A magnetic field assisted welding system

Abstract

The present application relates to a kind of magnetic field auxiliary welding systems, including excitation power supply and enhanced magnetic field generating device, excitation power supply main circuit topology is based on PFC circuit, LLC resonant conversion circuit and modulated output circuit, can adjust parameter according to welding scene, output different forms such as direct current, pulse and alternating current etc. Excitation current into enhanced magnetic field generating device.The enhanced magnetic field generating device includes solenoid, magnetic conducting rod, top connecting plate and sleeve shield, the solenoid is coaxially assembled with welding torch, adjusts the installation mode of magnetic conducting rod and can produce multiple forms of magnetic field in effective welding area.The present application generates directional Lorentz force in welding arc and molten pool by applying magnetic field, effectively reduces undercut and magnetic blow, plays the role of refining grain, promoting weld metal fusion etc., is suitable for various welding production scenes such as dissimilar metal, all-position and medium plate.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of welding technology, in particular to a magnetic field assisted welding system. BACKGROUND

[0002] In the welding process, the application of magnetic field can intervene the shape of electric arc and the flow of molten pool liquid metal due to the action of Lorentz force, so that the weld forming changes accordingly, and a joint with better performance is obtained. At the same time, it can also improve the problems such as low molten pool efficiency, magnetic deflection of electric arc, shallow weld penetration and slow welding speed. In recent years, magnetic control assisted welding technology has been widely used because of the above advantages. The magnetic control assisted welding system mainly includes excitation power supply and magnetic field generating device, but there are the following problems to be solved in the actual application of the two key devices:

[0003] 1. Most of the existing excitation power supply can only output single direct current or alternating current, and the application scene is limited. The static magnetic field generated under the action of direct current can realize full position and multi-angle welding through the action of Lorentz force, and can also improve the magnetic deflection problem in dissimilar metal welding, but it cannot play the stirring role of magnetic control assisted welding on this basis; the alternating magnetic field generated under the action of alternating current will cause the electric arc to swing violently if the alternating current frequency is too high, which will affect the weld forming, so the excitation power supply is suitable for working under low frequency condition. In order to meet the low frequency working condition, the device volume is relatively large, which is not conducive to the integration of the welding system.

[0004] 2. When welding medium-thick plates, the spatial distribution of magnetic lines is unreasonable due to the design problem of the magnetic field generating device and the shielding effect of the workpiece to be welded, and the magnetic field strength near the effective welding area (tungsten needle tip of welding gun) is low. The current solution is to increase the excitation current or increase the number of turns of the excitation coil to increase the magnetic field strength, but the actual improvement effect is not obvious. Increasing the excitation current will cause the excitation coil to overheat, which not only wastes electric energy but also requires the addition of cooling and heat dissipation devices, increasing the manufacturing cost of the magnetic field generating device. At the same time, under alternating current condition, increasing the number of turns of the excitation coil will cause the inductance to be too large, the excitation current to decrease, and the increase of the magnetic field strength to be hindered.

[0005] The above problems limit the application scene of magnetic control assisted welding, so it is crucial to develop a magnetic control assisted welding system that can output multiple forms of electric energy and be suitable for various application scenes. SUMMARY

[0006] In view of the problems in the prior art, the purpose of the present application is to provide a magnetic field assisted welding system that can output multiple forms of electric energy and be suitable for various application scenes.

[0007] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0008] A magnetic field assisted welding system, comprising an excitation power supply and an enhanced magnetic field generating device, a welding torch and a welding power supply;

[0009] The main circuit topology of the excitation power supply comprises a PFC circuit, an LLC resonant conversion circuit and a modulation output circuit connected in sequence;

[0010] The PFC circuit is used to convert 220V AC power into pulsating DC power, and then boost the output of high-voltage DC power, while making the current in phase with the input voltage;

[0011] The LLC resonant conversion circuit is used to convert high-voltage DC power into high-voltage square-wave AC power, and then into low-voltage square-wave AC power on the secondary side, and then convert it into smooth DC power after rectification and filtering;

[0012] The modulation output circuit is used to convert the smooth DC power into adjustable excitation current according to the preset output waveform requirements and input it into the enhanced magnetic field generating device;

[0013] The enhanced magnetic field generating device is coaxially assembled with the welding torch and placed above the workpiece to be welded, and is used to generate a longitudinal magnetic field, a magnetic field perpendicular to the welding direction or a magnetic field parallel to the welding direction in the effective welding area;

[0014] The welding power supply is connected to the welding torch at one end and to the workpiece to be welded at the other end.

[0015] Further, the PFC circuit comprises a rectifier bridge composed of diodes D1, D2, D3 and D4, and a Boost voltage boosting module composed of a boost inductor L1, a fast recovery diode D5, a power switch tube Q1 and a capacitor C1. The rectifier bridge is used to rectify the 220V AC power and output pulsating DC power to the Boost voltage boosting module. The Boost voltage boosting module is used to output high-voltage bus DC to the LLC resonant conversion circuit under the control of a duty cycle signal, while making the boost inductor L1 current in phase with the input voltage.

[0016] Further, the LLC resonant conversion circuit comprises a resonant inverter module and a rectification and filtering module connected in sequence. The resonant inverter module comprises power switch tubes Q2, Q3, Q4 and Q5, and their respective parallel capacitors C2, C3, C4 and C5, as well as a resonant inductor L r , a resonant capacitor C r , a transformer excitation inductor L m and a transformer T. The rectification and filtering module comprises Schottky diodes D6 and D7, a power inductor L2 and a filter capacitor C6. The resonant inverter module is used to convert high-voltage bus DC power into high-voltage square-wave AC power, and then convert it into low-voltage square-wave AC power on the secondary side through the transformer T. The rectification and filtering module is used to convert the low-voltage square-wave AC power into smooth DC power for the modulation output circuit.

[0017] Further, the modulation output circuit comprises an inverter bridge composed of power switch tubes Q6, Q7, Q8 and Q9 and a filter module composed of an inductor L3 and a capacitor C7, and is used for converting low-voltage direct current into adjustable excitation current and inputting the adjustable excitation current into the enhanced magnetic field generating device.

[0018] Further, the enhanced magnetic field generating device comprises a solenoid, a magnetic conducting rod, a top connecting plate and a sleeve shield; the solenoid is coaxially arranged with the welding gun, the solenoid is externally wound with an enameled wire, the enameled wire is connected to an output end of the modulation output circuit, the magnetic conducting rod is connected to the solenoid and used for forming a longitudinal magnetic field, a magnetic field perpendicular to a welding direction or a magnetic field parallel to the welding direction in an effective welding area, the top connecting plate is connected to an upper end of the solenoid, and the sleeve shield is sleeved with the solenoid.

[0019] Further, the magnetic conducting rod comprises a first magnetic conducting rod, a top end of the first magnetic conducting rod is located in a middle part of the solenoid, a bottom end of the first magnetic conducting rod is located in a bottom part of the solenoid, and the first magnetic conducting rod is installed in the solenoid in parallel to the welding direction and used for forming the longitudinal magnetic field near the effective welding area.

[0020] Further, the magnetic conducting rod comprises a first magnetic conducting rod and a second magnetic conducting rod, the first magnetic conducting rod and the second magnetic conducting rod are respectively installed in two sides of the solenoid in perpendicular to the welding direction and used for generating the magnetic field perpendicular to the welding direction near the effective welding area.

[0021] Further, the magnetic conducting rod comprises a first magnetic conducting rod and a second magnetic conducting rod, the first magnetic conducting rod and the second magnetic conducting rod are respectively installed in two sides of the solenoid in parallel to the welding direction and used for generating the magnetic field parallel to the welding direction near the effective welding area.

[0022] Further, a top end of the second magnetic conducting rod is located in a top part of the solenoid, and a bottom end of the second magnetic conducting rod is located in a bottom part of the solenoid.

[0023] Further, the sleeve shield is provided with a slot opening for leading out the second magnetic conducting rod and the enameled wire.

[0024] Overall, the present application has the following advantages:

[0025] 1. In the process of magnetic control auxiliary welding, the output current form of the excitation power supply needs to be adjusted according to different welding materials and welding environments, and most of the existing excitation power supplies can only output a single current. In view of this, a new main circuit topology is adopted in the present application, which can realize various current waveforms such as direct current, pulse and alternating current, can be suitable for various application scenarios such as dissimilar metals, all-position and medium-thick plate narrow gap, and can realize small size and easy integration with the welding machine in low-frequency alternating current working condition.

[0026] 2. In actual production, especially in welding thick plate, the existing magnetic field generating device magnetic circuit design is unreasonable, the magnetic field is shielded by the structure of the workpiece to be welded to different degrees, and the magnetic field cannot act on the effective welding area. In view of this, the application optimizes the magnetic circuit through the enhanced magnetic field generating device, and the generated magnetic field acts on the effective welding area, and different direction magnetic field can be generated. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a schematic diagram of a magnetic control auxiliary welding system of the application;

[0028] Figure 2 It is a main circuit topology structure diagram of the excitation power supply of the application;

[0029] Figure 3 It is a structure diagram of the enhanced magnetic field generating device of the application;

[0030] Figure 4 It is a schematic diagram of the installation mode one of the enhanced magnetic field generating device of the application;

[0031] Figure 5 It is a schematic diagram of the installation mode two of the enhanced magnetic field generating device of the application;

[0032] Figure 6 It is a schematic diagram of the installation mode three of the enhanced magnetic field generating device of the application;

[0033] Figure 7 It is an arc and molten pool schematic diagram when welding dissimilar metals;

[0034] Figure 8 It is a direct current pulse electric output waveform diagram in the embodiment of the application;

[0035] Figure 9 It is an arc and molten pool schematic diagram in the embodiment of the application;

[0036] Figure 10 It is a sine alternating current output waveform diagram in the embodiment of the application;

[0037] In the figure:

[0038] 1-excitation power supply, 2-welding gun, 3-enhanced magnetic field generating device, 31-solenoid, 32-first magnetic conducting rod, 33-second magnetic conducting rod, 34-sleeve shield, 35-top connecting plate, 4-welding power supply, 5-workpiece to be welded. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the present application clearer, further explanation will be given below in connection with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in the embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0040] Please refer to Figure 1 , the embodiment of the present application provides a magnetic control auxiliary welding system, including excitation power supply 1, welding torch 2, enhanced magnetic field generating device 3 and welding power supply 4. The front end of the excitation power supply 1 is connected with single-phase alternating current network, the rear end of the excitation power supply 1 is connected with the enameled wire in the enhanced magnetic field generating device 3 through wire, the enhanced magnetic field generating device 3 is coaxially assembled with the welding torch 2, the welding torch 2 and the workpiece to be welded 5 are respectively connected with the negative and positive of the welding power supply 4 to form a conduction loop.

[0041] The main circuit topology of the excitation power supply 1 is shown in Figure 2 , the main circuit topology includes PFC circuit, LLC resonant conversion circuit and modulated output circuit.

[0042] The PFC circuit includes rectifier bridge and Boost module, the rectifier bridge is composed of diodes D1, D2, D3 and D4, the Boost module is composed of boost inductor L1, fast recovery diode D5, power switch tube Q1 and capacitor C1. The input end of the rectifier bridge is connected with 220V alternating current, one way of the rectifier bridge output end is connected with one end of the capacitor C1 through the boost inductor L1 and the fast recovery diode D5, the second way is connected with the ground through the power switch tube Q1, the other end of the capacitor C1 is connected with the ground. After the 220V alternating current passes through the rectifier bridge, the output is pulsating direct current, and under the control of the duty cycle signal, the Boost module outputs high voltage bus direct current to the LLC resonant conversion circuit, and at the same time, the boost inductor L1 current and the input voltage are kept in phase.

[0043] The LLC resonant conversion circuit includes resonant inverter module and rectification filter module connected in sequence. The resonant inverter module includes power switch tubes Q2, Q3, Q4, Q5 and their respective parallel capacitors C2, C3, C4, C5, resonant inductor L r , resonant capacitor C r , transformer excitation inductor L m and transformer T, the power switch tubes Q2, Q3, Q4, Q5 and their respective parallel capacitors C2, C3, C4, C5 constitute a full-bridge inverter circuit, one end of the resonant inductor L r is connected between the power switch tube Q2 and the power switch tube Q3, the other end is connected with the same name end of the transformer T input winding, the different name end of the transformer T input winding is connected with the resonant capacitor Cr The other end of the resonant capacitor C r The other end of the resonant capacitor C m The other end of the resonant capacitor C s The other end of the resonant capacitor C r The other end of the resonant capacitor C r The other end of the resonant capacitor C r The other end of the resonant capacitor C m The other end of the resonant capacitor C The other end of the resonant capacitor C

[0044] The other end of the resonant capacitor C The other end of the resonant capacitor C

[0045] The other end of the resonant capacitor C The other end of the resonant capacitor C

[0046] Further, the power generation process of the excitation power supply 1 of the present application is as follows: Further, the power generation process of the excitation power supply 1 of the present application is as follows:

[0047] The rectifier bridge converts 220V AC into pulsating DC, which is input into the Boost module to output high-voltage DC, and then the LLC resonant inverter module converts the high-voltage DC into an AC square wave on the primary coil of the high-frequency transformer, the transformer couples the square wave to the secondary output end, the rectifier filter module converts the AC square wave on the secondary output end of the transformer into smooth DC, and the modulation module converts the DC into a parameter-adjustable excitation current input into the enameled wire coil of the enhanced magnetic field generating device 3 according to the preset output waveform requirement.

[0048] As shown in Figure 3 , the enhanced magnetic field generating device 3 comprises a solenoid 31, a first magnetic conducting rod 32, a second magnetic conducting rod 33, a sleeve shield 34, and a top connecting plate 35.

[0049] The solenoid 31 is coaxially assembled with the welding gun 2.

[0050] For the magnetic field generating device, there are various arrangement forms according to actual production scenes, and one of the prior arts adopts two sets of symmetrically arranged L-shaped magnetic cores to generate a magnetic field, and the enameled wire coils are wound on the two sets of magnetic cores to generate two forms of magnetic fields parallel or perpendicular to the welding direction, but during use, more coils are used, and the coils are easily connected incorrectly during adjustment of the magnetic field direction, thereby increasing the workload of debugging and testing.

[0051] The application optimizes the magnetic circuit by additionally arranging the magnetic conducting rods to replace the magnetic cores, the magnetic field generated by the enameled wire coil of the solenoid 31 acts on the effective welding area after being constrained by the magnetic conducting rods, the magnetic conducting rods can generate three different forms of magnetic fields by optional arrangement, which simplifies the operation steps and is beneficial to the integration of the magnetic control auxiliary welding system.

[0052] Optionally, the magnetic conducting rods have three installation modes as follows:

[0053] Mode one: as shown in Figure 4 , only the first magnetic conducting rod 32 is installed in the installation slot on the solenoid 31 along the parallel direction to the welding direction (Y-axis direction), and a longitudinal magnetic field can be formed near the effective welding area;

[0054] Mode two: as shown in Figure 5 , the first magnetic conducting rod 32 and the second magnetic conducting rod 33 are respectively installed in the installation slots of the solenoid 31 along the perpendicular direction to the welding direction (X-axis direction), and the ends of the magnetic conducting rods can generate a magnetic field perpendicular to the welding direction near the effective welding area;

[0055] Mode three: as shown in Figure 6 , the first magnetic conducting rod 32 and the second magnetic conducting rod 33 are respectively installed in the installation slots of the solenoid 31 along the parallel direction to the welding direction (Y-axis direction), and the ends of the magnetic conducting rods can generate a magnetic field parallel to the welding direction near the effective welding area.

[0056] The top connecting plate 35 is threadedly connected to the upper end of the solenoid 31, and the sleeve shield 34 is threadedly connected to the side of the top connecting plate 35, and the sleeve shield 34 is provided with a slot opening on the side to lead out the second magnetic conducting rod 33 and the enameled wire.

[0057] The embodiment mainly aims at welding dissimilar metal materials, and particularly relates to welding of ferrite base material and austenite base material. In actual welding, the electromagnetic properties of the two metal materials are quite different, which can cause deflection or deviation of the welding arc during the welding process, thereby damaging the forming performance of the welded joint. Figure 7 As shown in the figure, when welding the ferrite base material and the austenite base material, if the above-mentioned magnetic control auxiliary welding system is not used, the arc will deflect to the side of the ferrite base material during the welding process, and obvious undercut will appear in the weld near the austenite base material area after welding.

[0058] The embodiment adds a magnetic field auxiliary welding system before the welding starts, as shown in the figure. Figure 1 As shown in the figure, the excitation power supply 1 outputs a direct current pulse current waveform, as shown in the figure. Figure 8 The current flows into the solenoid 31 from the upper end (Z-axis positive direction) and flows out from the lower end (Z-axis negative direction) of the solenoid 31. The first magnetic conducting rod 32 and the second magnetic conducting rod 33 of the enhanced magnetic field generating device 3 are installed in mode three, the first magnetic conducting rod 32 is magnetized as N pole, and the second magnetic conducting rod 33 is magnetized as S pole, and a magnetic field along the Y-axis negative direction is generated in the effective welding area. The arc and the molten pool during the welding process of the embodiment are as shown in the figure. Figure 9 At this time, according to the left-hand rule, it can be determined that the Lorentz force F on the arc is along the X-axis positive direction, and the Lorentz force in this direction will inhibit the deflection of the arc to the ferrite base material, thereby reducing the undercut and un-melted defects, and at the same time, the changing magnetic field generated by the direct current pulse has a stirring effect on the molten pool metal, which can promote the fusion of dissimilar metals and is beneficial to the uniform distribution of the weld composition.

[0059] Adjust the current parameters of the excitation power supply 1, and the embodiment can also be applied in all-position welding, and the arc and the molten pool are affected by the Lorentz force, which effectively inhibits the downward flow of the molten pool metal during all-position welding.

[0060] The present application can also be applied in the welding of medium-thick plates, and the excitation power supply 1 outputs a sinusoidal alternating current, as shown in the figure. Figure 10 The first magnetic conducting rod 32 and the second magnetic conducting rod 33 of the enhanced magnetic field generating device 3 are installed in mode three, and an alternating magnetic field is generated in the effective welding area through the optimization of the magnetic circuit, which solves the problem that the magnetic field is shielded to different degrees due to the structure of the workpiece. At the same time, under the action of the alternating magnetic field, the welding arc swings back and forth, which has a stirring effect on the molten pool, and the problem of un-melted side wall is well solved, and the purpose of refining the grains is achieved.

[0061] The magnetic control auxiliary welding system provided by the application mainly has the following beneficial effects:

[0062] 1. In the process of magnetic control auxiliary welding, the output current form of the excitation power supply 1 needs to be adjusted according to different welding materials and welding environments, and most existing excitation power supplies 1 can only output single current. In view of this, a new main circuit topology is adopted in the application, which can realize various current waveforms such as direct current, pulse and alternating current, can be suitable for various application scenarios such as dissimilar metals, all-position and medium-thick plate narrow gap, and realizes small size in low-frequency alternating current working condition, and is easy to realize integrated integration with the welding machine.

[0063] 2. In actual production, especially when welding medium-thick plate materials, the existing magnetic field generating device magnetic circuit design is unreasonable, the magnetic field is shielded to different degrees by the structure of the workpiece to be welded, and the magnetic field cannot act on the effective welding area. In view of this, the magnetic circuit is optimized by adding a magnetic conducting rod, the magnetic field generated by the enameled coil acts on the effective welding area after being constrained by the magnetic conducting rod, and the magnetic conducting rod can generate magnetic fields in different directions by being selected.

[0064] The above embodiments are the preferred embodiments of the application, but the embodiments of the application are not limited by the above embodiments, and any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principles of the application shall be equivalent replacement modes and shall be included in the protection scope of the application.

Claims

1. A magnetic field assisted welding system, characterized in that: It includes an excitation power supply and an enhanced magnetic field generating device, a welding gun and a welding power supply; The main circuit topology of the excitation power supply includes a PFC circuit, an LLC resonant conversion circuit and a modulation output circuit connected in sequence; The PFC circuit is used to convert 220V AC power into pulsating DC power, and then boost the output high-voltage DC power while making the current in phase with the input voltage; The LLC resonant converter circuit is used to convert high-voltage DC power into high-voltage square-wave AC power, and then into secondary-side low-voltage square-wave AC power, which is then converted into smooth DC power after rectification and filtering. The modulation output circuit is used to convert the smooth direct current into an excitation current with adjustable parameters according to the preset output waveform requirements and input it into the enhanced magnetic field generating device; The enhanced magnetic field generating device is coaxially assembled with the welding gun and placed above the workpiece to be welded, and is used to generate a longitudinal magnetic field, a magnetic field perpendicular to the welding direction, or a magnetic field parallel to the welding direction in the effective welding area; One end of the welding power supply is connected to the welding gun, and the other end is used to connect to the workpiece to be welded; The PFC circuit includes a rectifier bridge composed of diodes D1, D2, D3, and D4, and a Boost boost module composed of a boost inductor L1, a fast recovery diode D5, a power switch tube Q1, and a capacitor C1. The rectifier bridge is used to rectify the 220V AC power and output pulsating DC power to the Boost boost module. The Boost boost module is used to output high-voltage bus DC to the LLC resonant conversion circuit under the control of the duty cycle signal, while keeping the current of the boost inductor L1 in phase with the input voltage.

2. The magnetic field assisted welding system according to claim 1, characterized in that: The LLC resonant conversion circuit includes a resonant inverter module and a rectifier filter module connected in sequence. The resonant inverter module includes power switches Q2, Q3, Q4, Q5 and their respective parallel capacitors C2, C3, C4, C5 and a resonant inductor L. r , resonant capacitor C r , transformer excitation inductance L m As well as transformer T, the rectifier and filter module includes Schottky diodes D6 and D7, power inductor L2 and filter capacitor C6. The resonant inverter module is used to convert the high-voltage bus DC power into high-voltage square wave AC power and then convert it into secondary side low-voltage square wave AC power through transformer T. The rectifier and filter module is used to convert the low-voltage square wave AC power into smooth DC power for the modulation output circuit.

3. The magnetic field assisted welding system according to claim 1, characterized in that: The modulation output circuit includes an inverter bridge composed of power switch tubes Q6, Q7, Q8, and Q9, and a filter module composed of inductor L3 and capacitor C7. The modulation output circuit is used to convert low-voltage direct current into an excitation current with adjustable parameters and input it into the enhanced magnetic field generating device.

4. The magnetic field assisted welding system according to claim 1, characterized in that: The enhanced magnetic field generating device includes a solenoid, a magnetic rod, a top connecting plate and a sleeve shielding cover; the solenoid is coaxially assembled with the welding gun, and the outside of the solenoid is wound with enameled wire, which is connected to the output end of the modulation output circuit. The magnetic rod is clamped on the solenoid to form a longitudinal magnetic field, a magnetic field perpendicular to the welding direction or a magnetic field parallel to the welding direction in the effective welding area. The top connecting plate is connected to the upper end of the solenoid, and the sleeve shielding cover is sleeved on the outside of the solenoid.

5. The magnetic field assisted welding system according to claim 4, characterized in that: The magnetic rod includes a first magnetic rod, the top end of the first magnetic rod is located in the middle of the solenoid, the bottom end of the first magnetic rod is located at the bottom of the solenoid, and the first magnetic rod is installed on the solenoid parallel to the welding direction to form a longitudinal magnetic field near the effective welding area.

6. The magnetic field assisted welding system according to claim 4, characterized in that: The magnetic rods include a first magnetic rod and a second magnetic rod, which are respectively installed on both sides of the solenoid along a direction perpendicular to the welding direction, and are used to generate a magnetic field perpendicular to the welding direction near the effective welding area.

7. The magnetic field assisted welding system according to claim 4, characterized in that: The magnetic rods include a first magnetic rod and a second magnetic rod, which are respectively installed on both sides of the solenoid parallel to the welding direction, and are used to generate a magnetic field parallel to the welding direction near the effective welding area.

8. A magnetic field assisted welding system according to claim 6 or 7, characterized in that: The top end of the second magnetic conductive rod is located at the top of the solenoid, and the bottom end of the second magnetic conductive rod is located at the bottom of the solenoid.

9. The magnetic field assisted welding system according to claim 8, characterized in that: The sleeve shielding cover is provided with a slotted opening for leading out the second magnetic conductive rod and the enameled wire.

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