WO2000019136A1

WO2000019136A1 - A device for connecting two bodies

Info

Publication number: WO2000019136A1
Application number: PCT/NO1999/000297
Authority: WO
Inventors: Knut Bekkevold
Original assignee: Kongsberg Offshore As
Priority date: 1998-09-30
Filing date: 1999-09-29
Publication date: 2000-04-06
Also published as: NO984569D0; NO309666B1; NO984569L; AU6011599A

Abstract

A device for connecting a first (2) and a second (6) pipe, comprising an eye nut (28) which is arranged to extend round the first pipe (2). Near one end (32) the eye nut (28) has internal threads (34) for screwing on to external threads (26) of the second pipe (6) and near its other end a contact face (36) which projects towards the eye nut's (28) longitudinal axis, which is arranged for cooperation with a complementarily formed contact face (24) of the first pipe (2), thus enabling the pipes to be pulled together until surfaces, such as end surfaces (10, 12) of the pipes come into contact with each other. According to the invention the first contact face (24) also extends towards the end surface (10) of the first pipe (2) and the eye nut's (28) contact face also extends away from the end (32) which is located at its threaded portion.

Description

PATENT CLAIMS

1. A device for connecting two bodies, especially a first (4) and a second (8) mutually coaxially extending end portion of a first (2) and a second (6) pipe respectively, wherein - the first end portion (4) has a free end ( 10) and a first contact face (24), which extends away from the longitudinal axis of this end portion (4) at a distance from the end ( 10) and faces away from this end ( 10),

- the second end portion (8) has external threads (26), and

- the pipe coupling comprises an eye nut (28) which is arranged to extend round the first end portion (4), the eye nut (28) having a third end portion

(30) with a free end (32) and internal threads (34) for screwing on to the second end portion's (8) external threads (26), and a second contact face (36). which is complementary relative to the first contact face (24). and which extends towards the eye nut's (28) longitudinal axis and faces the end (32) of the third end portion (30), characterized in that the first contact face (24) also extends towards the first end portion ( 10), and the second contact face (36) also extends away from the third end portion (30).

2. A device according to claim 1 , characterized in that the first contact face (24) is a surface of at least one pressure body (50) which extends along at least a part of the periphery of the first pipe end portion (4). and which is attached to this pipe end portion (4), for transfer of an axial force which is exerted against the first contact face (24) of the first pipe (2).

3. A device according to claim 2, characterized in that an engagement portion (52) of the pressure body (50) engages with a radially outwardly open groove (40) of the first end portion which is complementarily formed to this engagement portion (52).

4. A device according to claim 3, characterized in that the area (74, 76) of the groove (40) which is located nearest the end ( 10) of the first end portion is undercut.

5. A device according to claim 4, characterized in that the portion of the undercut area (74, 76) which is located near the groove's (40) opening is circular, viewed in a cross section through the groove (40).

6. A device according to one of the claims 2-5, characterized in that in the pressure body (50) there is provided at least one first bore (60), which, when the pressure body is mounted in the groove (40) of the first end portion (4), extends axially, and in the second end portion (8) there is provided at least one second bore (64) corresponding to the first bore (60), and that the device comprises a guide pin (72) which is slidable relative to at least one of the bores (60, 64) for simultaneous insertion in the first and the second bore (60, 64) during a connection of the pipes (2, 6).

7. A device according to one of the claims 2-6, characterized in that the pressure body (50) is attached to the first pipe (2) by means of at least one radially extending screw (68) which extends with clearance through an associated, radially extending hole (56, 58) of the pressure body (50).

8. A device according to one of the preceding claims, characterized in that the angle (α) which is formed by the eye nut's (28) longitudinal axis and the second contact face (36), viewed in a longitudinal section through the eye nut, is about 7°.

A device for connecting two bodies

The invention relates to a device for connecting two bodies, especially a first and a second mutually coaxially extending end portion of a first and a second pipe respectively, wherein - the first end portion has a free end and a first contact face, which extends away from the longitudinal axis of this end portion at a distance from the end and faces away from this end,

- the second end portion has external threads, and

- the pipe coupling comprises an eye nut which is arranged to extend round the first end portion, the eye nut having a third end portion with a free end and internal threads for screwing on to the second end portion's external threads, and a second contact face, which is complementary relative to the first contact face, and which extends towards the eye nut's longitudinal axis and faces the end of the third end portion. From NO 157950 there is known a screw system with components which resemble the components of the above-mentioned device, where the contact faces extend radially, with the result that the line of effect for the force, which is exerted between the contact faces when the eye nut is screwed on to the threaded portion of the second pipe and tightened, extends axially. Since this force and the associated reaction force, which is exerted between the threaded portions of the eye nut and the second pipe, are exerted near the radially internal lateral portion of the eye nut, these forces also attempt to extend the nut axially via this lateral portion, as well as bending the eye nut in such a manner that the eye nut's central portion is narrowed, i.e. the eye nut's end portions become widened in a trumpet shape towards the ends of the eye nut. In the radially internal portion of the eye nut, therefore, substantially axial tensile stresses are exerted, while in the radially external portion of the eye nut axial tensile stresses are exerted. In order for the eye nut to withstand these complex stresses, it must have correspondingly large dimensions.

The object of the invention is to provide a device of the type mentioned in the introduction, which is encumbered to a lesser extent with the above- mentioned disadvantages. The characteristics of the device according to the invention are set forth in the characterizing clause of the claims.

The invention will now be described in more detail with reference to the drawing which schematically illustrates embodiments of the device according to the invention, where it is used as a pipe coupling for interconnection of two pipes.

Fig. 1 illustrates a longitudinal section through a first embodiment of a pipe coupling according to the invention.

Fig. 2 illustrates a longitudinal section through a second embodiment of a pipe coupling according to the invention.

Fig. 3 illustrates an enlarged section of the portion which is indicated by II in fig. 2.

Fig. 4 is a perspective view of the pipe coupling illustrated in fig. 2, where components of the coupling have been separated from one another.

As can be seen in fig. 1 , the pipe coupling comprises a first pipe 2 with a first shoulder or end portion 4 and a second pipe 6 with a second shoulder or end portion 8. The first end portion 4 has a first end surface or end 10, and the second end portion 8 has a second end surface or end 12. which during a movement of the pipes 2, 6 towards each other when they extend coaxially, are arranged to come into contact with each other. Between adjacent, e.g. cylindrical surface portions 14, 16 of the pipes 2 and 6 respectively, there may be provided suitable sealing means, such as an O-ring 18, thus enabling the pipes to communicate sealingly with each other.

At a distance from the first shoulder surface 10 the first end portion 4 has a first contact face 24, which extends away from this end portion's longitudinal axis and simultaneously towards the first shoulder surface 10, the contact face 24 facing away from this shoulder surface 10.

The second end portion 8 is provided with external threads 26.

Round the first end portion 4 of the first pipe 2 there is arranged an eye nut 28 which has a third end portion 30. This end portion 30 has a free end surface or end 32 and internal threads 34 for screwing on to the second end portion's external threads 26. Furthermore, this end portion 30 has a second contact face 36, which is complementary relative to the first contact face 24, and which extends towards the eye nut's longitudinal axis and faces the end 32 of the third end portion.

When the eye nut 28 has been screwed on to the second end portion 8 of the second pipe 6 and tightened, the first and the second contact face 24 and 36 respectively come into contact with each other. Due to the fact that the contact faces extend slantingly relative to a radial line, the force which is exerted against the eye nut's contact face 36 is not directed axially, but substantially perpendicularly thereto, i.e. simultaneously away from the eye nut's longitudinal axis and away from the end 32 of the eye nut's end portion 30. There is thereby exerted at the location of the contact face 36 of the eye nut 28 a radially outwardly directed component of the force which attempts to bend the eye nut, thus causing it to assume a barrel shape, i.e. its central portion has a greater diameter than its ends. The stresses in the eye nut are thereby reduced, thus enabling the eye nut to have smaller dimensions and be lighter.

The pipe coupling according to this embodiment is naturally encumbered with the drawback that the eye nut, e.g., must be threaded on to the first pipe 2 from its other end due to the widened portion of the pipe 2 which comprises the contact face 24. In order to avoid this drawback, the pipe coupling may be made as illustrated in figs. 2-4.

The components of the second embodiment which correspond to components of the first embodiment according to fig. 1 are given the same reference numerals in figs. 2-4.

As illustrated in figs. 2-4, in the first end portion 4 there is provided a radially outwardly open, circumferential groove 40 which is substantially U- shaped in cross section.

Into the groove 40 there projects an engagement portion 52 of at least one pressure body 50 in the form of a circular arc or a segment of a circle, which body extends at least along a portion of the length of the groove. Several pressure bodies are preferably arranged successively along the length of the groove. The portion of the pressure body 50 which projects out of the groove 40 has on one side an axial extension 54 which extends axially to the location of the first shoulder or end surface 10 of the first end portion 4. The other side of the portion of the pressure body which projects out of the groove 40 has a surface 24' which is formed in the same way as the first contact face 24 and is arranged for abutment with the second contact surface 36 of the eye nut 28.

In the pressure body's extension 54 there is provided at least one radially extending bore 56 with a recessed portion 58. Moreover, in the extension 54 there may be provided at least one axial bore 60, which leads into the shoulder surface 10.

In the first end portion 4 there is provided at least one radial bore 62 which is aligned with the radial bore 56, 58 in the extension 54, and which is provided with threads. In the second end portion 8 there may be provided at least one bore 64 which extends coaxially with the bore 60 in the extension 54. For connection of the pressure body 50 with the first end portion 4 there is inserted in the bore 56 a screw 68 which is screwed into the threads of the bore 62, and whose head 70 can come into abutment against the bottom of the recessed portion 58. A clearance is hereby provided between the screw's stem and the bore 56, thus enabling the pressure body 50 to be moved slightly in an axial direction relative to the screw 68. In the bores 60. 64 there is inserted a guide pin 72 which can slide with only a small clearance in the bores 60 and 64 of the extension 54 and the second end portion 8 respectively.

There are preferably provided so many pressure bodies that they extend with only a small clearance from one another along the groove 40. Before the pressure bodies 50 are mounted on the first end portion 4, the eye nut 28 can thus be threaded on to this end portion, whereupon the pressure bodies are attached to the end portion.

The angle which is formed by a radial line and the first contact face 24, viewed in a longitudinal section, is preferably about 7°.

The side 74 of the groove 40 which is located near the first end 10, i.e. the side of the groove which comes into abutment against the pressure body 50 when the eye nut 28 is tightened, is concave in form, preferably circular, with the result that this side 74 of the groove is undercut viewed radially inwards into the groove. This side 74 therefore has a nose 76 which projects away from the shoulder surface 10. The adjacent side 78 of the pressure body 40 is formed in a complementary manner to the side 74, thereby providing a secure hold for the pressure body 28 in the groove 40.

During connecting of the pipes and tightening of the eye nut 28 the pressure body may be moved slightly relative to the first end portion 4 due to the clearance between the screw 68 and the bore 66, 68, while the guide pin 64 guides the pressure body axially, whereupon the pressure body comes into surface abutment against the side of the groove 74.

For screwing the eye nut by means of a tool such as a spanner, the eye nut may have a circumferential portion 88 in the form of a portion of a hexagon nut. or it may be crenulated or the like. Furthermore, it will be understood that in connection with the components according to the invention there may be provided in a known per se manner concave rounded corners which give a reduction in stress concentrations.

Even though the invention has been described in the above in relation to the connection of two pipes, it will be understood that it may be employed in any case where an internal collar of an eye nut abuts against a circumferential flange of a first object, which has been threaded into the eye nut. and where the eye nut is screwed on to another object in order thereby to pull the objects towards each other with great force.