GB2205005A

GB2205005A - Assembling plasters trunking from elongate strips

Info

Publication number: GB2205005A
Application number: GB08809812A
Authority: GB
Inventors: Frank Harold Ferguson
Original assignee: Grawater Ltd
Current assignee: Grawater Ltd
Priority date: 1987-04-30
Filing date: 1988-04-26
Publication date: 1988-11-23
Anticipated expiration: 2008-04-26
Also published as: AU1527488A; GB8710311D0; NZ224416A; AU597486B2; GB2205005B; GB8809812D0

Abstract

Trunking of various cross-sectional shapes may be assembled from elongate sections of substantially flat plastics material by folding along longitudinal channels 14,15,20 provided therein and fastening a lid portion 20 by clips 23,24. The lid may be separate from the aforementioned elongate sections and secured by other means eg adhesive tape. The elongate sections of plastics material may be supplied coiled in the substantially flat (i.e. unassembled) condition the material having "memory" for straightening after unrolling. Suitable materials are disclosed. <IMAGE>

Description

PLASTICS TRUNKING The present invention relates to trunking made from plastics material e.g. P.V.C.

Trunking is used generally in the electrical industry to contain electric wires and cables.

Traditionally, the trunking is made of a relatively rigid plastics material in discrete lengths of 1 or 2 meters. The trunking is usually of U-shaped cross section so that it can be affixed to a wall or ceiling by means of nails or screws through the base of the U and after the wires or cables are inserted in the U an elongate cover strip is snapped on to form a closed box.

This arrangement has the disadvantage that there is considerable waste when installing the trunking since short sections usually have to be cut from the standard discrete lengths.

The present invention has an object to provide plastics trunking in a form such that it can be substantially continuous whereby to reduce waste. This is best achieved by forming the trunking as a coil which also reduces storage space and eases handling.

In order that the present invention be more readily understood an embodiment thereof will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 shows a cross-sectional view of a generally flat elongate extrusion of plastics material to form trunking according to an embodiment of the present invention; Fig. 2 shows a cross-sectional view of the partially assembled trunking according to the embodiment of Fig. 1; and Fig. 3 shows a cross-sectional view of assembled trunking according to the embodiment of Fig.

1.

The embodiment shown in the drawings is based on the use of a substantially flat elongate extrusion of plastics material (see Fig. 1) which is capable of being folded longitudinally (see Fig. 2) to form trunking of generally square cross-section (see Fig. 3). The trunking of this embodiment has an integral elongate lid portion. The size and cross-sectional shape of the trunking can be altered from that shown in the drawings so as to form polygonal, e.g. hexagonal, cross-sections by varying the relative sizes of, and angles between, portions of the elongate extrusion. Also the lid portion of the trunking need not be integral with the body of the trunking but may be formed as a separate extrusion.

Turning now to Fig. 1, this shows a substantially flat elongate extrusion of plastics material according to the present invention provided with longitudinal channels enabling the extrusion to be folded longitudinally to form trunking.

The extrusion/trunking comprises a base portion 10 provided with side wall portions 11 and 12 which are integrally hinged to the base portion 10 along the edges 14 and 15 (the longitudinal V channels define the edges of the various portions of extrusion/trunking). In the illustrated embodiment the extrusion/trunking is provided with bracing male and female interconnection means, in the form of stays 16 and 17 which engage with grooves 18 and 19, to enable the side wall portions 11 and 12 to be retained in an angled position relative to the base portion 10 (see Fig. 2).

Other embodiments of the invention may use different means for retaining the side walls in position relative to the base portion on assembly of the trunking. For example, male and female parts may be provided on the opposing faces of the longitudinal V channels 14 and 15, or some means external to the plastics extrusion itself may be used. Also, it should be understood that embodiments of the invention may dispense with the bracing male and female interconnection means altogether and rely instead on the angles -of the longitudinal V channels, and the provision of a lid portion connecting the "free" edges of the side wall portions, to retain the side wall portions in the appropriate positions when the trunking is in an assembled condition.

As mentioned above, in the embodiment shown a lid portion is also provided hinged to the side wall portion 11 along edge 21. In this embodiment male and female grip fits 23, 24 are provided on the extrusion/trunking to enable the lid portion 20 to be retained at the side wall portion 12 to form trunking of square cross-section (see Fig. 3).

Alternative means may be provided to interconnect the lid portion to the body portion of trunking according to the invention. For example, appropriate interconnection means may be provided only on the lid portion, or only on the relevant side wall portion. Equally it would be possible to use trunking that lacks such interconnection means and the lid portion could be secured using some external means, such as adhesive tape.

The various interconnection means and longitudinal channels may be simply extruded into the trunking, which can be formed in any convenient thickness. The extruded section may be formed with fixing screw holes therein or plain, as shown, or may have an adhesive backing.

The extrusion is preferably of polyvinylchoride (P.V.C.) which is semi-rigid with a "memory" for remembering shape. The extrusion can be coiled when it is not longitudinally folded (ie when it is in a substantially flat condition).

The material is advantageously stable at temperatures below 0 C and is resistant to shattering.

A suitable material is commercially available from Plycol (PVC) Limited under the grade reference FC 15/85T and has the following approximate properties. A Cold Flex temperature of -30C, a Cold Bend temperature of -250C and a Tensile Strength of 15.3 MN/m2.

A further suitable material is available from Norsk Hydro Polymers Limited under the grade reference XN 75467 and has the following approximate properties.

A maximum Cold Flex temperature of -6 C, a maximum Cold Bend temperature of -20 C, a minimum Tensile Strength of 15.2 MN/m2 and a nominal Shore A Hardness of 92.

In practice a coil of trunking according to the invention may be formed by producing the appropriate extruded section, cooling the extrusion by a suitable method (e.g. water, air or refrigeration), feeding the extrusion into a set of nip rollers, and winding it into a coil.

When a section of the trunking is required a suitable length may be unrolled from the coil, cut off, and straightened (due to the "memory" of the material).

If the trunking in question is to be of square crosssection a basic U-shape can be formed, by longitudinal folding, and then be affixed to the wall or ceiling as required with the open side facing outward to receive e.g. electrical wires or cables. The lid portion (either integral with the U-shaped section or a separate extrusion) would finally be affixed to complete the square cross-section of the trunking.

Claims

1. Plastics trunking, comprising: a substantially flat elongate member of plastics material having a plurality of longitudinal foldlines defining a plurality of elongate sections, the elongate sections including a median section and at least two wall sections; and means for retaining the wall sections angled relative to the median section when the trunking is in an assembled condition.

2. Plastics trunking according to claim 1 wherein the median and wall sections of the elongate member are adapted to form a channel when the trunking is in an assembled condition, the elongate member includes a further foldline defining a lid section, and there is further provided closure means for retaining the lid section across the elongate opening of the channel when the trunking is in an assembled condition.

3. Plastics trunking according to claim 1, wherein the median and wall sections of the elongate member are adapted to form a channel when the trunking is in an assembled condition; and there is further provided a separate lid member and closure means for retaining the lid member across the elongate opening of the channel when the trunking is in an assembled condition.

4. Plastics trunking according to claim 2 or 3, wherein the retaining means is constituted by the closure means.

5. Plastics trunking according to claim 1, 2 or 3, wherein the retaining means is provided on the elongate member.

6. Plastics trunking according to claim 5, wherein the retaining means comprises complementary parts provided on adjacent elongate sections of the elongate member adapted to interconnect when the trunking is in an assembled condition.

7. Plastics trunking according to any previous claim, wherein the elongate member is of Polyvinylchloride and is coilable.