CN115178868A - Laser wire filling welding method for thick plate - Google Patents

Abstract

The invention discloses a laser welding method for thick plates. Pre-opening grooves with certain truncated edge height on a group of thick plates and butting the grooves to form a combined part, irradiating a laser beam on the butting position of the combined part, providing a first welding wire which is uniformly conveyed at a certain speed at the front, directly irradiating the laser beam on the end point position of the welding wire, and providing a second welding wire which is uniformly conveyed at a certain speed at the rear, wherein the second welding wire has a certain distance with the laser beam irradiation position and the laser beam irradiation center has a certain height; the second welding wire is arranged at the rear part for feeding, so that the laser energy reflected by the first welding wire and high-temperature plasma formed when the laser beam melts the first welding wire can be fully utilized, and the second welding wire is melted, so that the utilization rate of the laser energy is improved, the quantity of stacked welding seams during single welding is increased, the welding pass of thick plates is reduced, and the manufacturing efficiency is improved; in addition, the cooling speed of the welding seam can be reduced through the melting of the second welding wire, so that the fluidity of the welding seam is improved, and the welding defect is avoided.

Description

A method for laser wire filler welding of thick plates

technical field

The invention relates to the field of laser welding, in particular to a welding method for suppressing welding defects, improving the utilization rate of laser energy and increasing the penetration depth for laser welding of medium and thick plates.

Background technique

At present, there is an increasing demand for structures with higher performance and larger thickness in industrial fields such as nuclear power equipment, marine engineering, shipbuilding, petrochemical, aerospace, etc., so the requirements for thick plate welding technology have also changed. getting higher and higher. When using traditional arc welding or gas shielded welding to weld thick plates, there are many limitations such as low production efficiency, high production cost, large post-weld deformation and so on. Compared with traditional welding methods, high-energy-density laser welding has the characteristics of small overall heat input, fast welding speed, large depth-to-width ratio of welds, and high welding accuracy, which can improve the production efficiency of enterprises, reduce costs and improve The quality of the processed products, so the high-power laser welding method has been more and more popularized and applied in the welding process of thick plates.

Laser wire filler welding was developed to weld large thickness workpieces. However, in the laser wire filling welding project, a large amount of energy irradiated by the laser beam on the welding wire is reflected. Although the power density increases and the temperature of the welding wire increases, the absorption rate of the laser beam by the welding wire will increase. However, a large amount of energy is still reflected and wasted; at the same time, a large amount of high-temperature plasma energy generated during the welding process will also be wasted. Moreover, in the current laser wire filling welding, due to the low energy of the laser beam melting the welding wire, the wire feeding speed is slow and the filling amount of the single layer is small, and the welding of thick plates requires more passes. When the laser power density is increased in order to increase the thickness of the single-layer filling wire and the wire feeding speed of the welding wire is increased, it is easy to form unstable small holes in the workpiece and the welding wire fusion is unstable, resulting in poor welding seam formation and internal unfusion. , pores and splashes. At present, the method of improving the quality of welding seam is mainly through matching the laser energy with parameters such as welding wire speed and welding speed, or adding energy field regulation such as electromagnetic field and ultrasonic wave, and also including, for example, by oscillating the laser beam and preheating and softening the welding wire to improve the quality of welding. The utilization rate of laser beam energy and the improvement of weld formation; however, the utilization rate of laser beam energy has not been greatly improved at all, and the laser beam reflected by the welding wire and molten pool has not been effectively utilized.

Therefore, there is an urgent need in the art for an energy-saving, low-cost, high welding quality laser wire filling welding method for medium and thick plates, so as to improve the utilization rate of laser energy, and improve the defects such as spatter, porosity, and lack of fusion in the welding process. Seam forming quality, and realize the realization of high-efficiency large-volume high-volume welding, and more efficient welding of thick plates.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method to solve the problems of low utilization rate of laser beam energy, less build-up of single-pass welds, and many welding defects during laser wire filling welding of medium and thick plates, and to improve welding quality and efficiency. Therefore, here is a solution:

Provided is a laser wire filler welding method for medium and heavy plates, the method comprising the following steps:

1) Provide a pair of first metal workpiece and second metal workpiece for welding, first welding wire, second welding wire and laser beam for laser welding; process the first metal workpiece and the second metal workpiece respectively A groove with a certain blunt edge height and an opening angle, and the two workpieces have a first welding surface, a second welding surface and a welding side surface opposite up and down; the first metal workpiece and the side surface of the second metal workpiece are butted to form the to-be-welded Assemblies and butt wires;

2) The laser beam is emitted to travel along the direction of the assembly butt line, the laser beam forms an irradiation area at the butting position, the first welding wire is transported to the laser beam irradiation area at a certain speed and contacts the assembly butt line, and the second welding wire is Transported to the vicinity of the laser beam irradiation area at a certain speed;

3) advancing the laser beam, the first welding wire and the second welding wire along the butt line at a certain speed, the laser beam melts the first welding wire, the second welding wire and the butt joint of the assembly, and forms a weld after cooling and solidification;

The first welding wire is irradiated by the laser beam to melt and generate high-temperature plasma, and the reflected beam and high-temperature plasma of the laser beam when irradiating the first welding wire heat the second welding wire to melt the first welding wire. It is located at the front end of the welding direction, and the second welding wire is located at the rear end of the laser beam in the welding direction; the wire feeding speed of the first welding wire is not less than 5m/min, and the wire feeding speed of the second welding wire does not exceed the feeding speed of the first welding wire; and the laser beam The irradiation power density on the first welding wire is not less than 10 ⁶ W/cm ² .

In a preferred embodiment, the melting of the second welding wire is achieved by melting the reflected light of the laser beam in the first welding wire and the molten pool and the formed high-temperature plasma.

In a preferred example, the end of the second welding wire has a height h2 from the butt line of the assembly, h2>0.5mm; and the end of the second welding wire has a horizontal distance b2 from the laser beam irradiation center, generally b2≥1mm.

In a preferred example, there is a shielding gas between the laser beam and the first welding wire, the shielding gas blows the high-temperature plasma generated during the welding process to the direction of the second welding wire, and the shielding gas flow rate is 10-100L /min;

In a preferred embodiment, the welding process includes that the laser beam has irradiated the material for a certain time before the first welding wire and the second welding wire are transported to the position, and the time does not exceed 1 second, preferably 0.5 seconds;

In a preferred embodiment, the welding process includes the laser beam re-entering after the first welding wire and the second welding wire are stopped.

Irradiation for a certain period of time, the period of time is not more than 1 second, preferably 0.5 seconds;

In a preferred example, the welding speed during the welding process is 0.3-1.0 m/min;

In a preferred example, the angle between the laser beam and the first welding wire is 40°-75°, and the angle between the second welding wire and the laser beam is 30°-70°;

In a preferred example, the wire feeding speed of the second welding wire does not exceed 0.8 times the wire feeding speed of the first welding wire;

In a preferred example, the first welding wire and the second welding wire are solid welding wires with the same composition and diameter.

Technical mechanism: The present invention makes full use of the laser energy reflected by the first welding wire and the molten pool to melt the second welding wire by adding a second welding wire that is continuously conveyed behind the laser beam during laser wire filling welding, so that it fills and fuses into the welding process. In the seam, the melting amount of the single-pass welding is increased, and the single-pass welding thickness is increased without additional energy input. At the same time, due to the slow feeding speed of the second welding wire, the molten pool is stable and provides a post-heat treatment for the welding seam. The fluctuation of the molten pool is reduced, providing more heat input to the molten pool, and the cooling rate of the molten pool is reduced, which helps to fully melt the base metal and improve welding defects such as non-fusion.

Description of drawings

In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only These are some embodiments of the present invention, and for those of ordinary skill in the art, other alternative embodiments can also be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic flow chart of the method of the present invention when welding stacks.

FIG. 2 is a schematic diagram of the shape of the groove of the workpiece.

3 is a schematic diagram of the mutual positional relationship between the laser beam, the first welding wire, the second welding wire and the shielding gas and the workpiece during welding by the method of the present invention.

FIG. 4 is an enlarged schematic diagram of the mutual positional relationship between the local laser beam, the first welding wire, the second welding wire and the workpiece surface.

FIG. 5 is a schematic diagram of the laser beam involved in the present invention when the laser beam scans and travels in a zigzag line.

FIG. 6 is a schematic diagram of the laser beam involved in the present invention when the sinusoidal scanning travels

FIG. 7 is a schematic diagram of the cross-sectional formation of ordinary laser wire filler welding.

FIG. 8 is a schematic diagram of the welding wire forming and melting process of the method of the present invention.

FIG. 9 is a schematic diagram of the cross-sectional forming of the welding seam formed by the method of the present invention.

FIG. 10 is a schematic flow chart of the welding method of the present invention.

Reference numerals: 1-first metal workpiece; 2-second metal workpiece; 11-first metal workpiece top surface; 12-second metal workpiece bottom surface; 13-first metal workpiece side surface; 14-first metal workpiece 15-bevel fillet; 16-bevel bottom width; 17-bevel side; 21-second metal workpiece top surface; 22-second metal workpiece bottom surface; 3-laser beam; 4-first Welding wire; 5-second welding wire; 6-shielding gas pipe; 7-shielding gas; 31-laser beam centerline; 32-plasma; 33-laser beam travel path; 41-first welding wire droplet; 42-second welding wire Droplet; 111-Unfused Defect; 112-Blowhole Defect; 121-Assembly Butt Centerline; B1-Assembly Bottom Butt Gap; B2-Assembly Top Butt Gap; γ-Groove Angle; The angle between the workpiece plane; β-the angle between the second welding wire and the workpiece plane; b2-the angle between the second welding wire and the central axis of the laser beam; h1-the height between the end point of the first welding wire and the plane of the workpiece; h2-the height between the end point of the second welding wire and the plane of the workpiece ; B3 - width of oscillating laser beam; s1 - filler wire welding seam of the first layer; s2 - filler wire welding seam of the second layer; s3 - filler wire welding seam of the third layer; s4 - filler wire welding seam of the fourth layer sew;

Detailed ways

After extensive and in-depth research, the present inventor found that a selective laser sintering method has beneficial effects, and completed the present invention on this basis.

The present invention will be further described below in conjunction with specific embodiments. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. Furthermore, the drawings are schematic representations, and thus the apparatus and apparatus of the present invention are not limited by the size or scale of the schematic representations.

It should be noted that, in the claims and description of this patent, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or Any such actual relationship or order between these entities or operations is implied. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device that includes a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a" does not preclude the presence of additional identical elements in a process, method, article, or device that includes the element.

Referring now to FIG. 1 , firstly, the metal workpieces 1 and 2 are butted to form a butt assembly and a butt centerline 121, and the butt gap is B, generally B is 0-2.0mm, preferably 0.1-1.0mm; wherein the metal workpiece 1 and 2 have a thickness t, which is generally not less than 5 mm, and preferably not less than 10 mm; and have top surfaces 11, 21 and bottom surfaces 12, 22, respectively. The metal workpieces 1 and 2 are respectively processed with grooves before butting, and the grooves have a blunt edge 14 and an opening 17 at the upper end. As shown in Figure 2, the height of the blunt edge 14 of the groove is generally 2-15mm, preferably 3-10mm The width of the groove bottom surface 16 is b, generally b is 1-3mm, preferably 1.5-2.5mm; and the angle between the groove side 17 and the abutting surface is γ, generally it is 0-5°, preferably is 1-3°, there is generally a transition arc surface 15 between the side surface 17 and the bottom surface 16, and its arc radius is 0.5-3mm, preferably 1-2mm; the metal workpieces 1 and 2 are processed according to the groove. After completion, the sides are butted to form an assembly, and the top of the assembly forms a gap B2, which is generally 2-8mm; preferably 3-6mm, forming a butt center line 121;

A laser beam 3 is provided to travel along the centerline 18 at the welding speed V, and the first welding wire 4 and the second welding wire 5 are provided uniformly conveyed at a certain speed, wherein the laser beam forms an irradiation spot on the surface of the end point of the first welding wire, and its power density Not less than 10 ⁶ W/cm2, when the light spot is a circular shape, its diameter is generally 0.1-1.0mm, preferably 0.3-0.6mm; the first welding wire is located at the front end of the laser beam consistent with the welding direction, and the second The welding wire is located at the rear end of the laser beam in the welding direction; the laser beam irradiates the first welding wire to melt it and generate high-temperature plasma, and the reflected beam and high-temperature plasma of the laser beam when irradiating the first welding wire heat the first welding wire. The second welding wire is melted, as shown in Figure 3 and Figure 4; the wire feeding speed V1 of the first welding wire is not less than 5m/min, preferably 5-15m/min, and the wire feeding speed V2 of the second welding wire is not more than the first welding wire. The wire feeding speed of the welding wire is preferably no more than 0.8 times the first wire feeding speed V1;

The first welding wire 4 and the laser beam 3 have a relative position, so that the end of the welding wire is located directly below the laser beam 3, that is, the laser beam is completely irradiated on the welding wire, and there is a height h1 between the end of the welding wire and the butt line plane 16, generally h1 is 0-1mm; and the second welding wire is far away from the laser beam 3, generally the second welding wire endpoint is away from the laser beam irradiation point horizontal spacing b2, generally 1-5mm, preferably 2-4mm; and its distance from the plane The height h2 of the 16 is greater than 0.5mm, preferably 1-5mm; the angle between the first welding wire and the plane 16 is α, and the angle between the second welding wire and the plane 16 is β; generally α is 15°-50 °, β is 20°-60°. During the welding process, with the continuous delivery of the first welding wire and the second welding wire and the continuous action of the laser beam, and advancing along the butt line, the welding wire and the base metal are continuously melted to form a weld; generally, the welding speed V It is 0.3-1.0m/min, preferably 0.3-0.6m/min. During the welding process, the laser energy reflected by the first welding wire and the high-temperature plasma formed when the laser beam melts the first welding wire can be fully utilized to melt the second welding wire, thereby improving the utilization rate of laser energy and increasing the welding efficiency in a single welding. The amount of seam stacking is high, which reduces the number of welding passes of thick plates and improves the manufacturing efficiency; in addition, the cooling speed of the welding seam can be reduced by the melting of the second welding wire, thereby improving the fluidity of the welding seam and avoiding the occurrence of welding defects.

In the welding process, the laser power P can be constant or variable, and the power range is generally not less than 2000W; generally 2000-10000W; the specific power value can be the size of the spot formed by irradiation with the laser beam matched. In addition, the spot shape of the laser beam can be other shapes such as rectangle, ring, etc., and the distribution of its power density can be other forms such as Gaussian type or flat top type. The angle between the central axis 31 of the laser beam and the plane where the workpiece is located is generally 90 degrees, and of course, it can also be between 80° and 100°. The laser emitting the laser beam may correspond to various types, including but not limited to solid-state lasers, direct diode lasers, photonic crystal lasers, semiconductor lasers, gas lasers, chemical lasers, excimer lasers, or free electron lasers. The laser can be a continuous laser or a pulsed laser, and its peak power is generally above 2000w, especially above 5000w. The processed metal workpiece can be metal materials including low carbon steel, stainless steel, high strength steel, aluminum alloy, copper alloy, titanium alloy and the like.

It is worth noting that the laser beam may also include a swing path around the centerline 112 with a plane perpendicular to the thickness direction of the plate during the traveling process. As shown in Figure 5, it is a zigzag swing, as shown in Figure 6, it is an arc swing, and it can also be a periodic shape such as a crescent, a sine cosine, a figure of eight and other straight lines or curves. The swing amplitude is B3, generally B3 is more than 1.0mm, preferably 1.0mm-4.0mm; it is determined according to the assembly gap B2 of the welded structure and the divergence angle of the laser beam, so that the laser beam can be irradiated to a wider range of the interface 16 as much as possible and The incidence of the laser beam is determined by not irradiating the side surface 17; and the swing frequency f of the laser beam in this direction is generally above 50 Hz, preferably above 100 Hz.

Generally, the first welding wire and the second welding wire are the same welding wire as the base material of the metal part to be welded. If the welding object is a steel workpiece, the welding wire is a steel welding wire; if the welding workpiece is an aluminum workpiece, the welding wire is an aluminum welding wire The diameter of the welding wire is generally 0.8-1.6 mm, and the first welding wire and the second welding wire can be solid welding wires with the same composition and diameter; of course, the first welding wire and the second welding wire can also be of different compositions and different diameters, for example, in a certain In some cases, the microstructure in the final weld can be adjusted by adjusting the composition difference of the two welding wires to improve the weld performance. The selection of welding wire is generally determined according to the workpiece, and the conveying of welding wire is generally completed by a wire feeder; for materials with special thickness, due to the large and narrow groove depth, a special wire feeding tube is often required. The pipe diameter is slightly larger than the wire diameter; this is relatively well understood in the art.

In the present invention, in order to fully melt the welding wire and effectively and stably melt into the molten pool, the output of the laser beam is generally ahead of the conveying of the welding wire when welding is performed, and the end of the laser beam is stopped later than the conveying of the welding wire at the end; The time difference is generally within 1 second, preferably within 0.5 seconds.

In order to effectively act the high-temperature plasma on the second welding wire during the welding process, a shielding gas device can be added between the first welding wire and the laser beam, as shown in FIG. 3 ; the shielding gas 7 is output through the shielding gas pipe 6 , blow the high-temperature plasma formed by the laser beam melting the first welding wire and the metal workpiece to the second welding wire position, so that the second welding wire is melted; 100L/min, the specific value can be determined according to the flow rate and pressure of the gas flow formed by the diameter of the pipeline and its combination; and the protective gas is generally a combination of one or more of the commonly used Ar, He, N2, and CO2. , it can also be a type such as adding O2; the specific type can be determined according to the type of material to be welded, but the general priority is Ar>He>N2>CO2, but in the welding of stainless steel materials, the preferred shielding gas is N2 .

In order to more clearly illustrate the difference between the methods of the present invention and the content of the invention, a schematic diagram is made to compare the content of the present invention with the appearance of the conventional laser wire filler welding seam. Figure 7 shows a simple schematic diagram of the welding seam after conventional laser wire filling welding; the entire welding seam is completed by multiple wire filling welding, and the filling heights of each layer are s1, s2, s3, s4, etc. When the laser energy is high, it is easy to form defects such as pores 112 and unfused sidewalls 111 inside the weld. When the laser energy input decreases, the filling amount of the welding wire decreases and the filling height of the single layer decreases, and the welding of the entire workpiece requires more Multiple passes increase production cost and manufacturing time. 8 is a schematic diagram of the welding wire melting and transition process using the method of the present invention; the laser beam 3 melts the first welding wire 4 to form droplets 41 and transitions into the molten pool, and forms high-temperature plasma 31 and the welding wire and molten pool are opposite to the laser The reflected beam energy of the beam melts the second welding wire 5 to form droplets 42 that transfer to the molten pool; compared with ordinary laser wire filling welding, the utilization rate of laser energy is high, and the melting of the droplets 42 helps to improve the formation of a single melting. The high buildup of the weld, and the post-action of the droplet 42 help to delay the cooling of the molten pool, allow sufficient time for the internal pores to drain, and increase the heat input into the molten pool, reducing the occurrence of internal non-fusion defects. FIG. 9 is a schematic cross-sectional view of a part of the welding seam formed by welding large and thick plate butt joints layer by layer using the method of the present invention.

Claims (10)

1. A laser wire filler welding method for medium and heavy plates, the method comprising the steps of: 1) Provide a pair of first metal workpiece and second metal workpiece for welding, first welding wire, second welding wire and laser beam for laser welding; process the first metal workpiece and the second metal workpiece respectively A groove with a certain blunt edge height and an opening angle, and the two workpieces have a first welding surface, a second welding surface and a welding side surface opposite up and down; the first metal workpiece and the side surface of the second metal workpiece are butted to form the to-be-welded Assemblies and butt wires; 2) The laser beam is emitted to travel along the direction of the assembly butt line, the laser beam forms an irradiation area at the butting position, the first welding wire is transported to the laser beam irradiation area at a certain speed and contacts the assembly butt line, and the second welding wire is Transported to the vicinity of the laser beam irradiation area at a certain speed; 3) advancing the laser beam, the first welding wire and the second welding wire along the butt line at a certain speed, the laser beam melts the first welding wire, the second welding wire and the butt joint of the assembly, and forms a weld after cooling and solidification; The first welding wire is irradiated by the laser beam to melt and generate high-temperature plasma, and the reflected beam and high-temperature plasma of the laser beam when irradiating the first welding wire heat the second welding wire to melt the first welding wire. It is located at the front end of the welding direction, and the second welding wire is located at the rear end of the laser beam in the welding direction; the wire feeding speed of the first welding wire is not less than 5m/min, and the wire feeding speed of the second welding wire does not exceed the feeding speed of the first welding wire; and the laser beam The irradiation power density on the first welding wire is not less than 10 ⁶ W/cm ² . 2 . A laser wire-filling welding method for medium and thick plates according to claim 1 , wherein the melting of the second welding wire is by the reflected light of the laser beam in the first welding wire and the molten pool and the high-temperature plasma formed. 3 . achieved by melting. 3. A laser wire-filling welding method for medium and thick plates according to claim 2, wherein the second welding wire end point is at a height h2 from the butt line of the assembly, and h2>0.5mm; and the end point is away from the laser beam irradiation The center has a horizontal spacing b2, generally b2≥1mm. 4. A laser wire-filling welding method for medium and thick plates according to claim 1, wherein there is also a shielding gas between the laser beam and the first welding wire, and the shielding gas will reduce the high temperature plasma generated during the welding process The body is blown in the direction of the second welding wire, and the flow rate of the shielding gas is 10-100L/min. 5. A laser wire filler welding method for medium and thick plates according to claim 1, wherein the welding process comprises that the laser beam has been irradiated before the first welding wire and the second welding wire are transported to the position The material is for a certain time, and the time does not exceed 1 second, preferably 0.5 seconds. 6. A laser wire-filling welding method for medium and thick plates according to claim 1, wherein the welding process comprises the step of irradiating the laser beam for a certain period of time after the first welding wire and the second welding wire are stopped. According to the photo, the time does not exceed 1 second, preferably 0.5 second. 7 . The laser wire-filling welding method for medium and thick plates according to claim 1 , wherein the welding speed in the welding process is 0.3-1.0 m/min. 8 . 8. A laser wire-filling welding method for medium and thick plates according to claim 1, wherein the angle between the laser beam and the first welding wire is 40°-75°, and the angle between the second welding wire and the laser beam is 40°-75°. 30°-70°. 9 . The laser wire-filling welding method for medium and thick plates according to claim 1 , wherein the wire feeding speed of the second welding wire is no more than 0.8 times that of the first welding wire. 10 . 10 . The laser wire-filling welding method for medium and thick plates according to claim 1 , wherein the first welding wire and the second welding wire are solid-core welding wires with the same composition and diameter. 11 .

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