Ultrahigh power laser and hollow tungsten electrode combined welding method based on magnetic spin control technology

Abstract

The application discloses a kind of superhigh power laser and hollow tungsten electrode composite welding methods based on magnetic rotation control technology.At present, in superhigh power laser medium plate welding, too intense heat energy conversion effect makes welding process extremely unstable, and welding problems such as porosity, spatter, forming difficult to control are prone to occur.The composition of the application includes: hollow tungsten electrode (1), superhigh power laser passes through the center hole of the hollow tungsten electrode to form coaxial composite laser beam (3), annular inductive coil or permanent magnet (2) is arranged above the welding test plate (6), the inductive coil or permanent magnet and the arc (4) at the bottom of the hollow tungsten electrode form a longitudinal magnetic field, the laser beam passes through the arc and the molten pool (5), and the longitudinal magnetic field can rotate the arc, forming a rotating arc and laser beam composite to act on the welding point area.The application is used for superhigh power laser and hollow tungsten electrode composite welding method based on magnetic rotation control technology.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ultra-high power laser-hollow tungsten electrode-longitudinal magnetic field composite welding, in particular to an ultra-high power laser and hollow tungsten electrode composite welding method based on magnetic rotation control technology. BACKGROUND

[0002] With the increasing demand for medium plate components in the fields of large ships, nuclear power, oil pipelines and boiler manufacturing in China, the existing welding technology has been difficult to meet the demand for efficient and high-quality welding technology. On the other hand, with the rapid development of high-power fiber lasers, ultra-high power laser welding technology of ten thousand watts has become one of the most important development directions of medium plate welding at present. However, the existing technology is extremely unstable during ultra-high power laser welding due to the extremely intense heat conversion effect, which easily causes welding problems such as pores, cracks, spatter and difficult to control forming. At the same time, under the interference of intense plasma plume, metal vapor and other keyhole injection, the conversion efficiency of laser power to penetration depth is much lower than that of kilowatt laser welding. These deficiencies will have a serious impact on the promotion and application of ultra-high power laser welding technology. SUMMARY

[0003] The purpose of the present application is to provide an ultra-high power laser and hollow tungsten electrode composite welding method based on magnetic rotation control technology. The method is to use ultra-high power laser to pass through the hollow tungsten electrode to form coaxial composite, and at the same time, a longitudinal magnetic field is added around the hollow tungsten electrode arc, which can rotate the arc directionally to form rotating arc and laser beam composite welding, thereby improving the welding stability and obtaining better weld forming.

[0004] The above purpose is achieved by the following technical solutions:

[0005] An ultra-high power laser and hollow tungsten electrode composite welding method based on magnetic rotation control technology, which comprises: a hollow tungsten electrode 1, an ultra-high power laser passing through the center hole of the hollow tungsten electrode to form a coaxial composite laser beam 3, an annular inductor coil or permanent magnet 2 is arranged above the welding test plate 6, the inductor coil or permanent magnet and the arc 4 at the bottom of the hollow tungsten electrode form a longitudinal magnetic field, the laser beam passes through the arc and the molten pool 5, the longitudinal magnetic field can rotate the arc directionally to form rotating arc and laser beam composite action on the welding area, the composite welding method comprises the following steps:

[0006] First, the longitudinal magnetic field is above the welding spot and around the hollow tungsten electrode current, which is realized by an inductive coil with a magnetic core or a permanent magnet, and the arc of the hollow tungsten electrode in the longitudinal magnetic field will be subjected to the Lorentz force to produce directional deflection, while being pulled by the laser plasma to form a rotating arc; in direct current welding, the hollow tungsten electrode is connected to the negative pole of the power supply, and the welding test plate is connected to the positive pole of the power supply; in alternating current welding, the switching frequency and starting time of the current must be completely consistent with the switching time of the direction of the longitudinal magnetic field, so as to realize the directional rotation of the arc;

[0007] In the process of composite welding, the rotating hollow tungsten electrode arc guides the charged particles in the plasma to move in a circular manner towards the hollow tungsten electrode and the welding test plate, rapidly disperses the plasma around, plays a role of attracting and inhibiting the plasma, and reduces the interference of the plasma on the laser beam;

[0008] The longitudinal magnetic field interacts with the arc of the hollow tungsten electrode, promotes the high-speed rotation of the charged particles in the hollow tungsten electrode arc under the action of the Lorentz force, makes the arc expand outward, improves the spreading property of the welding bead and the fluidity of the molten pool, increases the amount of liquid metal in the area around the opening of the laser spoon hole, reduces the metal vapor in the super-high-power laser spoon hole, and promotes the initial kinetic energy and impulse of the liquid metal to form a metal liquid column, thereby inhibiting the formation of the metal liquid column and reducing the probability of splashing of the large-size metal liquid column.

[0009] The rotating arc agitates the molten pool around the spoon hole to produce directional rotational flow or vortex-like rotational flow, and under the action of centrifugal force, the opening diameter of the spoon hole is expanded, the molten pool around the spoon hole produces directional rotational flow, the dendritic crystals are broken into equiaxed crystals during solidification, and the isotropy of the grains is improved and the segregation effect is reduced.

[0010] The super-high-power laser and hollow tungsten electrode composite welding method based on the magnetic rotation control technology, when the laser beam is combined with the hollow tungsten electrode arc under the action of the longitudinal magnetic field, the super-high-power laser beam is combined with the whole clock-shaped directional rotating arc when the welding current is above 300A, and the super-high-power laser beam is combined with the local directional deflected arc when the welding current is below 300A.

[0011] The super-high-power laser and hollow tungsten electrode composite welding method based on the magnetic rotation control technology, the magnetic induction intensity of the longitudinal magnetic field ranges from 0.05 to 2 Tesla, the average current output of the hollow tungsten electrode argon arc welding ranges from 100 to 630A, the inner diameter of the hollow tungsten electrode is 3 to 6mm, the outer diameter is 6 to 10mm, and the power of the laser beam ranges from 0 to 30kW.

[0012] Beneficial effects:

[0013] 1. This invention is a composite welding method for ultra-high power laser and hollow tungsten electrode based on magnetic spin control technology. The method uses an ultra-high power laser to pass through a hollow tungsten electrode to form a coaxial composite, which guides charged particles in the plasma to accelerate in a circular motion towards the hollow tungsten electrode and the workpiece, while rapidly dispersing the plasma in all directions. This attracts and suppresses the plasma, thereby reducing plasma interference with the laser beam and improving welding stability. Simultaneously, it increases the energy density of the laser entering the keyhole, increasing the weld penetration depth.

[0014] 2. This invention employs a longitudinal magnetic field applied around the hollow tungsten electrode current. This causes the charged particles in the hollow tungsten electrode arc to rotate at high speed under the action of the Lorentz force, causing the arc to expand outward and spread. This improves the spreadability of the weld bead and the fluidity of the molten pool. At the same time, it increases the amount of liquid metal in the area around the laser keyhole opening, reducing the initial kinetic energy and impulse of the liquid metal column formed by the metal vapor in the ultra-high power laser keyhole. This, in turn, helps to suppress the formation of the liquid metal column, reduce the probability of spatter from the formation of large-sized liquid metal columns, improve welding stability, and obtain better weld formation.

[0015] 3. The directional rotation design of the hollow tungsten electrode arc of this invention can agitate the molten pool to generate directional rotating flow around the keyhole, and even generate vortex-like rotating flow. Under the action of centrifugal force, the opening diameter of the keyhole is enlarged, the release speed of the injected material in the keyhole is increased, and the interaction time between the injected material and the laser beam is reduced, thereby improving the energy conversion efficiency of the laser beam and further increasing the penetration depth of the single-pass weld. At the same time, the directional rotation of the molten metal around the keyhole can also significantly improve the stability of the keyhole, which has a good effect on reducing porosity inside the weld, improving the stability of the welding process, and reducing spatter.

[0016] 4. The present invention creates a directional rotating flow effect around the keyhole in the molten pool, which can break the dendrites into equiaxed crystals during solidification, improve the isotropy of the grains and reduce segregation, thereby achieving the optimization of microstructure properties such as grain refinement, improved microstructure uniformity, reduced crystallization cracks, and improved joint mechanical properties and fatigue resistance. Attached image description:

[0017] Appendix Figure 1 This is a schematic diagram of the structure of the present invention.

[0018] Among them: 1. Hollow tungsten electrode, 2. Inductor coil or permanent magnet, 3. Laser beam, 4. Electric arc, 5. Molten pool, 6. Welding test plate. Detailed implementation method:

[0019] Example 1:

[0020] The method comprises a hollow tungsten electrode (1), a super high power laser beam (3) passing through the center hole of the hollow tungsten electrode to form a coaxial composite laser beam, a ring-shaped inductive coil or permanent magnet (2) arranged above the welding test plate (6), the inductive coil or permanent magnet and the arc (4) at the bottom of the hollow tungsten electrode form a longitudinal magnetic field, the laser beam passes through the arc and the molten pool (5), the longitudinal magnetic field can direct the rotating arc, and the rotating arc and the laser beam composite cooperatively act on the welding point area, and the inside of the hollow tungsten electrode is connected with a trace amount of protective gas to prevent the negative pressure effect of the discharge area of the hollow tungsten electrode from causing the other end of the hollow tungsten electrode to directly suck in air and conduct to the welding point area to affect the welding quality.

[0021] The composite welding method comprises the following steps:

[0022] First, the longitudinal magnetic field is arranged directly above the welding point and around the current of the hollow tungsten electrode, and is realized by an inductive coil with a magnetic core or a permanent magnet, the arc of the hollow tungsten electrode is deflected in the longitudinal magnetic field by the Lorentz force, and is simultaneously pulled by the laser plasma to form a rotating arc; in direct current welding, the hollow tungsten electrode is connected to the negative pole of the power supply, and the welding test plate is connected to the positive pole of the power supply; in alternating current welding, the switching frequency and starting time of the current are completely consistent with the switching time of the direction of the longitudinal magnetic field, so that the rotating arc is realized.

[0023] In the composite welding process, the rotating arc of the hollow tungsten electrode leads the charged particles in the plasma to accelerate in a circular direction towards the hollow tungsten electrode and the welding test plate, rapidly disperses the plasma in all directions, plays a role of attracting and inhibiting the plasma, reduces the interference of the plasma on the laser beam, improves the welding stability, increases the energy density of the laser entering the keyhole, and improves the weld penetration depth.

[0024] The longitudinal magnetic field interacts with the arc of the hollow tungsten electrode, promotes the high-speed rotation of the charged particles in the arc of the hollow tungsten electrode by the Lorentz force, makes the arc expand outward, improves the weld spreading property and the molten pool fluidity, increases the amount of liquid metal in the area around the laser keyhole, reduces the metal vapor in the super high power laser keyhole, and promotes the initial kinetic energy and impulse of the liquid metal column, inhibits the formation of the liquid metal column, reduces the probability of the formation of the large-size liquid metal column and the splashing, improves the welding stability, and has the effect of obtaining a good weld formation.

[0025] The rotational electric arc agitates the molten pool to generate a directional rotational flow or a vortex-like rotational flow around the spoon hole, under the action of centrifugal force, the opening diameter of the spoon hole is enlarged, the release speed of the ejected material in the spoon hole is increased, the interaction time of the ejected material and the laser beam is reduced, and the conversion efficiency of the laser beam energy is improved, which can further increase the single-pass weld penetration; at the same time, the directional rotation of the molten metal around the spoon hole can also greatly improve the stability of the spoon hole, which has good effects on reducing the internal porosity of the weld, improving the stability of the welding process, and reducing spatter.

[0026] The molten pool generates a directional rotational flow around the spoon hole, which breaks the dendritic crystals into equiaxed crystals during the solidification process, improves the isotropy of the grains and reduces the segregation effect, and further realizes the effects of refining the grains, improving the uniformity of the structure, reducing the crystallization cracks, improving the mechanical properties and fatigue resistance of the joint, and optimizing the structure performance.

[0027] Embodiment 2:

[0028] According to the super-high-power laser and hollow tungsten electrode composite welding method based on the magnetic rotation control technology in Embodiment 1, when the laser beam is combined with the hollow tungsten electrode arc under the action of the longitudinal magnetic field, the super-high-power laser beam is combined with the whole clock-like directional rotating arc when the welding current is above 300 A, and the super-high-power laser beam is combined with the local directional deflected arc when the welding current is below 300 A; due to the difference between the two composite forms, there will be certain differences in the magnetic rotation control process parameters.

[0029] Embodiment 3:

[0030] According to the super-high-power laser and hollow tungsten electrode composite welding method based on the magnetic rotation control technology in Embodiment 2, the magnetic induction intensity of the longitudinal magnetic field ranges from 0.05 to 2 Tesla, the average current output of the hollow tungsten electrode argon arc welding ranges from 100 to 630 A, and the current range can be appropriately expanded according to the special needs of different welding materials and processes, the inner diameter of the hollow tungsten electrode is 3-6 mm, the outer diameter is 6-10 mm, and the power of the laser beam ranges from 0 to 30 kW.

[0031] If the longitudinal magnetic field is realized by a magnetic core inductor coil, the magnetic field intensity parameter can be gradually adjusted according to the actual following situation of the metal molten pool to the rotational electric arc during the starting of the composite welding, the directional rotation speed of the molten pool is quickly and stably improved, and the purpose of stable welding is achieved. The application range is also suitable for laser welding processing below the power of ten thousand watts.

Claims

1. A method for ultra-high power laser and hollow tungsten electrode hybrid welding based on magnetic spin control technology, the method comprising: The application relates to a single hollow tungsten electrode (1) characterized in that: An ultra-high-power laser beam (3) passes through the center hole of the hollow tungsten electrode to form a coaxial composite laser beam, a ring-shaped inductive coil or a permanent magnet (2) is arranged above a welding test plate (6), the inductive coil or the permanent magnet forms a longitudinal magnetic field with an arc (4) at the bottom of the hollow tungsten electrode, the laser beam passes through the arc and a molten pool (5), the longitudinal magnetic field can direct the rotating arc, and the rotating arc and the laser beam are combined to act on a welding point area, and the composite welding method comprises the following steps: First, the longitudinal magnetic field is above the welding point and surrounds the current of the hollow tungsten electrode, and is realized by an inductive coil with a magnetic core or a permanent magnet; the arc of the hollow tungsten electrode is in the longitudinal magnetic field and is subjected to Lorentz force to produce directional deflection and is subjected to laser plasma traction to form a rotating arc; in direct current welding, the hollow tungsten electrode is connected to the negative pole of a power supply, and the welding test plate is connected to the positive pole of the power supply; in alternating current welding, the switching frequency and starting time of the current are completely consistent with the switching time of the direction of the longitudinal magnetic field, so that the rotating arc is realized. In the composite welding process, the rotating arc of the hollow tungsten electrode leads to the circular acceleration of the charged particles in the plasma towards the hollow tungsten electrode and the welding test plate, rapidly disperses the plasma in all directions, and plays a role of attracting and inhibiting the plasma, thereby reducing the interference of the plasma on the laser beam. The longitudinal magnetic field interacts with the arc of the hollow tungsten electrode, promotes the high-speed rotation of the charged particles in the arc of the hollow tungsten electrode under the action of Lorentz force, makes the arc expand outward, improves the spreading property of the welding bead and the fluidity of the molten pool, increases the amount of liquid metal in the area around the laser keyhole, reduces the metal vapor in the ultra-high-power laser keyhole, and promotes the initial kinetic energy and impulse of the liquid metal to form a metal liquid column, thereby inhibiting the formation of the metal liquid column and reducing the probability of splashing of the large-size metal liquid column. The rotating arc agitates the molten pool to produce directional rotational flow or vortex-like rotational flow around the keyhole, the opening diameter of the keyhole is expanded under the action of centrifugal force, the molten pool produces directional rotational flow around the keyhole, dendritic crystals are broken into equiaxed crystals in the solidification process, and the isotropy of the crystal grains is improved and the segregation effect is reduced.

2. The method according to claim 1, wherein the method is a magnetic field controlled hybrid welding method of ultra-high power laser and hollow tungsten electrode. The laser beam is combined with the whole clock-shaped directional rotating arc under the action of the longitudinal magnetic field when the welding current is above 300 A, and the laser beam is combined with the locally directional deflected arc when the welding current is below 300 A.

3. The method according to claim 1, wherein the method is characterized in that: The magnetic induction intensity of the longitudinal magnetic field is 0.05-2 Tesla, the average current output of the hollow tungsten electrode argon arc welding is 100-630 A, the inner diameter of the hollow tungsten electrode is 3-6 mm, the outer diameter of the hollow tungsten electrode is 6-10 mm, and the power of the laser beam is 0-30 kW.

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