Method for realizing automatic welding of hard alloy surfacing of special-shaped bushing of steam turbine main steam valve assembly
The automated welding of the main steam valve bushing of the steam turbine is achieved by plasma spraying technology, which solves the problems of traditional manual argon arc welding, improves welding efficiency and quality, and reduces costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HARBIN TURBINE
- Filing Date
- 2023-12-29
- Publication Date
- 2026-05-15
AI Technical Summary
When overlaying Stellite alloy onto the main steam valve bushing of a steam turbine, traditional manual argon arc welding is difficult, resulting in poor weld consistency, easy defects, complex procedures, and low efficiency.
Automated welding is achieved by using plasma spraying technology. By adjusting the position and parameters of the plasma spraying gun and combining it with the arc voltage tracking mode, a reasonable welding sequence for the end face and inner circle of the irregular bushing is realized, ensuring welding quality and efficiency.
It improved welding efficiency, reduced labor costs, ensured product quality, reduced welding defects, and increased production efficiency and product lifespan.
Smart Images
Figure CN117733490B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of automated welding technology, specifically to a method for automated welding of special-shaped bushings for main steam valve assemblies of steam turbines using hard alloy overlay welding. Background Technology
[0002] The main steam valve bushing of the steam turbine is a critical component of the equipment, used to ensure steam flow control, sealing, and protection of key components to maintain system reliability and performance. Therefore, Stellite alloy needs to be overlaid on some parts of the product to enhance its service life and strength. Stellite alloy is a hard alloy resistant to various types of wear, corrosion, and high-temperature oxidation. Due to the product's structure and the fact that Stellite alloy welding needs to be performed under high-temperature conditions, traditional manual argon arc welding is difficult and cannot guarantee weld consistency and quality, resulting in low welding efficiency. Furthermore, due to the material's special properties, welding Stellite alloy is prone to defects such as cracks. Since the inner bore, end faces, and beveled sides of this product all require Stellite alloy, the welding process is extremely complex and difficult to complete. Summary of the Invention
[0003] The purpose of this invention is to solve the problems of complex welding process for Stellite alloy overlay welding on turbine main steam valve bushings, and poor weld consistency and easy welding defects when using manual argon arc welding to overlay Stellite alloy on turbine main steam valve bushings. Therefore, this invention provides a method for automated welding of hard alloy overlay welding on irregular bushings of turbine main steam valve assembly.
[0004] The method for automated welding of special-shaped bushings for main steam valve assemblies of steam turbines using hard alloy overlay welding is carried out according to the following steps:
[0005] Step 1: Process the irregular bushing according to the drawing to obtain the irregular bushing;
[0006] Step 2: Place the irregular bushing into the electric heating furnace for preheating. After preheating, take it out and place it in the center of the turntable, ensuring that it is 90° perpendicular to the turntable, and use the clamps to clamp it.
[0007] Step 3: Adjust the position of the plasma spraying gun head to align with the end face of the shaped bushing, and ensure that the plasma arc is centered on the inner and outer circles on one side of the end face of the shaped bushing; then, in a non-arc simulation, check and confirm the relative position of the gun body and the shaped bushing while the welding gun swings back and forth and the turntable rotates.
[0008] Step 4: After starting welding, turn on the arc voltage tracking mode and deposit Stellite alloy on the end face of the irregular bushing. Observe the weld formation during the welding process and adjust the welding parameters in time. Stop the arc when the welding height reaches the standard, grind and extinguish the arc, remove the irregular bushing from the turntable, and place it in the furnace for heat treatment.
[0009] Step 5: After the heat treatment is completed, the inner circle of the weld overlay bushing is machined. After the machining is completed, the inner circle of the bushing is inspected for defects and then preheated in an electric furnace.
[0010] Step 6: Remove the shaped bushing from the electric furnace, place it in the center of the turntable with the welded end face facing upwards, and then use the clamps to hold it in place. Rotate the turntable to a 90° horizontal position. Use a medium-sized inner wall plasma spray welding gun to spray weld Stellite alloy onto the inner circle of the shaped bushing, and adjust its position to ensure that the weld pool is exactly on the bottom side of the shaped bushing after the start of welding. Perform spiral welding from the inside out. After welding, put the shaped bushing back into the furnace for heat treatment.
[0011] Step 7: Machin the heat-treated irregular bushing as a whole until it meets the relevant dimensional requirements of the drawing.
[0012] The beneficial effects of this invention are:
[0013] To address the problems existing in the prior art, improve work efficiency, and ensure quality, this invention employs plasma spraying welding for the irregularly shaped bushings of the main steam valve assembly of steam turbines. Taking advantage of the low heat load on the plasma spraying substrate, the parts are less prone to deformation, and the process is stable, resulting in a dense coating and high bonding strength, a reasonable welding and processing sequence is adopted for the locations requiring Stellite product overlay welding, thereby improving production efficiency and reducing costs.
[0014] This invention utilizes automated welding equipment, which will significantly improve actual production efficiency. Furthermore, automated welding will reduce labor costs and improve product quality.
[0015] This invention provides a method for automated welding of special-shaped bushings for main steam valve assemblies of steam turbines using hard alloy overlay welding. Attached Figure Description
[0016] Figure 1 This is a dimensional drawing of the irregular bushing before welding in Example 1;
[0017] Figure 2 The dimensions achieved after welding the end face of the irregular bushing in Example 1;
[0018] Figure 3 This is a dimensional drawing of the integrally machined irregular bushing in Example 1;
[0019] Figure 4 This is a schematic diagram of a traditional welding structure. Detailed Implementation
[0020] Specific Implementation Method 1: This implementation method for automated welding of special-shaped bushings for turbine main steam valve assemblies using hard alloy overlay welding is carried out according to the following steps:
[0021] Step 1: Process the irregular bushing according to the drawing to obtain the irregular bushing;
[0022] Step 2: Place the irregular bushing into the electric heating furnace for preheating. After preheating, take it out and place it in the center of the turntable, ensuring that it is 90° perpendicular to the turntable, and use the clamps to clamp it.
[0023] Step 3: Adjust the position of the plasma spraying gun head to align with the end face of the shaped bushing, and ensure that the plasma arc is centered on the inner and outer circles on one side of the end face of the shaped bushing; then, in a non-arc simulation, check and confirm the relative position of the gun body and the shaped bushing while the welding gun swings back and forth and the turntable rotates.
[0024] Step 4: After starting welding, turn on the arc voltage tracking mode and deposit Stellite alloy on the end face of the irregular bushing. Observe the weld formation during the welding process and adjust the welding parameters in time. Stop the arc when the welding height reaches the standard, grind and extinguish the arc, remove the irregular bushing from the turntable, and place it in the furnace for heat treatment.
[0025] Step 5: After the heat treatment is completed, the inner circle of the weld overlay bushing is machined. After the machining is completed, the inner circle of the bushing is inspected for defects and then preheated in an electric furnace.
[0026] Step 6: Remove the shaped bushing from the electric furnace, place it in the center of the turntable with the welded end face facing upwards, and then use the clamps to hold it in place. Rotate the turntable to a 90° horizontal position. Use a medium-sized inner wall plasma spray welding gun to spray weld Stellite alloy onto the inner circle of the shaped bushing, and adjust its position to ensure that the weld pool is exactly on the bottom side of the shaped bushing after the start of welding. Perform spiral welding from the inside out. After welding, put the shaped bushing back into the furnace for heat treatment.
[0027] Step 7: Machin the heat-treated irregular bushing as a whole until it meets the relevant dimensional requirements of the drawing.
[0028] The beneficial effects of this implementation method are:
[0029] In order to solve the problems existing in the prior art, improve work efficiency, and ensure quality, this embodiment adopts plasma spraying welding for the special-shaped bushing of the main steam valve assembly of the steam turbine. Based on the advantages of plasma spraying, such as low heat exposure of the substrate, easy deformation of parts, stable process, dense coating and high bonding strength, the location where Stellite products need to be overlaid is selected by adopting a reasonable welding and processing sequence to improve production efficiency and reduce costs.
[0030] This implementation method utilizes automated welding equipment, which will significantly improve actual production efficiency. Furthermore, automated welding will reduce labor costs and improve product quality.
[0031] Specific Implementation Method Two: The difference between this implementation method and Specific Implementation Method One is that in step 1, the machining allowance in the length direction of the irregular bushing is ensured to be greater than 15mm.
[0032] The other steps are the same as in Specific Implementation Method 1.
[0033] Specific Implementation Method 3: The difference between this implementation method and Specific Implementation Method 1 or 2 is that the preheating temperature of the irregular bushing in step 2 is 300-350℃.
[0034] The other steps are the same as in Specific Implementation Method 1 or 2.
[0035] Specific Implementation Method Four: The difference between this implementation method and Specific Implementation Methods One to Three is that: before welding the end face of the irregular bushing, the plasma spraying gun is cleaned and it is confirmed that the powder feeding gas, shielding gas and ion gas are unobstructed.
[0036] The other steps are the same as those in Specific Implementation Methods One to Three.
[0037] Specific Implementation Method 5: The difference between this implementation method and Specific Implementation Methods 1 to 4 is that the arc is stopped in step 4 when the welding height reaches 40mm.
[0038] The other steps are the same as those in Specific Implementation Methods One through Four.
[0039] Specific Implementation Method Six: The difference between this implementation method and Specific Implementation Methods One to Five is that in step 5, the inner circle of the welded irregular bushing is machined to...
[0040] The other steps are the same as those in Specific Implementation Methods 1 to 5.
[0041] Specific Implementation Method Seven: The difference between this implementation method and Specific Implementation Methods One to Six is that the preheating temperature of the irregular bushing in step 5 is 300-350℃.
[0042] The other steps are the same as those in Specific Implementation Methods 1 to 6.
[0043] Specific Implementation Method Eight: The difference between this implementation method and Specific Implementation Methods One to Seven is that in step 6, the inner circle of the irregular bushing is integrally spray-welded to ensure that the inner circle can be machined to a size smaller than [the specified size].
[0044] The other steps are the same as those in Specific Implementation Methods 1 to 7.
[0045] Specific Implementation Method Nine: The difference between this implementation method and Specific Implementation Methods One to Eight is that the welding parameters in steps 4 and 6 are as follows: welding current is 160A, welding speed is 70mm / min, powder feeding amount is 75%; left side stay is 0.2s, right side stay is 0.2s, oscillation speed is 1000mm / min, oscillation amplitude is 15mm; ion gas flow rate is 4L / min, powder feeding gas flow rate is 2.5L / min, shielding gas flow rate is 20L / min; diameter is set to 100mm, direction is selected as positive; voltage is set to 24V.
[0046] The other steps are the same as those in Specific Implementation Methods 1 to 8.
[0047] Specific Implementation Method 10: The difference between this implementation method and Specific Implementation Methods 1 to 9 is that in step 6, spiral welding is performed from the inside out to ensure a processing allowance of 2mm on one side.
[0048] The other steps are the same as those in Specific Implementation Methods 1 to 9.
[0049] The beneficial effects of the present invention are verified using the following embodiments:
[0050] Example 1: A method for automated welding of special-shaped bushings for main steam valve assemblies of steam turbines using hard alloy overlay welding, comprising the following steps:
[0051] Based on the location of the Stellite alloy to be welded onto the irregular bushing, the welding and processing sequence is determined first. The bushing end face is welded first to ensure that the head position and the bevel contain Stellite. After heat treatment, the inner hole position is machined to ensure that the inner hole is smooth to meet the requirements of subsequent welding. After heat treatment again, it can be transferred to machining for precision machining of the entire irregular bushing.
[0052] Step 1: Machining according to the special-shaped bushing drawing, ensuring that the machining allowance in the length direction of the special-shaped bushing is greater than 15mm, to obtain the special-shaped bushing;
[0053] According to the product's dimensions before welding (e.g.) Figure 1 As shown in the figure, determine the welding height of the end face to be welded.
[0054] Step 2: Place the irregular bushing into the electric heating furnace and preheat it at a temperature of 350°C. After preheating, take it out and place it in the center of the turntable, ensuring that it is 90° perpendicular to the turntable, and use the clamps to clamp it.
[0055] Step 3: Adjust the position of the plasma spraying gun head to align with the end face of the shaped bushing, and ensure that the plasma arc is centered on the inner and outer circles on one side of the end face of the shaped bushing; then, in non-arc simulation mode, check and confirm the relative position of the gun body and the shaped bushing while the welding gun swings back and forth and the turntable rotates; set the welding parameters on the operation panel as shown in Table 1 below.
[0056] Table 1: Welding process parameters;
[0057] Welding current Welding speed Welding powder quantity Stay on the left Stay on the right Swing speed Swing amplitude 160A 70mm / min 75％ 0.2s 0.2s 1000mm / min 15mm Ionized gas Send powder Protective gas Diameter setting Direction selection Voltage setting 4L / min 2.5L / min 20L / min 100mm positive 24V
[0058] After starting the welding process, the welding torch is swung back and forth to meet the width requirements of Stellite alloy for the end face and the bevel.
[0059] Before welding the end face of the irregular bushing, clean the plasma spraying gun and ensure that the powder gas, shielding gas and ion gas are unobstructed to avoid the impact of foreign objects, insufficient gas and water leakage on the welding quality of the product during the welding process.
[0060] Step 4: After starting welding, activate the arc voltage tracking mode and deposit Stellite alloy onto the end face of the irregular bushing. Observe the weld formation during welding and adjust welding parameters as needed. Stop the arc when the welding height reaches 40mm (e.g., Figure 2 As shown in the figure, after grinding and finishing the arc, the special-shaped bushing is removed from the turntable and placed in the furnace for heat treatment.
[0061] Step 5: After heat treatment, the inner circle of the welded special-shaped bushing is machined to φ92.76mm. Other parts are not machined yet to prevent the welding deformation of the product due to excessive heat input during the subsequent welding process, which would fail to meet the final processing size requirements. After the processing is completed and the inner circle of the special-shaped bushing is found to be free of defects, it is preheated in an electric furnace at a temperature of 350℃.
[0062] Step 6: Remove the shaped bushing from the electric furnace and place it in the center of the turntable with the welded end face facing upwards. Then, use the clamps to hold it in place and rotate the turntable to a 90° horizontal position. Use a medium-sized inner wall plasma spray welding gun to spray weld Stellite alloy onto the inner circle of the shaped bushing, ensuring that the inner circle can be machined to less than φ88.76mm. Adjust its position to ensure that the weld pool is exactly on the bottom side of the shaped bushing after the welding starts. Perform spiral welding from the inside out, ensuring a machining allowance of 2mm on each side. After welding, put the shaped bushing back into the furnace for heat treatment.
[0063] Step 7: Machin the heat-treated irregular bushing as a whole until it meets the relevant dimensional requirements of the drawing (e.g., ...). Figure 3 (As shown).
Claims
1. A method for automated welding of special-shaped bushings for main steam valve assemblies of steam turbines using hard alloy overlay welding, characterized in that... This method is performed in the following steps: Step 1: Process the irregular bushing according to the drawing to obtain the irregular bushing; Step 2: Place the irregular bushing into the electric heating furnace for preheating. After preheating, take it out and place it in the center of the turntable, ensuring that it is 90° perpendicular to the turntable, and use the clamps to clamp it. Step 3: Adjust the position of the plasma spraying gun head to align with the end face of the shaped bushing, and ensure that the plasma arc is centered on the inner and outer circles on one side of the end face of the shaped bushing; then, in a non-arc simulation, check and confirm the relative position of the gun body and the shaped bushing while the welding gun swings back and forth and the turntable rotates. Step 4: After starting welding, turn on the arc voltage tracking mode and deposit Stellite alloy on the end face of the irregular bushing. Observe the weld formation during the welding process and adjust the welding parameters in time. Stop the arc when the welding height reaches the standard, grind and extinguish the arc, remove the irregular bushing from the turntable, and place it in the furnace for heat treatment. Step 5: After the heat treatment is completed, the inner circle of the weld overlay bushing is machined. After the machining is completed, the inner circle of the bushing is inspected for defects and then preheated in an electric furnace. Step 6: Remove the shaped bushing from the electric furnace, place it in the center of the turntable with the welded end face facing upwards, and then use the clamps to hold it in place. Rotate the turntable to a 90° horizontal position. Use a medium-sized inner wall plasma spray welding gun to spray weld Stellite alloy onto the inner circle of the shaped bushing, and adjust its position to ensure that the weld pool is exactly on the bottom side of the shaped bushing after the start of welding. Perform spiral welding from the inside out. After welding, put the shaped bushing back into the furnace for heat treatment. Step 7: Machin the heat-treated irregular bushing as a whole until it meets the relevant dimensional requirements of the drawing.
2. The method for automated welding of special-shaped bushings for turbine main steam valve assembly according to claim 1, characterized in that... In step 1, ensure that the machining allowance in the length direction of the irregular bushing is greater than 15mm.
3. The method for automated welding of special-shaped bushings for turbine main steam valve assembly according to claim 1, characterized in that... In step 2, the preheating temperature of the irregular bushing is 300-350℃.
4. The method for automated welding of special-shaped bushings for turbine main steam valve assembly according to claim 1, characterized in that... Before welding the end face of the irregular bushing, clean the plasma spraying gun and ensure that the powder gas, shielding gas and ion gas are unobstructed.
5. The method for automated welding of special-shaped bushings for turbine main steam valve assembly according to claim 1, characterized in that... In step 4, the arc is stopped when the welding height reaches 40mm.
6. The method for automated welding of special-shaped bushings for turbine main steam valve assembly according to claim 1, characterized in that... In step 5, the inner circle of the welded special-shaped bushing is machined to φ92.76mm.
7. The method for automated welding of special-shaped bushings for turbine main steam valve assembly using hard alloy overlay welding according to claim 1, characterized in that... In step 5, the preheating temperature of the irregular bushing is 300-350℃.
8. The method for automated welding of special-shaped bushings for turbine main steam valve assembly according to claim 1, characterized in that... In step 6, the inner circle of the irregular bushing is spray-welded as a whole to ensure that the inner circle can be machined to a size smaller than φ88.76mm.
9. The method for automated welding of special-shaped bushings for turbine main steam valve assembly according to claim 1, characterized in that... The welding parameters in steps 4 and 6 are as follows: welding current 160A, welding speed 70mm / min, powder feed rate 75%; 0.2s pause on the left side, 0.2s pause on the right side, oscillation speed 1000mm / min, oscillation amplitude 15mm; ion gas flow rate 4L / min, powder feed gas flow rate 2.5L / min, shielding gas flow rate 20L / min; diameter set to 100mm, direction selected as positive; voltage set to 24V.
10. The method for automated welding of special-shaped bushings for turbine main steam valve assembly according to claim 1, characterized in that... In step 6, spiral welding is performed from the inside out, ensuring a machining allowance of 2mm on each side.