WO1992006322A1

WO1992006322A1 - Rotational connectors

Info

Publication number: WO1992006322A1
Application number: PCT/GB1991/001695
Authority: WO
Inventors: Anthony John Asbury
Original assignee: Anthony John Asbury
Priority date: 1990-10-02
Filing date: 1991-10-02
Publication date: 1992-04-16
Also published as: AU8625791A; GB9021385D0; EP0551340A1

Abstract

A connector for joining together two members has male and female portions (1, 2) which may be interfitted together, the connection then being made by partial rotation of one portion with respect to the other. One portion has arcuately spaced radial projections (13) the peripherial profile of each of which is generally arcuate whereby the radial extent of the projection increases progressively from a minimum at the leading end thereof, having regard to the direction of turning to make the connection. The other portion has arcuately spaced slots (19) each able to receive a projection of the one portion, with recesses defined between the slots (19) to receive the projections (13) on initial fitting together of the two portions. The walls of the projections and slots which interengage are inclined to a true radial plane whereby making of the connection also moves one portion axially with respect to the other. Abutment faces (11 and 12) may also be provided on the two portions (1, 2), which faces engage on initial fitting together of the two portions, the connector then being subjected to a preload on final making of the connection.

Description

ROTATIONAL CONNECTORS

The present invention relates to a connector for connecting together two members, and in particular, but not exclusively, to a tubular connector for connecting together tubular members such as are used in the oil and gas industries.

The oil and gas industries utilise various means for connecting together tubular members, such as conduits and/or struts. Several important criteria need to be considered when designing or selecting a suitable connector for a given such purpose: the role of the connector; the required level of integrity of the connection; the nature of any fluids to be carried thereby; and the general mechanical "environment" of the connected assembly. A vital aspect to be considered, particularly with respect to offshore applications, is the anticipated fatigue spectra to which the assembly will be exposed. The connected assembly must either be inherently sufficiently robust to resist fatigue loads or, preferably, employ such a connector system that the impact of fatigue loadings becomes controlled and much reduced. One such latter approach involves introducing a pre-load element into the assembled joint whereby relative movement of the connector interfacing components is restricted for loads up to the maximum anticipated load.

Particularly in the oil and gas industries, where a multiplicity of connections may need to be made up in rapid succession, convenience of assembly of the connection may be critical. Making of the connection should be quick and involve the minimum of specialist equipment.

When designing a tubular connector, the practicality of manufacturing the connector components must be taken into consideration. They must be capable of being manufactured in a manner which both permits the use of currently available machine tool technology and facilitates the economical production of small and large quantities of the components . Useful attributes to be aimed at include simplicity of design, minimisation of the number of components of the connector, provision of components with uncomplicated, smoothly-blending profiles and maximisation of tolerances.

The connector should also be readily disconnectable, to facilitate separation of the tubing assembly.

The multiplicity of known tubular connectors satisfy various of the above design criteria in varying degrees. Particularly, where a pre-load element is to be provided in the assembled joint, many known connectors are extremely complex. Examples of such connectors include those which are made up by high pressure hydraulic interfacing means. Such connectors may also have tight constraints on thread transverse- sectional profiles. Other types of pre-loaded connection make use of helical or part helical threads . Such threads often induce substantial delays during make-up of the connections and have a number of other drawbacks including, in some cases, narrow tolerance ranges .

It is a general object of the present invention to satisfy the above design criteria, and to reduce the aforementioned drawbacks of the prior art.

According to one aspect of the present invention, there is provided a connector for connecting together two members, which connector comprises a male and female portions associated, in use, with the two members respectively, one of said portions having at least one part-circumferentially-extending key means, and the other of said portions having at least one part-circumferentially-extending slot means co-operable with the key means of the one portion, there being a like number of longitudinally-extending recesses as there are key means which recesses are defined in said other portion to accommodate the key means of the one portion when the two portions are fitted together prior to interlocking of said key means and slot means, said key means and slot means being interlocked, in use, by partial relative rotation of the two portions to interengage said key means and slot means, the key means and the slot means both being defined by transverse walls of the respective portions and the transverse wall of at least one of the portions which wall is engaged by the corresponding wall of the other portion being inclined to a true radial plane whereby the male and female portions are progressively cammed axially together as said key means and slot means radially interlock progressively more deeply. The radial extent of the or each key means preferably increases progressively from a minimum at the end thereof which first enters the slot means on interengaging the two connector portions. Each said key means may thus have an arcuate peripheral profile, and so be of a "lobar" profile. The length of such key means may lie wholly in a radial plane, unlike the case where a helical thread is employed.

Advantageously, the transverse walls of both portions and which engage one another to effect interlocking are both inclined at substantially the same angle to a true radial plane. The other transverse walls may also be similarly inclined, or may lie in radial planes.

There may be two, but preferably three, circumferentially-spaced, arcuately-extending key means, and a like number of circumferentially-spaced, arcuately-extending slot means with said recesses being defined between said slot means . In addition, the or each key means may include a plurality of axially- spaced, circumf erentially-aligned like key elements , and each slot means then including a like plurality of axially-spaced, circumf erentially-aligned like slot elements interengageable by the key elements .

Pref erably , the two connector portions are provided with re spective abutment f ac e s which interengage on fitting together the two portions , the interengaging pressure being increased by the axial camming action occurring on interlocking the connector portions . In this way, the connector may be given a pre-load. Both abutment surfaces may extend generally radially, or may be of conical form^*.

According to a second aspect of this invention, there is provided a connector for connecting together two members , which connector comprises male and female portions associated , in use , with the two members respectively, one of said portions having at least one part-circumf erentially-extending key means , and the other of said portions having at least one part- circumferentially-extending slot means co-operable with the key means of the one portion, there being a like number of longitudinally-extending recesses as there are key means which recesses are defined in said other portion to accommodate the key means of the one portion when the two portions are fitted together prior to interlocking of said key means and slot means , said key means and slot means being interlocked , in use , by partial relative rotation of the two portions to interengage said key means and slot means , the or each key means being in the form of a rib projecting in the radial direction from said one portion and having a curved peripheral profile, the radial projection of the rib increasing from a minimum at the end thereof which first enters the slot means on interengaging the two connector portions .

The or each key means may have an arcuate peripheral profile of a smaller radius of curvature than that of the surface from which the key means upstands; the key means may thus have a "lobar" profile, and the slot means should be similarly formed. By way of example only, certain specific embodiments of this invention will now be described in detail, reference being made to the accompanying drawings, in which:-

Figure 1 is a transverse-sectional view of part of a connector embodying the invention, illustrating the inter-fitted but unlocked state of the male and female portions of the connector;

Figure 2 is a longitudinal sectional view of the connector of Figure 1 taken along the line II-II on

Figure 1;

Figure 3 is a transverse-sectional view of the connector of Figure 1 illustrating the male and female portions of the connector in the interlocked state;

Figure 4 is a longitudinal section view of the connector of Figure 1 taken along the line IV-IV on

Figure 3; Figures 5 to 7 are partial longitudinal sectional views of the connector of Figure 1 and illustrating successive stages in the transition from the unlocked state to the interlocked state;

Figures 8 to 10 are transverse-sectional views of the connector, illustrating successive stages in the transition from the unlocked state to the interlocked state;

Figure 11 is a transverse-sectional view of the connector of Figure 1 and illustrates the provision of a secondary locking pin;

Figure 12 is a longitudinal sectional view taken along the line XII-XII on Figure 11;

Figures 13 to 15 are transverse-sectional views of an alternative embodiment of connector incorporating a circlip, and illustrating the insertion of the circlip (Figure 13 and Figure 14) and the interlocked state of the connector (Figure 15);

Figures 16 to 18 are longitudinal sectional views taken along the lines XVI-XVI, XVII-XVII and XVIII-XVIII of Figures 13 to 15, respectively; Figure 19 is a transverse-sectional view of a further embodiment of the invention in the interfitted and unlocked states, the male connector portion having an eccentric circular external spline; and Figure 20 is a longitudinal sectional view of the connector of Figure 19 taken along the line XX-XX.

Referring to Figures 1 and 2, the tubular connector comprises a male tubular portion 1 and a female tubular portion 2. The end of the male portion 1 illustrated in Figure 2 essentially comprises four stepped circumferential outer surfaces 3, 4, 5 and 6 of progressively smaller diameter. The latter three outer surfaces 4, 5, and 6 are designed to fit within correspondingly stepped inner circumferential surfaces 7, 8 and 9 in an end of the female portion 2, such that the end surface 11 of the male portion abuts a shoulder 12 formed at the transition between the stepped inner surface 9 and the innermost bore 10 of the female portion 2. A distinctive feature of the third stepped outer surface 5 of the male portion 1 is the provision of three equally spaced circumferentially extending radially projecting lobes 13, 14 and 15. These lobes 13, 14 and 15 each comprise three axially spaced circumferentially extending lobar external splines (keys) 13A to 13C, 14A to 14C, 15A to 15C. Arcuate recesses 16, 17 and 18 are provided in the intermediate stepped internal surface 8 of the female portion 2 and extend longitudinally of that portion to accommodate the lobes 13, 14 and 15 of the male portion 1 when the male portion 1 is inserted into the female portion 2 prior to locking. Circumferentially extending internal slots 19A to 19C are formed in the internal surface 8 of the female portion 2, and are co-operable with the external splines 13A to 13C, 14A to 14C and 15A to 15C, respectively, when the end surface 11 of the male portion 1 abuts the shoulder 12 of the female portion 2.

Referring to Figures 3 and 4, the connector is shown in the locked state, with the external splines 13A to 13C, 14A to 14C, 15A to 15C of the male portion fully engaged with the internal slots 19A to 19C of the female portion 2. This state is achieved by partial rotation of the male portion 1 in either direction when fully within the female portion 2 and under an axially compressive load (e.g. gravity) using, for example, torque wrench. The splines and slots respectively of the male and female portions progressively inter-engage as the external splines 13A to 13C, 14A to 14C, 15A to 15C move out of alignment with the recesses 16, 17, 18 and into alignment with the slots 19A to 19C. Once fully engaged, further rotational movement of the male portion 1 relative to the female portion 2 is prevented by abutment of the splines 13A to 13C, 14A to 14C, 15A to 15C against respective stop surfaces 20A, 20B and 20C. These stop surfaces 20A to 20C may be so profiled that they enable the splines to travel slightly beyond them before being fully stopped to reduce the possibility of unlocking 'backing off) of connector in response to vibration.

The progressive inter-engagement of the male and female portions 1 and 2 is shown in Figure 5 to 7 and 8 to 10. In Figures 5 and 8 the external splines 14A to 14C are not engaged with the slots 19A to 19C. In Figures 6 and 9, after a small partial rotation of the male portion 1 relative to the female portion 2, the splines 14A to 14C have become partially interengaged with slots 19A to 19C. The substantially lobar shape of the splines dictates that the engagement is progressive, and not as abruptly as would occur in the splines were square-ended, in plan. The importance of this will become apparent from the following.

Referring to Figures 7 and 10, as the male portion 1 is further rotated within the female portion 2, the splines 14A to 14C extend deeper into the slots 19A to 19C. As can be seen from the drawings, however, the side walls of the slots 19A to 19C are inclined to the true radial plane and so cam the male portion deeper into the female portion 2. Because the male and female portions 1 and 2 are already in axial abutment, this has the effect of inducing an axial pre-load between the abutting end 11 of the male portion 1 and the shoulder 12 of the female portion 2. In use, the connector can rapidly and easily be coupled. The male and female connector portions 1 and 2 can be integrally formed with, or be fitted by any suitable means including for example welding to, the ends of the tubular members to be joined. The splines of the male portion 1 are aligned with the recesses 16, 17 and 18 of the female portion 2 to enable the male portion 1 to be inserted into the female potion 2 until the end surface 11 of the male portion abuts the shoulder 12 of the female portion. Once fully inserted, the male portion need only be rotated by as little as, for example, ten degrees fully to inter¬ engage the splines 14A to 14C etc. of the male portion 1 with slots 19A to 19C of the female portion, thereby axially locking the portions of the connector together and pre-loading the connection. Secondary locking, to hold the inter-locked splines together may be accomplished (as shown in Figures 11 and 12) by inserting a threaded pin 21 through the wall of the female portion 2 to abut the male portion 1, behind one of its splines. Integrity of the connector for use as a conduit may be enhanced by the provision of sealing means, such as, for example, O-rings, in any suitable manner as will be obvious to anyone skilled in the art.

In comparison to helical threads, the splines of the connector of the present invention may have a far greater variety of transverse-section profiles. The pitch of a helical thread is necessarily kept low to limit make-up torques and the depth and thickness of the thread is similarly limited. The present splines, however, may be of greater pitch, depth and thickness, the former enabling greater mechanical advantage in camming together the male and female portion of the connector, and the latter reducing the risk of shearing under load.

In addition to the above described embodiment of the invention, numerous other embodiments are possible. For example, the key means need not comprise splines. The key means could be defined by a profiled circlip 22, as shown in Figures 13 to 17. Such a circlip or snap-ring may serve initially to hold together the male and female portions following insertion, but before inter-locking thereof. Thereafter, on turning the male portion, a tight pre-loaded connection may be obtained.

The key means of the connector may be provided on the female portion of the connector, and the slot means on the male portion, but this approach is comparatively wasteful of labour and materials. The number of "lor 3" and number of splines per "lobe" is variable. Furthermore, the splines need not be lobar at all. They may for example be of generally triangular or of any other shape which has a leading edge (the edge which first engages with the internal slots) which enables progressively deeper inter-engagement. Lobar spines are preferable because they are simple to form by turning without the need for more complex machining (e.g. milling) and because they have no corners which may become damaged or cause damage in use.

Such "lobar" splines may comprise, for example, the vertices of an ellipsoidal male connecting portion (Figures 8 to 10) or a triangular male connecting portion. Another possibility is for the protrusion to be defined by an eccentric circular male connecting portion, as shown at 23 in Figures 19 and 20.

Various improvements may be made to the connector. For example, the female portion of the connector may comprise a rotatable collar fitted over a stem, the stem being that part of the female connector portion which is associated, in use, with one of the two members to be joined.

The mating ends of the male and female portions may be designed to be frusto-conical in shape to facilitate alignment of the two portions during assembly.

For any of the embodiments described above, it is possible to offect a degree of control over the amount of rotation for connector make-up and introduce rotational stops both to limit make-up rotation and to provide back-stops to limit reverse rotation for disassembly, by offsetting the centre of the turning arc through which the male connector portion is turned to inter-lock or unlock the key means and slot means.

Claims

1. A connector for connecting together two members, which connector comprises male and female portions associated, in use, with the two members respectively, one of said portions having at least one part- circumferentially-extending key means, and the other of said portions having at least one part- circumferentially-extending slot means co-operable with the key means of the one portion, there being a like number of longitudinally-extending recesses as there are key means which recesses are defined in said other portion to accommodate the key means of the one portion when the two portions are fitted together prior to interlocking of said key means and slot means, said key means and slot means being interlocked, in use, by partial relative rotation of the two portions to interengage said key means and slot means, the key means and the slot means both being defined by transverse walls of the respective portions and the transverse wall of at least one of the portions which wall is engaged by the corresponding wall of the other portion being inclined to a true radial plane whereby the male and female portions are progressively cammed axially together as said key means and slot means radially interlock progressively more deeply.

2. A connector as claimed in claim 1, wherein the radial extent of the or each key means increases progressively from a minimum at the end thereof which first enters the slot means on interengaging the two connector portions.

3. A connector as claimed claim 2, wherein each said key means has an arcuate peripheral profile.

4. A connector as claimed in any of the preceding claims, wherein said transverse walls of both portions and which engage one another to effect interlocking are both inclined at substantially the same angle to a true radial plane.

5. A connector as claimed in any of the preceding claims, wherein there are at least two circumferentially-spaced, arcuately-extending key means, and a like number of circumferentially-spaced, arcuately-extending slot means with said recesses being defined between said slot means.

6. A connector as claims in claim 5, wherein there are provided three arcuately spaced key means, and a like number of slot means and of recesses to receive the key means.

7. A connector as claimed in any of the preceding claims, wherein each key means includes a plurality of axially-spaced, circumferentially-aligned like key elements, and each slot means includes a like plurality of axially-spaced, circumferentially-aligned like slot elements interengageable by the key elements.

8. A connector as claimed in any of the preceding claims, wherein each of the peripherally-extending key means and slot means extend substantially in a radial plane.

9. A connector as claimed in any of the preceding claims, wherein the two connector portions are provided with respective abutment faces which interengage on fitting together the two portions, the interengaging pressure being increased by the axial camming action occurring on interlocking the connector portions.

10. A connector as claimed in claim 8, wherein both abutment surfaces extend generally radially.

11. A connector as claimed in any of the preceding claims, wherein the two connector portions are both substantially tubular, for use with tubular members.

12. A connector as claimed in any of the preceding claims, wherein the key means are provided on the male connector portion and the slot means are provided on the female connector portion.

13. A connector for connecting together two members, which connector comprises a male and female portions associated, in use, with the two members respectively, one of said portions having at least one part- circumferentially-extending key means, and the other of said portions having at least one part- circumferentially-extending slot means co-operable with the key means of the one portion, there being a like number of longitudinally-extending recesses as there are key means which recesses are defined in said other portion to accommodate the key means of the one portion when the two portions are fitted together prior to interlocking of said key means and slot means, said key means and slot means being interlocked, in use, by partial relative rotation of the two portions to interengage said key means and slot means, the or each key means being in the form of a rib projecting in the radial direction from said one portion and having a curved peripheral profile, the radial projection of the rib increasing from a minimum at the end thereof which first enters the slot means on interengaging the two connector portions.

14. A connector as claimed in claim 13, wherein the or each key means has an arcuate peripheral profile of a smaller radius of curvature than that of the surface from which the key means upstands.