Laser welding positioning tooling and welding method for thin plate sandwich structure

Abstract

A laser welding positioning tool for a thin-plate sandwich structure includes a core plate positioning assembly, an upper cover plate positioning assembly, and a lower cover plate positioning assembly; the core plate positioning assembly includes a left channel steel, a core plate positioning channel steel, a core plate clamping cylinder or hydraulic cylinder, a connecting plate, a right upper beam, a right lower beam, a right front longitudinal beam, and a right rear longitudinal beam; the upper cover plate positioning assembly includes an upper beam, an upper cover plate clamping cylinder or hydraulic cylinder; and the lower cover plate positioning assembly includes a lower beam, a lower cover plate clamping cylinder or hydraulic cylinder. A welding method is also provided. The laser welding positioning tool adopts a modular design, with the main body welded and fixed, and the core plate positioning channel steel can be quickly replaced, reducing maintenance time; the cylinder or hydraulic cylinder is appropriately arranged, and the core plate positioning accuracy is high, ensuring the fitting gap between the upper and lower cover plates and the core plate, thereby improving welding reliability; laser welding follows the principle of welding from the center to both sides and alternating welding from the upper and lower sides, and the welding deformation of the workpiece is significantly controlled.

Description

Technical Field

[0001] The invention belongs to the field of ship tooling, and in particular relates to a laser welding positioning tooling and a welding method for a thin plate sandwich structure. Background Art

[0002] Currently, traditional ship frame structures, such as lightweight bulkheads and main transverse bulkheads, achieve increased structural rigidity by welding angle steel, channel steel, and T-shaped steel onto the plate. However, these ship frame structures occupy a large space and have low strength at constant weight. Therefore, the trend is to replace these structures with thin-plate sandwich structures. Compared with traditional ship frame structures, thin-plate sandwich structures offer the advantages of weight reduction, space saving, and noise reduction. At constant stiffness, thin-plate sandwich structures can reduce weight by 25% to 40%, reduce space by 30% to 55%, shorten installation time, and offer flexible application options.

[0003] However, existing thin-plate sandwich structures use traditional arc welding, which results in significant thermal stress and severe post-weld deformation. Conventional clamping methods, however, struggle to meet the gap requirements of laser welding, resulting in poor weld surface aesthetics and substandard bonding. Summary of the Invention

[0004] In view of the above problems, the present invention provides a laser welding positioning tool and a welding method for a thin plate sandwich structure.

[0005] The object of the present invention can be achieved by the following technical solutions: A laser welding positioning tool for a thin plate sandwich structure, comprising a core plate positioning assembly, an upper cover plate positioning assembly, and a lower cover plate positioning assembly;

[0006] The core plate positioning assembly includes a left channel steel, a core plate positioning channel steel, a core plate pressing cylinder or a hydraulic cylinder, a connecting plate, a right upper beam, a right lower beam, a right front longitudinal beam, and a right rear longitudinal beam; the left channel steel extends front and back and the opening is arranged to the left, and a plurality of the core plate positioning channel steels are arranged at equal intervals front and back, and each core plate positioning channel steel extends left and right and the opening is arranged to the front or rear, and the left end of each core plate positioning channel steel is connected to the left channel steel by a bolt, and the right end is connected to a vertically arranged connecting plate by a bolt, and a plurality of core plate pressing cylinders or hydraulic cylinders are distributed in the core plate positioning channel steel, and the piston ends of the core plate pressing cylinders or hydraulic cylinders are arranged in the same direction as the openings of the core plate positioning channel steels, and the right upper beam and the right lower beam both extend front and back and are connected through the right front longitudinal beam and the right rear longitudinal beam distributed front and back, and the right upper beam and the right lower beam are respectively connected to the upper end and lower end of each connecting plate by bolts;

[0007] The upper cover plate positioning assembly includes an upper beam and an upper cover plate pressing cylinder or a hydraulic cylinder; a plurality of the upper beams are arranged on the upper side of the core plate positioning assembly and are arranged at equal intervals front to back, each upper beam extends left to right and its two ends are respectively connected to the upper flange of the left channel steel and the right upper beam, and more than two upper cover plate pressing cylinders or hydraulic cylinders are distributed on the bottom surface of the upper beam, and the piston end of each upper cover plate pressing cylinder or hydraulic cylinder is arranged downward;

[0008] The lower cover plate positioning assembly includes a lower beam and a lower cover plate pressing cylinder or hydraulic cylinder; a plurality of the lower beams are arranged on the lower side of the core plate positioning assembly and are arranged at equal intervals front to back, each lower beam extends left to right and its two ends are respectively connected to the lower flange of the left channel steel and the right lower beam, and more than two lower cover plate pressing cylinders or hydraulic cylinders are distributed on the top surface of the lower beam, and the piston end of each lower cover plate pressing cylinder or hydraulic cylinder is arranged upward;

[0009] Wherein, a core plate limiting block is provided at the left end of the back side of the core plate positioning channel steel;

[0010] The left end of the upper flange of the core plate positioning channel steel is provided with left and right limit blocks of the upper cover plate, and the upper cover plate positioning assembly also includes an upper front connecting beam and an upper rear connecting beam, the upper front connecting beam and the upper rear connecting beam are respectively arranged on the front and rear sides of the plurality of upper beams, the upper front connecting beam and the upper rear connecting beam both extend left and right and the two ends are respectively connected to the upper flange of the left channel steel and the right upper beam, and the bottom surface of the upper front connecting beam or the upper rear connecting beam is provided with front and rear limit blocks of the upper cover plate;

[0011] The left end of the lower flange of the core plate positioning channel steel is provided with left and right limit blocks of the lower cover plate. The lower cover plate positioning assembly also includes a lower front connecting beam and a lower rear connecting beam. The lower front connecting beam and the lower rear connecting beam are respectively arranged on the front and rear sides of multiple lower beams. The lower front connecting beam and the lower rear connecting beam both extend left and right and the two ends are respectively connected to the lower flange of the left channel steel and the right lower beam. The bottom surface of the lower front connecting beam or the lower rear connecting beam is provided with front and rear limit blocks of the lower cover plate.

[0012] Furthermore, a top block is provided on the piston end of the core plate pressing cylinder or hydraulic cylinder, the piston end of the upper cover plate pressing cylinder or hydraulic cylinder, and the piston end of the lower cover plate pressing cylinder or hydraulic cylinder.

[0013] Furthermore, core plate positioning channel steel sealing plates are provided at both ends of the core plate positioning channel steel.

[0014] Furthermore, reinforcing ribs are provided in the core plate positioning channel steel.

[0015] Furthermore, the connecting edge between the back surface of the core plate positioning channel steel and the lower flange is provided with a chamfer.

[0016] Furthermore, the right upper beam and the right lower beam are both channel steels with openings facing right, and the right upper beam and the right lower beam are respectively provided with a right upper beam sealing plate and a right lower beam sealing plate.

[0017] Furthermore, the upper beam and the lower beam are both I-beams.

[0018] A method for welding a thin plate sandwich structure, using the laser welding positioning tool for the thin plate sandwich structure, comprises the following steps:

[0019] (1) Remove the connecting plate from the core plate positioning channel steel, the right upper beam, and the right lower beam, place the lower cover plate on multiple lower cover plate pressing cylinders or hydraulic cylinders, place multiple core plates on the back of multiple core plate positioning channel steels, place the upper cover plate on the upper edge of multiple core plates, reinstall the connecting plate, and mark the position of the core plate on the lower cover plate and the upper cover plate;

[0020] (2) After the lower cover is positioned by the front and rear limit blocks and the left and right limit blocks of the lower cover, the lower cover is pressed by the lower cover pressing cylinder or hydraulic cylinder to press the lower cover onto the lower flanges of the core plate positioning channel steels;

[0021] (3) After the core plate is positioned by the core plate limit block on the back of the core plate positioning channel steel, the core plate pressing cylinder or hydraulic cylinder presses the core plate onto the back of the core plate positioning channel steel;

[0022] (4) After the upper cover plate is positioned by the upper cover plate front and rear limit blocks and the upper cover plate left and right limit blocks, the upper cover plate pressing cylinder or hydraulic cylinder presses the upper cover plate onto the upper edge of the multiple core plates;

[0023] (5) After laser spot welding both ends of all welds to be welded, laser welding is performed according to the principle of welding from the middle to both sides and alternating welding from top to bottom;

[0024] (6) Remove the connecting plate and take out the welded workpiece from the right side.

[0025] Furthermore, in step (5), when each weld is completed, compressed air is introduced into the welding position, and welding of the next station is started after the weld is cooled to room temperature.

[0026] Furthermore, before step (1), the laser welding positioning fixture of the thin plate sandwich structure is installed on the head and tail frame positioner through the upper front connecting beam, the upper rear connecting beam, the lower front connecting beam, and the upper rear connecting beam.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The laser welding positioning fixture adopts a modular design. The main body is fixed by welding. The core plate positioning channel steel is the main component to ensure the positioning accuracy of the workpiece. The core plate positioning channel steel provides the positioning of the core plate and the compression of the next core plate, and also provides the positioning of the lower cover plate. The two ends are connected by bolts. When the core plate positioning channel steel is worn or the accuracy is insufficient, it can be quickly replaced to reduce maintenance time.

[0029] 2. Use air cylinders or hydraulic cylinders to press the workpiece. All pressing cylinders or hydraulic cylinders are installed on the laser welding positioning fixture by bolt connection, which is convenient for maintenance and replacement;

[0030] 3. The right end of the core plate positioning channel steel is connected to the right rectangular frame with a connecting plate. After removing the connecting plate and loosening all the clamping cylinders or hydraulic cylinders, the welded thin plate sandwich structure can be taken out from the right side, and the workpiece assembly can also be easily carried out on the right side;

[0031] 4. The laser welding positioning tooling is installed on the head and tail frame positioner through the upper front connecting beam, upper rear connecting beam, lower front connecting beam, and upper rear connecting beam, which can achieve rapid flipping;

[0032] 5. The core plate positioning channel steel in the laser welding positioning fixture is longer than the length of the workpiece. The back of the extended part of the core plate positioning channel steel can be used as the laser welding positioning reference surface, which reduces the marking time;

[0033] 6. The upper and lower sides of the core plate are compressed by compression cylinders or hydraulic cylinders. Each core plate has at least 12 compression cylinders or hydraulic cylinders for compression, with high positioning accuracy. The upper cover plate and the lower cover plate have at least 3 compression cylinders or hydraulic cylinders between each two core plates for compression. The fitting gap between the upper cover plate and the core plate and the fitting gap between the lower cover plate and the core plate can be effectively guaranteed, thereby improving welding reliability.

[0034] 7. A welding method for thin-plate sandwich structures is provided. After the workpiece is clamped, laser spot welding is performed on both ends of all welds. Then, laser welding is performed according to the principle of welding from the middle to both sides and alternating welding from the top to the bottom. Compared with single-sided continuous welding, the welding deformation is significantly controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic structural diagram of the laser welding positioning tooling of the present invention.

[0036] Figure 2 for Figure 1 Right view of .

[0037] Figure 3 for Figure 1 Top view of .

[0038] Figure 4 for Figure 1 Vertical cross-section of .

[0039] Figure 5 Schematic diagram of the welding sequence for laser welding one side of a thin-plate sandwich structure.

[0040] Figure 6 for Figure 5 Schematic diagram of the welding sequence for the other side of the post-laser-welded thin-plate sandwich structure.

[0041] Figures 1 to 4 The parts are numbered as follows:

[0042] 1 Left channel steel

[0043] 2 core plate positioning channel steel

[0044] 3 core plate pressing cylinder or hydraulic cylinder

[0045] 4 connecting plates

[0046] 5Right upper beam

[0047] 6 Right lower beam

[0048] 7Right front longitudinal beam

[0049] 8Right rear longitudinal beam

[0050] 9-core board limit block

[0051] 10 core board positioning channel steel sealing plate

[0052] 11 Reinforcement ribs

[0053] 12 Right upper beam sealing plate

[0054] 13 Right lower beam sealing plate

[0055] 14 Raising the beam

[0056] 15 Upper cover pressing cylinder or hydraulic cylinder

[0057] 16 Upper front connecting beam

[0058] 17 Upper rear connecting beam

[0059] 18 Front and rear limit blocks of upper cover

[0060] 19 Left and right limit blocks of upper cover

[0061] 20 Lower beam

[0062] 21 Lower cover pressing cylinder or hydraulic cylinder

[0063] 22 left and right limit blocks of the lower cover. DETAILED DESCRIPTION

[0064] The following describes the specific embodiments of the present invention in detail in conjunction with the accompanying drawings so that those skilled in the art can more clearly understand how to practice the present invention. Although the present invention has been described in conjunction with its preferred embodiments, these embodiments are merely illustrative, rather than limiting, the scope of the present invention.

[0065] See also Figures 1 to 4 A laser welding positioning tool for a thin plate sandwich structure includes a core plate positioning component, an upper cover plate positioning component, and a lower cover plate positioning component.

[0066] The core plate positioning assembly includes a left channel steel 1, a core plate positioning channel steel 2, a core plate pressing cylinder or hydraulic cylinder 3, a connecting plate 4, a right upper beam 5, a right lower beam 6, a right front longitudinal beam 7, and a right rear longitudinal beam 8.

[0067] The left channel steel 1 extends in the front-to-back direction and is opened to the left; a plurality of the core plate positioning channel steels 2 are arranged at equal intervals front to back, and each core plate positioning channel steel 2 extends in the left-to-right direction and is opened to the front, and the left end of each core plate positioning channel steel 2 is connected to the left channel steel 1 by a bolt, and the right end of the core plate positioning channel steel 2 is connected to a vertically arranged connecting plate 4 by a bolt, and a plurality of core plate pressing cylinders or hydraulic cylinders 3 arranged in a rectangular array are distributed in the core plate positioning channel steel 2. In this embodiment, each core plate positioning channel steel 2 is provided with 12 core plate pressing cylinders or hydraulic cylinders 3 arranged in a 2*6 array, and each core plate The piston end of the clamping cylinder or hydraulic cylinder 3 is set in the same direction as the opening of the core plate positioning channel steel 2, and is used to press the core plate onto the core plate positioning channel steel 2 on the front side. Of course, the opening of the core plate positioning channel steel 2 and the piston end of the core plate clamping cylinder or hydraulic cylinder 3 can also be set toward the rear, which is not shown here by the picture; the right upper beam 5 and the right lower beam 6 are distributed up and down and both extend in the front and rear directions. The right upper beam 5 and the right lower beam 6 are welded together through the right front longitudinal beam 7 and the right rear longitudinal beam 8 distributed front and back, and the right upper beam 5 and the right lower beam 6 are respectively connected to the upper and lower ends of each connecting plate 4 by bolts.

[0068] Among them, a core plate limiting block 9 is welded to the left end of the back side of the core plate positioning channel steel 2; a top block is provided at the piston end of the core plate pressing cylinder or hydraulic cylinder 3; a core plate positioning channel steel sealing plate 10 is welded to both ends of the core plate positioning channel steel 2; a reinforcing rib 11 is welded inside the core plate positioning channel steel 2; the back side and the lower flange of the core plate positioning channel steel 2 are milled flat, respectively used to ensure the positioning accuracy of the core plate and the lower cover plate; the connecting edge of the back side and the lower flange of the core plate positioning channel steel 2 is chamfered to avoid the influence of the corners of the core plate positioning channel steel 2 on the weld. The right upper beam 5 and the right lower beam 6 are channel steels with the opening facing right, and the right upper beam sealing plate 12 and the right lower beam sealing plate 13 are welded to the right upper beam 5 and the right lower beam 6 respectively.

[0069] The upper cover plate positioning assembly includes an upper beam 14 and an upper cover plate pressing cylinder or hydraulic cylinder 15. Multiple upper beams 14 are arranged on the upper side of the core plate positioning assembly and are arranged at equal intervals in the front and rear directions. Each upper beam 14 extends in the left and right directions. The two ends of the upper beam 14 are respectively welded to the upper flange of the left channel steel 1 and the right upper beam 5. There are more than two upper cover plate pressing cylinders or hydraulic cylinders 15 distributed on the left and right sides of the bottom surface of the upper beam 14. The piston end of each upper cover plate pressing cylinder or hydraulic cylinder 15 is set downward, which is used to press the upper cover plate onto the upper flange of multiple core plate positioning channel steels 2.

[0070] Among them, the upper beam 14 is an I-beam; the front and rear sides of the multiple upper beams 14 are respectively provided with an upper front connecting beam 16 and an upper rear connecting beam 17, and the upper front connecting beam 16 and the upper rear connecting beam 17 are extended in the left and right directions, and the two ends of the upper front connecting beam 16 and the upper rear connecting beam 17 are respectively welded to the upper flange of the left channel steel 1 and the right upper beam 5; the front and rear limit blocks 18 of the upper cover plate are welded to the bottom surface of the upper front connecting beam 16 or the upper rear connecting beam 17; the left end of the upper flange of each core plate positioning channel steel 2 is welded to the upper cover plate left and right limit blocks 19; the piston end of the upper cover plate clamping cylinder or hydraulic cylinder 15 is provided with a top block.

[0071] The lower cover plate positioning assembly includes a lower beam 20 and a lower cover plate pressing cylinder or hydraulic cylinder 21. Multiple lower beams 20 are arranged on the lower side of the core plate positioning assembly and are arranged at equal intervals in the front and rear directions. Each lower beam 20 extends in the left and right directions. The two ends of the lower beam 20 are respectively welded to the lower flange of the left channel steel 1 and the right lower beam 6. There are more than two lower cover plate pressing cylinders or hydraulic cylinders 21 distributed on the top surface of the lower beam 20. The piston end of each lower cover plate pressing cylinder or hydraulic cylinder 21 is set upward, which is used to press the lower cover plate against the lower flange of multiple core plate positioning channel steels 2.

[0072] Among them, the lower beam 20 is an I-beam; the front and rear sides of the multiple lower beams 20 are respectively provided with a lower front connecting beam and a lower rear connecting beam, and the lower front connecting beam and the lower rear connecting beam are extended in the left and right directions, and the two ends of the lower front connecting beam and the lower rear connecting beam are respectively welded to the lower flange of the left channel steel 1 and the right lower beam 6; the front and rear limit blocks of the lower cover plate are welded on the top surface of the lower front connecting beam or the lower rear connecting beam; the left end of the lower flange of each core plate positioning channel steel 2 is welded with the left and right limit blocks 22 of the lower cover plate; the piston end of the lower cover plate clamping cylinder or hydraulic cylinder 21 is provided with a top block.

[0073] In actual implementation, a small hole is opened between every two core plate positioning channel steels 2 on the left channel steel 1 for arranging a gas path or a liquid path.

[0074] Before welding, remove the primer from the steel plate in the welding area and clean the welding area with acetone. Install the laser welding positioning fixture on the head and tail frame positioner through the upper front connecting beam 16, the upper rear connecting beam 17, the lower front connecting beam, and the upper rear connecting beam 17. The head and tail frame positioner is used to quickly flip the laser welding positioning fixture, which facilitates the laser welding operation.

[0075] A method for welding a thin plate sandwich structure comprises the following steps:

[0076] (1) Remove the connecting plate 4 from the core plate positioning channel steel 2, the right upper beam 5, and the right lower beam 6, and place the lower cover plate, multiple core plates, and the upper cover plate in the corresponding positions of the laser welding positioning fixture respectively. Specifically, place the lower cover plate on the lower cover plate pressing cylinder or hydraulic cylinder 21, place the multiple core plates on the back of the multiple core plate positioning channel steels 2, and place the upper cover plate on the upper edge of the multiple core plates. Then reinstall the connecting plate 4 on the core plate positioning channel steel 2, the right upper beam 5, and the right lower beam 6 to fix the multiple core plate positioning channel steels 2. Then, mark the position of the core plate on the lower cover plate and the upper cover plate. Among them, when installing the core plate in this embodiment, two equal-length assembled core plates are placed on the back of each core plate positioning channel steel 2 to ensure that the top block of the core plate clamping cylinder or hydraulic cylinder 3 located in the middle can be pressed against the junction of the two equal-length assembled core plates, and to ensure that the positioning weld on the weld is on the same vertical plane as the position of the top block of the corresponding core plate clamping cylinder or hydraulic cylinder 3 below when it is pressed, so as to reduce welding deformation.

[0077] (2) After the lower cover is positioned by the lower cover front and rear limit blocks and the lower cover left and right limit blocks 22, the lower cover pressing cylinder or hydraulic cylinder 21 is turned on to press the lower cover onto the lower flanges of the plurality of core plate positioning channel steels 2.

[0078] (3) After the core plate is positioned by the core plate limit block 9 on the back of the core plate positioning channel steel 2, the core plate pressing cylinder or hydraulic cylinder 3 is turned on to press the core plate onto the back of the core plate positioning channel steel 2.

[0079] (4) After the upper cover is positioned by the upper cover front and rear limit blocks 18 and the upper cover left and right limit blocks 19, the upper cover pressing cylinder or hydraulic cylinder 15 is turned on to press the upper cover onto the upper edges of the multiple core plates.

[0080] (5) Laser spot weld both ends of all welds to be welded, and then perform laser welding according to the principle of welding from the middle to both sides and welding alternately from top to bottom to control welding deformation. The welding sequence can be found in Figure 5 and Figure 6 .

[0081] During the initial exploration of the process, each weld started from one side of the upper and lower cover plates, and the robot drove the laser head to pass through multiple positioning welds in sequence during the movement.

[0082] In order to reduce the core plate processing error, a whole core plate can be used to replace two equal-length assembled core plates; if it is not possible to replace two core plates with one core plate, when welding a single weld, find the position of the junction of the two equal-length assembled core plates on the upper cover plate and the lower cover plate, and start welding from this position (i.e. the center of the weld length) to both sides in sequence.

[0083] At the end of each weld, compressed air is introduced into the welding area, and the welding of the next station is started after the weld has cooled to room temperature.

[0084] (6) Remove the connecting plate 4 and take out the welded workpiece from the right side.

[0085] It should be noted that the core plate is prone to deformation when turning over after welding. When transporting, two people should be responsible for supporting the center area of the upper and lower cover plates to prevent excessive deformation of this area.

[0086] It should be noted that the present invention, having been fully described, is susceptible to numerous variations and modifications, and is not limited to the specific embodiments described above. The foregoing embodiments are intended to illustrate the present invention, not to limit it. In short, the scope of protection of the present invention encompasses any such variations, substitutions, and modifications as would be apparent to one of ordinary skill in the art.

Claims

1. A laser welding positioning tool for a thin plate sandwich structure, characterized in that: Including core plate positioning assembly, upper cover plate positioning assembly, lower cover plate positioning assembly; The core plate positioning assembly includes a left channel steel, a core plate positioning channel steel, a core plate pressing cylinder or a hydraulic cylinder, a connecting plate, a right upper beam, a right lower beam, a right front longitudinal beam, and a right rear longitudinal beam; the left channel steel extends front and back and the opening is arranged to the left, and a plurality of the core plate positioning channel steels are arranged at equal intervals front and back, and each core plate positioning channel steel extends left and right and the opening is arranged to the front or rear, and the left end of each core plate positioning channel steel is connected to the left channel steel by a bolt, and the right end is connected to a vertically arranged connecting plate by a bolt, and a plurality of core plate pressing cylinders or hydraulic cylinders are distributed in the core plate positioning channel steel, and the piston ends of the core plate pressing cylinders or hydraulic cylinders are arranged in the same direction as the openings of the core plate positioning channel steels, and the right upper beam and the right lower beam both extend front and back and are connected through the right front longitudinal beam and the right rear longitudinal beam distributed front and back, and the right upper beam and the right lower beam are respectively connected to the upper end and lower end of each connecting plate by bolts; The upper cover plate positioning assembly includes an upper beam and an upper cover plate pressing cylinder or a hydraulic cylinder; a plurality of the upper beams are arranged on the upper side of the core plate positioning assembly and are arranged at equal intervals front to back, each upper beam extends left to right and its two ends are respectively connected to the upper flange of the left channel steel and the right upper beam, and more than two upper cover plate pressing cylinders or hydraulic cylinders are distributed on the bottom surface of the upper beam, and the piston end of each upper cover plate pressing cylinder or hydraulic cylinder is arranged downward; The lower cover plate positioning assembly includes a lower beam and a lower cover plate pressing cylinder or hydraulic cylinder; a plurality of the lower beams are arranged on the lower side of the core plate positioning assembly and are arranged at equal intervals front to back, each lower beam extends left to right and its two ends are respectively connected to the lower flange of the left channel steel and the right lower beam, and more than two lower cover plate pressing cylinders or hydraulic cylinders are distributed on the top surface of the lower beam, and the piston end of each lower cover plate pressing cylinder or hydraulic cylinder is arranged upward; Wherein, a core plate limiting block is provided at the left end of the back side of the core plate positioning channel steel; The left end of the upper flange of the core plate positioning channel steel is provided with left and right limit blocks of the upper cover plate, and the upper cover plate positioning assembly also includes an upper front connecting beam and an upper rear connecting beam, the upper front connecting beam and the upper rear connecting beam are respectively arranged on the front and rear sides of the plurality of upper beams, the upper front connecting beam and the upper rear connecting beam both extend left and right and the two ends are respectively connected to the upper flange of the left channel steel and the right upper beam, and the bottom surface of the upper front connecting beam or the upper rear connecting beam is provided with front and rear limit blocks of the upper cover plate; The left end of the lower flange of the core plate positioning channel steel is provided with left and right limit blocks of the lower cover plate. The lower cover plate positioning assembly also includes a lower front connecting beam and a lower rear connecting beam. The lower front connecting beam and the lower rear connecting beam are respectively arranged on the front and rear sides of multiple lower beams. The lower front connecting beam and the lower rear connecting beam both extend left and right and the two ends are respectively connected to the lower flange of the left channel steel and the right lower beam. The bottom surface of the lower front connecting beam or the lower rear connecting beam is provided with front and rear limit blocks of the lower cover plate.

2. The laser welding positioning tool for a thin plate sandwich structure according to claim 1, characterized in that: A top block is provided on the piston end of the core plate pressing cylinder or hydraulic cylinder, the piston end of the upper cover plate pressing cylinder or hydraulic cylinder, and the piston end of the lower cover plate pressing cylinder or hydraulic cylinder.

3. The laser welding positioning tool for a thin plate sandwich structure according to claim 1, characterized in that: Core plate positioning channel steel sealing plates are provided at both ends of the core plate positioning channel steel.

4. The laser welding positioning tool for a thin plate sandwich structure according to claim 1, characterized in that: Reinforcement ribs are provided in the core plate positioning channel steel.

5. The laser welding positioning tool for a thin plate sandwich structure according to claim 1, characterized in that: The connecting edge between the back surface of the core plate positioning channel steel and the lower flange is provided with a chamfer.

6. The laser welding positioning tool for a thin plate sandwich structure according to claim 1, characterized in that: The right upper beam and the right lower beam are both channel steels with openings facing right. The right upper beam and the right lower beam are respectively provided with a right upper beam sealing plate and a right lower beam sealing plate.

7. The laser welding positioning tool for a thin plate sandwich structure according to claim 1, characterized in that: The upper beam and the lower beam are both I-beams.

8. A method for welding a thin plate sandwich structure, characterized in that: The laser welding positioning tool for the thin plate sandwich structure according to any one of claims 1 to 7 comprises the following steps: (1) Remove the connecting plate from the core plate positioning channel steel, the right upper beam, and the right lower beam, place the lower cover plate on multiple lower cover plate pressing cylinders or hydraulic cylinders, place multiple core plates on the back of multiple core plate positioning channel steels, place the upper cover plate on the upper edge of multiple core plates, reinstall the connecting plate, and mark the position of the core plate on the lower cover plate and the upper cover plate; (2) After the lower cover is positioned by the front and rear limit blocks and the left and right limit blocks of the lower cover, the lower cover is pressed by the lower cover pressing cylinder or hydraulic cylinder to press the lower cover onto the lower flanges of the core plate positioning channel steels; (3) After the core plate is positioned by the core plate limit block on the back of the core plate positioning channel steel, the core plate pressing cylinder or hydraulic cylinder presses the core plate onto the back of the core plate positioning channel steel; (4) After the upper cover plate is positioned by the upper cover plate front and rear limit blocks and the upper cover plate left and right limit blocks, the upper cover plate pressing cylinder or hydraulic cylinder presses the upper cover plate onto the upper edge of the multiple core plates; (5) After laser spot welding both ends of all welds to be welded, laser welding is performed according to the principle of welding from the middle to both sides and alternating welding from top to bottom; (6) Remove the connecting plate and take out the welded workpiece from the right side.

9. The welding method of the thin plate sandwich structure according to claim 8, characterized in that: In step (5), when each weld is completed, compressed air is introduced into the welding position, and the welding of the next station is started after the weld is cooled to room temperature.

10. The welding method of the thin plate sandwich structure according to claim 8 or 9, characterized in that: Before step (1), the laser welding positioning fixture of the thin plate sandwich structure is installed on the head and tail frame positioner through the upper front connecting beam, the upper rear connecting beam, the lower front connecting beam and the upper rear connecting beam.

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