Welding construction method for water storage pipeline crawling welding robot of pumped storage power station

Abstract

The invention provides a welding construction method for a water storage pipeline crawling welding robot of a pumped storage power station, and belongs to the technical field of pipeline welding. In the method, the front face of a welding seam is bottomed through a manual welding rod, and the robot carries MAG welding for filling and covering; back gouging is conducted on the back face of the weld joint through carbon arc air gouging, and cover faces are filled with manual welding rods; when the robot carries out MAG welding, mixed gas containing 80% of Ar and 20% of CO2 is adopted as protective gas. In the pipeline welding process, the crawling robot is used for replacing manual welding, the labor intensity of welding operators is reduced, the welding automation degree is improved, and then the welding quality is comprehensively improved. The method is suitable for welding operation of crawling welding robots in large-diameter pipeline tunnels of the same type in various pumped storage power stations and other hydropower industries, including upper inclined shafts, lower inclined shafts and 5G and 6G positions of water delivery pipelines of the pumped storage power stations, and has outstanding technical advantages and remarkable economic benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of pipeline welding, and in particular relates to a welding construction method of a crawling welding robot for a water storage pipeline of a pumped storage power station. Background Art

[0002] The welding of pressure steel pipes in the water delivery system during power station construction is an important part of the installation and construction work. Taking a pumped storage power station under construction as an example, the water delivery system covers the upper reservoir inlet / outlet, water diversion upper horizontal tunnel, water diversion upper inclined shaft, water diversion middle horizontal tunnel, water diversion lower inclined shaft, water diversion lower horizontal tunnel, water diversion steel bifurcated pipe, water diversion steel branch pipe, tailwater branch pipe, tailwater bifurcated pipe, tailwater tunnel, tailwater surge chamber, lower reservoir inlet / outlet, etc. The total length of the water delivery system between the upper and lower reservoir inlets / outlets is about 2100.3m, of which the water diversion system is about 1171.4m long and the tailwater system is about 928.9m long. The various pipes here are made of Q345R, 600MPa and 800MPa high-strength steel.

[0003] At present, the automatic welding of pressure steel pipes has been realized in steel pipe processing plants, but when installed in tunnels, the main method is still manual welding (MAG or manual welding). Due to the narrow construction site in the tunnel and the difficulty of construction, the vertical welding and overhead welding of the butt girth weld require a high level of technical proficiency and it is difficult to ensure its quality. At the same time, a large amount of smoke and dust will be generated during the welding process, polluting the site and causing great harm to the workers. In response to this problem, welding robots dedicated to specific working conditions have been increasingly widely used in recent years. Although relatively mature welding robot products are available for sale, it is still a technical issue that needs to be explored to determine what welding process can achieve the best welding effect in actual working conditions such as the water storage pipeline of a pumped storage power station. Summary of the invention

[0004] The technical problem to be solved by the present invention is: when a crawling welding robot is used to weld a water storage pipeline of a pumped storage power station, how to match the process conditions to achieve the optimal welding effect.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0006] A welding construction method for a water storage pipeline of a pumped storage power station using a crawling welding robot, in which a manual electrode is used for base coating on the front side of the weld, and the robot is equipped with MAG welding for filling and covering; a carbon arc air planer is used for root cleaning on the back side of the weld, and the manual electrode is used for filling and covering; when the robot performs MAG welding, a mixed gas containing 80% Ar and 20% CO2 is used as the shielding gas.

[0007] Preferably, for welding at the 5G position, when the base material is Q345R and the base material thickness is 24 mm, the welding method of the first welding layer is SMAW, and the welding current is 150-160 A, and the welding method of the second welding layer is FCAW, and the welding current is 210-220 A, the welding voltage is 20-21 V, and the welding speed is 140-150 mm / min; the welding method of the first welding layer on the reverse side is SMAW, and the welding current is 165-180 A.

[0008] Preferably, for welding at the 6G position, when the base material is Q345R and the base material thickness is 24 mm, the welding method of the first welding level is SMAW, and the welding current is 150-160 A, the welding method of the second welding level is FCAW, and the welding current is 190-210 A, the welding voltage is 20-21 V, and the welding speed is 140-150 mm / min, the welding method of the third welding level is FCAW, and the welding current is 220-230 A, the welding voltage is 20-21 V, and the welding speed is 300-330 mm / min, and the welding method of the first welding level on the reverse side is SMAW, and the welding current is 165-180 A.

[0009] Preferably, groove prefabrication and groove assembly are performed before welding, wherein the pipe segment ring weld installed in the hole adopts flux-cored wire gas shielded welding process, the groove processing angle of 20≤δ<32mm steel plate is 50~60°, the blunt edge is 0-1mm, the butt gap is 4-8mm, the misalignment is ≤2mm, a V-shaped groove is opened, a ceramic liner is installed, single-sided welding and double-sided forming are combined with a back seam air planing root cleaning process, otherwise, manual primer robot filling and capping are used for welding; 32≤δ≤40mm all adopt an asymmetric double-sided V-shaped groove, the groove gap is 1-2mm, and the blunt edge is 1-2mm; the positive seam groove angle is 50°, the depth is 2 / 3 of the test plate thickness, the back seam groove angle is 70°, the depth is 1 / 3 of the test plate thickness, a ceramic liner is installed, single-sided welding and double-sided forming are combined with a back seam air planing root cleaning process.

[0010] Preferably, the robot is arranged and fixed before welding, wherein two robots are configured for each weld circle, a power regulator is placed on the welding platform, and auxiliary equipment of the robot is fixed on the welding platform; the entire weld circle is divided into sections, and the two robots are arranged symmetrically.

[0011] Preferably, windproof measures are arranged before welding, and the windproof measures include setting up a windproof curtain. When the windproof curtain cannot be set up, the wind speed is detected, and when the wind speed is between 2 and 4 m / s, a windshield is set on the robot.

[0012] Preferably, before welding, clean the scale, rust, slag, oil stains, and water marks within the groove and within 20 mm on both sides of the weld groove, and check the assembly dimensions, groove dimensions, and positioning weld quality; remove cracks, pores, and slag inclusions on the positioning weld.

[0013] Preferably, the humidity of the underground environment is measured before welding. When the relative humidity is greater than 80%, flame heating, electric heating or medium frequency heating are used to heat both sides of the weld to remove water vapor. After heating, a wire brush is used to clean the oil and rust within 50 mm on both sides of the groove and the edge of the groove, and polish it to a metallic luster. In the process of heating the weld, the width of the heating zone is 3 times the plate thickness on both sides of the welding center line, and not less than 100 mm. The temperature is measured using an infrared thermometer, and symmetrically at 50 mm from the center line of the weld. The distance between the measuring points of each weld is not more than 2 m, and there are no less than 3 points. During the welding process, the interlayer temperature is controlled to be not lower than the preheating temperature, and not more than 200 ° C.

[0014] Preferably, the following steps are performed in sequence before welding:

[0015] 1) Grind the tack weld parts and grind the two ends of the tack weld into a slope transition; if defects are found in the tack weld during the grinding process, remove the defects or add tack welds or re-tack welds;

[0016] 2) Clean the back of the weld, paste the ceramic liner, and check that the center of the liner is consistent with the center of the weld; re-paste the liner when the following conditions occur: baking and dehumidification are performed after the liner is pasted; cleaning the groove exceeds a certain area after the liner is pasted; no welding is performed for more than 4 hours after the liner is pasted;

[0017] When the assembly gap cannot meet the robot welding requirements, use manual welding rods to prime and the robot to fill the cover surface; use carbon arc air planer to clean the root on the back, polish to a metallic luster, and then fill the cover surface with manual welding rods;

[0018] 3) Check the appearance of the welding wire to ensure there are no water stains or rust;

[0019] 4) Check the type of protective gas, adjust the protective gas flow rate to 20-30L / min, and the gas inspection time should not be less than 30s;

[0020] 5) Arc welding.

[0021] Preferably, during the arc welding process: the arc starting points and arc ending points of the circumferential weld are staggered at intervals of not less than 30 mm; during multi-layer and multi-pass welding, the welding gun angle of the first weld of each layer is tilted downward by 10°, the welding gun angle of the last weld is tilted upward by 10°, and the welding guns of other layers are vertical; when the base weld passes through the tack weld, the welding speed is increased in advance, the arc is stopped, and the arc is restarted at the end of the tack weld; for the downslope, for each layer of weld, the swing amplitude of the first weld is controlled to be ≤2 mm; for the upslope, for each layer of weld, when welding the last weld, the upper dwell time is increased from 0.2s to 0.4s.

[0022] The core of the present invention is to use a trackless welding robot equipped with a MAG welding method, and select a mixed gas (80% Ar + 20% CO2) as a shielding gas to weld the pumped storage water pipeline. The adopted process parameters and technical measures have been rigorously verified by experiments. The present invention uses a crawling robot to replace manual welding during the pipeline welding process, which reduces the labor intensity of welding operators, improves the degree of welding automation, and thus comprehensively improves the welding quality, bringing significant benefits to the construction of pumped storage power stations.

[0023] The present invention is applicable to the welding operation of crawling welding robots in large-diameter pipeline tunnels of various pumped-storage power stations and other hydropower industries, including the 5G and 6G positions of the upper inclined shaft, lower inclined shaft and flat tunnel of the water pipeline of the pumped-storage power station. It can also be expanded to welding operations in similar scenarios in the fields of pressure vessels, shipbuilding, rail transportation, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a construction process flow chart of the present invention.

[0025] Figure 2 It is a schematic diagram of the groove structure in a specific implementation manner of the present invention.

[0026] Figure 3 It is a schematic diagram of the robot arrangement state in a specific implementation manner of the present invention.

[0027] Figure 4 It is a schematic diagram of a trackless all-position crawling welding robot system in a specific implementation manner of the present invention. DETAILED DESCRIPTION

[0028] The specific embodiments of the present invention will be described in detail below. In order to avoid too much unnecessary details, the well-known structures or functions will not be described in detail in the following examples. The approximate language used in the following examples can be used for quantitative expression, indicating that the quantity can be allowed to have a certain change without changing the basic function. Unless otherwise defined, the technical and scientific terms used in the following examples have the same meaning as those generally understood by those skilled in the art to which the present invention belongs.

[0029] Welding construction method of crawling welding robot for water pipes in pumped storage power stations:

[0030] 1. Process principle

[0031] The core of this process is to use a trackless welding robot equipped with a MAG welding method, using a mixed gas (80% Ar + 20% CO2) as the shielding gas to weld the pumped storage water pipeline. The process parameters and technical measures used have been rigorously verified by experiments.

[0032] 1.1 Selection of welding materials

[0033] The materials of pumped storage pipelines are mainly Q345R, 600MPa and 800MPa. The types of penstock welding materials should be compatible with the parent material and welding method, and the welding materials should have a factory quality certificate. The chemical composition, mechanical properties, diffusible hydrogen content and other technical parameters should meet the requirements of Article 2.0.7 of the "Specifications for the Manufacture, Installation and Acceptance of Penstocks for Hydropower and Water Conservancy Projects" (GB50766-2012). The welding wire selected for welding should match the type of steel being welded.

[0034] 1.2 Selection of welding method

[0035] Combined with the current quality level of pipeline assembly in the tunnel, the front side of the weld is primed with manual welding rods, and the crawling robot is equipped with MAG welding method to fill and cover the surface; the back side of the weld is cleaned with carbon arc air planing, and the manual welding rod is used to fill and cover the surface. When the crawling welding robot performs MAG welding, a mixed gas (80% Ar + 20% CO2) is selected as the shielding gas.

[0036] 1.3 Selection of process parameters

[0037] The welding parameters of the 5G position are shown in Table 1 below:

[0038] Table 1 Welding parameters of 5G position

[0039]

[0040] The welding parameters of the 6G position are shown in Table 2 below:

[0041] Table 2 Welding parameters of 6G position

[0042]

[0043] 1.4 Welding procedure qualification

[0044] 1) Prepare pre-welding process specifications

[0045] Combined with the mechanical properties requirements and weldability of the parent material, in order to ensure that the mechanical properties of the weld meet the requirements, a smaller heat input is required when welding with a crawling robot, and the welding parameters are set based on this.

[0046] Smaller heat input will increase the risk of base material segregation during welding. To solve this problem, technical measures such as preheating before welding and maintaining layer temperature during welding were added. To overcome the problem of unfused defects during welding at the 5G and 6G positions, technical measures such as increasing the tilt and adjusting the welding method were adopted.

[0047] 2) Process evaluation

[0048] According to the pre-welding procedure, welding of welding procedure qualification test pieces at positions 3G, 5G, and 6G was carried out. After the test pieces were welded, according to the national standards, the test pieces were subjected to weld appearance quality inspection, weld non-destructive testing (including MT, UT, TOFD), and physical and chemical testing (including tensile, bending, impact, and macroscopic metallography), and all were qualified.

[0049] 2. Construction process and key points

[0050] 2.1 Construction process

[0051] The construction process of the present invention mainly includes four main steps: groove prefabrication and workpiece assembly, pre-welding preparation, welding and welding inspection and repair. Figure 1 .

[0052] 2.2 Operation points

[0053] 2.2.1 Bevel prefabrication and bevel assembly

[0054] The pipe segment ring weld installed in the hole adopts the flux-cored wire gas shielded welding process, the groove processing angle of 20≤δ<32mm steel plate is 50~60°, the blunt edge is 0-1mm, the gap between the joints is 4-8mm, the misalignment is ≤2mm, and a "V"-shaped groove is opened. When the assembly accuracy meets the requirements, ceramic pads can be installed to achieve single-sided welding and double-sided forming, combined with the back seam air planing root cleaning process, otherwise the manual base robot filling and covering method is used for welding.

[0055] 32≤δ≤40mm Asymmetric double-sided V-shaped groove is used, groove gap is 1-2mm, blunt edge is 1-2mm. The groove angle of the positive seam is 50°, the depth is 2 / 3 of the test plate thickness, the groove angle of the back seam is 70°, the depth is 1 / 3 of the test plate thickness, ceramic liner is added, single-sided welding and double-sided forming are combined with the back seam air planing root cleaning process. The groove structure is as follows Figure 2 shown.

[0056] 2.2.2 Welding preparation

[0057] 2.2.2.1 Personnel preparation

[0058] All welders involved in steel pipe welding shall pass the examination according to DL / T 679, SL35 or "Test and Management Rules for Boiler Pressure Vessel Pressure Pipeline Welders" and have a welder certificate issued by the relevant competent authorities. Welders who have interrupted welding work for more than 6 months shall retake the examination. Generally speaking, as long as the personnel have some basic welding skills, the training time for welders is one week. After one week, they can basically operate the crawling welding robot and weld qualified welds.

[0059] The type of steel welded by the welder, the welding method and the welding position, etc. should all be consistent with the qualified items obtained by the welder himself in the examination.

[0060] 2.2.2.2 Equipment layout and fixing

[0061] According to the actual situation of the robot welding operation platform, the equipment of multiple robot systems are arranged, fixed and connected to the power supply, the layout is optimized to improve the welding efficiency and ensure the safety of the robot system during the platform lifting process. This welding is planned to use two robot systems for coordinated welding. The preliminary reference layout plan is as follows Figure 3 In order to ensure the safety of the equipment's electricity use and equipment safety, a power regulator is placed on the welding platform, and other auxiliary equipment of the crawling robot is fixed on the welding platform.

[0062] The entire weld is divided into sections according to the welding plan to ensure that the filling and cover welding of the weld can be completed in one day. In order to reduce welding stress, evenly distribute heat and ensure the stability of the weld structure, two sets of trackless full-position crawling welding robots are used for symmetrical welding.

[0063] 2.2.2.3 Wind protection measures before welding

[0064] According to the wind speed, choose appropriate wind protection methods and equipment, and formulate a wind protection plan to ensure that the welding quality is not affected by the ventilation in the cave.

[0065] 1) Under the premise of ensuring safe construction underground, if a wind curtain can be set up at the wellhead, it is preferred to set up a wind curtain. If a wind curtain cannot be set up, follow the following methods according to the wind speed.

[0066] 2) Detect wind speed. When the wind speed is greater than 2m / s and less than 4m / s, use the robot's first-level wind protection device (i.e. wind shield).

[0067] 2.2.2.4 Pre-welding treatment

[0068] Before welding, clean the scale, rust, slag, oil, water marks and other debris within the groove and within 20mm on both sides of the weld groove, and check the assembly size, groove size and positioning weld quality. Cracks, pores, slag inclusions and other defects on the positioning weld should be removed.

[0069] 2.2.2.5 Preheating and heating measures

[0070] Before welding, measure the humidity of the underground environment. When the relative humidity is greater than 80%, flame heating, electric heating or medium frequency heating should be used to heat both sides of the weld to remove moisture and prevent welding defects. After heating, use a wire brush to clean the oil and rust within 50mm on both sides of the groove and the edge of the groove, and polish to a metallic luster.

[0071] For welds that do not require preheating, when the ambient temperature is lower than 10°C or the humidity is greater than 80%, they should also be preheated appropriately to remove moisture to avoid welding porosity.

[0072] Weld seam heating shall comply with the following provisions: The width of the heating zone shall be 3 times the plate thickness on both sides of the welding center line and shall not be less than 100mm. The temperature shall be measured using an infrared thermometer, symmetrically at 50mm from the weld center line, with the distance between measuring points on each weld not exceeding 2m and not less than 3 points.

[0073] The interlayer temperature should be properly controlled during the welding process. The interlayer temperature should not be lower than the preheating temperature and should not exceed 200°C.

[0074] 2.2.3 Welding operation

[0075] 2.2.3.1 Confirmation of welding environment

[0076] Check and confirm that there is no obstruction within the robot's travel range (400mm above the weld), conduct a robot travel test, and confirm that there is no obstruction to the cable during travel and that the laser grasping is stable.

[0077] The entire weld is divided into sections according to the welding plan to ensure that the filling and cover welding of the sections can be completed in one day. Two sets of trackless full-position crawling welding robots are used for symmetrical welding to reduce welding stress.

[0078] 2.2.3.2 Welding process parameters

[0079] The 6G welding process parameters are shown in Table 3 below.

[0080] Table 3 6G welding process parameters

[0081]

[0082] The 5G welding process parameters are shown in Table 4 below.

[0083] Table 4 5G welding process parameters

[0084]

[0085] 2.2.3.3 Welding

[0086] Grind the tack weld area and grind both ends of the tack weld into a slope transition; if defects are found in the tack weld during the grinding process, remove the defects and add tack welds or re-tack welds if necessary.

[0087] Clean the back of the weld, paste the ceramic liner, and check that the center of the liner is consistent with the center of the weld. The liner needs to be re-pasted in the following situations: baking and dehumidification after pasting the liner; cleaning the groove on a large area after pasting the liner; not welding for more than 4 hours after pasting the liner. If the assembly gap cannot meet the robot welding requirements, use manual welding rods to prime and fill the cover with robots. Use carbon arc air planing to clean the root on the back, polish to a metallic luster, and then fill the cover with manual welding rods.

[0088] Check the appearance of the welding wire and make sure there is no water stain or rust before use.

[0089] Check the type of protective gas and adjust the protective gas flow rate to 20-30L / min. The gas inspection time must not be less than 30s.

[0090] Arc welding, the precautions during welding are shown in the following Table 5.

[0091] Table 5 Precautions for welding of 5G / 6G position welds

[0092]

[0093] After welding is completed, visual inspection and non-destructive testing are carried out.

[0094] 3. Materials and equipment

[0095] 3.1 Robotic welding system

[0096] Trackless full-position crawling welding robot system, composed of Figure 4 As shown in the figure, it mainly includes the robot body, robot control system, laser tracking system, welding power supply system and connecting cables. It adopts three-phase five-wire 380V power supply, and the grounding resistance is required to be less than 4 ohms.

[0097] The welding robot system is a commercially available finished product, for example, a trackless full-position crawling welding robot produced by Beijing Boqing Technology Co., Ltd. can be purchased. The welding robot system has a certificate of qualification, stable parameters, flexible adjustment, safety and reliability, and can meet the needs of welding parameters. The main technical data are shown in Table 6 below:

[0098] Table 6 Main parameters of welding robot

[0099]

[0100] 3.2 Welding materials

[0101] Welding wires should be placed in a ventilated, clean, dry warehouse with a room temperature not lower than 5°C and a relative humidity not higher than 70%. No other harmful media should be stored. A dedicated person should be responsible for storage and distribution, and keep records of the measured temperature, relative humidity and welding material distribution. Welding materials of different types, models, brands, batch numbers, specifications, and storage times should be stored in categories and clearly marked to avoid mixing. Welding materials should be distributed on a first-in, first-out basis. Rust and oil stains should be removed from welding wires before use. Welding material information is shown in Table 7 below.

[0102] Table 7 Welding material information

[0103]

[0104] The welding method adopted is FCAW (flux-cored gas welding), and the shielding gas is an argon-rich mixture (80% Ar+20% CO2). The welding weld has excellent formation, the molten iron is easy to control, and the problem of molten iron falling in the overhead welding position is overcome. There is less spatter, which is suitable for long-term and long-distance welding by robots.

[0105] 4. Quality Control

[0106] Engineering quality control standards include:

[0107] The welder certificate must comply with DL / T 679, SL35 or "Boiler Pressure Vessel Pressure Pipeline Welder Examination and Management Rules" and the heating must comply with the provisions of standard GB / T 18591.

[0108] GB 50766—2012 Specification for the Manufacturing, Installation and Acceptance of Penstocks for Hydropower and Water Conservancy Projects.

[0109] YB / T 4137-2005 "High Strength Steel with Low Welding Crack Sensitivity".

[0110] GB / T 1591-2008 “Low alloy high strength structural steel”.

[0111] GB 713-2014 "Steel Plates for Boilers and Pressure Vessels".

[0112] GB / T 32533-2016 “High-strength steel welding electrodes”.

[0113] GB / T 10045-2001 Carbon steel flux-cored welding wire.

[0114] GB / T 8110-2008 Carbon steel and low alloy steel welding wire for gas shielded arc welding.

[0115] GB / T 17493-2008 "Low alloy flux-cored welding wire".

[0116] GB / T 2650-2008 “Impact test method for welded joints”.

[0117] GB / T 2651-2008 “Tensile test method for welded joints”.

[0118] GB / T 2652-2008 “Tensile test methods for welds and deposited metals”.

[0119] GB / T 2653-2008 “Bending test method for welded joints”.

[0120] GB / T 2654-2008 “Test method for hardness of welded joints”.

[0121] DL / T 678-2013 General Technical Requirements for Welding of Power Steel Structures.

[0122] DL / T 868-2014 “Welding Procedure Qualification Procedure”.

[0123] SL 35-2011 "Examination Rules for Hydraulic Metal Structure Welders".

[0124] 5. Benefit Analysis

[0125] 5.1 Economic Benefits

[0126] Comparison of the efficiency of crawler robot welding and manual welding (taking the welding of 5G full-position large pipes with a diameter of 6.2 meters and a thickness of 32 mm as an example), the length of the entire weld is 19.5 meters, and the groove angle of the weld is 50°; the comparison results are shown in Table 8 below.

[0127] Table 8 Welding efficiency comparison information

[0128]

[0129] 1) Trackless all-position crawling welding robot, based on the improvement of cladding efficiency brought by the metallurgical electrode gas shielded welding process and the welding interruption caused by the robot's continuous welding, the welding speed can be increased by 50%.

[0130] 2) Comprehensive calculation from the perspective of direct welding costs: The cost of robot welding is only one-eighth of manual welding. Taking into account the cost sharing of robot equipment, the welding cost can be reduced to about 10,000 yuan, and the comprehensive welding cost can be reduced by about 60%; as shown in Table 8 above.

[0131] 3) The quality of robot welding is better than that of manual welding, and the surface forming such as weld height, width and flatness is more beautiful than that of manual welding.

[0132] 4) When the assembly quality meets the robot's welding requirements, the trackless full-position crawling welding robot can achieve single-sided welding and double-sided forming. The back side does not need to be cleaned by air planing or polished after air planing, which can further improve the welding efficiency.

[0133] 5) The continuous improvement of the trackless all-position crawling welding robot can gradually realize one person with two machines (with a molten pool camera installed), which will further reduce the welding cost.

[0134] 5.2 Environmental Benefits

[0135] Robot welding is much more hygienic than manual welding. There is no electrode head and the welding flux is much less than that of welding rods. If solid welding wire is used, there will be no welding flux. Robot welding also produces very little smoke, and the welder does not have to work so hard. If equipped with a molten pool camera, one welder can control at least two robots.

[0136] 5.3 Social Benefits

[0137] At present, the daily wage of each welder in underground welding is generally 800-1000 yuan a day, and the robot operator welder only earns 500 yuan a day at most. Two crawler machines only need two welders to weld a 6.2-meter diameter pipe, while two manual welders need at least 8 welders. In comparison, the economic difference is huge, and 6 people can be saved.

[0138] 6. Application Examples

[0139] The test welding was undertaken at the 6G position of the lower inclined shaft of the pumped storage pipeline of the 12th Bureau of State Grid (the length of the steel pipe of the upper inclined shaft of the water diversion is 359.22m, the angle is 50°, the diameter is 6.2m, the wall thickness is 22mm and 32mm, and the steel plate material is Q345R) and the 5G position of the horizontal tunnel (the steel pipe of the horizontal tunnel of the water diversion is 143.78m long, the diameter is 6.2m, the wall thickness is 32mm, and the steel plate material is 600MPa grade). The equipment used for welding is the 441 type trackless crawling robot produced by Beijing Boqing Technology Co., Ltd. The thickness of the base materials they welded is 22mm and 32mm respectively, and the first-time qualified rates of welding are 96% and 100% respectively.

[0140] The embodiments of the present invention are described in detail above, but the contents are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the scope of the present invention shall be included in the protection scope of the present invention.

Claims

1. A welding construction method for a pumped storage power station water pipe crawling welding robot, characterized in that: In this method, a manual electrode is used to prime the front side of the weld, and the robot is equipped with MAG welding to fill and cover the surface; a carbon arc air planer is used to clean the root of the weld on the back side, and the manual electrode is used to fill and cover the surface; when the robot performs MAG welding, a mixed gas containing 80% Ar and 20% CO2 is used as the protective gas.

2. The method for welding construction of a pumped storage power station water pipe crawling welding robot according to claim 1, characterized in that: For welding at the 5G position, when the base material is Q345R and the base material thickness is 24mm, the welding method of the first welding layer is SMAW, and its welding current is 150~160A, and the welding method of the second welding layer is FCAW, and its welding current is 210~220A, the welding voltage is 20~21V, and the welding speed is 140~150mm / min; the welding method of the first welding layer on the reverse side is SMAW, and its welding current is 165~180A.

3. The welding construction method of a crawling welding robot for a water pipe of a pumped storage power station according to claim 1, characterized in that: For welding at the 6G position, when the base material is Q345R and the base material thickness is 24mm, the welding method of the first welding layer is SMAW, and the welding current is 150~160A, the welding method of the second welding layer is FCAW, and the welding current is 190~210A, the welding voltage is 20~21V, and the welding speed is 140~150mm / min, the welding method of the third welding layer is FCAW, and the welding current is 220~230A, the welding voltage is 20~21V, and the welding speed is 300~330mm / min, and the welding method of the first welding layer on the reverse side is SMAW, and the welding current is 165~180A.

4. The welding construction method of a crawling welding robot for a water pipe of a pumped storage power station according to claim 1, characterized in that: The grooves are prefabricated and matched before welding. For the pipe segment ring welds installed in the hole, flux-cored gas shielded welding is used. The groove processing angle of 20≤δ<32mm steel plate is 50~60°, the blunt edge is 0-1mm, the gap between the joints is 4-8mm, the misalignment is ≤2mm, a V-shaped groove is opened, a ceramic liner is installed, single-sided welding and double-sided forming are combined with the back seam air planing root cleaning process, otherwise, manual primer robot filling and capping are used for welding; 32≤δ≤40mm all use asymmetric double-sided V-shaped grooves, the groove gap is 1-2mm, and the blunt edge is 1-2mm; the positive seam groove angle is 50°, the depth is 2 / 3 of the test plate thickness, the back seam groove angle is 70°, the depth is 1 / 3 of the test plate thickness, a ceramic liner is installed, single-sided welding and double-sided forming are combined with the back seam air planing root cleaning process.

5. The welding construction method of a crawling welding robot for a water pipe of a pumped storage power station according to claim 1, characterized in that: The robots are arranged and fixed before welding, wherein two robots are configured for each weld circle, a power regulator is placed on the welding platform, and the auxiliary equipment of the robots is fixed on the welding platform; the entire weld circle is divided into sections, and the two robots are arranged symmetrically.

6. The method for welding construction of a pumped storage power station water pipe crawling welding robot according to claim 1, characterized in that: Before welding, windproof measures are arranged, and the windproof measures include setting up a windproof curtain. When the windproof curtain cannot be set up, the wind speed is detected. When the wind speed is between 2 and 4 m / s, a windshield is set on the robot.

7. The welding construction method of a crawling welding robot for a water pipe of a pumped storage power station according to claim 1, characterized in that: Before welding, clean the scale, rust, slag, oil stains, and water marks within 20mm inside the groove and on both sides of the weld groove, and check the assembly dimensions, groove dimensions and positioning weld quality; remove cracks, pores, and slag inclusions on the positioning weld.

8. The method for welding construction of a pumped storage power station water pipe crawling welding robot according to claim 1, characterized in that: Before welding, measure the humidity of the underground environment. When the relative humidity is greater than 80%, use flame heating, electric heating or medium frequency heating to heat both sides of the weld to remove water vapor. After heating, use a wire brush to clean the oil and rust within 50mm inside the groove and on both sides of the groove edge, and polish to a metallic luster. In the process of heating the weld, the width of the heating zone is 3 times the plate thickness on both sides of the welding center line, and not less than 100mm. The temperature is measured using an infrared thermometer, symmetrically at 50mm from the center line of the weld, and the distance between the measuring points of each weld is not more than 2m, and there are no less than 3 points. During the welding process, the interlayer temperature is controlled not to be lower than the preheating temperature, and not to exceed 200℃.

9. The method for welding construction of a pumped storage power station water pipe crawling welding robot according to claim 1, characterized in that: Perform the following steps before welding: 1) Grind the tack weld parts and grind the two ends of the tack weld into a slope transition; if defects are found in the tack weld during the grinding process, remove the defects or add tack welds or re-tack welds; 2) Clean the back of the weld, paste the ceramic liner, and check that the center of the liner is consistent with the center of the weld; re-paste the liner when the following conditions occur: baking and dehumidification are performed after the liner is pasted; cleaning the groove exceeds a certain area after the liner is pasted; no welding is performed for more than 4 hours after the liner is pasted; When the assembly gap cannot meet the robot welding requirements, use manual welding rods to prime and the robot to fill the cover surface; use carbon arc air planer to clean the root on the back, polish to a metallic luster, and then fill the cover surface with manual welding rods; 3) Check the appearance of the welding wire to ensure there are no water stains or rust; 4) Check the type of protective gas, adjust the protective gas flow rate to 20-30L / min, and the gas inspection time should not be less than 30s; 5) Arc welding.

10. The welding construction method of a crawling welding robot for a water pipe of a pumped storage power station according to claim 9, characterized in that: During the arc welding process: the arc starting points and arc ending points of the circumferential weld are staggered at a spacing of not less than 30 mm; during multi-layer and multi-pass welding, the welding gun angle of the first welding pass of each layer of weld is tilted downward by 10°, and the welding gun angle of the last welding pass is tilted upward by 10°, and the welding guns of other layers are vertical; when the base weld passes through the tack weld, the welding speed is increased in advance, the arc is stopped, and the arc is restarted at the end of the tack weld; for the downslope, for each layer of weld, the swing amplitude of the first weld is controlled to be ≤2 mm; for the upslope, for each layer of weld, when welding the last weld, the upper dwell time is increased from 0.2s to 0.4s.

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