Pumped storage power station water storage pipeline crawling welding robot welding construction method

Abstract

The application provides a pumped storage power station water storage pipeline crawling welding robot welding construction method, and belongs to the technical field of pipeline welding. In the method, a manual welding rod is used for bottoming on the front of a weld, and MAG welding carried by the robot is used for filling and facing; a carbon arc gas gouging is used for cleaning the back of the weld, and a manual welding rod is used for filling and facing; when the robot performs MAG welding, mixed gas containing 80% Ar and 20% CO2 is used as protective gas. In the pipeline welding process, the crawling robot is used to replace manual welding, the labor intensity of welders is reduced, the welding automation degree is improved, and the welding quality is improved. The application is suitable for the crawling welding robot welding operation of large-diameter pipeline tunnels in various pumped storage power stations and other hydropower industries, including the 5G and 6G positions of the upper and lower inclined shafts and the flat hole of the water conveying pipeline of the pumped storage power station, and has outstanding technical advantages and significant economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of pipeline welding technology, specifically a welding construction method for a crawling welding robot for pumped storage power station water storage pipelines. Background Technology

[0002] Welding of pressure steel pipes for the water conveyance system is a crucial step in the installation and construction of a power station. Taking a pumped storage power station under construction as an example, the water conveyance system encompasses the upper reservoir inlet / outlet, upper intake tunnel, upper intake inclined shaft, middle intake tunnel, lower intake inclined shaft, lower intake tunnel, intake steel branch pipe, intake steel branch pipe, tailrace branch pipe, tailrace tunnel, tailrace surge chamber, and lower reservoir inlet / outlet. The total length of the water conveyance system between the upper and lower reservoir inlets / outlets is approximately 2100.3m, of which the intake system is approximately 1171.4m long and the tailrace system is approximately 928.9m long. The materials used for the various pipes include Q345R, 600MPa, and 800MPa high-strength steel.

[0003] Currently, automated welding of pressure steel pipes has been achieved in steel pipe processing plants. However, when installing them inside tunnels, manual welding (MAG or manual welding) is still the primary method. Due to the narrow construction sites and difficulties in tunnels, vertical and overhead welding of butt joints requires a high level of technical skill, making it difficult to guarantee quality. Furthermore, the welding process generates a large amount of fumes and dust, polluting the site and causing significant harm to workers. To address this issue, welding robots specifically designed for particular working conditions have been increasingly widely used in recent years. Although relatively mature welding robots are available for sale, determining the optimal welding process for practical applications such as pumped storage power station pipelines remains a technical challenge that needs further investigation. Summary of the Invention

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

[0005] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0006] A welding construction method for a crawling welding robot for pumped storage power station water storage pipelines is described. In this method, the front side of the weld is treated with manual welding rods for the root pass, and then filled and covered by MAG welding by the robot. The back side of the weld is cleaned with carbon arc gouging, and then filled and covered by manual welding rods. When the robot performs MAG welding, a mixture of 80% Ar and 20% CO2 is used as the shielding gas.

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

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

[0009] As a preferred method, beveling and beveling are prefabricated and assembled before welding. For the circumferential welds of the pipe sections installed inside the tunnel, flux-cored wire gas shielded welding is used. For steel plates with a diameter of 20 ≤ δ < 32 mm, the beveling angle is 50~60°, the blunt edge is 0-1 mm, the gap is 4-8 mm, and the misalignment is ≤ 2 mm. A V-shaped beveling is made, a ceramic backing is installed, and single-sided welding is performed with double-sided forming. This is combined with the back seam air gouging process. Otherwise, manual rooting and robot filling and covering are used for welding. For steel plates with a diameter of 32 ≤ δ ≤ 40 mm, an asymmetrical double-sided V-shaped beveling is used, with a beveling gap of 1-2 mm and a blunt edge of 1-2 mm. The beveling angle of the front seam is 50°, and the depth is 2 / 3 of the test plate thickness. The beveling angle of the back seam is 70°, and the depth is 1 / 3 of the test plate thickness. A ceramic backing is installed, and single-sided welding is performed with double-sided forming. This is combined with the back seam air gouging process.

[0010] Preferably, the robots are arranged and fixed before welding, wherein two robots are configured for each weld bead, 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 bead is divided into segments, and the two robots are arranged symmetrically.

[0011] Preferably, wind protection measures are arranged before welding. These measures include setting up windproof curtains. If windproof curtains cannot be set up, the wind speed is detected. If the wind speed is between 2 and 4 m / s, a windproof cover is set up on the robot.

[0012] As a preferred method, before welding, clean the inside of the groove and within 20mm on both sides of the weld groove to remove oxide scale, rust, slag, oil, and water stains, and check the assembly dimensions, groove dimensions, and the quality of the tack welds; remove cracks, pores, and slag inclusions from the tack welds.

[0013] As a preferred method, 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 is used to heat both sides of the weld to remove moisture. After heating, the oil and rust inside the bevel and within 50mm on both sides of the bevel edge are cleaned with a wire brush and polished to a metallic luster. During the heating process of 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 measured at 50mm from the weld center line, with the measurement points on each weld not more than 2m apart and not less than 3 points. During the welding process, the interpass temperature is controlled to be not lower than the preheating temperature and not more than 200℃.

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

[0015] 1) 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, clean the defects, add tack welds, or re-tack weld.

[0016] 2) Clean the back of the weld, attach the ceramic backing, and check that the center of the backing is aligned with the center of the weld. Reattach the backing if any of the following occurs: the backing is baked and dehumidified after being attached; the bevel is cleaned beyond a certain area after the backing is attached; or welding is not performed more than 4 hours after the backing is attached.

[0017] When the assembly gap cannot meet the requirements of robot welding, use manual welding rods for the root pass and then use the robot to fill and cover the surface; clean the back side with carbon arc gouging, grind it to a metallic luster, and then fill and cover the surface with manual welding rods.

[0018] 3) Inspect the appearance of the welding wire to ensure it is free of water stains and rust;

[0019] 4) Check the protective gas type and adjust the protective gas flow rate to 20-30 L / min. The gas check time should be no less than 30 seconds.

[0020] 5) Arc welding.

[0021] Preferably, during the arc-starting welding process: the arc-starting and arc-ending points of the circumferential weld are staggered by a distance of not less than 30mm; during multi-layer, multi-pass welding, the welding torch angle for the first pass of each layer is tilted downwards by 10°, the welding torch angle for the last pass is tilted upwards by 10°, and the welding torches for other passes are vertical; when the root pass passes the locating weld, the welding speed is increased in advance and the arc is stopped, and the arc is restarted at the end of the locating weld; for the down bevel, the swing amplitude of the first pass of each layer is controlled to be ≤2mm; for the up bevel, the dwell time for the last pass of each layer is increased from 0.2s to 0.4s.

[0022] The core of this invention is the use of a trackless welding robot equipped with a MAG welding method, employing a mixed gas (80% Ar + 20% CO2) as the shielding gas for welding pumped-storage water pipelines. All process parameters and technical measures adopted have undergone rigorous experimental verification. This invention replaces manual welding with a crawling robot in the pipeline welding process, reducing the labor intensity of welders, increasing the degree of automation in welding, and thus comprehensively improving welding quality, bringing significant benefits to the construction of pumped-storage power stations.

[0023] This invention is applicable to robotic welding operations within large-diameter pipeline tunnels of various pumped-storage power stations and other hydropower industries, including 5G and 6G positions in the upper and lower inclined shafts and horizontal tunnels of pumped-storage power station water transmission pipelines. It can also be extended to welding operations in similar scenarios in pressure vessels, shipbuilding, and rail transportation. Attached Figure Description

[0024] Figure 1 This is a flowchart of the construction process of the present invention.

[0025] Figure 2 This is a schematic diagram of the bevel structure in a specific embodiment of the present invention.

[0026] Figure 3 This is a schematic diagram of the robot deployment state in a specific embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram of a trackless, all-position crawling welding robot system according to a specific embodiment of the present invention. Detailed Implementation

[0028] The specific embodiments of the present invention will be described in detail below. To avoid excessive and unnecessary detail, well-known structures or functions will not be described in detail in the following embodiments. The approximate language used in the following embodiments is for quantitative purposes, indicating that a certain degree of variation in quantity is permissible without changing the basic function. Unless otherwise defined, the technical and scientific terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art to which this invention pertains.

[0029] Welding construction method of crawling welding robot for pumped storage power station water storage pipelines:

[0030] 1. Process Principle

[0031] The core of this process is the use of a trackless welding robot equipped with a MAG welding method, employing a mixed gas (80% Ar + 20% CO2) as the shielding gas for welding pumped-storage water pipelines. All process parameters and technical measures used have undergone rigorous experimental verification.

[0032] 1.1 Selection of Welding Materials

[0033] The main materials used in pumped storage pipelines are Q345R, 600MPa, and 800MPa steel. The type of welding material used for pressure steel pipes should be compatible with the base material and welding method. Furthermore, the welding material should have a factory quality certificate, and its chemical composition, mechanical properties, diffusible hydrogen content, and other technical parameters should meet the requirements of Article 2.0.7 of the "Code for Fabrication, Installation and Acceptance of Pressure Steel Pipes for Hydropower and Water Conservancy Projects" (GB50766-2012). The welding wire selected for welding should be compatible with the steel grade being welded.

[0034] 1.2 Selection of Welding Method

[0035] Based on the current quality level of pipeline assembly within the tunnel, the weld face is treated with manual welding rods for the root pass, followed by MAG welding using a crawling robot for the filler and cover passes. The weld face is treated with carbon arc gouging for the root pass, followed by manual welding rods for the filler and cover passes. When using the crawling welding robot for 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 for the 5G position are shown in Table 1 below:

[0038] Table 1 Welding parameters for position 5G

[0039]

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

[0041] Table 2 Welding parameters for position 6G

[0042]

[0043] 1.4 Welding Procedure Qualification

[0044] 1) Compile pre-welding process specifications

[0045] In order to ensure that the mechanical properties of the weld meet the requirements, a smaller heat input is required when using a crawler robot for welding, taking into account the mechanical properties of the base material and weldability. All welding parameters are set based on this.

[0046] Smaller heat input increases the risk of base material segregation during welding. To address this issue, preheating before welding and maintaining the layer temperature during welding have been implemented. To overcome the problem of incomplete fusion defects during welding at 5G and 6G positions, measures such as increasing the tilting angle and adjusting the routing method have been adopted.

[0047] 2) Process evaluation

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

[0049] 2. Construction process and key points

[0050] 2.1 Construction Process Flow

[0051] The construction process of this invention mainly includes four stages: bevel prefabrication and workpiece assembly, pre-welding preparation, welding, and welding inspection and repair. See details... Figure 1 .

[0052] 2.2 Key Operational Points

[0053] 2.2.1 Bevel prefabrication and bevel assembly

[0054] The circumferential welds of the pipe sections installed inside the tunnel are produced using flux-cored wire gas shielded welding. For steel plates with a diameter of 20 ≤ δ < 32 mm, the beveling angle is 50~60°, the blunt edge is 0-1 mm, the butt joint gap is 4-8 mm, and the misalignment is ≤ 2 mm. A "V" shaped beveling is used. When the assembly accuracy meets the requirements, a ceramic backing can be added to achieve single-sided welding and double-sided forming. This is combined with the back seam air gouging process. Otherwise, the welding is carried out by manual bottom plating and robot filling and covering.

[0055] For diameters 32 ≤ δ ≤ 40 mm, asymmetrical double-sided V-shaped bevels are used, with a bevel gap of 1-2 mm and a blunt edge of 1-2 mm. The bevel angle for the front seam is 50°, and the depth is 2 / 3 of the test plate thickness. The bevel angle for the back seam is 70°, and the depth is 1 / 3 of the test plate thickness. A ceramic backing is added, and single-sided welding with double-sided forming is used, combined with air gouging for back seam cleaning. The bevel structure is as follows... Figure 2 As shown.

[0056] 2.2.2 Welding Preparation

[0057] 2.2.2.1 Personnel Preparation

[0058] All welders involved in steel pipe welding must pass the examination according to DL / T 679, SL35, or the "Rules for Examination and Management of Welders for Boilers, Pressure Vessels, and Pressure Pipelines" and possess a welder's qualification certificate issued by the relevant competent authority. Welders who have interrupted their welding work for more than 6 months must retake the examination. Generally, for anyone with basic welding knowledge, the training period for welders is one week. After one week, most people can operate the crawler welding robot and weld qualified welds.

[0059] The type of steel, welding method, and welding position that a welder welds must all be consistent with the qualified items obtained by the welder in the examination.

[0060] 2.2.2.2 Equipment Layout and Fixing

[0061] Based on the actual conditions of the robotic welding platform, the layout, fixing, and power connection of multiple robot systems will be carried out. The optimized layout will improve welding efficiency and ensure the safety of the robot systems during platform lifting and lowering. This welding operation will utilize two robot systems for coordinated welding. A preliminary layout plan is as follows: Figure 3 As shown. To ensure the safety of the equipment's power supply and the equipment itself, a voltage regulator is placed on the welding platform, and other auxiliary equipment for the crawling robot is fixed on the welding platform.

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

[0063] 2.2.2.3 Pre-welding wind protection measures

[0064] Based on the wind speed, select appropriate wind protection methods and equipment, and formulate a wind protection plan to ensure that the welding quality is not affected by the ventilation inside the tunnel.

[0065] 1) Provided that safe underground construction is ensured, if a windproof curtain can be installed at the wellhead, it should be installed first. If a windproof curtain cannot be installed, the following methods should be followed according to the wind speed.

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

[0067] 2.2.2.4 Pre-welding treatment

[0068] Before welding, clean the bevel and the area within 20mm on both sides of the weld bevel to remove scale, rust, slag, oil, water stains, and other debris. Also check the assembly dimensions, bevel dimensions, and the quality of the tack welds. Cracks, porosity, slag inclusions, and other defects on the tack welds should be removed.

[0069] 2.2.2.5 Preheating and Heating Measures

[0070] Before welding, the humidity of the underground environment should be measured. If 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 inside the bevel and within 50mm on both sides of the bevel edge, and polish until a metallic luster is achieved.

[0071] For welds that do not require preheating, if the ambient temperature is below 10℃ or the humidity is above 80%, preheating should be performed appropriately to remove moisture and prevent weld porosity.

[0072] The heating of welds shall comply with the following provisions: the width of the heating zone shall be three times the plate thickness on both sides of the weld centerline, and not less than 100 mm. Temperature measurement shall be performed using an infrared thermometer, symmetrically measured at 50 mm from the weld centerline, with a spacing of no more than 2 m between measurement points on each weld, and no fewer than three points.

[0073] During the welding process, the interpass temperature should be properly controlled. The interpass temperature should not be lower than the preheating temperature and should not exceed 200℃.

[0074] 2.2.3 Welding Operation

[0075] 2.2.3.1 Confirmation of Welding Environment

[0076] After checking and confirming that there are no obstructions within the robot's travel range (400mm above the weld), a robot travel test was conducted to confirm that the cable was unobstructed during travel and that the laser gripping was stable.

[0077] According to the welding plan, the entire weld seam is divided into segments to ensure that the filling and cover welding of each segment can be completed in one day. Two sets of trackless all-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, clean the defects, and add or re-tack weld if necessary.

[0087] Clean the back of the weld, apply a ceramic backing, and check that the center of the backing aligns with the center of the weld. The backing needs to be reapplied if: the backing was baked and dehumidified after application; the bevel was extensively cleaned after application; or more than 4 hours have passed since the backing was applied without welding. If the assembly clearance does not meet the requirements for robotic welding, use manual welding rods for the root pass, followed by robotic filler and cover pass. Clean the back of the weld with carbon arc gouging, grind to a metallic sheen, and then use manual welding rods for the cover pass.

[0088] Inspect the appearance of the welding wire to ensure it is free of water stains and rust before use.

[0089] Check the protective gas type and adjust the protective gas flow rate to 20-30 L / min. The gas check time should not be less than 30 seconds.

[0090] For arc welding, the precautions during the welding process are shown in Table 5 below.

[0091] Table 5 Welding Precautions for 5G / 6G Positions

[0092]

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

[0094] 3. Materials and Equipment

[0095] 3.1 Robotic Welding System

[0096] The trackless all-position crawling welding robot system consists of the following components: Figure 4 As shown, it mainly consists of the robot body, robot control system, laser tracking system, welding power supply system, and connecting cables. It uses a three-phase five-wire 380V power supply, and the grounding resistance is required to be less than 4 ohms.

[0097] This welding robot system is a commercially available finished product; for example, the trackless all-position crawling welding robot produced by Beijing Boqing Technology Co., Ltd. can be purchased. The welding robot system has a certificate of conformity, stable parameters, flexible adjustment, and high safety and reliability, and can meet the requirements 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 wire should be stored in a specially designated warehouse that is well-ventilated, clean, dry, and at a temperature not lower than 5°C and a relative humidity not higher than 70%. No other harmful media should be stored there. The warehouse should be managed and distributed by designated personnel, and records of measured temperature, relative humidity, and welding material distribution should be maintained. Welding materials of different varieties, models, brands, batch numbers, specifications, and storage times should be stored separately with clear distinguishing marks to prevent mixing. Welding materials should be distributed according to a first-in, first-out (FIFO) principle. Welding wire should be cleaned of rust and oil before use. Welding material information is shown in Table 7 below.

[0102] Table 7 Welding Material Information

[0103]

[0104] The welding method used is FCAW (flux-cored wire gas shielded welding), and the shielding gas is an argon-rich mixture (80%Ar+20%CO2). The weld formation is excellent, the molten metal is easy to control, it overcomes the problem of molten metal falling in overhead welding position, and there is less spatter, making it suitable for long-term and long-distance robotic welding.

[0105] 4. Quality Control

[0106] Engineering quality control standards include:

[0107] Welder certificates must comply with DL / T 679, SL35 or the "Rules for Examination and Management of Welders for Boilers, Pressure Vessels and Pressure Pipelines". Heating must comply with the provisions of standard GB / T 18591.

[0108] GB 50766—2012 Specification for Fabrication, Installation and Acceptance of Pressure Steel Pipes for Hydropower and Water Conservancy Projects.

[0109] YB / T 4137-2005 High-strength steel with low weld 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 welding flux-cored wire.

[0116] GB / T 2650-2008 Impact Test Method for Welded Joints.

[0117] GB / T 2651-2008 Tensile testing method for welded joints.

[0118] GB / T 2652-2008 Tensile testing method for welds and deposited metals.

[0119] GB / T 2653-2008 Test method for bending of welded joints.

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

[0121] DL / T 678-2013 General Technical Conditions for Welding of Steel Structures in Power Systems

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

[0123] SL 35-2011 Examination Rules for Welders of Hydraulic Metal Structures.

[0124] 5. Benefit Analysis

[0125] 5.1 Economic Benefits

[0126] A comparison of the efficiency of crawling robot welding and manual welding (taking a 5G all-position large pipe 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 bevel 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 improved cladding efficiency brought by the gas metal arc welding process and the welding interruption caused by continuous robot welding, the welding speed can be increased by 50%.

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

[0131] 3) Robot welding produces better quality than manual welding, and the surface finish, such as weld height, width, and flatness, is more aesthetically pleasing than that of manual welding.

[0132] 4) Provided that the assembly quality meets the welding requirements of the robot, the trackless all-position crawling welding robot can achieve single-sided welding and double-sided forming, eliminating the need for air gouging to clean the root and grinding after air gouging on the reverse side, which can further improve welding efficiency.

[0133] 5) Continuous improvements to trackless all-position crawling welding robots will gradually enable one person to operate two machines (with a molten pool camera installed), further reducing welding costs.

[0134] 5.2 Environmental benefits

[0135] Robotic welding is much more hygienic than manual welding. There are no welding rod ends, and the welding flux is much less than that of welding rods. If solid welding wire is used, there is no welding flux. In addition, robotic welding produces very little smoke and dust, and the welder does not have to work as hard. If equipped with a molten pool camera, one welder can control at least two robots.

[0136] 5.3 Social Benefits

[0137] Currently, the daily wage for each welder in underground welding is generally 800-1000 yuan, while the daily wage for a robot-operated welder is at most 500 yuan. For a weld of a 6.2-meter diameter pipe, two crawler machines only require two welders, while two manual welders require at least eight welders. In comparison, the economic difference is huge, and six people can be saved.

[0138] 6. Application Examples

[0139] The test welding was conducted at position 6G of the lower inclined shaft of the pumped storage pipeline of the State Grid Twelfth Bureau (the steel pipes of the upper inclined shaft are both 359.22m long, 50° angle, 6.2m in diameter, and 22mm and 32mm in wall thickness, made of Q345R steel plate) and position 5G of the horizontal tunnel (the steel pipes of the horizontal tunnel are 143.78m long, 6.2m in diameter, 32mm in wall thickness, made of 600MPa grade steel plate). The welding equipment used was a 441-type trackless crawling robot manufactured by Beijing Boqing Technology Co., Ltd. The base material thicknesses welded were 22mm and 32mm respectively, and the first-pass yield rates were 96% and 100% respectively.

[0140] The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the scope of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of welding construction of a pumped storage power plant water storage pipeline crawling welding robot, characterized in that, In the method, the front of the weld is prepared by manual electrode, and the filling and surface are prepared by MAG welding of the robot; the back of the weld is prepared by carbon arc gouging, and the filling and surface are prepared by manual electrode; when the robot is MAG welding, mixed gas containing 80% Ar and 20% CO2 is used as protective gas; Before welding, the robot is arranged and fixed, two robots are arranged for each weld, a power stabilizer is placed on the welding platform, and the auxiliary equipment of the robot is fixed on the welding platform; the whole weld is segmented, and the two robots are arranged symmetrically; Before welding, windproof measures are arranged, which include setting a windproof curtain, when the windproof curtain cannot be set, the wind speed is detected, and when the wind speed is between 2-4 m / s, a windproof cover is set on the robot; Before welding, the following steps are sequentially performed: 1) grinding the positioning welding position, and grinding the two ends of the positioning welding into a slope transition; when defects are found in the grinding process, the defects are cleaned or additional positioning welding or repositioning welding is performed; 2) cleaning the back of the weld, sticking ceramic pads, and checking that the center of the pad is consistent with the center of the weld; when the following conditions occur, the pad is re-stuck: the pad is re-stuck after baking and drying; the pad is re-sticked after cleaning the groove for more than a certain area; the pad is re-sticked after more than 4 hours without welding; 3) check the appearance of the welding wire to ensure that there is no water stain or rust; 4) check the type of protective gas, adjust the protective gas flow to 20-30 L / min, and the gas detection time is not less than 30 s; 5) arc welding; During the arc welding, the arc starting point and the arc ending point of the girth weld are staggered by a distance of not less than 30 mm; when multi-layer and multi-pass welding is performed, the first pass of each layer of weld is inclined downward by 10°, the last pass is inclined upward by 10°, and the welding gun of other layers is vertical; when the backing welding passes through the positioning weld, the welding speed is increased and the arc is stopped, and the end of the positioning weld is re-arc welded; for the lower groove, the first pass of each layer of weld is controlled to have a swing of ≤2 mm; for the upper groove, the upper dwell time of the last pass of each layer of weld is increased from 0.2 s to 0.4 s.

2. The pumped storage power plant reservoir pipe creeping welding robot welding construction method according to claim 1, characterized by, For welding at the 5G position, when the base material is Q345R and the thickness of the base material is 24 mm, the welding method of the first welding level is SMAW, the welding current is 150-160 A, the welding method of the second welding level is FCAW, 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 level on the back is SMAW, and the welding current is 165-180 A.

3. The pumped storage power plant reservoir pipe creeping welding robot welding construction method according to claim 1, characterized by, For the 6G position welding, when the base material is Q345R and the base material thickness is 24 mm, the welding method of the first welding level is SMAW, the welding current is 150-160 A, the welding method of the second welding level is FCAW, 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, 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, the welding current is 165-180 A.

4. The pumped storage power plant reservoir pipe creeping welding robot welding construction method according to claim 1, characterized by, Before welding, the oxide scale, rust, slag, oil stains, water marks in the groove and on both sides of the weld within 20 mm are cleaned, and the assembly size, groove size and quality of the positioning weld are checked; cracks, pores and slag on the positioning weld are removed.

5. The pumped storage power plant reservoir pipe creeping welding robot welding construction method according to claim 1, characterized by, Before welding, the humidity of the underground environment is measured, and when the relative humidity is greater than 80%, flame heating, electric heating or medium frequency heating is used to heat the two sides of the weld to remove water vapor; after heating, the oil and rust within 50 mm of the groove and the edge of the groove are cleaned with a steel wire brush, and polished to a metallic luster; during the heating of the weld, the width of the heating area is 3 times the plate thickness on both sides of the welding center line, and is not less than 100 mm; the temperature measurement uses an infrared thermometer, and is measured symmetrically at a distance of 50 mm from the welding center line, the spacing between each measurement point of the weld is not greater than 2 m, and there are not less than 3 points; during the welding process, the interlayer temperature is controlled to be not less than the preheating temperature, and not more than 200 DEG C.

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