AU2006235786A1 - A utility pole joint - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): BLUESCOPE STEEL LIMITED Invention Title: A UTILITY POLE JOINT The following statement is a full description of this invention, including the best method of performing it known to me/us: IND 2 A Utility Pole Joint o Field of the Invention The present invention relates generally to steel utility IND poles and more specifically to improve jointing OO arrangements for connecting sections of a utility pole together.

IND

10 Background of the Invention (Ni Utility poles made from steel are typically formed from tapered hollow sections that are fitted one within the other. These sections are typically 4 to 8 metres in length and have a polygonal cross section. To erect the pole, the sections are lifted and located in place by a crane.

Utility poles are required to accommodate significant design loading because their length. As such, any joint which is incorporated between steel sections of the pole need to have significant load bearing capacity.

Whilst existing designs are adequate, the need to introduce a taper to allow connection of the pole sections substantially increases the costs of forming these sections as compared to simple cylindrical shaped sections. Accordingly to reduce the cost of the pole construction it would be desirable to provide a jointing arrangement that allows the pole sections to be connected end to end with a butt connection thereby enabling the pole sections to be of simpler shape.

IND 3 Summary of the Invention o In a first aspect, the invention relates to a joint connecting first and second hollow sections of a steel utility pole in end to end abutting relation, the utility ND pole having a central axis and the sections having 0 opposite ends spaced along the axis, the joint comprising and expandable insert located within the pole, the insert (N being generally cylindrical and being formed from a plurality of parts that are movable relative to one another to allow for radial expansion of the insert; and fastening means fastening the insert to each of the first and second sections, wherein the insert is connected to an inner surface of the sections so as to allow loading to distributed from the insert to the first and second sections of the utility pole.

In accordance with this aspect of the invention, a joint for a steel utility pole is provided that allows sections of the pole to be connected in end to end relation. As such, these sections of pole do not require a taper to allow nesting of one pole within the other in accordance with the prior art utility poles. As such, the sections of the utility pole can be cylindrical thereby significantly reducing their cost to manufacture.

Further, to accommodate the design loadings required at the pole joint, a radially expandable insert is provided within the joint which is able to transmit loading between the insert and the sections of pole being interconnected.

This has the significant advantage that it allows the joint to accommodate considerably more load than if the joint was required to rely solely on the fasteners to IND 4 carry the load between the insert and the sections of the utility pole.

C.)

0 In one form, the insert is polygonal in cross section perpendicular to the utility pole axis. In one form, each D part is formed as an open section having opposite ends and O0 first and second edges that extend between the ends. In a particular arrangement, these edges are profiled with (N projections and recesses that enable interlocking of the edges of the parts.

In a particular arrangement, the joint further comprises a plurality of bearing plates that are disposed between the insert and the sections and wherein loading is arranged to be distributed between the insert and the sections through the bearing plates.

In an arrangement where the insert is polygonal, in one form, the sections of pole may be other than polygonal (ie. circular or elliptical). In this form, the bearing plates are connected to those sections of the pole and provide a mating surface for the insert.

In a particular embodiment, the bearing plates are rigidly fixed to one of the sections, such as through a welding process, and are arranged to project from that section of the pole so as to be receivable within the other section of the pole. With this arrangement, the bearing plates also assist in assembly of the pole sections.

In a particular form, at least some of the bearing plates extend along the joint between adjacent parts of the insert.

I- 5 In a particular form, the insert is formed from metal, Stypically sheet steel.

In one form, the fastening means comprises a plurality of mechanical fasteners which fasten the sections to the 00 O0 insert. In a particular form, these sections and the insert include preformed holes operative to receive these (N fasteners. In an arrangement where the insert includes projections disposed on the edges of the first and second parts, these preformed holes are arranged on those projections to receive the fasteners.

In a further form, where the bearing plates are utilised in the joint, the mechanical fasteners extend through plates which typically include preformed holes to facilitate receipt of those fasteners.

In a further aspect, the invention is direct to a utility pole having a central axis and comprising a plurality of hollow sections having opposite ends spaced along said axis and being connected in end to end abutting relation.

In accordance with this further aspect, preferably a joint according to any of the forms described above is utilised to interconnect the sections.

In one form, these sections are circular in cross section.

In a particular form, these sections are between 15 to metres in length. In this form, these section lengths are significantly larger than previous pole construction and enable the pole post to be formed in two sections rather I- 6than in the four or five sections as common in the prior art.

C) O In a further aspect, the invention is directed to a method of interconnecting hollow metal sections of a metal utility pole in end to end abutting relation, the method 0O 00 comprising the steps of: locating an insert within the sections; expanding the insert within the sections; and (Ni \O securing the insert to each of the sections in its expanded configuration.

Brief Description of the Drawings It is convenient to hereinafter describe an embodiment of the invention with reference to the accompanying drawings.

The particularity of the drawings and the related description is to be understood as not superseding the generality of the preceding broad description of the invention.

In the drawings: Fig. 1 is a schematic view of a utility pole; Fig. 2 is a detailed view of a joint between sections of the post of the utility pole of Fig. 1; Fig. 3 is an exploded view of the joint of Fig. 2; Fig. 4 is a detailed perspective view of the insert of the joint of Fig. 2.

Fig. 5 is a cross sectional plan view of the joint of fig. 2 before fastening; and Fig. 6 is the cross section view of the joint of Fig. 4 after fastening.

O 7 Detailed Description of the Drawings 0 0 Fig. 1 illustrates a utility pole 10 which incorporates two primary sections, being a post 11 and a cross arm 12.

In the illustrated form, both the post 11 and cross arm 12 00 0 are formed from steel. However, it is to be appreciated that the cross arm could be formed from other materials, most notably timber. INO The post 11 is formed from hollow steel sections. The sections are cylindrical having a circular cross section that is constant along the length of the post 11. The post 11 is formed from two sections (a lower section 13 and an upper section 14) and a joint 15 is provided to connect these sections together in end to end abutting relation.

Figs. 2 to 6 illustrate the joint 15 in more detail. As best illustrated in Fig. 2, the pole sections 13 and 14 form a substantially flush connection at the joint Further, the main components of the joint which provides the necessary strength are located within the post. In the illustrated form, the only parts of the joint 15 which protrude from the outer surface of the sections are the heads of fasteners 16 which are used to secure the various parts together as will be described in more detail below.

This arrangement is beneficial as the generally smooth exterior surface along the joint 15 reduces catch points which would present a hazard to maintenance workers on the pole.

Fig. 3 and 4 illustrates the primary components of the joint 15 in more detail. The joint 15 includes a IND 8 cylindrical insert 17 which is polygonal in cross section.

The insert is formed from first and second parts 18 and 19 o that are typically fabricated from sheet steel. The parts are connected via profiled edge regions (20, 21, 22, 23).

This profiling forms a plurality of interfitting projections 24 and recesses 25. The projections and 00 0O recesses are formed as re-entrants so that the projections of one part of the insert are captured within the recesses N of the other part of the insert. This connection inhibits separation of the parts on the application of a force perpendicular to the edge of the respective parts, but allows lateral movement of the parts relative to each other. This lateral movement allows the insert to expand as will be described in more detail below.

The joint 15 further includes bearing plates 26, 27, 28 and 29 which in the illustrated form are connected within the lower section 13 of the pole typically by a welded connection. As best illustrated in Fig. 3, an upper part of the respective bearing plates (26 29) project from the lower section 13 and provide a guide to location of the insert 17 and the upper section 14 on to the lower section 13.

The bearing plates are formed from flat strip steel. As the inner profile of these pole sections is circular in cross section, these bearing plate interconnect segments of the sections to form a chord across those sections.

This is best illustrated in Figs. 5 and 6. With this arrangement, the bearing plates (26 to 29) provide a mating surface for the polygonal insert 17 with the inner surface of the bearing plates mating against similarly planar surfaces of the insert.

IN 9 As indicated above, fasteners 16 (which in the illustrated o embodiment are in the form of nut 30 and bolt 31 assemblies) are used to secure the various components of the joint 15 in place. To facilitate location of the fasteners, preformed holes 32 are formed in each of the 00 OO sections 12, 13, the insert 17 and in the respective bearing plates, 26, 27 and 28. Further, these preformed (N holes 32 are aligned in a plurality of lines angularly spaced about the pole axis with two of these lines of holes being located along the join between the edge margins (20, 21, 22 and 23) of the insert. With this arrangement, two of the bearing plates 27 and 29 are arranged to align along the respective joints formed between the insert parts 18 and 19.

To allow the fasteners to be installed from outside the sections, the nuts 30 are spot welded onto the inner side of the insert 17 and are aligned with the preformed holes.

In this way the bolts can be inserted from the exterior of the sections to engage with the nuts located in the interior of the joint.

Fig. 5 illustrates the arrangement of the components of the joint 15 prior to fastening. As can be seen, there is some "play" with the components, with the insert being slightly smaller than the spacing defined by the bearing plates (26 -29) This is required to allow easy fitting of the insert and also to accommodate variations in the inner diameter of the pole sections 13, 14.

Fig. 6 illustrates the joint 15 following fastening. As can be seen, on tightening of the fasteners 16, the insert ND 10 parts 18, 19 expand slightly and are drawn into tight engagement with the bearing plates (25, 29) which in turn o bear against inner surface of the sections. This expansion of the insert is accommodated by the insert sections 18, 19 being able to move relative to one another, thereby enabling the individual sections to 00 deform more readily as compared to if the sections were formed from a single piece. By forming this intimate contact between the joint components, bending is able to be accommodated by the interaction between the insert, bearing plates and the sections and is not accommodated solely by the bolts 31 of the fasteners assemblies. This substantially increases the strength of the joint 15 in bending and enables the joint strength to be consistent with the remainder of the pole.

Furthermore, the joint components, particularly the insert 17, is relatively light weight so that the can be manually lifted into place. This not only comes about because the insert is provided in sections but also because the sheet metal from which the insert sections are formed can be thinner because of the bearing plates provide an increase in effective thickness at areas of high stress in the joint.

In use, the post 11 can be erected simply and quickly.

Typically the lower section 13 is secured in place. The upper post section 14 is then lifted by a crane over the top of the lower section. A worker is then positioned at the top of the first section and installs the insert onto the lower section 13 and then guides the upper section over the insert and bearing plates and then fastens the upper section 14 to the insert. The fasteners are then D- 11 O all tightened to a required torque level (sufficient to ensure that the insert is drawn into engagement with the o bearing plates) and assembly of the pole post 11 is complete. The cross arm assembly 12 is then able to be installed.

IO

00 In the claims which follow and in the preceding Sdescription of the invention, except where the context (Ni requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Variations and/or modifications may be made to the parts previously described without departing from the spirit or ambit of the invention.

Claims (10)

1. 2. A joint according to claim 1, wherein the insert is polygonal in cross section perpendicular to the utility pole axis.
2. 3. A joint according to either claim 1 or 2, wherein each of the inserts is formed as an open section having opposite ends and first and second edges that extend between the ends, the edges being profiled with projections and recesses that enable interlocking of the edges of the parts.
3. 4. A joint according to any preceding claim, further comprising a plurality of bearing plates that are disposed between the insert and the sections, and wherein loading is arranged to be distributed between the insert and the sections through the bearing plates. A joint according to claim 4, wherein the bearing plates are rigidly fixed to one of the sections and are arranged to project from that section of the pole so as to be receivable within the other section of the pole. ND 13 \O
4. 6. A joint according to either claim 4 or 5, wherein respective ones of the bearing plates extend along the O joint between adjacent parts of the insert. M 5 7. A joint according to any preceding claim, wherein the fastening means comprises a plurality of mechanical IND fasteners which interconnect the sections to the insert. 00 M8. A joint according to claim 7, wherein the sections (N ND 10 and the insert include preformed holes arranged to receive the fasteners.
5. 9. A joint according to claim 8, wherein the insert includes projections disposed on the edges of the first and second parts, and the preformed holes are arranged on those projections to receive the fasteners. A utility pole having a central axis and comprising a plurality of hollow sections having opposite ends spaced along said axis and being connected in end to end abutting relation.
6. 11. A utility pole according to claim 10, wherein the hollow sections are interconnected by a joint according to any one of claims 1 to 9.
7. 12. A utility pole according to either claim 10 or 11, wherein the sections are circular in cross section.
8. 13. A utility pole according to any one of claims 10 to 12, wherein the sections are between 15 to 25 metres in length. ND 14 \O
9. 14. A method of interconnecting hollow metal sections of a metal utility pole in end to end abutting relation, the 0 O method comprising the steps of: locating an insert within the sections; expanding the insert within the sections; and securing the insert to each of the sections in its expanded configuration. \O 00 A joint substantially as herein described with Sreference to the accompanying drawings. ND
10. 16. A utility pole substantially as herein described with c' reference to the accompanying drawings.