GB2470116A

GB2470116A - Tube fitting

Info

Publication number: GB2470116A
Application number: GB1007435A
Authority: GB
Inventors: David Meecham
Original assignee: DALEN Ltd
Current assignee: DALEN Ltd
Priority date: 2009-05-05
Filing date: 2010-05-05
Publication date: 2010-11-10
Also published as: GB201007435D0; GB0907621D0

Abstract

A tube fitting 14 comprises a base plate 24 and at least one arm 26 connected to the base plate 24, the arm 26 having at least one threaded aperture. The threaded aperture can be formed into the arm 26, or can be provided by a threaded bush, a captive nut, a hank bush 30, or a threaded rivet, mounted at a chosen position upon the arm 26.

Description

TUBE FITTING

FIELD OF THE INVENTION

This invention relates to a tube fitting, and in particular to a fitting for a tube permitting the tube to be more easily fixed to a bracket or other component.

BACKGROUND TO THE INVENTION

Tubes are in widespread use for supporting or mounting articles, and as part of larger structures. It is a common requirement that the end of a tube must be secured to a bracket or other component.

is For brevity, the following description refers to the securement of the end of the tube to a bracket, and it will often be the case that the end of the tube is fitted to a bracket prior to securement of the bracket to another component. However, it is to be understood that the end of the tube could be secured directly to a component other than a bracket, for example to another tube, without departing from the scope of the present invention.

Also, the tubes referred to in the following description are substantially circular in cross-section, and whilst it is expected that the invention will find its greatest utility in relation to such tubes, it will be understood that the invention is equally applicable to tubes having rectangular, oval or other shape in cross-section.

Furthermore, whilst the invention is likely to find its greatest utility in relation to metallic tubes, it will be understood that it is equally applicable to tubes of plastic or other materials.

One method of securing the end of a tube utilises a bracket having a mounting plate to which is connected two upstanding side walls, the side walls being spaced apart by a distance slightly greater than the diameter of the tube, so that the end of the tube can lie between the side walls. The side walls have mounting holes formed therethrough and the opposed sides of the tube have corresponding mounting holes.

Fastening means such as a bolt or screw can be passed through the mounting holes in the side walls of the bracket and through the aligned mounting holes in the opposed sides of the tube so as to secure the tube to the bracket. The mounting plate of the bracket also has holes permitting the bracket, and thereby the tube, to be secured to another component so as to complete or continue the structure. The mounting plate is shaped to cooperate with the other component, for example being substantially flat in the event that the bracket is to be secured to a flat wall or other surface.

The bracket will often be formed as an integral pressed or stamped part, with the side walls being joined to the base plate by respective fold lines.

In a first method of securement the material from which the tube is made is sufficiently thick and rigid to support a thread, and bolts or screws are passed through the mounting holes in the bracket and secured into threaded mounting holes in the tube. This method is not typical, however, as it is usually the case that the tube material is not sufficiently thick or sufficiently rigid to support a thread, and another means must be provided to secure the tube.

A second method is to pass a bolt across the tube, so that a single bolt engages both side walls of the bracket to the opposed sides of the tube. This method avoids the requirement to provide a thread on the mounting holes in the tube, and instead allows the tube to have punched or drilled holes therethrough. However, this method has two significant disadvantages. The first disadvantage is that the securement provided is dependent upon the force with which the nut or other fastening is tightened onto the bolt. As the nut is tightened it acts to compress the tube, and the tube must be sufficiently strong to withstand that compression. With tubes made of thin wall section this method is not always suitable because the tube may deform as the nut is tightened, so that the nut cannot be tightened sufficiently to prevent the tube moving relative to the bracket.

A second disadvantage is that the bolt spans the inside of the tube, and presents an obstacle to any wiring or the like which is to be passed along the inside of the tube.

Tubes are often used as part of a structure to mount or secure articles of electrical equipment and it is a recognised advantage that the electrical wiring for the equipment can be passed along the tube and avoid the wiring presenting a visual or physical encumbrance.

In order to avoid these disadvantages, operators have sought to utilise a third method in which a nut is manually inserted into the tube, and held underneath the mounting hole in the tube whilst the bracket is located and a bolt inserted. Whilst this third method avoids the two disadvantages of the second method described above, it has its own disadvantages. Firstly, with tube of smaller diameter than the operator's fingers it is not possible to insert the required nut or nuts manually, and a specialised tool is required. The requirement for a specialised tool increases the complexity and cost of the operation. Secondly, it is not usually possible, by finger pressure alone, to hold the nut against rotation as the bolt is tightened, and instead it is necessary to fit a spanner or other tool into the tube in order to hold the nut against rotation.

Often, a plurality of nuts will be used, and access to at least one of the nuts may be limited by the other nuts and fitted bolts. Also, it will be understood that this is an operation requiring considerable dexterity, which cannot always be achieved quickly and efficiently, especially with the tubes commonly used for supporting or mounting electrical equipment which typically have a diameter only slightly larger than the thickness of the operator's fingers.

A fourth method utilises captive nuts welded to the inside of the tube underneath the mounting holes which have been formed therein. This method also avoids the two disadvantages of the second method described above, but again has its own disadvantages. Firstly, it is difficult and relatively expensive to weld the required number of nuts into their correct position within a tube which may be of relatively small diameter. Secondly, the advantage of the method is lost if the tube has to be cut on site.

It is not uncommon for a tube which is to be secured to another component to require cutting on site, and the ability of an operator to cut the tube to fit a particular location or application is often a desirable attribute. In one example, it is known to use a tube as part of the structure for mounting a projector to a ceiling; if a long tube is provided which the operator can cut to the required length on site the operator will not need to visit the site in advance in order to measure the height of the ceiling and determine the length of tube required. In addition, the tube manufacturer will be unlikely to make, and retain stock of, a large number of tubes having captive nuts which differ only in length.

Despite the advantages of providing captive nuts therefore, many operators will still prefer to use the second and third methods described above, and to tolerate their disadvantages. Thus, many operators still choose to cut the tube to length on site, and simply drill the required mounting holes.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a tube fitting which can permit a tube to be more easily fixed to a bracket or other component, whilst avoiding or reducing the above-stated disadvantages.

According to the invention there is provided a tube fitting comprising a base plate and at least one arm connected to the base plate, the arm having at least one threaded aperture.

The threaded aperture can be provided by a captive nut or the like, for example a hank bush or a threaded rivet. The tube fitting is constructed in such a way that the arm can be inserted into the end of the tube to be secured, with the threaded aperture underlying a mounting hole in the tube wall. The tube fitting therefore provides the threaded element to which a bolt or other fastening can be secured, thereby permitting the tube to be secured to a bracket by way of aligned mounting holes in the tube and bracket.

Preferably, the tube fitting has two arms connected to the base plate, the spacing between the arms at their connection to the base plate being only slightly smaller than the inside dimension of the tube. Accordingly, both arms can be inserted into the end of the tube, and the threaded aperture(s) of each arm can lie underneath a mounting hole in the opposed sides of the tube. Desirably, the tube fitting is resilient, and the two arms are formed to diverge slightly away from the base plate.

Accordingly, it is necessary to press the free ends of the arms together before they can be inserted into the end of the tube, and the resilience of the tube fitting will act to hold the tube fitting in position within the end of the tube until the fastenings are inserted.

Preferably, the base plate has a dimension greater than the internal dimension of the tube, so that the base plate cannot be inserted into the tube and instead abuts the end of the tube. It is arranged that the distance between the base plate and the threaded aperture(s) match(es) the distance between the end of the tube and the hole(s) formed therein. Accordingly, inserting the tube fitting into the end of the tube until the base plate engages the end of the tube, and with the threaded aperture(s) aligned with the mounting hole(s), will ensure that the threaded aperture(s) lie(s) underneath the mounting hole(s).

Preferably, the base plate is apertured, so that it does not span the end of tube, and instead permits an electrical wire or the like to be passed along the tube.

Ideally, the tube fitting is metallic, and is made as a pressing or stamping, with the arm(s) being integrally connected to the base plate by a respective fold line. The metal from which the tube fitting is made may be sufficiently thick and sufficiently rigid to support a thread, in which case the threaded aperture(s) can be formed directly in the material. Preferably, however, the threaded aperture(s) are provided by separate threaded bushes or captive nuts secured by welding or the like to the arms of the tube fitting.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will now be described in more detail, by way of example, with reference to the accompanying drawing, which shows an exploded view of the end part of a tube to be secured to a bracket by way of a tube fitting according to the present invention.

DETAILED DESCRIPTION

Fig.1 shows a tube 10 which is to be fitted to a bracket 12 by way of a tube fitting 14 according to the present invention. It will be understood from the following description that the tube fitting 14 is designed to fit the tube 10, and that a different size and form of tube fitting could be used with a different tube. Also, the form of the bracket 12 is irrelevant to the present invention, and the bracket 1 2 could be replaced by another form of bracket, or another component; it is only necessary that the bracket 12 has mounting holes 16 which correspond with the mounting holes 20 in the tube 10.

The mounting holes 20 in the tube 10 are drilled or punched, and are therefore not threaded. If the tube 10 has been cut to length on site the mounting holes 20 will also be drilled on site, and a template would typically be provided to ensure that the mounting holes 20 are drilled with the correct separation, and at the correct distance from the end 22 of the tube 10.

Four mounting holes 20 are formed through the tube wall, although only two are visible in Fig.1. In other embodiments there could be more or fewer mounting holes 16, 20, as desired.

The tube fitting 14 of the present invention comprises a base plate 24 and two arms 26. Each of the arms 26 carries two hank bushes 30, each of the hank bushes providing a threaded aperture. It will be understood that in other embodiments the threaded apertures could be provided by nuts welded or otherwise made captive upon the arms, or the material of the arms could be sufficiently thick and sufficiently rigid to support a thread.

The number of, and spacing between, the threaded apertures 30 on each arm 26 matches the number of and spacing between the mounting holes 20, and the distance between the threaded apertures 30 and the base plate 24 matches the spacing between the mounting holes 20 and the end 22 of the tube 10.

In this preferred embodiment the base plate 24 is substantially circular, and has a diameter slightly greater than the internal diameter of the tube 10, so that the base plate 24 cannot enter the tube 10 and instead abuts the tube end 22. This construction permits the base plate 24 to provide a positive location for the threaded apertures 30 matching the longitudinal position of the mounting holes 20, and it is only necessary for the operator to rotate the tube fitting 14 relative to the tube 10 to align the threaded apertures 30 with the mounting holes 20 in order to ensure that the threaded apertures 30 lie underneath the respective mounting holes 20. If desired, the mounting holes 20 can be of substantially larger diameter than the mounting holes 16 and the threaded apertures 30, 50 as to provide some tolerance in the relative positioning of the tube fitting 14 within the tube 10, although the mounting holes 20 should not be so large as to undermine the securement provided.

In the embodiment shown the tube fitting 10 is made from metal and has some resilience. Also, whilst the separation between the arms 26 closely matches the internal diameter of the tube 10 at their connection to the base plate 24, the arms 26 are formed to be slightly diverging away from the base plate 24. Alternatively stated, the free ends 32 of the arms 26 are initially separated by a distance slightly greater than the internal diameter of the tube 1 0. This requires the operator to press the free ends 32 together in order to insert the arms 26 into the tube 10, and once inserted and the free ends 32 released the resilience of the material is sufficient to hold the tube fitting 14 temporarily in place within the tube 10.

Once the tube fitting 14 has been inserted into the tube 10, the tube 10 is inserted between the side walls 34 of the bracket 12, so that the mounting holes 16 in the bracket 1 2 align with the mounting holes 20 in the tube 1 0. Suitable fasteners, in this embodiment bolts 36, are then inserted through respective mounting holes 16, 20 and into a hank bush 30. The bolts 36 can be tightened so as to secure the tube 10 to the bracket 12.

It will be understood that the wall of the tube 10 is sandwiched between an arm 26 of the tube fitting 14 and the side wall 34 of the bracket 12; the bolts 36 can be fully tightened without risk of deforming the tube. Also, the bolts 36 can be relatively short, so that they do not project (or at least do not project very far) into the tube 10 beyond the hank bushes 30, so that the obstacle to wiring or the like being passed along the tube 10 is minimised.

In this latter regard, it will also be noted that both the base plate 24 and the centre of the mounting plate 40 of the bracket 12 are apertured, to permit the passage of wiring or the like along the tube 10.

It will be understood that the presence of an aperture in the base plate 24 results in the base plate 24 comprising a ring of material, and in the embodiment shown the ring is relatively narrow. That is of no consequence to the tube fitting 14 being able to perform its function, however, as the tube fitting 14 does not require much structural strength, and it is sufficient for the tube fitting 14 to perform its function that the threaded apertures 30 are sufficiently robust to permit the bolts 36 to be made very tight.

In fact, however, providing the base plate as a relatively thin ring can be desirable in embodiments in which the base plate and arms are formed as a pressing or stamping from a single sheet of material. Thus, it will be understood that respective parts of the ring form the connections between the base plate and the arms, and if the ring is narrow the material can be readily folded or twisted to form the tube fitting into its required "U" shape. It has also been found that a relatively thin ring of material will provide a reliable location at which the material folds or twists, so that the separation of the arms 26 at their connection to the base plate 24 can easily be controlled without requiring complex jigs and fixtures.

The embodiment shown has two arms 26, and the bracket 12 has two side walls 34, but it will be understood that the invention is equally applicable to embodiments in which the tube fitting has only one arm and the bracket has only one side wall. Such embodiments are likely to be rare, however, as it is generally preferred to secure the tube by way of diametrically opposed fastenings, requiring two arms and two side walls.

Claims

CLAIMS1. A tube fitting comprising a base plate and at least one arm connected to the base plate, the arm having at least one threaded aperture.
2. A tube fitting according to claim 1 in which the tube fitting has two arms connected to the base plate.
3. A tube fitting according to claim 1 or claim 2 in which the arms and base plate substantially form a "U" shape.
4. A tube fitting according to claim 3 in which the spacing between the arms at their connection to the base plate is slightly smaller than the inside dimension of a tube with which the tube fitting is designed to fit.
5. A tube fitting according to any one of claims 2-4 in which the tube fitting is resilient, and the two arms are formed to diverge slightly away from the base plate.
6. A tube fitting according to any one of claims 1-5 in which the base plate has a dimension greater than the internal dimension of a tube with which the tube fitting is designed to fit.
7. A tube fitting according to claim 6 in which the distance between the base plate and the threaded aperture is determined to match the distance between the end of the tube and a hole formed in the tube.
8. A tube fitting according to any one of claims 1-6 in which the base plate is apertu red.
9. A tube fitting according to any one of claims 1-8 made of metal.
10. A tube fitting according to claim 9 made as a pressing or stamping, with the arm(s) integrally connected to the base plate by a respective fold line.
11. A tube fitting according to any of claimsi-lO in which the material from which the tube fitting is made is sufficiently thick and sufficiently rigid to support a thread.
1 2. A tube fitting according to any one of claims 1 -1 0 in which the or each threaded aperture is provided by a threaded bush, a captive nut, a hank bush, or a threaded rivet, which is secured to the arm.
13. A tube fitting according to any one of claims 1-12 having two arms, with each arm having two threaded apertures, each of the threaded apertures in one of the arms being aligned with a respective threaded aperture in the other arm.
14. A tube fitting according to any one of claims 1-13 in which the base plate is is substantially in the form of a ring.
1 5. A method of making a tube fitting comprising the steps of: {i} providing a substantially planar sheet of a chosen material; {ii} cutting the material to provide a substantially planar tube fitting blank comprising the base plate and the at least one arm; {iii} bending the or each arm through approximately 9O relative to the base plate; {iv} providing at least one threaded aperture at a chosen position upon the or each of the arms.
16. A method according to claim 15 in which step {iv} is carried out before step {iii}.
17. A method according to claim 15 or claim 16 in which the step of providing at least one threaded aperture comprises securing a threaded bush, a captive nut, a hank bush, or a threaded rivet, at a chosen position upon the arm.
18. A method according to any one of claims 14-17 in which the form of the blank determines the position at which the arm(s) will bend.
19. A method according to claim 18 in which the form of the blank is chosen to have one or more regions of relative weakness at which the arm(s) will bend.
20. A tube fitting constructed and arranged substantially as described in relation to the accompanying drawing.