Metal pipeline laser melting forging in-situ repair gas protection cover and using method

Abstract

The invention belongs to the technical field of metal pipeline in-situ repair, and particularly relates to a metal pipeline laser fusion forging in-situ repair gas protection cover and a using method, the metal pipeline laser fusion forging in-situ repair gas protection cover comprises a protection cover shell, a flexible protection cover, a flexible gas storage device, an oxygen content sensor and a supporting and fixing device; openings are formed in the top and the bottom of the protective cover shell, the bottom profile is matched with the outer surface of the metal pipeline, and an air inlet and an air outlet are formed in the side wall in the diagonal direction. The flexible shield is arranged at the top of the shell, is in sealed connection with the shell and is communicated with a working head of the laser cladding equipment; the flexible gas storage device comprises a gas storage ball, a connector, a valve plate and a valve rod and is used for buffering or supplementing gas. The oxygen content sensor is arranged in the shell, is connected with an external control system and is used for detecting the oxygen concentration in real time; the supporting and fixing device is arranged on the side portion of the shell. The problems that gas protection efficiency is low, sealing performance is poor and gas pressure cannot be adjusted in real time in the laser smelting forging repairing process are solved, and the efficiency, stability and adaptability of gas protection are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal pipeline repair, and in particular relates to a metal pipeline laser melting in-situ repair gas protection cover and a use method thereof. Background Art

[0002] In the gas, petroleum, and chemical industries, large metal pipelines are prone to cracks, corrosion, and other defects due to long-term exposure to extreme working conditions such as high temperature, high pressure, and corrosive media. If not repaired in a timely manner, it may cause gas leaks or pipeline ruptures, leading to serious safety accidents. Since pipelines are generally non-removable and the repair environment is complex, currently, commonly used metal pipeline repair methods include welding, mechanical repair, and bonding repair. However, these methods often have the following shortcomings: 1. Welding repairs may cause secondary damage to the pipeline material, affecting its structural integrity; 2. Mechanical repairs are difficult to perform fine repairs and cannot meet the needs of high-precision repairs; 3. Bonding repairs have poor durability and are prone to failure in high-temperature and high-pressure environments.

[0003] In contrast, laser melting and forging in-situ repair technology, due to the melting effect of its high-energy laser beam, can repair defects and strengthen the material surface through molten pool solidification and recrystallization, and has become an important means of in-situ repair of metal pipelines. Its basic principle is to use a high-energy laser beam to melt a cladding material with specific properties and deposit it on the surface of the base material to form an alloy cladding layer, thereby improving the material's wear resistance, corrosion resistance and high temperature resistance. In recent years, with the advancement of laser technology, the energy density, stability and controllability of laser beams have continued to improve, providing more reliable support for the development of this technology. At present, this technology has been widely used in aerospace, automobile manufacturing, mold repair and energy pipelines.

[0004] Laboratory-grade inert gas protection devices are bulky (such as large sealed boxes and multi-pipeline gas circulation systems) and cannot meet the needs of rapid repairs in the field. Field operations require the use of portable equipment, which may lack stable power supplies and require generators or batteries. The inert gas shield and repair equipment need to operate with low power consumption, so the designed structure is simple and reliable. Laser melting and forging has the advantages of small thermal impact on the pipeline, low deformation risk and high repair quality for inert gas protection. Inert gas shields can improve the quality of in-situ repairs by laser melting and forging. For this purpose, the inert gas shield designed is simple, practical and reliable in structure.

[0005] However, during the laser melting process, the high-temperature molten pool easily reacts chemically with elements such as oxygen, nitrogen, and hydrogen in the air, resulting in defects such as oxidation and pores in the cladding layer, which affects the quality of the repair. Therefore, an efficient gas protection device is crucial to isolate oxygen, reduce oxidation, and improve the density and mechanical properties of the cladding layer. Currently, some technical solutions have been attempted to solve the oxidation problem. For example:

[0006] Patent No. CN202123411456.1 discloses a flexible gas protection device for laser cladding equipment. The device adopts a metal frame and a foldable telescopic structure, and is equipped with a powder recovery tray and a quick connection interface for connecting powder gas, cooling water circuit, and negative pressure circuit, which realizes the rapid installation and fixation of the laser cladding head. However, this technical solution has the following problems: 1. The pressure regulation method relies on the negative pressure quick connector + inflation quick connector to control the gas flow, and forms a closed area through negative pressure exhaust to reduce oxygen infiltration. It is a passive pressure regulation and has no real-time feedback capability. It only relies on the negative pressure system to maintain a low oxygen environment. It cannot actively adjust the pressure and cannot dynamically adjust the air pressure under different cladding states. 2. It is mainly suitable for small-scale laser cladding and lacks systematic airflow control. 3. The sealing method of the device relies only on the magnetic connection frame + quick clamping assembly, which cannot effectively adapt to the curved surface structure and has relatively weak sealing.

[0007] Patent No. 202310059805.2 discloses an argon protective drag hood for welding, which adjusts the argon gas flow rate by rotating the dispersion screen to achieve the regulation of the argon gas flow. However, this technical solution has the following problems: 1. The drag hood design is mainly used for weld protection and cannot effectively cover the high-temperature melting and forging area of the metal pipe. 2. The argon flow rate is adjusted by the dispersion screen + angle adjustment mechanism to optimize the airflow distribution, which is a passive pressure regulation. When the drag hood moves during the welding process, it only relies on argon flow optimization, and the air pressure fluctuation cannot be automatically adjusted. It can only be alleviated by adjusting the screen or the gas supply rate. 3. It only has soft sealing materials and cannot work stably under high-pressure environments. 4. The argon flow structure reduces oxygen infiltration, but it cannot actively sense air pressure changes and relies on manual adjustment.

[0008] In summary, inert gas shields play a crucial role in the laser melting repair process. Their structural design and gas flow characteristics directly impact the final quality of the melted layer. However, existing gas shields still rely primarily on empirical design and lack a systematic optimization method, failing to meet the demand for efficient laser melting repair of metal pipelines. Therefore, there is an urgent need to develop an efficient and stable laser melting shield to improve repair quality and processing accuracy. Summary of the Invention

[0009] In response to the problems of insufficient protection, delayed air pressure regulation and poor sealing adaptability in the existing metal pipeline laser melting and forging repair process, the present invention provides a gas protection cover and usage method for in-situ repair of metal pipeline laser melting and forging, which effectively achieves efficient sealing, dynamic atmosphere control and improved repair quality.

[0010] In one aspect, the present invention provides a gas shield for in-situ repair of metal pipes during laser melting and forging. The shield shell has openings at its top and bottom, forming a repair space therein. The bottom profile of the shield shell matches the outer surface of the metal pipe to achieve sealed coverage. The side walls of the shield shell are provided with an air inlet and an air outlet, which are arranged along the diagonal direction of the overall structure of the shield shell and are used to input and exhaust protective gas.

[0011] A flexible shield is provided on the top of the protective shield shell and is circumferentially sealed along its edge; an interface is provided on the top of the flexible shield for communicating with the working head of the laser cladding equipment to form a closed laser repair space;

[0012] A flexible gas storage device is provided on the side of the protective cover shell, and includes a gas storage ball, a gas storage ball interface, a valve plate, and a valve stem; one end of the gas storage ball interface is connected to the gas storage ball, and the other end is passed through and connected to the side wall of the protective cover shell to achieve gas communication with the internal space thereof; the valve plate is provided inside the gas storage ball interface, one end of the valve stem is connected to the valve plate, and the other end extends out of the gas storage ball protective shell, and the valve stem is rotated to control the opening and closing state of the valve plate in the gas storage ball interface;

[0013] The gas storage ball is made of a flexible material with expandable properties and is used to automatically absorb part of the gas to buffer the pressure when the internal pressure of the protective cover shell increases, or release the stored gas to replenish the gas volume when the internal pressure decreases;

[0014] An oxygen content sensor is disposed inside the protective cover shell and connected to an external control system, and is used to detect the oxygen concentration in the protective cover shell in real time. When the detected oxygen content is higher than a set threshold, the air inlet and the air outlet are linked to open to replace the gas in the protective cover shell;

[0015] The supporting and fixing device is arranged on the side of the protective cover shell.

[0016] In a preferred implementation, further, the flexible gas storage device also includes an aluminum alloy mesh; the aluminum alloy mesh is arranged inside the gas storage ball interface.

[0017] In a preferred implementation, further, the internal space of the protective cover shell is divided into a melting and forging area, a processing area and a gas control area; the melting and forging area is located below the working head of the laser cladding equipment; the processing area is located outside the melting and forging area; the gas control area is located on the side of the protective cover shell, for installing the flexible gas storage device.

[0018] In a preferred implementation, further, it also includes a pressure sensor and a temperature sensor, which are arranged inside the protective cover shell and are used to monitor internal temperature and pressure parameters in real time.

[0019] In a preferred implementation, further, two mounting interfaces are provided on the top of the flexible shield, which are used to mount a laser cladding head and a laser impact head respectively.

[0020] In a preferred implementation, further, the supporting and fixing device includes an electromagnet and a steel wire rope, one end of the steel wire rope is hingedly connected to the protective cover shell, and the other end is installed with the electromagnet, which is used to detachably fix the protective cover shell to the metal outer wall of the metal pipe by magnetic adsorption.

[0021] In a preferred implementation, further, it also includes an observation window arranged on the side wall of the protective cover shell, and the observation window includes an embedded acrylic plate and a high-temperature sealing frame; and a sealing ring is provided on the bottom edge of the protective cover shell.

[0022] On the other hand, the present invention further provides a method for using a gas shield for in-situ repair of a metal pipeline by laser melting and forging based on any one of the above, the method comprising:

[0023] Step 1: Align the bottom profile of the protective cover shell with the outer surface of the metal pipe so that the repair area of the metal pipe is located inside the protective cover shell. Adjust the position of the electromagnetic fixing device and start the electromagnetic fixing device so that the protective cover shell fits tightly against the outer wall of the metal pipe.

[0024] Step 2: Connect the air inlet to the inert gas supply pipe, and the air outlet to the exhaust pipe or exhaust gas treatment device. Start the gas supply system and input inert gas from the air inlet to gradually fill the inside of the protective cover. At the same time, monitor the data of the oxygen content sensor to detect the oxygen concentration inside the protective cover.

[0025] Step 3: If the oxygen concentration is detected to be >100ppm, the air outlet is automatically opened while the gas input at the air inlet is maintained to perform gas replacement and discharge the high-oxygen gas. After the oxygen concentration drops to ≤100ppm, the flexible gas storage device is opened and inflated until the storage ball is full. The air inlet and outlet are closed, and the feedback from the pressure sensor is observed.

[0026] Step 4: Start the laser cladding equipment, select the corresponding cladding parameters, monitor the data of the pressure sensor in real time, use the temperature sensor to monitor the temperature inside the protective cover, and monitor the laser cladding process in real time through the acrylic plate;

[0027] Step 5: During the repair process, the flexible gas storage device automatically adjusts according to the changes in the internal airflow. When the air pressure drops, the storage ball releases the stored gas, and when the air pressure rises, the storage ball absorbs the excess gas. The sensor detects the oxygen content inside the protective cover. During the processing, the oxygen content is stabilized at 20ppm to 200ppm.

[0028] Step 6: After the repair is completed, stop the laser cladding equipment, turn off the laser cladding head and laser impact head, wait for the air pressure and temperature inside the protective cover to return to normal, turn off the electromagnetic fixing device, slowly remove the protective cover and clean the inside of the protective cover.

[0029] The beneficial effects of the present invention are:

[0030] First, the present invention is a gas protective cover for in-situ repair of metal pipes by laser melting. In order to solve the problems existing in the prior art, such as insufficient protection effect, delayed air pressure regulation, and poor sealing adaptability, the structural design has been systematically optimized. First, the present invention is able to achieve efficient sealing on complex arc surface structures by providing a protective cover shell with top and bottom openings, combined with a design in which the bottom profile is precisely matched with the outer surface of the metal pipe, thereby improving the fit and airtightness between the cover body and the outer wall of the pipe, avoiding oxygen penetration, and ensuring the stability of the repair area environment. Secondly, the present invention rationally arranges the air inlet and outlet on the side wall of the protective cover shell along the diagonal direction of the overall structure, optimizes the flow path of the inert gas inside the cover body, achieves a uniform distribution of the gas flow field, further reduces the local oxygen concentration, improves the protection effect during the cladding process, and avoids quality defects such as oxidation and pores of the cladding layer. Thirdly, the present invention incorporates a flexible shield on top of the protective cover, with an interface provided on the flexible shield for connection to the laser cladding head. Through its flexible material and circumferential sealing design, it ensures dynamic compatibility with the laser equipment while maintaining a closed protective space while ensuring free movement of the laser beam, thus meeting the dual requirements of flexibility and sealing during laser cladding repair. Furthermore, the present invention uniquely incorporates a flexible gas storage device, which includes a flexible gas storage ball, a gas storage ball interface, a valve plate, and a valve stem. This gas storage device automatically responds to changes in air pressure within the cover. When the pressure rises, the gas storage ball actively absorbs excess gas and releases the stored gas when the pressure drops, thereby dynamically regulating the pressure within the cover, effectively suppressing airflow fluctuations and ensuring atmosphere stability and cladding quality during the laser cladding process. Furthermore, the present invention incorporates an oxygen content sensor that can detect the oxygen concentration within the cover in real time. When the oxygen content is detected to be above a set threshold, the air inlet and outlet are opened to exchange gas, effectively overcoming the drawbacks of traditional protective covers that rely solely on passive negative pressure or manual adjustment. Finally, the present invention improves the stability of the cover during installation and use through a supporting and fixing device, ensuring that the protective cover can remain firmly fixed and well sealed under complex working conditions such as high temperature, high pressure and laser impact, further enhancing the reliability and durability of the overall system. In summary, the present invention overcomes the shortcomings of the existing technology through an innovative shell sealing structure, optimized airflow channel design, flexible interface layout, flexible gas storage and pressure regulation, and real-time oxygen content monitoring and control system, and improves the efficiency, stability and adaptability of gas protection during the laser melting and forging repair process of metal pipes, and has extremely high engineering application value and promotion prospects.

[0031] Second, in a preferred embodiment, the present invention incorporates an aluminum alloy mesh inside the balloon interface. This provides effective support for the balloon interface structure, preventing the balloon from expanding, deforming, or causing partial damage due to uneven force during pressure fluctuations.

[0032] Third, in the preferred implementation, the present invention realizes the functional division of local molten pool protection, atmosphere buffering and dynamic adjustment of air pressure by dividing the internal space of the protective cover shell into a melting and forging area, a processing area and a gas control area. The melting and forging area can effectively avoid quality defects such as oxidation, pores, inclusions, etc. caused by the intrusion of impurity gases such as oxygen and nitrogen during high-temperature melting. The processing area can further delay the interference of external air on the melting and forging area, form multiple barrier protections, and improve the overall atmosphere stability. The gas control area can respond to the changes in air pressure inside the cover in real time, and achieve dynamic balance of air pressure through automatic absorption and release of gas.

[0033] Fourth, in a preferred embodiment, the present invention incorporates pressure and temperature sensors within the protective housing to monitor pressure and temperature changes within the housing in real time. This real-time collected parameter information not only effectively warns of process risks caused by gas leaks and temperature anomalies, but also provides a basis for dynamic adjustment of the flexible gas storage device, precisely controlling the stability of the internal environment.

[0034] Fifth, in a preferred implementation, the present invention provides two independent mounting interfaces on the top of the flexible shield, which are used to install the laser cladding head and the laser impact strengthening head respectively, so that the laser cladding and laser impact strengthening operations can be carried out continuously in the same sealed space without the need for frequent equipment replacement or destruction of the protective atmosphere, thereby greatly improving the continuity and operating efficiency of the repair process.

[0035] Sixth, in a preferred embodiment, the supporting and fixing device of the present invention utilizes a combined electromagnet and wire rope structure. One end of the wire rope is hingedly connected to the protective cover housing, while the other end is mounted with an electromagnet. This design removably secures the protective cover housing to the metal outer wall of the metal pipe through electromagnetic attraction. This design not only enables the protective cover to be quickly and securely installed on metal pipes of varying curvatures and diameters, improving adaptability and ease of installation, but also, due to the electromagnetic force used for securing, it can be quickly de-energized and released after repair is complete, facilitating removal and relocation of the protective cover, avoiding the cumbersome operation and mechanical damage to the pipe surface associated with traditional mechanical fixing methods.

[0036] Seventh, in the preferred implementation, the present invention sets an observation window structure on the side wall of the protective cover shell. The observation window adopts an embedded acrylic plate with a high-temperature sealed frame design, which can realize real-time observation and monitoring of the internal working area of the cover during the laser melting and forging repair process, thereby improving the visibility of the operation and the controllability of the process. At the same time, a sealing ring is set at the bottom edge of the protective cover shell to further enhance the sealing performance between the protective cover and the outer surface of the metal pipe, effectively preventing external air infiltration and internal inert gas leakage.

[0037] Eighth, the method of using a gas protection cover for in-situ repair of a metal pipeline by laser melting and forging of the present invention can achieve efficient sealing protection and dynamic atmosphere control of the metal pipeline repair area, thereby improving the forming quality and operation stability during the laser melting and forging repair process. By precisely aligning the bottom profile of the protective cover shell with the outer surface of the metal pipe and using an electromagnetic fixing device to achieve a fast and secure seal, the problem of oxygen infiltration caused by insufficient sealing with traditional methods is avoided. Through the coordinated control of the inert gas supply system and the real-time oxygen content monitoring system, the atmosphere inside the cover can be quickly replaced and stably maintained, ensuring that the oxygen concentration is effectively reduced to ≤100ppm, significantly reducing the occurrence of defects such as oxidation and pores during the cladding process. The gas replacement is completed in 20 minutes, reducing the argon content inside the protective cover to below 100ppm. The introduction of a flexible gas storage device can automatically adjust the gas flow according to changes in the internal air pressure of the cover, achieving real-time air pressure balance and stabilizing the oxygen content of the protective cover at 20ppm to 200ppm, effectively suppressing the adverse effects of gas fluctuations on the stability of the cladding pool. During the laser cladding operation, the combination of pressure sensors, temperature sensors and acrylic plate windows for real-time monitoring further improves the controllability and refinement of the cladding process. After the repair is completed, the protective cover and pipe surface can be safely transitioned through orderly unloading and removal steps to avoid secondary damage to the repaired area. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of the three-dimensional structure of a gas protection cover for in-situ repair of a metal pipeline by laser melting and forging provided in Example 1 of the present invention;

[0039] Figure 2 A schematic cross-sectional view of the flexible gas storage device provided in Example 1 of the present invention;

[0040] Figure 3 This is a schematic diagram of the three-dimensional structure of the flexible gas storage device provided in Example 1 of the present invention when the gas storage ball protective shell is not assembled;

[0041] Figure 4 This is a schematic diagram of the overall three-dimensional structure of the flexible gas storage device provided in Example 1 of the present invention;

[0042] Figure 5 A schematic cross-sectional view of a gas protection cover for in-situ repair of a metal pipeline by laser melting and forging provided in Example 1 of the present invention;

[0043] Figure 6 A schematic flow chart of a method for developing an in-situ repair gas shield for a metal pipeline by laser melting and forging provided in Example 2 of the present invention;

[0044] Figure 7This is a simulation diagram of the argon concentration distribution of a gas protection cover for in-situ repair of a metal pipeline by laser melting and forging provided in Example 2 of the present invention;

[0045] Figure 8 A schematic flow chart of a method for using a gas protection cover for in-situ repair of a metal pipeline by laser melting and forging provided in Example 3 of the present invention;

[0046] Figure 9 A physical picture of the area to be repaired before the metal pipeline is repaired;

[0047] Figure 10 For Figure 9 The effect picture of the metal pipe to be repaired after grinding treatment;

[0048] Figure 11 This is a schematic diagram of the process of performing a repair operation using a metal pipeline laser melting in-situ repair gas protection cover as described in Example 3 of the present invention;

[0049] Figure 12 This is a physical picture of the metal pipeline area after the repair is completed using the method of using a gas protection cover for in-situ repair of a metal pipeline by laser forging described in Example 3 of the present invention.

[0050] Among them, 1-fixed connecting plate; 2-laser cladding head; 3-flexible joint; 4-air inlet; 5-protective cover shell; 6-sealing gasket; 7-electromagnet; 8-metal pipe; 9-air outlet; 10-flexible gas storage device; 10-1-gas storage ball protective shell; 10-2-gas storage ball; 10-3-gas storage ball interface; 10-4-aluminum alloy mesh; 10-5-valve stem; 11-steel wire rope; 12-flexible protective cover; 13-laser impact head; 14-acrylic plate; 15-oxygen content sensor; 16-pressure sensor; 17-temperature sensor. DETAILED DESCRIPTION

[0051] In order to enable those skilled in the art to better understand the technical solution of the present application, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0052] The terms "up", "down", "left", "right", "front", and "back" in this application are based on the positional relationships shown in the accompanying drawings. The corresponding positional relationships may vary depending on the drawings, and should not be construed as limiting the scope of protection.

[0053] In this application, the terms "installed," "connected," "connected," "connected," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, integral connection, mechanical connection, electrical connection, or mutual communication. They can also be directly connected or indirectly connected through an intermediate medium. They can also refer to internal communication between two components or interaction between two components. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0054] The present invention aims to provide a gas shield for in-situ laser melting and forging repair of metal pipes and its use method. The gas shield, by providing a flexible gas storage ball structure, can automatically adjust the gas pressure when the gas flow fluctuates, ensuring a stable gas protection environment and improving the quality of the melting and forging repair. By integrating an oxygen content sensor, a pressure sensor, and a temperature sensor, the protective gas environment is monitored in real time. Combined with the adjustment of the air inlet and outlet, the oxygen content is ensured to remain stable within a safe range. A stable gas protection environment can effectively reduce oxidation in the melting and forging zone, improve the metallurgical bonding quality of the cladding layer, and enhance the wear resistance and corrosion resistance of the metal pipe. Furthermore, the gas shield is divided into a melting and forging zone, a processing zone, and a gas control zone, optimizing the gas flow in different functional areas and improving the repair accuracy and stability. The shield shell adopts a bottom arc fitting design, combined with a high-efficiency sealing ring, to achieve precise fitting to the outer wall of the metal pipe, effectively preventing the ingress of external air and enhancing the gas protection effect. The flexible gas storage device can buffer gas flow fluctuations, and the electromagnetic fixing device ensures that the repair process is smooth, improving equipment stability and reducing the impact of external interference on the repair quality. Through innovative structural design and gas control system, the present invention breaks through technical bottlenecks such as unstable gas protection, low repair accuracy, and insufficient applicability in the existing metal pipeline repair process, providing an efficient, stable, and safe solution for laser melting and forging repair of metal pipelines.

[0055] Example 1

[0056] Refer to the instruction manual Figure 1-5A gas protective cover for in-situ repair of metal pipes by laser melting and forging, comprising a protective cover shell 5, a flexible gas storage device 10, a flexible shield 12, an oxygen content sensor 15 and a steel wire rope 11, is used to provide a stable gas protection environment during the laser melting and forging repair process of metal pipes. The protective cover shell 5 adopts an open structure with the top and bottom connected, and is provided with a sealed enclosure to form an independent repair space. Its bottom profile precisely matches the outer surface of the metal pipe 8 to ensure a tight fit to effectively cover the repair area of the metal pipe 8. The flexible shield 12 is arranged on the top of the protective cover shell 5 and is circumferentially connected along the top edge of the protective cover shell 5 to form a metal pipe repair space with the protective cover shell 5. A connection interface for the working head of the laser cladding equipment is provided at the top of the flexible shield 12, which is used to enclose the working head of the laser cladding equipment in the metal pipe repair space formed by the flexible shield 12 and the protective cover shell 5. The laser cladding equipment is connected to an external movable device, and the laser cladding equipment is driven to move by the external movable device to achieve dynamic repair. The bottom profile of the protective cover shell 5 matches the arc surface of the metal pipe 8, and is used to fit with the outer surface of the metal pipe 8, so that the repair area of the metal pipe 8 is accommodated in the inner cavity of the protective cover shell 5. The air inlet 4 is provided on one side of the upper part of the protective cover shell 5, and the air outlet 9 is provided on the opposite side of the lower part of the protective cover shell 5 or on the side at 90° to the air inlet 4. The air inlet 4 and the air outlet 9 are arranged along the diagonal direction of the protective cover shell to form a stable gas flow path, improve the coverage efficiency of the protective gas, and prevent impurities from entering the melting and forging area. The gas entering the interior of the protective cover shell 5 is an inert gas, and argon is selected as the inert gas. A supporting and fixing device is provided on the side of the protective cover shell 5, which adopts an electromagnetic fixing method to fix the protective cover shell 5 to the outer wall of the metal pipe 8, ensuring the stability of the device during the repair process and avoiding displacement affecting the cladding quality.

[0057] The oxygen content sensor 15 is arranged inside the protective cover shell 5. The oxygen content sensor 15 is connected to the external control system through a data line and is used to measure the oxygen concentration inside the protective cover shell 5 to ensure that the operating environment meets the safety requirements of the laser cladding process and prevent unstable cladding quality or material oxidation caused by a high-oxygen environment. When the oxygen content measured by the oxygen content sensor 15 is greater than 100ppm, it means that there is still excess oxygen inside the protective cover shell 5. The system needs to perform gas replacement. The air inlet 4 and the air outlet 9 are opened at the same time, the air inlet 4 inputs argon gas, and the air outlet 9 removes high-oxygen gas to reduce the oxygen concentration inside the protective cover. The oxygen in the protective cover shell 5 is gradually removed until the oxygen content measured by the oxygen content sensor 15 is reduced to ≤100ppm. According to the pressure inside the protective cover shell 5, the air inlet 4 and the air outlet 9 are controlled to be closed at the same time, or the air outlet 9 is closed and the air inlet 4 continues to input argon gas until the pressure meets the operating requirements.

[0058] The internal space is divided into a melting zone, a processing zone, and a gas control zone to optimize gas environment control and operational precision during the laser melting repair of metal pipelines. The melting zone is the direct area of action of the laser cladding equipment's working head. The working head interface for the laser cladding equipment is located at the top of the melting zone and is responsible for laser melting repair of defective areas of the metal pipeline. The melting zone is directly exposed to the laser energy and has the highest temperature.

[0059] The flexible gas storage device 10 is arranged around the melting and forging area, and a gas storage ball 10-2 is provided inside the gas storage ball 10-2. The gas storage ball 10-2 has an interface that communicates with the melting and forging area on the side wall of the protective cover shell 5. A valve is provided between the interface of the gas storage ball 10-2 and the side wall of the protective cover shell 5. The valve is used to control the opening and closing of the interior of the protective cover shell 5 and the inner cavity of the gas storage ball 10-2. When the oxygen concentration inside the protective cover shell 5 drops to ≤100ppm, the gas inside the protective cover shell 5 enters the gas storage ball 10-2 by opening the valve, and the gas storage ball 10-2 inflates to form an additional buffer space. When the working head of the laser cladding equipment moves, causing disturbances in the gas flow field inside the protective cover shell 5, causing turbulence or loss of the protective gas inside the protective cover, resulting in a drop in the air pressure inside the protective cover shell 5, the gas storage ball 10-2 quickly releases part of the stored gas to maintain internal pressure stability. On the contrary, if the pressure rises briefly, the gas storage ball 10-2 absorbs excess gas to avoid excessive airflow affecting the quality of forging, achieve adaptive pressure regulation, ensure the stability of the gas environment during the laser cladding process, and ensure that the cladding layer forms a dense, high-quality surface without oxide inclusions.

[0060] The processing area is located outside the melting and forging area, providing dynamic adjustment space for the laser processing process, including cladding layer formation, temperature control and material flow adjustment. This area contains an air inlet 4 and an air outlet 9, which are arranged diagonally to form a stable gas circulation path to remove impurity gases and high-temperature smoke, thereby improving the cladding effect. The observation area is located on the side or top of the protective cover shell 5, and is used to monitor the cladding process in real time to ensure that the repair quality is controllable. The gas control area is located on the side or top of the protective cover shell 5, and is responsible for controlling the input, circulation and discharge of the protective gas to ensure a stable atmosphere environment in the melting and forging area. This area includes a flexible gas storage device 10, which is connected to the external gas supply system through an inflation interface to achieve real-time gas replenishment and voltage stabilization control.

[0061] In a preferred embodiment of this application, oxygen sensor 15 is located above the processing area, near the main gas flow channel, ensuring accurate detection of oxygen concentration levels in the working area. Oxygen sensor 15 feeds data back to an external central control system (PLC or industrial computer). When oxygen concentration exceeds the standard, the shielding gas flow rate is automatically adjusted to optimize the forging environment.

[0062] In a preferred embodiment of the present application, the flexible gas storage device 10 further includes a gas storage ball protective shell 10-1, a gas storage ball interface 10-3, an aluminum alloy mesh 10-4, and a valve stem 10-5. One end of the gas storage ball interface 10-3 communicates with the interior of the gas storage ball 10-2, while the other end communicates with a fused connection interface on the sidewall of the protective cover shell 5, thereby establishing a gas exchange channel between the gas storage unit and the system. The gas storage ball protective shell 10-1 is positioned over the exterior of the gas storage ball 10-2 and the gas storage ball interface 10-3 for mechanical protection and is securely fixed to the sidewall of the protective cover shell 5 by bonding.

[0063] The valve disc and valve stem 10-5 together form the control valve structure. The valve disc is located within the ball reservoir port 10-3 and is connected to it via the valve stem 10-5, controlling the valve's opening and closing state within the passageway of the ball reservoir port 10-3. The valve stem 10-5 extends through the exterior of the ball reservoir housing 10-1, facilitating manual operation to open and close the valve. To ensure stable operation, the valve stem is fitted with a bearing assembly. The bearing seat is mounted within the ball reservoir housing 10-1 to support its rotation.

[0064] An aluminum alloy mesh 10-4 is installed inside the gas storage ball interface 10-3 and can be secured by bonding or welding. Aluminum alloy mesh 10-4 has multiple functions: First, it serves to rectify airflow, preventing gas from entering and exiting the gas storage ball 10-2 in an instantaneous impact manner, thereby improving system stability. Second, it helps maintain gas pressure balance and reduces system stress caused by airflow fluctuations. Third, it acts as a gas filter, effectively intercepting particulate impurities in the gas and protecting the valve and the internal structure of the gas storage ball from contamination. Fourth, it blocks the conduction of high-temperature gas and prevents heat from entering the gas storage ball. Fifth, it provides the necessary mechanical support and structural strength to ensure that the valve stem and valve disc do not deform or loosen under high-frequency use, thereby improving the reliability and durability of the device.

[0065] The protective cover shell 5 and the balloon protective shell 10-1 are both made of aluminum alloy. The balloon 10-2 is made of a high-temperature resistant and expandable flexible material, such as high-temperature heat-resistant silicone rubber, high-temperature resistant fluororubber (Viton), polyimide film (Kapton) or polymer composite film (such as PBO fiber composite material).

[0066] In the preferred implementation of the present application, two mounting ports are provided on the top of the flexible shield 12 for mounting a flexible joint 3, the main function of which is to ensure that the laser cladding head 2 and the laser impact head 13 have good airtightness during operation, while allowing moderate displacement and angle adjustment to adapt to different processing requirements. The flexible joint 3 is made of high-temperature resistant, high-strength, and corrosion-resistant materials (such as silicone rubber, fluororubber, PTFE composite materials or metal bellows) to ensure that it maintains stable performance in a high-temperature, high-energy laser environment and has good flexibility to reduce resistance and deformation during operation of the laser head. The laser cladding head 2 is used for high-precision metal cladding repair. The laser beam heats the surface of the substrate to melt the alloy powder or filler material and form a metallurgically bonded cladding layer to enhance the wear resistance, corrosion resistance and mechanical strength of the metal pipe. The laser impact head 13 is used for laser shock strengthening. A high-energy short-pulse laser generates a plasma shock wave on the metal surface, triggering an ultra-high pressure stress wave on the surface of the material, thereby increasing the residual compressive stress of the metal and improving fatigue resistance and crack propagation resistance.

[0067] The laser cladding head 2 and the laser percussion head 13 are mounted together on a fixed connecting plate 1. This connecting plate is made of a high-strength alloy material (such as aviation aluminum alloy or stainless steel), ensuring a rigid structure that can withstand the reaction forces during cladding and impact, while also providing a certain degree of shock absorption to reduce the impact of vibration on processing quality. The fixed connecting plate 1 is connected to external processing equipment via a guide rail or robotic arm, allowing laser cladding and laser percussion to be applied simultaneously to the pipe surface, reducing processing time and ensuring that the two repair processes are precisely aligned in the same processing area, improving processing accuracy and repair quality.

[0068] In a preferred embodiment of the present application, a gas shield for in-situ repair of metal pipes by laser melting and forging also includes a pressure sensor 16 and a temperature sensor 17 installed inside the protective shield shell 5, which are used to accurately detect key process parameters in the protective shield cabin, ensure a stable atmosphere environment, and improve the repair quality and process control capabilities. The pressure sensor 16 is located on the inner wall of the protective shield shell 5, close to the gas inlet and the negative pressure exhaust port, to monitor the dynamic changes in the gas pressure in the cabin. By real-time detection of the pressure stability in the gas shield, it is ensured that the gas flow during the laser melting and forging process or external environmental interference will not cause the air pressure to drop, affecting the protection effect. When the pressure is lower than the set threshold, the system can automatically increase the inflation rate or adjust the exhaust rate to maintain a stable positive pressure environment and prevent external air from infiltrating. The temperature sensor 17 is arranged around the processing area inside the protective shield cabin, preferably placed in the position that may be most affected by the laser heat, so as to obtain accurate temperature data. By monitoring the temperature changes in the cabin, it is ensured that there are no overheating or insufficient cooling problems during the repair process. The data collected by these sensors are transmitted to the industrial computer (PLC / CNC system) in real time via a high-speed data bus (such as CAN bus, RS485 or wireless transmission module).

[0069] In the preferred implementation of the present application, the supporting and fixing device includes an electromagnet 7 and a steel wire rope 11. The steel wire rope 11 is made of high-strength alloy material to enhance the load-bearing capacity and improve durability. One end of the steel wire rope is hingedly connected to the side of the protective cover shell 5 through a high-strength hinge to achieve a rotatable adjustment function. Figure 1 For example, the protective cover housing 5 is designed as a rectangular structure, with four sets of steel ropes 11 arranged on its four sides to ensure stability. Electromagnets 7 are installed at the other end of the steel ropes 11 to provide strong magnetic attraction, allowing the steel ropes 11 to be quickly attracted and fixed to the outer wall of the metal pipe 8.

[0070] Through the electromagnetic control system, the electromagnet 7 can realize controllable adjustment of the magnetic force. When powered on, the electromagnet 7 generates a strong magnetic field, forming a high-strength adsorption with the metal base, ensuring that the protective cover shell 5 is firmly fixed to prevent vibration or displacement. When the power is turned off, the magnetic field disappears, the steel wire rope 11 is released, and can be freely adjusted or disassembled, making it convenient for the disassembly or position adjustment of the protective cover. Since the electromagnetic adsorption fixing method has no mechanical locking structure, the electromagnetic adsorption method can provide instantaneous high-strength fixing force, adapt to vibration conditions, effectively reduce the impact of external force vibration on the protective cover, and improve the stability of the equipment. The electromagnet 7 replaces the traditional mechanical locking mechanism, improving the flexibility and ease of operation of the equipment.

[0071] In a preferred implementation of the present application, a metal pipe laser melting in-situ repair gas protection cover further integrates an observation window assembly, which includes an acrylic plate 14 for real-time monitoring of the repair process to ensure visualization and safety of the operation. The acrylic plate 14 is installed in the side wall observation area of the protective cover shell 5 as an observation window to meet the operator's visualization needs while taking into account high temperature resistance, impact resistance and oxidation resistance. The acrylic plate 14 adopts an embedded installation structure, embedded in the observation window reserved in the protective cover shell 5, and is sealed and fixed by a high-temperature heat-resistant silicone sealing strip or a high-temperature resistant metal frame to ensure airtightness and prevent leakage of protective gas. The edge of the acrylic plate 14 is fixed with high-strength heat-resistant screws or clips to ensure structural stability under high-temperature working conditions.

[0072] In the preferred implementation of the present application, a circle of high-efficiency sealing structure is arranged at the edge of the bottom arc surface of the protective cover shell 5 to ensure a close fit with the outer wall of the metal pipe, prevent the entry of external air or leakage of protective gas, thereby improving the gas protection effect and ensuring a stable environment in the repair area. The sealing structure adopts a sealing ring with a U-shaped, V-shaped or Ω-shaped cross-section design, which uses its own elastic deformation to form a close fit with the pipe surface, effectively preventing gas leakage. The sealing ring adopts a high-temperature resistant and corrosion-resistant elastic sealing material (such as silicone rubber, fluororubber or polytetrafluoroethylene (PTFE)) to adapt to the high temperature, high pressure and corrosive environment of metal pipes.

[0073] Furthermore, a slot is provided at the bottom of the protective cover housing 5, which allows for embedded installation, securing the sealing ring to the bottom edge of the protective cover housing 5 and ensuring replaceability. Alternatively, a magnetic seal can be employed, utilizing a high-strength magnetic sealing strip that automatically adheres to the surface of the metal pipe, making it suitable for rapid sealing of metal pipes.

[0074] In the preferred implementation of the present application, the air inlet 4 is equipped with a flow control valve for controlling the flow of the protective gas entering the protective cover to ensure that the smelting and forging area has sufficient supply of protective gas. The flow control valve adopts a one-way valve structure, which only allows gas to flow in the set direction to prevent gas backflow caused by pressure fluctuations or environmental interference during the smelting and forging process, thereby ensuring the stability of the system. The flow control valve can be adjusted manually or by an electric adjustment mechanism (such as a spiral or electromagnetic proportional control valve) to finely adjust the valve opening. A flow sensor can also be used to monitor the flow in real time, and automatically optimize the gas supply in combination with a control system.

[0075] Outlet 9 is equipped with a pressure-regulating valve to control the gas pressure inside the protective cover, ensuring that the air pressure in the forging area remains within the optimal range and preventing airflow disturbances that could affect forging quality. The pressure-regulating valve utilizes a one-way valve structure to ensure that gas can only flow out from within the protective cover, preventing backflow. This prevents outside air from entering the protective cover and affecting the purity of the protective atmosphere. The pressure-regulating valve can be adjusted automatically or manually using a spring-loaded adjustment mechanism or an electric servo control system to match the exhaust pressure requirements of different materials and processes. It can also be combined with a pressure sensor to achieve closed-loop control, ensuring real-time adjustment of the output pressure and improving the stability of the repair process.

[0076] Compared with the gas protection covers in the prior art, the gas protection cover for in-situ repair of metal pipelines by laser melting and forging of the present invention has the following advantages:

[0077]

[0078]

[0079] Example 2

[0080] Refer to the instruction manual Figure 6-7 Based on the metal pipeline laser melting in-situ repair gas protection cover structure of Example 1, this embodiment proposes a method for developing a metal pipeline laser melting in-situ repair gas protection cover, the method comprising:

[0081] Step 1: Use three-dimensional modeling software to construct the overall structure of a metal pipe laser melting in-situ repair gas protection cover. The overall structure includes a protection cover shell, an air inlet and an air outlet arranged on the protection cover shell, a flexible protection cover arranged on the top of the protection cover shell, a sealing gasket located at the bottom of the protection cover shell, a flexible gas storage device installed on the side of the protection cover shell, a supporting and fixing device integrated in the side of the protection cover shell, and a sensor installation position for collecting gas parameters inside the cover.

[0082] It should be noted that the three-dimensional modeling uses conventional design software, such as SolidWorks software.

[0083] Specifically, step 1 includes:

[0084] Step 1.1: Based on the outer diameter of the metal pipe, design a rectangular protective cover body with a concave arc-shaped bottom structure to match the outer surface of the metal pipe. The top and bottom of the protective cover body are both set as connected opening structures.

[0085] In the application's implementation, the protective cover body measures 900mm by 900mm in length and width, with an overall height (H1) of 400mm, ensuring ample gas flow to maintain a stable protective atmosphere in the forging zone. The arc height (H2) of the concave arc structure at the bottom, which matches the profile of the metal pipe, is set at 200mm. This allows the protective cover to precisely fit within a 200mm radius metal pipe, creating a sealed connection and improving shielding gas utilization.

[0086] Step 1.2: Design a flexible shield along the circumference of the top edge of the shield body, and design two laser head mounting ports on the top of the flexible shield for cladding and impact respectively.

[0087] The flexible shield allows the laser cladding head and the laser impact head to move freely.

[0088] Step 1.3: Based on the process requirements of laser melting and forging repair, the internal space of the protective cover shell is divided into functional areas: a melting and forging area located below the two laser heads, a processing area located outside the melting and forging area, and a gas control area and an observation area located on the sides of the protective cover shell.

[0089] Step 1.4: Design the air inlet and outlet in the processing area. The air inlet is designed on the upper part of the protective cover body, and the air outlet is arranged along the diagonal direction of the protective cover body and designed on the lower part of the protective cover body. Design a flow regulating valve at the air inlet and a pressure regulating valve at the air outlet.

[0090] In the implementation of the application, the inner diameters of the air inlet and outlet are 40 to 60 mm. The pressure regulating valve ensures that the oxygen concentration in the forging area is less than 500 ppm and maintains a slight positive pressure (0.1 to 0.8 MPa).

[0091] Step 1.5: Design the flexible gas storage device in the gas control area of the protective cover body, design the acrylic plate in the observation area outside the protective cover shell, and design the pressure sensor and temperature sensor in the processing area inside the protective cover shell.

[0092] In the implementation of the application, a 200mm×300mm rectangular hole is opened in the observation area outside the protective cover shell for installing an acrylic plate.

[0093] When designing a flexible gas storage device, it is necessary to ensure that the internal pressure P of the protective cover env Always maintain a certain target working pressure range [P env,min ,P env,max ] inside. Since the storage ball is connected to the inside of the protective cover, based on the thermodynamic equilibrium state - the gas in the connected container will eventually tend to pressure equilibrium due to the free movement of molecules, it is believed that under the conditions of no control valve, unobstructed pipelines, and the system being stationary, the internal pressure of the protective cover Penv Equal to the internal pressure P of the sphere.

[0094] The spherical storage ball is a thin-walled spherical container that conforms to the elastic small deformation assumption. Starting from the stress safety condition, the radius r is determined according to the pressure requirement, and the required sphere radius r is inferred using the following formula:

[0095]

[0096] Where: t represents the wall thickness of the spherical ball (since the wall thickness t of the spherical ball is very small, generally in the mm range, the wall thickness t is set using engineering experience, and t is generally recommended to be 2 mm); σ max Indicates the maximum safety stress of the material of the spherical ball; P max Indicates the maximum allowable internal pressure of the sphere (slightly higher than the target working pressure); P env Indicates the air pressure inside the protective cover.

[0097] It should be noted that σ max It is the maximum tensile stress that a material can withstand without plastic deformation or damage. It is directly related to the material selection and is a known parameter. max It is the maximum gas pressure allowed inside the spherical storage ball. Exceeding this value may cause the material to yield or burst. It is obtained based on the stable gas pressure value that needs to be maintained inside the protective cover under normal working conditions. According to engineering experience, P is set max =1.2~1.5×P env,max , avoid critical state and leave a safety margin. env It is the target working air pressure inside the protective cover and the basis for gas exchange and buffer control. It can be set according to the system function requirements.

[0098] Therefore, the above setting parameter σ max 、P max and P env Substituting into formula (1), we can get the spherical radius r of the spherical storage ball.

[0099] Furthermore, the maximum effective volume V0 of the balloon is calculated. Assuming that the balloon is a spherical balloon, its volume V0 when not inflated is calculated using the sphere volume formula:

[0100]

[0101] Where: r represents the radius of the storage ball.

[0102] Considering the influence of the material thickness t, the actual volume of the gas inside the spherical ball (excluding the spherical shell) can be expressed as:

[0103]

[0104] Furthermore, the adaptability of volume changes to working pressure was verified. The actual regulating ability of the spherical shell comes from the elastic change of its volume. Since the spherical shell deforms isotropically (i.e., expands in three dimensions) when subjected to force, the following approximate formula is used to evaluate the gas pressure response:

[0105] V=V0(1+3ε) (4)

[0106] Where: V represents the volume of the storage ball after the change of the storage ball.

[0107] According to Hooke's law, the relative deformation degree of the sphere wall caused by the change of internal air pressure is obtained:

[0108]

[0109] Where: ε represents strain; σ represents the tensile stress on the sphere wall caused by the pressure difference between the inside and outside of the sphere; E represents the elastic modulus of the sphere material (Pa).

[0110] According to formula (1), the tensile stress σ of the ball wall caused by the internal and external pressure difference of the ball storage ball is obtained:

[0111]

[0112] Where: σ represents the current stress of the sphere wall; P represents the current gas pressure inside the sphere; P env represents the working pressure of the gas shield; r represents the radius of the gas storage ball; t represents the thickness of the gas storage ball wall.

[0113] To ensure that the material does not exceed the elastic limit, σ≤σ max ,σ max is the maximum allowable stress of the material (Pa).

[0114] Substituting formulas (5) and (6) into formula (4), we can obtain the volume V of the balloon after deformation:

[0115]

[0116] Combined with formula (7), the ideal gas state equation is used to calculate its volume change under temperature change:

[0117]

[0118] Where: P represents the actual pressure of the gas inside the current storage ball (Pa); V represents the current volume of the storage ball (m 3 ); n represents the number of moles of gas; R represents 8.314 J / (mol·K); T represents the current temperature (K); V0 represents the initial reference volume of the storage ball (m 3 );P envrepresents the working pressure of the gas shield (Pa); r represents the radius of the gas storage ball; t represents the wall thickness of the gas storage ball; E represents the elastic modulus of the gas storage ball material (Pa).

[0119] It should be noted that n is the total amount of gas inside the balloon, which changes with inflation / deflation, dynamically responding to the gas exchange in the protective cover. R is the thermodynamic constant, applicable to all ideal gases. T is the thermal environment temperature of the gas storage system, which can be measured by a temperature sensor. V0 is the volume of the balloon in the absence of deformation and pressure difference, which is the reference value for calculating volume change. env = is the current pressure in the protective cover space connected to the balloon, affecting the direction of gas inflow and outflow and the volume response. r is used to estimate the degree of deformation of the spherical structure, affecting the degree of stress and volume change. t determines the material's resistance to deformation and affects the elastic response of the balloon. E represents the stiffness of the material (such as silicone rubber and TPU), reflecting the linear slope of the stress-strain relationship.

[0120] Formula (8) is a self-closed-loop expression for the ball storage system's pressure regulation response. It describes how the internal pressure of the ball storage system automatically adjusts to external pressure fluctuations under specific conditions: gas volume n, temperature T, structural parameters r,t, and material parameters E. nRT represents the thermodynamic energy of the gas per unit time, reflecting the ideal gas portion of the system's pressure. If n increases (gas is added), pressure P increases. If the temperature rises, molecular kinetic energy increases, and pressure increases. It represents the volume of the sphere after elastic expansion / contraction driven by pressure difference. Is the elastic volume change part, PP env It is the pressure difference driving source, the size of the internal pressure of the storage ball relative to the external pressure (the internal pressure of the protective cover); the larger the radius r of the storage ball, the more obvious the deformation (stress amplification); the larger the wall thickness t, the stronger the deformation resistance (suppressing volume change); the higher the elastic modulus E, the stronger the structural rigidity (smaller the adjustment range).

[0121] When the working pressure of the gas shield P env During ascent, the gas in the protective cover is pushed into the spherical storage ball from the protective cover, and the pressure difference P env >P, gas flows into the storage ball, the storage ball automatically expands and "inflates", the gas volume n in the storage ball increases, as the storage ball expands, the pressure and volume in the storage ball rise synchronously, the storage ball plays a role in absorbing overpressure, and buffering the pressure rise of the protective cover. When the working pressure P of the gas protective cover env When descending, the pressure inside the spherical storage ball is higher than that inside the protective cover, and the pressure difference P env <P, the gas flows back into the protective cover, the storage ball releases the gas and automatically contracts, and the gas amount n in the storage ball decreases. As the storage ball contracts, the pressure and volume in the storage ball decrease synchronously. The storage ball plays a role in replenishing gas and stabilizing pressure, alleviating the risk of sudden pressure drop in the protective cover.

[0122] Furthermore, according to formula (8), the internal pressure P of the protective cover is obtained. env Calculation formula:

[0123]

[0124] Formula (9) is the air pressure P inside the protective cover env The closed-loop relationship between the state and structural parameters of the storage ball itself. By adjusting the structural parameters r and t, material parameters E, initial volume V0, and gas filling amount n of the storage ball, its effect on the internal pressure P of the protective cover can be effectively controlled. env The influence of P env ∈[P env,min ,P env,max ] to achieve stable regulation of pressure within the desired working range.

[0125] Step 1.6: Design a groove on the bottom surface of the protective cover body. Design the sealing ring structure according to the groove profile and groove size.

[0126] Step 1.7: Design articulated support fixtures on the four sides of the protective cover shell, and design an electromagnet at the bottom of each support fixture.

[0127] Step 2: Use flow field analysis software to simulate the flow field of the three-dimensional model constructed in step 1, analyze the flow uniformity and oxygen concentration distribution of the protective gas, and when the simulation results meet the set requirements, proceed to step 3. If the simulation results do not meet the expected performance indicators, return to step 1, adjust the structure and related parameters of the protective cover, and re-simulate the flow field until the design requirements are met.

[0128] It should be noted that conventional flow field analysis software, such as ANSYS Workbench and Fluent software, is used.

[0129] Specifically, step 2 includes:

[0130] Step 2.1: Perform flow field simulation on the three-dimensional model constructed in step 1. Use tetrahedron adaptive meshing to divide the model. Set the mesh size to 0.5 mm, ensure that the mesh quality is greater than 0.85, and the maximum skewness is less than 0.65.

[0131] Step 2.2: Simulate the gas flow based on the standard k-ε turbulence model. Set the shielding gas to argon, the inlet velocity to 1–1.5 m / s, the outlet pressure to ambient atmospheric pressure, the wall condition to a no-slip boundary, and the initial ambient gas to air.

[0132] Step 2.3: Based on the simulation results, analyze the gas flow uniformity and oxygen concentration distribution to ensure that the flow velocity in the forging area is stable at 0.5-1.1 m / s and verify that the oxygen concentration in the forging area is stable below 500 ppm.

[0133] Refer to the instruction manual Figure 7 , Figure 7 This is a three-dimensional model of a metal pipe laser melting in-situ repair gas shield constructed according to step 1, and a schematic diagram of the argon content simulation obtained according to the parameters set in steps 2.1-2.2. Figure 7 A in the figure represents the initial state, in which the protective cover has not yet been filled with argon and is in an ambient air state as a whole. The argon mass fraction is close to 0.000 and appears dark blue. Figure 7 Figure B shows the simulation result 10 seconds after the argon gas enters the protective cover. The argon gas begins to enter the protective cover from the inlet, but the overall coverage is small, with only a slight increase in the area near the inlet. The argon mass fraction is still low, and the color becomes slightly brighter. Figure 7 Figure C shows the simulation result 20 seconds after the argon gas enters the image. The argon gas further diffuses, and a thin argon layer begins to form in the top area. The overall gas distribution is relatively uniform, but there is still residual air, and the color gradually transitions to light blue. Figure 7 D in the figure is the simulation result 1 minute after argon gas enters. Most of the argon gas covers the internal space of the protective cover, but a small amount of air still remains at the bottom. The argon concentration increases and the color transitions to turquoise. Figure 7 Figure E is the simulation result 3 minutes after argon gas entered. The argon gas has basically filled the interior of the protective cover, the air at the bottom has decreased, the oxygen concentration in the protected area has dropped significantly, and the color has changed to yellow-orange, indicating that the argon gas content is close to saturation. Figure 7 The figure F represents the simulation result 4 minutes and 20 seconds after argon enters the shield. The argon completely covers all areas within the shield, essentially displacing the air. A stable protective atmosphere is formed within the shield, with an argon mass fraction approaching 1.000 and an overall red color. The simulation results analyze the uniformity of the gas flow. After entering from the upper inlet, the gas forms a laminar blanket along the inner wall of the shield. The flow velocity is highest near the top inlet, and the flow velocity in the forging area stabilizes at 0.5 to 1.1 m / s, meeting the anti-oxidation requirements. The oxygen concentration distribution is analyzed, and the oxygen concentration in the forging area is less than 500 ppm, verifying the effectiveness of the shield in isolating the air. The flow control valve and pressure control valve work together to dynamically adapt to different operating conditions.

[0134] Step 3: Determine the material of each component of the gas shield for in-situ repair by metal pipe laser forging.

[0135]

[0136]

[0137] Example 3

[0138] Refer to the instruction manual Figure 8 A method for using a gas shield for in-situ repair of a metal pipeline by laser melting and forging, the method comprising:

[0139] Step 1: Align the bottom profile of the protective cover shell with the outer surface of the metal pipe so that the repair area of the metal pipe is located inside the protective cover shell, adjust the position of the electromagnetic fixing device, and start the electromagnetic fixing device so that the protective cover shell fits tightly against the outer wall of the metal pipe.

[0140] Step 2: Connect the air inlet to the argon supply pipe, connect the air outlet to the exhaust pipe or exhaust gas treatment device, start the gas supply system, input argon from the air inlet, gradually fill the inside of the protective cover, and at the same time monitor the data of the oxygen content sensor to detect the oxygen concentration inside the protective cover.

[0141] Step 3: If the oxygen concentration is detected to be >100ppm, the air outlet will be automatically opened while the gas input to the air inlet is maintained to perform gas replacement and discharge the high-oxygen gas. After the oxygen concentration drops to ≤100ppm, the flexible gas storage device will be opened and the gas storage ball will be inflated until it is full. The air inlet and outlet will be closed, and the feedback from the pressure sensor will be observed.

[0142] Step 4: Start the laser cladding equipment, select the corresponding cladding parameters, monitor the data of the pressure sensor in real time, use the temperature sensor to monitor the temperature inside the protective cover, and monitor the laser cladding process in real time through the acrylic plate.

[0143] Step 5: During the repair process, the flexible gas storage device automatically adjusts according to the changes in internal airflow. When the air pressure drops, the storage ball releases the stored gas, and when the air pressure rises, the storage ball absorbs excess gas.

[0144] Specifically, during repair, the laser cladding head focuses the laser beam on the defective area of the pipe, heating the metal surface to be repaired until it melts. Alloy powder is evenly sprayed through a powder nozzle, melting it with the surface to be repaired and forming a metallurgically bonded cladding layer. Argon gas within the protective hood provides protection. After one layer of cladding is completed, the equipment is adjusted to process the next layer, and the uniformity of the cladding layer is controlled through a layer-by-layer stacking process. Short laser pulses from the laser impact head act on the surface of the cladding layer, generating a high-energy plasma shock wave. This shock wave generates instantaneous high-pressure stress, increasing the density of the material surface and introducing residual compressive stress, improving crack propagation resistance. A flexible gas storage device within the protective hood adjusts the airflow in real time to ensure stable pressure during the impact process. Depending on the application scenario, the laser cladding head and laser impact head can perform a layer-by-layer cladding and impacting process. That is, after each layer is clad, the laser impact head is immediately used to strengthen that layer before cladding the next layer. Alternatively, after all cladding layers are deposited, a full-scale laser shock peening process can be performed, allowing the shock wave to act on the entire cladding layer.

[0145] Step 6: After the repair is completed, stop the laser cladding equipment, turn off the laser cladding head and laser impact head, wait for the air pressure and temperature inside the protective cover to return to normal, turn off the electromagnetic fixing device, slowly remove the protective cover and clean the inside of the protective cover.

[0146] As the instruction manual Figure 9-12 , combined with steps 1 to 6, the specific process of implementing the present invention is as follows:

[0147] In the attached Figure 9 In the image above, a square area has been demarcated on the metal pipe surface, marking the defect area to be repaired. Before repair, visual inspection and nondestructive testing (such as ultrasonic or magnetic particle testing) are performed to confirm the defect type and distribution. The repair boundary is then defined to ensure that the defect is completely contained within the repair area. Subsequently, necessary cleaning is performed around the demarcated area to remove surface oil, oxides, and other deposits to ensure the quality of the subsequent repair.

[0148] like Figure 10 As shown, the repaired area is mechanically polished. The polishing depth is determined by the defect depth and is typically within a range of 0.5 to 1.0 mm from the substrate surface. The polished surface should exhibit a uniform roughness to facilitate metallurgical bonding during subsequent laser cladding. After polishing, wipe or blow with a dust-free cloth to ensure that no visible particles remain in the polished area.

[0149] Go to step 2 and fix the protective cover on the surface of the metal pipe according to the repair process requirements (see Figure 11). The protective cover adopts a flexible sealing device, which fits tightly to the curved surface of the pipe to ensure air tightness. The air inlet of the protective cover is connected to the gas supply system through a hose, and argon gas is started to be input into the inside of the cover to replace the internal air and reduce the oxygen concentration. During the initial inflation stage, the oxygen concentration in the cover is monitored in real time. If the oxygen content drops below 100ppm and is still unstable, the air outlet continues to be opened for gas replacement until the oxygen concentration in the cover stably drops to below 20ppm. In an embodiment of the present invention, it usually takes about 20 minutes, and the gas replacement is completed in 20 minutes, so that the argon content inside the protective cover is reduced to below 100ppm, so that the atmosphere in the cover reaches the required low oxygen environment. During this period, the oxygen content sensor and the digital monitoring system continue to monitor online, and the oxygen fluctuation amplitude is controlled within ±5ppm, providing a stable atmosphere environment for subsequent laser cladding and laser shock processing.

[0150] Go to step 3 to step 6 and start the laser repair equipment. Aim the laser beam at the surface of the metal pipe, control the scanning speed and power density, and heat the area to be repaired to a local molten state. Synchronously, high-temperature alloy powder is delivered through the nozzle, and after melting, it forms a metallurgical bonding layer with the base material. After each layer of cladding is completed, a laser impact device can be used to emit short-pulse high-energy lasers to form transient plasma shock waves, inducing high-amplitude residual compressive stress in the surface material, thereby improving the crack resistance and fatigue life of the cladding layer. During the repair process, the oxygen content in the cover fluctuates very little while the laser head and the impact head are working. The sensor can detect the oxygen content inside the protective cover. During the processing, the oxygen content is stable at 20ppm to 200ppm, and is always maintained within the set low oxygen concentration range to ensure that the cladding layer forms a high-quality metal bond in an oxidation-free environment.

[0151] After the repair is completed, Figure 12 As shown, a regular and uniform striped cladding layer forms on the surface of the defective area of the metal pipe. Each stripe corresponds to a laser scanning path. The cladding layer has a dense surface, free of visible pores, cracks, or inclusions. The overall cladding thickness is uniform, with a natural boundary transition. Microstructural observation reveals fine grains in the cladding layer, good metallurgical bonding, and improved overall mechanical properties.

[0152] This invention addresses the issues of inadequate protection, delayed pressure regulation, and poor sealing adaptability associated with existing gas shields for in-situ laser cladding repair of metal pipelines. By systematically optimizing the structural design, the shield's shell features top and bottom openings, with the bottom profile precisely matching the pipeline's outer wall, effectively sealing complex curved surfaces and improving airtightness. Diagonally arranged inlet and outlet ports on the shield's sidewalls optimize argon flow, reduce local oxygen concentration, and prevent oxidation and porosity during cladding. A flexible top shield and interface ensure dynamic adaptation to the laser cladding head and maintain a seal. A flexible gas storage device automatically absorbs and releases gas based on pressure fluctuations, maintaining a stable atmosphere. An internal oxygen content sensor monitors and regulates gas displacement in real time, improving response speed and control accuracy. A support fixture employs a combination of electromagnets and steel wire ropes for rapid installation and removal, preventing mechanical damage. The shield's interior is divided into cladding, processing, and gas control zones, achieving zoned protection and dynamic pressure balance. Pressure and temperature sensors and an observation window provide real-time monitoring of the working environment, ensuring cladding quality and safety. 3D modeling and flow field simulation optimize the structural layout to ensure uniform airflow and a low-oxygen environment. The overall solution significantly improves the efficiency, stability, and adaptability of the atmosphere protection during laser melting and forging repair.

[0153] The above is only an embodiment of the present invention, and common sense such as the specific structure and characteristics of the scheme are not described in detail here. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claim involved.

Claims

1. A metal pipeline laser melting and forging in-situ repair gas protection cover, characterized in that: include: A protective cover shell (5) is provided with an opening structure at its top and bottom, and a repair space is formed therein. The bottom profile of the protective cover shell (5) matches the outer surface of the metal pipe (8) to achieve sealed coverage. An air inlet (4) and an air outlet (9) are provided on the side wall of the protective cover shell (5). The air inlet (4) and the air outlet (9) are arranged along the diagonal direction of the overall structure of the protective cover shell (5) to achieve the input and discharge of protective gas. A flexible shield (12) is arranged on the top of the protective shield shell (5) and is circumferentially sealed along its edge; an interface is provided on the top of the flexible shield (12) for communicating with the working head of the laser cladding equipment to form a closed laser repair space; A flexible gas storage device (10) is arranged on the side of the protective cover shell (5), and the flexible gas storage device (10) comprises a gas storage ball (10-2), a gas storage ball interface (10-3), a valve plate, and a valve stem (10-5); one end of the gas storage ball interface (10-3) is in communication with the gas storage ball (10-2), and the other end is passed through and connected to the side wall of the protective cover shell (5) to achieve gas communication with the gas storage ball and its internal space; the valve plate is arranged inside the gas storage ball interface (10-3), one end of the valve stem (10-5) is connected to the valve plate, and the other end extends out of the gas storage ball protective shell (10-1), and the valve stem (10-5) is controlled to be opened or closed in the gas storage ball interface (10-3) by rotating the valve stem (10-5); The gas storage ball (10-2) is made of a flexible material with expandable properties and is used to automatically absorb part of the gas to buffer the pressure when the internal pressure of the protective cover shell (5) increases, or to release the stored gas to replenish the gas volume when the internal pressure decreases; An oxygen content sensor (15) is disposed inside the protective cover housing (5) and is connected to an external control system for detecting the oxygen concentration inside the protective cover housing (5) in real time. When the detected oxygen content is higher than a set threshold, the air inlet (4) and the air outlet (9) are linked to open to replace the gas inside the protective cover housing (5); A steel wire rope fixing device is arranged on the side of the protective cover shell (5).

2. The metal pipeline laser melting in-situ repair gas protection cover according to claim 1 is characterized in that: The flexible gas storage device (10) further comprises an aluminum alloy mesh (10-4); the aluminum alloy mesh (10-4) is arranged inside the gas storage ball interface (10-3).

3. The metal pipeline laser melting and forging in-situ repair gas protection cover according to claim 1 is characterized in that: The internal space of the protective cover shell (5) is divided into a melting and forging area, a processing area and a gas control area; the melting and forging area is located below the working head of the laser cladding equipment; the processing area is located outside the melting and forging area; the gas control area is located on the side of the protective cover shell (5) and is used for installing the flexible gas storage device (10).

4. The metal pipeline laser melting and forging in-situ repair gas protection cover according to claim 1 is characterized in that: It also includes a pressure sensor (16) and a temperature sensor (17), which are arranged inside the protective cover shell (5) and are used to monitor internal temperature and pressure parameters in real time.

5. The metal pipeline laser melting and forging in-situ repair gas protection cover according to claim 1 is characterized in that: The top of the flexible shield (12) is provided with two mounting interfaces, which are used for mounting a laser cladding head and a laser impact head respectively.

6. The metal pipeline laser melting and forging in-situ repair gas protection cover according to claim 1 is characterized in that: The supporting and fixing device comprises an electromagnet (7) and a steel wire rope (11); one end of the steel wire rope (11) is hingedly connected to the protective cover shell (5), and the other end is mounted with the electromagnet (7), and is used to detachably fix the protective cover shell (5) to the metal outer wall of the metal pipe (8) by magnetic attraction.

7. The metal pipeline laser melting and forging in-situ repair gas protection cover according to claim 1 is characterized in that: It also includes an observation window arranged on the side wall of the protective cover shell (5), the observation window including an embedded acrylic plate (14) and a high-temperature sealing frame; and a sealing ring is provided on the bottom edge of the protective cover shell (5).

8. A method for using a metal pipeline laser melting in-situ repair gas protection cover according to any one of claims 1 to 7, characterized in that: The method of use includes: Step 1: Align the bottom profile of the protective cover shell with the outer surface of the metal pipe so that the repair area of the metal pipe is located inside the protective cover shell. Adjust the position of the electromagnetic fixing device and start the electromagnetic fixing device so that the protective cover shell fits tightly against the outer wall of the metal pipe. Step 2: Connect the air inlet to the inert gas supply pipe, and the air outlet to the exhaust pipe or exhaust gas treatment device. Start the gas supply system and input inert gas from the air inlet to gradually fill the inside of the protective cover. At the same time, monitor the data of the oxygen content sensor to detect the oxygen concentration inside the protective cover. Step 3: If the oxygen concentration is detected to be >100ppm, the air outlet is automatically opened while the gas input at the air inlet is maintained to perform gas replacement and discharge the high-oxygen gas. After the oxygen concentration drops to ≤100ppm, the flexible gas storage device is opened and inflated until the storage ball is full. The air inlet and outlet are closed, and the feedback from the pressure sensor is observed. Step 4: Start the laser cladding equipment, select the corresponding cladding parameters, monitor the data of the pressure sensor in real time, use the temperature sensor to monitor the temperature inside the protective cover, and monitor the laser cladding process in real time through the acrylic plate; Step 5: During the repair process, the flexible gas storage device automatically adjusts according to the changes in the internal airflow. When the air pressure drops, the storage ball releases the stored gas, and when the air pressure rises, the storage ball absorbs the excess gas. The sensor detects the oxygen content inside the protective cover. During the processing, the oxygen content is stabilized at 20ppm to 200ppm. Step 6: After the repair is completed, stop the laser cladding equipment, turn off the laser cladding head and laser impact head, wait for the air pressure and temperature inside the protective cover to return to normal, turn off the electromagnetic fixing device, slowly remove the protective cover and clean the inside of the protective cover.

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