A nuclear reactor mechanical seal nut synchronous screwing device and method

Abstract

The present invention relates to the technical field of on-site maintenance of nuclear power plants, and specifically discloses a device and method for synchronously screwing nuts of nuclear reactor mechanical seals. In the device, a plurality of screw holes are opened on the support plate, and a shaft is provided in each screw hole, the number and position distribution of the screw holes correspond to the number and position of HALF mechanical seal ball nuts; the sleeve is fixed on the shaft through a bearing; the driving component fixed on the support plate is connected to the sleeve through a transmission component, and the sleeve can be driven to rotate along the shaft through the driving component; the front end of the sleeve is a head structure that matches the spherical nut. The device and method can solve the installation of the HALF nut of the reactor pressure vessel thermocouple confidential seal, and realize the synchronous screwing and pre-tightening of a single nut or multiple nuts in a narrow space on site, so as to improve the work efficiency and maintenance quality of the installation of the top thermocouple mechanical seal, and reduce the radiation dose received by the maintenance personnel.

Description

Technical Field

[0001] The invention belongs to the technical field of on-site maintenance of nuclear power plants, and in particular relates to a synchronous screwing device and method for a nuclear reactor mechanical seal nut. Background Art

[0002] The function of the thermocouple mechanical seal of the nuclear reactor pressure vessel is to seal the thermocouple cluster tube and the pressure vessel top cover. It is one of the weakest links in the primary pressure boundary. During the operation of the unit, it bears the high temperature, high pressure and water flow impact of the primary boric acid water. Once the pressure boundary leaks, it will directly lead to irreversible serious consequences such as shutdown, reactor shutdown, and decommissioning. According to the historical operation information of nuclear power plants at home and abroad, the sealing structure has failed many times and caused leakage of the main system. Summary of the invention

[0003] The purpose of the present invention is to provide a nuclear reactor mechanical seal nut synchronous screwing device and method to solve the installation problem of the HALF nut of the reactor pressure vessel thermocouple mechanical seal, so as to improve the work efficiency and maintenance quality of the reactor top thermocouple mechanical seal installation and reduce the radiation dose received by the maintenance personnel.

[0004] The technical solution of the present invention is as follows: a nuclear reactor mechanical seal nut synchronous screwing device, the device includes a plurality of sleeves, a support plate, a bearing, a shaft, a driving component and a transmission component, wherein a plurality of screw holes are opened on the support plate, and a shaft is provided in each screw hole, and the number and position distribution of the screw holes correspond to the number and position of the HALF mechanical seal ball nut; the sleeve is fixed on the shaft through a bearing; the driving component fixed on the support plate is connected to the sleeve through a transmission component, and the sleeve can be driven to rotate along the shaft through the driving component; the front end of the sleeve is a head structure matching the spherical nut.

[0005] The transmission component includes a large gear and a small gear. The large gear is fixedly connected to the rear end of the sleeve, and the small gear is fixed to the output shaft of the driving component. The small gear is meshed with the large gear, and the driving component drives the small gear, thereby driving the sleeve fixed to the large gear to rotate.

[0006] The driving component includes a motor, a reducer and an encoder, wherein the front end of the reducer is fixedly connected to the support plate, and the output shaft passes through the support plate and is connected to the transmission component; the rear end input part of the reducer is connected to the motor, and an encoder is provided at the tail of the motor.

[0007] The shaft is a circular rotating body and is provided with steps and grooves. The bearing is installed on the shaft through a shaft elastic retaining ring. The step on the shaft and the shaft elastic retaining ring are used to limit the movement of the bearing in the shaft axis direction.

[0008] The device also includes a shell, which is a shell structure with through holes at the front end matching the number and position of the sleeve. The support plate is installed in the shell and fixed so that the sleeve extends out of the through holes at the front end of the shell; and a back cover is installed at the rear end of the shell to confine the support plate and the layout connected to it in the cavity formed by the shell and the back cover.

[0009] The shell is also provided with a handle, and the handle is installed on the shell through a handle support plate.

[0010] The driving component is connected to the controller via a cable, and the controller can drive the driving component to move in a torque mode or a distance mode.

[0011] A method for synchronously screwing a nuclear reactor mechanical seal nut, the method comprising:

[0012] Install gap calibration blocks of equal thickness on the left and right sides of the gap between the first HALF structure and the second HALF structure;

[0013] Pre-tighten the ball nut using a sleeve so that the first HALF structure and the second HALF structure clamp the gap calibration block;

[0014] Take out the gap calibration blocks in the left and right gaps of the first HALF structure and the second HALF structure;

[0015] The sleeve is driven to screw the ball nut in the forward direction, and when the screwing torque of the driving motor reaches the set value, the driving motor stops working, and the mechanical seal ball nut is synchronously tightened and fixed.

[0016] In the process of pre-tightening the ball nut, the controller is used to drive the motor to rotate in the positive direction in the torque mode, thereby driving the sleeve to pre-tighten the ball nut in the positive direction.

[0017] When taking out the gap calibration block in the left and right gaps of the first HALF structure and the second HALF structure, it is necessary to use the distance mode to drive the motor through the controller to rotate in the reverse direction for a certain distance, so that the gap between the first HALF structure and the second HALF structure is increased, and the gap calibration block is taken out; then, the distance mode is used to drive the motor through the controller to rotate in the positive direction, driving the sleeve to screw the ball nut in the positive direction, and when the screwing torque of the drive motor reaches the set value, the drive motor stops working, and the mechanical sealing ball nut is synchronously tightened and fixed.

[0018] The remarkable effect of the present invention is that the nuclear reactor mechanical seal nut synchronous screwing device and method described in the present invention can solve the installation of the HALF nut of the reactor pressure vessel thermocouple confidential seal, and realize the synchronous screwing and pre-tightening of a single nut or multiple nuts in a small space on site, so as to improve the work efficiency and maintenance quality of the installation of the reactor top thermocouple mechanical seal and reduce the radiation dose received by maintenance personnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic structural diagram of a synchronous screwing device for a nuclear reactor mechanical seal nut according to the present invention;

[0020] Figure 2 It is an exploded view of a synchronous screwing device for a nuclear reactor mechanical seal nut according to the present invention;

[0021] Figure 3 This is a diagram showing the use status of a synchronous screwing device for a nuclear reactor mechanical seal nut according to the present invention;

[0022] In the figure: 1. housing; 2. sleeve; 3. support plate; 4. handle; 5. handle support plate; 6. back cover; 7. bearing; 8. large gear; 9. elastic retaining ring for shaft; 10. screw; 11. shaft; 12. small gear; 13. reducer; 14. motor; 15. encoder; 16. gap calibration block; 17. first HALF structure; 18. ball nut; 19. second HALF structure; 20. cable; 21. controller. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] like Figures 1 to 3As shown, a nuclear reactor mechanical seal nut synchronous screwing device includes a sleeve 2, a support plate 3, a bearing 7, a shaft 11, a reducer 13 and a motor 14, wherein a plurality of screw holes are opened on the support plate 3, and the position layout and number of the screw holes on the support plate 3 correspond to the position and number of the HALF mechanical seal ball nut 18; a shaft 11 is installed in the screw hole of the support plate 3, wherein the shape of the shaft 11 is a circular rotating body, and a step and a groove for installing a shaft elastic retaining ring 9 are provided on the shaft 11, and the bearing 7 is connected to the shaft elastic retaining ring 9 by the shaft elastic retaining ring 9. The ring 9 is installed on the shaft 11, and the step on the shaft 11 and the shaft elastic ring 9 are used to limit the movement of the bearing 7 in the axial direction of the shaft 11; the sleeve 2 is made of a cylindrical barrel structure made of high-strength metal materials such as chromium-molybdenum steel, and the inner wall of its front end is a head structure that matches the spherical nut to be screwed. The rear end of the sleeve is connected to the large gear 8 through a polygonal or key-matching structure and fixed by bolts; the inner circle structure of the rear end of the sleeve 2 matches the outer circle of the bearing 7, and the sleeve 2 is fixed to the bearing 7 by screws 10 evenly distributed in the circumferential direction of the sleeve, so that The sleeve 2 can rotate along the shaft 11; the motor 14 with an encoder 15 installed at the tail is installed on the rear end surface of the support plate 3 through the reducer 13, and the output shaft of the reducer 13 passes through the support plate 3, and a small gear 12 is installed on the output shaft of the reducer 13 at the front end of the support plate 3, and the small gear 12 is meshed with the large gear 8; each sleeve 2 is connected to a set of driving components to achieve separate control of the sleeve 2; the shell 1 has a through hole at the front end that matches the number and position of the sleeve 2, and the shell 1 is inserted into the support plate 3 as a whole, so that the sleeve 2 extends out of the through hole of the housing 1, and a rear cover 6 is installed at the rear end of the housing 1 to install the support plate 3 and the components connected thereto into the cavity formed by the housing 1 and the rear cover 6; the handle 4 is installed on the housing 1 through the handle support plate 5, and the device can be conveniently operated and moved by the handle 4; the housing 1, the support plate 3, the handle 4, the handle support plate 5 and the rear cover 6 are made of light metal materials such as aviation aluminum; the controller 21 is connected to the motor 14 through the cable 20, and the controller 21 can be used to drive the motor to rotate forward or reverse in torque mode or distance mode;

[0025] A method for synchronously screwing a nuclear reactor mechanical seal nut, the method specifically comprising:

[0026] S1. Install gap calibration blocks of equal thickness on the left and right sides of the gap between the first HALF structure and the second HALF structure;

[0027] S2. Pre-tighten the ball nut of the mechanical seal;

[0028] Match the angle of the sleeve in the synchronous screwing device with the ball nut to be screwed and insert it, use the controller to drive the motor to rotate in the positive direction in torque mode, drive the sleeve to screw and pre-tighten the ball nut in the positive direction, so that the first HALF structure and the second HALF structure clamp the gap calibration block, and realize that the gaps on the left and right sides of the first HALF structure and the second HALF structure are equal;

[0029] S3. Tighten the ball nut of the mechanical seal synchronously;

[0030] S3.1, taking out the gap calibration blocks in the left and right gaps of the first HALF structure and the second HALF structure;

[0031] The controller uses a distance mode to drive the motor to rotate in the reverse direction for a certain distance, so that the gap between the first HALF structure and the second HALF structure is increased, and the gap calibration block is taken out;

[0032] S3.2. Tighten the ball nut of the mechanical seal synchronously;

[0033] The controller uses the distance mode to drive the motor to rotate in the positive direction, driving the sleeve to screw the ball nut in the positive direction, and when the screwing torque of the drive motor reaches the set value, the drive motor stops working, and the mechanical seal ball nut is synchronously tightened and fixed. The theoretical clearance value of the left and right sides of the HALF fixture is the same.

Claims

1. A method for synchronously screwing a nut of a nuclear reactor mechanical seal, characterized in that: The method includes: Install gap calibration blocks of equal thickness on the left and right sides of the gap between the first HALF structure and the second HALF structure; Pre-tighten the ball nut using a sleeve so that the first HALF structure and the second HALF structure clamp the gap calibration block; Take out the gap calibration blocks in the left and right gaps of the first HALF structure and the second HALF structure; The sleeve is driven to screw the ball nut forward, and when the screwing torque of the driving motor reaches the set value, the driving motor stops working, and the mechanical seal ball nut is synchronously tightened and fixed; When taking out the gap calibration block in the left and right gaps of the first HALF structure and the second HALF structure, it is necessary to drive the motor to rotate in the reverse direction for a certain distance through the controller in the distance mode, so that the gap between the first HALF structure and the second HALF structure is increased, and the gap calibration block is taken out; then, the controller drives the motor to rotate in the forward direction in the distance mode, driving the sleeve to screw the ball nut forward, and when the screwing torque of the drive motor reaches the set value, the drive motor stops working, and the mechanical seal ball nut is synchronously tightened and fixed; The device in the method for synchronously screwing a nuclear reactor mechanical seal nut comprises a plurality of sleeves (2), a support plate (3), a bearing (7), a shaft (11), a driving component and a transmission component, wherein a plurality of screw holes are formed on the support plate (3), and a shaft (11) is provided in each screw hole, wherein the number and position distribution of the screw holes correspond to the number and position of a HALF mechanical seal ball nut (18); the sleeve (2) is fixed on the shaft (11) via a bearing (7); the driving component fixed on the support plate (3) is connected to the sleeve (2) via a transmission component, and the sleeve (2) can be driven to rotate along the shaft (11) via the driving component; and the front end of the sleeve (2) is a head structure matching the ball nut (18).

2. A method for synchronously tightening a nuclear reactor mechanical seal nut according to claim 1, characterized in that: In the process of pre-tightening the ball nut, the controller is used to drive the motor to rotate in the positive direction in the torque mode, thereby driving the sleeve to pre-tighten the ball nut in the positive direction.

3. A method for synchronously tightening a nuclear reactor mechanical seal nut according to claim 1, characterized in that: The transmission component comprises a large gear (8) and a small gear (12); the large gear is fixedly connected to the rear end of the sleeve (2); and the small gear (12) is fixed to the output shaft of the driving component; the small gear (12) is meshed with the large gear (8), and the driving component drives the small gear (12), thereby driving the sleeve (2) fixed to the large gear (8) to rotate.

4. A method for synchronously tightening a nuclear reactor mechanical seal nut according to claim 1, characterized in that: The driving component comprises a motor (14), a reducer (13) and an encoder (15), wherein the front end of the reducer (13) is fixedly connected to the support plate (3), and the output shaft passes through the support plate (3) and is connected to the transmission component; the rear input part of the reducer (13) is connected to the motor (14), and the encoder (15) is provided at the tail of the motor (14).

5. A method for synchronously tightening a nuclear reactor mechanical seal nut according to claim 1, characterized in that: The shaft (11) is a circular rotating body and is provided with a step and a groove. The bearing (7) is mounted on the shaft (11) via a shaft elastic retaining ring (9). The step on the shaft (11) and the shaft elastic retaining ring (9) are used to limit the movement of the bearing (7) in the axial direction of the shaft (11).

6. A method for synchronously tightening a nuclear reactor mechanical seal nut according to claim 1, characterized in that: The device further comprises a housing (1), the housing being a shell structure having a front end with through holes matching the number and position of the sleeve (2); a support plate (3) is inserted into the housing (1) and fixed so that the sleeve (2) extends out of the through holes at the front end of the housing (1); and a rear cover (6) is installed at the rear end of the housing (1) so that the support plate (3) and the connected arrangement thereof are confined within a cavity formed by the housing (1) and the rear cover (6).

7. A method for synchronously tightening a nuclear reactor mechanical seal nut according to claim 6, characterized in that: The housing (1) is also provided with a handle (4), and the handle (4) is mounted on the housing (1) via a handle support plate (5).

8. A method for synchronously tightening a nuclear reactor mechanical seal nut according to claim 1, characterized in that: The driving component is connected to a controller (21) via a cable (20), and the driving component can be driven to move in a torque mode or a distance mode via the controller (21).

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