JPS622013A - Method of clamping nut and nut for clamping - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of tightening a flange portion of a high-pressure pipe or equipment with bolts and nuts, and a nut used for the tightening.

[Conventional technology]

Conventionally, when tightening a flange portion with bolts and nuts, a spanner or the like is generally used to tighten a plurality of bolts and nuts one by one as evenly as possible. In particular, when fluid leakage from the flange is a problem where high pressure is applied, or when relatively large diameter bolts and nuts are fastened, it is necessary to prevent uneven tightening and ensure sufficient tightening of each bolt. Traditionally, torque wrenches, bolt tensioners, etc. have been used to apply force.

[Problem that the invention seeks to solve]

The above-mentioned method of tightening bolts and nuts one by one with a spanner relies heavily on the operator's intuition, and therefore the uniformity of tightening varies greatly depending on the skill level of the operator.

In addition, with a torque wrench, the frictional resistance between each bolt and nut and the frictional resistance between the bottom surface of the nut and the flange are not the same, so even when tightened with a constant torque, the tension applied to each bolt is not necessarily constant. No.

In addition, one bolt tensioner is installed on each bolt to apply a predetermined tensile force to the bolt, but since the size of the bolt tensioner is large, even if a large number of bolt tensioners are prepared, it will not be possible to apply it. It is not possible to set all the bolts on the flange at the same time, so the bolts and nuts must be tightened alternately, and of course the bolt that is tightened first will then tighten the other bolts. As a result, the tension that was being applied is reduced, and it is difficult to apply uniform tension to all bolts.

The present invention solves the above problems and allows all bolts and nuts of the flange tightening part to be tightened at the same time with uniform force, preventing uneven tightening and problems caused by uneven tightening, and making tightening work easier. The object of the present invention is to provide a method for tightening bolts and nuts that does not require skill, and a hydraulic nut used for tightening.

[Means for solving problems]

The means of the present invention for solving the above problems is a nut tightening method in which a flange connection part is tightened using a plurality of bolts and nuts, each of the plurality of nuts being composed of two members forming a sealed hermetic chamber. , one member of each of the two members is screwed onto the bolt, hydraulic pressure is simultaneously applied to each of the sealed chambers, and each of the one member is moved while the bolt is extended, thereby tightening the other of the two members. Nut tightening characterized in that a gap is created between the members and a shim is inserted into each gap to completely fill the gap, and after the shim is inserted, the hydraulic pressure applied to the sealed chamber is released. In addition, a center hole to be screwed with a bolt, an annular groove formed at one end with a distance from the center hole and the inner surface, and a hydraulic pressure introduction hole communicating with the groove and opening to the outside are formed. a nut body, and a piston having an annular protrusion formed on one end surface that fits into the annular groove, and the annular groove and the annular protrusion form a sealed chamber through a sealing means. , the annular convex portion is slidable within the annular groove, and a shim is provided to fill a gap created between the nut body end surface and the piston end surface when hydraulic pressure is applied in the sealed chamber. This is a unique tightening nut.

[For production]

In the present invention, the tensile force applied to each bolt is F and the oil pressure in the sealed chamber is P. The relationship between the tensile force F and the oil pressure P is expressed by the following equation.

F=PX/(D2-d2)...
(11D: Piston convex outer diameter d: 〃 〃 Inner diameter When hydraulic pressure is applied to each sealed chamber at the same time, a tensile force F is applied to each bolt at the same time, each bolt expands, and the nut body screwed into each bolt moves. , gaps are generated between the end faces of the nut body and the piston. Shims are inserted into each gap to completely fill it.

〔Example〕

Next, the present invention will be described by way of examples with reference to the drawings.

FIG. 1 is a plan view of one embodiment of the present invention. In this figure, the flange 8 includes a plurality of bolts 2 and each bolt 2.
A plurality of nuts 1 are mounted for tightening. The nuts 1 have a hydraulic structure, each nut 1 is connected to a hydraulic pipe, the hydraulic pipe 4 is connected to a hydraulic pump 5, and the hydraulic pump 5 simultaneously connects each hydraulic nut 1 through a hydraulic pipe li. Supply hydraulic pressure.

FIG. 2 shows an embodiment of the hydraulic nut 1, and is a sectional view before and after tightening, with the left side showing the state before tightening and the right side showing the state after tightening.

The nut 1 consists of a nut body 6 and a piston 7 that are screwed together with the bolt 2. An annular groove constituting a sealed chamber 9 is formed in the end face of the nut body 6, and the sealed chamber 9 communicates with a hydraulic piping via a hydraulic pressure introduction hole 10. The piston 7 is formed with an annular protrusion 7a that fits into the sealed chamber 9.
The outer periphery of a and the inner periphery of the sealed chamber 9 are sealed against oil pressure by seal portions 8 and 8'.

To tighten the flange 3 using the nut 1 and bolt 2, insert the bolt 2 into the bolt hole 13 of the flange 3, combine the piston 7 with the nut body 6 to form a sealed chamber 9, and then tighten the nut body 6. Screw into bolt 2,
Bring to the tightened state shown on the left side of the figure. Next, the hydraulic pressure is transmitted from the hydraulic pump 5 through the hydraulic piping 4 (Fig. 1) to the hydraulic pressure introduction hole 1.
0 into the sealed chamber 9 (FIG. 2). This hydraulic pressure generates a pressing force against the flange 3 on the lower surface of the piston 7, and a reaction force of this pressing force applies tension to the bolt 2 via the nut body 6. Due to the generated tension, the bolt 2 stretches and a gap 12. occurs. After inserting a shim 11 having a thickness that completely fills this gap 12, when the hydraulic pressure is removed, the flange 3 remains uniformly tightened by all the bolts 2.

Furthermore, with reference to the drawings, the sealing portion of the sealed chamber 9 will be clearly explained by way of an example. Figure 3 shows the OI of the first embodiment.
The current value is Null. Seal part is O ring 20
．． 21 Backup spring 22゜28, OIJ ring presser foot 24. It consists of a pan head machine screw 25. Provide a notch in each of the seal parts 8.8' of the piston to insert the OIJ Song 0.21, and insert the backup rings 22 and 23°Q IJ Song 0.21 in this order from the piston side of the notch. . An O-ring retainer 24 that prevents the O-rings 20 and 21 from escaping to the sealed chamber 9 side is attached to the side of the piston 7, and a pan head machine screw 25 is screwed into the piston 7 to fix it.

The O-ring retainer 24 is a flat ring plate large enough to be inserted into the sealed chamber 7 and has approximately the same diameter as the convex portion of the piston 7.

Further, other embodiments of the seal portion will be described for O-ring types N[12 and Nn8 with reference to FIGS. 4 and 5. The sealing part consists of a notch into which the O-ring 20.21.0-ring 20.21 is inserted. In the NcZ type shown in FIG. 4, a notch is provided in the piston 7 on the small diameter side of the sealed chamber 9, that is, a portion of the seal portion 8, and a notch is provided in the nut body 6 on the portion of the seal portion 8'. The notch has a rectangular cross section and is provided in a ring shape from the sealing surface 8.8' of the body nut 6 or piston 7.

Insert Q IJ Song 0.21 into this notch. Figure 5 shows 01Jng 20.21. The insertion notch is N[12
It is provided symmetrically to the line between the type and the seal parts 8, 8', and the seal part 8 is attached to the nut body 6, and the seal part 8
A notch is provided in each piston 7 at the portion .

In other respects, type N[12NcL3 is the same.

Diaphragm type floors l and m2 based on Figures 6 and 7
The seal part will be explained. In order to attach the diaphragm 26 to the piston 7 side of the sealed chamber 9 of the nut body 6, sleeves 6' are provided on the outside and inside of the convex portion of the piston 7. The diaphragm 26 is stretched so as to cover the groove forming the sealed chamber 9 of the nut body 6. The diaphragm 26 is a ring-shaped disk whose inner and outer peripheries are brazed to the nut body 6 all around.

Next, the sleeves 6z69 are fitted into the outer periphery and the lower outer periphery of the nut body 6, respectively. In the positive 1 type shown in Fig. 6, the fitting part is screwed together. In the NcL2 type shown in Fig. 7, the fitting part has no screws and is a flat fitting. After fitting, the nut body 6 and the sleeve 6' are connected to the upper end of the sleeve 6' as shown in Fig. 6.7. Each fillet weld is made at the lower end of the sleeve 6'.

The cross section of the diaphragm 26 is designed so that the diaphragm 26 will not be damaged when hydraulic pressure is applied to the sealed chamber 9 and the piston 7 is activated.
For example, appropriate pleats are provided as shown in FIGS. 6 and 7. The top surface of the piston 7 is finished to match the unevenness of the folds of the diaphragm z6.

〔Effect of the invention〕

In the present invention, the tightening piece nuts have a double structure with sealed chambers, and the sealed chambers of a plurality of nuts are simultaneously applied to tighten the nuts through bolts, so that the following effects are achieved.

(Summer) All bolts can be tightened at the same time with uniform force, eliminating the occurrence of loose wires and leaks caused by loose wires.

(2) No cracking of the gasket due to one-sided wire. (3) The tightening force of the bolt can be controlled by the hydraulic pressure applied to the nut.

(4) All bolts are tightened at the same time, reducing work time.

(5) Tightening work is performed using hydraulic pressure, so no skill is required.

In particular, this method greatly improves reliability and workability as a method of tightening bolts used in high-temperature, high-pressure flanges.

[Brief explanation of drawings]

Fig. 1 is a plan view of an embodiment of the present invention, Fig. 2 is a sectional view of an embodiment of the invention, Fig. 8 is a detailed sectional view of the embodiment of the seal portion of Fig. 2, and Figs. 5, 6 and 7 are sectional views of four embodiments of the seal portion, respectively. 1...Natsuto, 2...Bolt. 3...Flange, 4...Hydraulic piping. 5...Hydraulic pump, 6...Nut body. 7... Piston, 7a... Annular convex portion. 8.8'... Seal part, 9... Sealed chamber. 10...!・Hydraulic pressure introduction hole. 2nd rI! J Figure 3 Figure 4 Figure 5

Claims (2)

[Claims] (1) In a nut tightening method in which a flange connection part is tightened using a plurality of bolts and nuts, each of the plurality of nuts is composed of two members constituting a sealed hermetic chamber, and one member of each of the two members are screwed onto the bolts, and hydraulic pressure is simultaneously applied to each of the sealed chambers to move each one of the members while extending the bolts to create a gap between each of the two members and the other member. and inserting a shim into each gap to completely fill the gap, and releasing the hydraulic pressure applied to the sealed chamber after inserting the shim. (2) A nut body that has a center hole that screws into the bolt, an annular groove formed on one end surface at a distance from the inner surface of the center hole, and a hydraulic pressure introduction hole that communicates with the groove and opens to the outside. , a piston having an annular convex portion formed on one end surface that fits into the annular groove; the annular groove and the annular convex portion form a sealed chamber via a sealing means; The annular convex portion is slidable in the groove, and is characterized by comprising a shim that fills a gap created between the nut body end surface and the piston end surface when hydraulic pressure is applied in the sealed chamber. Tightening nut.