Local dry type underwater TIG (Tungsten Inert Gas) welding system and welding method

Abstract

The invention discloses an underwater local dry TIG welding repair system and a welding method. The welding repair system is characterized by comprising a robot, a TIG welding power supply, a TIG welding gun, water cooling equipment, a wire feeding device, a movable contact drainage cover, shielding gas equipment, drainage gas equipment, intelligent monitoring equipment, an ultrasonic frequency pulse power supply device, an electric signal detection device and an acoustic signal detection device. The four systems are connected with an industrial robot, and the underwater local dry method TIG welding system is jointly formed. Defect positions can be accurately captured through the visual sensing system, the welding process can be adjusted through real-time images fed back by intelligent monitoring equipment, underwater refined welding work is achieved, and the welding quality is further improved by applying ultrasonic frequency pulses to assist the welding system. By adopting the underwater repair system, the underwater repair work of equipment such as the spent fuel pool can be better completed in a complex environment in the nuclear power field, and the application is wide.

Description

Technical Field

[0001] The invention belongs to the technical field of underwater welding, and relates to a novel local dry TIG welding technology for underwater environment, in particular to a local dry underwater TIG welding system and a welding method. Background Art

[0002] With the continuous improvement of nuclear energy utilization, the output of spent fuel is also increasing. Usually, the spent fuel is stored in the spent fuel pool by wet storage. The cover plate of the spent fuel pool has been in service for a long time under high temperature, radiation, boric acid corrosion and other environments, and is prone to stress corrosion, cracks and other defects. The deepening of defects will further cause leakage of the spent fuel pool, and then cause nuclear accidents. Therefore, the underwater repair of the spent fuel pool has become more and more important. Due to the poor visibility and radiation in the repair environment of the spent fuel pool, if manual welding is used for repair, it will be detrimental to the health of the divers. Therefore, it is imperative to use an underwater automated repair system equipped with an industrial robot to repair the spent fuel pool.

[0003] Compared with conventional underwater wet welding repair technology, the arc of underwater local dry welding technology is more stable, but due to the rapid cooling effect of water, it will still cause defects such as pores and cracks to form on the weld metal. Therefore, new underwater welding methods are needed to reduce the formation of defects.

[0004] Among the existing technologies, Patent 202211661297.7 introduces a TIG welding torch for underwater tube sheet structure welding and its use method, which is characterized in that the tungsten electrode is fixed on the copper base, and the copper base is connected to the conductive rotating body by a thread. The motor drives the conductive rotating body to move in a circle around a fixed diameter to achieve TIG welding of the tube sheet structure, and a rubber ring is used for sealing. However, this equipment is only suitable for welding annular welds, and the drainage cover cannot be moved for welding. At the same time, the drainage cover is not equipped with wire feeding equipment, and TIG wire filling welding cannot be performed. Patent 202210174295.9 introduces a micro-area strong drainage tungsten electrode TIG welding torch for underwater local dry operations. The welding torch is characterized by a simple and compact structure and low cost. It can meet the welding needs in a narrow welding space. At the same time, the welding torch can increase the number of tungsten electrodes by adding a tungsten electrode fixing sleeve to achieve multi-tungsten electrode underwater welding. Patent 202211026007.1 introduces an underwater welding device for welding upper core plate locating pins and nuts. The equipment adopts a double tungsten electrode TIG welding method, which is mainly used for welding and repairing locating pins and nuts in nuclear reactor cores. However, the above two types of equipment are only suitable for spot welding of locating pins, etc. in the nuclear power field, and are not suitable for long-distance TIG wire welding. At the same time, the above two drainage devices are not equipped with intelligent monitoring equipment, and the drainage status and welding status of the device cannot be monitored. Patent 202111270086.6 introduces a method for ultrasonic frequency pulse assisted arc welding of dissimilar steels in an underwater wet environment. This method couples the ultrasonic frequency pulse electrical signal with the welding power supply electrical signal to stimulate a good ultrasonic arc, thereby assisting underwater wet MIG welding and achieving high-quality welding of dissimilar steels underwater. However, there is little research on the introduction of ultrasonic frequency arc as an auxiliary means in the local dry TIG wire welding process. Summary of the invention

[0005] The purpose of the present invention is to invent a local dry underwater TIG welding system and welding method in view of the shortcomings of the prior art and the defects in the welding repair process. Its integrated fully automatic welding system can monitor the welding process in real time and finely adjust the repair process; the introduction of ultrasonic frequency pulse arc auxiliary means can reduce the content of diffused hydrogen, reduce defects such as pores and cracks, and further improve the welding quality.

[0006] One of the technical solutions of the present invention is: A local dry underwater TIG welding system, characterized in that it consists of a TIG welding system, an underwater welding drainage system, an ultrasonic frequency pulse auxiliary system, an industrial robot and a visual sensing system. The TIG welding system consists of a TIG welding power supply, a TIG welding gun water cooling equipment, a TIG welding gun and a shielding gas equipment. The underwater welding drainage system consists of a drainage cover, a drainage gas equipment, an intelligent monitoring equipment and a wire feeding equipment. The ultrasonic frequency pulse auxiliary system consists of an ultrasonic frequency pulse power supply, an electrical signal detection equipment and an acoustic signal detection equipment. The TIG welding power supply, the TIG welding gun water cooling equipment and the shielding gas equipment are connected to the TIG welding gun. The TIG welding gun is assembled on the industrial On the robot arm; the TIG welding gun head is assembled inside the drainage hood through a threaded connection, and the wire feeding equipment, intelligent monitoring equipment and drainage gas equipment are connected to the drainage hood through a mechanical connection; the lens of the intelligent monitoring equipment is located inside the drainage hood to detect the welding process in real time; the visual sensing system is connected to the industrial robot arm and is responsible for capturing and identifying defects; the drainage gas equipment is connected to the inner cavity of the drainage hood to achieve drainage; the ultrasonic frequency pulse power supply is coupled to the TIG welding power supply through an isolation coupling device, and the electrical signal detection equipment and the sound signal detection equipment respectively monitor the current and voltage of the welding process and the sound signal generated during the welding process.

[0007] The intelligent monitoring equipment is integrated on the local dry drainage cover, which can obtain real-time images of the welding area in the drainage cover. During the nuclear power repair process, the real-time images fed back by the intelligent monitoring equipment can be used to further optimize the repair path, realize the refined repair of the defective area, and further improve the quality of the weld. The visual sensing equipment is connected to the industrial robot to capture and identify existing defects.

[0008] In order to facilitate underwater welding repair, the wire feeding equipment is also integrated into the drainage cover, so that the wire feeding equipment does not need to be assembled separately. After the wire feeding equipment is integrated with the drainage cover, the welding wire and the tungsten electrode center of the TIG welding gun are in the same plane, ensuring the uniformity and quality of the weld during the welding process.

[0009] The connection between the drain hood and the TIG welding gun adopts a threaded connection. This connection method ensures the airtightness inside the drain hood and the stability of the TIG welding gun's movement during welding, so that the welding gun is always located in the center of the drain hood.

[0010] The ultrasonic frequency pulse auxiliary system can couple a good square wave and stimulate an ultrasonic arc on the arc formed by the TIG welding power source, thereby introducing ultrasonic energy into the welding pool and improving the welding quality. The electrical signal detection equipment measures the electrical signal characteristics of the coupling loop, and the acoustic signal detection equipment measures the arc ultrasonic signal characteristics during the welding process, which can realize the evaluation of arc stability.

[0011] The second technical solution of the present invention is: A welding method based on the local dry underwater TIG welding system is characterized by: Step 1: On the workpiece to be welded, according to the defect size, use the electric spark method or machining method to remove the defect, and process the welding area into a V / U / trapezoidal groove with the groove size of length × width × height 200 × 15 × 10mm, and the groove angle is not more than 80°; Step 2: Use the operation panel of the industrial robot to complete the programming of the underwater welding motion trajectory, and set the welding speed required for welding through the control panel; set the current parameters required for welding through the TIG welding power supply; set the wire feeding speed required for welding through the wire feeding equipment; the welding parameters are set as follows: welding current: 100-350A, welding speed: 100mm / min-500mm / min, wire feeding speed: 80-700cm / min, ultrasonic frequency pulse power supply excitation voltage: 50V-110V, excitation frequency: 50kHz-90kHz; Step 3: Start the TIG welding system and ultrasonic pulse auxiliary system, turn on the protective gas equipment and drainage gas equipment, operate the industrial robot to put the drainage welding system into water, turn on the intelligent monitoring equipment to monitor the welding process, and when it is detected that the water in the welding area is completely drained, start the arc and wire feeding and start the motion program; after the welding experiment is completed, stop the wire feeding and extinguish the arc, and turn off the above equipment in turn.

[0012] Step 4: After welding is completed, take out the local dry underwater TIG welding system, grind the welded workpiece, and perform non-destructive testing and mechanical property testing on the welded workpiece.

[0013] The TIG welding power source is a high-frequency arc starter placed underwater through a waterproof design to reduce arc starting difficulties caused by excessively long cables, and the no-load voltage is 100V.

[0014] The advantages and beneficial effects of the present invention are: 1. The underwater local dry TIG welding system integrates the TIG welding gun, drainage equipment, intelligent monitoring equipment, and wire feeding equipment on the drainage cover, and uses an industrial robot to control the movement of the drainage cover, realizing the full automation of the underwater welding repair process. The visual sensing equipment can capture and identify defects, and the intelligent monitoring equipment can detect the drainage process and the welding repair process in real time, so that a better repair path can be designed during the repair process, and the repair process can be adjusted more subtly and effectively. The visual sensing equipment is connected to the industrial robot, which can capture and identify existing defects, making defect repair more accurate.

[0015] 2. The drainage cover of the present invention has a simple and compact structure and is suitable for repair work in complex and restricted environments. The sealing layer of the drainage cover is composited with high-temperature resistant cloth and carbon fiber layer, which can better ensure a water-free environment in the welding area and further improve the service life of the sealing layer.

[0016] 3. High-frequency (frequency>20kHz) pulsed arc has the advantages of "high-frequency contraction effect" and "arc ultrasonic effect". When the electromagnetic effect and ultrasonic effect act on the molten pool, strong electromagnetic stirring and ultrasonic vibration can be generated, which can stabilize the arc, reduce defects and refine grains. The use of ultrasonic arc to assist underwater local dry TIG welding can stabilize the welding arc and reduce the diffused hydrogen content and defects such as pores and cracks in the repaired weld.

[0017] 4. The present invention is applicable to different types of V / U / trapezoidal grooves, and the applicable groove size is not greater than length×width×height 200×15×10mm.

[0018] 5. The present invention can accurately capture the defect position through the visual sensing system, and can also adjust the welding process through the real-time image feedback from the intelligent monitoring equipment, realize the underwater refined welding work, and use the ultrasonic frequency pulse auxiliary system to assist the welding process to further improve the weld quality. The underwater repair system can better complete the underwater repair work of equipment such as spent fuel pools in the complex environment of the nuclear power field; at the same time, the underwater repair system can also complete the repair work of marine engineering equipment such as marine oil and gas pipelines and ships in the marine environment, and obtain high-quality welding repair layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the structural diagram of the underwater local dry TIG welding system.

[0020] Figure 2 Schematic diagram of the underwater local dry TIG welding drainage cover used in the present invention, wherein (a) is the main view and (b) is the left view.

[0021] Figure 3 This is a cross-sectional view of the underwater local dry TIG welding drainage shield used in the present invention.

[0022] Figure 4 This is the macroscopic morphology of the underwater local dry TIG welding repair layer.

[0023] Figure 5 This is the cross-sectional morphology of the underwater local dry TIG welding repair layer.

[0024] In the figure: 1 is a TIG welding gun, 2 is a connecting thread, 3 is a welding drainage cover, 4 is a drainage gas inlet hole, 5 is a wire feeding tube, 6 is a wire feeding tube connection port, 7 is a welding tungsten electrode, 8 is a welding workpiece, 9 is a welding wire, 10 is an intelligent monitoring device, 11 is a drainage gas inlet hole, 12 is a welding seam, 13 is a sealing layer, 14 is a carbon fiber, and 15 is a high temperature resistant metal cloth. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. Example

[0026] like Figure 1-2 shown.

[0027] A local dry underwater TIG welding system, such as Figure 1 As shown in the figure, this system consists of an industrial robot, a TIG welding power supply, a TIG welding gun water cooling equipment, a TIG welding gun, an underwater local dry welding drainage cover, a protective gas and drainage gas equipment, an intelligent camera, a wire feeding equipment, an ultrasonic frequency pulse power supply, an electrical signal detection equipment, and an acoustic signal detection equipment. The welding power supply is connected to the TIG welding gun, the water cooling equipment, and the protective gas equipment to form a TIG welding system; the intelligent monitoring equipment is integrated with the wire feeding equipment and the drainage gas equipment on the drainage cover to form an underwater welding drainage system; the ultrasonic frequency pulse power supply is coupled with the welding power supply through an isolation coupling device and connected with the electrical signal detection equipment and the acoustic signal detection equipment to form an ultrasonic frequency pulse auxiliary system; the visual sensing system is connected to the industrial robot to obtain the surrounding environment image and is responsible for capturing and identifying the defects of the workpiece to be repaired. The four systems, namely the TIG welding system, the underwater welding drainage system, the ultrasonic frequency pulse auxiliary system, and the visual sensing system, are connected to the industrial robot to form an underwater local dry TIG welding system.

[0028] The industrial robot includes a control cabinet and a mechanical arm. The mechanical arm is connected to the welding gun 1 by a mechanical connection. By programming the welding repair path and the welding speed, the industrial robot can drive the drainage cover 3 to perform precise underwater repair along the set path.

[0029] In the TIG welding system, the welding power supply is connected to the welding gun cable to provide the necessary arc for the welding process and can adjust the welding current parameters; the water cooling equipment is connected to the water inlet of the welding gun and the water outlet of the welding power supply to form a closed circulating water circuit to effectively dissipate the heat of the TIG welding gun; argon gas is used as the shielding gas, and the gas cylinder is connected to the welding power supply. The shielding gas equipment can protect the welding process and also play a role in drainage.

[0030] In the ultrasonic pulse auxiliary system, the ultrasonic pulse power supply electrical signal and the TIG welding power supply electrical signal are coupled through an isolation coupling device, which can couple a good square wave and stimulate an ultrasonic arc, thereby transmitting ultrasonic energy to the welding pool and further improving the welding quality. The electrical signal acquisition system consists of a Hall current sensor, a Hall voltage sensor and a NI data acquisition card. The sensor is responsible for collecting signals, and the NI data acquisition card converts the collected signals into digital signals and transmits them to the PC. The acoustic signal acquisition system consists of an underwater acoustic signal sensor and a data acquisition card. The sensor can convert underwater acoustic signals into electrical signals and transmit them to the PC through the data acquisition card for analysis.

[0031] Underwater welding drainage system Figure 2 As shown, in order to facilitate nuclear power maintenance, the drainage hood adopts a small-size design. The TIG welding gun 1 is connected to the drainage hood 3 by means of a threaded connection 2. 4 and 11 are the air inlets for the drainage gas. The air inlets adopt channel-type air supply, and an annular transition is adopted at the turning point. The wire feeding tube 5 in the wire feeding equipment is connected to the drainage hood through the wire feeding tube connection port 6 provided by the drainage hood. The welding wire 9 in the wire feeding tube is closely matched with the welding tungsten electrode 7 to ensure the welding quality. The intelligent monitoring equipment 9 is connected to the drainage hood through the monitoring equipment connection hole to detect the drainage process and the welding process in real time. A sealing layer is used to seal the drainage hood under the drainage hood, such as Figure 3 A high temperature resistant cloth 14 is compounded under the sealing layer to reduce the burning of the isolation layer during the welding process; a carbon fiber layer 15 is compounded inside the sealing layer to increase the strength of the inside of the isolation layer during the welding process.

[0032] The visual sensing system mainly includes a panoramic camera. The visual sensing system is connected to the industrial robot and can obtain images of the surrounding environment. It is responsible for capturing and identifying defects in the workpiece to be repaired. Example

[0033] like Figure 3-4 Shown This embodiment is an underwater local dry TIG welding method. The base material used is a 304 stainless steel plate with a thickness of 8 mm, and the welding wire used is an ER308L welding wire with a diameter of 1.2 mm. The welding method mainly includes the following steps: Step (1) Preparation before welding: Grind the 304 steel plate to be welded to remove surface impurities, open a V-shaped groove at the center of the steel plate, and grind the groove. The welding material is ER308L welding wire.

[0034] Step (2) sets the precise welding path and optimal welding parameters for underwater repair. The welding parameters are set as follows: Current (A) Welding speed (mm / min) Wire feeding speed (cm / min) Excitation voltage (V) Excitation frequency (kHz) Base welding 130 150 140 70 60 2nd pass weld 130 150 140 70 60 Welds 3-5 160 150 140 70 60 Turn on the protective gas equipment and the drainage gas equipment, operate the industrial robot to enter the water, wait for the water in the drainage cover to be drained, start the arc, feed the wire and move the robot, and conduct the underwater welding repair experiment along the set repair path.

[0035] The macroscopic morphology of the underwater local dry TIG welding repair layer after welding repair is completed is as follows Figure 4 As shown, the cross-sectional morphology of the welding repair layer is as follows Figure 5 shown. Example

[0036] The welding base material and filler wire of this embodiment are the same as those of the second embodiment, except that the welding parameters are changed and the groove angle is selected to be 45°. The welding parameters of this embodiment are: Current (A) Welding speed (mm / min) Wire feeding speed (cm / min) Excitation voltage (V) Excitation frequency (kHz) Base welding 100 100 80 110 90 Welds 2-4 120 100 80 110 90 Macroscopic morphology of the repair layer of underwater local dry TIG welding after welding repair Figure 4 Similarly, the cross-sectional morphology of the weld repair layer is Figure 5 similar. Example

[0037] The welding base material and filler wire of this embodiment are the same as those of the second embodiment, except that the welding parameters are changed and the groove angle is selected to be 70°. The welding parameters of this embodiment are: Current (A) Welding speed (mm / min) Wire feeding speed (cm / min) Excitation voltage (V) Excitation frequency (kHz) Base welding 200 300 300 50 50 Welds 2-5 250 300 300 50 50 Macroscopic morphology of the repair layer of underwater local dry TIG welding after welding repair Figure 4 Similarly, the cross-sectional morphology of the weld repair layer is Figure 5 similar.

[0038] The examples given above are only used to illustrate the present application. The present invention is not limited to the above examples. Non-essential changes, modifications, substitutions, and combinations made by those skilled in the art based on the technical features of the present invention are all included in the protection scope of the present invention.

[0039] Parts not involved in the present invention, such as coupling circuits, video acquisition and processing, signal transmission, etc., are the same as the prior art or can be implemented using the prior art.

Claims

1. A local dry underwater TIG welding system, characterized by: It consists of a TIG welding system, an underwater welding drainage system, an ultrasonic frequency pulse auxiliary system, an industrial robot and a visual sensing system. The TIG welding system consists of a TIG welding power supply, a TIG welding gun water cooling equipment, a TIG welding gun and a protective gas equipment. The underwater welding drainage system consists of a drainage cover, a drainage gas equipment, an intelligent monitoring equipment and a wire feeding equipment. The ultrasonic frequency pulse auxiliary system consists of an ultrasonic frequency pulse power supply, an electrical signal detection equipment and an acoustic signal detection equipment. The TIG welding power supply, the TIG welding gun water cooling equipment and the protective gas equipment are connected to the TIG welding gun, and the TIG welding gun is mounted on the mechanical arm of the industrial robot. The IG welding gun head is assembled inside the drain hood through a threaded connection, and the wire feeding equipment, intelligent monitoring equipment and drain gas equipment are connected to the drain hood through mechanical connection; the lens of the intelligent monitoring equipment is located inside the drain hood to detect the welding process in real time; the visual sensing system is connected to the industrial robot arm and is responsible for capturing and identifying defects; the drain gas equipment is connected to the inner cavity of the drain hood to achieve drainage; the ultrasonic frequency pulse power supply is coupled to the TIG welding power supply through an isolation coupling device, and the electrical signal detection equipment and the sound signal detection equipment respectively monitor the current and voltage of the welding process and the sound signal generated during the welding process.

2. The local dry underwater TIG welding system according to claim 1 is characterized in that: The threaded hole on the drainage cover for assembling the welding gun is located in the center of the drainage cover, and the extension line of the guide hole for assembling the wire feeding equipment must pass through the center of the drainage cover to ensure that the tungsten electrode and the welding wire are on the same plane during welding; at the same time, the angle between the guide hole and the horizontal plane is set to 10°-30°; during the assembly of the monitoring equipment, it is necessary to ensure that the extension line of the lens passes through the welding area, so that the underwater welding process can be detected in real time.

3. The local dry underwater TIG welding system according to claim 1 is characterized by: A sealing layer is provided under the drainage cover, and the sealing layer contacts the workpiece for sealing; a high-temperature resistant metal cloth is compounded under the sealing layer to reduce the burning of the isolation layer during the welding movement; a carbon fiber layer is compounded on the inner side of the sealing layer to reduce the adverse effects of the arc, molten pool and spatter on the sealing material during the welding process.

4. The local dry underwater TIG welding system according to claim 1 is characterized in that: The electrical signals of the ultrasonic frequency pulse power supply and the TIG welding power supply can couple out a square wave and stimulate an ultrasonic arc after passing through an isolation coupling device. The ultrasonic frequency pulse power supply can adjust the ultrasonic excitation voltage and excitation frequency. With the help of the cavitation and acoustic streaming effects generated by the ultrasonic arc in the molten pool, the molten pool can be stirred and the fluidity of the molten pool can be enhanced, thereby reducing the grain size of the weld, reducing pores, reducing the diffusible hydrogen content, and improving the performance of the weld.

5. A welding method based on the local dry underwater TIG welding system according to claim 1, characterized in that it The following steps are involved: Step 1: On the workpiece to be welded, according to the defect size, the defects are machined away by electric spark method or machining method, and the welding area is machined into a V / U / trapezoidal groove with the groove size of length × width × height 200 × 15 × 10 mm, and the groove angle is not greater than 80°; Step 2: Use the operation panel of the industrial robot to complete the programming of the underwater welding motion trajectory, and set the welding speed required for welding through the control panel; set the current parameters required for welding through the TIG welding power supply; set the wire feeding speed required for welding through the wire feeding equipment; the welding parameters are set as follows: welding current: 100-350A, welding speed: 100mm / min-500mm / min, wire feeding speed: 80-700cm / min, ultrasonic frequency pulse power supply excitation voltage: 50V-110V, excitation frequency: 50kHz-90kHz; Step 3: Start the TIG welding system and ultrasonic frequency pulse auxiliary system, turn on the protective gas equipment and drainage gas equipment, operate the industrial robot to make the drainage welding system enter the water, turn on the intelligent monitoring equipment to monitor the welding process, and when it is detected that the water in the welding area is completely drained, start the arc and wire feeding to start the motion program; After the welding experiment is completed, stop feeding the wire and extinguish the arc, and shut down the above equipment in sequence; Step 4: After welding is completed, the welded workpiece is polished and subjected to non-destructive testing and mechanical property testing.

6. The method according to claim 1, characterized in that: The TIG welding power source is a high-frequency arc starter placed underwater through a waterproof design to reduce arc starting difficulties caused by excessively long cables, and the no-load voltage is 100V.

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