Narrow gap welding device and method for zone control of welding heat input

Abstract

The invention discloses a narrow-gap welding device and a narrow-gap welding method for zone control of welding heat input, and belongs to the technical field of narrow-gap welding. Comprising a swing arc welding gun and a welding wire. The swing electric arc welding gun comprises a cable connector, a servo motor, a hollow speed reducer, a bent conducting rod and a contact tube. The system further comprises a power supply circuit, a servo motor controller and a synchronous controller. The power supply circuit comprises a coupling power source and a welding power source. The servo motor controller sends out a pulse signal to control the servo motor to rotate; the servo motor indirectly drives the conductive nozzle to rotate around the central axis of the bent conductive rod through the hollow speed reducer, so that the electric arc is driven to swing in the narrow-gap groove; the servo motor controller is configured to generate a rotation position signal and transmit the rotation position signal to the synchronous controller; the synchronous controller responds to the rotation position signal and executes synchronous control operation on the coupled power supply switch so as to dynamically switch on and off the coupled power supply according to the position area where the electric arc is located, and therefore partition control heat input of the electric arc is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of narrow gap welding, and in particular relates to a narrow gap welding device and method for controlling welding heat input by partitions. Background Art

[0002] Thick plate welding is widely used in large steel structures such as pressure vessels, marine engineering, and rail transit. Currently, large-angle V-grooves are the primary method for welding thick plates. This type of groove can result in high weld filler volume, low welding efficiency, and significant weld deformation.

[0003] Narrow gap welding is a highly efficient welding method that uses a small-angle I-shaped groove (the groove angle is ≤5°) for welding. Therefore, it has many advantages such as high welding efficiency, low welding cost and low heat input. However, when conventional arc welding methods such as TIG (Tungsten Inert Gas Welding), MAG (Metal Active Gas Welding) and SAW (Submerged Arc Welding) are used to weld the groove of narrow gap welding, it is impossible to ensure that the side walls of the narrow gap are fully fused. Especially when welding thick heat-resistant steel plates in the pressure vessel field, due to the poor fluidity of the molten pool, it is difficult to wet and spread to the side walls, which can easily cause defects such as lack of side wall fusion, middle convex welds, lack of interlayer fusion and slag inclusions.

[0004] To address these shortcomings, institutions such as the Sino-Uzbek Welding Research Institute of the Guangdong Academy of Sciences, Harbin Institute of Technology, and Jiangsu University of Science and Technology have conducted in-depth research and development of narrow-gap welding methods, including swinging arc, twin-wire, and rotating arc welding. These methods utilize wire motion to increase the arc's heat input to the sidewall. For example, Chinese Patent Publication No. CN1323788C discloses a hollow-shaft motor-driven rotating arc narrow-gap welding method and device. The device utilizes a hollow-shaft motor to directly drive a conductive rod, which in turn drives a straight conductive nozzle that can be inserted into the gap. A single compression spring ensures a tight sliding fit between the brush and the flange of the conductive rod. Power is supplied to the brush via a cable secured to the brush and a connector, creating a conductive connection. This generates a rotating arc at the end of the welding wire, which passes through the motor's hollow shaft and the conductive rod's center hole and emerges from the conductive nozzle's eccentric hole. Furthermore, various nozzle mechanisms are employed to achieve rotating arc narrow-gap welding.

[0005] The narrow gap welding method mentioned above can solve the problem of side wall incomplete fusion to a certain extent, but it still has the following disadvantages in practical applications:

[0006] (1) Since the welding parameters (such as current, voltage, etc.) used for the welding wire on the side wall of the groove are the same as those in the middle of the groove, in order to increase the heat input of the side wall, the welding parameters of the side wall and the middle of the groove need to be increased at the same time. This will lead to a larger overall heat input and molten pool, which is easy to cause problems such as molten pool flow in non-flat welding positions.

[0007] (2) Since the amount of welding wire melted in the middle of the groove is large, and the viscosity of the heat-resistant steel material is large and difficult to spread, the middle of the molten pool bulges, and the phenomenon of unfused interlayers and unfused side walls is prone to occur in the next welding.

[0008] (3) The molten pool has a large contact area with the side wall and heat transfer is fast. In order to allow the molten pool to wet and spread on the side wall, the heat input to the side wall needs to be increased. However, the existing method only increases the residence time on the side wall, and the welding parameters are not increased. This results in the need to weld at a very low welding speed (about 120mm / min) in actual operation to ensure sufficient fusion of the side wall. Summary of the Invention

[0009] In response to the problems in the related art, the present invention proposes a narrow gap welding device and method for zoned control of welding heat input to overcome the above-mentioned technical problems existing in the existing related art. The present invention realizes zoned control of heat input on the side wall and the middle position of the groove, and can ensure that the heat input in the middle of the groove does not increase while the heat input on the side wall of the groove increases, so as to reduce the size of the molten pool, thereby facilitating the realization of narrow gap welding in non-flat welding positions.

[0010] The technical solution of the present invention is achieved as follows: a narrow gap welding device with zoned control of welding heat input, comprising an oscillating arc welding gun and a welding wire for welding a narrow gap groove of a substrate to be welded, wherein the substrate to be welded comprises a thick plate;

[0011] The swing arc welding gun includes a cable connector, a servo motor, a hollow reducer, a curved conductive rod, and a conductive nozzle. The servo motor is drivingly connected to the hollow reducer, and the curved conductive rod is transmission-connected to the hollow reducer. The curved conductive rod includes a head end and a tail end. The head end passes through the center hole of the hollow reducer and extends toward the cable connector, and the tail end is bent and formed to fit the conductive nozzle. When power is applied, an arc is formed between the end of the conductive nozzle and the welding wire.

[0012] Furthermore, the motor shaft of the servo motor is connected to the input shaft of the hollow reducer;

[0013] The device further comprises a power supply circuit, a servo motor controller and a synchronous controller, wherein the power supply circuit comprises a coupling power supply and a welding power supply; the servo motor is electrically connected to the servo motor controller, the servo motor controller is electrically connected to the synchronous controller, and the synchronous controller is electrically connected to the coupling power supply; the coupling power supply comprises an output positive electrode and an output negative electrode; the welding power supply comprises a power supply positive electrode and a power supply negative electrode; the output positive electrode and the power supply positive electrode are connected in parallel to the electrical input end of the cable connector, and the output negative electrode and the power supply negative electrode are connected in parallel to the electrical input end of the base material to be welded;

[0014] Furthermore, the output positive electrode is electrically connected to the electrical input end of the cable connector through a coupling cable, and the power supply positive electrode is electrically connected to the electrical input end of the cable connector through a welding gun cable; the output negative electrode is electrically connected to the electrical input end of the substrate to be welded through a coupling cable, and the power supply negative electrode is electrically connected to the electrical input end of the substrate to be welded through a ground cable;

[0015] The servo motor controller sends a pulse signal to control the servo motor to rotate forward or reversely by an angle A; the servo motor indirectly drives the conductive nozzle to rotate forward or reversely by an angle A around the central axis of the curved conductive rod through a hollow reducer, thereby driving the arc to swing forward or reversely inside the narrow gap groove, thereby achieving swing arc narrow gap welding;

[0016] The servo motor controller is configured to generate a rotational position signal and transmit it to a synchronous controller, wherein the rotational position signal is used to characterize the rotational position of the servo motor; the synchronous controller performs a synchronous control operation on the coupling power switch in response to the received rotational position signal to dynamically turn on or off the coupling power supply according to the position area of ​​the arc, thereby realizing partitioned control of the arc heat input during narrow gap welding.

[0017] Furthermore, a first high-power diode is installed between the positive pole of the power supply and the electrical input end of the cable connector; a second high-power diode is installed between the positive output pole and the electrical input end of the cable connector; wherein the positive pole of the first high-power diode is connected to the positive pole of the power supply, and the positive pole of the second high-power diode is connected to the positive output pole.

[0018] Furthermore, the output welding current I1 of the welding power supply;

[0019] When the welding wire swings away from the groove side wall, the synchronous controller disconnects the coupling power supply, and the total arc current is I 总 =I1;

[0020] Preferably, the value range of I1 is 100A-300A, and the value range of I2 is 10A-100A; in practical applications, the values ​​of I1 and I2 can be adjusted during the welding process;

[0021] When the welding wire swings to the side wall of the groove, the synchronous controller turns on the coupling power supply. At this time, the output coupling current of the coupling power supply is I2, and the total current of the arc is I 总 =I1+I2;

[0022] Preferably, when I 总 =I1+I2, I 总 The value range is 100A-500A.

[0023] Furthermore, the parameters of the coupling current I2 need to adjust the magnitude of the welding current I1 according to the actual welding effect; the output current of the coupling power supply and the welding power supply are respectively in the form of a constant current and a pulse current, and the output current matching load characteristic is an impedance characteristic, wherein the matching load resistance is 0.1-0.6 ohms;

[0024] The actual welding effect includes whether the groove sidewall is fully fused or not; when the groove sidewall is not fully fused, the current value of the coupling current I2 is increased; when the groove sidewall is fully fused, the current value of the coupling current I2 is reduced;

[0025] It should be noted that, in the present invention, by adjusting the magnitude of the coupling current I2, the heat input at the sidewalls of the groove can be increased without increasing the heat input in the middle of the groove, thereby facilitating the control of weld formation and ensuring sidewall fusion. The invention is applicable to the welding of thick-walled structures with poor molten metal fluidity, such as heat-resistant steel, high-strength steel, aluminum alloy, and stainless steel. Furthermore, at a relatively low wire feed speed, all-position narrow-gap welding can be achieved, and sidewall fusion can be ensured by adjusting the coupling current I2.

[0026] It should be further explained that if the groove sidewall is not fully fused, the current value of the coupling current I2 should be increased. If the molten pool is too large, especially when welding in a non-flat welding position, the molten pool flows, and the current value of the coupling current I2 should be reduced.

[0027] Furthermore, the servo motor includes a photoelectric encoder, which is connected to the servo motor controller. The photoelectric encoder is used to feed back the rotation angle and direction of the servo motor to the servo motor controller.

[0028] Furthermore, the photoelectric encoder feeds back the forward or reverse rotation angle A of the motor shaft of the servo motor to the servo motor controller in the form of a digital signal; the servo motor controller transmits the rotation position signal to the synchronous controller, and the synchronous controller obtains the rotation angle A by measuring the digital signal;

[0029] It should be noted that: when the angle A is rotated in the positive direction, A is a positive number; when the angle A is rotated in the reverse direction, A is a negative number;

[0030] The synchronous controller is preset with a reference angle B and a threshold value C. The synchronous controller determines whether the motor shaft of the servo motor has rotated to a preset position according to the formula: |AB|≤C;

[0031] Furthermore, if the absolute value of AB is ≤C, the synchronous controller confirms that the motor shaft of the servo motor has rotated to a preset position; and, at this time, the arc is at the side wall of the groove, and the synchronous controller responds to the received rotation position signal and turns off the switch of the coupling power supply, so that the side wall of the groove is fully fused.

[0032] Furthermore, the bending angle of the tail end of the curved conductive rod relative to the central axis of the curved conductive rod is 10°; after the absolute value of the rotation angle A is taken, its numerical range is 30°-90°.

[0033] Furthermore, the welding power supply is one of a TIG power supply, a MIG power supply, and a SAW power supply.

[0034] A narrow gap welding method for controlling welding heat input by partitioning is applied to the above-mentioned narrow gap welding device, and the method comprises the following steps:

[0035] Step S1: Presetting parameter values; presetting welding process parameters on the welding power supply, setting coupling current I2 on the coupling power supply, setting welding current I1 on the welding power supply, and setting swing parameters on the servo motor controller; wherein the positive output electrode of the coupling power supply and the positive power electrode of the welding power supply are connected in parallel to the electrical input end of the cable connector, and the negative output electrode of the coupling power supply and the negative power electrode of the welding power supply are connected in parallel to the electrical input end of the base material to be welded;

[0036] Step S2: Welding begins. After the welding wire strikes the arc, it begins to swing. The servo motor has a photoelectric encoder for feeding back the rotation angle and direction of the servo motor shaft to the servo motor controller. The servo motor controller transmits the rotation position signal to the synchronous controller. After the synchronous controller sets the hysteresis parameter, it controls the switch of the coupling power supply according to the rotation position signal. When the welding wire swings to the side wall of the groove, the synchronous controller turns on the switch of the coupling power supply. At this time, the current of the coupling power supply is I2, and the current passing through the arc is I 总 =I1+I2; When the welding wire swings away from the groove side wall, the synchronous controller turns off the switch of the coupling power supply, and the arc current is I 总 =I1;

[0037] Step S3: By adjusting the magnitude of the coupling current I2, the heat input at the groove sidewall is increased without increasing the heat input in the middle of the groove, thereby controlling the weld formation and ensuring the fusion of the sidewalls. When the groove sidewalls are not fully fused, the current value of the coupling current I2 is increased; when the groove sidewalls are fully fused, the current value of the coupling current I2 is reduced.

[0038] Furthermore, the welding process parameters include current and voltage; the swing parameters include swing angle, swing speed and side wall residence time; the swing angle has a value range of 30°-90°, and the swing speed has a value range of 0° / s-1440° / s.

[0039] Beneficial effects of the present invention:

[0040] (1) The present invention realizes the zoned control of heat input at the groove side wall and the middle position of the groove, and can ensure that the heat input at the middle position of the groove does not increase while the heat input at the groove side wall increases, thereby reducing the molten pool size, thereby facilitating the narrow gap welding in non-flat welding positions.

[0041] (2) The present invention allows welding at a lower wire feed speed, reducing the amount of wire melted in the center of the groove and suppressing the formation of a bulge in the center of the weld. Since the coupling current is increased at the sidewalls of the groove, sufficient fusion of the sidewalls can be ensured even at a lower wire feed speed. Thus, when welding low-alloy steels such as heat-resistant steel, better weld formation can be achieved even at a lower wire feed speed.

[0042] (3) The contact area of ​​the molten pool on the side wall of the groove is large and the heat transfer is fast. Therefore, in order for the molten pool to wet and spread on the side wall of the groove, it is necessary to increase the heat input of the side wall of the groove. After increasing the coupling current on the side wall of the groove, the heat input of the side wall of the groove can be effectively increased, and the residence time on the side wall can be reduced, thereby improving the overall welding speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a structural schematic diagram of the swing arc welding gun of the present invention;

[0044] Figure 2 is a cross-sectional view of an oscillating arc welding gun of the present invention;

[0045] Figure 3 for Figure 2 A magnified view of point A;

[0046] Figure 4 This is a schematic structural diagram of the oscillating arc welding gun of the present invention with some components removed;

[0047] Figure 5 This is a schematic structural diagram of a narrow gap welding device for controlling welding heat input in different zones according to the present invention.

[0048] Marking Description:

[0049] 1. Oscillating arc welding gun; 11. Cable connector; 12. Servo motor; 121. Motor shaft; 13. Hollow reducer; 14. Bent conductive rod; 15. Conductive nozzle. DETAILED DESCRIPTION

[0050] 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. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0051] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0052] Example 1

[0053] like Figure 1-5 As shown, this embodiment provides a narrow gap welding device for controlling welding heat input by partitions, comprising an oscillating arc welding gun 1 and a welding wire for welding a narrow gap groove of a substrate to be welded, wherein the substrate to be welded comprises a thick plate;

[0054] The swing arc welding gun 1 includes a cable connector 11, a servo motor 12, a hollow reducer 13, a curved conductive rod 14, and a conductive tip 15. The servo motor 12 is driven and connected to the hollow reducer 13, and the curved conductive rod 14 is transmission-connected to the hollow reducer 13. The curved conductive rod 14 includes a head end and a tail end. The head end passes through the center hole of the hollow reducer 13 and extends toward the cable connector 11. The tail end is bent and formed to cooperate with the conductive tip 15. When power is applied, an arc is formed between the end of the conductive tip 15 and the welding wire.

[0055] More specifically, the motor shaft 121 of the servo motor 12 is connected to the input shaft of the hollow reducer 13;

[0056] The device further comprises a power supply circuit, a servo motor controller and a synchronous controller, wherein the power supply circuit comprises a coupling power supply and a welding power supply; the servo motor 12 is electrically connected to the servo motor controller, the servo motor controller is electrically connected to the synchronous controller, and the synchronous controller is electrically connected to the coupling power supply; the coupling power supply comprises an output positive electrode and an output negative electrode; the welding power supply comprises a power supply positive electrode and a power supply negative electrode; the output positive electrode and the power supply positive electrode are connected in parallel to the electrical input end of the cable connector 11, and the output negative electrode and the power supply negative electrode are connected in parallel to the electrical input end of the base material to be welded;

[0057] Specifically, the output positive electrode is electrically connected to the electrical input end of the cable connector 11 through a coupling cable, and the power supply positive electrode is electrically connected to the electrical input end of the cable connector 11 through a welding gun cable; the output negative electrode is electrically connected to the electrical input end of the base material to be welded through a coupling cable, and the power supply negative electrode is electrically connected to the electrical input end of the base material to be welded through a ground cable;

[0058] The servo motor controller sends a pulse signal to control the servo motor 12 to rotate forward or reversely at an angle A; the servo motor 12 indirectly drives the conductive nozzle 15 to rotate forward or reversely at an angle A around the central axis of the curved conductive rod 14 through the hollow reducer 13, thereby driving the arc to swing forward or reversely inside the narrow gap groove, thereby achieving swing arc narrow gap welding;

[0059] The servo motor controller is configured to generate a rotational position signal and transmit it to the synchronous controller, wherein the rotational position signal is used to characterize the rotational position of the servo motor 12; the synchronous controller performs a synchronous control operation on the coupling power switch in response to the received rotational position signal to dynamically turn on or off the coupling power supply according to the position area of ​​the arc, thereby realizing partitioned control of the arc heat input during narrow gap welding.

[0060] First, through the coordinated control of the servo motor controller and synchronous controller, combined with the dynamic switching mechanism of the coupled power supply, real-time matching of the arc swing position and heat input parameters is achieved. This effectively solves the problems of interlayer incomplete fusion and weld deformation caused by uneven heat input in thick plate welding.

[0061] Moreover, through the drive connection between the servo motor 12 and the hollow reducer 13, and the transmission connection between the bent conductive rod 14 and the hollow reducer 13, the conductive nozzle 15 can rotate forward and reversely around the central axis of the bent conductive rod 14 by a certain angle, driving the arc to swing inside the narrow gap groove to complete narrow gap welding, which helps to adapt to the welding requirements of special workpieces such as thick plates and improve the flexibility and adaptability of welding.

[0062] In addition, through the parallel topology of the coupling cable and the welding gun cable, an electromagnetic compatibility channel between the high-frequency coupling current and the welding main current is constructed, which is beneficial to reducing the signal interference intensity of the servo control system and ensuring the transmission reliability of the rotation position signal.

[0063] Specifically, a first high-power diode is installed between the positive electrode of the power supply and the electrical input end of the cable connector 11; a second high-power diode is installed between the positive output electrode and the electrical input end of the cable connector 11; wherein the positive electrode of the first high-power diode is connected to the positive electrode of the power supply, and the positive electrode of the second high-power diode is connected to the positive output electrode;

[0064] The provision of the high-power diode is helpful in avoiding mutual interference between the coupling power supply and the welding power supply;

[0065] Specifically, the unidirectional conductivity of the diode effectively blocks the reverse current path between the coupling power supply and the welding power supply. During welding, the two power supplies output different signals. Without isolation measures, these signals can easily interfere with each other, leading to unstable power output and voltage fluctuations. By installing these two high-power diodes, reverse current can be prevented between the coupling power supply and the welding power supply, ensuring independent and stable output signals. This prevents power supply output anomalies caused by mutual interference and provides a stable and reliable power environment for the welding system.

[0066] Furthermore, the electromagnetic field generated by the welding power supply and the coupled power supply during operation can cause interference due to electromagnetic coupling, affecting power supply output accuracy and welding quality. The presence of a high-power diode can weaken this electromagnetic coupling, reducing the impact of interference on power supply output, ensuring stable parameters such as current and voltage during welding, and improving the repeatability and consistency of the welding process.

[0067] Specifically, the output welding current I1 of the welding power supply;

[0068] When the welding wire swings away from the groove side wall, the synchronous controller disconnects the coupling power supply, and the total arc current is I 总 =I1;

[0069] Preferably, the value range of I1 is 100A-300A, and the value range of I2 is 10A-100A; in practical applications, the values ​​of I1 and I2 can be adjusted during the welding process;

[0070] When the welding wire swings to the side wall of the groove, the synchronous controller turns on the coupling power supply. At this time, the output coupling current of the coupling power supply is I2, and the total current of the arc is I 总 =I1+I2;

[0071] Preferably, when I 总=I1+I2, I 总 The value range is 100A-500A.

[0072] The actual welding effect includes whether the groove sidewall is fully fused or not; when the groove sidewall is not fully fused, the current value of the coupling current I2 is increased; when the groove sidewall is fully fused, the current value of the coupling current I2 is reduced;

[0073] It should be noted that in this embodiment, by adjusting the magnitude of the coupling current I2, the heat input at the groove sidewalls can be increased without increasing the heat input in the middle of the groove, thereby facilitating the control of weld formation and ensuring sidewall fusion. This embodiment is suitable for welding thick-walled structures with poor molten metal fluidity, such as heat-resistant steel, high-strength steel, aluminum alloy, and stainless steel. At the same time, at a relatively low wire feed speed, all-position narrow-gap welding can be achieved, and sidewall fusion can be ensured by adjusting the coupling current I2.

[0074] It should be further explained that if the groove sidewall is not fully fused, the current value of the coupling current I2 should be increased. If the molten pool is too large, especially when welding in a non-flat welding position, the molten pool flows, and the current value of the coupling current I2 should be reduced.

[0075] Specifically, the servo motor 12 includes a photoelectric encoder, which is connected to the servo motor controller. The photoelectric encoder is used to feed back the rotation angle and direction of the servo motor 12 to the servo motor controller.

[0076] Specifically, the photoelectric encoder feeds back the forward or reverse rotation angle A of the motor shaft 121 of the servo motor 12 to the servo motor controller in the form of a digital signal; the servo motor controller transmits the rotation position signal to the synchronous controller, and the synchronous controller obtains the rotation angle A by measuring the digital signal;

[0077] It should be noted that: when the angle A is rotated in the positive direction, A is a positive number; when the angle A is rotated in the reverse direction, A is a negative number;

[0078] The synchronous controller is preset with a reference angle B and a threshold value C. The synchronous controller determines whether the motor shaft 121 of the servo motor 12 has rotated to a preset position according to the formula: |AB|≤C;

[0079] More specifically, if the absolute value of AB is ≤C, the synchronous controller confirms that the motor shaft 121 of the servo motor 12 has rotated to the preset position; and, at this time, the arc is at the side wall of the groove, and the synchronous controller responds to the received rotation position signal and turns off the switch of the coupling power supply, so that the side wall of the groove is fully fused.

[0080] Specifically, the bending angle of the tail end of the curved conductive rod 14 relative to the central axis of the curved conductive rod 14 is 10°; after the absolute value of the rotation angle A is taken, its numerical range is 30°-90°.

[0081] Specifically, the welding power source is one of a TIG power source, a MIG power source, and a SAW power source;

[0082] More specifically, the parameters of the coupling current I2 need to adjust the size of the welding current I1 according to the actual welding effect; the output current of the coupling power supply and the welding power supply are respectively in the form of a constant current and a pulse current, and the output current matching load characteristic is an impedance characteristic, wherein the matching load resistance is 0.1-0.6 ohms.

[0083] This embodiment further provides a narrow gap welding method for controlling welding heat input in a zoned manner, which is applied to the above-mentioned narrow gap welding device. The method comprises the following steps:

[0084] Step S1: Presetting parameter values; presetting welding process parameters on the welding power supply, setting coupling current I2 on the coupling power supply, setting welding current I1 on the welding power supply, and setting swing parameters on the servo motor controller; wherein the positive output electrode of the coupling power supply and the positive power electrode of the welding power supply are connected in parallel to the electrical input terminal of the cable connector 11, and the negative output electrode of the coupling power supply and the negative power electrode of the welding power supply are connected in parallel to the electrical input terminal of the substrate to be welded;

[0085] Step S2: Welding begins. After the welding wire strikes the arc, it begins to swing. The servo motor 12 has a photoelectric encoder for feeding back the rotation angle and direction of the motor shaft 121 of the servo motor 12 to the servo motor controller. The servo motor controller transmits the rotation position signal to the synchronous controller. After the synchronous controller sets the hysteresis parameter, it controls the switch of the coupling power supply according to the rotation position signal. When the welding wire swings to the side wall of the groove, the synchronous controller turns on the switch of the coupling power supply. At this time, the current of the coupling power supply is I2, and the current passing through the arc is I 总 =I1+I2; When the welding wire swings away from the groove side wall, the synchronous controller turns off the switch of the coupling power supply, and the arc current is I 总 =I1;

[0086] Step S3: By adjusting the magnitude of the coupling current I2, the heat input at the groove sidewall is increased without increasing the heat input in the middle of the groove, thereby controlling the weld formation and ensuring the fusion of the sidewalls. When the groove sidewalls are not fully fused, the current value of the coupling current I2 is increased; when the groove sidewalls are fully fused, the current value of the coupling current I2 is reduced.

[0087] Specifically, the welding process parameters include current and voltage; the swing parameters include swing angle, swing speed and side wall residence time; the swing angle has a value range of 30°-90°, and the swing speed has a value range of 0° / s-1440° / s.

[0088] The specific implementation process is as follows:

[0089] The base material to be welded is 345R steel with a plate thickness of 60 mm and a groove size of 18-22 mm; the welding current I1 of the welding power supply is set to 200 A, and the wire feeding speed of the welding wire is set to 7.5 m / min; the swing parameters are set as follows: the swing angle is 70°, the swing speed is 120° / s, and the side wall residence time is 0.1 s; the parameters of the coupling power supply are a pulse frequency of 15 kHz and a coupling current I2 of 50 A (using average current).

[0090] When the arc is in the middle of the groove, the current I 总 About 200A; when the arc is on the side wall of the groove, the circuit of the coupling power supply is turned on, and the arc current I 总 It is the sum of welding current I1 and coupling current I2. At this time, the arc current is I 总 =250A, which significantly increases the heat input to the groove sidewalls, while the heat input to the weld center remains unchanged.

[0091] Example 2

[0092] This embodiment also provides a narrow gap welding device with zoned control of welding heat input. Features not explained in this embodiment can be explained in Example 1 and will not be described in detail here. The difference between this embodiment and Example 1 is:

[0093] The base material to be welded was 690 high-strength steel with a thickness of 30 mm and a groove size of 10-12 mm. In this embodiment, a vertical welding position was used. Conventional welding methods would easily cause the molten pool to flow and the weld to be poorly formed. The welding power supply's welding current I1 was set to 140 A, and the wire feed speed was set to 5 m / min. The swing parameters were set to: swing angle of 35°, swing speed of 120° / s, and sidewall dwell time of 0.2 s. The coupling power supply parameters were a pulse frequency of 100 Hz and a coupling current I2 of 80 A (using average current).

[0094] When the arc is in the middle of the groove, the current I 总 About 140A; when the arc is on the side wall of the groove, the circuit of the coupling power supply is turned on, and the arc current I 总 It is the sum of welding current I1 and coupling current I2. At this time, the arc current is I 总=220A, so it can significantly improve the heat input of the groove side wall. Due to the high temperature of the groove side wall, the molten pool metal wets and spreads on the groove side wall, and the heat input in the center of the weld is not increased. Moreover, due to the low wire feeding speed, there is no molten pool flow and no bulge in the middle of the weld, which solves the problem of vertical welding of high-strength steel thick plates.

[0095] Based on the disclosure and teachings of the above description, those skilled in the art may also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and modifications and variations of the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although certain specific terms are used in this description, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims

1. A narrow gap welding device with zoned control of welding heat input, comprising an oscillating arc welding gun and a welding wire for welding a narrow gap groove of a substrate to be welded, characterized in that: The swing arc welding gun includes a cable connector, a servo motor, a hollow reducer, a curved conductive rod and a conductive nozzle, wherein the servo motor is drivingly connected to the hollow reducer, and the curved conductive rod is drivingly connected to the hollow reducer; The device further comprises a power supply circuit, a servo motor controller and a synchronous controller, wherein the power supply circuit comprises a coupling power supply and a welding power supply; the servo motor is electrically connected to the servo motor controller, the servo motor controller is electrically connected to the synchronous controller, and the synchronous controller is electrically connected to the coupling power supply; the coupling power supply comprises an output positive electrode and an output negative electrode; the welding power supply comprises a power supply positive electrode and a power supply negative electrode; the output positive electrode and the power supply positive electrode are connected in parallel to the electrical input end of the cable connector, and the output negative electrode and the power supply negative electrode are connected in parallel to the electrical input end of the base material to be welded; The servo motor controller sends a pulse signal to control the servo motor to rotate forward or reverse by an angle A; the servo motor indirectly drives the conductive nozzle to rotate forward or reverse by an angle A around the central axis of the curved conductive rod through a hollow reducer, thereby driving the arc to swing forward or reverse inside the narrow gap groove; The servo motor controller is configured to generate a rotational position signal and transmit the signal to the synchronization controller, wherein the rotational position signal is used to represent the rotational position of the servo motor; The synchronous controller performs synchronous control operations on the coupled power switches in response to the received rotational position signals to dynamically turn on or off the coupled power according to the position area of ​​the arc, thereby achieving zoned control of the arc heat input during narrow gap welding.

2. The narrow gap welding device according to claim 1, characterized in that: A first high-power diode is installed between the positive pole of the power supply and the electrical input end of the cable connector; a second high-power diode is installed between the positive output pole and the electrical input end of the cable connector; wherein the positive pole of the first high-power diode is connected to the positive pole of the power supply, and the positive pole of the second high-power diode is connected to the positive output pole.

3. The narrow gap welding device according to claim 1 or 2, characterized in that: The output welding current I1 of the welding power supply; When the welding wire swings away from the groove side wall, the synchronous controller disconnects the coupling power supply, and the total arc current is I 总 =I1; When the welding wire swings to the side wall of the groove, the synchronous controller turns on the coupling power supply. At this time, the output coupling current of the coupling power supply is I2, and the total current of the arc is I 总 =I1+I2.

4. The narrow gap welding device according to claim 3, characterized in that: The parameters of the coupling current I2 need to adjust the magnitude of the welding current I1 according to the actual welding effect; the output current of the coupling power supply and the welding power supply are respectively in the form of a constant current or a pulse current, and the output current matching load characteristic is an impedance characteristic, wherein the matching load resistance is 0.1-0.6 ohms; The actual welding effect includes whether the groove sidewall is fully fused or not; when the groove sidewall is not fully fused, the current value of the coupling current I2 is increased; when the groove sidewall is fully fused, the current value of the coupling current I2 is reduced.

5. The narrow gap welding device according to claim 1, characterized in that: The welding power source is one of a TIG power source, a MIG power source and a SAW power source.

6. The narrow gap welding device according to claim 1, characterized in that: The servo motor includes a photoelectric encoder connected to the servo motor controller. The photoelectric encoder is used to feed back the rotation angle and direction of the servo motor to the servo motor controller.

7. The narrow gap welding device according to claim 6, characterized in that: The photoelectric encoder feeds back the forward or reverse rotation angle A of the motor shaft of the servo motor to the servo motor controller in the form of a digital signal; the servo motor controller transmits the rotation position signal to the synchronous controller, and the synchronous controller obtains the rotation angle A by measuring the digital signal; A comparison angle B and a threshold value C are preset in the synchronous controller. The synchronous controller determines whether the motor shaft of the servo motor has rotated to a preset position according to the formula: |AB|≤C.

8. The narrow gap welding device according to claim 1 or 7, characterized in that: The bending angle of the tail end of the bent conductive rod relative to the central axis of the bent conductive rod is 10°; after the absolute value of the rotation angle A is taken, its numerical range is 30°-90°.

9. A narrow gap welding method for controlling welding heat input in different zones, characterized in that: Applied to the narrow gap welding device according to any one of claims 1 to 8, the method comprises the following steps: Step S1: Presetting parameter values; presetting welding process parameters on the welding power supply, setting coupling current I2 on the coupling power supply, setting welding current I1 on the welding power supply, and setting swing parameters on the servo motor controller; wherein the positive output electrode of the coupling power supply and the positive power electrode of the welding power supply are connected in parallel to the electrical input end of the cable connector, and the negative output electrode of the coupling power supply and the negative power electrode of the welding power supply are connected in parallel to the electrical input end of the base material to be welded; Step S2: Welding begins. After the welding wire strikes the arc, it begins to swing. The servo motor has a photoelectric encoder for feeding back the rotation angle and direction of the servo motor shaft to the servo motor controller. The servo motor controller transmits the rotation position signal to the synchronous controller. After the synchronous controller sets the hysteresis parameter, it controls the switch of the coupling power supply according to the rotation position signal. When the welding wire swings to the side wall of the groove, the synchronous controller turns on the switch of the coupling power supply. At this time, the current of the coupling power supply is I2, and the current passing through the arc is I 总 =I1+I2; When the welding wire swings away from the groove side wall, the synchronous controller turns off the switch of the coupling power supply, and the arc current is I 总 =I1; Step S3: By adjusting the magnitude of the coupling current I2, the heat input at the groove sidewall is increased without increasing the heat input in the middle of the groove; when the groove sidewall is not fully fused, the current value of the coupling current I2 is increased; when the groove sidewall is fully fused, the current value of the coupling current I2 is reduced.

10. The narrow gap welding method according to claim 9, characterized in that: The welding process parameters include current and voltage; the swing parameters include swing angle, swing speed and side wall residence time; the swing angle has a value range of 30°-90°, and the swing speed has a value range of 0° / s-1440° / s.

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