Inverted cone anchoring welding method for repairing uneven abrasion of shield cutter head panel

Abstract

An inverted cone anchoring welding method for repairing uneven abrasion of a shield cutter head panel is suitable for a trapezoid section abrasion area and comprises the following steps that the abrasion area is leveled, and the surface of cutter head base metal is cleaned through carbon arc air gouging; the abrasion-resistant plates are welded to the abrasion area in a layered and stacked mode, an inverted-cone-shaped welding included angle is formed between each layer of abrasion-resistant plate and the cutterhead base material, the fusion area is increased, and the bonding strength is improved; anchoring holes are formed in the outermost wear-resisting plate, and the anchoring holes penetrate through the outermost wear-resisting plate and communicate with the surface of the lower wear-resisting plate; and plug welding in the hole: filling the anchoring hole with a welding rod, and forming an anchoring structure similar to a metal rivet on the anchoring hole. According to the method, the welding fusion area is increased through back taper welding, and the anchoring structure is combined, so that the fatigue resistance and the bearing capacity of the repairing structure are remarkably improved, the service life of the cutterhead is prolonged, and the safety and continuity of shield construction are guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of cutter head wear repair, and particularly to a reverse cone anchoring welding method for repairing uneven wear of a shield cutter head panel. Background Art

[0002] With the continuous innovation and breakthrough of shield industrial technology, the shield tunneling method construction mode with many advantages such as high automation degree, fast construction speed, and small environmental impact is widely used in various civil engineering projects, including urban subways, cross-river tunnels, urban underground utility tunnels, railway tunnels, water diversion projects, etc. When the shield construction is affected by factors such as geology and imbalance of technical parameter matching, once the gauge cutter loses its function, the cutter head is extremely prone to wear. In the light case, the wear-resistant welding grid is polished, and in the heavy case, the cutter head panel is worn through, and it is necessary to stop the machine for welding repair.

[0003] According to the working characteristics of the cutter head rotating to cut rock, the wear form of the cutter head is basically an annular groove, and the cross-section of the wear area is trapezoidal. For the repair of the worn part of the cutter head, the traditional method is to stick a single-layer steel plate above the annular groove, and then fully weld the joints around the steel plate to fill the worn groove to achieve the purpose of repairing the cutter head. Due to the limited effective welding area between the steel plate and the cutter head base material, the repair quality achieved by using the above method is difficult to be long-term stable, and the edge of the cutter head is prone to wear during construction. Under the long-term extrusion and friction with the rock surface and slag, the weld part is more prone to wear and fall off, increasing the risk of secondary damage to the cutter head. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a reverse cone anchoring welding method for repairing uneven wear of a shield cutter head panel. By this method, the welding fusion area is increased, the interface bonding strength is improved, the reliability of the repair structure is significantly improved, and it is ensured that the repaired cutter head can withstand complex working loads.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A reverse cone anchoring welding method for repairing uneven wear of a shield cutter head panel is provided, which is applicable to a wear area with a trapezoidal cross-section, and is characterized by including the following steps:

[0006] 1) Smoothing the wear area: Using carbon arc air gouging to clean the cutter head base material on the cutter head wear area;

[0007] 2) Layered reverse cone welding: The wear-resistant plates are stacked and welded layer by layer on the cutter head base material in the cutter head wear area, and an inverted conical welding angle is formed between each layer of wear-resistant plate and the cutter head base material;

[0008] 3) Setting of anchoring holes: Anchoring holes are set on the outermost layer of wear-resistant plates, and the anchoring holes penetrate through this layer of wear-resistant plates and communicate with the surface of the adjacent upper layer of wear-resistant plates;

[0009] 4) Plug welding in holes: Use electrodes to perform plug welding for filling in the anchoring holes. After filling, an anchoring structure similar to a metal rivet is formed on the anchoring holes, so that the outermost wear-resistant plate is anchored on 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 welder is used with a φ8mm carbon rod for air gouging operation; the air gouging current is set at 600 - 800A, the compressed air pressure is 0.5 - 0.6MPa, and the gouging speed is 80 - 100mm / min; the segmented air gouging method is used to clean the cutter head base material in the cutter head wear area, 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 annealing of the cutter head base material caused by local overheating; during the air gouging process, the air gouging depth and surface quality are monitored in real time, and by adjusting the equipment parameters, it is ensured 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, by adjusting the current and air pressure, the gouging depth and width are controlled to remove the oxide scale, loose tissue and old weld seams on the cutter head base material, ensuring effective leveling treatment of the cutter head base material.

[0011] As a further improvement of the present invention, in step 2), WearTuf 450 wear-resistant plates are used; the thickness of the wear-resistant plates is 10 - 30mm, and the edges of the wear-resistant plates are The numerical control flame cutting machine cuts to form 25 ~35° V-shaped grooves with a groove depth of 5 - 8mm, and 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 with the upper layer of wear-resistant plate at 90°, forming a zigzag weld bead to increase the bonding force between welding layers; during welding, first perform backing welding, and the backing welding is carried out using CHT711 flux-cored wire with a penetration depth of 3 - 5mm to ensure good bonding between the base material and the wear-resistant plate, and then perform layered surfacing. The layered surfacing is carried out using UTP A DUR600 wear-resistant wire for welding. After each layer of wear-resistant plate is welded, it is polished to remove the oxide scale to ensure the interlayer bonding quality.

[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 the distance from each anchoring hole to the edge of the wear-resistant plate is 50 - 80mm.

[0013] As a further improvement of the present invention, in step 4), a Φ1.6mm electrode is used for plug welding in the holes, and the filling is carried out in 3 times. After each filling, it is necessary to cool to room temperature before filling the next electrode.

[0014] 6. A method for repairing uneven wear of the shield cutter head panel by reverse taper anchor welding according to claim 1, characterized in that: in steps 2) and 4), an OTC FD-B4 double-pulse CO2 shielded welding machine is used for welding. The gas ratio of the welding machine is CO2 98% and Ar 2%, and the flow rate is 20-25 L / min. A gas mixer is used to ensure 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 interlayer temperature is controlled ≤150 °C.

[0015] As a further improvement of the present invention, in steps 2) and 4), ventilation and air change in the chamber need to be strengthened during welding. Two axial flow blowers with a power of 5.5 kW and an air volume ≥1500 m 3 / h are used for ventilation, and are paired with a φ300 mm flame-retardant air duct. Smoke exhaust ports are evenly arranged at the top of the soil chamber, and air inlets are arranged at the bottom to form a vertical flow field with low-position air inlet and high-position air exhaust, so as to achieve directional and efficient discharge of welding fumes; a multi-channel gas detector is set. When the harmful substances in the chamber exceed the standard, ventilation is increased to ensure that the air change rate ≥25 times / h and the smoke removal efficiency ≥90%, so that the concentration of harmful gases and dust in the chamber is rapidly reduced.

[0016] As a further improvement of the present invention, in steps 2) and 4), temperature and humidity control in the chamber need to be carried out during welding. A Monty Carry-500 rotary dehumidifier is used. Three high-precision temperature and humidity sensors are arranged in the welding area. When the ambient humidity >60% RH, the dehumidifier is automatically started to control the humidity within the target range of 40%-50% RH; before welding, the groove of the wear-resistant plate and the surrounding 20 mm range are preheated by oxyacetylene flame, the temperature is controlled at 80-100 °C, and it lasts for 10 min to remove the moisture and oil on the surface of the wear-resistant plate and improve the crack resistance of the welded joint; immediately after welding, cover it with 50 mm thick heat-insulating cotton and slowly cool it to room temperature to reduce welding stress; select the lower limit of the welding machine current, reduce the heat input of the welding machine by 10%-15%, and ensure that the CO2 gas of the welding machine is dry and the welding wire is not rusted, and control the hydrogen content of the weld ≤8 ml / 100 g.

[0017] The beneficial effects of the present invention are as follows: In the present invention, the method of layered reverse taper welding is adopted, and the three-dimensional geometric structure is used to effectively increase the welding fusion area and improve the interface bonding strength. At the same time, an anchoring structure similar to a metal rivet is formed by using the anchoring holes and electrodes. Through the dual effects of metallurgical bonding and mechanical anchoring, the reliability of the repair structure is significantly improved, ensuring that the repaired cutter head can withstand complex working loads, especially for the anti-fatigue requirements under dynamic loads during shield construction, effectively extending the service life of the cutter head repair structure, and ensuring the safety and continuity of shield construction. Detailed implementation mode

[0018] The present invention will be further described below in conjunction with specific embodiments.

[0019] For the repair of the cutter head wear of a shield machine in a subway project in Panyu District, Guangzhou City, Guangdong Province, a reverse taper anchor welding method for repairing uneven wear of the shield cutter head panel described in the present invention was adopted. In the left-line shield section of this project, a Mitsubishi 8780 shield machine was used for construction. Due to construction impacts such as sudden changes in the formation and poor muck improvement, the cutter tools and cutter head of the shield machine were severely worn, resulting in the inability to continue tunneling and being forced to stop (tunneling to the 367th ring, cutter head at the 372nd ring) under the river embankment of the Pearl River Pingzhou Waterway in Panyu District (underpassing about 400 meters). The overburden of the shield was about 36.6 m, the water depth was 4 - 14 m, and the strata of the tunnel body were mainly the slightly weathered layer of <9-2> mudstone.

[0020] By inspecting the wear condition of the cutter head panel, the entire circle of the 44# - 46# hob track area on the front of the cutter head was worn, with the wear groove width of 350 m and depth of 25 mm; the front spokes were worn with a width of 350 mm and depth of 30 mm; the steel plate in the outer circular arc angle area was worn through, with the wear amount of width 80 mm and thickness 30 mm; the wear groove of the outer ring of the cutter head had a width of 300 mm and depth of 50 mm, and the full-diameter cutter had fallen off. The present invention mainly modifies the wear groove of the outer ring of the cutter head, and the cross-section of this wear groove is a trapezoidal cross-section.

[0021] The steps of a reverse taper anchor welding method for repairing uneven wear of the shield cutter head panel are as follows:

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

[0023] Specifically, a Lincoln SAE-1000D DC arc welder is used with a φ8 mm carbon rod for air gouging operation. The air gouging current is set at 600 - 800 A, the compressed air pressure is 0.5 - 0.6 MPa, and the gouging speed is 80 - 100 mm / min.

[0024] The carbon arc air gouging method is adopted to clean the cutter head base material in the worn area of the cutter head, and the length of each section ≤ 500 mm.

[0025] During the air gouging process, a water cooling device is used to cool the cutter head base material to avoid annealing of the cutter head base material caused by local overheating.

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

[0027] During the air gouging process, by adjusting the current and air pressure, control the gouging depth and width, remove the oxide scale, loose tissue and old welds on the cutter head base material, and ensure effective leveling treatment of the cutter head base material.

[0028] 2) Layered inverted cone welding: The wear-resistant plates are stacked and welded layer by layer on the cutter head base material in the worn area of the cutter head. An inverted cone welding angle is formed between each layer of wear-resistant plate and the cutter head base material.

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

[0030] A total of three layers of wear-resistant plates are used. The first layer of wear-resistant plate has a thickness of 20 mm, a width of 50 mm, and a length of 1000 mm. The second layer of wear-resistant plate has a thickness of 20 mm, a width of 220 mm, and a length of 1000 mm. The third layer of wear-resistant plate has a thickness of 20 mm, a width of 280 mm, and a length of 1000 mm.

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

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

[0033] During welding, first carry out backing welding. The backing welding is carried out using CHT711 flux-cored wire with a penetration depth of 3 - 5 mm to ensure good bonding between the base material and the wear-resistant plate. Then carry out layered surfacing. The layered surfacing is carried out using UTP A DUR600 wear-resistant wire. After each layer of wear-resistant plate is welded, it is polished to remove the oxide scale to ensure the bonding quality between layers.

[0034] 3) Anchor hole setting: Anchor holes are set on the outermost layer of wear-resistant plates. The anchor holes penetrate through this layer of wear-resistant plate and communicate with the surface of the adjacent upper layer of wear-resistant plate.

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

[0036] 4) Plug welding in holes: Use a Φ1.6 mm electrode to carry out plug welding filling in the anchor holes. The filling is carried out in 3 times. After each filling, it is necessary to cool to room temperature before filling the next electrode. After filling is completed, an anchor structure similar to a metal rivet is formed on the anchor hole, so that the outermost layer of wear-resistant plate is anchored on the surface of the adjacent upper layer of wear-resistant plate.

[0037] 5) Post-welding inspection and opening inspection: After the cutter disc is repaired, in principle, the repaired panel (outer ring beam) is flush with the original panel (outer ring beam). Based on the cutter disc panel as a reference, the height and outer diameter of the worn (47#-51#) hob are measured. The repaired cutter disc panel is basically the same as the original one, meeting the cutter disc excavation requirements.

[0038] After the repair and welding was completed, the project department commissioned a third-party testing unit to conduct weld flaw detection on the cutter head main beam structure, cutter head panel, spoke structure and other connection parts, and used a Leeb hardness tester to perform hardness tests at 3 points each in the weld center, heat-affected zone, and parent material. The test results were all qualified, ensuring that the stability and integrity of the cutter head structure met the construction requirements.

[0039] After the shield was pushed to the 377th ring, about 16 meters, personnel were arranged to enter the warehouse to check the cutterhead repair welding adaptation. No abnormal welds were found, and the cutterhead was in good condition. After the tunnel was completed (about 1100 meters were excavated), the overall condition of the cutterhead was carefully checked. The cutterhead was in good condition, the wear-resistant plate did not loosen or fall off, and no abnormal wear was found, which verified that the reliability of the inverted cone anchor welding method for repairing uneven wear of the shield cutterhead panel meets the requirements.

[0040] In the welding process of the above steps 2) and 4), the following contents are also included:

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

[0042] Since the soil bin is a confined space, a large amount of smoke and dust will be generated during the repair of the cutterhead. During the construction process, ventilation and smoke exhaust measures need to be taken to strengthen ventilation in the bin. Specifically, two 5.5kW power and air volume ≥1500m 3 / h axial flow blower and φ300mm flame-retardant air duct are used for ventilation, and smoke exhaust ports are evenly arranged on the top of the soil bin and air inlets are set at the bottom to form a vertical flow field with low-level air inlet and high-level air exhaust, so as to achieve directional and efficient discharge of welding smoke. If necessary, the air pipe ball valve of the pressure-maintaining device can also be opened, and the compressed gas of the air compressor can be sent into the soil bin through the pressure-maintaining gas pipeline on the bin wall to accelerate air replacement, and the smoke in the soil bin can be drawn out, so that the smoke generated by gas cutting can be quickly dispersed to avoid injuries caused by inhalation. Multi-channel gas detectors are installed at appropriate locations in the soil bin (detection items: CO ≤ 30ppm, O ≥ 19.5%, dust concentration ≤ 10mg / m 3), automatically records data every 5 minutes. When the harmful gas in the warehouse exceeds the standard (CO concentration ≥ 50ppm), the backup fan will be started, and the air volume will be increased by 50%, ensuring that the ventilation frequency is ≥ 25 times / h and the smoke removal efficiency is ≥ 90%, so that the concentration of harmful gases and dust in the warehouse will be rapidly reduced to ensure the safety of personnel.

[0043] According to the welding characteristics of WearTuf 450 wear-resistant plate and CHT711 welding wire, the welding humidity must be strictly controlled at ≤50% RH, and preheating, material drying and process optimization must be combined to prevent hydrogen-induced cracking and hardness reduction. The ambient humidity is monitored throughout the welding process. WearTuf 450 wear-resistant plate has a high carbon content (about 0.25%) and is highly sensitive to hydrogen. High humidity can easily increase the hydrogen content of the weld and cause delayed cracking. Therefore, temperature and humidity control in the warehouse is required during welding. A Monte Carry-500 rotary dehumidifier was used, and three high-precision temperature and humidity sensors were arranged in the welding area. When the ambient humidity was >60% RH, the dehumidifier started automatically to control the humidity within the target range of 40%-50% RH. Before welding, the groove of the wear-resistant plate and the surrounding 20mm range were preheated with oxyacetylene flame, and the temperature was controlled at 80-100℃ for 10 minutes to remove moisture and oil on the surface of the wear-resistant plate and improve the crack resistance of the welded joint. After welding, 50mm thick insulation cotton was immediately covered and slowly cooled 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 CO gas of the welding machine was ensured to be dry and the welding wire was free of rust, and the hydrogen content of the weld was controlled to ≤8ml / 100g.

[0044] Compared with the traditional repair welding process, the present invention can effectively overcome the shortcomings of the traditional repair welding process. The inverted cone anchor welding method breaks through the limitations of traditional plane welding and uses a three-dimensional geometric structure to increase the effective connection area. Through the dual effects of "mechanical anchoring + metallurgical bonding", the reliability of the repair structure is significantly improved, especially for the anti-fatigue requirements under dynamic loads in shield construction, effectively extending the service life of the cutter repair structure and ensuring the safety and continuity of shield construction. In addition, the present invention also constructs a "ventilation, temperature and humidity, welding parameters" closed-loop control system. Aiming at the special environment of welding in a confined space, by accurately controlling the temperature and humidity in the warehouse and ventilation and smoke exhaust, it creates good environmental conditions for welding construction, achieves a significant improvement in process stability, and effectively reduces the welding defect rate.

[0045] The above embodiments are only used to illustrate the present invention and are not intended to limit the present invention in any form. Any person with ordinary knowledge in the technical field may make partial changes or modifications to the technical contents disclosed in the present invention without departing from the scope of the technical features of the present invention, and the equivalent embodiments without departing from the technical features of the present invention are still within the scope of the technical features of the present invention.

Claims

1. A repair method of inverted cone anchoring welding for uneven wear of the shield cutter head panel, applicable to the worn area with a trapezoidal cross-section, characterized in that It includes the following steps: 1) Wearing area leveling: Using carbon arc air gouging to clean the cutter head base material on the wearing area of the cutter head; 2) Layered inverted cone welding: Wear-resistant plates are stacked and welded layer by layer on the cutter head base material in the wearing area of the cutter head, and an inverted cone welding angle is formed between each layer of wear-resistant plate and the cutter head base material; 3) Anchor hole setting: Anchor holes are set on the outermost layer of wear-resistant plates, and the anchor holes penetrate through this layer of wear-resistant plates and communicate with the surface of the adjacent upper layer of wear-resistant plates; 4) Plug welding in holes: Using welding rods to carry out plug welding filling in the anchor holes. After filling, an anchor structure similar to a metal rivet is formed on the anchor holes, so that the outermost layer of wear-resistant plates is anchored on the surface of the adjacent upper layer of wear-resistant plates.

2. A method for repairing uneven wear of the shield cutter head panel by reverse taper anchor welding according to claim 1, characterized in that: In step 1), a Lincoln SAE-1000D DC arc welding machine is used with a φ8mm carbon rod for air gouging operation; the air gouging current is set at 600 - 800A, the compressed air pressure is 0.5 - 0.6MPa, and the gouging speed is 80 - 100mm / min; the segmented air gouging method is adopted to clean the cutter head base material on the wearing area of the cutter head, 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 annealing of the cutter head base material caused by local overheating; during the air gouging process, the air gouging depth and surface quality are monitored in real time, and by adjusting the equipment parameters, it is ensured 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, by adjusting the current and air pressure, the gouging depth and width are controlled to remove the oxide scale, loose tissue and old welds on the cutter head base material, ensuring effective leveling treatment of the cutter head base material.

3. A method for repairing uneven wear of a shield cutter head panel by reverse taper anchor welding, according to claim 1, characterized in that: In step 2), WearTuf 450 wear-resistant plate is adopted; the thickness of the wear-resistant plate is 10 - 30 mm, and the edge of the wear-resistant plate adopts Cut with a numerical control flame cutting machine to form 25 a V-groove with an angle of ~35°, the groove depth is 5 - 8 mm, and 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 - 8 mm, and the welding direction of each layer of wear-resistant plate intersects with the previous layer of wear-resistant plate at 90°, forming a zigzag weld bead to increase the bonding force between welding layers; during welding, first carry out backing welding, and the backing welding is carried out with CHT711 flux-cored wire, with a penetration depth of 3 - 5 mm to ensure good bonding between the base material and the wear-resistant plate, and then carry out multi-layer surfacing. The multi-layer surfacing is carried out with UTP A DUR600 wear-resistant wire. After welding each layer of wear-resistant plate, grind to remove the oxide scale to ensure the bonding quality between layers.

4. A method for repairing uneven wear of a shield cutter head panel by reverse taper anchoring welding, according to claim 1, characterized in that: In step 3), the anchor holes are symmetrically set at both ends of the outermost layer of wear-resistant plates respectively; the diameter of the anchor holes is 40mm, the distance between the anchor holes at both ends is 300 - 500mm, and the distance from each anchor hole to the edge of the wear-resistant plate is 50 - 80mm.

5. A method for repairing uneven wear of a shield cutter head panel by reverse taper anchor welding, according to claim 1, characterized in that: In step 4), a Φ1.6mm welding rod is used for plug welding filling in the holes, and the filling is carried out in 3 times. After each filling, it is necessary to cool to room temperature before filling the next welding rod.

6. A method for repairing uneven wear of the shield cutter head panel by reverse taper anchoring welding, according to claim 1, characterized in that: In steps 2) and 4), an OTC FD-B4 double-pulse CO shielding welding machine is used for welding. The gas ratio of the welding machine is CO 98% and Ar 2%, and the flow rate is 20 - 25L / min. The gas mixer is used to ensure uniform and stable gas supply; during welding, the welding current is 200 - 250A, the voltage is 24 - 28V, the welding speed is 300 - 400mm / min, and the interlayer temperature is controlled ≤150℃.

7. A method for repairing uneven wear of a shield cutter head panel by reverse taper anchoring welding, as claimed in claim 1, wherein: In Step 2) and Step 4), during welding, it is necessary to strengthen the ventilation and air exchange in the silo. Two axial flow blowers with a power of 5.5 kW and an air volume of ≥ 1500 m 3 / h are used for ventilation in combination with a φ300 mm flame-retardant air duct. Smoke exhaust ports are evenly arranged at the top of the soil bin, and air inlets are arranged at the bottom to form a vertical flow field with low-position air intake and high-position air exhaust, so as to achieve the directional and efficient discharge of welding fumes. A multi-channel gas detector is set. When the harmful substances in the silo exceed the standard, the ventilation is increased to ensure that the air change rate is ≥ 25 times / h and the dust removal efficiency is ≥ 90%, so as to rapidly reduce the concentration of harmful gases and dust in the silo.

8. A method for repairing uneven wear of the shield cutter head panel by reverse taper anchoring welding, according to claim 1, characterized in that: In steps 2) and 4), during welding, it is necessary to control the temperature and humidity inside the chamber. A Mont Carry-500 rotary dehumidifier is used, and three high-precision temperature and humidity sensors are arranged in the welding area. When the ambient humidity > 60%RH, the dehumidifier will automatically start and control the humidity within the target range of 40%-50%RH. Before welding, the groove of the wear-resistant plate and the area within 20 mm around it are preheated with oxyacetylene flame, and the temperature is controlled at 80-100°C for 10 minutes to remove the moisture and oil on the surface of the wear-resistant plate and improve the crack resistance of the welded joint. Immediately after welding, cover it with 50 mm thick heat-insulating cotton and slowly cool it to room temperature to reduce the welding stress. Select the lower limit of the welding machine current, reduce the heat input of the welding machine by 10%-15%, and ensure that the CO gas of the welding machine is dry and the welding wire is not rusted, and control the hydrogen content in the weld ≤ 8 ml / 100 g.