JPH0384296A - Double link type hinge type bellows coupling - Google Patents

Abstract

PURPOSE:To provide enough buckling strength against an internal pressure by providing an intermediate link mechanism the central part of which is secured and which is provided on both sides with pins engaged with oblong holes formed in respective hinge arms and movable along the longitudinal direction of a bellows. CONSTITUTION:The central part of a hinge type bellows coupling is supported by a control ring 2 throughout the periphery of the central part of a bellows 1, and the central part is secured to a link arm 10. Further, an intermediate mechanism wherein pins 11 and 12 mounted to the ends both sides of the bellows 1 are engaged with oblong holes 13 and 14 formed in hinge structures 6 and 7 is provided. This constitution completely constrains the central part of the bellows even in a displacement state of the bellows 1 to ensure high buckling strength.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a bellows joint that absorbs mutual bending displacement between pipes or between a pipe and a container caused by thermal expansion, vibration, and the like.

[Conventional technology]

Conventionally, bending displacement-absorbing hinge types have been used in various plant piping systems such as nuclear, chemical, and petroleum plants, and high-temperature duct systems in jet engines, to absorb deformation caused by thermal expansion and vibration, and to make routing more compact. Bellows joints are often used.

Figure 3 shows a conventional example of a hinged bellows joint;
The figure shows a bellows column squirm, 21.2
7 is bellows, 22.23.28.29 is flange, 2
4 is a hinge pin, and 25.26 is a hinge arm.

In the figure, flanges 22 and 23 for piping connection are provided on both sides of a bellows 21, and a hinge structure consisting of hinge arms 25 and 26 of the same length that can rotate around a hinge pin 24 is the flange. 2
A pair is fixed at 2 and 23 facing each other at 180 degrees.

When a relative bending displacement occurs at both ends of the bellows joint due to thermal expansion or vibration of the piping, the bellows joint deforms as shown by the dotted line to absorb the bending displacement.

[Problem to be solved by the invention]

In order to make piping routing more compact with a conventional hinge-type bellows joint, it is necessary to increase the displacement angle that can be absorbed by one bellows, and a long bellows with a large number of ridges is used.

On the other hand, from the viewpoint of strength, as shown in FIG. 4, the bellows 27 causes a characteristic buckling called column squirm due to internal pressure, so it is necessary to prevent this.

The critical pressure that causes buckling is inversely proportional to the square of the number of bellows ridges. That is, the greater the number of ridges, the lower the strength against buckling. Therefore, it is not possible to simply increase the number of ridges in order to increase the amount of displacement absorbed by the bellows, and a limit naturally arises in terms of buckling strength.

The present invention is intended to solve the above problems, and an object of the present invention is to provide a double link hinge type bellows joint that has a large amount of bending displacement absorption and has sufficient buckling strength against internal pressure.

[Means to solve the problem]

The present invention provides a hinge-type bellows joint in which both ends of the bellows are each fixed by at least one set of hinge arms, and each hinge arm is connected at the center by a hinge bin to absorb bending displacement in a predetermined direction. a support means for supporting the center portion circumferentially; and pins on both ends that are fixed to the center portion and movable along the longitudinal direction of the bellows by fitting into elongated holes provided in each hinge arm. The invention is characterized by comprising an intermediate link mechanism having an intermediate link mechanism.

[Effect]

In the present invention, the central part of a hinged bellows joint is supported by a control ring over the circumference of the central part of the bellows, the central part is fixed to a link arm, and the pins provided at both ends are fitted into elongated holes provided in the hinge structure. By providing the combined intermediate link mechanism, it is possible to completely restrain the central portion of the bellows even when the bellows is in a displaced state, thereby ensuring large buckling strength.

〔Example〕

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a double link hinge type bellows joint according to the present invention, and FIG. 1A is a side view and FIG.
B) is a plan view, FIG. 2C is an enlarged view of the elongated hole, and FIG. 2 is a diagram for explaining the deformed state of the bellows joint. In the figure, 1 is a bellows, 2 is a control ring, 3.4 is a flange, 5 is a hinge structure, 6.7 is a hinge arm, 8 is a hinge bin, 9 is an intermediate link structure, 10 is a link arm, 11
．． 12 is a link pin, and 13.14 is a long hole.

In the figure, flanges 3 and 4 for piping connection are connected to both ends of a bellows 1. Further, the control ring 2 is provided at the center of the bellows 1 in the longitudinal direction so as to be orthogonal to the central axis x-x' of the bellows 1.

The hinge structure 5 (11th fflB) is composed of hinge arms 6 and 7 of the same length that are freely rotatably joined by a hinge pin 8, with the hinge pin 8 located at the longitudinal center of the bellows 1 and the control ring 2. A pair of hinge structures 5 are fixed to the side surfaces of the flanges 3 and 4 facing each other by 180 degrees so as to coincide with the center of the side surfaces of the flanges 3 and 4.

Further, a pair of intermediate link structures 9 (FIG. 1B) provided on each of the pair of hinge structures 5 are composed of a link arm 10 and link pins 11 and 12 provided at both ends thereof. The center of the link arm 10, which corresponds to the center of the distance, is fixed to the side surface of the control ring 2. Further, the link pins 11 and 12 are fitted into elongated holes 13 and 14 provided in the hinge arms 6 and 7.

When this bellows joint is in the undeformed state shown by the solid line in FIG. , move within the elongated holes 13 and 14 in a direction away from the hinge bin 8. When this bellows joint deforms to the designed bending angle 2θ, the long holes 13 and 14
It stops moving when it comes into contact with the outer surface of the

In this way, the control ring 2 is integrated with the intermediate link structure 9, and the intermediate link structure 9 is fitted with the outer hinge structure 5 via the link pins 11 and 12 at both ends, so that the present bellows joint The control ring 2 is completely restrained both in the undeformed state and in the deformed state where bending displacement is applied.

In Fig. 2, the intersections of the central axis x-x' of this bellows joint in an undeformed state and the bellows side surfaces of the flanges 3 and 4 are designated as A and B, and the center of the control ring 2 on the central axis X-X' is D, then in the deformed state with the design bending angle 2θ, B and D move to B' and D', respectively, and the central axis x- of the intermediate link structure 9 in the undeformed state
The centers P and Q of link pins 11 and 12 projected onto x' move to P' and Q', respectively.

Here, if the distance AP' between P' and the flange 3 is a, and the distance PQ between the link pins 11 and 12 is 2a, then in the designed bending state, P'D'=a=AP', and the right angle The triangle AP'O and the right triangle D'P'0 are congruent, and OA=○D' Here, the point ○ is the center of the bending angle 2θ. Also, AD=
DB=DB ' Right triangle AD○ and right triangle B'D○ are congruent,
OA=○B' ・°・OA20 D'=○B' Therefore, in the design bending displacement state, the respective centers Δ, B' and D of the flange 3.4 and the control ring 2
' is equidistant from the center of the design bending angle 0, and the bellows 1
The central axis of is constrained to the arc defined by the design bending angle,
The bellows 1 is deformed so as to draw an arc.

The amount of movement C of the center of one link pin 11 or 12 in the elongated hole 13 or 14 and the distance 2a between the link pins 11 and 12 can be defined as follows.

If AB=l, then c=1-2a θ a/1an = j! / t a nθ θ ,', c=j! tan” θ2 (θ×1) 2a=1−c θ2′=, l1(1−−′)(θ×1) The movement amount C of the center of link pins 11 and 12 is lengthened so as to satisfy the above formula. By providing the holes 13 and 14 in the hinge arms 6 and 7, respectively, it is possible to prevent the displacement from exceeding that allowed by the elongated holes 13 and 14.

In addition, in the above explanation, one bellows and a control ring provided in the center were used, but instead of the control ring, an intermediate flange was used, and a bellows with the same specifications was fixed on both sides of the intermediate flange. It goes without saying that bellows can be used.

Furthermore, although this bellows joint has a pair of intermediate link structures on a pair of hinge structures, it is of course possible to use a single link structure on a pair of hinge structures as long as sufficient buckling strength is obtained. .

〔Effect of the invention〕

As described above, according to the present invention, since movement can be restricted at the center of the bellows, buckling can be evaluated using half the number of ridges. Since the strength against buckling is inversely proportional to the square of the number of threads, it has four times the strength of a conventional hinge-type bellows joint.

Therefore, a large absorption displacement angle can be obtained by increasing the number of peaks without reducing buckling, and the center of the bellows is restrained on the arc at the bending angle θ/2 by the intermediate link structure. , irregular deformation of the bellows is suppressed.

In addition, the longer the bellows has a large number of threads, the more stress it will experience due to its own weight, earthquakes, etc. However, with this bellows joint, the stress that occurs in the bellows is only half the length of a conventional hinge-type bellows joint. . Therefore, the stress due to its own weight and earthquake can be reduced to 1/2 to 1/4 of that of a conventional hinge-type bellows joint with the same number of threads.

Further, even if there is a possibility that the bellows resonates at a low frequency, this problem can be avoided because the movement of the center of the bellows is restrained by the intermediate link structure.

Further, since the intermediate link structure restricts the movement of the hinge structure on the bending corner allowed by the elongated hole, it also serves as an excessive deformation prevention mechanism, so there is no need to newly provide an excessive deformation prevention mechanism such as a stopper.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of a double link hinge type bellows joint according to the present invention, and FIG. 1A is a side view and FIG.
B) is a plan view, (C) is an enlarged view of the elongated hole, FIG. 2 is a diagram for explaining the deformed state of this bellows joint, and FIG. 3 is a diagram showing a conventional example of a hinged bellows joint. FIG. 4 is a diagram showing a bellows column squirm. 1... Bellows, 2... Control ring, 3.
4...Flange, 5...Hinge structure, 6.7...
Hinge arm, 8... Hinge pin, 9... Intermediate link structure, 10... Link arm, 11.12., Link pin,
13.14... Long hole, 21.27... Bellows, 2
2.23.28.29...flange, 24...hinge pin, 25.26...hinge arm.

Claims (2)

[Claims] (1) In a hinge-type bellows joint in which both ends of the bellows are each fixed by at least one set of hinge arms, and each hinge arm is connected at the center by a hinge pin to absorb bending displacement in a predetermined direction, the bellows center a support means for supporting the bellows over its circumference; and pins at both ends that are fixed to the support means at the center and movable along the longitudinal direction of the bellows by fitting into elongated holes provided in each hinge arm. A double link hinge type bellows joint characterized by having an intermediate link mechanism. (2) The support means that supports the center part of the bellows over the circumference is composed of an intermediate flange, and the bellows has two
2. The double link hinge type bellows joint according to claim 1, wherein the double link hinge type bellows joint comprises: