Narrow gap welding process for water inlet ball valve of pumped storage power station

Abstract

The invention discloses a narrow gap welding process for a water inlet ball valve of a pumped storage power station, which comprises the following steps of: S1, roughly machining an upper valve body and a lower valve body of the water inlet ball valve, machining other parts of a valve except a machining size reserved on a sealing surface, preliminarily machining the boundary dimension of the valve body to be close to a design requirement according to a preset process requirement, and machining the boundary dimension of the valve body to be close to the design requirement; meanwhile, it is guaranteed that indexes such as the surface roughness meet the basic conditions of follow-up welding and overall assembly, and it is guaranteed that the dimensional tolerance of all parts of the valve body is controlled within 0.3 mm; and S2, the exterior of the valve, the interior of the upper valve body and the interior of the lower valve body are sprayed with high-temperature-resistant paint, and the high-temperature-resistant paint has good high temperature resistance, corrosion resistance and heat insulation performance. The welding process solves the problems that in the prior art, when the water inlet ball valve is welded, the welding quality is difficult to guarantee, the deformation amount is large, the welding material loss is large, and the welding time is long, the overall welding effect and using performance of the water inlet ball valve are improved, and the production cycle of the water inlet ball valve is effectively shortened.

Description

Technical Field

[0001] The invention relates to the technical field of welding technology, and in particular to a narrow gap welding technology for a water inlet ball valve of a pumped storage power station. Background Art

[0002] Water inlet ball valves are widely used in many fields such as water conservancy projects. The valve body structure is relatively complex and large in size, and the welding quality and precision requirements are extremely high. Traditional welding methods often make it difficult to effectively control the deformation of the valve body and ensure key indicators such as sealing performance while ensuring welding strength. As an advanced welding technology, narrow gap welding has certain advantages in dealing with such large and complex structure welding, but there is currently a lack of narrow gap welding processes specifically optimized for water inlet ball valves to fully meet the high-quality use requirements of water inlet ball valves after welding.

[0003] Therefore, it is necessary to design a narrow gap welding process for the water inlet ball valve of a pumped storage power station to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings existing in the prior art, and to propose a narrow gap welding process for the water inlet ball valve of a pumped storage power station. The welding process solves the problems existing in the prior art when welding the water inlet ball valve, such as difficulty in ensuring the welding quality, large deformation, large welding material loss, and long welding time. It improves the overall welding effect and performance of the water inlet ball valve and effectively shortens the production cycle of the water inlet ball valve.

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

[0006] A narrow gap welding process for a water inlet ball valve of a pumped storage power station comprises the following steps:

[0007] S1: Rough machining is performed on the upper valve body and the lower valve body of the water inlet ball valve, and the rest of the valve is machined except for the sealing surface. According to the predetermined process requirements, the outer dimensions of the valve body are preliminarily machined to be close to the design requirements, and at the same time, its surface roughness and other indicators are ensured to meet the basic conditions for subsequent welding and overall assembly, and the dimensional tolerance of each part of the valve body is controlled within 0.3mm;

[0008] S2: spraying the outside of the valve (2), the upper valve body (1) and the inside of the lower valve body (3) with a high temperature resistant coating, which has good high temperature resistance, corrosion resistance and heat insulation performance;

[0009] S3: Install the valve into the upper valve body and the lower valve body, fix the shaft surfaces at both ends with tooling, and adjust the sealing surface to the center;

[0010] S4: Fix the upper valve body and the lower valve body with a mechanical clamp and place the weld in a horizontal position;

[0011] S5: Automatic welding with a narrow gap welding gun is used for the welding groove of the spherical part of the valve body;

[0012] S6: The same part of the valve body flange (4) and the valve body spherical surface groove is welded automatically by narrow gap welding, and the remaining part is cut into a larger groove by gas cutting device and manually welded;

[0013] S7: During the entire welding process, the surface to be welded is locally heated and maintained within a certain temperature range, and welding is performed using an automatic narrow gap welding gun;

[0014] S8: To reduce deformation, the valve bodies on both sides are welded at the diagonal positions at the same time;

[0015] S9: Turn the valve to a suitable position and clean the internal weld;

[0016] S10: Put the water inlet ball valve as a whole into the annealing furnace for annealing treatment before entering the next process.

[0017] Preferably, when the valve is installed in the upper valve body and the lower valve body, after the axial surfaces at both ends are fixed by tooling, the error of adjusting the sealing surface to the center position is controlled within a preset allowable error range.

[0018] Preferably, in the automatic welding of the valve body spherical surface welding and the narrow gap welding of the valve body flange, the welding parameters are set according to the material and thickness of the valve body.

[0019] Preferably, when the sealing surface is locally heated, the temperature is monitored in real time by a temperature sensor, and the heating temperature needs to be within a set temperature range.

[0020] Preferably, during the simultaneous welding of the diagonal positions of the valve bodies on both sides, the deformation of the valve bodies needs to be detected in real time, and when it exceeds the allowable range, the welding parameters are adjusted in time or corrective measures are taken.

[0021] Preferably, the water inlet ball valve is placed as a whole in an annealing furnace for annealing according to a predetermined annealing process curve, and the parameters of the annealing process curve are determined according to the material of the valve body.

[0022] Preferably, the function of the tooling is to firmly fix the axial surfaces at both ends of the valve through its precise positioning and reliable clamping device, thereby ensuring that the position of the valve in the valve body is relatively stable. A dial indicator is provided in the tooling, and the sealing surface is carefully adjusted to the center position through the dial indicator, so that the error of the sealing surface adjustment is strictly controlled.

[0023] Preferably, a level is provided in the mechanical fixture, and the position of the weld is calibrated using the level tool to place the weld accurately in a horizontal position.

[0024] Preferably, during the heating process of the sealing surface, a temperature sensor is provided to monitor the temperature in real time to ensure that the heating temperature is strictly within a set temperature range.

[0025] The present invention has the following beneficial effects:

[0026] 1. Compared with the existing technology, the narrow gap welding specially designed for each part of the water inlet ball valve and the matching process steps such as manual welding, preheating, symmetrical welding, etc. effectively ensure the welding strength, making the welding part of the water inlet ball valve firm and reliable and able to withstand long-term working pressure;

[0027] 2. Compared with the existing technology, the reasonable assembly and fixing method and deformation control measures such as diagonal simultaneous welding are adopted, which greatly reduces the deformation of the valve body during the welding process, ensures the overall shape accuracy of the water inlet ball valve, and is conducive to subsequent installation and use;

[0028] 3. Compared with the existing technology, the special welding treatment of the sealing surface and subsequent processes such as annealing have improved the sealing performance, reduced the risk of leakage, extended the service life of the water inlet ball valve, and improved its stability and reliability in engineering applications such as water conservancy. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A flow chart of a narrow gap welding process for a water inlet ball valve of a pumped storage power station proposed by the present invention;

[0030] Figure 2 It is a structural schematic diagram of the water inlet ball valve;

[0031] Figure 3 It is a structural schematic diagram of the spherical welding groove of the valve body;

[0032] Figure 4 It is a schematic diagram of the welding groove between the valve body flange surface and the spherical valve;

[0033] Figure 5 Schematic diagram of the weld structure.

[0034] In the figure: 1 upper valve body, 2 valve, 3 lower valve body, 4 flange. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0036] Reference Figure 1 - Figure 5 , a narrow gap welding process for a water inlet ball valve of a pumped storage power station, comprising the following steps:

[0037] S1: Rough machining is performed on the upper valve body 1 and the lower valve body 3 of the water inlet ball valve, and the rest of the valve 2 except for the machining size of the sealing surface is machined (reserving a fine machining allowance of 0.5-1mm). According to the predetermined process requirements, the outer dimensions of the valve body are preliminarily machined to be close to the design requirements, and at the same time, its surface roughness and other indicators are ensured to meet the basic conditions for subsequent welding and overall assembly. For example, the surface roughness value range is Ra3.2-Ra6.3μm, ensuring that the dimensional tolerance of each part of the valve body is controlled within ±0.3mm. By using a high-precision machining center, the excess material is accurately removed to ensure the dimensional accuracy of each part of the valve 2, laying the foundation for the subsequent valve 2 to be smoothly installed in the valve body and achieve good fit. The shaft diameter dimension tolerance of the valve is controlled within ±0.05mm, and the tolerance of other key contour dimensions is controlled within ±0.1mm;

[0038] S2: Spray high temperature resistant coating (700℃) on the outside of valve 2, upper valve body 1 and inside of lower valve body 3. High temperature resistant coating has good high temperature resistance, corrosion resistance and heat insulation performance. By spraying the coating evenly, it can play multiple roles in the subsequent welding process. On the one hand, it can reduce the impact of welding heat on the valve body and valve materials themselves to a certain extent, and reduce the generation of thermal stress; on the other hand, it can also protect the surface of the components to prevent erosion by external environmental factors during welding and subsequent use, and extend the service life of the water inlet ball valve. During the spraying process, pay attention to the distance between the spray gun and the workpiece surface. Keep it at about 20-30cm, and move the spray gun evenly to ensure that the coating thickness is uniform, generally controlled between 0.1-0.3mm, so that the coating can fully cover all parts;

[0039] S3: Install the valve 2 into the upper valve body 1 and the lower valve body 3, and fix the axial surfaces at both ends with the tooling. The positioning pins and clamping mechanism of the tooling must ensure a close fit with the axial surfaces at both ends of the valve, and the positioning accuracy must reach ±0.05mm. Adjust the sealing surface to the center. When the valve 2 is installed into the upper valve body 1 and the lower valve body 3, the role of the tooling is to firmly fix the axial surfaces at both ends of the valve 2 through its precise positioning and reliable clamping device, ensuring that the position of the valve 2 in the valve body is relatively stable. A dial indicator is provided in the tooling, and the sealing surface is carefully adjusted to the center position through the dial indicator. The error of the sealing surface adjustment is strictly controlled, and the error is strictly controlled within the allowable error range of ±0.02mm. This precision control requirement is extremely high, because the position accuracy of the sealing surface is directly related to the sealing performance of the water inlet ball valve after the subsequent welding is completed. Only by ensuring that the relative positions of each component are accurate and correct can we fully prepare for the subsequent high-quality welding work;

[0040] S4: Use a mechanical fixture to fix the upper valve body 1 and the lower valve body 3, and place the weld in a horizontal position, so as to facilitate the subsequent welding operation and ensure that the various parts are evenly stressed during the welding process, which is conducive to controlling deformation. A level is provided in the mechanical fixture, and the level tool is used to calibrate the weld position (the horizontal error is controlled within ±0.1°), and the weld is accurately placed in a horizontal position, which is convenient for the subsequent welding operation. The various parts are more evenly stressed during the welding process, which helps to better control the deformation of the valve body during the welding process, optimize the welding conditions from a mechanical point of view, and ensure the welding quality;

[0041] S5: The narrow gap welding gun is used for automatic welding at the bevel of the spherical part of the valve body. The advantages of narrow gap welding can effectively reduce the welding heat input, ensure the welding quality and reduce the impact on the valve body. Narrow gap welding can effectively reduce the welding heat input. Compared with traditional welding methods, it can greatly reduce the risk of valve body deformation caused by large amounts of heat input. At the same time, it can ensure the welding quality, so that the welding parts form a uniform, dense and firm weld, which meets the strict requirements of the water inlet ball valve for welding strength under the impact of high-pressure water flow for a long time. When performing this welding operation, it is necessary to pre-set precise welding parameters such as welding current, voltage, welding speed, etc. according to factors such as valve body material and thickness (for example, when high-strength alloy steel is selected, the welding current can be set at 200-300A, the voltage at 25-30V, and the welding speed is controlled at 20-30cm / min) to ensure that the welding process is stable and efficient, and the welding gun moves evenly along the bevel to achieve high-quality automatic welding operations;

[0042] S6: The same part of the valve body flange 4 and the spherical valve groove is welded automatically with narrow gap welding, and the rest of the groove is opened with a gas cutting device, with a groove angle of 17°, and manual welding is performed to further ensure the integrity and sealing of the flange 4 welding. In the automatic welding of the valve body spherical surface welding and the narrow gap welding of the valve body flange 4, the welding parameters are set according to the material and thickness of the valve body. When welding, select appropriate welding rods and perform manual welding according to the prescribed welding techniques. After each layer of welding is completed, slag removal and other treatments should be carried out in time to ensure that the welding surface is clean and tidy before continuing to the next layer of welding;

[0043] S7: During the whole welding process, the welding surface is locally heated and kept within a certain temperature range (150-200℃). The welding operation is performed with an automatic narrow gap welding gun. During the heating process of the sealing surface, a temperature sensor is installed to monitor the temperature in real time to ensure that the heating temperature is strictly within the set temperature range (for example, 150℃-200℃). This temperature range is a key condition that has been verified by a large number of experiments to ensure the welding quality and performance of the sealing surface;

[0044] S8: To reduce the deformation, the diagonal positions of the valve bodies on both sides are welded simultaneously. During the welding process, the deformation of the valve bodies needs to be monitored in real time. When it exceeds the allowable range, the welding parameters are adjusted in time or corrective measures are taken. This symmetrical welding method can effectively reduce the deformation of the large valve body caused by uneven thermal stress during welding. In the actual operation, two groups of welders need to be arranged on both sides of the water inlet ball valve, and start welding at the diagonal position at the same time. After welding a certain length, they move to the next diagonal position synchronously to continue welding, and so on.

[0045] S9: Turn valve 2 to a suitable position, clean the internal weld root, and remove possible defects at the weld root;

[0046] S10: After the water inlet ball valve is placed in an annealing furnace for annealing, the next process can be entered. The water inlet ball valve is placed in an annealing furnace for annealing according to a predetermined annealing process curve. The parameters of the annealing process curve are determined according to the valve body material to eliminate welding residual stress, stabilize the workpiece size, and further improve the overall performance of the water inlet ball valve.

[0047] The functional principle of the present invention can be explained through the following operation mode: select the upper valve body 1, lower valve body 3 and valve 2 of the water inlet ball valve that meet the design requirements, perform appearance and size inspection on them, ensure that there are no obvious defects, and then use rough processing equipment to rough process the upper valve body 1 and the lower valve body 3 according to the process requirements to achieve the specified roughness and dimensional tolerance range; use the machining center to process the remaining parts of the valve 2 except for the machining size of the sealing surface to ensure the dimensional accuracy of each part. Then, use a spray gun to evenly spray the pre-prepared high temperature resistant material on the outside of the valve 2 and the inside of the upper valve body 1 and the lower valve body 3;

[0048] Carefully install the valve 2 into the upper valve body 1 and the lower valve body 3, use the specially designed tooling to fix the axial surfaces at both ends of the valve 2 through the positioning and clamping devices of the tooling, and use a dial indicator or other measuring tool to adjust the sealing surface to the center position; then use a suitable mechanical fixture to firmly fix the upper valve body 1 and the lower valve body 3 from the outside, and calibrate with a level or other tool to ensure that the weld is accurately in a horizontal position;

[0049] Adjust the welding parameters of the narrow gap welding gun, such as welding current, voltage, welding speed, etc. (determine the specific parameter values ​​according to the material and thickness of the valve body), aim at the spherical welding groove of the valve body, start the automatic welding program, make the welding gun weld evenly along the groove, monitor the welding status in real time during the welding process to ensure the stable welding process;

[0050] For the same part of the valve body flange 4 as the spherical valve, automatic welding is performed according to the narrow gap welding parameter settings similar to the above; for the remaining parts, a large groove is first opened using gas cutting and other equipment, and then experienced welders use suitable electrodes to perform manual welding and repair welding according to the prescribed welding techniques. After each layer is welded, slag is removed and other treatments are performed before continuing to weld the next layer.

[0051] The sealing surface is locally heated by a heating device, and the temperature is monitored in real time by a temperature sensor. When the temperature reaches the appropriate temperature, the sealing surface is welded immediately using an automatic narrow gap welding gun according to the set welding trajectory and parameters. After welding, the appearance of the sealing surface is inspected to ensure that there are no welding defects.

[0052] Arrange two groups of welders to be located on both sides of the water inlet ball valve, and start welding at the diagonal position at the same time. After welding a certain length, move to the next diagonal position to continue welding, and repeat this cycle to ensure that the heat input on both sides is always relatively balanced during the welding process. Strictly control the deformation of the valve body. After welding a certain length, use measuring tools to detect the deformation of the valve body. If it exceeds the allowable range, adjust the welding parameters in time or take corresponding corrective measures;

[0053] After the automatic welding is completed, the flange 4 part is carefully inspected again, and the unevenness, missing welds and other parts found are manually welded to ensure the sealing and appearance quality of the flange 4; use a special tool to rotate the valve 2 to a position convenient for the root cleaning of the internal weld, and use carbon arc air gouging and other root cleaning methods to remove slag inclusions, unfused and other defects at the root of the internal weld. After root cleaning, the cleaned parts are polished and other treatments are performed; finally, the water inlet ball valve is placed in the annealing furnace as a whole, and the water inlet ball valve is placed in the annealing furnace for annealing according to the predetermined annealing process curve. After the treatment is completed, it is taken out and naturally cooled to room temperature.

[0054] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A narrow gap welding process for a water inlet ball valve of a pumped storage power station, characterized in that: The following steps are involved: S1: Rough machining is performed on the upper valve body (1) and the lower valve body (3) of the water inlet ball valve, and the valve (2) is machined except for the sealing surface with machining dimensions. According to the predetermined process requirements, the outer dimensions of the valve body are preliminarily machined to be close to the design requirements, while ensuring that its surface roughness and other indicators meet the basic conditions for subsequent welding and overall assembly, and ensuring that the dimensional tolerance of each part of the valve body is controlled within 0.3 mm; S2: spraying a high temperature resistant coating on the outside of the valve (2), the upper valve body (1) and the inside of the lower valve body (3), wherein the high temperature resistant coating has good high temperature resistance, corrosion resistance and heat insulation performance; S3: Install the valve (2) into the upper valve body (1) and the lower valve body (3), fix the axial surfaces at both ends with a tool, and adjust the sealing surface to the center; S4: Fix the upper valve body (1) and the lower valve body (3) using a mechanical clamp, and place the weld in a horizontal position; S5: Automatic welding with a narrow gap welding gun is used for the welding groove of the spherical part of the valve body; S6: The same part of the valve body flange (4) and the valve body spherical surface groove is welded automatically by narrow gap welding, and the remaining part is cut into a larger groove by gas cutting device and manually welded; S7: During the entire welding process, the surface to be welded is locally heated and maintained within a certain temperature range, and welding is performed using an automatic narrow gap welding gun; S8: To reduce deformation, the valve bodies on both sides are welded at the diagonal positions at the same time; S9: Turn the valve (2) to a suitable position and clean the internal weld; S10: Put the water inlet ball valve as a whole into the annealing furnace for annealing treatment before entering the next process.

2. According to claim 1, a narrow gap welding process for a water inlet ball valve of a pumped storage power station is characterized in that: When the valve (2) is installed in the upper valve body (1) and the lower valve body (3), after the axial surfaces at both ends are fixed by tooling, the error of adjusting the sealing surface to the center position is controlled within a preset allowable error range.

3. According to claim 1, a narrow gap welding process for a water inlet ball valve of a pumped storage power station is characterized in that: In the automatic welding of the valve body spherical surface welding and the narrow gap welding of the valve body flange (4), the welding parameters are set according to the material and thickness of the valve body.

4. According to claim 1, a narrow gap welding process for a water inlet ball valve of a pumped storage power station is characterized in that: When the sealing surface is locally heated, the temperature is monitored in real time by a temperature sensor, and the heating temperature must be within a set temperature range.

5. According to claim 1, a narrow gap welding process for a water inlet ball valve of a pumped storage power station is characterized in that: During the simultaneous welding of the diagonal positions of the valve bodies on both sides, it is necessary to detect the deformation of the valve bodies in real time, and to adjust the welding parameters or take corrective measures in a timely manner when the deformation exceeds the allowable range.

6. According to claim 1, a narrow gap welding process for a water inlet ball valve of a pumped storage power station is characterized in that: The water inlet ball valve is placed in an annealing furnace as a whole for annealing according to a predetermined annealing process curve, and the parameters of the annealing process curve are determined according to the material of the valve body.

7. A narrow gap welding process for a water inlet ball valve of a pumped storage power station according to claim 1, characterized in that: The function of the tooling is to firmly fix the axial surfaces at both ends of the valve (2) through its precise positioning and reliable clamping device, thereby ensuring that the position of the valve (2) in the valve body is relatively stable. A dial indicator is provided in the tooling, and the sealing surface is carefully adjusted to the center position through the dial indicator, so that the error of the sealing surface adjustment is strictly controlled.

8. The narrow gap welding process for the water inlet ball valve of a pumped storage power station according to claim 1 is characterized in that: A level is provided inside the mechanical fixture, and the position of the weld is calibrated using the level tool to place the weld accurately in a horizontal position.

9. A narrow gap welding process for a water inlet ball valve of a pumped storage power station according to claim 1, characterized in that: During the heating process of the sealing surface, a temperature sensor is provided to monitor the temperature in real time to ensure that the heating temperature is strictly within the set temperature range.

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