GB2315105A

GB2315105A - Connecting elongate members together

Info

Publication number: GB2315105A
Application number: GB9713796A
Authority: GB
Inventors: Colin Sidney Smith
Original assignee: Tube Plastics Ltd
Current assignee: Tube Plastics Ltd
Priority date: 1996-07-05
Filing date: 1997-07-01
Publication date: 1998-01-21
Anticipated expiration: 2017-07-01
Also published as: GB9614097D0; HK1011557A1; GB9713796D0; GB2315105B

Abstract

Two circular section tubes (10, 12) (Figure 2) are connected together by the use of an end plug (13) fitted in the end of the tube (12), the plug having a nut (24) therein (or an integral screw-thread) which is engaged by a threaded shank (28) of a headed screw (26), the screw passing diametrically through the tube (10) and through a hole (17) in tube (12), so that when the screw is fully tightened, the head (27) of the screw is engaged against the tube (10) with the two tubes (10,12) engaging against one other. In Figure 3, a double-ended plug 36 joins the tubes 37,38, as well as the tube 30, and the plug 33 joins overlapped tubes 31,32.

Description

METHOD OF CONNECTING ELONGATE MEMBERS AND AN ASSEMBLY OF MEMBERS CONNECTED THEREBY This invention relates to a method of connecting together elongate members, such as tubes, and also to an assembly of such connected members. The invention has particular application to the connection of tubes to form children's outdoor activity apparatus such as climbing frames, swings, slides, iadders etc.

With such apparatus where it is required for two tubes to be bolted together, often at 900 to one another, it is usual to provide circular holes at respective opposite diametrically aligned sides of each tube and to piace the tubes together at their desired relative orientation. A headed bolt is then passed through the aligned four holes until its head engages one of the tubes, with the end of its threaded shank protruding out of the other tube. A nut is then threadedly engaged on this protruding end and screwed up tightly to engage the other of the tubes, thereby completing the nut and bolt connection to hold the tubes together.

This arrangement is unsatisfactory in several respects. Firstly the end of the bolt shank, the nut and the bolt head are all normally of metal, and, if uncovered, represent a part of the apparatus on which a child could catch its clothes or cut itself. Secondly, these visible projecting parts of the connection are unsightly, even with caps, ferrules or the like being arranged to try to cover them up. Moreover, separate additional end caps are required to close the ends of the tubes. Thirdly, since the connection is readily accessible, it is normally relatively easy to tamper with, i.e. loosen, the fixing, with, for example, such vandalism endangering subsequent use of the apparatus incorporating such fixings.

An object of the invention is to reduce at least some of these prior art disadvantages.

According to a first aspect of the invention there is provided a method of connecting together two elongate members, one of which has a transverse or generally transverse bore defined therethrough, and the other of which has a discrete transverse or generally transverse bore extending to an internal tubular part thereof, which is in communication with an open end of said other elongate member, the method comprising engaging in said open end an insert which forms an end plug which extends to said tubular part, within which it provides a screw-thread, arranging the two members so that the bore defined through said one member is aligned with the discrete bore of the other member, passing a headed fixing element through said bore defined through said one member and said discrete bore of the other member so that a screwthread of the fixing element initially engages the screw-thread provided by the insert, and screwing up said fixing element so that part thereof is held in said insert, thereby to connect the two members together.

Preferably the fixing element is screwed up until respective outer side surfaces of the two members engage. Advantageously the head of the fixing element engages against said one member.

According to a second aspect of the invention there is provided an assembly comprising two connected elongate members, one member having a transverse or generally transverse bore defined therethrough, the other member having a discrete transverse or generally transverse bore extending to an internal tubular part thereof, which is normally in communication with an open end of said other elongate member, an insert engaged in said open end to form an end plug which extends to said tubular part, within which it provides a screw thread, and a headed fixing element received through said bore defined through said one member and said discrete bore of the other member, and being screwthreadedly engaged with said insert by means of said screw-thread thereof.

Preferably the insert has a peripheral skirt portion spaced outwardly from the part of the insert received within the end of said other member and engaging the outer side surface of said other member.

Desirably, the screw-thread provided by the insert is that of a nut held against rotation in a cavity of the insert.

Conveniently both members are hollow circular section tubes.

The invention will now be described, by way of example, with reference, to and as shown in the accompanying drawings, in which: Figure 1 is a fragmentary view of a ladder incorporating the present invention, Figure 2 is an enlarged part-sectional view of part of the ladder of Figure 1, showing an assembly of the invention, Figure 3 is a part-sectional diagrammatic view showing the connecting together of various tubes in accordance with the invention, Figure 4 is a schematic fragmentary interior view of part of the assembly of tubes of Figure 3, and Figures 5 and 6 show alternative internal forms of insert of the invention each received in a circular tube.

Although the present invention is applicable to the connecting together of elongate members generally, i.e. with the members being of any various forms, it is particularly applicable to the joining together of hollow tubes, normally of circular cross-section, and specific embodiments hereinafter described will relate to the connecting together of circular-section hollow tubes, generally of steel or of plastics material.

However it will be appreciated that the invention is applicable to elongate members which are other than of circular external section and which may be closed/solid along most of their length, but with an internal recess/tubular portion to receive a fixing insert as will be described in relation to the embodiments mentioned below.

The invention is particularly applicable to childrens outdoor play apparatus, such as climbing frames, swings, slides, ladders, etc. where various lengths of circular-section hollow tubes are connected together in various orientations.

Figure 1 shows the bottom of a ladder comprising a pair of spaced downwardly diverging uprights 10, 11 respectively, connected together by a series of spaced vertical rungs, the lower one of which is denoted by the reference numeral 12. As can be seen from Figure 1, which illustrates the front of the ladder, no fixing means are visible at the front side of the rung, at opposite ends of which are fitted respective end caps in the form of inserts 13, 14.

Figure 2 shows in enlarged interior detail, the nature of the connection between an upright, in this case the upright 10, and the lower rung 12, each of which is formed of hollow circular-section tube. The upright 10 is formed with a pair of diametrically aligned circular holes 15, 16 respectively at its opposite sides, the two aligned holes together defining a transverse through bore. The tube constituting the lower rung 12 has a discrete, i.e. single, circular hole or bore 1 7 in its outer surface, and in use, when the two tubes are to be connected together, the upright 10 is engaged against the outer side surface of the rung 12 as shown in Figure 2, with the holes 16 and 17 aligned.

With the arrangement shown in Figure 2, the hole 1 7 in the lower rung is formed adjacent an open end of the tube constituting the rung, and shown fitted in this end of the tube in Figure 2 is the insert 13 which acts, in use, as an end plug. The insert is an injection moulded plastics material or metal die cast member having a cylindrical body part 18 sized to fit tightly in the end of the tube. At its one end, the insert is formed with an integral annular skirt portion 19 which is parallel to, but spaced from the body part 18 by the thickness of the tube forming the rung 12, so that, when the insert is fitted in the end of the tube, this tube end engages the junction between the skirt portion and the body portion, which thus acts as a stop to prevent the insert being pushed further into the tube, the skirt portion tightly engaging around the exterior of the tube as shown in Figure 2, so that it is always possible correctly to fit the insert into the end of the tube, for a purpose to be described. As shown, the outer end of the insert can be of any desired form, Figure 2 showing this end with a circular section recess. However this end could, for example, be domed.

As shown in Figure 2, the insert 13 has a diametrai circular section through bore 20 of a diameter slightly greater than that of the holes 15, 16 and 17. As shown in Figure 2, this bore 20 is interrupted approximately at its midpoint by the provision of a cavity 21 which is open to the inner end of the insert and has spaced flat parallel facing surfaces 22, 23 respectively which are normal to the length of the bore 20 and of a diameter greater than that of the bore 20. Received within the cavity 21 between the surfaces 22, 23, is an internally screwthreaded nut 24. When the insert is fitted into the end of the tube constituting the rung 12, it is angularly adjusted so that its bore 20 is in alignment with the bore 17 in the rung 12, as shown in Figure 2. The nut 24 is arranged in the cavity 21 so that the internally threaded bore 25 thereof is also in alignment with the parts of the bore 20 at opposite sides of the cavity 21. Accordingiy it is possible for a fixing element, such as a screw, to be inserted through the holes 15, 16 and 17 so that its shank enters the bore 20 and comes into engagement with the top of the screw-threaded bore 25 in the nut. Figure 2 shows this fixing element in the form of a button-head screw 26 having a domed head 27 and an elongate externally screw-threaded shank 28. The head 27 can be provided with an insert hexagon 29 so that rotation of the screw can only be effected by the use of a suitable Alien key. The head may also have a screwdriver facility, such as a slot or other proprietary form (e.g POZI-DRIVE).

Once the screw 26 has been received through the holes 15, 16, with its shank end having passed through the bore 1 7 and into engagement with the end of the bore 25, the screw can be rotated so that the external thread on the shank 28 engages with the complementary internal thread in the bore 25 so as to draw the end of the shank through the nut 24, given that the nut 24 is prevented from rotation in the cavity 21 by any suitable means. In one embodiment the screw is, for example, secured by adhesive or by other means to the upper and/or lower facing surfaces 22, 23 of the cavity in order to prevent rotation. In another embodiment, the cavity could be provided with walls normal to the facing surfaces 22, 23, which are arranged to engage outer surfaces of the nut 24, so as to prevent rotation. For example in one embodiment, the nut could be of hexagonal external form, with rotation of the nut being prevented by said hexagonal faces engaging correspondingly shaped internal faces of the cavity. It will be appreciated that although it is convenient for the nut to be secured in the cavity, thereby preventing the nut becoming lost and also assuring that it is always correctly positioned to receive the end of the shank 28, the nut could be loose and merely inserted into the cavity, preferably with the insert tipped up to retain the nut against gravity. Alternatively the insert could be formed with some form of projection at the mouth of the cavity, past which the nut can be snapped, the projection thereafter springing back to retain the nut (correctly) within the cavity.

Just before the head 27 of the screw is brought into tight engagement with the outer surface of the upright 10, the orientation between the two tubes can be finally adjusted, for example by swivelling the upright 10 about the axis of the shank 28. It will be appreciated that the two tubes would normally be used at right angles to one another, or substantially so, as shown in Figure 1, but it will be appreciated that the invention also relates to any other orientation between the two tubes, even with them lying parallel and along one another.

When the screw is fully tightened, the head 27 engages the side surface of the upright 10 as shown in Figure 2, with the two tubes engaged together and the nut fully engaged on the end of the shank. For the sake of clarity Figure 2 does in fact show the two tubes slightly spaced apart but, in use, these would be in tight engagement, with the screw tightened to its full extent permissible for this engagement.

Accordingly it can be seen that with this invention many of the disadvantages of the prior art referred to in the introduction are overcome. Firstly the end of the shank, and the nut, are now concealed, so that only the head of the screw protrudes from either of the tubes.

This head can of course be covered by a suitable cap, ferrule or the like.

Secondly only this screw head, either covered or uncovered, is visible, and it can be arranged that this is at the rear of the assembly, as shown in Figure 1 for the rung relative to the two uprights. Thus visually the arrangement is much more pleasing than that of the prior art. Thirdly the insert not only acts as a end cap to close the tubular rung, but it also takes part in the fixing assembly and provides a fourth advantage, in that it enables the nut to be concealed and hidden from the exterior. Since it is only possible to undo the screw by means of a particular tool, such as an Allen Key (i.e. a hexagon wrench), the potential for vandalism is much reduced.

It will be appreciated that instead of a nut in the insert to provide the screw thread for engagement by the shank 28, the insert could itself be formed with an integral internal screw thread, for example on the inside of at least part of the bore 20 for engagement by the thread on the shank 28. It will also be appreciated that if the holes 15, 16 are adjacent the end of the upright 10, this end could be closed by a similar insert with a through bore through which the shank 28 passes to hold the insert as an end cap at the end of the upright 10. The through passage in such an insert of the upright 10 could be unthreaded or could provide a thread either integrally or by way of a nut, if required.

Figure 3 is a schematic diagram showing an upright tube 30 with upper and lower tubular assemblies connected across it. The lower assembly comprises a first tube 31 into which is fitted the swaged end of a second co-axial tube 32. It can be seen that here the insert 33 fitted in the end of the tube 32 has a head which is of the same outside diameter as that of the swaged end of the tube 32, and of the internal diameter of tube 31. An internal view of this fitting is shown schematically in Figure 4 with the combined thicknesses of the two tubes 31,32 respectively shown as one thickness. Respective holes in the tubes 31 and 32 are axially and radially aligned for reception of the fixing screw from tube 30. It can be seen that the detail of the insert is somewhat different from the one shown in Figure 2, in that the nut 34 is in a first cavity which is spaced from a second cavity 35 into which the end of the shank of the screw would project if this were longer than that shown in the Figure.

The upper tubular assembly also shows how an insert 36 of double ended form could be used at a junction between two tubes with nonswaged ends, such as a tube 37 and an adjoining co-axial tube 38, the insert in this embodiment providing a pair of internal screw threads which can be parallel, as shown, or, alternatively for example, normal to one another, to enable variations of attachments of respective tubes to tubes 37 and 38. It can be seen that here the insert 37 is provided with a central peripheral annular flange 39 which is received between the respective ends of the two tubes which are juxtaposition, so that for both tubes, the insert acts as an end cap.

As illustrated, the insert 36, which is of the same or similar form to that of Figures 2 and 4, is used to connect tube 37 to tube 30. However it could of course be used to connect tube 38 to tube 30 instead, or could be used to connect one further tube to tube 37 and simultaneously another further tube to tube 38, the further tubes, for example, being at opposite sides of tubes 37, 38 respectively. The insert could of course be used with only a single one of its ends received in a tube, but normally in such a case an insert with a projecting body part at only one side of its head, such an insert 1 3 or 33, would be used. Shown at this fixing is an alternative orientation of the tube 30, denoted by the numeral 30a, where the tube is at an angle to the tube 37.

Finally Figures 5 and 6 show the interior configurations of respective inserts 41, 42 respectively in a tube 40, these inserts each being for engagement with a 40mm bolt, but with the Figure 6 insert being for use with a larger diameter tube.

Instead of the side surfaces of the connected tubes engaging, one or more intermediate members could be arranged therebetween with the shank of the bolt 28 passing therethrough. Such members include tubes and spacing elements. Such members could also be arranged between the bolt head 27 and the tube equivalent to tube 10.

Claims

1. A method of connecting together two elongate members, one of which has a transverse or generally transverse bore defined therethrough, and the other of which has a discrete transverse or generally transverse bore extending to an internal tubular part thereof, which is in communication with an open end of said other elongate member, the method comprising engaging in said open end an insert which forms an end plug which extends to said tubular part, within which it provides a screw-thread, arranging the two members so that the bore defined through said one member is aligned with the discrete bore of the other member, passing a headed fixing element through said bore defined through said one member and said discrete bore of the other member so that a screw-thread of the fixing element initially engages the screwthread provided by the insert, and screwing up said fixing element so that part thereof is held in said insert, thereby to connect the two members together.

2. A method as claimed in Claim 1, wherein the fixing element is screwed up until respective outer side surfaces of the two members engage.

3. A method as claimed in Claim 1 or Claim 2, wherein the fixing element is screwed up until the head of the fixing element engages against said one member.

4. A method as claimed in any one of Claims 1 to 3, wherein the insert is engaged in said open end so that a skirt portion of the insert engages the outer side surface of said other member.

5. A method as claimed in any one of Claims 1 to 3, comprising forming said other member as a tubular assembly by engaging within an open end of a first tube a swaged end of a second tube having said insert engaged therein, and passing said fixing element through said one member and through respective aligned holes in said first and second tubes to engage the screw thread of said insert in said second tube.

6. A method as claimed in any one of Claims 1 to 3, comprising providing said insert as a doubleended cap having a screw-thread in each end portion thereof, engaging respective open ends of said other elongate member and a further elongate member onto said respective end portions of the cap, and engaging said one elongate member with a selected one of said other elongate member and said further elongate member by engagement of said fixing element with the screw thread provided in said selected other or further elongate member.

7. An assembly comprising two connected elongate members, one member having a transverse or generally transverse bore defined therethrough, the other member having a discrete transverse or generally transverse bore extending to an internal tubular part thereof which is normally in communication with an open end of said other elongate member, an insert engaged in said open end to form an end plug which extends to said tubular part, within which it provides a screw-thread, and a headed fixing element received through said bore defined through said one member and said discrete bore of the other member, and being screw-threadedly engaged with said insert by means of said screw-thread thereof.

8. An assembly as claimed in Claim 7, wherein respective outer side surfaces of said two members are in engagement.

9. An assembly as claimed in Claim 7 or Claim 8, wherein the head of the fixing element is in engagement with said one member.

10. An assembly as claimed in any one of Claims 7 to 9, wherein the end plug has the periphery of its head matching the external periphery of said open end of said other member.

11. An assembly as claimed in any one of Claims 7 to 9, wherein the insert has a skirt portion spaced outwardly from the part of the insert received within the end of said other member and engaging the outer side surface of said other member.

12. An assembly as claimed in any of Claims 7 to 9, wherein said other member is a tubular assembly formed by the engagement within an open end of a first tube a swaged end of a second tube having said insert engaged therein, and said fixing element passes through said one member and through respective aligned holes in said first and second tubes to engage the screw thread of said insert in the second tube.

13. An assembly as claimed in Claim 17, wherein the head of the insert has its periphery matching the external periphery of said swaged end of the second tube, and the internal surface of said first tube.

14. An assembly as claimed in any one of Claims 7 to 9, wherein two of said other members are co-axially interconnected by said insert in the form of a double-ended cap providing a screw thread in each end, said one member being connected to a selected one of the two interconnected other members by engagement of said fixing element with the screw thread in the end of the insert within said selected other elongate member.

15. An assembly as claimed in Claim 14, wherein respective adjacent ends of the two other members abut respective opposite sides of a lateral flange of the double-ended cap.

16. An assembly as claimed in Claim 14 or Claim 15, wherein two of said one elongate members are connected to respective ones of said interconnected other members by engagement of respective fixing elements with respective screw threads in said interconnected other members.

1 7. An assembly as claimed in any one of Claims 7 to 17, wherein the screw thread is provided by a nut held against rotation in a cavity of the insert.

18. An assembly as claimed in Claim 17, wherein the nut is held against rotation by adhesive securement in said cavity.

19. An assembly as claimed in Claim 17, wherein the nut is held against rotation by engagement of side surfaces of the nut with respective corresponding surfaces of the cavity.

20. An assembly as claimed in Claim 17, wherein the nut is held in said cavity by a snap-fit.

21. An assembly as claimed in any one of Claims 1 7 to 20, wherein the insert has a bore therein extending from one outer side surface thereof to said cavity, through which the fixing element is received.

22. An assembly as claimed in Claim 21, wherein the bore is a trough bore continuing from said cavity to another outer side surface of the insert opposite to said one side surface.

23. An assembly as claimed in any one of Claims 7 to 16, wherein the screw thread is formed on the interior of a bore through at least part of the insert.

24. An assembly as claimed in any one of Claims 7 to 23, wherein the head of the fixing element is adapted for engagement only by other than a screwdriver.

25. An assembly as claimed in any one of Claims 7 to 24, wherein the members are hollow circular section tubes and the insert is cylindrical.

26. A method of connecting together two elongate members substantially as hereinbefore described, with reference to, and as shown in Figures 1 and 2, or Figures 3 and 4 of the accompanying drawings.

27. An assembly comprising two connected elongate members, substantially as hereinbefore described, with reference to, and as shown in Figures 1 and 2, or Figures 3 and 4, or Figure 5 or Figure 6 of the accompanying drawings.