Magnetron-arc-based thick-walled dissimilar metal TIG narrow-gap welding apparatus and method

Abstract

The application discloses a kind of thick-wall dissimilar metal TIG narrow-gap welding device and method based on magnetic control arc, it is related to dissimilar welding technical field, including: excitation core, TIG welding torch is fixedly connected with welding torch support body;Excitation core is spirally wound with excitation coil;Excitation coil is electrically connected with pulse excitation power supply, generates alternating magnetic field;Excitation core and magnetic shoe form magnetic circuit conduction structure, and alternating magnetic field is conducted to welding area;Welding area adopts non-magnetic base material and ferromagnetic base material combination to form narrow-gap groove;Alternating magnetic field acts on arc space in narrow-gap groove;Cooling device is fixed with magnetic shoe interference fit, and the cooling of magnetic shoe is carried out.The present application applies asymmetric pulse excitation to excitation coil, and forms symmetric magnetic field in arc area in non-magnetic / ferromagnetic narrow-gap groove, to ensure that arc produces stable, controllable periodic swing under the action of magnetic field.

Description

Technical Field

[0001] This invention relates to the field of dissimilar metal welding technology, and more specifically to a device and method for thick-walled dissimilar metal TIG narrow-gap welding based on a magnetically controlled electric arc. Background Technology

[0002] Currently, magnetically controlled oscillating arc welding (TIG) technology, by regulating the arc morphology and molten pool behavior through a magnetic field, can reconstruct the arc energy distribution and increase the heat input to the sidewalls of narrow-gap welds, thereby effectively suppressing incomplete fusion defects. Simultaneously, it achieves uniform temperature field and alloy element distribution through molten pool stirring, and has been widely applied to narrow-gap welding of the same materials. However, for welding thick-walled composite components of non-magnetic / ferromagnetic dissimilar steels (e.g., 304 austenitic stainless steel and Q235b carbon steel), the significant differences in the magnetic physical properties of the base materials make traditional TIG welding susceptible to magnetic blow effects. This leads to decreased stability of the symmetrical arc oscillation, unbalanced molten pool flow, and consequently, incomplete fusion defects and joint performance degradation. Furthermore, the sensitivity of ferromagnetic materials to magnetic field distribution makes it difficult for existing magnetically controlled oscillating arc welding technology to achieve uniform and controllable arc oscillation and magnetic field coupling within narrow-gap grooves of dissimilar steels. Therefore, designing a magnetically controlled arc oscillation method suitable for narrow-gap welding of non-magnetic / ferromagnetic dissimilar steels to overcome the magnetic blow effect and coordinate the differences in magnetic field response between dissimilar materials is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

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

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A narrow-gap TIG welding device for thick-walled dissimilar metals based on a magnetically controlled arc includes: an excitation coil, a pulsed excitation power supply, an excitation core, a magnetic shoe, a welding torch support, a TIG welding torch, and a cooling device. The excitation core and the TIG welding torch are both fixedly connected to the welding torch support. The excitation coil is spirally wound around the excitation core. The excitation coil is electrically connected to the pulsed excitation power supply to generate an alternating magnetic field. The excitation core is fixedly connected to the magnetic shoe, forming a magnetic circuit conduction structure that conducts the alternating magnetic field to the welding area. The welding area uses a combination of non-magnetic and ferromagnetic base materials to form a narrow-gap bevel. The alternating magnetic field acts on the arc space within the narrow-gap bevel. The cooling device is interference-fitted and fixed to the magnetic shoe to cool it.

[0006] Furthermore, the magnetic boot adopts a double magnetic boot structure, and the magnetic boot spacing is 18-25mm.

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

[0008] Furthermore, the tungsten electrode of the TIG welding torch is fixed at the position of the central axis of symmetry of the magnetic circuit.

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

[0010] Furthermore, the pulsed excitation power supply outputs an asymmetrical alternating excitation current, with the arc corresponding to the maximum amplitude swinging towards the non-magnetic base material side and the arc corresponding to the minimum amplitude swinging towards the ferromagnetic base material side.

[0011] Furthermore, it also includes a welding power source, which is connected to the TIG welding torch to provide the current required for the welding arc.

[0012] A method for narrow-gap TIG welding of thick-walled dissimilar metals based on magnetron-controlled arc, comprising the following steps:

[0013] An alternating magnetic field is generated based on a magnetic generator;

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

[0015] The arc is ignited in the narrow gap groove using a TIG welding torch. At the same time, the arc current is adjusted by the welding power source, so that the arc oscillates periodically 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 non-magnetic base material and ferromagnetic base material.

[0016] As can be seen from the above technical solution, compared with the prior art, the present invention provides a device and method for narrow-gap TIG welding of thick-walled dissimilar metals based on magnetically controlled electric arc, which has the following beneficial effects:

[0017] 1. By using a small-gap magnetic circuit design (combination of excitation core and magnetic shoe), the magnetic field strength can be improved; by applying pulsed asymmetric excitation to the excitation coil, the magnetic field lines are ensured to converge to the arc region within the non-magnetic / ferromagnetic narrow gap groove and be symmetrically distributed, ensuring that the arc produces stable, controllable, and symmetrical periodic oscillations under the action of the magnetic field, thus overcoming the limitation of magnetic blow effect in welding dissimilar base materials.

[0018] 2. The oscillating arc deflects periodically under the drive of the magnetic field, directly increasing the heat input to the narrow gap bevel sidewall, making the melting depth of the ferromagnetic sidewall and the non-magnetic sidewall more uniform, improving the sidewall fusion rate, and eliminating incomplete fusion defects caused by insufficient heat input.

[0019] 3. The mechanical oscillation of the oscillating arc and the magnetic field-induced flow of the molten pool work together to achieve a uniform distribution of temperature field and alloying elements in the molten pool. At the same time, the grains are 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. To address the magnetostrictive vibration effect of ferromagnetic steel base material and the eddy current thermal effect of non-ferromagnetic steel base material, the magnetic field strength at the interface of dissimilar materials can be evenly distributed by dynamically adjusting the magnetic shoe spacing and magnetic field parameters, thereby improving the tensile strength of the dissimilar base material joint. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

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

[0023] Figure 2(a) is a front view of the cooling device provided by the present invention; Figure 2(b) is a left view of the cooling device provided by the present invention; Figure 2(c) is a top view of the cooling device provided by the present invention; Figure 2(d) is an isometric view of the cooling device provided by the present invention.

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

[0025] Figure 4 This is a schematic diagram of the method flow provided by the present invention;

[0026] Figure 5(a) is a schematic diagram of the arc shape using symmetrical alternating excitation current; Figure 5(b) is a schematic diagram of the arc shape using asymmetrical alternating excitation current.

[0027] In the diagram, 1 is the TIG welding torch; 2 is the excitation core; 3 is the excitation coil; 4 is the welding wire; 5 is the non-ferromagnetic steel base material; 6 is the ferromagnetic steel base material (5 and 6 form a narrow gap welding bevel); 7 is the magnetic shoe; 8 is the welding torch support; 9 is the welding power source; 10 is the pulse excitation power source; 11 is the wire feeder; and 12 is the cooling device. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] One embodiment of this invention discloses a thick-walled dissimilar metal TIG narrow-gap welding device based on a magnetically controlled arc. It provides excitation conditions for effective arc oscillation within the narrow-gap groove of non-magnetic / ferromagnetic dissimilar steels, satisfying the periodic oscillation of the magnetically controlled arc. This solves the problem of poor fusion of the inner sidewall of the narrow-gap groove in non-magnetic / ferromagnetic dissimilar steels. Its structure is as follows: 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 torch support 8, a TIG welding torch 1, and a cooling device 12; the excitation core 2 and the TIG welding torch 1 are both fixedly connected to the welding torch 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, which conducts the alternating magnetic field to the welding area; a narrow gap bevel is formed by combining non-magnetic and ferromagnetic base materials; the alternating magnetic field acts on the arc space within the narrow gap bevel; the cooling device 12 is fixed to the magnetic shoe 7 with an interference fit to cool the magnetic shoe 7 and prevent the magnetic permeability of the magnetic shoe 7 from decreasing at high temperatures.

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

[0031] In one embodiment, a welding power source 9 is also included, which is connected to the TIG welding torch 1 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, magnetic shoes 7, and a tungsten electrode of a TIG welding torch 1. The base material for welding is a combination of non-magnetic / ferromagnetic thick-walled metallic materials. The overall magnetic circuit adopts a double magnetic shoe circuit. The excitation core 2 and the welding torch support 8 are connected and fixed with an interference fit. A magnetic field is generated by the excitation current generated by the externally supplied pulse excitation power supply 10. The excitation core 2 and the magnetic shoes 7 constitute the magnetic circuit conduction part. The two magnetic shoes 7 are rigidly fixed to the iron core through a threaded connection, which conducts the magnetic lines of force to the arc space.

[0033] In this device, the tungsten electrode of the TIG welding torch 1 is fixed to the magnetic circuit device through the welding torch support 8, and the tungsten electrode is installed at the position of the central symmetrical axis of the magnetic circuit.

[0034] In one embodiment, the magnetic circuit shape adopts a gap-containing magnetic circuit to ensure the continuity of magnetic circuit conduction. The magnetic circuit height is 220-280mm and the width is 100-180mm. The magnetic shoe spacing is 10-25mm to ensure that the magnetic lines of force are not attracted by the ferromagnetic material sidewall on the narrow gap bevel side, so as 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 diameter of 1.2 mm and has 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 8-15mm.

[0037] In one embodiment, the magnetic shoe 7 is made of soft magnetic material DT4C electrical iron, which ensures that the magnetic shoe 7 has a certain rigidity and is not deformed by the ferromagnetic sidewalls. It is connected to the excitation core 2 by threads.

[0038] In one embodiment, the cooling device 12 is a water-cooled copper block, the number of which is the same as the number of magnetic shoes 7. The water-cooled copper blocks are fixed to the magnetic shoes 7 with an interference fit, and its structure is as follows. Figures 2(a)-2(d) As shown, the water-cooled copper block 12 and the magnetic shoe 7 are in close contact through an 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 copper block dissipates heat through a water-cooling circulation. Specifically, the copper block is designed with a closed water channel. Cooling water flows through it at high speed under the drive of a pump. The water flow absorbs the heat of the copper block through convection heat transfer, so that the temperature of the magnetic shoe 7 is maintained within the normal range, thereby maintaining a stable magnetic permeability.

[0039] In one embodiment, the tungsten electrode of the TIG welding torch 1 is fixed at the position of the central axis of symmetry of the magnetic circuit.

[0040] Furthermore, the tip of the tungsten electrode extends 1–5 mm beyond the plane of the lower end face of the magnetic shoe 7.

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

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

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

[0044] Another aspect of this embodiment discloses a narrow-gap TIG welding method for thick-walled dissimilar metals based on a magnetically controlled arc, which is applied in the aforementioned welding apparatus, such as... Figure 4 As shown, the specific steps are as follows:

[0045] An alternating magnetic field is generated based on a magnetic generator;

[0046] The alternating magnetic field is focused into the arc space of the narrow gap bevel by the magnetic circuit conduction structure formed by the excitation core 2 and the magnetic shoe 7.

[0047] The TIG welding torch 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 source 9, so that the arc oscillates periodically 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 as follows:

[0049] The magnetic circuit device and welding torch are installed together to ensure that the air gap of the magnetic circuit is symmetrical about the central axis of the tungsten electrode;

[0050] Before performing narrow-gap magnetron oscillating arc welding of non-magnetic / ferromagnetic metals, check that the magnetron coil is working properly, and then place the plate to be welded in the appropriate position.

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

[0052] Start the arc ignition button to ignite the arc and cooperate with wire feeding to begin arc oscillation narrow gap welding in the narrow gap groove of non-magnetic / ferromagnetic dissimilar metals;

[0053] After the welding operation is completed and the arc is extinguished, the excitation coil energizing switch is turned off after a short period of time, thus ending the welding of the magnetically controlled oscillating arc within the narrow gap bevel of the non-magnetic / ferromagnetic dissimilar steel.

[0054] Furthermore, during the narrow-gap welding of non-magnetic / ferromagnetic dissimilar steels, when the excitation coil 3 is supplied with an asymmetrical alternating excitation current provided by the pulsed excitation power supply 10, the magnetic field generated by the magnetic shoe 7 is perpendicular to the axis of the welding torch and parallel to the weld direction, thereby deflecting the arc to the metal sidewalls on both sides during the welding process. By passing an alternating current, a magnetic field with a constantly changing direction is generated, causing the arc to deflect to the metal sidewalls on different sides. Under the action of the forced magnetic field, the magnetic blowout of the arc is eliminated, and at the same time, the molten welding wire 4 forms good fusion on the sidewall under the action of the oscillating arc, which effectively solves the problem of poor fusion on the sidewall of the magnetic groove and improves the weld formation during the narrow-gap welding process.

[0055] Furthermore, the arc oscillation was observed within a narrow-gap bevel of 304 non-ferromagnetic stainless steel / ferromagnetic Q235b carbon steel with a thickness of 30mm. A square seamless narrow-gap bevel was used, with a bevel width of 11mm and a depth of 20mm. The welding current was 160A, and the tungsten electrode height was 3mm. The excitation current was I. a It is 5.5A, I b The excitation current is 3.2A, the excitation frequency is 4Hz, and pure argon gas is used for protection throughout the welding process at a flow rate of 15L / min. The tungsten electrode tip of the TIG welding torch 1 extends 3mm beyond the lower end face of the magnetic shoe 7 and is matched with the relevant welding parameters. Figure 5(a) shows the effect using a symmetrical alternating excitation current (3A), and Figure 5(b) shows the effect using an asymmetrical alternating excitation current (I...). a For 5.5A,I b The arc state diagram for 3.2A shows that, under asymmetric excitation, the deflection amplitude of the arc on both sides of the narrow gap bevel is almost the same.

[0056] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0057] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those 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 invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A thick walled dissimilar metal TIG narrow gap welding apparatus based on a magnetron arc, characterized by, include: The system comprises an excitation coil (3), a pulse excitation power supply (10), an excitation core (2), a magnetic shoe (7), a welding torch support (8), a TIG welding torch (1), and a cooling device (12). The excitation core (2) and the TIG welding torch (1) are fixedly connected to the welding torch 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, which conducts the alternating magnetic field to the welding area. The welding area is formed by a combination of non-magnetic and ferromagnetic base materials to create a narrow gap bevel. The alternating magnetic field acts on the arc space within the narrow gap bevel. The cooling device (12) is fixedly fitted to the magnetic shoe (7) to cool the magnetic shoe (7). The pulse excitation power supply (10) outputs an asymmetrical alternating excitation current, with the arc corresponding to the maximum amplitude swinging towards the non-magnetic base material side and the arc corresponding to the minimum amplitude swinging towards the ferromagnetic base material side. The melting depth of ferromagnetic and nonmagnetic sidewalls is made more uniform; By dynamically adjusting the magnetic shoe spacing and magnetic field parameters, a balanced distribution of magnetic field strength can be achieved at the interface of dissimilar materials.

2. A thick walled dissimilar metal TIG narrow gap welding apparatus based on a magnetron arc as claimed in claim 1, wherein, The magnetic boot (7) adopts a double magnetic boot structure with a magnetic boot spacing of 18-25mm.

3. A thick walled dissimilar metal TIG narrow gap welding apparatus based on a magnetron arc as claimed in claim 1, wherein, The magnetic shoe (7) is made of soft magnetic material DT4C.

4. A thick walled dissimilar metal TIG narrow gap welding apparatus based on a magnetron arc as claimed in claim 1, wherein, The tungsten electrode of the TIG welding torch (1) is fixed at the position of the central axis of symmetry of the magnetic circuit.

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

6. A thick walled dissimilar metal TIG narrow gap welding apparatus based on a magnetron arc as claimed in claim 1, wherein, It also includes a welding power source (9), which is connected to the TIG welding torch (1) to provide the current required for the welding arc.

7. A method for narrow-gap TIG welding of thick-walled dissimilar metals based on a magnetically controlled arc, applied in a magnetically controlled arc welding apparatus for narrow-gap TIG welding of thick-walled dissimilar metals as described in any one of claims 1-6, characterized in that, The specific steps are as follows: An alternating magnetic field is generated based on a magnetic generator; The alternating magnetic field is focused into the arc space of the narrow gap bevel by the magnetic circuit conduction structure formed by the excitation core (2) and the magnetic shoe (7); The TIG welding torch (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 source (9) so that the arc oscillates periodically 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.

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