A critical break piston valve and method of manufacturing the same

Abstract

The present application relates to a kind of emergency stop piston valve and its manufacturing method, for manufacturing emergency stop piston valve, can not only be manufactured and assembled with reliable precision to each component of piston valve under the premise that the special working condition and use requirement of this safety piston valve assembly are fully considered, but also improve the tolerance of the micro deformation of each component of piston valve caused by temperature change, and further improve the precision of piston valve, so as to improve the stability of motor.

Description

Technical Field

[0001] This invention relates to the field of piston valve assembly and manufacturing technology, and in particular to an emergency shut-off piston valve and its manufacturing method. Background Technology

[0002] Both steam turbine generators and hydro turbine generators need to operate at their rated speeds. If they operate at excessive speeds for extended periods, it can cause permanent damage to the entire system, prevent shutdown, or even lead to major accidents such as equipment flying off. Therefore, it is essential to ensure that the equipment is 100% safe, stable, and reliable. Typically, a low-pressure turbine oil mechanical safety system and a high-pressure fire-resistant oil emergency shutdown safety system are in place to ensure that the generator does not operate at excessive speeds.

[0003] The interface between the low-pressure turbine oil mechanical safety system and the high-pressure fire-resistant oil emergency shutdown safety system is the emergency shutdown piston valve. It is controlled by the low-pressure turbine oil mechanical safety system to shut off the high-pressure fire-resistant oil emergency shutdown safety system. This shutdown valve serves as the last line of defense, requiring timely shutdown in emergencies while preventing accidental opening and unnecessary shutdowns. For a long time, its manufacturing and assembly methods have been challenging technical problems in the industry. Lower manufacturing precision increases the probability of accidental opening and unnecessary shutdowns, increasing production costs; higher manufacturing precision reduces service life and reduces the equipment's tolerance to micro-deformation caused by temperature changes, requiring more monitoring. Therefore, achieving a suitable processing and manufacturing precision has long been a problem that needs to be solved.

[0004] Meanwhile, since the piston valve needs to resist movement and prevent accidental movement, the control of each oil pressure and the selection of spring pressure are also urgent problems to be solved. Moreover, the selection of each oil pressure and spring pressure will directly affect the processing parameters required for each component, making it difficult to choose. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the problem of poor processing and manufacturing precision of piston valves in the prior art, which causes unstable working performance of piston valves, and to provide an emergency shut-off piston valve and a manufacturing method thereon, thereby improving the processing and manufacturing precision of piston valves.

[0006] To solve the above-mentioned technical problems, the present invention provides a method for manufacturing an emergency shut-off piston valve, comprising the following steps:

[0007] S1: Heat the billet to 580°C and hold the temperature for at least 30 minutes. Then heat the billet to 850°C, cool it to 700°C, hold it for 1 hour, and then heat it to 1000°C.

[0008] S2: The billet after the last heating in S1 is quenched in quenching oil for a maximum of 5 seconds, cooled to room temperature, and then tempered three times in a tempering furnace at a tempering temperature of 450℃.

[0009] S3: The blank after tempering in S2 is semi-finished on an inner circle machine to obtain a shell with a hardness of HRC60;

[0010] S4: The lathe tool is used for finishing the H62 copper blank. The speed of the lathe tool is at least 3 times the speed of the boring tool when boring the housing, to obtain the outer circle of the piston assembly. The outer circles of the housing and the piston assembly are then precision ground.

[0011] S5: Prepare the valve seat. Drill an axial central circular hole at the bottom of the valve seat. Drill rough holes on both sides of the valve seat to obtain high-pressure fire-resistant oil inlet holes and unpressurized oil return holes, which are connected to the central circular hole.

[0012] S6: First, use a reamer to finely ream the high-pressure fire-resistant oil inlet hole. During fine reaming, inject lubricating oil from the direction of the central circular hole at a flow rate of at least 1 liter per second. Continuously monitor the temperature difference of the lubricating oil before and after injection. If the temperature difference is greater than 5°C, increase the flow rate by 0.2 liters per second until the temperature difference is less than 5°C. Machining the pressureless return oil hole with the same cutting parameters, while simultaneously injecting lubricating oil into the central circular hole and the high-pressure fire-resistant oil inlet hole at a rate of 1 liter per second.

[0013] S7: Heat-treat the blank to form the adjustment ring. Heat the blank to 1100°C and cool it to 950°C. Forge all six sides at least 100 times on a forging press. The forging speed is such that the interval between each forging is increased by 2 seconds. The minimum forging temperature is 800°C to obtain the adjustment ring.

[0014] In one embodiment of the present invention, the boring and milling parameters in S3 are: boring tool speed 1000 r / min, feed rate 0.02 mm / r, and milling depth 0.05 mm.

[0015] In one embodiment of the present invention, the rotational speed of the coarse drilling bit in S5 is 1000 r / min, and the feed rate is 0.05 mm / r; the rotational speed of the fine reamer in S6 is 500 r / min.

[0016] In one embodiment of the present invention, after precision reaming by S6, the inner surface of the valve seat is boring. The boring bar rotates at 1500 r / min, the feed rate is 0.01 mm / r, the boring depth is 0.05 mm, and a machining allowance of 0.05 mm is retained for precision grinding. A diamond grinding wheel is used, and the grinding wheel rotates at 5000 r / min.

[0017] In one embodiment of the present invention, the outer circle of the adjusting ring obtained in S7 is precision turned. During the precision turning process, the cutting tool speed is 1500 r / min, the feed rate is 0.01 mm / r, and the turning depth is 0.02 mm, so that the surface roughness of the outer circle of the adjusting ring is less than that of the inner surface of the valve seat, and the distance between the two is between 0.005-0.01 mm.

[0018] In one embodiment of the present invention, when the adjusting ring and the valve seat are assembled, their relative moving speed is 10 mm / s.

[0019] In one embodiment of the present invention, the adjusting screw passes through the valve seat and presses against the adjusting ring. When adjusting the preload, each of the two adjusting screws rotates 180 degrees and is screwed in alternately until the predetermined preload is reached. The preload deviation on both sides must be less than 100N.

[0020] To address the aforementioned problems, an emergency shut-off piston valve is also provided, manufactured using the aforementioned method. This piston valve includes an adjusting ring, a valve seat, a housing, a piston assembly, and an adjusting screw.

[0021] The valve seat is coaxially connected to the housing, the piston assembly and the adjusting ring are disposed inside the housing, and the adjusting screw passes through the valve seat and presses against the adjusting ring.

[0022] The emergency shut-off piston valve also includes a disc spring assembly disposed within the housing. The valve seat has a first receiving cavity, and the bottom of the adjusting ring coaxially abuts against the first receiving cavity. The adjusting ring has a second receiving cavity, and the bottom of the disc spring assembly coaxially abuts against the second receiving cavity. The bottom of the second receiving cavity has a receiving groove, and a one-way thrust bearing is coaxially disposed within the receiving groove. The inner wall of the central circular hole has two coaxially disposed annular grooves, and a guide band and a sealing ring are respectively disposed within the two annular grooves.

[0023] In one embodiment of the present invention, a support ring is also coaxially provided in the second receiving cavity, the support ring being disposed between the disc spring assembly and the one-way thrust bearing.

[0024] In one embodiment of the present invention, a top cover is further included, the top cover being disposed at one end of the housing, and the top cover being provided with a screw-in pipe joint.

[0025] The technical solution of the present invention has the following advantages compared with the prior art:

[0026] The manufacturing method of the emergency shut-off piston valve described in this invention, under the premise of fully considering the special working conditions and usage requirements of this safety piston valve assembly, not only manufactures and assembles each component of the piston valve with reliable precision, but also improves the tolerance of each component of the piston valve to the micro-deformation caused by temperature changes, thereby improving the precision of the piston valve and thus improving the stability of the motor. Attached Figure Description

[0027] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0028] Figure 1 This is a schematic diagram of the piston valve described in this invention.

[0029] Figure 2 yes Figure 1 A structural schematic diagram of a partial cross-sectional view along the BB direction.

[0030] Instruction manual drawing reference numerals: 1. Adjusting screw; 2. Nut; 3. Valve seat; 4. Guide band; 5. Sealing ring; 6. Adjusting ring; 7. One-way thrust bearing; 8. Disc spring assembly; 9. Socket head cap screw; 10. Standard spring washer; 11. Socket head cap screw; 12. Screw-in pipe fitting assembly; 13. Sealing ring; 14. Support ring; 15. Piston assembly; 16. Housing; 17. Sealing ring; 18. Top cover; 19. Screw; 20. Screw-in pipe fitting; 21. O-ring seal; 22. Screw-in pipe fitting; 23. O-ring seal; 24. High-pressure fire-resistant oil inlet hole; 25. Central circular hole; 26. Unpressurized return oil hole; 27. Piston rod. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0032] Example

[0033] In one embodiment of the present invention, as referred to Figure 1 and 2 As shown, a method for manufacturing an emergency shut-off piston valve according to the present invention, for manufacturing the emergency shut-off piston valve, includes the following steps:

[0034] S1: Prepare the billet. First, remove the burrs from the outer circle of the billet on a lathe. Then, heat treat the billet by heating it to 580°C and holding it at that temperature for at least 30 minutes. Then, heat the billet to 850°C, cool it to 700°C, hold it at that temperature for 1 hour, and then heat it to 1000°C.

[0035] S2: The billet after the last heating in S1 is quenched in quenching oil for a maximum of 5 seconds, cooled to room temperature, and then tempered three times in a tempering furnace at a tempering temperature of 450℃.

[0036] S3: The blank after the tempering treatment in S2 is semi-finished on the inner circle on a boring machine to obtain the shell 16 with a hardness of HRC60, so as to achieve sufficient wear resistance.

[0037] S4: A diamond turning tool is used to finish the H62 copper blank. The rotation speed of the turning tool is at least three times the rotation speed of the boring tool when boring the housing, to obtain the outer circle of the piston assembly 15. The outer circles of the housing 16 and the piston assembly 15 are then precision ground.

[0038] S5: Prepare valve seat 3. Drill a central circular hole 25 in the axial direction at the bottom of valve seat 3. Drill rough holes on both sides of valve seat 3 to obtain high-pressure fire-resistant oil inlet hole 24 and unpressurized oil return hole 26. High-pressure fire-resistant oil inlet hole 24 is at the bottom and unpressurized oil return hole 26 is at the top. The two are parallel to each other and pass through the central circular hole 25. Under normal circumstances, the piston rod 27 of piston assembly 15 blocks this central circular hole 25. Both high-pressure fire-resistant oil inlet hole 24 and unpressurized oil return hole 26 are equipped with screw-in pipe joint assembly 12 and sealing ring 13.

[0039] S6: First, use a reamer to finely ream the high-pressure fire-resistant oil inlet hole 24. During fine reaming, inject lubricating oil from the direction of the central circular hole 25 at a flow rate of at least 1 liter per second. Continuously monitor the temperature difference of the lubricating oil before and after injection. If the temperature difference is greater than 5°C, increase the flow rate by 0.2 liters per second until the temperature difference is less than 5°C. Machining the pressureless return oil hole with the same cutting parameters, while simultaneously injecting lubricating oil into the central circular hole 25 and the high-pressure fire-resistant oil inlet hole 24 at a rate of 1 liter per second. The valve seat 3 and the adjusting ring 6 need to be able to slide smoothly relative to each other when the pressure is triggered and the alarm is activated. However, under normal conditions, the contact surfaces of the valve seat 3 and the adjusting ring 6 usually do not slide for 3-5 years because the steam turbine or hydro generator will operate stably most of the time.

[0040] S7: Heat-treat the billet forming the adjustment ring 6. Heat the billet of the adjustment ring 6 to 1100℃ and cool it to 950℃. Then, forge each of the six sides at least 100 times on a forging press. The forging speed is such that the interval between each forging is increased by 2 seconds to match the gradual decrease in temperature and the slower speed of lattice balance. The minimum forging temperature is 800℃ to obtain the adjustment ring 6.

[0041] In one embodiment of the present invention, the boring and milling parameters in S3 are: boring tool speed 1000 r / min, feed rate 0.02 mm / r, and milling depth 0.05 mm.

[0042] In one embodiment of the present invention, the rotational speed of the coarse drilling bit in S5 is 1000 r / min, and the feed rate is 0.05 mm / r; the rotational speed of the fine reamer in S6 is 500 r / min.

[0043] In one embodiment of the present invention, as referred to Figure 1 As shown, after precision reaming by S6, the inner surface of valve seat 3 is boring. The boring bar speed is 1500 r / min, the feed rate is 0.01 mm / r, the boring depth is 0.05 mm, and a machining allowance of 0.05 mm is retained for precision grinding. A diamond grinding wheel is used, and the grinding wheel speed is 5000 r / min.

[0044] In one embodiment of the present invention, the outer circle of the adjusting ring 6 obtained in S7 is precision turned. During the precision turning process, the cutting tool speed is 1500 r / min, the feed rate is 0.01 mm / r, and the turning depth is 0.02 mm, so that the surface roughness of the outer circle of the adjusting ring 6 is less than that of the inner surface of the valve seat 3, and the distance between the two is between 0.005-0.01 mm.

[0045] In one embodiment of the present invention, when the adjusting ring 6 and the valve seat 3 are assembled, their relative moving speed is 10 mm / s.

[0046] In one embodiment of the present invention, as referred to Figure 1 and 2 As shown, the adjusting screw 1 passes through the valve seat 3 and presses against the adjusting ring 6. When adjusting the preload, each of the two adjusting screws 1 rotates 180 degrees and is screwed in alternately until the predetermined preload is reached. The preload deviation on both sides must be less than 100N.

[0047] In one embodiment of the present invention, as referred to Figure 1 and 2 As shown, a method for manufacturing an emergency shut-off piston valve is also provided. The valve includes an adjusting ring 6, a valve seat 3, a housing 16, a piston assembly 15, and an adjusting screw 1. Specifically, it includes a housing 16 and a valve seat 3 connected by an internal hexagonal head screw 9. A standard spring washer 10 is provided between the internal hexagonal head screw 9 and the housing 16. A disc spring assembly 8 is disposed within the housing 16. The valve seat 3 has an adjusting ring 6 and a circular first receiving cavity. The bottom of the adjusting ring 6 coaxially abuts against the first receiving cavity. The adjusting ring 6 also has a circular second receiving cavity. The bottom of the disc spring assembly 8 coaxially abuts against the second receiving cavity and extends out of the second receiving cavity. The bottom of the second receiving cavity has a circular receiving groove, and a one-way thrust bearing 7 is coaxially disposed within the receiving groove.

[0048] The inner wall of the central circular hole 25 is provided with two coaxial annular grooves. The two annular grooves are respectively provided with a guide belt 4 and a sealing ring 5. The guide belt 4 is used to guide the piston rod 27, and the sealing ring 5 is close to the piston rod 27.

[0049] In one embodiment of the present invention, as referred to Figure 1 and 2 As shown, a support ring 14 is also coaxially provided in the second receiving cavity, and the support ring 14 is disposed between the disc spring assembly 8 and the one-way thrust bearing 7.

[0050] In one embodiment of the present invention, as referred to Figure 1 and 2 As shown, it also includes multiple adjusting screws 1 and nuts 2, as well as an upper cover 18. The adjusting screws 1 pass through the valve seat 3 and abut against the adjusting ring 6. The upper cover 18 is disposed at one end of the housing 16 and is connected by an internal hexagonal head screw 11. A sealing ring 17 is provided between the housing 16 and the upper cover 18. The upper cover 18 is provided with a screw-in pipe joint 20 and an O-ring seal 21 for sealing the screw-in pipe joint 20. The housing 16 is also provided with a screw-in pipe joint 22 and an O-ring seal 23.

[0051] In one embodiment of the present invention, as referred to Figure 1 and 2 As shown, it also includes an upper cover 18, which is disposed at one end of the housing 16. The upper cover 18 is provided with a screw-in pipe joint 20 and an O-ring seal 21.

[0052] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for manufacturing an emergency shut-off piston valve, characterized in that, The emergency shut-off piston valve includes an adjusting ring, valve seat, housing, piston assembly, and adjusting screw. The valve seat is coaxially connected to the housing, the piston assembly and the adjusting ring are disposed inside the housing, and the adjusting screw passes through the valve seat and presses against the adjusting ring. The emergency shut-off piston valve also includes a disc spring assembly disposed within the housing. The valve seat has a first receiving cavity, and the bottom of the adjusting ring coaxially abuts against the first receiving cavity. The adjusting ring has a second receiving cavity, and the bottom of the disc spring assembly coaxially abuts against the second receiving cavity. The bottom of the second receiving cavity has a receiving groove, and a one-way thrust bearing is coaxially disposed within the receiving groove. The inner wall of the central circular hole has two coaxially disposed annular grooves, and a guide band and a sealing ring are respectively disposed within the two annular grooves. The manufacturing method of this emergency shut-off piston valve includes the following steps: S1: Heat the billet to 580°C and hold the temperature for at least 30 minutes. Then heat the billet to 850°C, cool it to 700°C, hold it for 1 hour, and then heat it to 1000°C. S2: The billet after the last heating in S1 is quenched in quenching oil for a maximum of 5 seconds, cooled to room temperature, and then tempered three times in a tempering furnace at a tempering temperature of 450℃. S3: The blank after tempering in S2 is semi-finished on an inner circle machine to obtain a shell with a hardness of HRC60; S4: The lathe tool is used for finishing the H62 copper blank. The speed of the lathe tool is at least 3 times the speed of the boring tool when boring the housing, to obtain the outer circle of the piston assembly. The outer circles of the housing and the piston assembly are then precision ground. S5: Prepare the valve seat. Drill an axial central circular hole at the bottom of the valve seat. Drill rough holes on both sides of the valve seat to obtain high-pressure fire-resistant oil inlet holes and unpressurized oil return holes, which are connected to the central circular hole. S6: First, use a reamer to finely ream the high-pressure fire-resistant oil inlet hole. During fine reaming, inject lubricating oil from the direction of the central circular hole at a flow rate of at least 1 liter per second. Continuously monitor the temperature difference of the lubricating oil before and after injection. If the temperature difference is greater than 5°C, increase the flow rate by 0.2 liters per second until the temperature difference is less than 5°C. Machining the pressureless return oil hole with the same cutting parameters, while simultaneously injecting lubricating oil into the central circular hole and the high-pressure fire-resistant oil inlet hole at a rate of 1 liter per second. S7: Heat-treat the blank to form the adjustment ring. Heat the blank to 1100°C and cool it to 950°C. Forge all six sides at least 100 times on a forging press. The forging speed is such that the interval between each forging is increased by 2 seconds. The minimum forging temperature is 800°C to obtain the adjustment ring. When the adjusting ring and the valve seat are assembled, their relative moving speed is 10 mm / s; The adjusting screw passes through the valve seat and presses against the adjusting ring. When adjusting the preload, each of the two adjusting screws rotates 180 degrees and screws in alternately until the predetermined preload is reached. The preload deviation on both sides must be less than 100N.

2. The manufacturing method of an emergency shut-off piston valve according to claim 1, characterized in that, The boring and milling parameters in S3 are: boring bar speed 1000 r / min, feed rate 0.02 mm / r, and milling depth 0.05 mm.

3. The method for manufacturing an emergency shut-off piston valve according to claim 1, characterized in that, The rotational speed of the roughing drill bit in S5 is 1000 r / min, and the feed rate is 0.05 mm / r; the rotational speed of the reamer in S6 is 500 r / min.

4. The manufacturing method of an emergency shut-off piston valve according to claim 1, characterized in that, After precision reaming with S6, the inner surface of the valve seat is boring. The boring bar speed is 1500 r / min, the feed rate is 0.01 mm / r, the boring depth is 0.05 mm, and a machining allowance of 0.05 mm is retained for precision grinding. A diamond grinding wheel is used, and the grinding wheel speed is 5000 r / min.

5. A method for manufacturing an emergency shut-off piston valve according to claim 1, characterized in that, The outer circle of the adjusting ring obtained by S7 is precision turned. During the precision turning process, the cutting tool speed is 1500 r / min, the feed rate is 0.01 mm / r, and the turning depth is 0.02 mm, so that the surface roughness of the outer circle of the adjusting ring is less than that of the inner surface of the valve seat, and the distance between the two is between 0.005-0.01 mm.

6. A method for manufacturing an emergency shut-off piston valve according to claim 1, characterized in that, The second receiving cavity is also coaxially provided with a support ring, which is disposed between the disc spring assembly and the one-way thrust bearing.

7. A method for manufacturing an emergency shut-off piston valve according to claim 1, characterized in that, It also includes a top cover, which is disposed at one end of the housing and is provided with a screw-in pipe fitting.

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