to be welded is arranged between the two rollers on both sides. A welding wire is arranged on the outer wall of the pipe to achieve welding of the circumferential weld of the pipe. The submerged arc automatic welding method for large-diameter flanges includes:

[0006] During circumferential weld welding, determine that the molten pool rotates with the pipe to the horizontal solidification position;

[0007] Adjust the position of the welding wire to the horizontal solidification position.

[0008] In one embodiment, during the welding of the outer seam of the pipe, the welding wire should be in the downhill position, offset by d = 15 - 25 mm from the vertical center line of the pipe.

[0009] In one embodiment, during the welding of the flange at the pipe end, one layer of backing weld and two layers of capping weld are performed. Before welding, fix the submerged arc welding trolley on the mobile platform and align the welding wire and the infrared guiding lamp on the same straight line;

[0010] When starting the arc, first ignite the arc, and then immediately start the roller rack to drive the rotation of the pipe cylinder. When stopping the arc, weld about 10 mm - 20 mm past the starting arc end to completely melt the starting arc section weld, and then stop welding.

[0011] In one embodiment, the flange is made of Q235A, with an inner diameter of 512 mm and a thickness of 30 mm.

[0012] In one embodiment, the pipe is made of 20# seamless steel pipe, with a pipe diameter of 508 mm and a wall thickness of 13 mm.

[0013] In one embodiment, the submerged arc automatic welding machine is connected with direct current reverse polarity, and the wire diameter

[0014] In one embodiment, the reference range of welding current is 440 - 600 A, the reference range of arc voltage is 25 - 27 V, and the reference range of welding speed is 329 mm / min - 476 mm / min.

[0015] In one embodiment, the included angle between the wire and the flange vertical plate is 40 - 45°, and during welding, the position of the wire needs to be appropriately shifted outward by 1 - 2 mm after aligning with the root center line, reducing the arc heat received by the vertical plate, avoiding undercut, and minimizing the deposited metal flowing downward.

[0016] In one embodiment, during welding, the position of the wire is at the middle of the highest point of the arc of the vertical plate and the cover layer 1 weld.

[0017] In one embodiment, during welding, the position of the wire is at the lower weld toe of the root pass weld bead, achieving the required lower weld leg size of the weld and increasing the weld thickness. Description of the drawings:

[0018] Figure 1 This is a schematic diagram of the physical object of the welding torch fixing device in one embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of a submerged arc automatic welding method for large - diameter flanges in another embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of good appearance formation during and after flange welding in another embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of meeting the requirements of no surface welding defects in PT non - destructive testing in another embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of the adjustment range of the wire angle in another embodiment of the present invention;

[0023] Figure 6 This is a schematic diagram of a reasonable wire position of the wire angle in another embodiment of the present invention. Specific embodiments:

[0024] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0025] Reference is made herein to the various aspects and features of the present application with reference to the accompanying drawings.

[0026] These and other features of the present application will become apparent from the following description of the preferred forms of the embodiments given as non-limiting examples with reference to the accompanying drawings.

[0027] It should also be understood that although the present application has been described with reference to some specific examples, those skilled in the art can surely implement many other equivalent forms of the present application, which have the features as described in the claims and thus are all within the scope of protection defined hereby.

[0028] When combined with the accompanying drawings, the above and other aspects, features and advantages of the present application will become more apparent in view of the following detailed description.

[0029] Hereinafter, specific embodiments of the present application will be described with reference to the accompanying drawings; however, it should be understood that the embodiments claimed are merely examples of the present application and can be implemented in various ways. Well-known and / or repetitive functions and structures have not been described in detail to determine the true intention based on the user's historical operations and to avoid unnecessary or redundant details from obscuring the present application. Therefore, the specific structural and functional details claimed herein are not intended to be limiting, but are merely used as a basis for the claims and a representative basis for teaching those skilled in the art to use the present application in substantially any suitable detailed structure in a variety of ways.

[0030] This specification may use the phrase "in one embodiment", "in another embodiment", "in yet another embodiment" or "in other embodiments", which may each refer to one or more of the same or different embodiments according to the present application.

[0031] Modify and add a welding torch angle rotating sleeve to change the welding torch angle of submerged arc automatic welding from a fixed vertical angle to an adjustable angle within the range of 0 to 45° (the included angle between the vertical plate and the pipe plane);

[0032] Research the application of the submerged arc automatic welding method (SAW) from the commonly used butt welding to the welding of pipe flanges;

[0033] Solve the main problems and technical difficulties of submerged arc automatic welding in the 2F welding position (the welding speed is relatively fast, it is not easy to obtain a good weld formation, the molten metal melted by the arc flows downward under the action of gravity, and it is easy to produce undercut defects on the vertical plate, etc.).

[0034] The deposited metal is the weld metal formed entirely by the melting of the filler metal. It is the melted part of the electrode or welding wire in the weld.

[0035] Figure 1 This is a schematic diagram of the physical object of the welding torch fixing device in an embodiment of the present invention. Figure 2 This is a schematic diagram of a submerged arc automatic welding method for large-diameter flanges in another embodiment of the present invention; Figure 3 This is a schematic diagram showing good appearance formation during and after the flange welding process in another embodiment of the present invention; Figure 4 This is a schematic diagram showing that the PT non-destructive testing has no surface welding defects and meets the requirements in another embodiment of the present invention; Figure 5 This is a schematic diagram of the adjustment range of the wire angle in another embodiment of the present invention; Figure 6 This is a schematic diagram of a reasonable wire position of the wire angle in another embodiment of the present invention.

[0036] Such as Figures 1 to 6 As shown, in one embodiment, the present invention provides a submerged arc automatic welding method for large-diameter flanges. The method is based on welding device equipment. The welding device equipment includes a roller stand. Rotatable rollers are provided on both sides of the roller stand. A pipe to be welded is arranged between the two rollers on both sides. A welding wire is arranged on the outer wall of the pipe to realize the welding of the circumferential weld of the pipe. The submerged arc automatic welding method for large-diameter flanges includes:

[0037] S101. During circumferential weld welding, determine that the molten pool rotates with the pipe to the horizontal solidification position.

[0038] S102. Adjust the position of the welding wire to the horizontal solidification position.

[0039] A sleeve and an inner hexagon fixing screw are added in the middle of the original fixed connecting rod, and the angle of the welding torch (welding wire) can be rotated and adjusted by 0-45° (the angle between the vertical plate and the pipe plane). During the horizontal fillet welding of the flange, after rotating to the required angle, tighten the top screw to complete the adjustment of the angle of the welding torch (welding wire).

[0040] In one embodiment, during the welding of the outer seam of the pipe, the welding wire should be in the downhill position and offset from the vertical center line of the pipe by a range of d = 15-25 mm.

[0041] Flange welding

[0042] Pre-welding preparation

[0043] The pre-welding preparation includes work such as grinding and cleaning rust, oil stains, etc. within 20 mm of the welding area of the flange and the pipe, and baking the welding flux.

[0044] Roller stand

[0045] The roller rack is an essential equipment for circumferential seam welding of pipes. The motor drives the driving rollers through a speed reducer, and the driving rollers rotate the pipe cylinder by means of friction. The roller rack can adjust the rotational speed of the rollers, thus changing the rotational speed of the pipe cylinder, that is, changing the welding speed. The distance between the two rollers can be adjusted to meet the needs of pipes with different diameters.

[0046] Wire position (wire offset distance)

[0047] During submerged arc welding in the flat welding position, the molten pool cools and solidifies in the horizontal position, and the weld formation is good. During circumferential seam submerged arc automatic welding, from the formation to the solidification of the molten pool, due to the continuous rotation of the roller tire rack, the spatial position is also constantly changing. If the wire is at the highest point of the weld seam, with a relatively fast welding speed, the deposited metal formed by the molten pool will solidify from the horizontal position to the inclined position, resulting in poor weld formation. Therefore, during circumferential seam welding, the correct wire position is that the molten pool follows the rotation of the pipe to solidify in the horizontal position, and the weld formation is the best. When welding the outer seam of the pipe, the wire should be in the downhill position and offset 15 - 25 mm from the vertical center line of the pipe. The appropriate offset distance should be adjusted according to the welding speed. If the offset distance is too large, the molten pool will cool and solidify before reaching the horizontal position; if the offset distance is too small, the molten pool will cool and solidify after passing the horizontal position, both of which will result in poor weld formation.

[0048] In one embodiment, when welding the flange at the pipe end, one layer of backing weld and two layers of capping weld are performed. Before welding, the submerged arc welding trolley is fixed on the moving platform, and the wire and the infrared guiding lamp are calibrated on the same straight line;

[0049] When starting the arc, first ignite the arc, and then immediately start the roller rack to drive the pipe cylinder to rotate. When stopping the arc, weld about 10 mm - 20 mm past the starting arc end to completely penetrate the weld of the starting arc section, and then stop welding.

[0050] In one embodiment, the flange material is Q235A, with an inner diameter of 512 mm and a thickness of 30 mm.

[0051] In one embodiment, the pipe material is 20# seamless steel pipe, with a pipe diameter of 508 mm and a wall thickness of 13 mm.

[0052] In one embodiment, the submerged arc automatic welding machine is connected with direct current reverse polarity, and the wire diameter

[0053] In one embodiment, the reference range of welding current is 440 - 600 A, the reference range of arc voltage is 25 - 27 V, and the reference range of welding speed is 329 mm / min - 476 mm / min.

[0054] In one embodiment, the included angle between the welding wire and the flange vertical plate is 40 - 45°. During welding, after aligning the welding wire position with the root center line, it needs to be appropriately shifted outward by 1 - 2 mm to reduce the arc heat received by the vertical plate, avoid undercut, and minimize the deposited metal flowing downward.

[0055] In one embodiment, during welding, the welding wire position is at the middle of the highest point of the arc of the vertical plate and the cover layer 1 weld.

[0056] In one embodiment, during welding, the welding wire position is at the lower weld toe of the root pass weld bead to achieve the required lower weld leg size of the weld and increase the weld thickness.

[0057] The welding process and parameters of this method are as follows: The flange material is Q235A, with an inner diameter of 512 mm and a thickness of 30 mm. The pipe material is 20# seamless steel pipe, with a pipe diameter of 508 mm and a wall thickness of 13 mm. The welding position is 1G (realized by rotating with a roller stand), the submerged arc automatic welding machine is DC reverse connection, and the welding wire diameter The reference range of the welding current is 440 - 600 A, the reference range of the arc voltage is 25 - 27 V, and the reference range of the welding speed is 329 mm / min - 476 mm / min (the speed of welding = the rotation speed of the roller tire stand).

[0058] The specific welding operation method is as follows:

[0059] To solve the problem of the molten metal flowing downward, a welding process method of using a thin welding wire, small current, and fast welding is required during welding. When welding a transverse fillet weld with a large weld leg size, the phenomenon of one-sided weld leg will inevitably occur, and a single-pass weld cannot obtain a large weld leg size that meets the requirements. To obtain a sufficient weld leg size (10 - 15 mm), it is necessary to carry out one root pass and two cover layers of welding (see the following figure). Before welding, fix the submerged arc welding trolley on the moving platform and calibrate the welding wire and the infrared guiding lamp on the same straight line. When starting the arc, first ignite the arc, and then immediately start the roller stand to drive the pipe cylinder to rotate. When stopping the arc, weld 10 mm - 20 mm or so past the starting arc end to completely penetrate the starting arc section of the weld, and then stop welding. The starting arc section of the weld and the interlayer do not need to be polished. Adjust the welding process parameters according to the weld leg size and weld thickness of the previous weld and the welding size and thickness required for the weld to be welded.

[0060] Root pass: The included angle between the welding wire and the vertical plate (flange) is 40 - 45°. During welding, after aligning the welding wire position with the root center line, it needs to be appropriately shifted outward by 1 - 2 mm to reduce the arc heat received by the vertical plate, avoid undercut, and minimize the deposited metal flowing downward. The upper and lower weld leg sizes of the root pass should be basically the same to ensure complete penetration of the weld root. The main requirements and functions are to achieve the required amount of filler metal and appropriate weld leg size.

[0061] Welding process parameter range: welding current 530 - 570A, arc voltage 25 - 27V, welding speed 476mm / min.

[0062] Cover layer 1: The angle between the welding wire and the vertical plate (flange) is 35 - 40°, and the position of the welding wire during welding is at the weld toe at the lower opening of the root pass weld bead. The main requirements and functions are to achieve the required lower fillet size of the weld and increase the weld thickness (relatively slow welding speed).

[0063] Welding process parameter range: welding current 560 - 600A, arc voltage 25 - 27V, welding speed 329mm / min.

[0064] Cover layer 2: The angle between the welding wire and the vertical plate (flange) is 40 - 45°, and the position of the welding wire during welding is at the middle of the highest point of the arc of the vertical plate and the weld of cover layer 1. The main requirements and functions are to have a smooth transition and combination with cover layer 1, ensure the required fillet size at the upper opening of the weld and no undercut defect.

[0065] Welding process parameter range: welding current 440 - 480A, arc voltage 25 - 26V, welding speed 476mm / min.

[0066] Beneficial effects:

[0067] Improve welding efficiency, greatly improve and reduce the labor intensity of welders (reduce arc radiation and welding fumes), and enhance welding quality;

[0068] Under the existing production conditions, there is no need to lift and change the welding position of the flange, and it can meet the welding operations of all lengths of pipes.

[0069] The above embodiments are only exemplary embodiments of the present invention and are not used to limit the present invention. The protection scope of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent replacements within the essence and protection scope of the present invention, and such modifications or equivalent replacements should also be regarded as falling within the protection scope of the present invention.

Claims

1. A large-diameter flange submerged arc automatic welding method, characterized in that: The method is based on a welding device, which includes a roller rack, on which rollers on both sides of the roller rack are rotatable, a pipe to be welded is arranged between the rollers on both sides, and a welding wire is arranged on the outer wall of the pipe to achieve welding of the circumferential weld of the pipe. The large-diameter flange submerged arc automatic welding method includes: During circumferential welding, ensure that the molten pool rotates with the pipe to a horizontal solidification position; The welding wire position is adjusted to the horizontal solidification position.

2. The large-diameter flange submerged arc automatic welding method according to claim 1 is characterized in that: When welding the outer seam of the pipe, the welding wire should be in a downhill position and offset from the vertical center line of the pipe by d = 15 to 25 mm.

3. The large-diameter flange submerged arc automatic welding method according to claim 2 is characterized in that: When welding the pipe end flange, a base layer and two cover layers are welded. Before welding, the submerged arc welding carriage is fixed on the mobile platform, and the welding wire and the infrared guide light are aligned on the same straight line; When striking the arc, first ignite the arc, then start the roller frame to drive the tube body to rotate. When ending the arc, weld about 10mm to 20mm past the arc starting end and completely melt the arc striking section weld before ending the arc and stopping welding.

4. The large-diameter flange submerged arc automatic welding method according to claim 3 is characterized in that: The flange material is Q235A, the inner diameter is 512mm and the thickness is 30mm.

5. The large-diameter flange submerged arc automatic welding method according to claim 4 is characterized in that: The pipe is made of 20# seamless steel pipe with a diameter of 508mm and a wall thickness of 13mm.

6. The large-diameter flange submerged arc automatic welding method according to claim 5, characterized in that: Submerged arc automatic welding machine DC reverse connection, welding wire diameter 7. The large-diameter flange submerged arc automatic welding method according to claim 6, characterized in that: The welding current reference range is 440~600A, the arc voltage reference range is 25~27V, and the welding speed reference range is 329mm / min~476mm / min.

8. The large-diameter flange submerged arc automatic welding method according to claim 7, characterized in that: The angle between the welding wire and the flange vertical plate is 40-45°. During welding, the welding wire position needs to be appropriately moved outward by 1-2 mm after aligning with the center line of the root to reduce the arc heat received by the vertical plate, avoid undercutting, and minimize the downward flow of deposited metal.

9. The large-diameter flange submerged arc automatic welding method according to claim 8, characterized in that: During welding, the welding wire is positioned at the middle of the highest point of the arc of the weld between the vertical plate and the cover layer 1.

10. The large-diameter flange submerged arc automatic welding method according to claim 9, characterized in that: During welding, the welding wire is positioned at the lower weld toe of the base weld to achieve the required lower weld leg size of the weld and increase the weld thickness.

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