A method for repairing uneven wear on the cutterhead panel of a tunnel boring machine by welding an inverted cone anchor.

Abstract

A method for repairing uneven wear on a tunnel boring machine (TBM) cutterhead panel using inverted conical anchor welding is disclosed, applicable to wear areas with trapezoidal cross-sections. The steps are as follows: 1. Flattening the wear area: Cleaning the surface of the cutterhead base material using carbon arc gouging; 2. Layered inverted conical welding: Stacking and welding wear-resistant plates to the wear area, with each layer forming an inverted conical welding angle with the cutterhead base material to increase the fusion area and improve bonding strength; 3. Setting anchor holes: Creating anchor holes in the outermost wear-resistant plate, penetrating the outermost layer and connecting to the surface of the next wear-resistant plate; 4. Hole plugging welding: Filling the anchor holes with welding rods to form an anchoring structure similar to a metal rivet. This method, by increasing the welding fusion area through inverted conical welding and combining it with the anchoring structure, significantly improves the fatigue resistance and load-bearing capacity of the repaired structure, extends the service life of the cutterhead, and ensures the safety and continuity of TBM construction.

Description

Technical Field

[0001] This invention relates to the field of cutterhead wear repair technology, and in particular to a method for repairing uneven wear on the cutterhead panel of a tunnel boring machine by welding an inverted cone anchor. Background Technology

[0002] With continuous innovation and breakthroughs in tunnel boring machine (TBM) technology, the TBM construction method, with its numerous advantages such as high automation, fast construction speed, and minimal environmental impact, is widely used in various civil engineering projects, including urban subways, river-crossing tunnels, urban underground utility tunnels, railway tunnels, and water diversion projects. However, during TBM construction, factors such as geological conditions and imbalances in technical parameters can cause the cutterhead to malfunction, leading to wear and tear on the cutterhead itself. This can range from minor wear-resistant welded mesh wear to severe wear through the cutterhead panel, necessitating shutdown and welding repairs.

[0003] Based on the characteristics of cutterhead rotation rock cutting operations, the wear pattern of the cutterhead is basically annular grooves, and the cross-section of the worn area is trapezoidal. For repairing the worn parts of the cutterhead, the traditional method involves attaching a single layer of steel plate above the annular groove, and then fully welding the seams around the steel plate to fill the worn grooves and achieve the purpose of repairing the cutterhead. However, due to the limited effective welding area between the steel plate and the cutterhead base material, the repair quality achieved by the above method is difficult to maintain consistently over the long term. Furthermore, the edges of the cutterhead are prone to wear during construction, and under prolonged pressure and friction with the rock surface and slag, the weld seams are more likely to wear off, increasing the risk of secondary damage to the cutterhead. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for repairing uneven wear on the cutterhead panel of a tunnel boring machine (TBM) using a conical anchor welding method. This method increases the welding fusion area, enhances the interfacial bonding strength, significantly improves the reliability of the repaired structure, and ensures that the repaired cutterhead can withstand complex working loads.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for repairing uneven wear on a shield tunnel cutterhead panel using inverted conical anchor welding is provided, applicable to wear areas with trapezoidal cross-sections, characterized by the following steps:

[0006] 1) Smoothing the worn area: Use carbon arc gouging to clean the cutter head base material on the worn area of ​​the cutter head;

[0007] 2) Layered inverted cone welding: Wear-resistant plates are stacked and welded in layers onto the cutter disc base material in the wear area of ​​the cutter disc, with each layer of wear-resistant plate forming an inverted cone welding angle with the cutter disc base material;

[0008] 3) Anchor hole setting: Anchor holes are set on the outermost wear-resistant plate. The anchor holes penetrate the wear-resistant plate and connect to the surface of the adjacent upper wear-resistant plate.

[0009] 4) Hole plugging welding: Welding rods are used to fill the hole with plug welding. After filling, an anchoring structure similar to a metal rivet is formed on the anchoring hole, so that the outermost wear-resistant plate is anchored to the surface of the adjacent upper wear-resistant plate.

[0010] As a further improvement of the present invention, in step 1), a Lincoln SAE-1000D DC arc welding machine with φ8mm carbon rod is used for air gouging; the air gouging current is set to 600-800A, the compressed air pressure is 0.5-0.6MPa, and the gouging speed is 80-100mm / min; the cutter head base material on the wear area of ​​the cutter head is cleaned by segmented air gouging, and the length of each segment is ≤500mm; during the air gouging process, a water cooling device is used to cool the cutter head base material to avoid local overheating and annealing of the cutter head base material; during the air gouging process, the air gouging depth and surface quality are monitored in real time, and the equipment parameters are adjusted to ensure that the hardness change of the base surface after air gouging is ≤5%, maintaining the mechanical properties of the cutter head base material; during the air gouging process, the current and air pressure are adjusted to control the gouging depth and width, remove the oxide scale, loose structure and old welds on the cutter head base material, and ensure effective flattening of the cutter head base material.

[0011] As a further improvement of the present invention, in step 2), the wear-resistant plate is WearTuf 450 wear-resistant plate; the thickness of the wear-resistant plate is 10-30mm, and the edge of the wear-resistant plate is cut with a CNC flame cutting machine to form a 25-35° V-shaped bevel with a bevel depth of 5-8mm. The inverted conical welding angle between the wear-resistant plate and the cutter head base material is 65-75°. The welding thickness of each layer of wear-resistant plate is 5-8mm, and the welding direction of each layer of wear-resistant plate intersects the previous layer of wear-resistant plate at 90° to form a zigzag weld path to increase the bonding force between the weld layers. During welding, the root pass is first performed using CHT711 flux-cored welding wire with a penetration depth of 3-5mm to ensure a good bond between the base material and the wear-resistant plate. Then, layer-by-layer welding is performed using UTP A DUR600 wear-resistant welding wire. After each layer of wear-resistant plate is welded, it is ground to remove the oxide scale to ensure the quality of the interlayer bonding.

[0012] As a further improvement of the present invention, in step 3), the anchoring holes are symmetrically arranged at both ends of the outermost wear-resistant plate; the diameter of the anchoring holes is 40mm, the distance between the anchoring holes at both ends is 300-500mm, and each anchoring hole is 50-80mm away from the edge of the wear-resistant plate.

[0013] As a further improvement of the present invention, in step 4), Φ1.6mm welding rods are used for hole filling plug welding, and the filling is carried out in 3 times. After each filling, the hole must be cooled to room temperature before the next welding rod can be used.

[0014] As a further improvement of the present invention, in steps 2) and 4), an OTC FD-B4 dual-pulse CO2 shielded welding machine is used for welding. The gas ratio of the welding machine is 98% CO2 and 2% Ar, and the flow rate is 20-25 L / min. A gas mixer is used to ensure a uniform and stable gas supply. During welding, the welding current is 200-250 A, the voltage is 24-28 V, the welding speed is 300-400 mm / min, and the interpass temperature is controlled to be ≤150℃.

[0015] As a further improvement of the present invention, in steps 2) and 4), ventilation in the chamber needs to be strengthened during welding. Two axial flow blowers with a power of 5.5kW and an air volume of ≥1500m³ / h are used for ventilation, along with φ300mm flame-retardant air ducts. Smoke exhaust ports are evenly set at the top of the chamber and air inlets are set at the bottom to form a vertical flow field with low-level air intake and high-level air exhaust, so as to achieve directional and efficient discharge of welding fumes. A multi-channel gas detector is set up. When the harmful gas content in the chamber exceeds the standard, ventilation is increased to ensure that the air exchange rate is ≥25 times / h and the smoke and dust removal efficiency is ≥90%, so as to rapidly reduce the concentration of harmful gases and dust in the chamber.

[0016] As a further improvement of the present invention, in steps 2) and 4), temperature and humidity control is required during welding. A Monte Carlo-500 rotary dehumidifier is used, and three high-precision temperature and humidity sensors are arranged in the welding area. When the ambient humidity is > 60% RH, the dehumidifier automatically starts to control the humidity within the target range of 40% - 50% RH. Before welding, the bevel of the wear-resistant plate and the surrounding 20mm area are preheated with an oxy-acetylene flame at a temperature of 80-100℃ for 10 minutes to remove moisture and oil from the surface of the wear-resistant plate and improve the crack resistance of the weld joint. Immediately after welding, the plate is covered with 50mm thick insulation cotton and slowly cooled to room temperature to reduce welding stress. The lower limit of the welding machine current is selected to reduce the heat input of the welding machine by 10%-15%, and the CO2 gas of the welding machine is ensured to be dry and the welding wire is free of rust. The hydrogen content of the weld is controlled to ≤8ml / 100g.

[0017] The beneficial effects of this invention are as follows: In this invention, a layered inverted cone welding method is adopted, which effectively increases the welding fusion area by utilizing the three-dimensional geometric structure and improves the interface bonding strength. At the same time, the anchoring holes and welding rods are used to form an anchoring structure similar to metal rivets. Through the dual effects of metallurgical bonding and mechanical anchoring, the reliability of the repair structure is significantly improved, ensuring that the repaired cutterhead can withstand complex working loads. In particular, in response to the fatigue resistance requirements under dynamic loads in shield tunneling, the service life of the cutterhead repair structure is effectively extended, ensuring the safety and continuity of shield tunneling. Detailed Implementation

[0018] The present invention will be further described below with reference to specific embodiments.

[0019] The wear repair of the cutterhead of a tunnel boring machine (TBM) in a metro project in Panyu District, Guangzhou City, Guangdong Province, adopted the inverted cone anchor welding method for repairing uneven wear of the cutterhead panel described in this invention. The left-line tunnel section of this project was constructed using a Mitsubishi 8780 TBM. Due to sudden changes in strata and poor soil improvement, the TBM cutters and cutterhead suffered severe wear, making further excavation impossible and forcing a shutdown (excavation to ring 367, cutterhead ring 372) under the riverbank of the Pearl River Pingzhou Waterway in Panyu District (approximately 400 meters below). The TBM was buried at a depth of approximately 36.6 meters, with a water depth of 4-14 meters. The tunnel strata were mainly composed of <9-2> slightly weathered mudstone.

[0020] Inspection of the cutter head panel revealed that the entire circumference of the 44#-46# hob track area on the front spokes of the cutter head was worn, with a wear groove 350mm wide and 25mm deep; the front spokes were also worn, with a width of 350mm and a depth of 30mm; the steel plate in the outer arc corner area was worn through, with a wear width of 80mm and a thickness of 30mm; the outer circumference of the cutter head had a wear groove 300mm wide and 50mm deep, and the gauge-maintaining cutter had fallen off. This invention primarily modifies the wear groove on the outer circumference of the cutter head, giving it a trapezoidal cross-section.

[0021] The steps of a method for repairing uneven wear on the cutterhead panel of a tunnel boring machine (TBM) with inverted cone anchor welding are as follows:

[0022] 1) Smoothing the worn area: Use carbon arc gouging to clean the cutter head base material in the worn area of ​​the cutter head.

[0023] Specifically, a Lincoln SAE-1000D DC arc welding machine was used with an 8mm carbon rod for air gouging. The air gouging current was set to 600-800A, the compressed air pressure to 0.5-0.6MPa, and the gouging speed to 80-100mm / min.

[0024] The cutter head base material in the wear area of ​​the cutter head is cleaned by segmented air gouging, with each segment having a length of ≤500mm.

[0025] During air gouging, a water-cooling device is used to cool the cutter head base material to prevent local overheating and annealing.

[0026] During air gouging, it is necessary to monitor the gouging depth and surface quality in real time. By adjusting the equipment parameters, it is ensured that the hardness change of the base surface after air gouging is ≤5%, thus maintaining the mechanical properties of the cutter head base material.

[0027] During air gouging, the current and air pressure are adjusted to control the gouging depth and width, removing oxide scale, loose structure and old welds from the cutter head base material, ensuring effective flattening of the cutter head base material.

[0028] 2) Layered inverted cone welding: Wear-resistant plates are stacked and welded on the cutter disc base material in the wear area of ​​the cutter disc, and an inverted cone welding angle is formed between each layer of wear-resistant plate and the cutter disc base material.

[0029] Specifically, the wear-resistant plate is WearTuf 450 wear-resistant plate, which is a fully martensitic wear-resistant steel plate that has been quenched or quenched and tempered. It has an average Brinell hardness of 450HBW and has good wear resistance, weldability and cold forming performance.

[0030] A total of three layers of wear-resistant plates are used. The first layer of wear-resistant plate is 20mm thick, 50mm wide, and 1000mm long. The second layer of wear-resistant plate is 20mm thick, 220mm wide, and 1000mm long. The third layer of wear-resistant plate is 20mm thick, 280mm wide, and 1000mm long.

[0031] The edges of the wear-resistant plate are cut with a CNC flame cutting machine to form a 25-35° V-shaped bevel with a bevel depth of 5-8mm. The inverted conical welding angle between the wear-resistant plate and the cutter head base material is 65-75°.

[0032] The welding thickness of each wear-resistant plate is 5-8mm. The welding direction of each wear-resistant plate intersects the previous wear-resistant plate at 90° to form a zigzag weld channel to increase the bonding force between the welded layers.

[0033] During welding, the first step is to perform a root pass welding using CHT711 flux-cored welding wire, with a penetration depth of 3-5mm, to ensure a good bond between the base material and the wear-resistant plate. Then, layer-by-layer welding is performed using UTP A DUR600 wear-resistant welding wire. After each layer of wear-resistant plate is welded, it is ground to remove the oxide scale, ensuring the quality of the interlayer bonding.

[0034] 3) Anchor hole setting: Anchor holes are set on the outermost wear-resistant plate. The anchor holes penetrate the wear-resistant plate and connect to the surface of the adjacent upper wear-resistant plate.

[0035] Specifically, the anchor holes are symmetrically arranged at both ends of the outermost wear-resistant plate; the diameter of the anchor holes is 40mm, the distance between the anchor holes at both ends is 300-500mm, and each anchor hole is 50-80mm away from the edge of the wear-resistant plate.

[0036] 4) Hole plugging: Use Φ1.6mm welding rod to perform hole filling plugging on the anchoring hole. The filling is done in 3 times. After each filling, it must be cooled to room temperature before the next welding rod can be used. After the filling is completed, an anchoring structure similar to a metal rivet is formed on the anchoring hole, so that the outermost wear-resistant plate is anchored to the surface of the adjacent upper wear-resistant plate.

[0037] 5) Post-weld inspection and opening inspection: After the cutterhead is repaired, the repaired panel (outer ring beam) should be flush with the original panel (outer ring beam). Based on the cutterhead panel, measure the height and outer diameter of the worn (47#-51#) roller cutters. The repaired cutterhead panel is basically consistent with the original and meets the requirements for cutterhead excavation.

[0038] After the repair welding was completed, the project team commissioned a third-party testing unit to conduct weld flaw detection on the main beam structure of the cutter head, the cutter head panel, the spoke structure and other connecting parts, and to use a Leeb hardness tester to take three points each at the weld center, the heat-affected zone and the base material for hardness testing. The test results were all qualified, ensuring that the stability and integrity of the cutter head structure met the construction requirements.

[0039] After the tunnel boring machine (TBM) was pushed back to approximately 16m of the 377th ring, personnel were dispatched to inspect the cutterhead repair welding. No abnormalities were found in the welds, and the cutterhead was in good condition. After the tunnel was completed (approximately 1100m of tunneling), a thorough inspection of the overall cutterhead revealed that it was in good condition, with no loosening or detachment of the wear-resistant plates and no abnormal wear. This verified that the reliability of the proposed method for repairing uneven wear on the cutterhead panel using an inverted cone anchor welding technique meets the requirements.

[0040] The welding process in steps 2) and 4) above also includes the following:

[0041] The wear-resistant plate is welded using a low-hydrogen process. The entire welding process is carried out using an OTC FD-B4 dual-pulse CO2 shielded welding machine. The gas ratio of the welding machine is 98% CO2 and 2% Ar, with a flow rate of 20-25 L / min. A gas mixer is used to ensure a uniform and stable gas supply. During welding, the welding current is 200-250 A, the voltage is 24-28 V, the welding speed is 300-400 mm / min, and the interpass temperature is controlled to be ≤150℃.

[0042] Because the soil chamber is a closed space, a large amount of smoke and dust will be generated during the cutterhead repair process. Therefore, proper ventilation and smoke extraction measures are necessary during construction to enhance air exchange within the chamber. Specifically, two 5.5kW axial flow blowers with an air volume ≥1500m³ / h are used, paired with φ300mm flame-retardant ducts for ventilation. Smoke exhaust vents are evenly distributed at the top of the soil chamber, and air inlets are located at the bottom, forming a vertical airflow field with low-level intake and high-level exhaust, achieving directional and efficient removal of welding fumes. If necessary, the ball valve of the pressure-holding device can be opened to send compressed air from the air compressor into the soil chamber through the pressure-holding gas pipeline on the chamber wall to accelerate air replacement and draw the smoke out of the chamber, allowing the smoke generated by gas cutting to dissipate quickly and preventing personnel from inhaling and being harmed. A multi-channel gas detector (detection items: CO≤30ppm, O2≥19.5%, dust concentration≤10mg / m³) is installed at an appropriate location inside the earthen chamber. Data is automatically recorded every 5 minutes. When the concentration of harmful substances in the chamber exceeds the standard (CO concentration≥50ppm), the backup fan is activated, increasing the air volume by 50% to ensure an air exchange rate of ≥25 times / h and a smoke and dust removal efficiency of ≥90%, thereby rapidly reducing the concentration of harmful gases and dust in the chamber to ensure personnel safety.

[0043] Based on the welding characteristics of WearTuf 450 wear-resistant steel plate and CHT711 welding wire, the welding humidity must be strictly controlled at ≤50%RH. This must be combined with preheating, material drying, and process optimization to prevent hydrogen-induced cracking and hardness reduction. Ambient humidity must be monitored throughout the welding process. WearTuf 450 wear-resistant steel plate has a high carbon content (approximately 0.25%) and is highly sensitive to hydrogen; high humidity can easily lead to increased hydrogen content in the weld, triggering delayed cracking. Therefore, temperature and humidity control within the welding chamber is necessary. A Montel Carry-500 rotary dehumidifier was used, with three high-precision temperature and humidity sensors placed in the welding area. When the ambient humidity > 60% RH, the dehumidifier automatically started, controlling the humidity within the target range of 40% - 50% RH. Before welding, the bevel of the wear-resistant plate and the surrounding 20mm area were preheated with an oxy-acetylene flame at a temperature of 80-100℃ for 10 minutes to remove moisture and oil from the surface of the wear-resistant plate and improve the crack resistance of the weld joint. Immediately after welding, the plate was covered with 50mm thick insulation cotton and allowed to cool slowly to room temperature to reduce welding stress. The lower limit of the welding machine current was selected to reduce the heat input of the welding machine by 10% - 15%, and the CO2 gas of the welding machine was ensured to be dry and the welding wire free of rust. The hydrogen content of the weld was controlled to ≤8ml / 100g.

[0044] Compared to traditional repair welding processes, this invention effectively overcomes their shortcomings. The inverted cone anchoring welding method breaks through the limitations of traditional planar welding, utilizing a three-dimensional geometric structure to increase the effective connection area. Through the dual effects of "mechanical anchoring + metallurgical combination," the reliability of the repaired structure is significantly improved, especially addressing the fatigue resistance requirements under dynamic loads during shield tunneling, effectively extending the service life of the cutterhead repair structure and ensuring the safety and continuity of shield tunneling construction. Furthermore, this invention constructs a closed-loop control system for "ventilation, temperature and humidity, and welding parameters." Addressing the special environment of welding in confined spaces, precise control of temperature, humidity, and ventilation creates favorable environmental conditions for welding, significantly improving process stability and effectively reducing the welding defect rate.

[0045] The above-described embodiments are merely illustrative of the present invention and are not intended to limit the present invention in any way. Any person skilled in the art who makes partial modifications or alterations to the technical content disclosed in the present invention without departing from the scope of the technical features of the present invention shall still fall within the scope of the technical features of the present invention.

Claims

1. A method for repairing uneven wear on the cutterhead panel of a tunnel boring machine (TBM) using inverted conical anchor welding, applicable to wear areas with trapezoidal cross-sections, characterized in that... Includes the following steps: 1) Smoothing the worn area: Use carbon arc gouging to clean the cutter head base material on the worn area of ​​the cutter head; 2) Layered inverted cone welding: Wear-resistant plates are stacked and welded in layers onto the cutter disc base material in the wear area of ​​the cutter disc, with each layer of wear-resistant plate forming an inverted cone welding angle with the cutter disc base material; 3) Anchor hole setting: Anchor holes are set on the outermost wear-resistant plate. The anchor holes penetrate the wear-resistant plate and connect to the surface of the adjacent upper wear-resistant plate. 4) Hole plugging welding: Welding rods are used to fill the hole with plug welding. After filling, an anchoring structure is formed on the anchoring hole, so that the outermost wear-resistant plate is anchored to the surface of the adjacent upper wear-resistant plate. In step 2), WearTuf 450 wear-resistant plate is used; the thickness of the wear-resistant plate is 10-30mm, and the edges of the wear-resistant plate are cut with a CNC flame cutting machine to form a 25-35° V-shaped bevel with a bevel depth of 5-8mm. The inverted conical welding angle between the wear-resistant plate and the cutter head base material is 65-75°; the welding thickness of each layer of wear-resistant plate is 5-8mm, and the welding direction of each layer of wear-resistant plate intersects the previous layer of wear-resistant plate at 90° to form a zigzag weld path to increase the bonding force between the weld layers; during welding, the root pass is first performed using CHT711 flux-cored welding wire with a penetration depth of 3-5mm to ensure a good bond between the base material and the wear-resistant plate. Then, layer-by-layer welding is performed using UTP A DUR600 wear-resistant welding wire. After each layer of wear-resistant plate is welded, it is ground to remove the oxide scale to ensure the quality of the interlayer bonding. In step 4), Φ1.6mm welding rods are used for hole filling plug welding, which is performed in 3 stages. After each filling, the hole must be cooled to room temperature before the next welding rod can be used. In steps 2) and 4), the welding current is 200-250A, the voltage is 24-28V, the welding speed is 300-400mm / min, and the interpass temperature is controlled to be ≤150℃.

2. The method for repairing uneven wear on the cutterhead panel of a tunnel boring machine (TBM) using a conical anchor welding method according to claim 1, characterized in that: In step 1), a Lincoln SAE-1000D DC arc welding machine with an 8mm carbon rod is used for air gouging. The air gouging current is set to 600-800A, the compressed air pressure to 0.5-0.6MPa, and the gouging speed to 80-100mm / min. The cutter head base material in the wear area is cleaned using a segmented air gouging method, with each segment ≤500mm in length. During the air gouging process, a water-cooling device is used to cool the cutter head base material to prevent local overheating and annealing. During the air gouging process, the gouging depth and surface quality are monitored in real time. By adjusting the equipment parameters, the hardness change of the base surface after air gouging is ensured to be ≤5%, maintaining the mechanical properties of the cutter head base material. During the air gouging process, the current and air pressure are adjusted to control the gouging depth and width, removing oxide scale, loose structure, and old welds from the cutter head base material to ensure effective flattening of the cutter head base material.

3. The method for repairing uneven wear on the cutterhead panel of a tunnel boring machine (TBM) using a conical anchor welding method according to claim 1, characterized in that: In step 3), the anchor holes are symmetrically set at both ends of the outermost wear-resistant plate; the diameter of the anchor holes is 40mm, the distance between the anchor holes at both ends is 300-500mm, and each anchor hole is 50-80mm away from the edge of the wear-resistant plate.

4. The method for repairing uneven wear on the cutterhead panel of a tunnel boring machine (TBM) using a conical anchor welding method according to claim 1, characterized in that: In steps 2) and 4), ventilation inside the chamber needs to be strengthened during welding. Two axial flow blowers with a power of 5.5kW and an air volume of ≥1500m³ / h are used for ventilation, along with φ300mm flame-retardant air ducts. Smoke exhaust vents are evenly set at the top of the chamber, and air inlets are set at the bottom to form a vertical flow field with low-level air intake and high-level air exhaust, so as to achieve directional and efficient discharge of welding fumes. A multi-channel gas detector is set up. When the harmful gas content in the chamber exceeds the standard, ventilation is increased to ensure that the air exchange rate is ≥25 times / h and the smoke and dust removal efficiency is ≥90%, so as to rapidly reduce the concentration of harmful gases and dust in the chamber.

5. The method for repairing uneven wear on the cutterhead panel of a tunnel boring machine (TBM) using a conical anchor welding method according to claim 1, characterized in that: In steps 2) and 4), temperature and humidity control is required during welding. A Monte Carlo-500 rotary dehumidifier is used, and three high-precision temperature and humidity sensors are placed in the welding area. When the ambient humidity is > 60% RH, the dehumidifier automatically starts to control the humidity within the target range of 40% - 50% RH. Before welding, the bevel of the wear-resistant plate and the surrounding 20mm area are preheated with an oxy-acetylene flame at a temperature of 80-100℃ for 10 minutes to remove moisture and oil from the surface of the wear-resistant plate and improve the crack resistance of the weld joint. Immediately after welding, cover with 50mm thick insulation cotton and slowly cool to room temperature to reduce welding stress. Select the lower limit of the welding machine current and reduce the heat input of the welding machine by 10% - 15% to control the hydrogen content of the weld to ≤8ml / 100g.