GB2074213A

GB2074213A - Poles and posts

Info

Publication number: GB2074213A
Application number: GB8112055A
Authority: GB
Original assignee: Hepworth Plastics Ltd
Current assignee: Hepworth Plastics Ltd
Priority date: 1980-04-17
Filing date: 1981-04-16
Publication date: 1981-10-28
Also published as: GB2074213B

Abstract

A pole or post which has low mass, low maintenance costs, high resistance to corrosion and weathering, has a hollow interior, can be made any external colour, and can be made electrically insulated or conducting comprises a tubular member having an outer skin (1) of fibre reinforced synthetic resin, a matrix (2) of synthetic resin and filler in which are embedded longitudinally extending steel elements (3), and an inner skin (4) of fibre reinforced synthetic resin. <IMAGE>

Description

SPECIFICATION Poles and posts This invention relates to poles and posts such as telephone and electricity supply poles, lamp standards, traffic sign posts, flag poles and Rugby football goal posts.

The object of the invention is to provide a construction for a pole or post which has low mass, low maintenance costs, high resistance to corrosion and weathering, has a hollow interior, can be made any external colour, and can be made electrically insulated or conducting.

According to the present invention, a pole or post comprises a tubular member having an outer skin of fibre reinforced synthetic resin, a matrix of synthetic resin and filler in which are embedded longitudinally extending steel elements, and an inner skin of fibre reinforced synthetic resin.

The inner and outer skins may be formed of a fibrous veil and/or mat of relatively low fibre bulk volume fraction impregnated with a synthetic resin. Glass fibre may be used with a polyester resin, but other suitable materials include epoxide, furane, vinyl ester, phenolic, polyimide, silicone, polyurethane resins, and fibres formed from ceramics, silica, asbestos, polyester, polyamide, cotton, jute, aramids, and carbon. It is not necessary for the inner and outer skins to be made from the same materials, but the materials for the outer skin are preferably selected for their ability to withstand ultra violet light and general weather conditions, preferably plus a suitability to incorporation of colour pigment uniformly distributed.

The matrix material may be polyester resin mixed with chopped glass fibres and calcium carbonate, but other suitable materials are as stated for the inner and outer skins and/or particulate materials, such as slate, kaolin, silica, talc, alumina, mica, fly ash, glass flakes and microspheres.

The steel elements embedded in the matrix may be mild steel, of circular or other crosssection, but carbon and stainless steels (of any cross-section) may be used, and the surface of the steel may be treated to enhance the bond between the steel and matrix, and possibly to protect the steel against weathering, such treatment including galvanising, electro-plating, phosphating, polymer coating, etching and mechanical roughening.

The tubular member is preferably formed inside a female mould, in order to give a smooth outside finish (however, it is also possible to produce a smooth interior using a male mandrel), the steel elements are fastened to a fibre mat used in forming the outer skin (as by means of doublesided adhesive tape, over-sewing, pockets on the mat, or clips), the fibre mat is rolled round a carrier tube with the steel elements in contact therewith, the carrier is inserted into the mould which is then rotated to cause the fibre mat to unwind and lie against the mould, the carrier is removed, the mixed matrix material is distributed inside the mould whilst it is rotated, resin from the mix penetrating the fibre mat to complete the outer skin, and whilst still "green", the fibre mat of the inner skin is placed inside the mould in a roll and allowed to unwind uniformly, resin is distributed inside the mould, and the whole tubular member allowed to cure before removal.

The mould may be tapered (so as to form a tapering pole or post), the steel elements being fastened to the fibre mat of the outer skin in a converging array.

Typical dimensions for a telephone pole are:~ Length 8.5 m Inside diameter at base 235 m/m Inside diameter at top 1 10 m/m Diameter of steel elements 3 m/m Thickness of outer skin 1 m/m Thickness of matrix 4 m/m Thickness of inner skin 1 m/m The mould is rotated at 1000 r.p.m., and the carrier tube for the fibre mat and steel element is 50 m/m in diameter.

The steel elements may alternatively be introduced into the fame mould (or on to a male mandrel) as a rigid pre-formed tubular cage, which may be constructed using internal or external circumferential support such as hoops or rings, or a helix, welded, brazed, soldered, bonded, bound, or clipped to the steel elements, and hoops or rings may be in a complete circle or may be gapped to allow slight opening as the steel elements move into contact with the outer skin in the mould (or for closing on to the inner skin on a male mandrel).

A tubular pole or post section in accordance with the present invention and methods of making it will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a fragmentary perspective view showing a tubular pole or post section in accordance with the present invention; Figures 2 to 5 inclusive are fragmentary perspective views showing steel elements fastened in various ways to a fibre mat used in forming the outer skin of the pole or post section shown in Figure 1; Figures 6 to 10 inclusive are diagrammatic fragmentary perspective views showing stages in the formation of the pole or post section of Figure 1 in a female mould using steel elements fastened to a fibre mat as in any of the ways shown in Figures 2 to 5; and Figure 11 is a fragmentary perspective view showing a number of ways of preparing the steel elements as a rigid pre-formed tubular cage for introduction into a female mould (or on to a male mandrel).

In Figure 1 a tubular pole or post section has an outer skin 1 of fibre reinforced synthetic resin, a matrix 2 of synthetic resin and filler in which are embedded longitudinally extending steel elements 3, and an inner skin 4 of fibre reinforced synthetic resin.

In Figures 2 to 5 inclusive the steel elements 3 are shown fastened to a fibre mat IX used in forming the outer skin 1, as by means of doublesided adhesive tape 5 (Figure 2), or over-sewing 6 (Figure 3) or pockets 7 on the mat IX (Figure 4), or clips 8 (Figure 5). In Figure 6 the fibre mat IX with the steel elements 3 fastened thereto is rolled round a carrier tube 9 with the steel elements in contact therewith. The carrier 9 is inserted into a female mould 10 (Figure 7) which is then rotated to cause the fibre mat IX to unwind and lie against the inside of the mould (Figure 8).The carrier 9 is removed from the mould and whilst it is rotated the mixed matrix material 2 is distributed inside the mould (Figure 9), resin from the-mix penetrating the fibre mat IX to complete the outer skin 1, and whilst still "green", the fibre mat 4X of the inner skin 4 is placed inside the mould in a roll (Figure 10) and allowed to unwind uniformly, resin is distributed inside the mould (not shown but effected in similar manner to distribution of the mixed matrix material 2 as in Figure 9), and the whole tubular member allowed to cure before removal of the mould (which though not shown is split for this purpose).

The steel elements 3 may alternatively be introduced into the female mould 10 (or on to a male mandrel) as a rigid pre-formed tubular cage 11 (as shown in Figure 11), which may be constructed using internal or external hoops or rings 12 or 13 respectively, welded, brazed, soldered or bonded to the steel elements, or using spring clips as shown at 14 or pocketed bands as shown at 15, or as otherwise described previously herein.

Claims

1. A pole or post comprising a tubular member having an outer skin of fibre reinforced synthetic resin, a matrix of synthetic resin and filler in which are embedded longitudinally extending steel elements, and an inner skin of fibre reinforced synthetic resin.

2. A pole or post as in Claim 1, wherein the inner and outer skins are formed of a fibrous veil and/or mat of relatively low fibre bulk volume fraction impregnated with a synthetic resin.

3. A pole or post as in Claim 1 or Claim 2, wherein the inner and outer skins are formed of glass fibre and a polyester resin.

4. A pole or post as in Claim 1 or Claim 2, wherein the materials for the outer skin are selected for their ability to withstand ultra violet light and general weather conditions.

5. A pole or post as in Claim 4, wherein the materials for the outer skin are suitable for incorporation of colour pigment uniformly distributed.

6. A pole or post as in any one of the preceding Claims, wherein the matrix material is polyester resin mixed with chopped glass fibres and calcium carbonate.

7. A pole or post as in any one of the preceding Claims, wherein the steel elements embedded in the matrix are mild steel.

8. A pole or post as in Claim 7, wherein the surface of the steel is treated to enhance the bond between the steel and matrix and/or to protect the steel against weathering.

9. A pole or post as in any one of the preceding Claims, wherein the tubular member is formed inside a female mould, the steel elements are fastened to a fibre mat used in forming the outer skin, the fibre mat is rolled round a carrier tube with the steel elements in contact therewith, the carrier is inserted into the mould which is then rotated to cause the fibre mat to unwind and lie against the mould, the carrier is removed, the mixed matrix# material is distributed inside the mould whilst it is rotated, resin from the mix penetrating the fibre mat to complete the outer skin, and whilst still "green", the fibre mat of the inner skin is placed inside the mould in a roll and allowed to unwind uniformly, resin is distributed inside the mould, and the whole tubular member allowed to cure before removal.

10. A pole or post as in Claim 9, wherein the mould is tapered, the steel elements being fastened to the fibre mat of the outer skin in a converging array.

1 1. A pole or post as in any one of Claims 1 to 8, wherein the tubular member is formed inside a female mould or on a male mandrel, and the steel elements are introduced into the female mould or on to a male mandrel as a rigid pre-formed tubular cage.

12. A pole or post comprising a tubular member having a section substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.

13. A method of forming a pole or post substantially as hereinbefore described with reference to Figures 1 and Figures 6 to 1.0 and any one of Figures 2 to 5 of the accompanying drawings.

14. A method of forming a pole or post substantially as hereinbefore described with reference to Figures 1 and 11 of the accompanying drawings.