Welding equipment for plate welding and composite welding method thereof

Abstract

A composite welding device for plate tailor welding and a welding method thereof, comprising a mounting frame, a plasma arc welding gun, a submerged arc welding gun, a laser tracking probe and a recovery pipe, the plasma arc welding gun is used for plasma arc welding of the plate, the submerged arc welding gun is used for submerged arc welding of the plate, the laser tracking probe is used for acquiring the weld information between the plates, and the recovery pipe is used for recovering the flux required for submerged arc welding; the laser tracking probe, the plasma arc welding gun, the submerged arc welding gun and the recovery pipe are sequentially arranged on the mounting frame, and the laser tracking probe, the plasma arc welding gun, the submerged arc welding gun and the recovery pipe are located on the same straight line, so that the plasma arc welding gun and the submerged arc welding gun can simultaneously weld the plates while acquiring the weld information, thereby improving the welding precision and the welding efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of welding, and in particular relates to welding equipment for plate tailor welding and a composite welding method thereof. Background Art

[0002] In the fields of shipbuilding, petrochemical equipment, etc., plate welding is often involved. These plates are often thick. For medium and thick plates, argon arc welding or manual arc welding is often used for base welding, and then the back is cleaned and the bottom is welded. Then, submerged arc welding is used for filling welding and cover welding on the front. During the welding process, in order to reduce welding deformation, the front and back sides of the plate need to be welded alternately. This welding method has the following shortcomings: (1) Since the two sides of the plate need to be alternately welded, it is difficult to turn the plate over. It needs to be turned over with the help of a turning device, and it also places very high requirements on the height of the welding production workshop; (2) It is impossible to achieve double-sided welding at the same time, and the welding process involves switching between two or more welding methods and equipment, resulting in low welding efficiency; (3) For the welding of thick plates, a larger groove is required, which requires more filling materials, increasing the welding production cost while reducing the welding production rate.

[0003] The invention patent with application number 202210651291.5 discloses a welding gun conversion tooling for a welding robot, including a robot body, the end of the robot body is rotatably connected to a welding arm, a stepper motor for driving the welding arm to rotate is fixedly installed on the side of the robot body, a group of welding gun modules distributed in a linear array are fixedly installed on the inner wall of the welding arm, a screw drive module is fixedly installed on the inner wall of the welding arm, a gun pusher plate is slidably connected to the inner wall of the welding arm, the inner wall of the gun pusher plate is transmission-connected to the screw drive module, a magnetic control seat is fixedly installed on the surface of the gun pusher plate and corresponding to the position of each welding gun module, and the inner wall of the magnetic control seat is slidably connected to a piston column that cooperates with the welding gun module. The above-mentioned welding gun conversion tooling has the following main deficiencies: (1) each welding gun works independently, resulting in the need for multiple welding for the same weld; (2) since the spacing and angles between the welding guns cannot be adjusted, the positional relationship between the welding heads of multiple welding guns cannot be adjusted, resulting in only a single welding eutectic pool being achieved during the welding process, and the eutectic pool formed by welding cannot be fully coupled, partially coupled, or completely separated, making the function of the welding device relatively single. Summary of the Invention

[0004] In view of the above shortcomings, the technical problem to be solved by the present invention is to provide a welding device for plate welding and a composite welding method thereof, so as to improve the welding difficulty and welding efficiency of the plate.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A composite welding device for plate welding comprises a mounting frame, a plasma arc welding gun for performing plasma arc welding on the plate, and at least one submerged arc welding gun for performing submerged arc welding on the plate. The plasma arc welding gun and the submerged arc welding gun are mounted on the mounting frame via a connecting assembly. The connecting assembly can slide and rotate relative to the mounting frame. The plasma arc welding gun and the submerged arc welding gun are located on the same straight line.

[0007] As a preferred solution of the present invention, the connecting assembly includes a sliding connector slidably connected to the mounting frame and a rotating connector for mounting a plasma arc welding gun or a submerged arc welding gun. The rotating connector can be rotatably mounted on the sliding connector to adjust the inclination angle of the plasma arc welding gun or the submerged arc welding gun through the rotating connector.

[0008] As a preferred solution of the present invention, the sliding connection includes a slider slidably connected to the mounting frame and a sleeve for connecting to the rotating connection member. The sleeve portion is connected to the slider, and an open groove for the sleeve diameter is provided on the sleeve. A locking member adapted to the mounting frame is installed on the slider to lock the slider on the mounting frame.

[0009] As a preferred solution of the present invention, the rotating connecting member includes a clamp for rotatably mounting a plasma arc welding gun or a submerged arc welding gun and a welding gun sleeve for mounting a plasma arc welding gun or a submerged arc welding gun. The clamp is rotatably connected to the sliding connecting member, and the welding gun sleeve is inserted into the clamp.

[0010] As a preferred solution of the present invention, two connecting assemblies are installed at different heights of the submerged arc welding gun, and the submerged arc welding gun is adjustably mounted on the mounting frame through the two connecting assemblies.

[0011] As a preferred solution of the present invention, a laser tracking probe for obtaining weld information is also installed on the mounting frame, and the laser tracking probe is arranged at the front end of the plasma arc welding gun.

[0012] As a preferred solution of the present invention, a recovery pipe for recovering flux is also installed on the mounting frame, and the recovery pipe is arranged behind the submerged arc welding gun.

[0013] The above-mentioned welding method of the composite welding device for plate welding comprises the following steps:

[0014] S1, fixing the laser tracking probe, plasma arc welding gun, and submerged arc welding gun on the welding device in sequence, and adjusting the spacing and angle relationship between the plasma arc welding gun and the submerged arc welding gun according to the thickness of the welding plate;

[0015] S2, starting the welding device, aligning the laser tracking probe, plasma arc welding gun, and submerged arc welding gun with the weld simultaneously, obtaining weld seam information through the laser tracking probe, and calculating the movement path of the welding device and the number of operations of the submerged arc welding gun based on the weld seam information;

[0016] S3, the plasma arc welding gun and the submerged arc welding gun work simultaneously, the plasma arc welding gun is located at the front end of the submerged arc welding gun, the plasma arc welding gun is used to perform single-sided welding and double-sided forming welding on the plate, and then the submerged arc welding gun is used to perform submerged arc welding on the weld.

[0017] As a preferred solution of the present invention, in step S2, the number of operations of the submerged arc welding gun is positively correlated with the thickness of the plate.

[0018] As a preferred solution of the present invention, the plate is provided with a groove for submerged arc welding at the weld of the plate according to the thickness of the plate.

[0019] Compared with the prior art, the present invention has the following advantages: (1) a single welding device can be used to perform both plasma arc welding and submerged arc welding on the plate at one time, thereby increasing the welding penetration, welding speed and welding cladding rate.

[0020] (2) Compared with the existing alternating front and back welding, the present application avoids the back root cleaning, bottom welding and plate turning processes in the flat plate welding process by arranging multiple welding operations on the same side of the plate to be welded, thereby greatly improving the welding production efficiency and reducing the requirements for the welding workshop.

[0021] (3) Compared with the existing welding devices, the spacing and tilt angles between the welding guns in this welding device can be adjusted, which is convenient for adjusting the position relationship between the welding heads of multiple welding guns. By adjusting the positions of the welding heads of multiple welding guns, the eutectic pool formed by welding can be fully coupled, partially coupled and completely separated, thereby adapting to different welding requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural diagram of the composite welding device.

[0023] Figure 2 It is a structural schematic diagram of the hybrid welding device with the plasma arc welding gun and submerged arc welding gun hidden.

[0024] Figure 3 yes Figure 2 Schematic diagram of the structure after rotating at a certain angle.

[0025] Figure 4 It is a structural diagram of the connecting bracket.

[0026] Figure 5 It is a structural diagram of the connection block.

[0027] Figure 6 It is a structural diagram of the connected components.

[0028] Figure 7 It is a structural diagram of the clamp.

[0029] Figure markings: mounting frame 1, mounting rod 1-1, connecting bracket 1-2, slide rail 1-3, side rod 1-4, connecting block 1-5, connecting column 1-6, holding hole 1-7, limit screw 1-8, adapter block 1-9, spinning block 1-10, probe mounting column 1-11, probe clamping block 1-12, plasma arc welding gun 2, submerged arc welding gun 3, welding gun body 3-1, hopper 3-2, connecting assembly 4, sliding connector 4-1, rotating connector 4-2, slider 4-3, sleeve 4-4, opening groove 4-5, locking member 4-6, clamp 4-7, welding gun sleeve 4-8, locking plate 4-9, locking screw 4-10, rotating shaft 4-11, welding gun clamp 4-12, laser tracking probe 5, recovery pipe 6. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the accompanying drawings.

[0031] A composite welding device for plate tailor welding comprises a mounting frame 1, a plasma arc welding gun 2, a submerged arc welding gun 3, a laser tracking probe 5 and a recovery pipe 6. The plasma arc welding gun 2 is used to perform plasma arc welding on the plates, the submerged arc welding gun 3 is used to perform submerged arc welding on the plates, the laser tracking probe 5 is used to obtain weld information between the plates, and the recovery pipe 6 is used to recover the flux required for submerged arc welding. The laser tracking probe 5, the plasma arc welding gun 2, the submerged arc welding gun 3 and the recovery pipe 6 are arranged on the mounting frame in sequence, and the laser tracking probe 5, the plasma arc welding gun 2, the submerged arc welding gun 3 and the recovery pipe 6 are located in the same straight line, so that the plasma arc welding gun 2 and the submerged arc welding gun 3 can weld the plates while obtaining weld information, thereby improving welding accuracy and welding efficiency.

[0032] Plasma arc welding uses the high energy density beam of plasma arc as the welding heat source for fusion welding. The welding energy is relatively concentrated, which makes the welding depth larger. Plasma arc welding is used for low welding to weld the weld seam of the plate, and then submerged arc welding is used to fill and cover the groove position of the plate, so that welding can be completed without turning the plate over.

[0033] The mounting frame 1 includes a mounting rod 1-1, a connecting bracket 1-2, at least two slide rails 1-3 and two side rods 1-4. The two side rods 1-4 are arranged vertically, and the two slide rails 1-3 are fixed to the side rods 1-4 by screws to form a rectangular mounting frame. Connecting blocks 1-5 are installed on the two side ends of the side rods 1-4, and connecting columns 1-6 are provided on the connecting blocks 1-5. An embracing hole 1-7 is provided on the connecting bracket 1-2. The connecting column 1-6 is installed in the embracing hole 1-7. The length of the connecting column 1-6 is less than the axial length of the embracing hole 1-7. A limiting screw 1-8 is provided on the connecting column 1-6, which abuts against the connecting bracket 1-2 through the limiting screw 1-8, and the limiting screw 1-8 can be loosened to facilitate the adjustment of the mounting position of the mounting frame and the connecting bracket 1-2, thereby improving the assembly accuracy of the mounting frame 1, ensuring that the plasma arc welding gun 2, submerged arc welding gun 3 and laser tracking probe 5 on the mounting frame 1 can be set directly opposite the weld, thereby improving welding accuracy. Mounting rod 1-1 is provided with an adapter block 1-9, to which connecting bracket 1-2 is adjustably mounted via a spin block 1-10. Spin block 1-10, similar in structure to a screw, secures the relative position of connecting bracket 1-2 and mounting plate 1-1. Probe mounting posts 1-11 are mounted on side rods 1-4, and probe clamping blocks 1-12 are provided on probe mounting posts 1-11. Laser tracking probe 5 is mounted on probe clamping blocks 1-12. Adjusting the spacing between probe clamping blocks 1-12 and side rods 1-4 ensures that the laser tracking probe 5, plasma arc welding torch 2, and submerged arc welding torch 3 are aligned.

[0034] A connecting assembly 4 is adjustably installed on the slide rails 1-3, and the plasma arc welding gun 2 and the submerged arc welding gun 3 are installed on the mounting frame 1 through the connecting assembly 4. The connecting assembly 4 can slide and rotate relative to the mounting frame 1 to facilitate adjusting the inclination angle between the plasma arc welding gun 2, the submerged arc welding gun 3 and the plate. At the same time, the spacing between the plasma arc welding gun 2, the submerged arc welding gun 3 and the adjacent submerged arc welding guns 3 can also be adjusted.

[0035] The connecting assembly 4 includes a sliding connector 4-1 and a rotating connector 4-2. The sliding connector 4-1 is slidably installed on the slide rail 1-3, and the rotating connector 4-2 is rotatably installed on the sliding connector 4-1. The inclination angle of the plasma arc welding gun 2 or the submerged arc welding gun 3 is adjusted by rotating the rotating connector 4-2 relative to the sliding connector 4-1.

[0036] The sliding connection 4-1 includes a slider 4-3 and a sleeve 4-4. The rotating connection 4-2 is rotatably connected to the sleeve 4-4. The sleeve 4-4 is partially connected to the slider 4-3. Preferably, half of the semicircle of the sleeve 4-4 is connected to the slider 4-3, and the remaining circular surface of the sleeve 4-4 is separated from the slider 4-3 to facilitate deformation of the sleeve 4-4. An open groove 4-5 for the diameter of the sleeve 4-4 is provided on the sleeve 4-4, and a locking screw is provided at the open groove 4-5. The width of the open groove 4-5 is changed by the locking screw, so that the rotating connection 4-2 can be locked by the sleeve 4-4.

[0037] A dovetail groove is provided on the slider 4-3, and the slide rail 1-3 is installed in the dovetail groove. A locking member 4-6 is provided on the back of the slider 4-3, and the locking member 4-6 is adapted to the mounting frame 1. The slider 4-3 is locked on the mounting frame 1 through the cooperation of the locking member 4-6 and the mounting frame 1. Preferably, the locking member 4-6 includes a locking plate 4-9 and a locking screw 4-10. The locking plate 4-9 is fixed to the back of the slider 4-3, and the locking screw 4-10 is installed on the locking plate 4-9 through a thread, and the locking screw 4-10 abuts against the slide rail 1-3, thereby locking the slider 4-3.

[0038] The rotating connector 4-2 includes a clamp 4-7 and a welding gun sleeve 4-8. The clamp 4-7 is provided with a rotating shaft 4-11. The clamp 4-7 is rotatably connected to the sliding connector 4-1 via the rotating shaft 4-11. The angle of the plasma arc welding gun 2 or submerged arc welding gun 3 relative to the mounting frame 1 is adjusted by adjusting the angle of the clamp 4-7. The welding gun sleeve 4-8 is inserted into the clamp 4-7. The side wall of the welding gun sleeve 4-8 also has an opening to facilitate adjusting the inner diameter of the welding gun sleeve 4-8, thereby clamping the welding gun tightly. The welding gun sleeve 4-8 is an insulating member used to insulate the submerged arc welding gun 3.

[0039] In this embodiment, the plasma arc welding gun 2 is rotatably mounted on the sliding connector 4-1 via a welding gun clamp 4-12, and a rotating shaft is provided on the welding gun clamp 4-12 to facilitate the rotatable connection between the welding gun clamp 4-12 and the sliding connector 4-1.

[0040] A connecting assembly 4 is provided on each of the two slide rails 1-3 of the mounting frame 1. The submerged arc welding gun 3 is respectively connected to the two slide rails 1-3 through the two connecting assemblies 4. The submerged arc welding gun 3 is fixed by the two connecting assemblies 4 to ensure the installation stability of the submerged arc welding gun 3 and facilitate angle adjustment of the submerged arc welding gun 3.

[0041] A recovery pipe 6 is also installed on the mounting frame 1 through the connecting component 4. The recovery pipe 6 is used to recover excess flux after submerged arc welding. Preferably, the recovery pipe 6 is connected to a negative pressure device such as an exhaust fan or a vacuum cleaner.

[0042] The laser tracking probe 5, plasma arc welding gun 2, submerged arc welding gun 3, and recovery pipe 6 are arranged in sequence along the moving direction of the mounting frame 1, and at least ensure that the laser tracking probe 5, plasma arc welding gun 2, and submerged arc welding gun 3 are located in the same straight line. The mounting frame 1 is connected to the welding robot, and the mounting frame 1 is driven to move horizontally by the welding robot. The weld information is obtained by the laser tracking probe 5, and the plasma arc welding gun 2 is used to perform plasma arc welding on the plate, and the submerged arc welding gun 3 is used to perform submerged arc welding on the plate. The excess flux is recovered through the recovery pipe 6.

[0043] The submerged arc welding gun 3 includes a welding gun body 3-1 and a hopper 3-2. The hopper 3-2 is connected to the welding gun body 3-1 and is used to provide flux to the welding gun body 3-1. The welding gun body 3-1 is fixed in the welding gun sleeve 4-8.

[0044] The welding method of the composite welding device for plate tailor welding comprises the following steps:

[0045] S1, fix the laser tracking probe 5, plasma arc welding gun 2, and submerged arc welding gun 3 on the welding device in sequence. During the installation process, adjust the relative positions of the sliding connector 4-1, the rotating connector 4-2, and the probe clamping block 1-12 and rotate the limit screw 1-8 to ensure that the laser tracking probe 5, plasma arc welding gun 2, and submerged arc welding gun 3 are located in the same straight line, and adjust the spacing and angle relationship between the plasma arc welding gun 2 and submerged arc welding gun 3 according to the thickness of the welding plate. When the thickness of the plate is less than or equal to 8mm, welding is performed only by the plasma arc welding gun 2, and there is no need to adjust the plasma arc Regarding the positional relationship between the welding gun 2 and the submerged arc welding gun 3, when the plate thickness is greater than 8mm and less than or equal to 16mm, the submerged arc welding gun 3 is adjusted so that the wire tips of multiple submerged arc welding guns 3 are close together to ensure that multiple submerged arc welding guns 3 form a eutectic pool. At this time, the eutectic pool is fully coupled. In the fully coupled state, the spacing between the wire tips is 3-5mm. When there are special welding requirements, the spacing and angle relationship between adjacent plasma arc welding guns 2 are adjusted to achieve partial coupling and complete separation of the eutectic pool. That is, the molten pools formed by welding with multiple welding guns are in a partially overlapping or completely separated state. When the eutectic pool is partially coupled, the spacing between the wire tips is 5-12mm. When the eutectic pool is completely separated, the spacing between the wire tips is greater than 12mm.

[0046] S2, the welding device is started, the laser tracking probe 5, the plasma arc welding gun 2 and the submerged arc welding gun 3 are aligned to the weld by adjusting the connecting support 1-2, the weld information is obtained by the laser tracking probe 5, the welding device calculates the movement route of the welding device and the working quantity of the submerged arc welding gun 3 according to the weld information, the working quantity of the submerged arc welding gun 3 is positively correlated with the thickness of the plate, that is, when the weld depth is less than or equal to 8mm, the working quantity of the submerged arc welding gun 3 is 0, when the weld depth is greater than 8mm and less than or equal to 12mm, the working quantity of the submerged arc welding gun 3 is 1, when the weld depth is greater than 12mm and less than or equal to 16mm, the working quantity of the submerged arc welding gun 3 is 2, when the weld depth is greater than 16mm, secondary welding is needed by the welding mechanism, and the plasma arc welding gun 2 does not work in the secondary welding process.

[0047] S3, the plasma arc welding gun 2 and the submerged arc welding gun 3 work simultaneously, the plasma arc welding gun 2 is located at the front end of the submerged arc welding gun 3, the plate is welded by single-sided welding and double-sided forming through the plasma arc welding gun 2, and the weld is welded by submerged arc welding through the submerged arc welding gun 3.

[0048] In the specific use of the welding device, in step S1, the connecting line of the two submerged arc welding gun 3 can be arranged along the weld, or the connecting line of the two submerged arc welding gun 3 can be arranged perpendicular to the weld, the midpoint of the connecting line of the two submerged arc welding gun 3 is located on the same line as the laser tracking probe 5 and the plasma arc welding gun 2, so as to form a wide co-pool, thereby welding a wide weld.

[0049] When the thickness of the plate is greater than 8mm, a groove for submerged arc welding is arranged at the weld of the plate, so as to facilitate the submerged arc welding of the plate.

[0050] The above description of the disclosed embodiments enables those skilled in the art to carry out or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application; therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

[0051] Although the terms corresponding to the reference signs in the drawings are used more frequently herein, the possibility of using other terms is not excluded; these terms are used only to facilitate the description and explanation of the essence of the present application; any kind of additional limitation by interpreting them is contrary to the spirit of the present application.

Claims

1. A composite welding device for plate welding, characterized in that: The invention comprises a mounting frame (1), a plasma arc welding gun (2) for performing plasma arc welding on a plate, and at least one submerged arc welding gun (3) for performing submerged arc welding on the plate, wherein the plasma arc welding gun (2) and the submerged arc welding gun (3) are sequentially mounted on the mounting frame (1) along the moving direction of the composite welding device via a connecting assembly (4), so that the plasma arc welding gun (2) and the submerged arc welding gun (3) can sequentially weld the same side of the plate to be welded, and the connecting assembly (4) can slide and rotate relative to the mounting frame (1); The connecting assembly (4) comprises a sliding connecting member (4-1) slidably connected to the mounting frame (1) and a rotating connecting member (4-2) for mounting a plasma arc welding gun (2) or a submerged arc welding gun (3), wherein the rotating connecting member (4-2) is rotatably mounted on the sliding connecting member (4-1) so as to adjust the tilt angle of the plasma arc welding gun (2) or the submerged arc welding gun (3) by rotating the connecting member (4-2); The sliding connection member (4-1) comprises a slider (4-3) slidably connected to the mounting frame (1), and a sleeve (4-4) for connecting to the rotating connection member (4-2); the sleeve (4-4) is partially connected to the slider (4-3); an opening groove (4-5) for the diameter of the sleeve (4-4) is provided on the sleeve (4-4); and a locking member (4-6) adapted to the mounting frame (1) is installed on the slider (4-3) to lock the slider (4-3) on the mounting frame (1); The welding method based on the composite welding device comprises the following steps: S1, fixing the laser tracking probe (5), the plasma arc welding gun (2), and the submerged arc welding gun (3) on the welding device in sequence along the welding direction, and adjusting the spacing and angle relationship between the plasma arc welding gun (2) and the submerged arc welding gun (3) according to welding requirements, so as to achieve complete coupling, partial coupling, or complete separation of the eutectic pool according to welding requirements; S2, ensuring that the straight line where the laser tracking probe (5), the plasma arc welding gun (2), and the submerged arc welding gun (3) are located is on the same straight line as the weld seam of the plate to be welded, starting the welding device, obtaining weld seam information through the laser tracking probe (5), and calculating the movement route of the welding device and the number of operations of the submerged arc welding gun (3) based on the weld seam information; S3, the plasma arc welding gun (2) and the submerged arc welding gun (3) work simultaneously, the plasma arc welding gun (2) is located at the front end of the submerged arc welding gun (3), the plate is welded by the plasma arc welding gun (2), and then the weld is submerged arc welded by the submerged arc welding gun (3).

2. A composite welding device for plate tailor welding according to claim 1, characterized in that: The rotating connection member (4-2) comprises a clamp (4-7) for rotatably mounting a plasma arc welding gun (2) or a submerged arc welding gun (3) and a welding gun sleeve (4-8) for mounting the plasma arc welding gun (2) or the submerged arc welding gun (3); the clamp (4-7) is rotatably connected to the sliding connection member (4-1), and the welding gun sleeve (4-8) is inserted into the clamp (4-7).

3. The hybrid welding device for plate tailor welding according to claim 1, characterized in that: Two connection assemblies (4) are installed at different heights of the submerged arc welding gun (3), and the submerged arc welding gun (3) is adjustably mounted on the mounting frame (1) via the two connection assemblies (4).

4. The hybrid welding device for plate tailor welding according to claim 1, characterized in that: A laser tracking probe (5) for acquiring weld seam information is also mounted on the mounting frame (1), and the laser tracking probe (5) is arranged at the front end of the plasma arc welding gun (2).

5. The hybrid welding device for plate tailor welding according to claim 1, characterized in that: A recovery pipe (6) for recovering flux is also installed on the mounting frame (1), and the recovery pipe (6) is arranged behind the submerged arc welding gun.

6. The hybrid welding device for plate tailor welding according to claim 1, characterized in that: In step S2, the number of operations of the submerged arc welding gun (3) is positively correlated with the thickness of the plate.

7. The hybrid welding device for plate tailor welding according to claim 1, characterized in that: The plate is provided with a groove for submerged arc welding at the weld of the plate according to the thickness of the plate.

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