NZ337234A - Cable tray with a central spine carrying a series of parallel rungs, the outer end portion of each rung bent upwardly to a relatively small radius - Google Patents

Abstract

The specification describes a cable tray. The tray has a central spine (10) carrying a series of parallel rungs (2).

Description

P:\0PER\RSH\CABLE3.CAP- 11/8/99 - la -CABLE SUPPORT SYSTEM The present invention relates to cable support systems and more particularly to so-called cable trays or cable ladders, hereinafter referred to, simply, as cable trays.

One form of cable tray system currently available utilises a cable tray comprising a central longitudinal spine and cable-receiving portions at opposite sides of the spine. The central spine carries supporting rods by which the tray is supported from a ceiling or other overhead support structure. This form of cable tray can provide easier installation for the tray 10 itself and also easier installation of the cables within the tray than is possible with a conventional cable tray in which the support rods are attached to the opposite longitudinal sides of the tray.

Hitherto, a cable tray of the type discussed above has been fabricated using a tube of 15 rectangular cross-section as the central spine with the cable-supporting portions at opposite sides of the spine being formed by a series of parallel rungs consisting of tubes which extend transversely through the central spine and extend to each side of the spine. Each end portion of the rung is bent upwardly so that, in use, cable within the cable-receiving portion of the tray is confined at the lateral outer side by the upwardly bent portions of the rungs. A cable 20 tray of this general type is disclosed in our International patent application No.PCT/AU97/00788 to which reference may be made.

In the manufacture of these cable trays using high speed manufacturing processes, difficulties arise in satisfactorily bending the end portions of the rungs to a tight radius, 25 particularly when using a relatively thin walled tube as there is a tendency for the tube to collapse and crease in an uncontrolled manner during bending and this can result in an unattractive appearance which is unacceptable commercially. To overcome the difficulties in obtaining a smooth bend for the end portions of the rung section, resort has been made to the use of a greater wall thickness for the rung section than is necessary having regard to the 30 structural requirements of the tray and this, in turn, adds to the overall cost of the tray.

P:\0PER\RSH\CABLE3.CAP-11/8/99 According to one aspect of the present invention, there is provided a cable tray comprising a central spine carrying a series of substantially parallel rungs projecting to opposite sides of the spine to define cable-receiving portions, wherein each rung is of a cross-section which reinforces the rung against deflection under the weight of the cable carried, and 5 at least one outer end portion of at least some of the rungs is bent upwardly to define an upstanding end portion which confines the cable laterally, there being a plurality of such upstanding end portions at each side of the spine, and wherein each upstanding end portion is bent to a relatively small radius facilitated by modifying the cross-section of the rung at that end portion.

According to another aspect of the invention, there is provided a cable tray comprising a central spine carrying a series of substantially parallel rungs projecting to opposite sides of the spine to define cable-receiving portions, wherein each rung is of a cross-section which reinforces the rung against deflection under the weight of the cable carried, and the outer end 15 portions of the rungs are bent upwardly to define upstanding end portions which confine the cable laterally, wherein at each outer end portion the cross-section of the rung is modified to facilitate bending thereof to a relatively small radius.

Advantageously, the modification in the cross-section of the outer end portions of the 20 rungs results in a cross-section which is elongate in the width direction in relation to the depth direction.

In one preferred form, the rungs are of tubular section and the outer end portions of the rungs are modified by substantially flattening the tubular section at the end portion. 25 Preferably, the tubular section is rectangular, although other tubular section such as circular could be used.

In another preferred form, the rungs are formed from a channel section or C-section, and the cross-section of the outer end portions of the rungs is modified by substantially 30 flattening the section at the end portions. Preferably, flattening takes place by inwards folding of the side walls of the section.

P:\0PER\RSH\CABLE3.CAP- 11/8/99 In another form, the rungs are formed from a channel section or C-section, and the cross-section at the outer end portions is modified by removal of the side walls of the section.

Embodiments of the invention will now be described, by way of example only, with 5 reference to the accompanying drawings, in which: Figure 1 is a side view of part of a rung formed in accordance with a first embodiment of the invention in which the rung is a tube of rectangular cross-section flattened at each end portion; Figure 2 is a plan view corresponding to Figure 1; Figure 3 is an end view corresponding to Figure 1; Figure 4 is a section on line A-A of Figure 1; Figure 5 is a perspective view showing the end portion of the rung of Figure 1; Figure 6 is an underneath perspective view corresponding to Figure 5; Figures 7 is a perspective view showing part of a cable tray having rungs as shown in 15 Figures 1 to 6; Figure 8 is a side view showing part of a rung formed from a tube of rectangular cross-section and flattened at its end portion in a different manner to that of Figures 1 to 7; Figure 9 is a plan view corresponding to Figure 8; Figure 10 is an end view corresponding to Figure 8; Figure 11 is a section taken on line A-A of Figure 8; Figure 12 is a perspective view of the end portion of the rung of Figure 8; Figure 13 is an underneath perspective view showing the rung of Figure 8; Figure 14 is a side view showing a part of a rung formed from a C-section or channel section of which the end portion is formed by flattening the section; Figure 15 is a plan view corresponding to Figure 14; Figure 16 is an end view corresponding to Figure 14; Figure 17 is a section taken on line A-A of Figure 14; Figure 18 is a perspective view showing the end portion of the rung of Figure 14; Figure 19 is an underneath perspective view showing the end portion of the rung of 30 Figure 14; Figure 20 is a side view showing part of a rung formed from a C-section or channel P:\0PER\RSH\CABLE3.CAP-11/8/99 section with side walls of the section cut away to form the end portion of the rung; Figure 21 is a plan view corresponding to Figure 20; Figure 22 is an end view corresponding to Figure 20; Figure 23 is a section on line A-A of Figure 20; Figure 24 is a perspective view showing the end portion of the rung of Figure 20; and Figure 25 is an underneath perspective view showing the end portion of the rung of Figure 20.

In each of the preferred embodiments now to be discussed there is disclosed a metal rung construction for a cable tray of the type discussed above which enables the end portions 10 of the rung to be bent upwardly with a smooth bend to a very small or tight radius while using a relatively thin-walled section for the rung, typically a wall thickness of 0.9mm or less.

In Figures 1 to 6 the rung 2 is formed from a tube 4 of rectangular cross-section which is flattened at each end portion 6 with a concertina-type fold whereby the width of the 15 flattened end portion 6 is the same as that of the remainder of the rung, but the depth of the end portion 6 is considerably reduced to the extent that the inwardly folded layers 6a which result from flattening the end portion in this way are substantially in contact with each other and with the two outer layers to reduce the depth dimension to a minimum. Accordingly the cross-section of the end portion 6 is elongate in the width direction of the end portion 6 and 20 a smooth, tight, bending radius can be achieved for the upstanding end portion 6 of the rung and which laterally confines the cable within the cable tray. A length of completed cable tray with rungs 2 formed in this manner is shown in Figure 7. In this figure, the central tubular spine of the cable tray is designated 10.

Apart from achieving the significant advantage of enabling high speed formation of the bent end portions 6 of the rungs while using a thin-walled rung section, the flattening of each end portion 6 also closes the end portion against ingress of water thereby avoiding the need to apply closure caps to the upstanding upper ends of the rungs.

In Figures 8 to 13 the end portions 6 of the rung 2 are flattened to provide a two-layer construction (in contrast to the four-layer construction of the previous embodiment). This P:\0PER\RSH\CABLE3.CAP- 11/8/99 results in an outwards flow of the material which increases the width of the end portion 6 in relation to the width of the remainder of the rung section and significantly reduces its depth to a depth substantially equivalent to twice the wall thickness so that, in cross-section, the end portion of the rung is elongate in the width direction with the width dimension being many 5 times greater than the depth direction. In this embodiment, advantageously the flattening is carried out in such a way that the increased width of the flattened end portion 6 is substantially constant over a length which corresponds to or is greater than the height of the bent end portion so that this will appear of constant width in the completed rung. This flattened portion of constant width is joined to the rectangular cross-section of the main body 10 of the rung by a transition portion 12 of progressively reducing width and increasing thickness.

In Figures 14 to 19 the rung 2 is formed of a C-section or channel section 14 rather than of a square section tube, with the section 14 being open at the bottom in the completed 15 rung. The end portions 6 of the rung are flattened by folding the side walls of the section 14 inwardly as shown, so that the width of the flattened end portion 6 is the same as that of the remainder of the rung, but its depth is reduced to substantially twice the wall thickness of the section. Accordingly, in cross-section, the flattened end portion is elongate in the width direction. This folding of the side walls of the section 14 to form the flattened end portion 20 6 creates a transition section 16 formed by progressive bending of the side walls adjacent the end of the horizontal part of the rung.

In Figures 20 to 25 the rung is again formed from C-section or channel section 14, but in this embodiment the side walls of the section are cut away at each end portion 6 of the rung 25 so that the end portion 6 is formed only by the upper wall of the section 14 and therefore is of single layer construction which can easily be bent upwardly.

Although in the preferred embodiments of the invention each end portion of each rung is bent upwardly to a very small or tight radius to define upstanding end portions which 30 confine cable laterally, in alternative embodiments the upstanding end portions are not provided on every rung although it will be appreciated that it is important for there to be a P:\0PER\RSH\CABLE3.CAP • 11/8/99 sufficient number of rungs with upstanding end portions along a length of cable tray to provide adequate lateral confinement for the cables. In this form of embodiment, some rungs may be devoid of upstanding end portions at both ends or may alternatively be provided with an upstanding end portion at one end only with the rungs being orientated in such a manner 5 that at each side of the central spine there are sufficient numbers of upstanding end portions to ensure proper lateral confinement of the cables carried by the tray.

Throughout this specification and claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will 10 be understood to imply the inclusion of a stated integer or group of integers or steps but not the exclusion of any other integer or group of integers.

The embodiments have been described by way of example only and modifications are possible within the scope of the invention.

P:\0PER\RSH\CABLE3.CAP -11/8/99

Claims (10)

CLAIMS:- /V 7

1. A cable tray comprising a central spine carrying a series of substantially parallel rungs ~2- projecting to opposite sides of the spine to define cable-receiving portions, wherein each rung 5 is of a cross-section which reinforces the rung against deflection under the weight of the cable J? carried, and at least one outer end portion of at least some of the rungs is bent upwardly to define an upstanding end portion which confines the cable laterally, there being a plurality of such upstanding end portions at each side of the spine, and wherein each upstanding end portion is bent to a relatively small radius facilitated by modifying the cross-section of the 10 rung at that end portion. __ f_! / /o *

2. A cable tray comprising a central spine carrying a series of substantially parallel rungs projecting to opposite sides of the spine to define cable-receiving portions, wherein each rung is of a cross-section which reinforces the rung against deflection under the weight of the cable 15 carried, and the outer end portions of the rungs are bent upwardly to define upstanding end portions which confine the cable laterally, wherein at each outer end portion the cross-section of the rung is modified to facilitate bending thereof to a relatively small radius.

3. A cable tray according to claim 1 or claim 2, wherein the modification in the cross-20 section of the outer end portions of the rungs results in a cross-section which is elongate in the width direction in relation to the depth direction.

4. A cable tray according to any one of claims 1 to 3, wherein the rungs are of tubular section and the outer end portions of the rungs are modified by substantially flattening the 25 tubular section at that end portion.

5. A cable tray according to claim 4, wherein the tubular section is rectangular and flattening occurs by inwards folding of one pair of opposed side walls of the section. 30 6. A cable tray according to claim 4, wherein flattening occurs by outwards displacement of the material forming the tubular section. m

P:\0PER\RSH\CABLE3.CAP- 11/8/99 3 3 7 2 3 4 -8-

7. A cable tray according to any one of claims 1 to 3, wherein the rungs are formed from a channel section or C-section, and the cross-section of the outer end portions of the rungs is modified by substantially flattening the section at the end portions. 5

8. A cable tray according to claim 7, wherein flattening takes place by inwards folding of the side walls of the section at the end portion.

9. A cable tray according to any one of claims 1 to 3, wherein the rungs are formed from a channel section or C-section, and the cross-section of the outer end portions of the rungs is 10 modified by removal of the side walls of the section.

10. A cable tray substantially as hereinbefore described with reference to the accompanying drawings. DATED this 11 day of August, 199 9 RAMSET FASTENERS (AUST.) PTY. LIMITED By its Patent Attorneys: DAVIES COLLISON CAVE