MODULAR FIBER REINFORCED PLASTIC POLES
Modular fiber reinforced plastic (FRP) poles, suitable for distribution of electricity, telecommunications, lighting and all the other uses relevant to the poles, consisting of successive concave parts of constant cross section (tubes) of various shapes, corresponding annular joints and cap, which are joined together adhesively or/and mechanically. Production method of the poles of the invention, consisting of the assembly of the individual parts, which can be produced industrially in a cost effective manner by the methods of pultrusion (concave parts—tubes) and compression molding (annular joints and cap). Use of the poles of the invention, which can be provided either fully assembled or as a modular product into separate individual parts, packaged in such a way in order to save storage and transportation space and accompanied by the necessary materials, tools and manuals for their assembly and installation on-site.
The invention relates to poles made from reinforced polymers (Fiber Reinforced Plastics—FRP), the production process of poles and the use of poles as a modular product.
Reinforced polymers belong to the class of composites, and consist of polymers and reinforcing glass fibers or other materials (aramid, carbon, etc.) in various forms (yarns, matts, felts, fabrics, meshes).
The poles are widely used for overhead power distribution lines, for the support of transmission lines in telecommunications and for various public and private uses (lighting, road signs, camera support, flag poles, etc.).
The first applications of overhead utility lines, lighting, telecommunications, etc., were made using wooden poles, because it was easier and cheaper to be produced from tree felling. They also had the advantage of insulation. For this reason, they were the dominant technology and even today they still hold the largest share of installed poles in many countries around the world.
Wooden poles, however, have considerable disadvantages due to the nature of wood (natural product), such as being attacked by insects, microorganisms and the weather conditions. Therefore, they require impregnation with dangerous pesticides, the use of which is subject to restrictions (e.g. creosote—DIRECTIVES 98/8/EC, 2011/71/EU). Wooden poles can also spread the fire, and when used in power distribution significant current leakages to the ground occur and reduce the network efficiency. Finally it is a non-industrial product with seasonal production which is not always predictable, with negative consequences on the availability (need to keep large stocks) and the price.
For these reasons, alternative pole technologies and materials have been developed such as iron, reinforced concrete and reinforced polymer (FRP).
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- Iron provides higher strength than wood. Iron poles have stable availability and are hollow, facilitating the passage (lowering) of the cables. However they rust and thus require protection. Furthermore iron is a good conductor of electricity and its use requires additional components (e.g. insulators) and special working conditions and precautions in order to avoid accidents.
- Reinforced concrete provides sufficient strength and a certain degree of insulation, but the heavy weight of these poles is a problem for their transport and installation. Also the rigid behavior of the centrifugal concrete poles in car crushes is dangerous (causing serious traffic accidents). Furthermore, concrete cracks over time and the steel reinforcement is exposed and rusts.
- Poles made of FRP combine significant advantages such as low weight, concave shape, resistance against micro-organisms and environmental conditions and reliable availability. However, their use is limited because of their higher cost, compared to other solutions.
Also in all the above cases (wood, iron, concrete, FRP) the currently existing poles are manufactured, sold, delivered, transported and installed in their full dimension. This means that the user doesn't have the potential to purchase and have these poles delivered as individual parts (modular product) in smaller packaging, and to assemble those on-site (at the installation area), which would facilitate both their transport—by using a smaller transport mean—and their installation, making them cheaper.
Known from the state of the art is document WO00/36251 A1 (Orlandi Mauro), presenting poles capable of supporting overhead electrical or telephone lines, lighting equipment or others from reinforced plastic. The poles consist of portions with dimensions that one end of a portion can be inserted into the end of an adjacent portion. One of the major issues raised in the above mentioned case is that the concave parts have to be of the same shape in order to fit with each other. Moreover, the poles are not constructed entirely of fiber reinforced plastic, which creates the need to maintain the poles and raises the relevant cost. Also known are documents U.S. Pat. No. 8,474,221 B1 (Ceko Peter) presenting a telescoping fiberglass utility pole consisting of three sections protruding and intruding to each other and WO2005/067544 A2 (Composite Tech Corp) presenting a composite utility pole with implements for use in electrical distribution networks.
The present invention relates to poles made of FRP, which consist of individual parts of suitable shape so that:
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- a. every single individual part can be produced in industrialized, automatic or semi-automatic, economical production methods of FRP and
- b. the poles can be easily assembled, in a standardized manner by unqualified personnel by using simple and light tools, according to the manual.
The result of the above design is that the poles of the Invention:
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- a. firstly, have stable and repeatable (industrial) quality, short production cycle and easy availability, combined with low production costs, directly competitive against the poles from other materials, and even lower life cycle cost,
- b. and secondly, can be provided to customers (utility companies, contractors or other users) either as a finished product, i.e. assembled as a single item, or as a modular product, i.e. their separate individual parts before their assembly, along with the necessary tools and complete manual for their installation and assembly on site.
Specifically:
The poles of the invention consist of two or more (depending on the total height and the desired strength) concave (hollow) parts (tubes) of constant cross-section (cylindrical, polygonal, oval, etc.) which are connected by respective annular joints (connectors) with circumferential grooves on each side.
The concave parts of constant cross sections (tubes) are shaped to serve the operational needs of customers in an optimal way (e.g. cross section with grooves for the easy installation of the cable support fittings, cross section with stiffening ribs, cross section with a channel for cables crossing etc.). They also have appropriate wall thickness to meet customer requirements in terms of the mechanical strength and rigidity of the poles.
Each annular joint connects two successive concave cross sections (tubes) and is shaped so that the one side fits to the upper section and the other side fits to the lower section. The upper side of the joint has a circumferential groove into which the upper section is inserted snugly and ends. Similarly the lower side of the joint has a circumferential groove into which the lower section is inserted snugly and ends. The above design of the joints allows the easy and precise assembly of the poles with simple means.
Adhesive is applied for the welding of the joints with the concave sections, which may be combined with mechanical restraint (e.g. screws, pins, cotter pins, rivets etc.), which is either permanent or temporary (until the adhesive is polymerized) and removable.
The application of the adhesive can be performed by simply spreading into each groove of the joint before placing the respective tube (concave part) in it. It can also be performed by injecting through a special applicator, either in the groove of the joint before placing the respective concave part (as mentioned above), or after the placement of the respective concave part (tube) in the groove of the joint through an appropriately shaped hole, which leads the adhesive into the gap, in order to achieve the welding.
The poles of the invention also have a cap, which fits on the last upper section and is placed on top of the poles ensuring water tightness. The cap has a circumferential groove at its lower side into which the last upper section of the pole is inserted snugly and ends.
Furthermore, the poles of the invention may include additional components (rings, inserts, etc.) and configurations (holes, channels, etc.) according to the user's needs. We indicatively mention, without limitations, the opening of transverse through-holes to the poles, in which internal (reinforcing and guiding) tubes are applied and adhered. These holes are used for passing components, screws and cables (for example, near the top of the pole) or/and for mounting removable steps at regular intervals, allowing technicians to climb and stand in order to perform tasks.
The production method of the poles of the invention has two production steps of the aforementioned individual parts, and an assembly step. The first two steps, which are independent of each other and can be executed in parallel, require specialized industrial equipment, personnel and facilities. In contrast, the assembly step is designed so that it doesn't require specialized personnel or facilities.
Specifically:
The constant cross section concave parts (tubes) of the poles of the invention can be produced by various reinforced polymer production methods (resin transfer molding, contact molding, filament winding, etc.), but are preferably produced by the pultrusion method, which is an industrial, automated, large capacity and competitive method and gives products of reproducible quality and dimensional accuracy.
The annular joints and the cap can also be produced by various reinforced polymer production methods (casting, resin transfer molding, etc.), but are preferably produced by the compression molding method, which also has the same—as abovementioned—characteristics, i.e. industrial, automated, large capacity, competitive, reproducible and accurate in terms of the dimensions of the produced products.
These individual parts of the poles (concave sections, joints and cap), which are produced as abovementioned (by the pultrusion and compression molding methods respectively) are then assembled on a single pole, by using an adhesive and conventional (temporary or permanent) mechanical restraint means (screws, pins, etc.).
The use of the poles of the invention as a modular product is feasible, because the step of the poles assembly provided by their production method is not demanding in terms of expertise, equipment, facilities, utilities, etc., and can therefore be performed by the end user of the poles, with manuals and materials which are delivered together with the poles, even at the site of the final installation of the poles.
Specifically:
The poles of the invention are delivered either fully assembled and ready for installation, i.e. as the existing common poles are delivered, or as a modular product, i.e. divided in its individual parts.
In the second abovementioned case (modular product), the necessary tools, materials and manuals of the on-site assembly are also supplied to the user, along with the parts of the poles to be assembled.
Additionally, the design of the poles of the invention allows their packaging to be used as a modular product in such a way so that the volume required during their transport is submultiple of the volume of the assembled pole. This is done by placing the pieces of smaller cross section (with the corresponding joints) in the pieces of the next larger cross section etc.
In this way the transport of the poles is facilitated and the corresponding cost is reduced, particularly in cases where the poles must be installed in inaccessible locations and in cases where the poles have to be transported over long distances (e.g. exports).
The poles of the invention are suitable for each and every use (power distribution, telecommunications, lighting, etc.).
With the invention the existing cumulative advantages of the poles from FRP are enhanced and expanded compared e.g. with wooden:
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- availability, non-seasonal production
- excellent mechanical strength and elastic, predictable mechanical behavior
- long lifetime without requiring maintenance
- resistance against moisture, environmental attacks and the visible spectrum and UV radiation
- wide temperature operating range
- exemption from the need for impregnation with pesticides to protect against organisms
- repeatability of properties, dimensional stability and alignment
- ability to integrate inserted nuts and mounting parts of the pole equipment
- low weight, easy transportation and installation
- electrical insulation
- better behavior in car crushes, more safety and less damage to the vehicle and the network
- poles that do not sustain combustion (flame retardant)
- fine appearance (more aesthetics options)
- recycling
while the most important advantage of a competitive cost is also added compared to the alternative options, since the poles of the invention have:
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- 1. low production cost due to the industrial production methods used, and
- 2. even lower life cycle cost (total cost of use), which is the sum of the production cost plus the costs of keeping a stock, transporting, handling, installation, inspection, maintenance, etc.) due to their light and modular structure which allows easier transport, since the bulkier individual parts can be placed one within the other requiring a much smaller space, and faster installation with less means, especially when it must be done in inaccessible places.
These enable the successful industrial application of the invention.
The full development and detailed description of the characteristics and the operation of the invention, the production method and the use as a modular product is made by designs (figures), which show poles of the invention consisting of three cylindrical tube parts, with the corresponding joints and cap.
However the use of poles of other cross sections is not excluded (e.g. polygonal, oval, with functional recesses and channels, with stiffening ribs, etc.), representative designs (figures) of which have also been added.
The selection of a smaller or a larger number of pole parts also is not excluded, depending on its height, use and strength required.
The design of poles consisting of successive parts of constant cross-section of different shape (e.g. cylindrical parts at the base for the even distribution of mechanical stresses and polygonal part(s) at the top for the easier mounting of the arms and the support parts of the cables) also is not excluded by appropriately adjusting the shape of the respective joints, in order to fit to the different (upper and lower) sections.
In
Each joint is designed so as to “receive” at appropriately shaped circumferential grooves (recesses) the two cylindrical sections (upper and lower) which it connects, in order firstly to achieve the strong adhesion between the joint and the sections with adhesive, and secondly the assembling of the section to be performed accurately (the sections “end” in the grooves (recesses) of the joint, without the need for measuring, leveling, etc.). All the joints can be produced by the compression molding method. The design of the joints ensures that the successive sections overlap at a small part of their length, so that the connection is resistant against bending.
At the first step of the assembly (A) the joints and the cap are welded to the corresponding lower cylindrical sections, by applying an adhesive (K). The application of the adhesive can be made in all possible ways (spreading, infusion, injection, etc.), depending on the viscosity of the adhesive and the specific design of the joints and the sections. Similarly the type of adhesive application equipment vary (spatula, pressing machine with static mixer, etc.). The welding can also be combined with mechanical restrain, either permanent or temporary, until the completion of the polymerization (hardening) of the adhesive.
The first step of the assembly (A) preferably takes place at the factory (before delivery) even when the pole is delivered as a modular product. This is partly because, after the first step, the individual parts of the pole may still be placed inside one another (in order to be transported easily and inexpensively), and also because by performing the first step at the factory the labor that must be done on-site and the corresponding installation time of the pole are reduced.
At the second step of the assembly (B) the joints are welded to the corresponding upper cylindrical sections, by applying an adhesive (K). In this way the individual assemblies resulted from the first step are joined to form the final pole (C). Regarding the application of the adhesive and mechanical restraint exactly the same are applied as mentioned for the first step. When the pole is delivered as a modular product, the second step is always performed on-site.
More specifically,
Also
All of the figures and images 20-21 and 22-26 describe all the steps of the assembly, packaging for transportation and installation of a modular pole of three stages of the invention, from the production of its individual pieces until the completion of its installation on-site.
In
If the adhesive is applied by injection by an applicator into appropriate for this purpose sockets (holes) of the parts and the joints, then all the steps of the assembly/installation can be preceded (
In
The determination of the individual dimensions of the pieces that form the pole of the example was made by using a finite element software package, taking into account firstly the mechanical stresses and strains that the pole must resist and secondly the resistances of the reinforced polymers from which the pieces are manufactured and the direction of these resistances (compression molding isotropic material for the joints and the cap and pultrusion orthotropic material for the cylindrical parts).
The pole of the example is 7 m long and meets the requirements of the specifications relating to poles of respective size suitable for installation in networks. It also meets the requirements of relevant international standards (EN 50341, EN 50423).
Claims
1. Modular fiber reinforced plastic poles, consisting of two or more successive concave parts of constant cross section of several shapes and sizes, of annular joints of the corresponding shape with circumferential grooves at both their sides suitable for fitting the sections that they connect, and of a cap of corresponding shape, characterized by the fact that each concave part is fitted with the other via the annular joints and the cap is fitted on the top of the upper concave part of the pole.
2. Modular fiber reinforced plastic poles, according to claim 1, characterized by the fact that the concave parts of constant cross section have different shapes and sizes.
3. Modular fiber reinforced plastic poles, according to claim 1, characterized by the fact that the concave parts of constant cross section have similar shapes but different sizes.
4. Modular fiber reinforced plastic poles, according to claim 1, characterized by the fact that the concave parts of constant cross section are cylindrical, polygonal or oval.
5. Modular fiber reinforced plastic poles, according to claim 1, characterized by the fact that inner tubes are transversely passed through holes and welded, for the passing of components, screws, cables and for fixing of removable steps.
6. Modular fiber reinforced plastic poles, consisting of two or more successive concave parts of constant cross section which form an internal channel accessible from the exterior of the pole for passing the cables, of annular joints with circumferential grooves at both their sides suitable for fitting the sections that they connect with the corresponding adjustment of their shape, and of a cap of corresponding shape, assembled in a way that each concave part is fitted with the other via the annular joints and the cap is fitted on the top of the upper concave part of the pole.
7. Modular fiber reinforced plastic poles, consisting of two or more successive concave parts of constant cross section with external grooves along them for fixing components, cables and boxes, of annular joints with circumferential grooves at both their sides suitable for fitting the sections that they connect with the corresponding adjustment of their shape, and of a cap of corresponding shape, characterized by the fact that each concave part is fitted with the other via the annular joints and the cap is fitted on the top of the upper concave part of the pole.
8. Method for producing modular fiber reinforced plastic poles, consisting of two or more concave successive parts of constant cross section, of annular joints of corresponding shape with circumferential grooves at both their sides suitable for fitting the sections that they connect, and of a cap of corresponding shape, characterized by the fact that the concave parts of constant cross sections are produced by the pultrusion method and the annular joints and the cap are produced by the compression molding method.
Type: Application
Filed: Feb 2, 2016
Publication Date: Jan 18, 2018
Inventor: PANAGIOTIS CHRONIS (METAMORPHOSIS, ATTICA)
Application Number: 15/546,898