U-rib welding device and welding method for bridge

Abstract

The present invention relates to a U-rib welding device and method for bridges, which belongs to the field of welding technology, and comprises: a workbench is arranged at a welding station, and the workbench is used to install the bridge deck steel plate; a positioning component is connected between the bridge deck steel plate and the end face of the U-rib plate, and is used to position and install the U-rib plate on the bridge deck steel plate; a welding rod is used to abut between the bridge deck steel plate and the end face of the U-rib plate, and the welding rod is U-shaped and is connected to a power supply; a winding component is connected to both ends of the welding rod, and the winding component is used to retract and release the welding rod; the device can solve the technical problem in the prior art that the weld of the U rib is subjected to secondary heating and produces adverse effects.

Description

Technical Field

[0001] The invention belongs to the technical field of welding, and in particular relates to a U-rib welding device and a welding method for bridges. Background Art

[0002] U-ribs (U-shaped stiffening ribs) are one of the core load-bearing components of bridge steel structures (especially steel box girder bridge decks). Their welding accuracy is directly related to the mechanical properties, fatigue life and overall safety of the structure. To obtain better mechanical properties, the existing welding method generally uses two welds on the inner and outer sides of the U-rib, with the outer side welded by a manipulator and the inner side welded by a tunnel robot. However, it is difficult to weld the inner and outer sides simultaneously. The heat generated by the secondary welding of the same side wall will cause metallographic changes and / or mechanical property changes in the weld on the other side. Therefore, finding a method that can complete the welding of the inner and outer sides of the U-rib in one go to reduce the adverse effects caused by the secondary heating is a technical problem that technicians in this field urgently need to solve.

[0003] The existing patent with publication number CN1080226A discloses a resistance diffusion welding process for copper and low-carbon steel. It uses a spot welder that is in direct contact with the weld. After power is applied and heating, the heat in the weld area is highly concentrated, causing the copper and low-carbon steel to undergo plastic deformation at the same time, and then diffuse. After 0.5-1 seconds, they are welded into one piece.

[0004] The existing technology has the following problems: although the spot welding machine can achieve simultaneous welding of the inner and outer sides of the U-rib side wall and obtain a more stable welding effect, it can only achieve point contact and surface contact. The weld of the U-rib will still experience secondary heating in the length direction, resulting in adverse effects. Summary of the Invention

[0005] The present invention provides a U-rib welding device and a welding method for bridges, which can solve the technical problem in the prior art that the weld of the U-rib is subjected to secondary heating and produces adverse effects.

[0006] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0007] The present application provides a U-rib welding device for a bridge, comprising:

[0008] A workbench, provided at the welding station, for installing the bridge deck steel plate;

[0009] A positioning assembly connected between the bridge deck steel plate and the end surface of the U-rib plate, and used for positioning and installing the U-rib plate on the bridge deck steel plate;

[0010] a welding rod, used for abutting between the bridge deck steel plate and the end surface of the U-rib plate, the welding rod being U-shaped and connected to a power source;

[0011] A winding assembly connected to both ends of the welding rod, the winding assembly being used to retract and release the welding rod;

[0012] The above-mentioned welding rod has a tungsten rod and two nickel-chromium alloy rods. The nickel-chromium alloy rod is connected to the winding assembly. The tungsten rod is connected between the two nickel-chromium alloy rods. After the nickel-chromium alloy rod is energized, the end faces of the bridge deck steel plate and the U-rib plate are preheated. After the tungsten rod is energized, the end faces of the bridge deck steel plate and the U-rib plate are heated and melted for welding. When the winding assembly retracts the welding rod, the tungsten rod is connected, heated, melted and welded along the length direction of the U-rib plate.

[0013] Through the above technical solution, welding rods are used to abut the end faces of the bridge deck steel plate and the U-rib plate for heating and melting welding, so that the contact surfaces of the two are fully melted and welded, avoiding the adverse effects of secondary heating of the weld and improving the metallographic stability and mechanical property stability after welding.

[0014] In the present invention, the positioning assembly includes:

[0015] A clamping frame, clamped to the side surface of the bridge deck steel plate in the longitudinal direction;

[0016] a cylinder connected to the clamping frame;

[0017] a locking ring, connecting the U-rib to the movable end of the cylinder;

[0018] The gap or extrusion pressure between the U-rib plate and the bridge deck steel plate is adjusted by lifting and lowering the cylinder.

[0019] Through the above technical solution, the cylinder is used to lift the U-rib plate to adjust the gap or extrusion pressure between the U-rib plate and the bridge deck steel plate, thereby preventing the welding rod from being unable to slide or break due to the dead weight of the U-rib plate, thereby optimizing the passing performance of the welding rod.

[0020] In the present invention, the winding assembly comprises:

[0021] a bracket connected to the workbench;

[0022] A winding roller is rotatably connected to the bracket, the winding roller is connected to the nickel-chromium alloy strip, and when the winding roller rotates, it pulls the nickel-chromium alloy strip to be retracted;

[0023] A driving motor is connected to the winding roller.

[0024] Through the above technical solution, the winding roller is used to complete the traction of the welding rod within a limited space, thereby optimizing the space size of the welding device.

[0025] In the present invention, the winding assembly further comprises:

[0026] The fan blades are rotatably connected to the bracket, and the fan blades are transmission-connected to the drive motor;

[0027] A plurality of heat dissipation fins are arranged in a ring on the inner side of the winding roller, and the heat dissipation fins are used to conduct heat away from the nickel-chromium alloy strip wound on the outer side of the winding roller.

[0028] Through the above technical solution, a drive motor is used to drive the fan blades and the winding roller at the same time, which saves the setting of the power source and improves the heat dissipation performance of the winding roller.

[0029] In the present invention, the welding device further comprises:

[0030] A pad is abutted between the bridge deck steel plate and the workbench, the pad is arranged parallel to the length direction of the U-rib plate, and the pad is arranged below the central axis of the bridge deck steel plate or below both sides of the central axis of the bridge deck steel plate;

[0031] A plurality of pressing plates are connected to the workbench. The pressing plates are arranged at equal intervals along the length direction of the bridge deck steel plate. The pressing plates and the pads cause the bridge deck steel plate to bend inversely to eliminate welding stress.

[0032] Through the above technical solution, pads and pressure plates are used to achieve the reverse curvature of the bridge deck steel plate to cope with the stress of material shrinkage after welding, thereby improving the geometric dimensional accuracy after welding.

[0033] In the present invention, the welding device further comprises:

[0034] a nano-ceramic layer coated on the outer side of the nickel-chromium alloy strip;

[0035] A lubricating layer is coated on the outer side of the nano-ceramic layer.

[0036] Through the above technical solution, the nano-ceramic layer plays an insulating role on the one hand, and improves the structural rigidity of the welding rod on the other hand, while the lubricating layer further enhances the insulation effect and the passing performance of the welding rod.

[0037] The present application also provides a method for welding U-ribs for bridges, which uses the above-mentioned U-rib welding device for bridges and further includes the following steps:

[0038] Step S10: installing the bridge deck steel plate on the workbench, placing the U-rib plate on top of the bridge deck steel plate, and using the positioning assembly to position and lift the U-rib plate;

[0039] Step S20: inserting the welding strip between the end surface of the U-rib and the bridge deck steel plate, and then adjusting the positioning assembly so that the welding strip can slide between the end surface of the U-rib and the bridge deck steel plate;

[0040] Step S30: The welding rod is powered on to heat the end surface of the U-rib and the bridge deck steel plate. After the two sides of the corresponding position of the tungsten rod begin to melt to form a molten pool, the driving motor is started to reel the welding rod. The molten pool moves along the length direction of the U-rib as the tungsten rod moves.

[0041] Through the above technical solution, welding rods are used to melt the contact position between the bridge deck steel plate and the end face of the U-rib plate, thereby obtaining sufficient welding depth. This also avoids the adverse effects caused by the heat generated by secondary welding when the inner and outer sides of the U-rib plate are welded separately, thereby improving the welding effect.

[0042] In the present invention, the above steps S10 and S20 further include:

[0043] Step S15: lift the bridge deck steel plate and place the pad underneath it, and use the pressure plates on both sides of the bridge deck steel plate to make the bridge deck steel plate bend inversely.

[0044] Through the above technical solution, pads and pressure plates are used to achieve the reverse curvature of the bridge deck steel plate to cope with the stress of material shrinkage after welding, thereby improving the geometric dimensional accuracy after welding.

[0045] In summary, this application has the following effects:

[0046] 1. Welding rods are used to contact the end faces of the bridge deck steel plate and the U-rib plate for heating and melting welding, so that the contact surfaces of the two are fully melted and welded, avoiding the adverse effects of secondary heating of the weld and improving the metallographic stability and mechanical property stability after welding;

[0047] 2. Use a cylinder to lift the U-rib to adjust the gap or extrusion pressure between the U-rib and the bridge deck steel plate, so as to prevent the welding rod from being unable to slide or break due to the dead weight of the U-rib, thereby optimizing the passing performance of the welding rod;

[0048] 3. The winding roller can complete the traction of the welding rod in a limited space, optimizing the space size of the welding device;

[0049] 4. The drive motor is used to drive the fan blades and the winding roller at the same time, which saves the setting of the power source and improves the heat dissipation performance of the winding roller;

[0050] 5. Pads and pressure plates are used to achieve the reverse curvature of the bridge deck steel plate to cope with the stress of material shrinkage after welding, thereby improving the geometric dimensional accuracy after welding;

[0051] 6. The nano-ceramic layer has an insulating effect on the one hand, and improves the structural rigidity of the welding rod on the other hand, while the lubricating layer further strengthens the insulating effect and the passing performance of the welding rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0053] Figure 1 An axonometric view of a U-rib welding device for bridges provided by an embodiment of the present invention after clamping a bridge deck steel plate and a U-rib;

[0054] Figure 2 A side view of a U-rib welding device for bridges provided by an embodiment of the present invention after clamping a bridge deck steel plate and a U-rib;

[0055] Figure 3 for Figure 2 The sectional view at AA in the figure;

[0056] Figure 4 A front view of a U-rib welding device for bridges provided by an embodiment of the present invention after clamping a bridge deck steel plate and a U-rib;

[0057] Figure 5 for Figure 4 Cross-sectional view at BB in the figure;

[0058] Figure 6 for Figure 5 A local enlarged view of point C in FIG;

[0059] Figure 7 for Figure 4 Cross-sectional view at DD in the figure;

[0060] Figure 8 for Figure 7 A local enlarged view of point E in FIG;

[0061] Figure 9 A schematic diagram of a partial structure of a welding rod provided in an embodiment of the present invention;

[0062] Figure 10 A cross-sectional view of a welding rod provided in an embodiment of the present invention;

[0063] Figure 11 for Figure 10 Cross-sectional view at FF in the figure.

[0064] Icons: 1-workbench; 2-positioning assembly; 201-clamping frame; 202-cylinder; 203-locking ring; 3-welding rod; 301-tungsten rod; 3011-heating zone; 3012-gradient zone; 302-nickel-chromium alloy rod; 303-insulating layer; 304-nanoceramic layer; 305-lubricating layer; 306-transition zone; 4-winding assembly; 401-winding roller; 402-fan blades; 403-heating fins; 404-drive motor; 405-bracket; 501-pad; 502-pressure plate; 6-bridge deck steel plate; 7-U rib. DETAILED DESCRIPTION

[0065] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0066] In the description of this application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0067] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. Throughout this application, unless otherwise specified, "plurality" means two or more.

[0068] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installation," "connection," and "connection" should be understood in a broad sense. For example, they can refer to welding, bolting, or riveting; fixed connection, detachable connection, or integral connection; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0069] Example:

[0070] Please refer to Figures 1 to 11 , Figures 1 to 11 An embodiment of the present application is shown.

[0071] This embodiment provides a U-rib welding device for bridges, such as Figures 1 to 3 As shown, it includes:

[0072] The workbench 1 is provided at the welding station. For example, a fixed workbench of a gantry machining center can be referred to. The workbench 1 is used to install the bridge deck steel plate 6. When placing the bridge deck steel plate 6, a crane is used to suck the bridge deck steel plate 6 with a magnetic suction cup and place it parallel to the T-slot of the workbench 1 to ensure the correct placement angle.

[0073] like Figure 3 As shown, the positioning assembly 2 is connected between the end surface of the bridge deck steel plate 6 and the U-rib plate 7, and is used to position and install the U-rib plate 7 on the bridge deck steel plate 6;

[0074] like Figure 6 As shown, the welding strip 3 is used to abut between the end faces of the bridge deck steel plate 6 and the U rib plate 7, as shown in FIG. Figure 11 As shown, the welding rod 3 is U-shaped and has an insulating layer 303 provided in the middle. Zirconia fiber cloth is exemplarily used, which can operate for a long time at 1500-2200 degrees Celsius and still maintain a complete fiber form at 2500 degrees Celsius to prevent arc breakdown. The welding rod 3 is connected to a power supply, which is a commercially available external finished product. It should be noted that any power supply with an adjustable function that can be used for heating resistance wire can be used, so no further description or specific limitation is given.

[0075] like Figure 3 As shown, the winding assembly 4 is connected to both ends of the welding rod 3. It should be noted that, as shown in FIG. Figure 11 The ends of the welding rod 3 shown are both nickel-chromium alloy rods 302, wherein the tungsten rod 301 is located in the middle section of the welding rod 3, and the winding assembly 4 is used to retract and release the welding rod 3;

[0076] The above-mentioned welding rod 3 has a tungsten rod 301 and two nickel-chromium alloy rods 302. The nickel-chromium alloy rod 302 is connected to the winding component 4. The tungsten rod 301 is connected between the two nickel-chromium alloy rods 302. The tungsten rod 301 has a heating zone 3011 and a gradient zone 3012 with gradually increasing width. At the same time, there is a transition zone 306 between the tungsten rod 301 and the nickel-chromium alloy rod 302. The transition zone 306 is formed by adopting an interpenetration welding process to avoid the influence of additional solder on the welding performance under high temperature. After the nickel-chromium alloy rod 302 is energized, the end faces of the bridge deck steel plate 6 and the U-rib plate 7 are preheated. After the tungsten rod 301 is energized, the end faces of the bridge deck steel plate 6 and the U-rib plate 7 are heated and melted for welding. When the winding component 4 retracts the welding rod 3, the tungsten rod 301 is connected along the length direction of the U-rib plate 7 for heating and melting welding.

[0077] It should be noted that the U-ribs 7 and the bridge deck steel plates 6 are generally made of low-carbon, high-strength steel such as Q345, which generally has a melting point between 1450°C and 1500°C. The softening temperature of tungsten is 1600°C, the melting point of nickel-chromium alloy is around 1400°C (but nickel-chromium alloy is only used for preheating), the melting point of nano-alumina ceramics is around 2050°C, and the melting point of boron nitride is around 3000°C. The operating temperature of the insulating layer 303 is also between 1500°C and 2200°C. Therefore, when the heating zone 3011 of the tungsten bar 301 is maintained in the operating temperature range of 1500°C to 1600°C, it can ensure both the heating and melting of the steel and the stability of the welding bar 3 itself. Figure 11 As shown, because the tungsten bar 301 also has a gradient zone 3012, its width gradually increases and its resistance decreases. Therefore, the temperature gradually transitions from 1500 degrees Celsius to below 1400 degrees Celsius to ensure that the nickel-chromium alloy bar 302 does not melt. The heating zone 3011 of the tungsten bar 301 is narrower than the gradient zone 3012. Therefore, the resistance of the heating zone 3011 is greater than that of the gradient zone 3012, and thus the heating zone 3011 generates more heat. Although the tungsten bar 301 and the nickel-chromium alloy bar 302 have their own thermal conductivity, the Q345 also absorbs the heat generated by the heating zone 3011 and dissipates it. When heat generation and heat dissipation are balanced, the temperature at the location with higher resistance will still be significantly higher than that at other areas, thereby forming a temperature gradient. The existence of the temperature gradient can meet the requirement that the metal at different locations is within a stable operating temperature range. However, the specific parameters of the different ranges need to be determined by those skilled in the art through theoretical calculations and limited experiments based on actual work objects. The specific parameters of the welding bar 3 are not within the scope of protection of this application and are therefore not described in detail or specifically limited.

[0078] Through the above technical solution, the welding rod 3 is used to abut the end faces of the bridge deck steel plate 6 and the U-rib plate 7 for heating and melting welding, so that the contact surfaces of the two are fully melted and welded, avoiding the adverse effects of secondary heating of the weld and improving the metallographic stability and mechanical property stability after welding.

[0079] As a preferred embodiment, the positioning assembly 2 includes:

[0080] The clamping frame 201 is clamped to the side surface of the bridge deck steel plate 6 in the longitudinal direction;

[0081] Cylinder 202, connected to the clamping frame 201;

[0082] The locking ring 203 connects the U-rib 7 to the movable end of the cylinder 202;

[0083] The gap or extrusion force between the U-rib 7 and the bridge deck steel plate 6 is adjusted by raising and lowering the cylinder 202 .

[0084] It should be noted that the specific control and linkage of the cylinder 202 belong to the existing technology and are not within the scope of protection of this application. Those skilled in the art can make choices based on public technical solutions or technical manuals, textbooks, etc., and no specific explanation or further limitation will be given here.

[0085] Through the above technical solution, the cylinder 202 is used to lift and lower the U-rib 7 to adjust the gap or extrusion pressure between the U-rib 7 and the bridge deck steel plate 6, thereby preventing the welding rod 3 from being unable to slide or break due to the dead weight of the U-rib 7, thereby optimizing the passing performance of the welding rod 3.

[0086] As a better implementation method, Figure 3 As shown, the winding assembly 4 includes:

[0087] Bracket 405, connected to workbench 1;

[0088] The winding roller 401 is rotatably connected to the bracket 405. The winding roller 401 is connected to the nickel-chromium alloy strip 302. When the winding roller 401 rotates, it pulls the nickel-chromium alloy strip 302 to be retracted.

[0089] The driving motor 404 is in driving connection with the winding roller 401 .

[0090] The driving motor 404 uses a small gear to directly drive the annular rack inside the winding roller 401, so that the winding roller 401 rotates slowly. The radius of the winding roller 401 needs to be selected in combination with the maximum bending radius of the welding rod 3. It should be noted that the maximum bending radius needs to be determined by theoretical calculation and a limited number of trial production tests based on parameters such as the thickness and yield strength of the nano-ceramic layer 304, and the maximum bending radius of the welding rod 3 needs to be selected in combination with the specific dimensions of various substrates inside it and the thickness of the layer. Those skilled in the art can select appropriate dimensional parameters through limited tests. The specific dimensional parameters do not fall within the scope of protection of this application and are therefore not further explained or specifically limited. For example, When the thickness of the tungsten bar 301 (metal sheet) is 0.8 mm, the width of the welding bar 3 is D, and the length of the heating zone 3011 of the tungsten bar 301 is L, and L ≥ 2D, the tungsten bar 301 is coated with a 20 μm thick insulating nano-ceramic layer 304 to wrap the tungsten bar 301. Both sides in the thickness direction directly contact the Q345 material. The Q345 material is not charged. The smallest section of the tungsten bar 301 needs to be heated to 1600 degrees Celsius while the potential cannot break through the insulating nano-ceramic coating. However, theoretically, the minimum width D does not exist at this time. Therefore, it is necessary to add a lubricating layer 305 on the outside of the insulating nano-ceramic layer 304. Boron nitride is used as an example to obtain a sufficient dielectric constant.

[0091] Through the above technical solution, the winding roller 401 is used to complete the pulling of the welding rod 3 in a limited space, thereby optimizing the space size of the welding device.

[0092] As a preferred embodiment, the winding assembly 4 further includes:

[0093] The fan blade 402 is rotatably connected to the bracket 405, and the fan blade 402 is transmission-connected to the drive motor 404;

[0094] A plurality of heat dissipation fins 403 are arranged around the inner side of the winding roller 401 . The heat dissipation fins 403 are used to dissipate heat from the nickel-chromium alloy strip 302 wound around the outer side of the winding roller 401 .

[0095] Through the above technical solution, the drive motor 404 is used to drive the fan blades 402 and the winding roller 401 at the same time, which saves the setting of the power source and improves the heat dissipation performance of the winding roller 401.

[0096] As a preferred embodiment, the welding device further includes:

[0097] The pad 501 is abutted between the bridge deck steel plate 6 and the workbench 1. The pad 501 is arranged parallel to the length direction of the U-rib 7. The pad 501 is arranged below the central axis of the bridge deck steel plate 6 or below both sides of the central axis of the bridge deck steel plate 6.

[0098] A plurality of pressing plates 502 are connected to the workbench 1 . The pressing plates 502 are arranged at equal intervals along the length direction of the bridge deck steel plate 6 . The pressing plates 502 and the pads 501 cause the bridge deck steel plate 6 to bend inversely to eliminate welding stress.

[0099] Through the above technical solution, the pad 501 and the pressure plate 502 are used to achieve the reverse curvature of the bridge deck steel plate 6 to cope with the stress of material shrinkage after welding, thereby improving the geometric dimensional accuracy after welding.

[0100] As a preferred embodiment, the welding device further includes:

[0101] The nano-ceramic layer 304, exemplarily made of nano-alumina ceramic, is coated on the outer side of the nickel-chromium alloy strip 302;

[0102] The lubricating layer 305 , exemplarily a boron nitride coating, is coated on the outer side of the nano-ceramic layer 304 .

[0103] Through the above technical solution, the nano-ceramic layer 304 has an insulating effect on the one hand, and improves the structural rigidity of the welding rod 3 on the other hand, while the lubricating layer 305 further enhances the insulating effect and the passing performance of the welding rod 3.

[0104] To use, follow these steps:

[0105] Step S10: Install the bridge deck steel plate 6 on the workbench 1, place the U-rib plate 7 on the bridge deck steel plate 6, and use the positioning assembly 2 to position and lift the U-rib plate 7;

[0106] Step S20: inserting the welding strip 3 between the end surface of the U-rib 7 and the bridge deck steel plate 6, and then adjusting the positioning assembly 2 so that the welding strip 3 can slide between the end surface of the U-rib 7 and the bridge deck steel plate 6;

[0107] Step S30: The welding rod 3 is powered on to heat the end surface of the U-rib 7 and the bridge deck steel plate 6. After the tungsten rod 301 begins to melt on both sides of the corresponding position to form a molten pool, the drive motor 404 is started to reel the welding rod 3. The molten pool moves along the length direction of the U-rib 7 as the tungsten rod 301 moves.

[0108] As a preferred embodiment, the above steps S10 and S20 further include:

[0109] Step S15: lift the bridge deck steel plate 6 and place a pad 501 underneath it, and use the pressure plates 502 on both sides of the bridge deck steel plate 6 to make the bridge deck steel plate 6 bend backward.

[0110] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope of the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A U-rib welding device for bridges, characterized in that: include: A workbench (1) is provided at the welding station, wherein the workbench (1) is used to install the bridge deck steel plate (6); A positioning assembly (2) is connected between the end faces of the bridge deck steel plate (6) and the U-rib plate (7) and is used to position and install the U-rib plate (7) on the bridge deck steel plate (6); A welding bar (3) is used for contacting between the end faces of the bridge deck steel plate (6) and the U-rib plate (7), wherein the welding bar (3) is U-shaped and is connected to a power source; A winding assembly (4) connected to both ends of the welding rod (3), the winding assembly (4) being used to retract and release the welding rod (3); The welding rod (3) comprises a tungsten rod (301) and two nickel-chromium alloy rods (302), the nickel-chromium alloy rod (302) being connected to the winding assembly (4), the tungsten rod (301) being connected between the two nickel-chromium alloy rods (302), the nickel-chromium alloy rod (302) being energized to preheat the end faces of the bridge deck steel plate (6) and the U-rib plate (7), the tungsten rod (301) being energized to heat and melt the end faces of the bridge deck steel plate (6) and the U-rib plate (7), and when the winding assembly (4) retracts the welding rod (3), the tungsten rod (301) is connected along the length direction of the U-rib plate (7) for heating and melting welding. The welding rod (3) is U-shaped and has an insulating layer (303) provided in the middle. The tungsten bar (301) has a heating zone (3011) and a gradual change zone (3012) with gradually increasing width, so as to ensure that the nickel-chromium alloy bar (302) does not melt; A transition zone (306) is also provided between the tungsten strip (301) and the nickel-chromium alloy strip (302).

2. The U-rib welding device for bridge according to claim 1, characterized in that: The positioning component (2) comprises: A clamping frame (201) is clamped to the side surface of the bridge deck steel plate (6) in the longitudinal direction; A cylinder (202) connected to the clamping frame (201); A locking ring (203) connects the U-rib (7) to the movable end of the cylinder (202); The gap or extrusion force between the U-rib plate (7) and the bridge deck steel plate (6) is adjusted by raising and lowering the cylinder (202).

3. The U-rib welding device for bridge according to claim 2, characterized in that: The winding assembly (4) comprises: A bracket (405) connected to the workbench (1); A winding roller (401) is rotatably connected to the bracket (405), the winding roller (401) is connected to the nickel-chromium alloy strip (302), and the winding roller (401) pulls the nickel-chromium alloy strip (302) to be retracted when rotating; A driving motor (404) is connected in transmission connection with the winding roller (401).

4. The U-rib welding device for bridge according to claim 3, characterized in that: The winding assembly (4) further comprises: The fan blade (402) is rotatably connected to the bracket (405), and the fan blade (402) is transmission-connected to the drive motor (404); A plurality of heat dissipation fins (403) are arranged in a ring on the inner side of the winding roller (401), and the heat dissipation fins (403) are used to dissipate heat from the nickel-chromium alloy strip (302) wound on the outer side of the winding roller (401).

5. The U-rib welding device for bridge according to claim 4, characterized in that: Also includes: A pad (501) is abutted between the bridge deck steel plate (6) and the workbench (1), the pad (501) is arranged parallel to the length direction of the U-rib plate (7), and the pad (501) is arranged below the central axis of the bridge deck steel plate (6) or below both sides of the central axis of the bridge deck steel plate (6); A plurality of pressing plates (502) are connected to the workbench (1), wherein the pressing plates (502) are arranged at equal intervals along the length direction of the bridge deck steel plate (6), and the pressing plates (502) and the pads (501) cause the bridge deck steel plate (6) to bend inversely to eliminate welding stress.

6. The U-rib welding device for bridges according to claim 5, characterized in that: Also includes: a nano-ceramic layer (304) coated on the outer side of the nickel-chromium alloy strip (302); A lubricating layer (305) is coated on the outside of the nano-ceramic layer (304).

7. A method for welding U-ribs for bridges, characterized in that: The U-rib welding device for bridges according to claim 6 is used, further comprising the following steps: Step S10: installing the bridge deck steel plate (6) on the workbench (1), placing the U-rib plate (7) above the bridge deck steel plate (6), and using the positioning assembly (2) to position and lift the U-rib plate (7); Step S20: inserting the welding strip (3) between the end surface of the U-rib plate (7) and the bridge deck steel plate (6), and then adjusting the positioning assembly (2) so that the welding strip (3) can slide between the end surface of the U-rib plate (7) and the bridge deck steel plate (6); Step S30: The welding rod (3) is powered on to heat the end surface of the U-rib (7) and the bridge deck steel plate (6). After the two sides of the corresponding position of the tungsten rod (301) begin to melt to form a molten pool, the driving motor (404) is started to reel the welding rod (3). The molten pool moves along the length direction of the U-rib (7) as the tungsten rod (301) moves.

8. The U-rib welding method for bridges according to claim 7, characterized in that: The steps between step S10 and step S20 also include: Step S15: lift the bridge deck steel plate (6) and place the pad (501) thereunder, and use the pressing plates (502) on both sides of the bridge deck steel plate (6) to cause the bridge deck steel plate (6) to bend inversely.

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