Microwave-resistance combined fusion welding device with low welding pressure

Abstract

The utility model belongs to the technical field of welding of thermoplastic polymer materials, composite materials, ceramics, metal and the like, and relates to a low-welding-pressure microwave-resistance combined fusion welding device which comprises a welding head system, an operation platform and a robot system. The robot system is located on one side of the operation platform, and a to-be-welded part is placed on the operation platform. The welding head system is designed according to the characteristic that polar molecular materials generate vibration under the action of a microwave field and then generate heat, the welding head system can correct and fix the composite material parts when welding the large-size composite material parts, the function of providing clamping force is achieved, enough welding pre-pressure and cooling pressure maintaining time are provided in the welding process, and the welding head system can be used for welding the large-size composite material parts. And the welding efficiency and the welding quality are effectively improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of welding of thermoplastic polymer materials, composite materials, ceramics, metals, etc., and relates to a microwave-resistance combined melting welding device with low welding pressure. The device is designed based on the characteristics that polar molecular materials generate vibration and then generate heat under the action of a microwave field. The welding head system can correct and fix composite material parts when welding large-size composite material parts, and provide a clamping force function. During the welding process, sufficient welding pre-pressure and cooling pressure holding time are provided, effectively improving welding efficiency and welding quality. Background Art

[0002] The development of resistance welding technology still has some problems that cannot be solved temporarily, such as 1) low welding efficiency; 2) heating elements on the welding interface, which affects the welding strength and corrosion resistance; 3) the pressure device is difficult to use in a lightweight manner; 4) resistance welding has high requirements for the processing accuracy of the welded parts.

[0003] Patent: A dual robot-assisted resistance welding device for thermoplastic composite materials (CN212219341U). Patent: Robot-assisted continuous resistance welding equipment for thermoplastic materials (CN212422216U). The continuous pressurizing modules used in the robot-assisted resistance welding equipment for thermoplastic materials in these two patents are both roller-type. Welding experiments have verified that the roller-type pressurizing equipment has uneven pressure in the welding area. The roller pressure is only limited to the line where the roller contacts the material to be welded. In addition, since a certain pressure holding time is required after welding, it means that the pressurized roller needs to keep the welding position still until the thermoplastic material is completely solidified. The above problems lead to other positions being unable to be welded due to insufficient welding pressure, such as Figures 9(a) to 9(c) shown.

[0004] For the connection of thermoplastic parts to be welded with insufficient preparation precision, such as warping deformation during the preparation of the parts to be welded, Figure 10(a) to Figure 10(b) As shown, when the thickness and rigidity of the welded parts are large, the fitting gap caused by the warping deformation cannot complete the fusion welding of the welded parts at room temperature.

[0005] For welding areas of the parts to be welded, there is an interference fit or a large clearance fit, such as Figure 11(a) to Figure 11(d) As shown: when the welding position of the parts to be welded has an assembly relationship as shown in the figure, such as when the assembly relationship between the parts to be welded is an interference fit, the welding film and the heating element cannot be placed in the welding area. If the assembly relationship between the parts to be welded is a large gap fit, and even if the welding film and the heating element are placed, there is still a large gap at the weld position, which will cause the welding pressure to fail to meet the requirements or the pressure to be uneven during the resistance welding process.

[0006] In the traditional resistance welding process of thermoplastic parts to be welded, the welding interface of the parts to be welded needs to be tightly fitted together, and the product precision of the parts to be welded is high. If there is a gap at the welding interface of the parts to be welded, the welding strength cannot be guaranteed. If the welding interface of the parts to be welded is an interference fit, the heating element, welding film, etc. cannot be placed at the welding interface, and resistance welding cannot be completed.

[0007] In addition, the maximum length of a single resistance welding is limited by the edge effect, and large sizes cannot be welded at one time. In addition, resistance welding requires a relatively high welding pressure. How to achieve efficient welding of large-sized polymer materials and composite materials has become a difficult problem internationally at this stage. Utility Model Content

[0008] In response to the defects caused by the above-mentioned welding equipment or connection methods, the utility model proposes a microwave-resistance combined fusion welding equipment with low welding pressure based on the characteristics that polar molecular materials vibrate and then generate heat under the action of a microwave field. When welding large-sized composite material parts, the equipment can fix the composite material parts and provide clamping force. During the welding process, the equipment can provide sufficient welding pre-pressure and cooling and holding time, thereby effectively improving welding efficiency and welding quality.

[0009] The technical solution of the utility model is:

[0010] A microwave-resistance combined melting welding device with low welding pressure includes a welding head system 1, an operating platform 2 and a robot system 4. The welding head system 1 is installed on the execution end of the robot system 4, and the robot system 4 is located on one side of the operating platform 2. The workpiece 3 to be welded is placed on the operating platform 2.

[0011] The welding head system 1 includes a flat plate welding head system 12 and a stiffener beam welding head system 13, which are arranged in parallel; the parts to be welded 3 include flat plate parts to be welded and stiffener beam parts to be welded, the flat plate welding head system 12 is used for welding between a flat plate part 19 to be welded and a flat plate part 2 11 to be welded, and the stiffener beam welding head system 13 is used for welding between a stiffener beam part 10 to be welded and a flat plate part 9 to be welded.

[0012] The flat plate welding head system 12 includes a welding head system housing 14, a resistance welding system 18, a pressurized motor 17 and a microwave heating system 19; the welding head system housing 14 is a box structure, wherein the lower part of the two opposite surfaces and the bottom surface are provided with openings that are consistent with the protruding shape of the welding position of the welded part 3 to be welded, so as to avoid interference with the welded part 3, and the welding head system housing 14 is placed above the welded part 3 by the robot system 4, the bottom of the welding head system housing 14 is in contact with the operating platform 2, and the openings of the two opposite surfaces of the welding head system housing 14 are in contact with the outer surface of the welded part 3 to be welded, so that a sealed space is formed inside the welding head system housing 14 to prevent microwaves from escaping; the microwave heating system 19 includes a microwave source 15, a power amplifier 16, two point-focusing microwave antennas 21 and a flexible waveguide 20; the microwave source 15 and the power amplifier 16 are installed on the upper surface of the welding head system housing 14; an opening is provided on the upper surface of the welding head system housing 14 for the flexible waveguide 20 to pass through; the power amplifier 16, one end of which is connected to the microwave source 15 The other end is connected to two point-focusing microwave antennas 21, which are fixed on the inner wall of the welding head system housing 14 and arranged relative to each other. The two point-focusing microwave antennas 21 enclose the welding position; the microwaves emitted by the microwave source 15 are guided to the two point-focusing microwave antennas 21 through the flexible waveguide 20 after passing through the power amplifier 16. Since there is a microwave focusing lens inside the point-focusing microwave antenna 21, the microwaves can be focused on the welding position, and the welding position is heated by the microwave heating system 19; the resistance welding system 18 is located inside the welding head system housing 14, and includes a pressure block 24, an electrode 22 and an electrode air pump 23; the pressure block 24 is a π-shaped structure, consisting of a horizontal block and two vertical blocks, and is a symmetrical structure. The welding area of ​​the workpiece 3 to be welded is pressurized from above through the pressure block 24; there are two electrode air pumps 23 and two electrodes 22, both of which are arranged on both sides of the pressure block 24; there are two pressure motors 17, which are respectively located on both sides of the welding area of ​​the workpiece 3 to be welded, and the pressure motor 17 pressurizes the welding area from both sides.

[0013] The components of the rib beam welding head system 13 are the same, the only difference is that the two point focusing microwave antennas 21 in the rib beam welding head system 13 are arranged downward. When the flat plate welding head system 12 is used, the pressure is applied by the pressure motor 17 in the flat plate welding head system 12, and the pressure block 24 is not pressurized at this time; when the rib beam welding head system 13 is used, the pressure is applied by the pressure block 24 in the rib beam welding head system 13, and the pressure motor 17 is not pressurized at this time.

[0014] The specific structure of the stiffener beam welding head system 13 is described as follows: the stiffener beam welding head system 13 includes a welding head system housing 14, a resistance welding system 18, a pressurizing motor 17 and a microwave heating system 19; the welding head system housing 14 is a box structure, wherein the lower part of the two opposite surfaces and the bottom surface are provided with openings that are consistent with the protruding shape of the welding position of the welded part 3 to avoid interference with the welded part 3, the welding head system housing 14 is placed above the welded part 3 by the robot system 4, the bottom of the welding head system housing 14 is in contact with the operating platform 2, and the openings of the two opposite surfaces of the welding head system housing 14 are in contact with the outer surface of the welded part 3 to be welded, so that a sealed space is formed inside the welding head system housing 14 to prevent microwaves from escaping; the microwave heating system 19 includes a microwave source 15, a power amplifier 16, two point-focusing microwave antennas 21 and a flexible waveguide 20; the microwave source 15 and the power amplifier 16 are installed on the upper surface of the welding head system housing 14; the upper surface of the welding head system housing 14 is provided with an opening for the flexible waveguide 20 to pass through; the power amplifier 16, one end of which is connected to the microwave source 15, and the other end of which is connected to two point-focusing microwave antennas 21. The two point-focusing microwave antennas 21 are fixed on the inner wall of the welding head system housing 14, and are arranged downward. The two point-focusing microwave antennas 21 enclose the welding position. The microwaves emitted by the microwave source 15 are guided to the two point-focusing microwave antennas 21 through the flexible waveguide 20 after passing through the power amplifier 16. Since there are microwave focusing lenses inside the point-focusing microwave antennas 21, the microwaves can be focused on the welding position, and the welding position is heated by the microwave heating system 19. The resistance welding system 18 is located inside the welding head system housing 14, and includes a pressure block 24, an electrode 22 and an electrode air pump 23; the pressure block 24 is a π-shaped structure, consisting of a horizontal block and two vertical blocks, and is a symmetrical structure. The welding area of ​​the workpiece 3 to be welded is pressurized from above through the pressure block 24; there are two electrode air pumps 23 and two electrodes 22, both of which are arranged on both sides of the pressure block 24; there are two pressure motors 17, which are respectively located on both sides of the welding area of ​​the workpiece 3 to be welded, and the pressure motor 17 pressurizes the welding area from both sides.

[0015] The robot system 4 includes a base 8, a robot 6, a stepper motor 5 and a lead screw guide 7. The lead screw guide 7 is mounted on the base 8. The bottom of the robot 6 is mounted on the lead screw guide 7. The lead screw guide 7 is connected to the output end of the stepper motor 5. The lead screw guide 7 is driven by the stepper motor 5 to control the robot 6 to move left and right. The robot system 4 is used to move the flat plate welding head system 12 or the stiffener beam welding head system 13 to the welding position.

[0016] The material of the parts to be welded 3 is carbon-based material, magnetic material such as ferrite, microwave absorbing material such as SiC.

[0017] The welding objects used in the utility model include welding of T-beams, L-beams, I-beams, I-shaped beams and the like with flat plates, as well as welding of various overlapping forms such as flat plate warping and flat plate bending.

[0018] The beneficial effects of the utility model are:

[0019] The utility model uses the method of heating thermoplastic materials to a molten state in a microwave environment to soften the parts to be welded, thereby making the welding area fit tightly and correcting the warping problem of the parts to be welded, effectively ensuring the welding quality. This is the function of microwave assisted heating, which is aimed at the problem of welding failure caused by too large or too small gap in the welding area due to springback deformation or insufficient processing accuracy of the parts to be welded.

[0020] In addition, combined with the application of microwave absorbing dielectric materials, microwave absorbing dielectric materials are set at the welding interface. During welding, the microwave absorbing dielectric materials heat up quickly, causing the material in the welding area to melt, and after solidification, a welding joint is formed, completing microwave welding.

[0021] This patent adopts a step-by-step pressurization design to replace the roller pressurization design used in the patent (CN212219341U), which ensures the uniformity of pressure during welding and thus ensures the welding quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is an overall schematic diagram of the utility model;

[0023] Figure 2 It is a schematic diagram of the robot system of the utility model;

[0024] Figure 3 It is a schematic diagram of the operating platform of the utility model;

[0025] FIG. 4( a ) is a schematic diagram of a workpiece to be welded according to the present invention, and FIG. 4( b ) is a partial enlarged diagram of the bending lap welding area of ​​the flat-plate workpiece 9 and the workpiece 11 to be welded in FIG. 4( a );

[0026] Figure 5 It is a schematic diagram of the welding head system of the utility model;

[0027] FIG6(a) is an overall schematic diagram of a flat plate welding head system of the present invention, FIG6(b) is an overall schematic diagram of a microwave heating system and a pressurizing system in the flat plate welding head system, FIG6(c) is a schematic diagram of a microwave heating system, FIG6(d) is a schematic diagram of a pressurizing system, and FIG6(e) is a schematic diagram of a resistance welding system;

[0028] FIG. 7( a ) is an overall schematic diagram of the reinforcing rib beam welding joint system of the present invention, FIG. 7( b ) is a microwave heating system in the reinforcing rib beam welding joint system, and FIG. 7( c ) is an overall schematic diagram of the pressurizing system in the reinforcing rib beam welding joint system;

[0029] Figure 8 It is a schematic diagram of the structure of the supporting wedge-shaped slider welded with the mouth beam, C-beam, etc. and the flat plate;

[0030] Figure 9(a) to Figure 9(c) It is a patented (CN212422216U) robot-assisted continuous resistance welding equipment for thermoplastic materials, wherein FIG9(a) is the general assembly drawing; FIG9(b) is the continuous pressurizing module; FIG9(c) is the step-by-step pressurizing module;

[0031] FIG. 10( a ) and FIG. 10( b ) are warped thermoplastic parts to be welded, wherein FIG. 10( a ) is a front view; FIG. 10( b ) is an axonometric view;

[0032] Figure 11(a) to Figure 11(d) The welded parts are interference fit and clearance fit, wherein FIG11(a) is an interference fit welded part, FIG11(b) is a partial enlarged view of the interference fit welded part, and a welding film heating element is provided in the weld; FIG11(c) is a clearance fit welded part, and FIG11(d) is a partial enlarged view of the clearance fit welded part, and a welding film heating element is provided in the weld;

[0033] Fig.12 It is a welding structure type of reinforcing ribs and flat plates suitable for the utility model.

[0034] Fig.13 The utility model is suitable for the welding structure type of flat plate overlap and flat plate bending overlap.

[0035] In the figure: 1 welding head system; 2 operating platform; 3 parts to be welded; 4 robot system; 5 stepper motor; 6 robot; 7 lead screw guide rail; 8 base; 9 flat plate part to be welded 1; 10 rib beam parts to be welded; 11 flat plate part to be welded 2; 12 flat plate welding head system; 13 rib beam welding head system; 14 welding head system housing; 15 microwave source; 16 power amplifier; 17 left and right pressurizing motors; 18 resistance welding system; 19 microwave heating system; 20 flexible waveguide; 21 point focusing microwave antenna; 22 electrode; 23 electrode air pump; 24 pressurizing block; 25 wedge-shaped slider; 26 mouth beam. DETAILED DESCRIPTION

[0036] The specific implementation of the utility model is further described below in combination with the technical scheme and the accompanying drawings.

[0037] like Figure 1As shown, a microwave-resistance combined fusion welding equipment with low welding pressure of the utility model comprises a robot system 4, a welding head system 1, an operating platform 2 and a workpiece 3 to be welded.

[0038] like Figure 2 As shown, the robot system 4 includes a base 8, a robot 6, a stepper motor 5 and a lead screw guide 7. The lead screw guide 7 is mounted on the base 8, the bottom of the robot 6 is mounted on the lead screw guide 7, and the lead screw guide 7 is connected to the output end of the stepper motor 5. The robot 6 is a source that can provide sufficient pressure and power. When the stepper motor 5 is started, the lead screw rotates 7 to drive the robot 6 to move forward and backward, thereby expanding the operating space of the robot 6.

[0039] like Figure 3 As shown, the operating platform 2 is placed on the ground, and the upper surface of the operating platform 2 is used to place the parts to be welded 3 and the required fixing tools; the table top of the operating platform 2 is made of insulating material, and the frame below is made of ordinary metal material.

[0040] Fig. 4 (a) and Fig. 4 (b) are schematic diagrams of two types of welded parts 3 applicable to the utility model, which are two typical welding structures. One is the welding of a flat plate welded part 1 9 and a flat plate welded part 2 11. The welding position is a typical assembly structure. The manufacturing precision of the welded parts is high, and the assembly is clearance fit. The other is the welding of a rib-type welded part and a flat plate-type welded part. The figure shows a typical welding of a "J"-shaped beam 10 (rib) and a flat plate welded part 1 9 (flat plate).

[0041] like Figure 5 As shown, the welding head system is used to perform microwave-assisted heating and resistance welding on the workpiece 3 to be welded, including a flat plate welding head system 12 and a stiffener beam welding head system 13, which are respectively adapted to the two welding structures of FIG. 4(a).

[0042] like Figure 6(a) to Figure 6(e) As shown, the flat plate welding head system 12 includes a resistance welding system 18, a welding head system housing 14, two left and right pressurizing motors 17 and a microwave heating system 19. The welding head system housing 14 is mainly used to prevent microwaves from escaping to the outside, the resistance welding system 18 is used to complete resistance welding of the parts to be welded, the microwave heating system 19 is used to heat the parts to be welded to a softening degree, to facilitate deformation of the parts to be welded during welding, and to ensure welding quality, and the pressurizing system 17 is used to pressurize the parts to be welded from both sides.

[0043] The resistance welding system 18 includes a pressure block 24 , an electrode air pump 23 , and positive and negative electrodes 22 .

[0044] The microwave heating system 19 includes a microwave source 15, a power amplifier 16, two point-focusing microwave antennas 21 and a flexible waveguide 20. The microwave source 15 and the power amplifier 16 are fixed on the upper surface of the housing 14 and connected to the power amplifier 16. The power amplifier 16 amplifies the microwave power and then connects to the flexible waveguide 20. The flexible waveguide 20 guides the microwave to the two point-focusing microwave antennas 21. The point-focusing microwave antennas 21 are fixed on the inner wall of the housing 14. The left and right two point-focusing microwave antennas 21 can enclose the welding position and focus the microwave on the welding position.

[0045] like Figure 7(a) to Figure 7(c) As shown, the rib welding head system 13 is similar to the flat plate welding head system 12, except that the welding area is oriented in the up-down direction, that is, the two point-focused microwave antennas 21 in the rib welding head system 13 are both oriented downward. The two point-focused microwave antennas 21 in the flat plate welding head system 12 are oriented oppositely.

[0046] The working process of this utility model:

[0047] 1. Working of flat plate welding head system 12:

[0048] 1. Place a heating element and a welding film at the welding seam position, connect the positive and negative electrodes 22, and set a wedge-shaped slider 25 (such as a Figure 8 As shown), it is used to support the left and right pressure or the up and down pressure of the flat plate welding head system 12 to prevent the reinforcement composite material from being damaged under the pressure.

[0049] 2. Start the robot system 4 and move the flat plate welding head system 12 to the welding position of the workpiece to be welded.

[0050] 3. Start the microwave source 15 to emit microwaves, amplify the microwave power through the power amplifier 16, and guide the microwaves to the point focusing lens antenna 21 through the flexible waveguide 20. The point focusing lens antenna 21 completely wraps the welding position of the workpiece 3 to be welded in the point focusing lens antenna 21, and the microwaves are focused on a small area on the workpiece 3 to be welded through the microwave lens 21.

[0051] 4. The workpiece 3 to be welded is heated by microwaves. After the workpiece 3 to be welded is softened, the left and right pressure motors 17 provide clamping pressure to make the shapes of the workpieces 3 to be welded adapt to each other and provide pressure for the next step of resistance welding.

[0052] 5. Start the DC power supply, and the current flows through the positive electrode-heating element-negative electrode, causing the heating element to heat up and melt the welding film and the resin matrix in the welding area.

[0053] 6. Pressure holding stage: After the temperature of the welding area drops below the curing temperature, the pressure of the left and right electric cylinders 17 is still maintained until the welding area is completely cured.

[0054] 2. Work of the reinforcement welding head system 13:

[0055] 1. Place the heating element and welding film at the welding position and connect the positive and negative electrodes 22.

[0056] 2. Start the robot system 4 and move the reinforcement welding head system 13 to the welding position of the workpiece to be welded.

[0057] 3. Start the microwave source 15 to emit microwaves, amplify the microwave power through the power amplifier 16, and guide the microwaves to the point focusing lens antenna 21 through the flexible waveguide 20. The point focusing lens antenna 21 completely wraps the welding position of the workpiece 3 to be welded in the point focusing lens antenna 21, and the microwaves are focused on a small area on the workpiece 3 to be welded through the microwave lens 21.

[0058] 4. The workpiece 3 to be welded is heated by microwaves. After the workpiece 3 to be welded is softened, the pressure block 24 provides clamping pressure to make the shapes of the workpieces 3 to be welded adapt to each other and provide pressure for the next step of resistance welding.

[0059] 5. Start the DC power supply, and the current flows through the heating element and the welding film. When the temperature of the heating element and the welding film at the welding position rises, the workpiece 3 to be welded and the welding film are melted, and the welding process requirements are met.

[0060] 6. Pressure holding stage: After the temperature of the welding area drops below the curing temperature, the pressure of the upper and lower electric cylinders 17 is still maintained until the welding area is completely cured.

[0061] Furthermore, according to the concept of the present invention, the device of the present invention can be made into a handheld microwave heating assisted resistance welding equipment.

[0062] Furthermore, the idea of ​​microwave heating assisted welding process can be extended to the fields of induction welding, laser welding, ultrasonic welding, etc., to help solve the defects of being unable to weld or having poor welding quality caused by warping deformation, assembly tolerance mismatch and other problems in the process of resistance welding, induction welding, laser welding and ultrasonic welding.

[0063] Furthermore, the microwave-assisted heating principle of the present invention can be applied to the improvement of processing equipment such as molding, injection molding, pultrusion, etc. of thermoplastic related materials.

[0064] Furthermore, the utility model is aimed at welding forms such as reinforcing rib-plate welding, plate lap joint, etc. In order to meet the requirements of pressure size and uniformity, some welding structure types involve welding support structures. The utility model is suitable for welding structure types such as Fig.12 and Fig.13 shown.

[0065] Furthermore, the utility model can also adopt a microwave heating process to weld the parts to be welded separately. In this case, a microwave dielectric material needs to be placed on the welding interface. The material needs to have a higher microwave absorption rate than the parts to be welded. When microwave working conditions are applied to the parts to be welded, the microwave dielectric material quickly heats up under the influence of microwaves, and the material in the welding area is melted and solidified to form a welding interface, thereby completing microwave welding.

Claims

1. A microwave-resistance combined melting welding device with low welding pressure, characterized in that: The low welding pressure microwave-resistance combined melting welding device comprises a welding head system (1), an operating platform (2) and a robot system (4); the welding head system (1) is installed on the execution end of the robot system (4), the robot system (4) is located on one side of the operating platform (2), and the workpiece (3) to be welded is placed on the operating platform (2); The welding head system (1) comprises a flat plate welding head system (12) and a rib beam welding head system (13), which are arranged in parallel; the parts to be welded (3) comprise flat plate parts to be welded and rib beam parts to be welded, the flat plate welding head system (12) is used for welding between a flat plate part to be welded (9) and a flat plate part to be welded (11), and the rib beam welding head system (13) is used for welding between a rib beam part to be welded (10) and a flat plate part to be welded (9); The flat plate welding head system (12) comprises a welding head system housing (14), a resistance welding system (18), a pressurizing motor (17) and a microwave heating system (19); the welding head system housing (14) is a box structure, wherein the lower parts of the two opposite surfaces and the bottom surface are provided with openings having the same shape as the protrusions at the welding position of the welded parts (3) to avoid interference with the welded parts (3); the welding head system housing (14) is placed above the welded parts (3) by a robot system (4); the bottom of the welding head system housing (14) contacts the operating platform (2); and the welding head system housing (14) is in contact with the operating platform (2). ) are in contact with the outer surface of the workpiece (3) to be welded, so that a sealed space is formed inside the welding head system housing (14) to prevent microwaves from escaping; the microwave heating system (19) comprises a microwave source (15), a power amplifier (16), two point-focusing microwave antennas (21) and a flexible waveguide (20); the microwave source (15) and the power amplifier (16) are mounted on the upper surface of the welding head system housing (14); an opening is provided on the upper surface of the welding head system housing (14) for the flexible waveguide (20) to pass through; one end of the power amplifier (16) is connected to the microwave source (15) is connected, and the other end is connected to two point-focusing microwave antennas (21). The two point-focusing microwave antennas (21) are fixed on the inner wall of the welding head system housing (14) and arranged relative to each other. The two point-focusing microwave antennas (21) enclose the welding position. The microwaves emitted by the microwave source (15) are guided to the two point-focusing microwave antennas (21) through the flexible waveguide (20) after passing through the power amplifier (16). Since there is a microwave focusing lens inside the point-focusing microwave antenna (21), the microwaves are focused on the welding position, and the welding position is heated by the microwave heating system (19). The resistance welding system (18) ) is located inside the welding head system housing (14), and includes a pressure block (24), an electrode (22) and an electrode air pump (23); the pressure block (24) is a π-shaped structure, consisting of a horizontal block and two vertical blocks, and is a symmetrical structure. The pressure block (24) is used to pressurize the welding area of ​​the workpiece (3) to be welded from above; there are two electrode air pumps (23) and two electrodes (22), both of which are arranged on both sides of the pressure block (24); there are two pressure motors (17), which are respectively located on both sides of the welding area of ​​the workpiece (3) to be welded, and the pressure motor (17) pressurizes the welding area from both sides; The components of the reinforcing rib beam welding head system (13) are the same, except that the two point focusing microwave antennas (21) in the reinforcing rib beam welding head system (13) are arranged downward; when the flat plate welding head system (12) is used, the pressure is applied by the pressure motor (17) in the flat plate welding head system (12), and the pressure block (24) does not apply pressure; when the reinforcing rib beam welding head system (13) is used, the pressure is applied by the pressure block (24) in the reinforcing rib beam welding head system (13), and the pressure motor (17) does not apply pressure; The robot system (4) comprises a base (8), a robot (6), a stepper motor (5) and a lead screw guide (7), wherein the lead screw guide (7) is mounted on the base (8), the bottom of the robot (6) is mounted on the lead screw guide (7), the lead screw guide (7) is connected to the output end of the stepper motor (5), and the lead screw guide (7) is driven by the stepper motor (5) to control the robot (6) to move left and right; the robot system (4) is used to move the flat plate welding head system (12) or the reinforcing rib beam welding head system (13) to a welding position.

2. A microwave-resistance combined melting welding device with low welding pressure according to claim 1, characterized in that: The material of the parts to be welded (3) is a carbon-based material, a magnetic material or a microwave absorbing material.

3. A microwave-resistance combined melting welding device with low welding pressure according to claim 1 or 2, characterized in that: Applicable welding objects include welding of T-beams, L-beams, I-beams, and I-shaped beams with flat plates, flat plate warping, and lap welding including flat plate bending.

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