JPH10249654A - Uniformly tightening method and device of multiple bolts and nuts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce any trouble of tightening operation, and simultaneously prevent even such a problem as pertaining to a fluid leakage from a connecting part, at the time of tightening a lot of bolts and nuts. SOLUTION: Plural pieces of branch hoses 17 are connected to a discharge hose 13 of a hydraulic pump 12, while each thread part of hydraulic bolt tensioners 10 is screwed in a tip part of each bolt 4, thereby making each hydraulic pressure from one of these branch hoses 17 act thereon at every bolt tensioner 10. With this constitution, respective nuts are tightened in a state that these nuts draw each tip part of these lots of bolts 4 tightened by hand each at a constant tension in the axial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of
The present invention relates to a method and apparatus for uniformly tightening nuts, and more particularly to a method and apparatus for uniformly tightening a large number of bolts and nuts connecting a case flange and a cover flange when assembling a diaphragm valve used in a nuclear power plant.

[0002]

2. Description of the Related Art Conventionally, a manual torque wrench has been used to tighten a large number (for example, 36) of bolts and nuts connecting a flange of a case of a diaphragm valve and a flange of a cover used in a nuclear power plant. I have.
In order to achieve uniform tightening, diagonal tightening is performed, and the tightening is performed in three stages of initial tightening, intermediate tightening, and final tightening.

[0003]

In the conventional method of uniformly tightening a large number of bolts and nuts, when assembling one diaphragm valve, the torque is checked three times for each of the 36 bolts and nuts. However, there is a problem that the tightening operation is very troublesome. In addition, since all the tightening operations are manually performed, it is difficult to apply the same axial tension to all bolts, and there is a problem that a bolt having a small axial tension is loosened and causes fluid leakage. .

SUMMARY OF THE INVENTION An object of the present invention is to reduce the trouble of the tightening operation when tightening a large number of bolts and nuts, and to apply substantially the same axial tension to all the bolts, so that fluid leakage from the joints can be achieved. It is an object of the present invention to provide a method and apparatus for uniformly tightening a large number of bolts and nuts, which can also prevent the problem described above.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a method for uniformly tightening a number of bolts and nuts according to the present invention comprises applying a constant tension in the axial direction to the tips of a number of bolts each having a nut manually tightened. Each nut is tightened in a pulled state.

In this way, it is possible to tighten the bolts and nuts without performing the work of checking the torque a plurality of times while checking the torque a plurality of times, and to apply the same axial tension to the bolts. This eliminates the problem that the bolt having a small axial tension is loosened and causes fluid leakage.

[0007] A plurality of branch hoses are connected to the discharge hose of the hydraulic pump, and the female thread of a hydraulic bolt tensioner is screwed to the tip of each bolt. It is preferable to obtain a constant axial tension by applying hydraulic pressure.

[0008] In this case, only one hydraulic pump is required for the drive means used to apply the same axial tension to the bolt, and the economy is secured.

According to the present invention, there is provided an apparatus for uniformly tightening a large number of bolts and nuts, comprising a hydraulic pump, a plurality of branch hoses connected to an oil discharge hose of the hydraulic pump, and a plurality of hydraulic pressure operated by hydraulic pressure from each branch hose. And a female screw having a cylindrical casing and a bolt rotatably and slidably fitted in the casing and having a nut screwed into a hand-tightened nut. And a cylindrical piston fitted between the casing and the bolt pulling shaft and pressing the bolt pulling shaft toward the other end by hydraulic pressure.

According to this device, after the female thread of the bolt tensioner is screwed to the tip of each bolt with the nut manually tightened, oil from each branch hose is supplied to the piston of each bolt tensioner. The same hydraulic pressure is applied to each piston, and all bolts can be pulled at a constant tension in the axial direction. By tightening each nut in this state, it is possible to tighten many bolts and nuts without having to check the torque several times for each bolt and nut. Since the directional tension can be applied, the problem that the bolt having a small axial tension is loosened and causes the fluid leakage is also solved.

A nut-rotating socket is fitted into one end of the casing, and a long slot is provided in the circumferential direction of the nut. A socket-rotating rod-fitting hole is formed in the peripheral wall of the socket at intervals in the circumferential direction. Is preferably provided. With this configuration, the nut can be rotated without inserting a spanner into the nut by inserting the socket rotation rod from the through-hole into the insertion hole of the socket and rotating the socket rotation rod. . Therefore, the tightening work becomes easy.

The hydraulic pump is preferably of an air-driven type. This makes it possible to easily perform uniform tightening of a large number of bolts and nuts in a place having an air pressure source.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. In the following description,
The upper and lower parts of the figure are referred to.

FIGS. 1 to 4 show a bolt and nut uniform tightening device according to the present invention which is used for attaching a disk-shaped cover (2) to a cylindrical case (1) of a diaphragm valve of a nuclear power plant. Is shown. Diaphragm valve case
(1) and cover (2) have flanges (1a) and (2a) respectively.
The flanges (1a) and (2a) are connected to each other by a number of flange bolts (4) and nuts (5) via a diaphragm sheet (3).

The bolt / nut uniform tightening device is attached to the tip of each flange bolt (4) and
(4) is composed of a hydraulic bolt tensioner (10) for tensioning the distal end portion with a constant tension in the axial direction, and a hydraulic pressure supply means (11) for supplying a constant hydraulic pressure to each bolt tensioner (10).

The hydraulic supply means (11) includes one air-driven hydraulic pump (12) and an oil discharge hose of the hydraulic pump (12).
One intermediate branch header (14) connected to (13) to branch oil into four intermediate branch hoses (15), and each intermediate branch hose
Four final branch headers connected to (15) to branch oil to the final branch hose (17) corresponding to each bolt tensioner (10)
(16). The connection between each hose (13) (15) (17) and each branch header (14) (16) and the connection between the final branch hose (17) and the bolt tensioner (10) are all hydraulic couplers (18)
Has been done through. Intermediate branch hoses (15), final branch headers (16), and final branch hoses (17)
All have the same shape. Therefore, the flow rates of the oil discharged from the final branch hoses (17) are all equal.

A pilot valve (19) for remote control and an axial force recorder (20) are connected to the hydraulic pump (12).

As shown in detail in FIGS. 2 and 3, the bolt puller (10) is connected to a hose connection (2) with the final branch hose.
2) a cylindrical casing (21) provided in a projecting shape, a piston (24) fitted vertically movably in the middle of the height of the casing (21), and a lower end of the casing (21). Fitted piston spring coil spring (25) and casing (21)
The bolt tension shaft (2) is inserted from the lower end of the bolt and inserted through the piston (24), and the upper end thereof projects from the piston (24).
6).

A bottomed cylindrical spring receiver (27) is screwed to the lower end of the casing (21). The coil spring (25)
The piston (24) is urged upward by being held by the spring receiver (27).

The casing (21) has a lower large-diameter portion (31) below the axis of the hose connection portion (22) and having a large inner diameter, and an upper end of the lower large-diameter portion (31) and having a smaller inner diameter. It comprises a small diameter portion (32) and an upper large diameter portion (33) connected to the upper end of the small diameter portion (32) and having an inner diameter larger than that.

At the upper end of the casing (21), a casing
A nut rotation socket (23) coaxial with (21) is fitted and supported by a step (35) formed between the upper large diameter part (33) and the small diameter part (32). On the inner periphery of the socket (23), mutually parallel inner surfaces (23a) for holding the mutually parallel outer surfaces of the nut (5) are formed. An annular groove (36) is provided near the upper end of the outer peripheral surface of the socket (23). A spring pin (28) is inserted into the annular groove (36) from a circular through hole (37) formed in the peripheral wall of the upper large diameter portion (33) of the casing (21), and the socket (23) is It is held by the casing (21) so as to be rotatable and not to move in the vertical direction. Near the lower end of the outer peripheral surface of the socket (23), a fitting hole (38) for fitting the tip of the socket rotating rod (29) is provided.
There are a total of four at intervals of °. And the casing (2
On the peripheral wall of the upper large-diameter portion (33) of (1), a long slot (39) is formed in the circumferential direction at a height corresponding to the fitting hole (38). The socket (23) is rotated by inserting the socket rotating rod (29) from the elongated hole (39) into the fitting hole (38) of the socket (23), and rotating the socket rotating rod (29),
The nut (5) can be turned. When the socket rotation rod (29) is rotated by using the end of the long hole (39), the nut (5) is rotated by 90 degrees.

The piston (24) has a large-diameter portion (41) fitted into the lower large-diameter portion (31) of the casing (21) and the casing (2).
The small diameter portion (42) fitted in the small diameter portion (32) of 1). When the hydraulic pressure is not applied, the upper end of the large-diameter portion (41) of the piston (24) and the lower large-diameter portion (31) of the casing (21) and the small-diameter portion ( 32) and a step (34) formed therebetween. The upper end of the outer peripheral portion of the large diameter portion (41) has been removed so that the casing (2
An oil introduction chamber (30) is formed between the step portion (34) of 1) and the large diameter portion (41). An oil introduction chamber (3
0) and an oil introduction passage (40) communicating the hose connection part (22). When the hydraulic pump (12) is operated, the oil flows through the hose connection part (22) and the oil introduction passage (40), and the oil enters the oil introduction chamber (3).
The piston (24) is moved downward by the pressure of this oil. Annular grooves (43) are provided on the outer periphery of the piston large diameter portion (42) and the inner periphery of the casing small diameter portion (32), respectively.
(44) is provided. An O-ring (45) and a backup ring (46) are fitted into these annular grooves (43) and (44), respectively, to ensure sealing between the piston (24) and the casing (21).

A bolt pulling shaft (26) projects upward from the piston (24) and is screwed to the tip of the flange bolt (4).
A cylindrical portion (48) inside (24) and a male thread portion (49) connected to the lower end thereof and having a lower end portion lower than the casing (21).
And the flange part (50) provided at the lower end of the male thread part (49)
And a cylindrical spacer portion (51) screwed to the male thread portion (49) and transmitting the downward force of the piston (24) to the flange portion (50).

The flange (50) is formed by fitting a short regular hexagonal column-shaped ring (52) to a prism (53) provided at the lower end of the male thread (49), and to the lower end of the prism (53). A nut (55) for preventing the ring (52) from coming off is screwed into the small-diameter external thread portion (54) provided continuously.

The lower end of the spacer portion (51) is
It is loosely fitted into a through-hole (27a) provided at the center of the bottom of the housing, and is brought into contact with the upper surface of the flange (50). When the bolt tensioner (10) is not used, there is a gap between the upper surface of the flange (50) and the lower surface of the spring receiver (27).
As shown in FIG. 3, there is a gap, and when using the bolt tensioner (10), the entire bolt tension shaft (26) is moved upward by the gap while rotating the bolt tension shaft (26). The female thread (47) can be screwed to the tip of the flange bolt (4).

When the nut (5) is tightened to the flange bolt (4) using the above-mentioned bolt tensioner (10), the following operation is performed.

First, the upper end surface of the casing (21) is
The socket (23) is fitted to the nut (5) while making contact with the lower surface of the flange (2a) of (1). Next, the flange portion (50) is rotated in the forward direction. Since the upward movement of the piston (24) is prevented, only the bolt pulling shaft (26) moves upward. The upper surface of the flange part (50) is the spring receiver (27)
The rotation of the flange portion (50) may be stopped when the flange portion (50) is brought into contact with the lower surface of the flange. As a result, the female thread (47) is screwed to the tip of the flange bolt (4), and the bolt tensioner (10)
Is held (see FIG. 4A). Next, the casing (2
Attach the final branch hose (17) to the hose connection part (22) of 1) via the hydraulic coupler (18). Perform the work up to this point for all flange bolts (4). Then, the switch of the hydraulic pump (12) is turned on. Oil bolt tensioner
(10) flows into the oil introduction chamber (30), and the casing (21)
(1) and the piston (24)
Press down. This allows the flange bolt (4)
Is pulled downward by an axial tension having a magnitude corresponding to the hydraulic pressure. Here, since the flow rates of the oil discharged from the final branch hoses (17) are all equal, the oil pressure resulting from introducing this oil into the oil introduction chamber (30) is also equal, and the flange bolts (4) Have the same magnitude of axial tension. In this state, the socket rotating rod
When the socket (23) is rotated by (29), the nut (5) comes into contact with the flange (1a) of the case (1) and the response changes.
At this point, the tightening is stopped, or the socket (23) is further rotated by a predetermined amount of rotation such as 10 °, 30 °, 45 °, or 60 ° with respect to this point, to thereby fix each flange bolt (4). All flange bolts (4) can be tightened while maintaining constant axial tension. The axial tension and tightening date and time of each flange bolt (4) are recorded on an axial force recorder (20).

FIG. 5 shows a modification of the hydraulic pressure supply means. The hydraulic supply means (56) shown in the figure includes one air-driven hydraulic pump (12), a branch hose (57) provided corresponding to each bolt tensioner (10), and a hydraulic pump (12). ) And one branch header (58) connected to the oil discharge hose (13) to branch the oil to each branch hose (57). The connection between each branch hose (57), each branch header (56), and the bolt tensioner (10) is all performed via a hydraulic coupler (18). The branch header (58) is formed in a ring shape having a diameter larger than the diameter of the flange (1a) of the diaphragm valve case (1).
(57) is connected. The branch hoses (57) are all of the same shape, and the flow rates of the oil discharged from the respective branch hoses (57) are all equal. When the flange bolt (4) is tightened, the branch header (58) is put on the case (1) of the diaphragm valve and positioned slightly below the flange (1a). Therefore, the length of the branch hose (57) can be reduced to about 40 to 50 cm,
The expansion of the branch hose (57) minimizes changes in hydraulic pressure that adversely affect tension. Also,
Unlike the hydraulic supply means (11) shown in FIG. 1, the branch is not divided into two stages, an intermediate stage and a final stage, so that the entire pipe can be made compact and the number of parts can be reduced.

FIG. 6 shows a circuit diagram of the hydraulic pressure supply means (11). The air-driven hydraulic pump (12) reciprocates the primary piston (61) by the pressure of the compressed air obtained by a compressed air generator (63) such as a compressor, for example. The oil is discharged by a secondary piston (62) which is provided integrally and is coaxial with the primary piston (61) and has a small diameter. Therefore, a predetermined hydraulic pressure can be easily obtained in a place having an air pressure source.

At the air inlet side of the hydraulic pump (12), a ball valve (64) for introducing or shutting off compressed air, an air filter (65) excluding a drain or the like in the compressed air, and a primary piston (61) ), A pressure reducing valve (66) for adjusting the air pressure, a pressure gauge (67) for reading the air pressure, and a lubricator (68) for preventing wear of the O-ring and the like in the hydraulic pump (12). .

When the air from the compressed air generator (63) pushes the primary piston (61) to the left in the drawing, the secondary piston (6)
2) moves to the left and the oil chamber (69) is moved by the secondary piston (62).
The oil inside is discharged.

A branch header (14) is connected to the oil outlet side of the hydraulic pump (12) via a hydraulic pressure switching valve (70) and an oil pressure gauge (71). After passing through the air filter (65), the compressed air passes through the pilot valve (1) through the pneumatic coupler (72).
9) is connected.

The specification of the bolt tensioner (10) in the above embodiment is a maximum tensile force of 6000 kgf (pressure 1).
000 kgf / cm ² ), normal tensile force 4200 kgf (pressure 700 kgf / cm ² ), and stroke 8 mm.
The specifications of the air-driven hydraulic pump (12) are such that the maximum discharge pressure is 1000 kgf / cm ² and the maximum discharge amount is 1.3 L / min.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing an apparatus for uniformly tightening a large number of bolts and nuts according to the present invention.

FIG. 2 is an exploded perspective view of the main part.

FIG. 3 is an enlarged sectional view of a bolt tensioner.

FIG. 4 is a cross-sectional view of a bolt tensioner showing a tightening procedure.

FIG. 5 is a perspective view schematically showing another embodiment of the apparatus for uniformly tightening a large number of bolts and nuts according to the present invention.

FIG. 6 is a circuit diagram of a hydraulic pressure supply unit.

[Explanation of symbols]

 (4) Flange bolt (5) Nut (10) Bolt puller (12) Hydraulic pump (13) Oil discharge hose (17) Final branch hose (21) Casing (23) Nut rotation socket (24) Piston (26) Bolt tension axis (29) Socket rotating rod (38) Socket rotating rod insertion hole (39) Slot (57) Branch hose

Claims (4)

[Claims] The nuts (5) are tightened in a state where the tips of a large number of bolts (4) each of which is manually tightened with a nut (5) are pulled in the axial direction at a constant tension. Method for uniformly tightening many bolts and nuts. 2. A plurality of branch hoses (17) and (57) are connected to a discharge hose (13) of a hydraulic pump (12),
At the end of (4), the female thread of hydraulic bolt tensioner (10)
By screwing (47) and applying hydraulic pressure from one branch hose (17) (57) for each bolt tensioner (10),
2. The method according to claim 1, wherein a constant axial tension is obtained. 3. A hydraulic pump (12) and a plurality of branch hoses (17) (57) connected to an oil discharge hose (13) of the hydraulic pump (12).
And a plurality of hydraulic bolt pullers (10) operated by hydraulic pressure from the branch hoses (17) and (57) .The bolt puller (10) includes a tubular casing (21) and a casing ( 21) rotatably and slidably fitted in the nut and nut
(5) a bolt pulling shaft (26) having at one end a female thread (47) screwed to the tip of a bolt (4),
A plurality of bolts each having a cylindrical piston (24) fitted between the casing (21) and the bolt pulling shaft (26) and pressing the bolt pulling shaft (26) toward the other end by hydraulic pressure. Nut uniform tightening device. 4. A nut rotation socket (23) is fitted into one end of the casing (21).
Circumferentially spaced socket rotary rod insertion holes (3
8. The device for uniformly tightening a large number of bolts and nuts according to claim 3, wherein the casing (21) is provided with a socket rotating rod insertion hole (39) which is long in the circumferential direction in the casing (21).