GB2451095A

GB2451095A - Tube coupling device

Info

Publication number: GB2451095A
Application number: GB0713866A
Authority: GB
Inventors: Yuan Yan Wei; Clive Coote
Original assignee: Vertical Leisure Ltd
Current assignee: Vertical Leisure Ltd
Priority date: 2007-07-17
Filing date: 2007-07-17
Publication date: 2009-01-21
Anticipated expiration: 2027-07-17
Also published as: GB0713866D0; GB2451095B

Abstract

A coupling device 1 for releasably coupling first and second axially aligned hollow tubes 10 and 11 end to end. The coupling device comprises a substantially cylindrical body 2 that is adapted to be received within the adjacent ends of the first and second tubes 10 and 11, wherein the device includes adjustment means 3 operable for radially expanding and contracting the cylindrical body 2. In an expanded state of the cylindrical body 2, the coupling device forms a friction joint with each of the tubes, locking the tubes relative to each other. The cylindrical body 2 includes one or two longitudinal slots 4 to allow expansion and contraction of the cylindrical body. The coupling device is particularly used for the joining of pole sections of dance exercise poles.

Description

Couolin2 Device This invention relates to a coupling device. In particular, it relates to a coupling device for dance exercise poles.

Poles for use in dance exercise have become very popular in recent years. Such poles extend between floor and ceiling and generally comprise at least two hollow tubes connected together in series according to the height required. The poles may be erected and dismantled by coupling or decoupling the hollow tubes. To facilitate coupling and decoupling, joints are provided between the tubes. There are presently two forms of joint used, screw joints and insert joints, both of which suffer from drawbacks.

Screw joints are expensive to manufacture, since they require an insert to be welded into the end of a tube and a finishing operation. During use, when a pole becomes warm, the tubes and joint can expand so that the screw threads become locked together and it is difficult to unscrew the joint after use of the pole. Alternatively, the screw joint can be unscrewed during use by anti-clockwise rotation if it is not sufficiently tight.

Insert joints must be smaller than the tubes into which they are inserted, accordingly they are prone to movement within the tubes, which results in flexing of the pole and/or relative rotation of the tubes during use. Furthermore, when a pole becomes warm during use the insert can expand causing the tubes to become locked together and difficult to separate.

The present invention sets out to provide an improved joint, which prevents relative rotation of the tubes, which reduces flexing between the tubes, which can be undone, to allow decoupling of the tubes, when hot, and which is cost effective to produce. -,)-

Accordingly, the present invention provides a coupling device for releasably coupling first and second axially aligned hollow tubes end to end, the coupling device comprising a substantially cylindrical body that is adapted to be received within the adjacent ends of the first and second tubes, wherein the device includes adjustment means operable for radially expanding and contracting it, and in an expanded state, the coupling device forms a friction joint with each of the tubes, locking the tubes relative to each other.

Embodiments of the present invention are described below with reference to the accompanying drawings, in which: Figure 1 is a vertical cross-section of the coupling element, according to a first embodiment, in use; Figure 2 is a horizontal cross-section of the coupling element through line A-A of Figure 1; and Figure 3 is a vertical cross-section of the coupling element, according to a second embodiment, in use.

A coupling device 1 shown in Figures 1 and 2 comprises a body 2, which is a hollow cylindrical tube, and two adjustment means 3, which are operable to radially expand and contract the coupling device 1. In an expanded state the coupling device 1 forms a friction joint with tubes 10, 11 locking them relative to each other, preventing radial or axial movement.

The cylindrical body 2 is provided with two axially extending slots 4, one extending from each end of the body 2. The slots 4 allow the effective diameter of the cylindrical body 2 to be increased or decreased by the adjustment means 3, which increase or decrease the width of the slots 4 by the application of expansive or compressive forces on circumferentially opposed points of the cylindrical body 2.

Whilst in the present embodiment a pair of slots is provided, there may be only a single slot provided that extends along the entire length of the cylindrical body 2.

Each of the adjustment means 3 comprises first and second circumferentially opposed internally threaded elements 5 and a screw member 7. The threaded elements are each fixed to the inner face of the cylindrical body 2 by two countersunk screws 6. An outer surface of each threaded element 5 conforms substantially to the inner face of the cylindrical body, as shown in Figure 2. The first and second threaded elements have axially aligned opposite threads that receive the screw member 7. The screw member 7 has a single external thread and lies entirely within the profile of the cylindrical body 2. Access to the head of the screw member 7, through the outer surface of the cylindrical body 2, is provided by a through hole 8, which allows a user to turn the screw member 7 using a hand tool such as a screwdriver, Allen/Hexagon driver or similar. Since the first and second threaded elements 5 have opposite threads, rotation of the screw member 7 in one direction will pull the first and second threaded elements 5 towards one another, closing the slot 4, and rotation of the screw member 7 in the other direction will push the first and second threaded elements 7 apart, opening the slot 4. The longitudinal axis of the screw member 7 is orthogonal to the slot 4, as clearly shown in Figure 2.

The two adjustment means 3 are provided one adjacent each end of the cylindrical body 2. By virtue of this arrangement, rotation of the upper (first) screw member 7 opens and closes the first slot at the first end and rotation of the lower (second) screw member 7 opens and closes the second slot at the second end. This is advantageous since only one adjustment means need be operated to decouple the hollow tubes 10, 11 and the coupling element 1 may be retained in the hollow tube adjacent the other adjustment means ready for the next time the tubes 10, 11 are to be coupled.

Whilst in the present embodiment two adjustment means are provided, there may alternatively be a single adjustment means 3 only or more than two adjustment means. For example, in the case where a single slot 4 is provided that extends along the entire length of the cylindrical body 2 there may be a single adjustment means 3 provided in a longitudinally central region of the cylindrical body 2. In a further simplified arrangement, the or each adjustment means 3 may comprise a single internally threaded element 5, which is fixed to the inner face of the cylindrical body 2, and a screw member 7. In this case the screw member 7 will contact the inner face of the cylindrical body 2, such that turning the screw in one direction will open the slot 4, by extension of the screw member 7 against the inner face of the cylindrical body 2, and turning the screw in the other direction will close the slot 4, by retraction of the screw member and reduction of the pushing force on the inner face of the cylindrical body 2. In any of the described enthodiments the adjustment means need not be fixed to the inner face of the cylindrical body 2 by screws, it may be fixed by welding or similar.

The cylindrical body 2 is provided on its outer surface, in a longitudinal central region, with a radially extending location pin 9. The pin 9 extends from within the cylindrical body 2 through a hole provided in the outer surface of the cylindrical body 2. The pin 9 extends beyond the outer surface of the cylindrical body 2 by a distance that is substantially equal to the wall thickness of each of the first and second hollow tubes 10, 11, so that it lies flush with the outer surface of each of the tubes 10, 11, as shown in Figure 1. The pin is cylindrical. Each of the first and second tubes is provided with a notch in its end face that is adapted to engage the pin 9. The notch in each tube is semi-circular and engages half of the circumference of the pin 9. The end faces of the tubes 10, Il abut each other, and the outer surfaces of the tubes 10, 11 lie flush, so that the pole is provided with a substantially continuous smooth outer surface.

The tubes 10, 11 are further provided with holes 13 that provide access to the screw members 7, through holes 8, for opening and closing the slot 4. The pin is operable to prevent the coupling element from sliding down within either of the tubes 10, 11 when it is inserted into the tubes 10, 11 and ensures alignment of the holes 8 and the holes 13, so that the screw members 7 may be accessed when the coupling device 1 is located within the tubes 10, 11 as shown in Figure 1.

The operation of the coupling device 1 according to the present embodiment will now be described.

In order to couple together two tubes 10, 11, which form at least part of a dance exercise pole, the coupling device 1, in a contracted state, is inserted into the end of the first tube 10 and the location pin 9 is located within the notch of the first tube 10. With a tool, the screw menther 7 of the first adjustment means 3 is rotated to open the first slot, increasing the effective diameter of the cylindrical body 2 at the first end and forming a friction joint with the first tube 10. Next, the portion of the coupling device 1 that is exposed from the end of the first tube 10 is inserted into the end of the second tube 11 and the location pin 9 is located within the notch of the second tube 11 with the ends of the first and second tubes 10, 11 brought into abutment. Finally, the screw member 7 of the second adjustment means 3 is rotated to open the second slot 4, increasing the effective diameter of the cylindrical body 2 at the first end and forming a friction joint with the second tube 11. The tubes 10, 11 are locked together and relative axial or rotational movement is not possible.

Since the coupling device 1 is insertable into the ends of the tubes 10, 11 in a contracted state it is easy to insert, yet once inserted and expanded it provides a strong friction joint that prevents relative rotational and axial movement of the tubes 10, 11.

In order to de-couple the first and second tubes 10, 11 the screw member 7 of the second adjustment means 3 is rotated to close the second slot 4, reducing the effective diameter of the cylindrical body 2 at the second end, releasing the friction joint with the second tube 11 and allowing for removal of the coupling device 1 from the end of the second tube 11, thereby allowing for decoupling of the tubes 10, 11.

The coupling device 1 remains within the end of the first tube 10 for the next time the tubes are to be coupled. Alternatively, the coupling device may be left in the second tube 11 and removed from the end of the first tube 10. Both screw members 7 can be operated for removal of the coupling device 1 from the ends of both tubes 10, 11.

Since the coupling device 1 is contracted prior to removal, even if it has heated up and expanded during use it is easy to remove.

Figure 3 shows a second embodiment of the invention. The second embodiment is substantially the same as the above described first embodiment, the only difference being the arrangement of the radially extending location pm 109 and the associated notches provided in the end faces of the tubes 110, 111. Accordingly, only the different features are discussed below. It should be noted that the arrangement of the pin 109 and notches described below may replace the arrangement of the pin 9 and notches in the first embodiment.

In contrast to the first embodiment, the pin 109 does not extend beyond the inner surface of the cylindrical body 102, and extends beyond the outer surface of the cylindrical body 102 by a distance that is less than the wall thickness of each of the first and second hollow tubes 110, 111. Each of the first and second hollow tubes 110, 111 is provided with a notch in its end face that is adapted to engage the pin 109. The notches are provided on the inner surfaces of the tubes 110, 111 and do not extend through the walls of the tubes 110, 111, they extend from the inner surfaces of the tubes 110, 111 by a distance that is substantially equal to the distance that the pin 109 protrudes from the outer surface of the cylindrical body 102. The notch in each tube is semi-circular and engages half of the circumference of the pin 109. The end faces of the tubes 110, 111 abut each other, and the outer surfaces of the tubes 110, 111 lie flush, so that the pole is provided with a substantially continuous smooth outer surface.

Since, in this embodiment the hollow tubes 110, 111 are not provided with notches that extend through their walls, but rather with internal notches, each tube is provided with a continuous outer surface.

The operation of the coupling device of the second embodiment is identical to the operation of the first embodiment of the invention.

The arrangement of the pin 9, 109 and notches is not limited to a pin, it may comprise a woodruff key or similar.

Claims

Claims 1. A coupling device for releasably coupling first and second axially aligned hollow tubes end to end, the coupling device comprising a substantially cylindrical body that is adapted to be received within the adjacent ends of the first and second tubes, wherein the device includes adjustment means operable for radially expanding and contracting it, and in an expanded state, the coupling device forms a friction joint with each of the tubes, locking the tubes relative to each other.
2. A device as claimed in Claim 1, wherein the cylindrical body is provided with at least one axially extending slot in its periphery and the adjustment means is operable to open and close the slot, thereby radially expanding and contracting the cylindrical body.
3. A device as claimed in Claim 2, wherein the adjustment means comprises at least one internally threaded element fixed to an inner face of the cylindrical body and at least one screw member that is received by the threaded element.
4. A device as claimed in Claim 2 or 3, wherein the adjustment means comprises circumferentially opposed first and second internally threaded elements fixed to an inner face of the cylindrical body and a screw member received therein, wherein the first and second threaded elements have axially aligned opposite threads that receive the screw member; whereby rotation of the screw member in one direction pulls the first and second threaded elements towards one another, closing the slot, and rotation of the screw member in the other direction pushes the first and second threaded elements apart, opening the sloL
5. A device as claimed in any of Claims 2 to 4, wherein there is a single slot provided which extends along the entire length of the cylindrical body.
6. A device as claimed in any of Claims 2 to 4, wherein two slots are provided, one extending from each end of the cylindrical body.
7. A device as claimed in any of Claims 4 to 6, wherein two adjustment means are provided, one adjacent each end of the device, such that rotation of the screw member of the first adjustment means opens and closes the slot at the first end and rotation of the screw member of the second adjustment nieans opens and closes the slot at the second end.
8. A device as claimed in any of Claims 3 to 7, wherein the outer surface of cylindrical body is provided with at least one through hole, so that the screw member may be accessed with a tool for turning the screw member.
9. A device as claimed in any preceding claim in combination with first and second tubes, wherein the cylindrical body is provided on its outer surface, in a longitudinal central region, with a radially extending location pin and the first and second hollow tubes are provided in their end faces with notches that are adapted to engage the pin.
10. The combination as claimed in Claim 9, wherein the first and second hollow tubes are provided with holes that, in use. are aligned with the screw members provided for opening and closing the slot.
11. A coupling device substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawings.