GB2473492A

GB2473492A - Intermediate fixing for a cable basket tray

Info

Publication number: GB2473492A
Application number: GB0916085A
Authority: GB
Inventors: Andrew Booth
Original assignee: Ellis Patents Ltd
Current assignee: Ellis Patents Ltd
Priority date: 2009-09-15
Filing date: 2009-09-15
Publication date: 2011-03-16
Anticipated expiration: 2029-09-15
Also published as: GB0916085D0; GB2473492B

Abstract

A fixing device 1 for facilitating the attachment of an object to a mesh or grid 100 comprises a first portion 10 and a second portion 20 permanently connected together to form a gap between the portions, two concentric holes 12 allowing a bolt to pass through the two portions and where at least one of the portions has a lip 14 arranged to engage the mesh to secure the device at an intersection of the mesh. The device is secured by the presence of the lip but can also include additional lips or notches along the edge of the device to further engage with the mesh members. This allows the device to facilitate the retaining or attachment of cables to a cable basket tray via a suitable cable cleat or clamp. The strength of the attachment is strong enough to prevent the oscillation or movement of a three phase power cable caused by the forces produced during a short circuit.

Description

INTEPNEDIATE FIXING FOR A SH

An embodiment of the present invention relates to an intermediate fixing for a mesh, in particular an intermediate fixing for facilitating the attachment of a cable cleat to a basket tray.

In the construction of buildings, cables, including data cables, power cables and telephone cables, must be installed securely, safely and tidily. It is currently known to use both cable ladders and cable basket trays to facilitate such installations. Cable ladders and cable basket trays may either be directly attached to a fixed structure, such as a floor, ceiling or wall, or they may be suspended from a fixed structure using either rigid or flexible hangers.

Cable ladders comprise a pair of parallel members that are attached together using a number of rungs arranged perpendicularly to the parallel members. Cable ladders often come in 3m sections that must be joined together to form the required length of ladder.

Cable basket trays comprise a wire mesh basket having a horizontal base and two vertical sides. The wire mesh comprises a plurality of first wire members and a plurality of second wire members that are arranged perpendicularly to the first members. The second members are bent into a shallow U-shape to provide the base and the two sides, and the first members are welded to the second members at each intersection. Similarly to cable ladders, cable basket trays are often provided in 3m sections that must be joined together to form the required length of basket.

There are various advantages and disadvantages associated with cable ladders and cable basket trays.

Whilst cable ladders are stronger and more rigid than cable basket trays, cable basket trays are cheaper and lighter and are therefore easier to suspend. For the aforementioned reasons, cable ladders tend to be used to support three-phase cables carrying large currents whereas cable basket trays tend to be used to support smaller power cables and data cables. A further factor in this decision is that for a tidy and safe installation, the cables must be attached to either the cable ladder or cable basket tray. In the case of small power cables and data cables this can be accomplished simply by using nylon or stainless steel cable ties. However, three-phase power cables carrying large currents must be restrained by a cable cleat. This is because in the event of a short circuit, large oscillating forces occur between the cables. Cable cleats usually comprise a base member and a means for retaining one or more cables. In order for the cable cleat to perform effectively, the base member must be securely attached to a fixed structure. In some instances a cable cleat is simply attached to a wall, for example. When cable ladders or cable basket trays are used to support cables, the cable cleat must be securely attached to the cable ladder or basket tray. Due to the structure of a cable ladder rung, a cable cleat may be directly fastened to it using a bolt, for example. However, when using a cable basket tray it is not possible to directly attach a cable cleat to it due to the overlapping mesh structure of the basket tray. For this reason, cable basket trays are not usually used to support three-phase power cables requiring a cable cleat.

If it is desirable to attach a cable cleat, or any other component, to a cable basket tray, or any type of mesh structure, then an intermediate fixing must be used.

One known type of intermediate fixing for a mesh comprises two discrete plates, each having a lip at either end and hole through the centre. The mesh is sandwiched between the two plates and the plates are arranged perpendicular to each other so that the lips of the first plate engage with two parallel and adjacent first members and the lips of the second plate engage with two parallel and adjacent second members, the first members and second members being perpendicular. Whilst this arrangement is acceptable in some arrangements, it has a number of drawbacks.

Firstly, two separate parts are required. This results in a relatively high manufacturing cost and it also means that assembling the intermediate fixing requires careful alignment to ensure that the lips engage the correct members of the mesh and that the holes are properly aligned. Secondly, if large oscillating forces are applied to the intermediate fixing via the object attached to it, as occurs when a three-phase cable short-circuits, the intermediate fixing may be displaced from its desired position.

It is therefore desirable to provide an intermediate fixing for a mesh which can be manufactured and assembled with ease and which is secure even when subject to large oscillating forces.

According to one aspect of the present invention there is provided a fixing device for facilitating the attachment of an object to a mesh, the mesh having a plurality of first members and a plurality of second members wherein the first members are perpendicular to the second members, the fixing comprising: a first part (or portion) having a first hole; and a second part (or portion) having a second hole; wherein: the first part and the second part are permanently connected together to form a gap between the first and second parts; the first hole and second hole are substantially concentric so as to allow a bolt to pass through them; at least one of the first and second parts has a lip that extends over a portion of the width of the said part; and the lip is arranged to engage with a first member of the mesh to retain the fixing device at an intersection point of the mesh.

The gap formed between the two parts may be substantially constant. The first part and the second part may be in the form of plates and the first part and second part may be integrally formed.

In one embodiment the lip comprises a first lip formed on the first part; the first lip may be formed on a side that is opposite from a side that is connected to the second part. Further, the first part may further comprise a second lip that extends over a portion of the width of the first part; the second lip may be formed on the same side of the first part as the first lip; the second lip may be spaced apart from the first lip so as to form a notch; and the notch may be arranged to engage the first member.

In one embodiment lip may comprise a lip formed on the second part; the lip may be formed on the same side as the side that is connected to the first part; and the lip may be arranged to engage a second member in addition to the first member. In one embodiment there is a lip formed on both the first part and the second part. In one embodiment there are two lips on the first part and one lip on the second part.

The second part may also comprise a notch formed between the lip of the second part and the connection between the first and second parts; the notch may be arranged to engage the first member.

According to a second aspect of the present invention there is provided a system for supporting at least one power cable comprising: a cable basket tray comprising a mesh having a plurality of first members and a plurality of second members, wherein the first members are perpendicular to the second members; a fixing device according to any statement herein, wherein a portion of the mesh is located within the gap between the first part and the second part and the lip is engaged with a first member of the mesh; and a cable retaining device retaining the at least one cable, wherein the cable retaining device is attached to the fixing device by a fixing that passes through the first hole of the first part and the second hole of the second part.

According to a third aspect of the present invention there is provided a method of supporting at least one power cable, comprising the steps: attaching a fixing device according to any statement herein to a cable basket tray comprising a mesh, the mesh having a plurality of first members and a plurality of second members wherein the first members are perpendicular to the second members, such that a portion of the mesh is located within the gap between the first part and the second part and the lip is engaged with a first member of the mesh; attaching a cable retaining device to the fixing device by a fixing that passes through the first hole of the first part and the second hole of the second part; securing the cable retaining device to the fixing device by tightening the fixing; and securing the at least one cable within the cable retaining device.

The invention may comprise any combination of the features and/or limitations referred to herein, except combinations of such features as are mutually exclusive Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 schematically shows a perspective view of a first embodiment of a fixing device; Figure 2 schematically shows a cross-sectional view of the fixing device shown in Figure 1; Figure 3 schematically shows a perspective view of the fixing device shown in Figure 1 attached to a mesh; Figure 4 schematically shows a side view of the fixing device shown in Figure 1 attached to a mesh using a bolt; Figure 5 schematically show a perspective view of the fixing device shown in Figure 1 used to attach a cable cleat to a mesh; Figure 6 schematically shows a stamped piece of steel that may be folded into the fixing device shown in Figure 1; Figure 7 schematically shows a perspective view of a second embodiment of a fixing device; Figure 8 schematically shows a perspective view of a third embodiment of a fixing device; Figure 9 schematically shows a perspective view of a fourth embodiment of a fixing device; and Figure 10 schematically shows a perspective view of a fifth embodiment of a fixing device.

Referring to Figures 1 and 2, a fixing 1 comprises a first part 10 and a second part 20. The first part 10 and second part 20 are formed from a single piece of plate metal. The method of manufacture will be discussed later.

The first part 10 is arranged so as to be substantially parallel to the second part 20. This forms a substantially constant gap between the two parts 10, 20. The first part has a first hole 12 that is in the plane of the first part. Similarly, the second part 20 has a second hole 22 that is in the plane of the second part. The first and second holes 12, 22 are arranged to be substantially concentric with each other in as much as a bolt, or similar fixing device, can be passed through them both.

The first part 10 comprises a first lip 14 and a second lip 18. The first and second lips 14, 18 are formed on a side of the first part 10 that is opposite the side that is attached to the second part 20. The first and second lips 14, 18 are substantially perpendicular to the first part 10 and extend from the first part 10 towards the second part 20. The first lip 14 and the second lip 18 extend over a portion of the width of the first member 10 and are spaced apart from one another so as to form a notch 16. The width of the first lip 14 is smaller than the width of the second lip 18 and hence the notch 16 is offset from the centre of the first part 10. The second part 20 comprises a lip 24 that is formed on the same side of the second part 20 that is attached to the first part 10. The lip 24 extends over a portion of the width of the second member 20 arid extends towards the first part 10. A notch 26, or gap, is formed between the lip 24 and the connection 30 between the first part 10 and the second part 20. The first part 10 also has a cut-out 19 that is located in a region above the lip 24 and notch 26 of the second part 20.

The width of the first part 10 and the width of the second part 20 are substantially the same. The length of the second part 20 is less than the length of the first part 10. This difference in length provides an opening 29 between the first and second lips 14, 18 of the first part and the second part 20.

Figure 3 shown the fixing device 1 attached to a mesh 100. The mesh 100 may be a cable basket tray. The mesh comprises a plurality of first members 110 that are equally spaced and arranged parallel to each other, and a plurality of second members 120 that are also equally spaced and arranged parallel to each other. The plurality of first members 110 are arranged perpendicularly to the plurality second members 120 and are welded together at each intersection 130.

The fixing device 1 may be attached to the mesh 100 as follows. The opening 29, defined by the gap between the first and second lips 14, 18 of the first part 10 and the second part 20, is aligned with a second member 120 of the mesh. The first and second lips 14, 18 of the first part are then hooked over the second member 120. The fixing member is then slid in the direction of extension of the second member 120 towards a first member 110 so that the side of the first lip 14 of the first part 10 is in contact with the first member 110.

The fixing device 1 is then rotated clockwise whilst lifting the first lip 14 of the first part 10 over the first member 110 so that the first member 110 is located in, or engaged with, the notch 16 of the first part 10.

The fixing device 1 is then rotated anti-clockwise so that the first member 110 is also located within, or engaged with, the notch 26 of the second part 20. The fixing device 10 is then slid in the direction of extension of the first member 110 so that connection 30 between the first part 10 and the second part 20 and the lip 24 of the second part is in contact with the second member 120.

In this position, the side of the first lip 14 of the first part 10 is engaged with the first member 110 and the first member 110 is located within the notch 16. The side of the second lip 18 of the first part 10 is spaced apart from the first member 110 because the notch 16 is wider than the first member 110. Although the edge of the second lip 18 of the first part 10 is not in direct contact with the first member 110 of the mesh 100, upon clockwise rotation of the fixing device 1, the edge of the second lip 18 of the first part 10 comes into contact with the first part and prevents further rotation.

Further, the side of the lip 24 of the second part 20 is engaged with the first member 110 and the first member is located within the notch 26. Also, the side of the connection 30 between the first part 10 and the second part 20 is engaged with the first member, and the second member is located in the connection 30 between the first part and the second part 20. The intersection 130 between the first member 110 and the second member 120 is located below the opening 19 in the first part 10.

Axes x, y and z are illustrated in Figure 3. The z-axis is defined as being perpendicular to the plane of the mesh 100, the x-axis is defined as being in the plane of the mesh 100 in the direction of extension of the second member 120, and the y-axis is defined as being in the plane of the mesh 100 in the direction of extension of the first member 120. With reference to these definitions, the fixing device 1 is prevented from moving up (+z) or down (-z) due to a portion of the mesh being located between the gap defined by the first part 10 and the second part 20.

The fixing device 10 is prevented from moving right (+x) or left (-x) due to the first member 110 being engaged with lips 14, 18, 24 (and hence being located within notches 16 and 26) and with the side of the connection 30. The fixing member 1 is also prevented from moving forwards (+y) due to the second member 120 being located within the connection between the first part 10 and the second part 20. The only direction that the fixing device 1 can move in is backwards (-y) . Movement in this backwards direction (-y) is prevented by passing a bolt, or similar fixing, through the first hole 12 of the first part 10 and the second hole 22 of the second part 20. Thus, the fixing device is prevented from moving forwards (y), backwards (-y), up (z), down (-z), right (x) and left (-x) In use, an object, such as a cable cleat, is attached to the mesh 100 via the fixing device 1 by means of a bolt 220 or other suitable fixing. For illustration purposes Figure 4 shows the bolt 220 but no object. In order to attach an object (not shown) to the mesh 100, the fixing device 1 is moved to the position described above and a bolt 220 is passed through a mounting portion on the object, the first hole 12 of the first part 10 and the second hole 22 of the second part 20. A nut 240 is then threaded onto the end of the bolt 220 and tightened. The bolt 220 and nut 240 are tightened causing the fixing device 1 to deform slightly. This deformation is in the form of the first part 10 and second part 20 becoming closer together through a reduction in the radius of connection 30. As such, the gap between the first part 10 and the second part 20 becomes smaller (and is no longer constant) and thus the fixing device 1 is more held on the mesh 100 more securely. This in turn ensures that the object attached to the mesh 100 via the fixing device 1 is securely held. The process of bolting a cleat or fitting to the fixing device 1 automatically results in the deformation which causes the various notches and lips to become engaged closer with the first and second members 110, 120 of the mesh. The deformation creates a secure vibration-free fit between the mesh and the fixing device 1 and also allows the fixing device 1 to be fitted to meshes having different wire diameters.

Figure 5 shows a cable cleat 200 attached to a basket tray, having a mesh 100 base, using a fixing device 1 according to any statement herein. Three cables 301, 302, 303 are located and restrained within the cable cleat.

Although a cleat 200 for restraining three cables of a three-phase power supply is illustrated, any object may be attached using the fixing 1. As mentioned previously, when a short circuit occurs in a three-phase power supply large vibrational forces in all directions can occur. As such, a fixing device 1 that attaches a cleat 200 to a basket tray mesh 100 also experiences large vibrational forces in all directions. Due to the structure and assembly of the fixing device 1 and the bolt 200, the fixing device 1 is prevented from any significant movement in any direction.

In other words, the fixing device 1 enables a cleat 200, or other object, to be securely attached to a mesh 100.

The fixing device I may be manufactured from stainless steel. This provides sufficient strength whilst also being resistant to corrosion. The fixing device 1 may be manufactured from a reel of strip steel. With reference to Figure 6 a flat piece of steel is stamped from the strip of steel. The stamping process forms the first part 10 and second part 20 as a single piece. The holes 12, 14, lips 14, 18, 24 and notches 16, 26 are formed during the stamping process. The flat stamped piece of steel is then folded in two operations. In the first operation the first lip 14 and second lip 18 of the first part 10 are folded at right angles to the first part 10 and the second part 20 is folded at right angles to the first part 10. In the second operation the second part 20 is folded by a further 90 degrees so that the second part 20 is substantially parallel to the first part 10. As will be apparent to one skilled in the art, other manufacturing techniques are possible. For example, the fixing device 1 may be made from three discrete parts, a first part 10, second part 20 and a connecting part 30 that may be welded together.

Alternatively, a first part 10 may be directly welded, or otherwise connected, to a second part 20. In other embodiments, the fixing device may be cast as a single piece, or as multiple pieces welded together.

Although the fixing device 1 has been described as being manufactured from stainless steel, other materials may be equally suitable. For example, the fixing device 1 may be manufactured from galvanised steel or aluminium. It is also possible to manufacture the fixing device 1 from plastic. In this case, the fixing device may be manufactured by injection moulding.

The fixing device 1 may be attached to a mesh 100, such as a cable basket tray, in-situ both quickly and easily. This is partly due to the single piece design. No special tools are required in order to attach the fixing device 1 to a mesh. The fixing device 1 allows an object, such as a cable cleat, to be attached to a mesh 100.

Further, due to the configuration of the fixing device 1 a connection that can withstand a large oscillating or static force is formed. The deformation of the fixing device 1 that occurs when an object is fastened to it improves the strength and rigidity of the connection. The fixing device 1 may also be manufactured quickly and cheaply, this is partly due to the single piece design.

Figure 7 illustrates a second embodiment of the fixing device 1. This embodiment is substantially the same as the embodiment illustrated in Figure 1. However, the first part 10 does not have a second lip 18 and there is therefore no notch as such. When in use, the fixing device is prevented from moving to the right (+x) by the bolt 220, and the notch 26 defined by the gap between the lip 24 and the connection 30 of the first part 10 and the second part Figure 8 illustrates a third embodiment of the fixing device 1. This embodiment is similar to the embodiment shown in Figure 1. However, the first part 10 does not have any lips. When in use, the fixing device is prevented from moving to the right (+x) or left (-x) by the bolt 220, and the notch 26 defined by the gap between the lip 24 and the connection 30 of the first part 10 and the second part 20.

Figure 9 illustrates a fourth embodiment of the fixing device 1. This embodiment is similar to the embodiment shown in Figure 1. However, the first part 10 does not have a second lip 18 and the second part 20 does not have a lip 24. When in use, the fixing device is prevented from moving to the left (-x) by the first lip 14 on the first part 10.

Figure 10 illustrates a fifth embodiment of the fixing device. This embodiment is substantially the same as the embodiment shown in Figure 1. However, the notch 16 or the part 10, defined by the gap between the first lip 14 and the second lip 18, is substantially the same width as the first member 110 of the mesh. The edges of the first and second lips 18 of the first part 14 are arranged so as to be in contact, or at least within close proximity, to the first member 110 of the mesh.

In a sixth embodiment of the fixing device 1 the first part 10 and second part 20 are not substantially parallel to each other. Instead, there is a slight angle between them. This angle may be in the region of 5-20°. This allows the fixing device 1 to be attached to a mesh 100 more easily. Whilst the first part 10 and second part 20 need not be parallel, the first hole 12 and the second hole 22 must be substantially concentric inasmuch as a bolt 220 or similar fixing can be passed through them. Upon passing a bolt 220 through the fixing device 1 and tightening it up with a nut 240, the fixing device 1 deforms and the angle between the first part 10 and second part 20 decreases.

Upon further tightening, the first part 10 and second part 20 become slightly concave and tightly grip the mesh 100 to form a secure fixing.

Claims

CLAIMS: 1. A fixing device for facilitating the attachment of an object to a mesh, the mesh having a plurality of first members and a plurality of second members wherein the first members are perpendicular to the second members, the fixing comprising: a first portion (10) having a first hole (12) and a second portion (20) having a second hole (22); wherein: the first portion (10) and the second portion (20) are permanently connected together to form a gap between the first and second portions; the first hole (12) and second hole (22) are substantially concentric so as to allow a bolt to pass through them; at least one of the first and second portions (10, 20) has a lip (14, 24) that extends over a portion of the width cf the said portions; and the lip (14, 24) is arranged to engage with a first member of the mesh to retain the fixing device at an intersection point of the mesh.
2. The fixing device according to claim 1, wherein the gap formed between the two portions (10, 20) is substantially constant.
3. The fixing device according to claim 1 or 2, wherein the first portion (10) and the second portion (20) are in the form of plates.
4. The fixing device according to any preceding claim, wherein the first portion (10) and second portion (20) are integrally formed.
5. The fixing device according to any preceding claim, wherein: the lip comprises a first lip (14) formed on the first portion (10); and the first lip (14) is formed on a side that is opposite from a side that is connected to the second portion (20)
6. The fixing device according to claim 5, wherein: the first portion (10) further comprises a second lip (18) that extends over a portion of the width of the first portion (10); the second lip (18) is formed on the same side of the first portion (10) as the first lip (14); the second lip (18) is spaced apart from the first lip (14) so as to form a notch (16); and the notch (16) is arranged to engage the first member.
7. The fixing device according to any preceding claim, wherein: the lip comprises a lip (24) formed on the second portion (20); and the lip (24) is formed on the same side as the side that is connected to the first portion (10)
8. The fixing device according to claim 7, wherein the lip (24) is arranged to engage a second member in addition to the first member.
9. The fixing device according to claim 7 or 8, wherein: the second portion (20) comprises a notch (26) formed between the lip (24) of the second portion (20) and the connection (30) between the first and second portion; and the notch (26) is arranged to engage the first member.
10. A system for supporting at least one power cable comprising: a cable basket tray comprising a mesh (100) having a plurality of first members (110) and a plurality of second members (120) , wherein the first members are perpendicular to the second members; a fixing device (1) according to any of claims 1- 9, wherein a portion of the mesh (100) is located within the gap between the first portion (10) and the second portion (20) and the lip (14, 24) is engaged with a first member (110) of the mesh; and a cable retaining device (200) retaining the at least one cable, wherein the cable retaining device is attached to the fixing device (1) by a fixing (220, 240) that passes through the first hole (12) of the first portion (10) and the second hole (12) of the second portion (20)
11. A method of supporting at least one power cable, comprising the steps: attaching a fixing device (1) according to any of claims 1-9 to a cable basket tray comprising a mesh (100), the mesh having a plurality of first members (110) and a plurality of second members (120) wherein the first members are perpendicular to the second members, such that a portion of the mesh (100) is located within the gap between the first portion (10) and the second portion (20) and the lip (14, 24) Is engaged with a first member (110) of the mesh (100); attaching a cable retaining device (200) to the fixing device by a fixing (220, 240) that passes through the first hole (12) of the first portion (10) and the second hole (12) of the second portion (20) securing the cable retaining device (200) to the fixing device (1) by tightening the fixing; and securing the at least one cable within the cable retaining device.
12. A fixing device, substantially as described herein with reference to the attached drawings.