CN115351420A - A kind of laser modification welding method - Google Patents

Abstract

The application discloses a laser modification welding method, relates to the field of laser welding, and aims to solve the technical problem that the existing modification welding method cannot eliminate the defect of a deeper pore of a welding line. The laser modification welding method comprises the following steps: under the protection of inert gas, cleaning after carrying out first laser modification welding on a metal material to be welded by adopting a laser and a laser welding head to obtain an initial welding line I; when the first laser modification welding is carried out, the laser welding head does not start the scanning function of the two-dimensional galvanometer; obtaining a second laser modification welding parameter based on the initial welding seam I; performing secondary laser modification welding on the initial welding seam I by using a laser and a laser welding head under the protection of inert gas based on the secondary laser modification welding parameters to obtain a modified welding seam II; and when the laser modification welding is carried out for the second time, the laser welding head starts the scanning function of the two-dimensional galvanometer.

Description

A kind of laser modification welding method

technical field

The present application relates to the field of laser welding, in particular to a laser modification welding method.

Background technique

Laser welding has the advantages of high energy density, large weld depth ratio, small welding deformation, high efficiency, and wide material adaptability. It is widely used in the welding of metal structural parts in aviation, aerospace, nuclear power, rail transit and other fields. With the development of high-power lasers, the advantages of large penetration and high-speed laser welding in terms of efficiency, deformation and precision control are more prominent. High-power laser deep penetration welding mainly depends on the establishment of keyholes under the recoil force of metal evaporation, and the plume and violent oscillation of the molten pool generated by metal evaporation will cause defects such as rough surface formation, undercuts, undercuts, and pores of the laser welding surface. , has seriously affected the welding quality and the safety and reliability of the structure. Therefore, it is of great engineering significance to improve the quality of laser welds by using cosmetic welding.

However, most of the current modification welding methods are thermal conduction welding methods, and the depth of the modification layer is limited, which cannot eliminate the pores defects in the deeper layer of the weld.

Contents of the invention

The main purpose of this application is to provide a laser modification welding method, which aims to solve the technical problem that the existing modification welding method cannot eliminate the gas hole defects in the deeper layer of the weld.

In order to solve the above technical problems, the present application proposes: a laser modification welding method, comprising the following steps:

Under the protection of an inert gas, use a laser and a laser welding head to carry out the first laser decoration welding on the metal material to be welded, and then clean up to obtain the initial weld I; during the first laser decoration welding, the laser welding head is not Turn on the 2D galvanometer scanning function;

Based on the initial weld I, obtain the second laser modification welding parameters;

Based on the parameters of the second laser modification welding, under the protection of an inert gas, a laser and a laser welding head are used to perform a second laser modification welding on the initial weld I to obtain a modification weld II; the second During laser modification welding, the laser welding head turns on the scanning function of the two-dimensional galvanometer.

As some optional implementations of the present application, before obtaining the second laser modification welding parameters based on the initial weld I, it also includes:

The appearance forming and internal quality inspection are carried out on the initial weld I, and the defects with undercut or oversize are filled with metal filler sheets of the same material as the metal material to be welded.

As some optional implementation manners of the present application, the metal material to be welded includes: at least one of carbon steel, stainless steel and aluminum alloy.

As some optional implementation manners of the present application, the thickness of the metal material to be welded is 3-5 mm.

As some optional implementations of this application, the parameters of the first laser modification welding include: the scanning function of the two-dimensional galvanometer is not turned on, the laser focal length is 480mm, the diameter of the focal spot is 0.36mm, the laser output power is 4kW, and the welding speed It is 1.2m/min, and the protective gas adopts high-purity argon with a purity of 99.999%.

As some optional implementations of this application, the parameters of the second laser modification welding include: turn on the scanning function of the two-dimensional galvanometer, the laser focal length is 480 mm, the diameter of the focal spot is 0.36 mm, the scanning path is a circle with a diameter of 4 mm, and the scanning The frequency is 50Hz, the laser output power is 4kW, and the welding speed of cosmetic welding is 1.2m/min.

As some optional embodiments of the present application, the inert gas includes at least one of helium, argon and nitrogen; the purity of the inert gas is ≥99%.

As some optional implementation manners of the present application, the laser includes at least one of a fiber laser, a disk laser, and a semiconductor laser.

As some optional implementation manners of the present application, the welding method includes at least one of lap joint and plug joint.

As some optional implementation manners of the present application, the welding position includes at least one of vertical welding, horizontal welding and overhead welding.

Existing modification welding methods are usually TIG remelting modification welding, electron beam modification welding, laser modification welding and so on. TIG remelting modified welding has shallow penetration, low efficiency, and large heat input, which has a great impact on joint deformation and tissue properties; electron beam modified welding requires a vacuum environment, poor accessibility, and relatively complicated process. The existing laser modification welding mainly adopts the method of increasing the spot size by defocusing the beam and changing the energy distribution of the beam by the integrating mirror, reducing the energy density of the laser, so that the laser welding is transformed from the deep penetration welding method to the heat conduction welding method, and the penetration depth becomes smaller, The weld width becomes larger, which reduces the undercut of the weld surface and the porosity defects near the surface, and improves the quality of weld formation. However, since these two laser modification methods are heat conduction welding methods, the depth of the modification layer is limited, and the pores defects in the deeper layer of the weld cannot be eliminated. Therefore, the present application proposes a laser modification welding method, that is, under the protection of an inert gas, use a laser and a laser welding head to perform laser modification welding on the metal material to be welded for the first time, and then clean up to obtain the initial weld I; During the first laser modification welding, the laser welding head did not turn on the two-dimensional galvanometer scanning function; based on the initial weld I, the second laser modification welding parameters were obtained; based on the second laser modification welding parameters, Under the protection of an inert gas, a laser and a laser welding head are used to perform a second laser modification welding on the initial weld I to obtain a modification welding seam II; during the second laser modification welding, the laser welding head Turn on the 2D galvanometer scanning function. It can be seen that under the protection of inert gas, this application conducts modification welding on the metal to be welded twice. The first time the laser modification welding is performed without turning on the two-dimensional galvanometer scanning function of the laser welding head, and the second time the laser modification welding is performed. The two-dimensional galvanometer scanning function of the laser welding head is turned on during cosmetic welding. Based on the two-dimensional galvanometer scanning method, the beam trajectory and action position are changed to perform cosmetic welding, and the surface and internal defects are deeply repaired to improve the quality of the weld; and The scanning of the two-dimensional galvanometer will not change the energy distribution of the beam itself, so that the modified welding can be performed in the deep penetration welding mode, and compared with the prior art that uses the heat conduction method of beam defocusing and integrating mirror shaping to modify the welding method, so that Finishing layers are deeper, minimizing deeper internal weld defects.

Description of drawings

Fig. 1 is a schematic flow chart of the steps of the laser modification welding method described in the embodiment of the present application;

Fig. 2 is a schematic diagram of the principle of the laser modification welding method described in the embodiment of the present application;

Among them, 1-collimating mirror; 2-X-axis galvanometer; 3-Y-axis galvanometer; 4-laser beam; 5-focusing mirror; 6-initial weld I; 7-modified weld II; 8-to-be-welded metallic material.

Detailed ways

It should be understood that the specific embodiments described here are only used to explain the present application, and are not intended to limit the present application.

Laser welding has the advantages of high energy density, large weld depth ratio, small welding deformation, high efficiency, and wide material adaptability. It is widely used in the welding of metal structural parts in aviation, aerospace, nuclear power, rail transit and other fields. With the development of high-power lasers, the advantages of large penetration and high-speed laser welding in terms of efficiency, deformation and precision control are more prominent. High-power laser deep penetration welding mainly depends on the establishment of keyholes under the recoil force of metal evaporation, and the plume and violent oscillation of the molten pool generated by metal evaporation will cause defects such as rough surface formation, undercuts, undercuts, and pores of the laser welding surface. , has seriously affected the welding quality and the safety and reliability of the structure. Therefore, it is of great engineering significance to improve the quality of laser welds by using cosmetic welding.

However, most of the current modification welding methods are thermal conduction welding methods, and the depth of the modification layer is limited, which cannot eliminate the pores defects in the deeper layer of the weld. For example, the existing modification welding methods are usually TIG remelting modification welding, electron beam modification welding, laser modification welding and the like. TIG remelting modified welding has shallow penetration, low efficiency, and large heat input, which has a great impact on joint deformation and tissue properties; electron beam modified welding requires a vacuum environment, poor accessibility, and relatively complicated process. The existing laser modification welding mainly adopts the method of increasing the spot size by defocusing the beam and changing the energy distribution of the beam by the integrating mirror, reducing the energy density of the laser, so that the laser welding is transformed from the deep penetration welding method to the heat conduction welding method, and the penetration depth becomes smaller, The weld width becomes larger, the undercut amount on the weld surface and the air hole defects near the surface are reduced, and the weld forming quality is improved. However, since these two laser modification methods are heat conduction welding methods, the depth of the modification layer is limited, and the pores defects in the deeper layer of the weld cannot be eliminated.

Based on this, the main purpose of this application is to provide a laser modification welding method, which aims to solve the technical problem that the existing modification welding method cannot eliminate the gas hole defects in the deeper layer of the weld.

As shown in Figure 1, a laser modification welding method provided in the embodiment of the present application includes the following steps:

S10. Under the protection of an inert gas, use a laser and a laser welding head to perform the first laser modification welding on the metal material to be welded, and then clean up to obtain an initial weld I; during the first laser modification welding, the laser welding The 2D galvanometer scanning function is not enabled on the head.

In a specific application, in order to achieve the expected effect of the technical solution described in the embodiment of the application, the technical solution of the application is specifically defined, that is, the laser includes at least one of fiber lasers, disk lasers and semiconductor lasers, or other lasers; The laser welding head is a laser processing head with a two-dimensional galvanometer scanning function; the metal to be welded includes at least one metal material in carbon steel, stainless steel and aluminum alloy; the thickness of the metal material to be welded is 3 to 5mm The welding method includes at least one of lap joint and plug joint; the welding position includes at least one of vertical welding, horizontal welding and overhead welding; the inert gas includes at least one of helium, argon and nitrogen ; The purity of the inert gas is ≥99%.

In a specific application, after the first laser modification and welding of the metal material to be welded by using the laser and the laser welding head, the cleaning method includes mechanical grinding, chemical cleaning or laser cleaning and other surface cleaning methods. The main purpose is to clear the initial Defects such as oxide film and spatter on the surface of weld I.

In specific applications, when the laser welding process parameters are not properly selected, the welding process will become unstable, and the welded joints are prone to defects such as pores and undercuts, which are difficult to meet the actual application requirements in the field of aerospace precision manufacturing. Therefore, the parameters of the first laser modification welding described in this application include: the scanning function of the two-dimensional galvanometer is not turned on, the laser focal length is 480mm, the diameter of the focal spot is 0.36mm, the laser output power is 4kW, and the welding speed is 1.2m/min. The protective gas adopts high-purity argon with a purity of 99.999%.

In a specific application, in order to minimize deeper internal welding defects, before obtaining the second laser modification welding parameters based on the initial weld I, it also includes:

The appearance forming and internal quality inspection are carried out on the initial weld I, and the defects with undercut or oversize are filled with metal filler sheets of the same material as the metal material to be welded.

S20. Based on the initial weld I, obtain welding parameters for a second laser modification.

In specific applications, when the laser welding process parameters are not properly selected, the welding process will become unstable, and the welded joints are prone to defects such as pores and undercuts, which are difficult to meet the actual application requirements in the field of aerospace precision manufacturing. Therefore, the parameters of the second laser modification welding described in this application include: turn on the scanning function of the two-dimensional galvanometer, the laser focal length is 480 mm, the diameter of the focal spot is 0.36 mm, the scanning path is a circle with a diameter of 4 mm, the scanning frequency is 50 Hz, and the laser output The power is 4kW, and the welding speed of cosmetic welding is 1.2m/min.

In a specific application, based on the defect characteristics of the initial weld I, the parameters of the second laser modification welding are set, such as judging whether the initial weld I has typical defects such as undercut, collapse or pores.

S30. Based on the parameters of the second laser modification welding, under the protection of an inert gas, use a laser and a laser welding head to perform a second laser modification welding on the initial weld I to obtain a modification weld II; During the second laser modification welding, the laser welding head turns on the scanning function of the two-dimensional galvanometer.

In a specific application, in order to achieve the expected effect of the technical solution described in the embodiment of the application, the technical solution of the application is specifically defined, that is, the laser includes at least one of fiber lasers, disk lasers and semiconductor lasers, or other lasers; The laser welding head is a laser processing head with a two-dimensional galvanometer scanning function; the metal to be welded includes at least one metal material in carbon steel, stainless steel and aluminum alloy; the thickness of the metal material to be welded is 3 to 5mm The welding method includes at least one of lap joint and plug joint; the welding position includes at least one of vertical welding, horizontal welding and overhead welding; the inert gas includes at least one of helium, argon and nitrogen ; The purity of the inert gas is ≥99%.

In a specific application, the difference between the first laser modification welding and the second laser modification welding is that the first laser modification welding does not turn on the galvanometer scanning function, while the second laser modification welding The galvanometer scan function is turned on. In this embodiment, the laser welding head used in the first laser decoration welding and the laser welding head used in the second laser decoration welding are completed by the same laser welding head, and there is no need to replace hardware. In the prior art, the method of regulating the beam energy through the integrator mirror needs to replace and adjust the optical path hardware of the laser welding torch, and the process flow of the present application is simpler.

It can be seen that, as shown in Figure 2, the laser galvanometer scanning welding is a new type of laser welding technology. The laser beam is incident on the two mirrors of the scanning galvanometer in pulse or continuous mode, and passes through the X and Y directions. The motor on the machine drives the mirror to deflect, realizing the rapid movement of the beam in a specific plane, and finally focusing on the surface of the workpiece through the focusing lens to form a specific scanning track. According to the principle of laser galvanometer scanning welding technology, when the laser beam swings with a certain scanning trajectory, the range of action of the laser spot is expanded compared with that of non-scanning laser welding, which can improve the gap adaptability of the joint and reduce the operator's pre-weld assembly time. Accuracy requirements, improve production efficiency. During the swinging process of the laser beam, the position of the heat source is constantly changing, which affects the temperature distribution and heat flow direction in the welding pool, resulting in the constant change of the maximum heat dissipation direction in the pool. Since the preferred growth direction of columnar crystals is opposite to the maximum heat dissipation direction, the growth of columnar crystals that are preferentially grown at the previous moment may be inhibited at the next moment, thus destroying the orientation of columnar crystal growth in the laser welding head and improving the uniformity of the structure . In addition, due to the reciprocating swing of the laser beam on the weld seam, on the one hand, the local weld seam is remelted, which prolongs the existence time of the liquid molten pool; The stirring effect promotes the convection of liquid metal in the molten pool, and both are beneficial to eliminate the pores in the weld. However, the scanning trajectory of the laser galvanometer is a two-dimensional plane, which cannot effectively intervene in the three-dimensional solidification and crystallization process of the liquid metal in the molten pool. The overall effect is limited.

Compared with the prior art, under the protection of inert gas, this application conducts modification welding on the metal to be welded twice. The first time the laser welding head’s two-dimensional galvanometer scanning function was not turned on during the laser modification welding, and the second time When performing laser modification welding, the two-dimensional galvanometer scanning function of the laser welding head is turned on. Based on the two-dimensional galvanometer scanning method, the beam trajectory and action position are changed to perform modification welding, and the surface and internal defects are deeply repaired, and the weld seam is improved. Quality; and the two-dimensional galvanometer scanning will not change the energy distribution of the beam itself, so that the modified welding can be performed in the deep penetration welding mode, and compared with the prior art that uses beam defocus and integral mirror shaping heat conduction modified welding method, making the finishing layer deeper, minimizing deeper internal welding defects.

Below in conjunction with specific embodiment the method described in the application is described in more detail:

Example 1

Use a 10kW fiber laser and a Wobble-60 laser welding head with a two-dimensional galvanometer scanning function to weld a 4mm thick TC4 titanium alloy metal butt joint to be welded. The joint is a butt joint, and the laser focal length is 480mm. The spot diameter is 0.36mm, the laser output power is 4kW, the welding speed is 1.2m/min, and the shielding gas is high-purity argon gas with a purity of 99.999%. Whether there are typical defects such as undercut, collapse, and air holes.

Use mechanical grinding to remove the oxide film on the surface of the initial weld, and determine the location of over-standard defects such as undercut, collapse, and pores. For places where undercut or oversize can be prefabricated, metal filler sheets of the same quality as the base material can be prefabricated. The filler sheet is TC4 titanium alloy sheet with a thickness of 1mm, 2mm, and 3mm, and the initial weld I is obtained.

According to the defect characteristics of the initial weld I, set parameters such as galvanometer scanning parameters, scanning path, and laser power. The scanning path of this embodiment is a circle with a diameter of 4 mm, and the scanning frequency is 50 Hz. The same laser power, ie 4kW.

Turn on the galvanometer scanning function of the laser welding head, and perform laser modification welding on the initial weld I. The welding speed of the modification welding is 1.2m/min, and the shielding gas uses high-purity argon with a purity of 99.999%. Finally, the appearance forming and internal quality inspection of the weld are carried out, and the changes of undercut, undercut and porosity defects before and after modification welding are compared. The shape size of the weld before and after the modified welding was compared through the optical microscope photos of the welding section, and the change of the internal porosity defects of the weld was compared through X-ray flaw detection.

The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structures or equivalent process transformations made by using the description of the application and the accompanying drawings are directly or indirectly used in other related technical fields. , are all included in the patent protection scope of the present application in the same way.

Claims (10)

1. A laser trimming welding method is characterized by comprising the following steps:

under the protection of inert gas, cleaning after carrying out first laser modification welding on a metal material to be welded by adopting a laser and a laser welding head to obtain an initial welding line I; when the first laser modification welding is carried out, the laser welding head does not start the scanning function of the two-dimensional galvanometer;

obtaining a second laser modification welding parameter based on the initial welding seam I;

performing secondary laser modification welding on the initial welding seam I by using a laser and a laser welding head under the protection of inert gas based on the secondary laser modification welding parameters to obtain a modified welding seam II; and when the second laser modification welding is carried out, the laser welding head starts the scanning function of the two-dimensional galvanometer.

2. The laser modified welding method of claim 1, further comprising, prior to said obtaining a second laser modified welding parameter based on said initial weld I:

and performing appearance forming and internal quality detection on the initial welding seam I, and filling metal filling sheets which are used for the metal materials to be welded and have the same material at the defect positions with undercut or overlarge lower beds.

3. The laser modified welding method of claim 1, wherein the metal material to be welded comprises: at least one of carbon steel, stainless steel and aluminum alloy.

4. The laser modified welding method of claim 2, wherein the thickness of the metal material to be welded is 3 to 5mm.

5. The laser modified welding method of claim 1, wherein the parameters of the first laser modified weld comprise: the scanning function of the two-dimensional galvanometer is not started, the focal length of the laser is 480mm, the diameter of a focal spot is 0.36mm, the output power of the laser is 4kW, the welding speed is 1.2m/min, and high-purity argon with the purity of 99.999 percent is adopted as the shielding gas.

6. The laser modified welding method of claim 1 wherein the parameters of the second laser modified weld comprise: starting a scanning function of a two-dimensional galvanometer, wherein the focal length of laser is 480mm, the diameter of a focal spot is 0.36mm, a scanning path is a circle with the diameter of 4mm, the scanning frequency is 50Hz, the output power of the laser is 4kW, and the welding speed of the modified welding is 1.2m/min.

7. The laser modified welding method of claim 1, wherein the inert gas comprises at least one of helium, argon, and nitrogen; the purity of the inert gas is more than or equal to 99 percent.

8. The laser modified welding method of claim 1, wherein the laser comprises at least one of a fiber laser, a disk laser, and a semiconductor laser.

9. The laser modified welding method of claim 1, wherein the welding mode comprises at least one of overlapping and splicing.

10. The laser modified welding method of claim 1, wherein the welding location comprises at least one of a vertical weld, a transverse weld, and an overhead weld.

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