Thick-wall dissimilar metal TIG (Tungsten Inert Gas) narrow-gap welding device and method based on magnetic control arc

Abstract

The invention discloses a thick-wall dissimilar metal TIG narrow gap welding device and method based on magnetic control electric arcs, and relates to the technical field of dissimilar welding. According to the thick-wall dissimilar metal TIG narrow gap welding device, an excitation iron core and a TIG welding gun are both fixedly connected with a welding gun supporting body; an excitation coil is spirally wound on the excitation iron core; the excitation coil is electrically connected with a pulse excitation power supply to generate an alternating magnetic field; the excitation iron core and the magnetic shoe form a magnetic circuit conduction structure, and an alternating magnetic field is conducted to a welding area; a narrow-gap groove is formed by combining a non-magnetic base material and a ferromagnetic base material in a welding area; the alternating magnetic field acts on an electric arc space in the narrow gap groove; the cooling device is fixed to the magnetic shoe in an interference fit mode and cools the magnetic shoe. Asymmetric pulse excitation is applied to the magnet exciting coil, a symmetric magnetic field is formed in an electric arc area in the non-magnetic / ferromagnetic narrow-gap groove, and it is ensured that the electric arc generates stable and controllable periodic swing under the action of the magnetic field.

Description

Technical Field

[0001] The present invention relates to the technical field of dissimilar welding, and more particularly to a thick-wall dissimilar metal TIG narrow gap welding device and method based on a magnetron arc. Background Art

[0002] At present, magnetic control swing arc welding technology can reconstruct the arc energy distribution and increase the heat input of the narrow gap weld side wall by regulating the arc morphology and molten pool behavior through the magnetic field, thereby effectively suppressing the lack of fusion defects. At the same time, the temperature field and alloy element distribution are uniformed by the molten pool stirring effect, and it has been widely used in narrow gap welding of the same material. However, for the welding of thick-walled composite components of non-magnetic / ferromagnetic dissimilar steels (such as 304 austenitic stainless steel and Q235b carbon steel), due to the significant difference in the magnetic physical properties of the parent materials, the traditional TIG welding process is easily disturbed by the magnetic blow effect, resulting in a decrease in the stability of the arc symmetrical swing and an imbalance in the molten pool flow, which in turn causes lack of fusion defects and deterioration of joint performance. In addition, the sensitivity of ferromagnetic materials to magnetic field distribution makes it difficult for existing magnetic control swing arc technology to achieve uniform and controllable arc swing and magnetic field coupling in the narrow gap groove of dissimilar steels. Therefore, how to design a magnetic control arc swing method suitable for narrow gap welding of non-magnetic / ferromagnetic dissimilar steels to overcome the magnetic blow effect and coordinate the magnetic field response differences between dissimilar materials is a problem that technicians in this field urgently need to solve. Summary of the Invention

[0003] In view of this, the present invention provides a thick-walled dissimilar metal TIG narrow gap welding device and method based on magnetic controlled arc, which overcomes the above-mentioned defects.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A thick-walled dissimilar metal TIG narrow gap welding device based on a magnetic control arc comprises: an excitation coil, a pulse excitation power supply, an excitation core, a magnetic shoe, a welding gun support, a TIG welding gun and a cooling device; the excitation core and the TIG welding gun are both fixedly connected to the welding gun support; the excitation coil is spirally wound on the excitation core; the excitation coil is electrically connected to the pulse excitation power supply to generate an alternating magnetic field; the excitation core is fixedly connected to the magnetic shoe to form a magnetic circuit conduction structure to conduct the alternating magnetic field to the welding area; the welding area uses a combination of non-magnetic base material and ferromagnetic base material to form a narrow gap groove; the alternating magnetic field acts on the arc space within the narrow gap groove; the cooling device is fixed to the magnetic shoe by an interference fit to cool the magnetic shoe.

[0006] Furthermore, the magnetic shoes adopt a double magnetic shoe structure, and the magnetic shoe spacing is 18-25mm.

[0007] Furthermore, the magnetic shoe is made of soft magnetic material electrical iron DT4C.

[0008] Furthermore, the tungsten pole of the TIG welding gun is fixed on the central symmetric axis of the magnetic circuit.

[0009] Furthermore, the magnetic circuit is a gap-containing magnetic circuit with a height of 220-280 mm and a width of 100-180 mm.

[0010] Furthermore, the pulse excitation power supply outputs an asymmetric alternating excitation current, wherein the arc corresponding to the maximum amplitude swings toward the non-magnetic base material side, and the arc corresponding to the minimum amplitude swings toward the ferromagnetic base material side.

[0011] Furthermore, a welding power source is included, which is connected to the TIG welding gun and is used to provide the current required for the welding arc.

[0012] A method for thick-walled dissimilar metal TIG narrow gap welding based on a magnetron arc, the specific steps are as follows:

[0013] generating an alternating magnetic field based on a magnetic generating device;

[0014] The alternating magnetic field is focused on the arc space of the narrow gap groove through the magnetic circuit conduction structure formed by the excitation core and the magnetic shoe;

[0015] A TIG welding gun is used to ignite an arc in the arc space within the narrow gap groove, and at the same time, the arc current is adjusted by a welding power supply so that the arc produces periodic swings under the action of the alternating magnetic field and melts the welding wire to fill the narrow gap groove; the narrow gap groove is formed by a combination of a non-magnetic base material and a ferromagnetic base material.

[0016] It can be seen from the above technical solutions that, compared with the prior art, the present invention provides a thick-walled dissimilar metal TIG narrow gap welding device and method based on a magnetron arc, which has the following beneficial effects:

[0017] 1. The magnetic field strength can be enhanced through the design of a small gap-containing magnetic circuit (combination of the excitation core and the magnetic shoe). Pulsed asymmetric excitation is applied to the excitation coil to ensure that the magnetic field lines converge to the arc area within the non-magnetic / ferromagnetic narrow gap groove and are symmetrically distributed. This ensures that the arc produces stable, controllable, and symmetrical periodic oscillations under the action of the magnetic field, breaking through the limitations of the magnetic blow effect in the welding of dissimilar base materials.

[0018] 2. Driven by the magnetic field, the swinging arc deflects periodically, directly increasing the heat input to the sidewalls of the narrow gap groove, making the penetration of the ferromagnetic sidewall and the non-magnetic sidewall uniform, improving the sidewall fusion rate, and eliminating the lack of fusion defects caused by insufficient heat input.

[0019] 3. The mechanical oscillation of the swinging arc and the molten pool flow induced by the magnetic field work together to achieve a uniform distribution of the temperature field and alloying elements in the molten pool. At the same time, the grain size is refined during the rapid solidification of the molten pool, which significantly improves the toughness of the weld and inhibits the initiation of welding cracks.

[0020] 4. In view of the magneto-induced vibration effect of ferromagnetic steel base material and the eddy current thermal effect of non-ferromagnetic steel base material, the magnetic shoe spacing and magnetic field parameters can be dynamically adjusted to achieve a balanced distribution of magnetic field intensity at the interface of dissimilar materials and improve the tensile strength of the dissimilar base material joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0022] Figure 1 A schematic diagram of the structure of the device provided by the present invention;

[0023] FIG2(a) is a front view of the cooling device provided by the present invention; FIG2(b) is a left view of the cooling device provided by the present invention; FIG2(c) is a top view of the cooling device provided by the present invention; FIG2(d) is an axonometric view of the cooling device provided by the present invention;

[0024] Figure 3 A schematic diagram of the waveform of the asymmetric alternating excitation current provided by the present invention;

[0025] Figure 4 A schematic flow chart of the method provided by the present invention;

[0026] FIG5( a ) is a schematic diagram of the arc shape when a symmetrical alternating excitation current is used; FIG5( b ) is a schematic diagram of the arc shape when an asymmetrical alternating excitation current is used.

[0027] In the figure, 1 is a TIG welding gun; 2 is an excitation core; 3 is an excitation coil; 4 is a welding wire; 5 is a non-ferromagnetic steel base material; 6 is a ferromagnetic steel base material (5 and 6 form a narrow gap welding groove); 7 is a magnetic shoe; 8 is a welding gun support; 9 is a welding power supply; 10 is a pulse excitation power supply; 11 is a wire feeder; and 12 is a cooling device. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] On the one hand, the embodiment of the present invention discloses a thick-walled dissimilar metal TIG narrow gap welding device based on a magnetron arc, which aims to provide an excitation condition for realizing effective arc swing in the narrow gap groove of non-magnetic / ferromagnetic dissimilar steel to meet the periodic swing of the magnetron arc, and solve the problem of poor fusion of the inner side wall of the narrow gap groove of non-magnetic / ferromagnetic dissimilar steel. Figure 1 As shown, it includes: an excitation coil 3, a pulse excitation power supply 10, an excitation core 2, a magnetic shoe 7, a welding gun support 8, a TIG welding gun 1 and a cooling device 12; the excitation core 2 and the TIG welding gun 1 are fixedly connected to the welding gun support 8; the excitation coil 3 is spirally wound on the excitation core 2; the excitation coil 3 is electrically connected to the pulse excitation power supply 10 to generate an alternating magnetic field; the excitation core 2 is fixedly connected to the magnetic shoe 7 to form a magnetic circuit conduction structure to conduct the alternating magnetic field to the welding area; a narrow gap groove is formed by combining non-magnetic base material and ferromagnetic base material; the alternating magnetic field acts on the arc space in the narrow gap groove; the cooling device 12 is fixed to the magnetic shoe 7 by interference fit to cool the magnetic shoe 7 to avoid a decrease in the magnetic conductivity of the magnetic shoe 7 at high temperature.

[0030] In one embodiment, the magnetic circuit is a gapped magnetic circuit, and the height of the magnetic circuit is 220-280 mm and the width is 100-180 mm.

[0031] In one embodiment, a welding power source 9 is further included, which is connected to the TIG welding gun 1 and is used to provide the current required for the welding arc.

[0032] Furthermore, the device includes an excitation coil 3, a pulse excitation power supply 10, an excitation core 2, a magnetic shoe 7 and a tungsten pole of a TIG welding gun 1, and the welding base material is a combination of non-magnetic / ferromagnetic thick-walled metal; the magnetic circuit as a whole adopts a double magnetic shoe magnetic circuit; the excitation core 2 and the welding gun support 8 are connected and fixed with an interference fit; the magnetic field is generated by the excitation current generated by the external pulse excitation power supply 10; the excitation core 2 and the magnetic shoe 7 constitute the magnetic circuit conduction part, and the two magnetic shoes 7 are rigidly fixed to the iron core through a threaded connection to conduct the magnetic lines of force to the arc space.

[0033] The tungsten electrode of the TIG welding gun 1 is fixed to the magnetic circuit device through the welding gun support 8, and the tungsten electrode is installed at the position of the central symmetric axis of the magnetic circuit.

[0034] In one embodiment, the magnetic circuit shape adopts a gap magnetic circuit to ensure the continuity of magnetic circuit conduction in the magnetic circuit. The magnetic circuit is 220-280 mm high and 100-180 mm wide. The magnetic shoe spacing is 10-25 mm to ensure that the magnetic lines of force are not attracted by the side wall of the ferromagnetic material on one side of the narrow gap groove to generate the magnetic induction intensity required for arc deflection.

[0035] In one embodiment, the excitation coil 3 is a single coil, which is made of copper enameled wire with a wire diameter of 1.2 mm and 650 to 1100 turns; and is wound on the iron core in a spiral winding form.

[0036] In one embodiment, the excitation core 2 is made of electrical silicon steel with a diameter of 8-15 mm.

[0037] In one embodiment, the magnetic shoe 7 is made of soft magnetic material electrical iron DT4C to ensure that the magnetic shoe 7 has a certain rigidity and is not disturbed or deformed by the ferromagnetic side wall, and is connected to the excitation core 2 through threads.

[0038] In one embodiment, the cooling device 12 is a water-cooled copper block. The number of the water-cooled copper blocks is the same as the number of the magnetic shoes 7. The water-cooled copper blocks are fixed to the magnetic shoes 7 by interference fit. Figure 2(a)-Figure 2(d) As shown, the water-cooled copper block 12 and the magnetic shoe 7 are in close contact through interference fit, forming an efficient heat conduction path; since the thermal conductivity of copper is much higher than that of ferromagnetic materials, the heat of the magnetic shoe 7 can be quickly transferred to the copper block; the heat is dissipated inside the copper block through a water cooling cycle, specifically: a closed water channel is designed inside the copper block, and cooling water flows through it at high speed under the drive of a pump. The water absorbs the heat of the copper block through convection heat transfer, so that the temperature of the magnetic shoe 7 is maintained within a normal range, thereby maintaining a stable magnetic permeability.

[0039] In one embodiment, the tungsten pole of the TIG welding gun 1 is fixed at the position of the central symmetric axis of the magnetic circuit.

[0040] Furthermore, the tip of the tungsten pole extends out of the plane where the lower end surface of the magnetic shoe 7 is located by 1 to 5 mm.

[0041] In one embodiment, the pulse excitation power supply 10 outputs an asymmetrical alternating excitation current, such as Figure 3 As shown, the arc corresponding to the maximum amplitude swings toward the non-magnetic base material side, and the arc corresponding to the minimum amplitude swings toward the ferromagnetic base material side.

[0042] Furthermore, the maximum amplitudes of the alternating excitation currents are not equal. The excitation current amplitude required for the arc to swing to the non-ferromagnetic steel base material 5 is greater than the excitation current amplitude required for the arc to swing to the ferromagnetic steel base material 6. The excitation frequency of the excitation current is 1-50Hz.

[0043] In one embodiment, a wire feeder 11 is further included for feeding the welding wire 4 to the front end of the TIG welding gun 1 .

[0044] On the other hand, this embodiment discloses a TIG narrow gap welding method for thick-walled dissimilar metals based on a magnetron arc, which is applied in the above-mentioned welding device, such as Figure 4 As shown, the specific steps are:

[0045] generating an alternating magnetic field based on a magnetic generating device;

[0046] The magnetic circuit conduction structure formed by the excitation core 2 and the magnetic shoe 7 focuses the alternating magnetic field on the arc space of the narrow gap groove;

[0047] A TIG welding gun 1 is used to ignite the arc in the arc space within the narrow gap groove. At the same time, the arc current is adjusted by the welding power supply 9 so that the arc produces periodic swings under the action of the alternating magnetic field and melts the welding wire 4 to fill the narrow gap groove. The narrow gap groove is formed by a combination of non-magnetic base material and ferromagnetic base material.

[0048] In one embodiment, the application steps of the welding method are:

[0049] The magnetic circuit device and the welding gun are installed in coordination to ensure that the air gap of the magnetic circuit is symmetrical about the central axis of the tungsten pole;

[0050] Before performing narrow gap magnetic swing arc welding of non-magnetic / ferromagnetic metals, check whether the magnetic coil can work normally, and then place the plates to be welded in the appropriate position;

[0051] Turn on the pulse excitation power supply 10, adjust the excitation waveform to make it work properly, and adjust the appropriate pulse excitation current amplitude;

[0052] Start the arc ignition button to ignite the arc and feed the wire to start arc swing narrow gap welding on the narrow gap groove of non-magnetic / ferromagnetic dissimilar metals;

[0053] After the arc is extinguished after the welding operation is completed, the excitation coil power switch is turned off after a short period of time, and the magnetic control swing arc welding in the narrow gap groove of non-magnetic / ferromagnetic dissimilar steel is completed.

[0054] Furthermore, during narrow-gap welding of non-magnetic / ferromagnetic dissimilar steels, when the excitation coil 3 is fed with an asymmetric alternating excitation current provided by a pulsed excitation power supply 10, the magnetic field generated by the magnetic shoe 7 is perpendicular to the welding torch axis and parallel to the weld seam, thereby deflecting the arc onto the metal sidewalls on both sides during welding. By supplying an alternating current, the arc generates a continuously changing magnetic field, deflecting the arc onto different metal sidewalls. The forced magnetic field eliminates arc blow, while the molten welding wire 4 forms a good fusion with the sidewalls under the action of the oscillating arc. This effectively eliminates poor fusion of the magnetic groove sidewalls and improves weld formation during narrow-gap welding.

[0055] Furthermore, the arc swing was observed in a narrow-gap groove of 30mm thick 304 non-ferromagnetic stainless steel / ferromagnetic steel Q235b carbon steel. A square seamless narrow-gap groove was used with a groove width of 11mm, a depth of 20mm, a welding current of 160A, and a tungsten electrode height of 3mm. The excitation current was I a 5.5A, I b The excitation frequency is 3.2A, the excitation frequency is 4Hz, and the entire welding process is protected by pure argon gas with an argon gas flow rate of 15L / min. The tungsten tip of the TIG welding gun 1 extends 3mm from the lower end surface of the magnetic shoe 7 and matches the relevant welding parameters. Among them, Figure 5(a) uses a symmetrical alternating excitation current (3A), and Figure 5(b) uses an asymmetrical alternating excitation current (I a 5.5A, I b It is obvious that under asymmetric excitation, the arc deflection amplitudes on both sides of the narrow gap groove are almost the same.

[0056] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0057] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A thick-walled dissimilar metal TIG narrow gap welding device based on magnetron arc, characterized in that: include: An excitation coil (3), a pulse excitation power supply (10), an excitation core (2), a magnetic shoe (7), a welding gun support (8), a TIG welding gun (1) and a cooling device (12); the excitation core (2) and the TIG welding gun (1) are both fixedly connected to the welding gun support (8); the excitation coil (3) is spirally wound on the excitation core (2); the excitation coil (3) is electrically connected to the pulse excitation power supply (10) to generate an alternating magnetic field; the excitation core (2) is fixedly connected to the magnetic shoe (7) to form a magnetic circuit conduction structure to conduct the alternating magnetic field to the welding area; the welding area adopts a combination of non-magnetic base material and ferromagnetic base material to form a narrow gap groove; the alternating magnetic field acts on the arc space in the narrow gap groove; the cooling device (12) is fixed to the magnetic shoe (7) by interference fit to cool the magnetic shoe (7).

2. The thick-walled dissimilar metal TIG narrow gap welding device based on magnetron arc according to claim 1, characterized in that: The magnetic shoes (7) adopt a double magnetic shoe structure, and the magnetic shoe spacing is 18-25 mm.

3. The thick-walled dissimilar metal TIG narrow gap welding device based on magnetron arc according to claim 1, characterized in that: The magnetic shoe (7) is made of soft magnetic material electrical iron DT4C.

4. The thick-walled dissimilar metal TIG narrow gap welding device based on magnetron arc according to claim 1, characterized in that: The tungsten pole of the TIG welding gun (1) is fixed on the central symmetric axis of the magnetic circuit.

5. The thick-walled dissimilar metal TIG narrow gap welding device based on magnetron arc according to claim 4, characterized in that: The magnetic circuit is a gap-containing magnetic circuit with a height of 220-280 mm and a width of 100-180 mm.

6. The thick-walled dissimilar metal TIG narrow gap welding device based on magnetron arc according to claim 1, characterized in that: The pulse excitation power supply (10) outputs an asymmetric alternating excitation current, wherein the arc corresponding to the maximum amplitude swings toward the non-magnetic base material side, and the arc corresponding to the minimum amplitude swings toward the ferromagnetic base material side.

7. The thick-walled dissimilar metal TIG narrow gap welding device based on magnetron arc according to claim 1, characterized in that: It also includes a welding power source (9) which is connected to the TIG welding gun (1) and is used to provide the current required by the welding arc.

8. A method for thick-walled dissimilar metal TIG narrow gap welding based on a magnetron arc, applied to a thick-walled dissimilar metal TIG narrow gap welding device based on a magnetron arc as claimed in any one of claims 1 to 7, characterized in that: The specific steps are: generating an alternating magnetic field based on a magnetic generating device; The alternating magnetic field is focused on the arc space of the narrow gap groove through a magnetic circuit conduction structure formed by an excitation core (2) and a magnetic shoe (7); A TIG welding gun (1) is used to ignite an arc in an arc space within a narrow-gap groove, and simultaneously a welding power source (9) is used to adjust the arc current so that the arc generates periodic swings under the action of the alternating magnetic field, and melts the welding wire (4) to fill the narrow-gap groove; the narrow-gap groove is formed by a combination of a non-magnetic base material and a ferromagnetic base material.

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