Laser wire filling welding method for boiler small-caliber pipe

Abstract

The invention relates to the technical field of boilers, and discloses a laser wire filling welding method for a boiler small-caliber pipe, and the laser wire filling welding method comprises the following steps: S1, carrying out groove processing on the small-caliber pipe to be welded, removing an oxidation film on the surface of a groove, and carrying out surface cleaning; s2, groove assembly is conducted on the small-caliber pipe to form a welding groove, and spot welding fixing is conducted on the welding groove through a laser filler wire welding technology; s3, argon is introduced into the back face area of the welding groove; s4, preheating the welding groove by adopting a laser self-fusion welding process; and S5, the welding groove is sequentially subjected to backing welding, filling welding and cosmetic welding through a laser filler wire welding process. The welding efficiency can be improved, and heat input can be reduced.

Description

Technical Field

[0001] This invention relates to the field of boiler technology, and more specifically, to a laser filler wire welding method for small-diameter boiler tubes. Background Technology

[0002] The boiler's water-cooled walls and other structural walls are all made up of multiple small-diameter pipes welded together. Currently, the commonly used welding method is hot-wire TIG multi-layer multi-pass welding. This welding method uses an electric arc for welding. Since the electric arc heat source has low energy density and is diffuse, a slow and high current method is required, resulting in low welding efficiency and high heat input, which in turn affects the welding quality. Summary of the Invention

[0003] The technical objective of this invention is to provide a laser filler wire welding method for small-diameter boiler tubes that can improve welding efficiency and reduce heat input, addressing the shortcomings of the prior art.

[0004] The technical solution adopted in this invention is as follows: A laser filler wire welding method for small-diameter boiler tubes, the laser filler wire welding method comprising the following steps: S1. Perform beveling on the small-diameter pipe to be welded, remove the oxide film from the bevel surface, and clean the surface. S2. The small-diameter pipes are beveled to form a welding bevel, and the welding bevel is spot-welded and fixed using laser filler wire welding process. S3. Introduce argon gas into the back area of ​​the weld bevel; S4. The weld bevel is preheated using a laser autofusion welding process; S5. The weld bevel is sequentially subjected to root pass welding, filler pass welding, and cover pass welding using laser filler wire welding process.

[0005] The above-mentioned technical measures can reduce defects such as porosity and lack of fusion and improve welding quality by removing the oxide film on the surface of the bevel and cleaning the surface; by introducing argon gas into the back area of ​​the weld bevel, excessive oxidation of the back area of ​​the weld bevel can be effectively prevented; by preheating the weld bevel, cold cracks caused by large temperature differences during welding can be avoided; by using laser filler wire welding process for root pass welding, filler weld welding and cover pass welding, heat input can be reduced, thereby reducing the probability of deformation, improving welding quality and dimensional accuracy, while reducing the amount of straightening work and improving welding efficiency.

[0006] Furthermore, the specific steps for removing the oxide film from the bevel surface in step S1 are as follows: The oxide film on the bevel surface is removed by mechanical grinding.

[0007] Furthermore, the specific steps for surface cleaning in S1 are as follows: The bevel surface was cleaned with anhydrous ethanol.

[0008] The above-mentioned technical measures, by using anhydrous ethanol for cleaning, can remove impurities such as moisture and fine dust, which is beneficial to improving welding quality.

[0009] Furthermore, the welding bevel is a U-shaped bevel.

[0010] Furthermore, the welding process parameters for spot welding and fixing the welding groove using laser filler wire welding in S2 are: laser power 2500W, defocusing amount -7mm, and wire feeding speed 1.6m / min.

[0011] The above-mentioned technical measures achieve rapid and reliable temporary positioning by controlling the welding process parameters of spot welding and precisely controlling the weld points.

[0012] Furthermore, the welding process parameters for preheating the weld bevel using laser autofusion welding in S4 are: laser power 2500W, defocusing amount -7mm, and welding speed 40mm / s.

[0013] The above-mentioned technical measures can rapidly increase the bevel temperature by controlling the welding process parameters during preheating.

[0014] Furthermore, the welding process parameters for the root pass welding in S5 are: laser power 5000W~5200W, defocusing amount -7mm, wire feed speed 2.0m / min~2.2m / min, welding speed 30mm / s, power rise time 50ms, and power fall time 500ms.

[0015] Furthermore, the welding process parameters for filler welding and cap welding in S5 are as follows: laser power 3000W~3700W, defocusing amount +25mm~+30mm, wire feed speed 1.3m / min~1.5m / min, welding speed 10mm / s, power rise time 50ms, and power fall time 500ms.

[0016] Furthermore, both the filler weld and the cap weld employ single-layer multi-pass welding.

[0017] The above-mentioned technical measures, by adopting a single-layer multi-pass welding method, can avoid collapse caused by excessive heat input at one time and reduce deformation.

[0018] Furthermore, the argon gas flow rate in S3 is 15 L / min.

[0019] One or more technical solutions provided by this invention have at least the following technical effects or advantages: This invention reduces defects such as porosity and incomplete fusion by removing the oxide film from the bevel surface and performing surface cleaning, thereby improving welding quality. By introducing argon gas into the back area of ​​the weld bevel, excessive oxidation of the back area of ​​the weld bevel can be effectively prevented. Preheating the weld bevel can avoid cold cracking caused by large temperature differences during welding. By using laser filler wire welding for root pass, fill pass, and cap pass welding, heat input can be reduced, thereby reducing the probability of deformation, improving welding quality and dimensional accuracy, while reducing the amount of straightening work and increasing welding efficiency. Attached Figure Description

[0020] The accompanying drawings, which are provided to further illustrate embodiments of the invention and constitute a part of this invention, are not intended to limit the scope of the invention. Figure 1 This is a schematic diagram of the welding bevel structure in this invention; Figure 2 This is a schematic diagram of the welding position in this invention; Among them, 1-small diameter pipe; 2-welding bevel; 3-laser emission point; 4-laser power descent point; 5-laser power descent point; A - Rotation direction. Detailed Implementation

[0021] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, where there is no conflict, the embodiments of the present invention and the features thereof can be combined with each other.

[0022] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0023] Example 1 Reference Figures 1-2 This embodiment provides a laser filler wire welding method for small-diameter boiler tubes. The laser filler wire welding method includes the following steps: S1. Perform beveling on the small-diameter pipe 1 to be welded, remove the oxide film on the bevel surface, and clean the surface. The specific steps for removing the oxide film from the bevel surface in S1 are as follows: removing the oxide film from the bevel surface by mechanical grinding. The specific steps for surface cleaning in S1 are as follows: cleaning the bevel surface with anhydrous ethanol.

[0024] S2. The small-diameter pipe 1 is beveled to form a welding bevel 2, and the welding bevel 2 is spot welded and fixed using laser filler wire welding process. Among them, welding groove 2 is a U-shaped groove.

[0025] The welding process parameters for spot welding and fixing the weld bevel 2 using laser filler wire welding in S2 are: laser power approximately 2500W, defocusing amount approximately -7mm, and wire feed speed approximately 1.6m / min. The spot welding position and number of spot welds are determined according to the actual situation and are not specifically limited in this embodiment.

[0026] S3. Introduce argon gas into the back area of ​​the welding groove 2; The argon gas flow rate in S3 is approximately 15 L / min.

[0027] S4. Preheat the welding groove 2 using laser autofusion welding process; Among them, the welding process parameters for preheating the welding groove 2 using laser autofusion welding in S4 are: laser power of about 2500W, defocusing amount of about -7mm, and welding speed of about 40mm / s.

[0028] S5. Laser filler wire welding process is used to perform root pass welding, filler weld and cover pass welding on weld groove 2 in sequence.

[0029] The welding process parameters for the root pass welding in S5 are as follows: laser power approximately 5000W, defocusing amount approximately -7mm, wire feed speed approximately 2.2m / min, welding speed approximately 30mm / s, power ramp-up time approximately 50ms, and power ramp-down time approximately 500ms.

[0030] The welding process parameters for filler and capping welding in S5 are as follows: laser power approximately 3000W, defocusing distance approximately +25mm, wire feed speed approximately 1.3m / min, welding speed approximately 10mm / s, power ramp-up time approximately 50ms, and power deceleration time approximately 500ms. Both filler and capping welding employ single-layer multi-pass welding. Specifically, the root pass welding consists of one weld pass, while the filler and capping welds consist of two weld passes. No cleaning is performed between each pass. The outer wall temperature of the small-diameter pipe 1 is approximately 100℃ during welding.

[0031] In this embodiment, the small-diameter pipe 1 to be welded is made of SA-210C+SA-210C pearlitic heat-resistant steel. The outer diameter of the small-diameter pipe 1 is about 57mm and the wall thickness is about 7.5mm.

[0032] During spot welding, preheating, root pass welding, fill pass welding, and cover pass welding, the small diameter pipe 1 is placed in the horizontal welding position of the flipping and rotating positioner, which drives the small diameter pipe 1 to rotate. The robot carries a laser and a laser welding head to perform corresponding operations on the welding bevel 2.

[0033] The preferred laser is the JPT-12000 fiber laser with a fiber core diameter of approximately 200μm; the preferred laser welding head is the PRECITEC YW52 laser welding head with a collimation focal length of approximately 150mm and a focusing focal length of approximately 300mm; the preferred robot is the ABB IRB2400 robot, and the preferred welding wire is ER50-6 Ø1.2 welding wire; the preferred flipping and rotating positioner is the IRBP A-250 positioner.

[0034] During the root pass, fill pass, and cap pass welding, the welding wire is fed 10ms in advance. 10ms later, the laser emits light at laser emission point 3, corresponding to laser power ramp-up point 5, where the laser power begins to ramp up. At the same time, the flipping and rotating positioner drives the small-diameter tube 1 to rotate along the rotation direction A to start welding. When the laser power ramp-down point 4 rotates 370° (i.e., corresponding to laser emission point 3), the laser power begins to ramp down. At this time, the welding wire is retracted 10ms late, and the small-diameter tube 1 continues to rotate until the laser power ramps down to 0W, at which point welding stops.

[0035] Example 2 The rest of the content of this embodiment is the same as that of embodiment 1, except that: The welding process parameters for the root pass welding in S5 are as follows: laser power approximately 5200W, defocusing amount approximately -7mm, wire feed speed approximately 2.0m / min, welding speed approximately 30mm / s, power ramp-up time approximately 50ms, and power ramp-down time approximately 500ms.

[0036] The welding process parameters for filler and capping welding in S5 are as follows: laser power approximately 3700W, defocusing distance approximately +30mm, wire feed speed approximately 1.5m / min, welding speed approximately 10mm / s, power ramp-up time approximately 50ms, and power deceleration time approximately 500ms. Both filler and capping welding employ single-layer multi-pass welding. Specifically, the root pass consists of one weld pass, while the filler and capping welds consist of four weld passes. No cleaning is performed between each pass. The outer wall temperature of the small-diameter pipe during welding is approximately 60℃.

[0037] In this embodiment, the small-diameter pipe to be welded is made of 12Cr1MoVG+SA213T91 material, with an outer diameter of about 57mm and a wall thickness of about 8mm. The welding wire is H08CrMoVA Ø1.2 welding wire.

[0038] Example 3 The rest of the content of this embodiment is the same as that of embodiment 1, except that: The welding process parameters for the root pass welding in S5 are as follows: laser power approximately 5100W, defocusing amount approximately -7mm, wire feed speed approximately 2.1m / min, welding speed approximately 30mm / s, power ramp-up time approximately 50ms, and power ramp-down time approximately 500ms.

[0039] The welding process parameters for filler and capping welding in S5 are as follows: laser power approximately 3500W, defocusing amount approximately +28mm, wire feed speed approximately 1.4m / min, welding speed approximately 10mm / s, power ramp-up time approximately 50ms, and power ramp-down time approximately 500ms.

[0040] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0041] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for laser filler wire welding of small-diameter boiler tubes, characterized in that: The laser filler wire welding method includes the following steps: S1. Perform beveling on the small-diameter pipe to be welded, remove the oxide film from the bevel surface, and clean the surface. S2. The small-diameter pipes are beveled to form a welding bevel, and the welding bevel is spot-welded and fixed using laser filler wire welding process. S3. Introduce argon gas into the back area of ​​the weld bevel; S4. The weld bevel is preheated using a laser autofusion welding process; S5. The weld bevel is sequentially subjected to root pass welding, filler pass welding, and cover pass welding using laser filler wire welding process.

2. The laser filler wire welding method for small-diameter boiler tubes according to claim 1, characterized in that: The specific steps for removing the oxide film from the bevel surface in S1 are as follows: The oxide film on the bevel surface is removed by mechanical grinding.

3. The laser filler wire welding method for small-diameter boiler tubes according to claim 1, characterized in that: The specific steps for surface cleaning in S1 are as follows: The bevel surface was cleaned with anhydrous ethanol.

4. The laser filler wire welding method for small-diameter boiler tubes according to claim 1, characterized in that: The welding bevel is a U-shaped bevel.

5. The laser filler wire welding method for small-diameter boiler tubes according to claim 1, characterized in that: The welding process parameters for spot welding and fixing the welding groove using laser filler wire welding in S2 are: laser power 2500W, defocusing amount -7mm, and wire feeding speed 1.6m / min.

6. The laser filler wire welding method for small-diameter boiler tubes according to claim 1, characterized in that: The welding process parameters for preheating the weld bevel using laser autofusion welding in S4 are: laser power 2500W, defocusing amount -7mm, and welding speed 40mm / s.

7. The laser filler wire welding method for small-diameter boiler tubes according to claim 1, characterized in that: The welding process parameters for the root pass welding in S5 are as follows: laser power 5000W~5200W, defocusing amount -7mm, wire feed speed 2.0m / min~2.2m / min, welding speed 30mm / s, power rise time 50ms, and power fall time 500ms.

8. The laser filler wire welding method for small-diameter boiler tubes according to claim 1, characterized in that: The welding process parameters for filler welding and cover welding in S5 are as follows: laser power 3000W~3700W, defocusing amount +25mm~+30mm, wire feed speed 1.3m / min~1.5m / min, welding speed 10mm / s, power rise time 50ms, and power fall time 500ms.

9. The laser filler wire welding method for small-diameter boiler tubes according to claim 1, characterized in that: Both the filler weld and the capping weld employ single-layer, multi-pass welding.

10. The laser filler wire welding method for small-diameter boiler tubes according to claim 1, characterized in that: The argon gas flow rate in S3 is 15 L / min.

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