Underwater Reinforcing Steel and Concrete Composite Printing Device and Method

Abstract

This invention discloses an underwater composite printing device and method for reinforcing steel and concrete, comprising a component storage chamber, a guide rail moving unit, a robotic arm, an underwater concrete printing unit, and an underwater laser printing unit. The component storage chamber can float underwater at the location to be repaired. The guide rail moving unit is fixed around the component storage chamber. The robotic arm base is connected to a circular turntable on the guide rail moving unit. The underwater concrete printing unit consists of a drainage hood and a concrete printing nozzle, with its end connected to the end of the robotic arm. The underwater laser printing unit consists of a drainage hood and a laser printing nozzle, with its end connected to the robotic arm. The drainage hood utilizes high-pressure gas to form an air curtain, creating dry conditions underwater and providing favorable working conditions for the concrete printing and laser printing devices. This invention can simultaneously print reinforcing steel and concrete underwater, suitable for repairing various types of damage to underwater structures, resulting in underwater structures with higher strength after repair.

Description

Technical Field

[0001] This invention relates to the field of 3D printing technology, and in particular to an underwater composite printing device and method for steel bars and concrete. Background Technology

[0002] Underwater structures are constantly exposed to complex water flow, corrosion, and erosion environments, making them prone to structural damage such as cracks and spalling, significantly reducing their mechanical properties and posing safety hazards. Traditional repair techniques mainly rely on cofferdam drainage and underwater divers. Cofferdam drainage requires constructing temporary cofferdams and pumping out accumulated water to create a dry environment, resulting in long construction periods, high costs, and poor adaptability to large areas of water or deep water areas. Underwater repair by divers is limited by the low precision of manual operations, high operational risks, and difficulty in achieving precise repairs of complex structures.

[0003] In recent years, concrete 3D printing technology has been introduced into the field of underwater repair due to its moldless molding, flexibility, and high efficiency. For example, Chinese patent 202411243012.7 proposes direct repair using an underwater concrete printing nozzle, but it relies on surface guide rails for positioning, resulting in insufficient precision and failing to address the interference of the underwater environment on concrete hardening and molding. Chinese patent 202310724608.8 designed a waterproof concrete nozzle, which avoids the need for cofferdam drainage, but the concrete is still exposed to the water flow, easily leading to loose molding, insufficient strength, and a lack of steel reinforcement, thus limiting the durability of the repaired structure. Furthermore, while laser additive manufacturing technology can print metal structures, existing underwater repair technologies mostly focus on a single material (concrete or steel reinforcement), lacking the ability to simultaneously print composite materials, resulting in limited improvement in the mechanical properties of the repaired area. Simultaneously, factors such as water pressure and seepage in the underwater environment directly interfere with the deposition and curing of the printed material. Existing technologies, through the addition of protective agents or simple waterproof designs, cannot completely isolate the influence of the aquatic environment, thus restricting the quality and efficiency of repair. Summary of the Invention

[0004] Purpose of the Invention: The purpose of this invention is to address the problems of low efficiency and poor repair quality in current underwater printing repair technologies, which suffer from cracks and other defects that occur during long-term operation of underwater structures. This invention proposes an underwater composite printing device and method for steel reinforcement and concrete. Directly repairing damaged structures underwater avoids the economic losses associated with rebuilding. Compared to traditional drainage repair methods, it has less impact on the surrounding environment, lower construction difficulty, and reduces manpower, material resources, and economic losses. Simultaneous printing of steel reinforcement and concrete for underwater repair improves the mechanical properties and safety factor of damaged structures. The device has high-precision position adjustment capabilities, enabling accurate positioning and adjustment of the damaged area for repair.

[0005] Technical solution: To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The first aspect of this invention provides an underwater composite printing device for steel bars and concrete, comprising a parts storage chamber, a guide rail moving unit, a robotic arm, an underwater concrete printing unit, and an underwater laser printing unit. The parts storage chamber is suspended underwater at the location to be repaired. The guide rail moving unit is fixed around the parts storage chamber. The base of the robotic arm is connected to a circular turntable on the guide rail moving unit. The underwater concrete printing unit includes a first drainage hood and a concrete printing nozzle. The end of the underwater concrete printing unit is connected to the end of the robotic arm. The underwater laser printing unit includes a second drainage hood and a laser printing nozzle. The end of the underwater laser printing unit is connected to the robotic arm. The first drainage hood and / or the second drainage hood form an air curtain to create a dry environment underwater, providing dry conditions for printing concrete and steel bars.

[0007] Furthermore, the accessory storage compartment includes a guide rail bearing surface, a gas propulsion unit, a concrete silo, a steel bar silo, a battery, a gas cylinder, and a control center; the guide rail bearing surface is used to install the guide rail moving unit; the gas propulsion unit is used to drive the accessory storage compartment to adjust its position in the water; the gas cylinder stores high-pressure gas required for the formation of the air curtain by the first and / or second drainage hoods; the concrete silo stores repair materials required by the underwater concrete printing unit; the steel bar silo stores materials for printing steel bars required by the underwater laser printing unit; the battery powers the device; and the control center houses communication and remote control devices.

[0008] Furthermore, the guide rail moving unit includes an X-rail, a Y-rail, a guide rail slider, and a circular turntable. The X-rail is fixed to the guide rail bearing surface, and its overall length is longer than the guide rail bearing surface, providing more adjustment range in the X direction. The Y-rail is mounted on the X-rail, enabling free movement in the X direction. The guide rail slider is mounted on the Y-rail, enabling free movement in the Y direction. The circular turntable is fixed to the guide rail slider and can rotate 360°. The robotic arm is fixed to the circular turntable for rotational adjustment. The guide rail moving unit can provide precise adjustment for the robotic arm in the X, Y, and circumferential directions. When the accessory storage compartment reaches the repair position, the guide rail moving unit can adjust the underwater concrete printing unit and the underwater laser printing unit to a more precise position.

[0009] Furthermore, the robotic arm includes a base, a large arm, a small arm, an end effector, and a rotary joint. The base is fixed to the circular turntable, and the rotation of the turntable causes the robotic arm to adjust circumferentially. The large arm is connected to the base via the rotary joint, the small arm is connected to the large arm via the rotary joint, and the small arm is connected to the end effector via the rotary joint. The end effector is connected to the underwater concrete printing unit and the underwater laser printing unit. The robotic arm can precisely adjust the position of the underwater concrete printing unit and the underwater laser printing unit.

[0010] Furthermore, the underwater concrete printing unit includes a concrete nozzle, a spiral stirring rod, a first drainage cover, several first connecting screws, a first one-way valve, a first waterproof cover, and a motor compartment. The first drainage cover includes a lower connector, a middle connector, and an upper connector connected together by the first connecting screws. The interior of the first drainage cover includes three drainage cover modules, forming a tortuous gas circuit. The high-pressure gas from the first one-way valve is evenly dispersed in the circuit and sprayed out from the bottom of the first drainage cover, forming a frustum-shaped air curtain at the bottom of the first drainage cover, creating an underwater drying zone. The first one-way valve is installed at the reserved interface of the first drainage cover to provide one-way high-pressure gas. The spiral stirring rod is installed in the concrete nozzle to stir the concrete in the concrete nozzle and prevent the concrete from solidifying. The concrete nozzle is installed on the first drainage cover by the first connecting screws. The first waterproof cover is installed on the first drainage cover and the concrete nozzle to eliminate the gap between the drainage cover and the concrete nozzle and prevent water seepage. The motor compartment houses a motor that drives the spiral stirring rod to rotate. The motor compartment is connected to the first waterproof cover and the end connector of the robotic arm. The underwater concrete printing unit is used to achieve concrete printing repair under underwater drying conditions.

[0011] Furthermore, the underwater laser printing unit includes a laser printhead, a second drainage cover, a second one-way valve, a second waterproof cover, connectors, and several second connecting screws. The second drainage cover consists of a lower connector, a middle connector, and an upper connector. The three modules of the second drainage cover are assembled together in an upper-middle-lower order and fixed together by the second connecting screws, forming a tortuous gas circuit inside the second drainage cover. High-pressure gas enters the drainage cover through the second one-way valve, is evenly dispersed in the gas circuit, and then sprays out from the bottom of the second drainage cover, forming a frustum-shaped air curtain at the bottom of the second drainage cover to create an underwater drying zone. The second one-way valve is installed at the reserved interface of the second drainage cover to provide one-way high-pressure gas. The laser printhead is installed inside the second waterproof cover and has the function of printing steel bars underwater. The second waterproof cover is connected to the second drainage cover and the laser printhead. The connector is configured at the end of the laser printhead and cooperates with the end connector of the robotic arm to realize the position adjustment of the underwater laser printing unit. The laser printhead can realize the printing of steel bars under underwater drying conditions.

[0012] A second aspect of the present invention provides an underwater composite printing method for steel reinforcement and concrete based on the above-mentioned device. The method employs an underwater concrete printing unit and an underwater laser printing unit to alternately print and repair the steel reinforcement and concrete structures in layers on underwater damaged building structures. After the accessory storage compartment is submerged in water, it is adjusted to the repair area using a gas propulsion unit. The device uses the guide rail moving unit and the robotic arm to adjust the underwater laser printing unit to the corresponding damaged position and print the steel reinforcement. After the steel reinforcement printing is completed, the underwater concrete printing unit is adjusted to the position of the steel reinforcement using the guide rail moving unit and the robotic arm to perform concrete printing repair. The underwater concrete printing unit operates immediately following the underwater laser printing unit.

[0013] Furthermore, the method includes the following steps:

[0014] S1: After the accessory storage compartment is submerged in water, it is adjusted to the repair area using a gas thruster;

[0015] S2: The guide rail moving unit and the robotic arm mounted on the accessory storage compartment adjust the underwater laser printing unit and the underwater concrete printing unit to the corresponding damage position;

[0016] S3: The one-way valve inputs high-pressure gas, which enters the gas circuit inside the drain cover. After the high-pressure gas is evenly dispersed, it is discharged from the bottom of the drain cover to form an air curtain and create a dry area.

[0017] S4: The underwater laser printing unit prints steel bars at a certain height at the damaged area. After printing, the underwater laser printing unit is adjusted to the next position for printing. The printing height is the same as above. After printing one layer, the underwater laser printing unit is adjusted back to the initial position.

[0018] S5: After the underwater laser printing unit completes the printing of the steel bar at one position, the underwater concrete printing unit starts working, adjusts to the corresponding position to print concrete, and the printing height of the concrete is slightly lower than the printing height of the steel bar. The underwater concrete printing unit works closely following the underwater laser printing unit.

[0019] S6: After completing the printing of one layer, the underwater laser printing unit adjusts its position to print the reinforcing bar of the next layer. Based on the existing reinforcing bar, it continues to print the reinforcing bar to increase its height. Subsequently, the underwater concrete printing unit works, and the height of the printed concrete is slightly lower than the height of the already printed reinforcing bar.

[0020] S7: After completing one layer of printing, the underwater laser printing unit and the concrete printing unit return to their initial positions, and then print the next layer according to the above steps, repeating the cycle until the printing work is completed.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0022] (1) This invention proposes an underwater steel bar and concrete composite printing device and method, which can directly repair underwater damaged buildings, avoiding the time cost loss caused by traditional demolition and reconstruction repair, and greatly reducing the economic cost of repair compared with traditional drainage repair.

[0023] (2) The present invention proposes an underwater steel bar and concrete composite printing device and method, which uses a drainage cover to create a dry environment underwater, avoiding the negative impact of water on the printing process, and effectively overcoming the problem that traditional concrete printing and laser printing cannot be carried out underwater.

[0024] (3) The present invention proposes an underwater steel bar and concrete composite printing device and method, which can print steel bars and concrete at the same time. Existing underwater repair mainly involves printing concrete at the damaged area. Compared with simply using concrete to repair damaged buildings, adding steel bars to the damaged area can significantly improve the strength of the repaired area.

[0025] (4) This invention proposes an underwater steel bar and concrete composite printing device and method, which uses a moving accessory storage bin, a guide rail moving unit, and a robotic arm to adjust the position of the printing nozzle, and can precisely control the nozzle to move to the repair position. Compared with the existing single guide rail moving unit or robotic arm device, the combination of the three methods has a higher degree of freedom and more accurate positioning. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0027] Figure 2 This is a schematic diagram of the accessory storage compartment structure of the present invention;

[0028] Figure 3 This is a schematic diagram of the guide rail moving unit structure of the present invention;

[0029] Figure 4 This is a schematic diagram of the robotic arm structure of the present invention;

[0030] Figure 5 This is a schematic diagram of the underwater concrete printing unit structure of the present invention;

[0031] Figure 6 This is a schematic diagram of the underwater laser printing unit structure of the present invention.

[0032] Reference numerals: 1. Accessory storage bin; 101. Guide rail bearing surface; 102. Gas thruster; 103. Concrete silo; 104. Rebar silo; 105. Battery; 106. Gas cylinder; 107. Control center; 2. Guide rail moving unit; 201. X-rail; 202. Y-rail; 203. Guide rail slider; 204. Circular turntable; 3. Robotic arm; 301. Robotic arm base; 302. Upper arm; 303. Lower arm; 304. End connector; 305. Rotary joint; 4. Underwater concrete printing unit; 401. Concrete nozzle; 4 02. Spiral stirring rod; 403. Lower connector of the first drainage cover; 404. Middle connector of the first drainage cover; 405. Upper connector of the first drainage cover; 406. First connecting screw; 407. First one-way valve; 408. First waterproof shell; 409. Motor compartment; 5. Underwater laser printing unit; 501. Laser print head; 502. Lower connector of the second drainage cover; 503. Middle connector of the second drainage cover; 504. Upper connector of the second drainage cover; 505. Second one-way valve; 506. Second waterproof shell; 507. Connector; 508. Second connecting screw. Detailed Implementation

[0033] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. These embodiments are implemented under the premise of the technical solution of the present invention. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0034] This embodiment of an underwater composite printing device for reinforcing steel and concrete includes a parts storage chamber 1, a guide rail moving unit 2, a robotic arm 3, an underwater concrete printing unit 4, and an underwater laser printing unit 5. The parts storage chamber 1 can float underwater at the repair location. The guide rail moving unit 2 is fixed to the surface of the parts storage chamber 1. The robotic arm base 301 is connected to a circular turntable 304 on the guide rail moving unit 1. The underwater concrete printing unit 4 consists of a drainage hood and a concrete printing device, with its end connected to the end connector 304 of the robotic arm. The underwater laser printing unit 5 consists of a drainage hood and a laser printing device, with its end connected to the end connector 304 of the robotic arm. The air curtain formed by the drainage hood creates a dry environment underwater, providing dry conditions for printing concrete and reinforcing steel.

[0035] In some embodiments, the accessory storage compartment guide rail bearing surface 101 provides a laying position for the guide rail moving unit 2; the accessory storage compartment is equipped with a gas thruster 102 for adjusting its position in water; the accessory storage compartment is equipped with a gas cylinder 106 capable of storing high-pressure gas required for the drainage hood to form an air curtain; the accessory storage compartment is equipped with a concrete hopper 103 capable of storing repair materials required for the underwater concrete printing unit; the accessory storage compartment is equipped with a steel bar hopper 104 capable of storing materials for printing steel bars required for the underwater laser printing unit; the accessory storage compartment is equipped with a battery 105 capable of providing power and other energy required for the device to operate; and the accessory storage compartment is equipped with a control center 107 capable of carrying communication and remote control devices.

[0036] In some embodiments, the guide rail moving unit 2 comprises an X-rail 201, a Y-rail 202, a guide rail slider 203, and a circular turntable 204. The X-rail 201 in the guide rail moving unit 1 is fixed to a specific bearing surface of the accessory storage compartment 1. The overall length of the X-rail 201 is longer than the bearing surface of the accessory storage compartment 1, providing greater X-direction adjustment. The Y-rail 202 in the guide rail moving unit 2 is mounted on the X-rail 201, enabling free movement in the X direction. The guide rail slider 203 in the guide rail moving unit 2 is mounted on the Y-rail 202, enabling free movement in the Y direction. The circular turntable 204 in the guide rail moving unit 2 is fixed to the guide rail slider 203. The circular turntable 203 can rotate 360°, and the robotic arm 3 fixed to the circular turntable 204 can achieve rotational adjustment. The guide rail moving unit 2 can provide precise adjustment for the robotic arm 3 in the X, Y, and circumferential directions.

[0037] In some embodiments, after the parts storage compartment 1 reaches the repair position, the guide rail moving unit 2 can adjust the underwater concrete printing unit 4 and the underwater laser printing unit 5 to a more precise position.

[0038] In some embodiments, the robotic arm 3 comprises a base 301, a large arm 302, a small arm 303, an end effector 304, and a rotary joint 305. The base 301 is fixed to a circular turntable 204, and the rotation of the turntable 204 causes the robotic arm 3 to adjust in the circumferential direction. The large arm 302 is connected to the base 301 via the rotary joint 305, the small arm 303 is connected to the large arm 302 via the rotary joint 305, and the small arm 303 is connected to the end effector 304 via the rotary joint 305. The end effector 304 is connected to the underwater concrete printing unit 4 and the underwater laser printing unit 5. The robotic arm 3 can precisely adjust the position of the underwater concrete printing unit 4 and the underwater laser printing unit 5.

[0039] In some embodiments, the underwater concrete printing unit 4 includes a concrete nozzle 401, a spiral stirring rod 402, a drainage cover 403-405, a connecting screw 406, a one-way valve 407, a waterproof cover 408, and a motor compartment 409.

[0040] In some embodiments, the drainage hoods 403-405 comprise a lower drain hood connector 403, a middle drain hood connector 404, and an upper drain hood connector 405, assembled together by connecting screws 406. The interior of the drainage hoods 403-405 consists of three drainage hood modules 403, 404, and 405, forming a tortuous gas circuit. This circuit evenly disperses the high-pressure gas from the first one-way valve 407, which is then ejected from the bottom of the first drainage hoods 403-405, forming a frustum-shaped air curtain at the bottom to create an underwater drying zone. The first one-way valve 407 is fitted at a pre-reserved interface on the drainage hood, providing one-way high-pressure gas. A spiral stirring rod 402 is fitted into a concrete nozzle 401, stirring the concrete in the nozzle and preventing it from hardening. The concrete nozzle 401 is fitted onto the drainage hoods 403-405 by the first connecting screws 406. The first waterproof cover 408 is assembled onto the first drainage cover 403-405 and the concrete nozzle 401, eliminating the gap between the first drainage cover 403-405 and the concrete nozzle 401 to prevent water seepage. The motor compartment 409 houses a motor that drives the spiral stirring rod 402 to rotate. The motor compartment 409 cooperates with the first waterproof cover 408 and the robotic arm end connector 304. The underwater concrete printing unit 4 enables concrete printing repair under underwater drying conditions.

[0041] In some embodiments, the underwater laser printing unit 5 consists of a laser printhead 501, a second drainage cover 502-504, a second one-way valve 505, a second waterproof cover 506, a connector 507, and a second connecting screw 508.

[0042] In some embodiments, the second drainage cover 502-504 includes a lower connector 502, a middle connector 503, and an upper connector 504. These three modules of the second drainage cover 502-504 are assembled in a top-middle-bottom order and fixed together by a second connecting screw 508, forming a tortuous gas circuit inside the drainage cover. High-pressure gas enters the drainage cover through a second one-way valve 505, is evenly dispersed in the gas circuit, and then ejects from the bottom of the second drainage cover 502-504, forming a frustum-shaped air curtain at the bottom of the second drainage cover 502-504, creating an underwater drying zone. The second one-way valve 505 is fitted at a pre-reserved interface in the second drainage cover 502-504 to provide one-way high-pressure gas. A laser printhead 501 is fitted inside the second waterproof cover 502-504 and has the function of printing steel bars underwater. A second waterproof cover 506 mates with the drainage cover 502-504 and the laser printhead 501 to eliminate gaps and prevent water leakage. The laser printhead 501 is equipped with a connector 507 at its end, which cooperates with the robotic arm end connector 304 to achieve position adjustment of the underwater laser printing unit 5. The laser printhead 5 can print steel bars under underwater drying conditions.

[0043] A method for underwater composite printing of steel bars and concrete based on the above embodiments includes the following steps:

[0044] S1: After the parts storage compartment 1 is submerged in water, it is adjusted to the repair area using a gas thruster.

[0045] S2: The guide rail moving unit 2 and the robotic arm 3 mounted on the accessory storage compartment 1 adjust the underwater laser printing unit 5 and the underwater concrete printing unit 4 to the corresponding damaged positions.

[0046] S3: High-pressure gas is introduced into the one-way valve and enters the gas circuit inside the drain cover. After the high-pressure gas is evenly dispersed, it is discharged from the bottom of the drain cover to form an air curtain and create a dry area.

[0047] S4: Underwater laser printing unit 4 is working, printing steel bars to repair the damaged area.

[0048] S5: The guide rail moving unit 2 and the robotic arm 3 adjust the concrete printing unit 5 to the position of the printed steel bar and perform concrete printing.

[0049] In some embodiments, the specific steps of composite printing in S4-5 are as follows:

[0050] Step 1: The underwater laser printing unit 4 prints steel bars at a certain height on the damaged area. After printing, the underwater laser printing unit 4 is adjusted to the next position for printing, with the same printing height. After completing one layer of printing, the underwater laser printing unit 4 is adjusted back to the initial position.

[0051] Step Two: After the underwater laser printing unit 4 completes the printing of the reinforcing steel at one location, the underwater concrete printing unit 5 begins operation, adjusting itself to the corresponding position for concrete printing. The printing height of the concrete is slightly lower than the height of the printed reinforcing steel. The underwater concrete printing unit 5 works immediately following the underwater laser printing unit 4.

[0052] Step 3: After completing the printing of one layer, the underwater laser printing unit 5 is adjusted to print the next layer of steel reinforcement. Based on the existing reinforcement, printing continues, increasing the height of the steel reinforcement. Subsequently, the underwater concrete printing unit 4 begins operation, printing concrete at a height slightly lower than the already printed reinforcement.

[0053] Step 4: After completing one layer of printing, the underwater laser printing unit 5 and the concrete printing unit 4 return to their initial positions, and then the next layer is printed according to the above steps. This cycle is repeated until the printing work is completed.

Claims

1. An underwater steel bar and concrete composite printing device, characterized in that, The system includes a parts storage compartment (1), a guide rail moving unit (2), a robotic arm (3), an underwater concrete printing unit (4), and an underwater laser printing unit (5). The parts storage compartment (1) is suspended underwater at the repair location. The guide rail moving unit (2) is fixed around the parts storage compartment (1). The base of the robotic arm (3) is connected to a circular turntable on the guide rail moving unit (2). The underwater concrete printing unit (4) includes a first drainage cover and a concrete nozzle (401). The end of the underwater concrete printing unit (4) is connected to the end of the robotic arm (3). The underwater laser printing unit (5) includes a second drainage cover and a laser printing nozzle (501). The end of the underwater laser printing unit (5) is connected to the robotic arm (3). The first drainage cover and / or the second drainage cover form an air curtain to create a dry environment underwater, providing dry conditions for printing concrete and steel bars. The accessory storage compartment (1) includes a guide rail bearing surface (101), a gas thruster (102), a concrete silo (103), a steel bar silo (104), a battery (105), a gas cylinder (106), and a control center (107); the guide rail bearing surface (101) is used to install the guide rail moving unit (2); the gas thruster (102) is used to drive the accessory storage compartment (1) to adjust its position in the water; the gas cylinder (106) stores the high-pressure gas required for the first drainage cover and / or the second drainage cover to form an air curtain; the concrete silo (103) stores the repair materials required for the underwater concrete printing unit; the steel bar silo (104) stores the materials required for printing steel bars for the underwater laser printing unit; the battery (105) provides power for the device to work; and the control center (107) carries communication and remote control devices. The guide rail moving unit (2) includes an X guide rail (201), a Y guide rail (202), a guide rail slider (203), and a circular turntable (204). The X guide rail (201) is fixed on the guide rail bearing surface (101), and the overall length of the X guide rail (201) is longer than that of the guide rail bearing surface (101). The Y guide rail (202) is mounted on the X guide rail (201) to achieve free movement in the X direction. The guide rail slider (203) is mounted on the Y guide rail (202) to achieve free movement in the Y direction. The circular turntable (204) is fixed on the guide rail slider (203), and the circular turntable (204) can rotate 360°. The robotic arm (3) is fixed on the circular turntable (204) to achieve rotation adjustment.

2. The underwater steel bar and concrete composite printing device according to claim 1, characterized in that, The robotic arm (3) includes a base (301), a large arm (302), a small arm (303), an end connector (304), and a rotary joint (305); the base (301) is fixed on the circular turntable (204); the large arm (302) is connected to the base (301) through the rotary joint (305), the small arm (303) is connected to the large arm (302) through the rotary joint (305), the small arm (303) is connected to the end connector (304) through the rotary joint (305), and the end connector (304) is connected to the underwater concrete printing unit (4) and the underwater laser printing unit (5).

3. The underwater steel bar and concrete composite printing device according to claim 2, characterized in that, The underwater concrete printing unit (4) includes a concrete nozzle (401), a spiral stirring rod (402), a first drainage cover, several first connecting screws (406), a first one-way valve (407), a first waterproof cover (408), and a motor compartment (409). The first drainage cover includes a lower connector (403), a middle connector (404), and an upper connector (405) connected together by the first connecting screws (406). The first drainage cover contains three drainage cover modules, forming a tortuous gas circuit. The high-pressure gas from the first one-way valve (407) is evenly dispersed in the circuit and sprayed out from the bottom of the first drainage cover, forming a frustum-shaped gas flow at the bottom of the first drainage cover. A curtain is used to create an underwater drying zone; the first one-way valve (407) is installed at the reserved interface of the first drainage cover to provide one-way high-pressure gas; the spiral stirring rod (402) is installed in the concrete nozzle (401), the concrete nozzle (401) is installed on the first drainage cover by the first connecting screw (406), and the first waterproof cover (408) is installed on the first drainage cover and the concrete nozzle (401); the motor chamber (409) is equipped with a motor to drive the spiral stirring rod (402) to rotate, and the motor chamber (409) cooperates with the first waterproof cover (408) and the end connector (304) of the robotic arm; the underwater concrete printing unit (4) is used to realize concrete printing repair under underwater drying conditions.

4. The underwater steel bar and concrete composite printing device according to claim 2, characterized in that, The underwater laser printing unit (5) includes a laser printhead (501), a second drainage cover, a second one-way valve (505), a second waterproof cover (506), a connector (507), and several second connecting screws (508). The second drainage cover is composed of a lower connector (502), a middle connector (503), and an upper connector (504). The three modules of the second drainage cover are assembled together in the order of top, middle, and bottom, and fixed together by the second connecting screws (508). A tortuous gas circuit is formed inside the second drainage cover. High-pressure gas enters the drainage cover through the second one-way valve (505), is evenly dispersed in the gas circuit, and then flows out from the bottom of the second drainage cover. The gas is ejected from the second drainage cover and forms a frustum-shaped air curtain at the bottom of the second drainage cover, creating an underwater drying zone; the second one-way valve (505) is installed at the reserved interface of the second drainage cover to provide one-way high-pressure gas; the laser print head (501) is installed inside the second waterproof cover and has the function of printing steel bars underwater; the second waterproof cover (506) is connected to the second drainage cover and the laser print head (501); the laser print head (501) is equipped with the connector (507) at the end and cooperates with the end connector (304) of the robotic arm to realize the position adjustment of the underwater laser printing unit (5); the laser print head (501) can realize the printing of steel bars under underwater drying conditions.

5. A method for underwater composite printing of reinforcing steel bars and concrete, characterized in that, Using the underwater steel bar and concrete composite printing device as described in any one of claims 1-4, the underwater concrete printing unit (4) and the underwater laser printing unit (5) alternately perform layered printing repair of the steel bar structure and concrete structure of the underwater damaged building structure; after the accessory storage bin (1) is put into the water, it is adjusted to the repair area by the gas propulsion unit (102), and the underwater laser printing unit (5) is adjusted to the corresponding damaged position by the guide rail moving unit (2) and the robotic arm (3) to print the steel bar; after the steel bar printing is completed, the underwater concrete printing unit (4) is adjusted to the position of the steel bar by the guide rail moving unit (2) and the robotic arm (3) to perform concrete printing repair; the underwater concrete printing unit (4) works closely following the underwater laser printing unit (5).

6. The underwater steel reinforcement and concrete composite printing method according to claim 5, comprising the following steps: S1: After the accessory storage compartment is submerged in water, it is adjusted to the repair area using a gas thruster; S2: The guide rail moving unit and the robotic arm mounted on the accessory storage compartment adjust the underwater laser printing unit and the underwater concrete printing unit to the corresponding damage position; S3: The one-way valve inputs high-pressure gas, which enters the gas circuit inside the drain cover. After the high-pressure gas is evenly dispersed, it is discharged from the bottom of the drain cover to form an air curtain and create a dry area. S4: The underwater laser printing unit prints steel bars at a certain height at the damaged area. After printing, the underwater laser printing device is adjusted to the next position for printing. The printing height is the same as above. After printing one layer, the underwater laser printing unit is adjusted back to the initial position. S5: After the underwater laser printing unit completes the printing of the steel bar at one position, the underwater concrete printing unit starts working, adjusts to the corresponding position to print concrete, and the printing height of the concrete is slightly lower than the printing height of the steel bar. The underwater concrete printing unit works closely following the underwater laser printing unit. S6: After completing the printing of one layer, the underwater laser printing unit adjusts its position to print the reinforcing bar of the next layer. Based on the existing reinforcing bar, it continues to print the reinforcing bar to increase its height. Subsequently, the underwater concrete printing unit works, and the height of the printed concrete is slightly lower than the height of the already printed reinforcing bar. S7: After completing one layer of printing, the underwater laser printing unit and the underwater concrete printing unit return to their initial positions, and then print the next layer according to the above steps, repeating the cycle until the printing work is completed.

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