CA2138781A1 - Support pole for electricity power transmission line - Google Patents
Support pole for electricity power transmission lineInfo
- Publication number
- CA2138781A1 CA2138781A1 CA 2138781 CA2138781A CA2138781A1 CA 2138781 A1 CA2138781 A1 CA 2138781A1 CA 2138781 CA2138781 CA 2138781 CA 2138781 A CA2138781 A CA 2138781A CA 2138781 A1 CA2138781 A1 CA 2138781A1
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- CA
- Canada
- Prior art keywords
- pole
- layer
- fibers
- support pole
- pole according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04H—BUILDINGS OR LIKE STRUCTURES FOR PARTICULAR PURPOSES; SWIMMING OR SPLASH BATHS OR POOLS; MASTS; FENCING; TENTS OR CANOPIES, IN GENERAL
- E04H12/00—Towers; Masts or poles; Chimney stacks; Water-towers; Methods of erecting such structures
- E04H12/02—Structures made of specified materials
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C53/00—Shaping by bending, folding, twisting, straightening or flattening; Apparatus therefor
- B29C53/56—Winding and joining, e.g. winding spirally
- B29C53/58—Winding and joining, e.g. winding spirally helically
- B29C53/583—Winding and joining, e.g. winding spirally helically for making tubular articles with particular features
- B29C53/587—Winding and joining, e.g. winding spirally helically for making tubular articles with particular features having a non-uniform wall-structure, e.g. with inserts, perforations, locally concentrated reinforcements
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C53/00—Shaping by bending, folding, twisting, straightening or flattening; Apparatus therefor
- B29C53/80—Component parts, details or accessories; Auxiliary operations
- B29C53/8008—Component parts, details or accessories; Auxiliary operations specially adapted for winding and joining
- B29C53/805—Applying axial reinforcements
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2031/00—Other particular articles
- B29L2031/766—Poles, masts, posts
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- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Mechanical Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Wood Science & Technology (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Bridges Or Land Bridges (AREA)
- Moulding By Coating Moulds (AREA)
Abstract
A fiber reinforced plastics material pole for electricity power lines comprises a frusto-conical pole structure of tapering diameter and optionally tapering wall thickness from the lower end to the upper end. The structure is formed in three separate layers (37, 38, 39) all of which may vary in thickness including an inner filament wound layer (37), an intermediate layer (38) of directly longitudinal fibers (44, 45, 46) and an outer filament wound layer (39). The longitudinal fibers (44, 45, 46) extend from the lower end and terminate at certain positions (45A, 46A) along the length of the pole to gradually reduce the numbers of fibers so that only some extend along the full length of the pole. The pole is buried and has a filler material (30) to a position above the ground surface to prevent water entry. An outer layer (36) of a fire retardant resin contains a particulate erosion resisting material to protect the pole from soil erosion. The longitudinal fibers can be provided in pre-formed tapered elements (60, 70) arranged to extend longitudinally at spaced positions around the circumference of the pole with the space therebetween decreasing from the bottom toward the top.
Description
SUPPORT POLE FOR ELECTRICITY POWER TRANSMISSION LINE
This invention relates to an electricity power transmission line and particularly to an improved pole construction for supporting the line.
Conventional support poles for electricity power transmission lines, street lamps and the like are formed from steel, concrete or wood.
Wooden poles have the advantages that they are natural, of very low cost for relatively short poles and are readily drillable for attachment of various mounting brackets and the like. In addition wooden poles effectively dampen vibration of the pole to resist galloping of the wires caused by vibration at a natural frequency. The wood poles are however relatively weak for the weight of material and have a significant problem with deterioration. The use of preservatives can prevent deterioration but leads to environmental problems.
While wooden poles are very hard to displace at short lengths for the significant cost advantages, longer lengths of pole become very expensive due to the unavailability of trees of the required dimensions.
Concrete poles are very strong and relatively flexible but have the significant disadvantage of being very heavy, brittle and difficult to drill. The total cost of an installed pole is also dependent upon the cost of transportation and on site installation of the pole and concrete in view of its great weight significantly increases the costs in these areas.
Steel poles are very strong and flexible but have the significant disadvantages of rusting, high cost and being electrically conductive. This leads to increased costs in relation to the insulators necessary to seperate thepower cables from the electrically conductive metal pole.
It has been known for many years, therefore, that there is a sig"iticant advantage in utilizing fiber reinforced plastics material for the manufacture of poles of this type. Many attempts have been made to develop poles manufactured from these materials but up till now the only practical pole construction utilized commercially is that manufactured by Shakespeare of Newbury South Carolina which provides a pole for supporting only lighting and is not suitable for use in supporting electrical power cables where the transverse or bending forces on the pole can be significantly increased.
This invention relates to an electricity power transmission line and particularly to an improved pole construction for supporting the line.
Conventional support poles for electricity power transmission lines, street lamps and the like are formed from steel, concrete or wood.
Wooden poles have the advantages that they are natural, of very low cost for relatively short poles and are readily drillable for attachment of various mounting brackets and the like. In addition wooden poles effectively dampen vibration of the pole to resist galloping of the wires caused by vibration at a natural frequency. The wood poles are however relatively weak for the weight of material and have a significant problem with deterioration. The use of preservatives can prevent deterioration but leads to environmental problems.
While wooden poles are very hard to displace at short lengths for the significant cost advantages, longer lengths of pole become very expensive due to the unavailability of trees of the required dimensions.
Concrete poles are very strong and relatively flexible but have the significant disadvantage of being very heavy, brittle and difficult to drill. The total cost of an installed pole is also dependent upon the cost of transportation and on site installation of the pole and concrete in view of its great weight significantly increases the costs in these areas.
Steel poles are very strong and flexible but have the significant disadvantages of rusting, high cost and being electrically conductive. This leads to increased costs in relation to the insulators necessary to seperate thepower cables from the electrically conductive metal pole.
It has been known for many years, therefore, that there is a sig"iticant advantage in utilizing fiber reinforced plastics material for the manufacture of poles of this type. Many attempts have been made to develop poles manufactured from these materials but up till now the only practical pole construction utilized commercially is that manufactured by Shakespeare of Newbury South Carolina which provides a pole for supporting only lighting and is not suitable for use in supporting electrical power cables where the transverse or bending forces on the pole can be significantly increased.
2 1 3 8 7 ~1 ~` PCT/CA94/00206 However attempts are being made by Shakespeare to introduce a pole of this type for supporting eiectrical power cables in 1994.
The Shakespeare pole is manufactured by filament winding techniques in which fibers impregnated with resin are wrapped helically around a central mandrel to form a wall thickness of the required amount. The central mandrel is then removed after curing of the resin to leave the finished pole which can then be coated by various techniques to provide an attractive and resistant outer surface.
Various other techniques have been proposed for manufacture of poles for supporting lighting, electric power cables and the like. For proper reinforcement of the pole structure, it is known that both longitudinal and transverse fibers are required. A number of techniques are proposed for providing such arrangement of fibers. Pultrusion is a well known technique in which parts are formed of a consLanl cross section by drawing through a dye resin impregnated fibrous materials which are continuous along the length of the structure. The majority of the fibers in such a structure are longitudinal but some transverse fibers can be added by the addition of woven or non woven mat which'has the combination of longitudinal and transverse fibers. One example of a pole of this type is shown in U.S. Patent 4,803,819 (Kelsey~ and described in a paper dated 1987 relating to a product designed by 3-P
Industries Inc. of Toms River NJ. This arrangement provides a pole of constant transverse cross section which is an essential result of the pultrusion process.In order to provide the required structural sL~enylh for this pole, a complex cross section is necessary including transverse webs both internally and externally of a main longitudinal cylindrical shape of the pole. It is understood that this arrangement has not achieved significant commercial success. The constant cross section of pultruded poles of this type is unsatisfactory since it does not maximize the strength to weight characteristics and since the constant cross section thus formed is significantly less resistant to damaging vibrations than are tapered poles. In addition the limited amount of transverse fibers that can be included significantly reduces the resistance of the pole to .! ~ ;
WO 94/26501 2 1 3 8 7 ~1 PCT/CA94/00206 transverse collapse thus requiring the complex transverse elements of the cross section which are difficult and expensive to manufacture.
Filament winding provides another technique for providing both the longitudinal and transverse fibers. In this technique the fibers are wound helically about the central axis of the pole. It is of course possible to control the helix angle so that at some point along the length of the pole the helix angle is very shallow that is close to 90 to the axis. At other points along the length of the pole the helix can be stretched out to approximate to longitudinalfibers. However it is certainly not possible to apply such fibers directly longitudinally since it is necessary to maintain some degree of helix angle to hold the fibers in place on the structure. It will be appreciated that complex computer control of the winding can be effected both in relation to the helix angle and the reversal points of the helix to maximize structural strength. In addition the shape and wall thickness of the pole can be varied again to maximize strength both in relation to the taper of the pole and the thickness ofthe wall of the pole at various positions along the length of the pole. However these techniques have failed to produce an acceptable pole suitable for carryingelectric power cables and the only commercial development is the Shakespeare pole described above. This a"ange",ent is shown in a catalogue of Shakespeare which shows the various products available. A further example is shown in a paper published in October 1980 which refers to a pole of this type manufactured by W.J. Whatley Inc. of Commerce City CO.
Another technique for manufacturing fiber reinforced plastic material is the lay-up technique in which chopped fibers are applied in a resin material to a supporting surface generally in random manner. This technique certainly does not maximize the ~llel-g~l, characteristics of the fibers and is by itself totally unsuitable for manufacture of products such as poles which require maximization of the structural strength.
Another technique for manufacturing is described in a report prepared by Abco Plastics of Nova Scotia Canada dated July 12 1982 which uses centrifugal casting for laying fibers on the inside of a rotating surface.
The fibers are necessarily chopped to relatively short length less than three 2138~81 WO 94/26501 1 . PCT/CA94/00206 ~
? ~
inches. Some attempt is made to lay some of the fibers longitudinally although the paper does not describe how this is achieved. The paper concludes that no further development will be carried out partly due to economic reasons. No commercially viable product is produced as a result of the report.
Further attempts have been made to manufacture poles of this type using combinations of the above techniques. Thus U.S. Patent 4,769,967 and 4,878,984 (Bourrieres) disclose a technique for manufacturing a pole for supporting electrical power transmission lines which includes the combination of an inner pultruded structure around which is applied a filament wound layer.
This construction necessarily provides a pole which is initially of constant cross section even though it may be possible to vary the thickness of the filament wound layer to provide some degree of taper. However the limitations of the initial pultrusion process prevent the maximization of the strength characteristics of the part.
A paper from 1974 by Martin and Richter entitled "A Marketing Approach to the Development of the RP/C Lighting Pole Market" provides an analysis of the products available at that time. Figure 1 of the paper refers to a number of techniques for manufacture of "fiberglass" poles that is poles of fiber reinforced plastic material. These include the following 3 - pultruded mat and roving 4 - pultruded FRP rods sandwiched in glass fabric 5 - composite of spray-up, axial roving and filament winding 6 - filament wound 65 7 - glass cloth on cardboard cylinder 8 - pultruded axial rovings with 90 filament wind 9 - filament wound at low angle with some 90 angle.
The general conclusion of the paper is that none of the poles have been developed to a sufficient standa~d to meet the requirements. Pole Number 8 is stated to provide the best stiffness.
U.S. Patent 3,813,837 (McClain) discloses a further attempt at a combination structure in which an initial lay-up layer of chopped fibers is applied around an inner band of a support material mounted on a finned shape mandrel with a layer of filament wound fibers wrapped around the initial lay up layer.
The conclusion therefore can be drawn that there remains a significant opportunity for the manufacture of a pole of fiber reinforced plastics material which has the required structure to maximize structural strength. It will be appreciated that poles of fiber reinforced plastics material necessarilyprovide the advantages of lightness, flexibility, reduced corrosion, non electrical conductiveness. The advantages are therefore readily available, the requirement however remains to provide a structure which can be manufactured economically, provide the required structural strength and competes with the other available materials in structural performance.
According to the invention, therefore, there is provided an electrically powered transmission line comprising at least one power cable and a plurality of support poles arranged at spaced positions along the length of the cable, each pole comprising a pole body which is shaped as a tapered, holiow frustum surrounding a straight longitudinal axis thus having a cross section which has a hollow interior and reduces in outside and inside dimensions from a lower end of the pole to an upper end of the pole body, the pole body being formed from a fiber reinforced plastics material, the pole body including a first layer which is reinforced by fibers wound substantia!ly circumferentially of theaxis and a second layer coaxial with the first layer which is reinforced by fibers extending generally longitudinally of the axis.
The tapered construction of the pole achieved by the present invention is effectively essential to provide the required structural strength and stiffness. A tapered pole reduces the weight of the pole at the upper end thus reducing the requirement for strength at the lower end. More importantly the reduction in diameter of the pole at the upper end minimizes the wind contact area so as to minimize transverse loading. Furthermore the reduction in weight of the pole at the upper end reduces the momentum of any transverse flexing.
It will be appreciated that the stiffness of the pole to resist bending is of much greater importance than the longitudinal sl,el~ll,. In most cases the characteristics of the pole are measured by the stiffness, that is the degree of -WO 94/26501 213 8 7 81 PCT/CA94/00206 ~
bending in response to a predetermined transverse load. The tapered pole has significant advantages in damping transverse vibrations and this is essential for power lines where wind movement can cause "galloping" of the wires unless the vibrations in the pole are sui~ably dampened.
It is highly preferred that the longitudinal fibers extend directly parallel to the axis, that is, there is no helical twist. These fibers cannot beapplied by the pultrusion technique in view of the taper of the pole and are very difficult to apply using known filament winding techniques or centrifugal casting techniques as described herein before.
It is further highly preferred that the longitudinal fibers are covered on the outer surface thereof and on the inner surface thereof by transverse or circumferential fibers. Such transverse fibers act to resist or prevent cracking of the part longitudinally which could otherwise occur should the longitudinal fibers be presented at a surface of the par~ as well as to resist buckling. The transverse bending forces have little effect on such transverse fibers and hence are unlikely to generate such cracks at the surface. However continued flexing of an arrangement in which the longitudinal fibers are available at the surface could generate longitudinal cracks leading eventually to failure of the part. Such transverse fibers are preferably applied by the circumferential winding technique but also could be applied simply by additionallayer of woven mat or the like.
Filament winding is a technique in which a band of parallel rovings are brought to the mandrel Iying in a plane longitudinal to the mandrel.The mandrel is then rotated so that the band is drawn circumferentially around the mandrel. Relative movement is then provided between the band and the mandrel gradually longitudinally of the axis. The band thus is theoretically applied in a helical manner, but in practical terms some of the fibers may lie directly above previously laid fibers or may even move contrary to the longitudinal movement due to the tendency to fall back or to slip back and forthover one another. In some cases the helix angle can be increased. In the specification, therefore, the term "helically wound" is intended to refer to this WO 94/26501 ~ 1. 3 8 7 81 PCT/CA94/00206 type of filament winding and the term is intended to be synonymous with the term "circumferentially wound".
It is preferable that the structure include three layers including the first layer on the inner surface of the structure which is helically wound. The second layer is the longitudinal layer which is then applied on the outside surface of the first layer and surrounds the first layer. The third layer is again a helical layer applied around the first layer. It is preferable that the first and third layers constitute the inner and outer layers respectively to provide the required hoop strength for the structure to prevent transverse collapse of the tubular body in a buckling mode.
Preferably each of the layers decreases in thickness from the lower end of the pole to the upper end. In particular the central or second layer may decrease in thickness and certainly decreases in volume of fiber. This is achieved by the technique of terminating some of the fibers which extend from the lower end at a position intermediate the length of the pole so as to gradually reduce the number of fibers extending along the length of the pole from a lower end to the upper end. Some of the fibers extend the full length of the pole while others therefore are cut off or terminated at a predetermined position short of the upper end. It will of course be appreciated that, since the diameter of the pole decreases from the lower to the upper end, the volume of fibers applied longitudinally must decrease proportionally or the thickness of the layer will increase.
One embodiment of the invention will now be described in conjunction with the accompanying drawings in which:
Figure 1 is an isometric view of an electric power transmission line according to the present invention.
Figure 2 is side elevational view of a second embodiment of power transmission line according to the present invention.
Figure 3 is a vertical cross sectional view through a pole according to the present invention.
Figure 4 is a cross sectional view along the lines 4-4 of Figure 3.
WO 94/26501 2 ~ ~ 8 7 ~1 PCTICA94/00206 o Figure 5 is a cross sectional view similar to that of Figure 3 on a smaller scale showing the burial of the pole in the ground.
Figure 6 is a cross sectional view similar to that of Figure 4 showing a modified arrangement of the second layer including portions of increase thickness.
Figure 7 is a longitudinal cross sectional view through a further pole construction showing an alternative technique for forming the longitudinal fiber section.
Figure 8 is a cross sectional view along the lines 8-8 of Figure 7.
Figure 9 is a cross sectional view along the lines 9-9 of Figure 7.
Figure 10 is a cross sectional view along the lines 10-10 of Figure 7.
Figure 11 is a cross sectional through a pole of similar construction to that of Figure 7 showing a yet further arrangement for forming the longitudinal fiber-section.
An electricity power transmission line is indicated generally at 10 in Figure 1 and includes power cables 11 mounted on pole structures 12 and 13. In Figure 1 the pole structures 12 and 13 comprise composite pole structures including seperate poles 14 and 15 and a transverse coupling frame generally indicated at 16. In Figure 2 an alternative form of pole structure forthe transmission line is shown which includes a single pole 18 with three seperate arms 19, 20 and 21. Each of the poles 14, 15 and 18 is formed in the manner set forth hereinafter and is buried in the ground surface so as to stand vertically upwardly from the ground surface and supported by the ground.
The structure of the pole is shown in Figures 3, 4 and 5. Thus, as shown in Figure 5, the pole comprises a pole body 23 which is shaped as a frustum of circular cross section. Other cross sections, however can be used.
Thus the body tapers in outside dimension from an upper end 24 to a lower end 25 gradually increasing in diameter toward the lower end 25. Preferably, although not essentially the thickness of the body between an outside surface 26 and an inside surface 27 gradually increases from the upper end 24 to the lower end 25. This shape including the degree of taper of the body as a whole WO 94/26501 21~ 8 7 ~1 PCT/CA94/00206 .
and the degree of the taper of the thickness of the body can be carefuliy calculated to provide the maximum sL~engLh for the body. As one example, the dimensions of the pole may be 60 feet in length tapering from a lower diameter of the order of 18 to 24 inches to an upper diameter of the order of 8 to 10 inches. The thickness of the wall is of the order of 3/8 inch to 1 /2 inch. It will be appreciated that this thickness is relatively thin in comparison with the diameter. It is therefore possible that the thickness may also taper toward the upper end but this is not in any way essential.
A cap 28 is applied on the upper end 24 to provide a closure to prevent entry of water or other materials through the upper end. The cap as shown includes a plug portion 29 extending into the hollow interior of the pole body 23 together with a top portion extending over the hollow interior and outwardly to cover the annular upper end of the pole body.
In the embodiment shown in Figure 5, a lower part of the pole body is filled with a solid filler material 30 such as conc-eL~ or a foamed polymer and the like which extends from the lower end 25 to a height above the ground surface 31. Thus the lower end of the pole is buried into the ground to a conventional depth suitable to support the pole wholly by its engagement with the ground and the conc~ete or other filler material fills the area of the pole up to the ground surface and beyond the ground surface so that the pole is prevent from receiving water on the interior which could act in a freeze/thaw cycle to cause cracking of the pole body. Between the filler material and the inside surface of the pole body is provided a layer of sealant 32 which engages over the inside surface to a height of the solid filler material. The sealant material 32 also extends as indicated at 32A around the exposed lower end of the body 23 so as to prevent the entry of moisture into the interstices in the body and wicking of the moisture along the length of the body which would again cause cracking of the part in a freeze/thaw cycle.
Also shown in the embodiment of Figure 5, the hollow interior between the upper edge of the filler 30 and the underside of the cap 28 is filled with a lightweight foamed filler 33 which prevents further the entry of any materials into the hollow interior and which also provides some structural WO 94/26501 213 8 7 81 PCT/CA94/00206 ~
stability for the body 23. As is well known one process by which a tubular body can be broken is by transverse buckling collapse of the walls of the body thus allowing bending at the collapsed location. This transverse collapse is resisted by the foamed filler materials 30 and 33.
In an alternative arrangement a single filler material can extend along the full length of the body and this will generally be of a light weight foamed material which resists the penetration of water and also provides some structural strength against buckling. The sealant layer 32 may be provided only on the axial end face of the body at the lower end as indicated at 32A.
On the outside surface of the body extending from the lower end 25 to a height above the ground is provided an outer layer 34 which is applied on the outer surface 26. This outer layer is formed of a resin 35 and a particulate filler material 36. The resin 35 is selected to be of a type which is resistant to combustion so that fires at the ground level will not cause combustion of the body 23 due to the resistance of the outside layer 34 as well as to in part suitable weathering resistance properties to the outside surface of the pole. The height of the layer above the ground is selected to provide fire retardancy up to an expected height to which fire could reach in the circumstances of a brush fire or the like. The filler material 36 can be of sand, glass flakes or the like which becomes exposed at the surface of the resin.
This also acts as a fire retardant but also acts to reduce erosion or stripping of the resin at the surface due to soil movement in high winds and the like as wellas imparting a weathering resistant outer surface with respect to UV exposure and subsequent erosion.
The detailed structure of the body is shown in more detail in Figures 3 and 4. Thus the body is formed from a plurality of layers including the sealant layer 32, a first filament wound layer 37, a second longitudinal layer 38, a third filament wound layer 39, and the outer layer 34. In addition an optional wrapping layer 40 can be provided outside the second longitudinal layer 38.
Thus the structural sl,enyll~ of the body is formed from a composite of mainly the three layers 37, 38 and 39. Each of these layers ~ WO 94/26501 2 13 8 7 ~1 PCT/CA94/00206 varies in thickness so that the thickness of the layer gradually decreases from the lower end 25 to the upper end 24.
in the layer 37, the layer is formed from filament wound reinforcing fibers which are impregnated with resin material so as to form a layer of fiber reinforced plastics material. The filament wound fibers are wrapped around a longitudinal axis of the body generally by rotating a mandrel on which the body is formed about the axis 41. The fibers are laid generally circumferentially but with a slight helix angle only slightly differing from an angle directly at 90 to the axis 41. Thus it is intended that the fibers in thelayer 37 are generally circumferential in direction rather than having any significant longitudinal components. This layer thus provides circumferential hoop strength for the body. When required, the variation in thickness of the layers is obtained by reducing the number of wraps indicated at 42 and 43 in the layer 37 which thus gradually decreases along the length of the layer.
In the layer 38, there is provided an impregnating resin and a plurality of supporting fibers 44, 45 and 46 which are shown of course only schematically. In the layer 38 the fibers are intended to have as their major component of direction a direction essentially longitudinal of the part. Thus some of the fibers indicated schematically at 44 extend from the lower end 25 of the body wholly along the full length of the body to the upper end 24. The fibers 44 thus extend directly parallel to the axis 41 and lie in axial planes. Of course the fibers 44 as illustrated represent a series of fibers arranged at angularly spaced positions around the axis 41 within the layer 38.
As stated above, in order to maintain the thickness of the layer 38 constant or in order to reduce the thickness of the layer 38 from the lower end toward the upper end it is necessary to reduce the volume of fibers along the length of the pole body. This is achieved in that some of the fibers as indicated at 45, 46 commence at the lower end 25 but then terminate at positions 45A and 46A at spaced positions along the length of the layer. Again it will be appreciated that the fibers illustrated at 45 and 46 represent a whole series of fibers spaced angularly around the axis 41 all of which terminate at the positions as shown. This provides in effect a series of groups of fibers all WO 94/26501 2 ~ 3 8 7 8 1 ~ PCTICA94/00206 1 of which terminate at progressively group positions along the length of the body.
Turning now to Figure 4, the fibers of the layer 38 are formed generally of a first type of fiber but in four zones 38A spaced angularly aroundthe axis 41 a second type of fiber is blended with the first type. As shown schematically, there are four such zones of blended fibers arranged at the 12:00, 3:00, 6:00 and 9:OO positions. These positions correspond to directions longitudinal of and transverse to intended direction of the power cable. The main bulk of the fibers in the layer 38 are formed from glass as these are inexpensive and provide generally satisfactory structural strength.
However in the zones 38A fibers of a different type can be blended with the glass fibers to provide different strength/stretch characteristics. One problem with glass fibers is they tend to have a low modulus of elasticity so that theremay be in some cases a reduced dampening effect on transverse vibrations in the finished pole. This tendency can be improved by providing additional fibers of an increased elasticity in the zones 38A, bearing in mind that such fibers will be of significantly increased cost relative to the standard glass fibers.
In Figure 6 is shown a further modified arrangement in which the layer 38 is increased in thickness at four zones corresponding to the longitudinal and transverse positions of the power cable. At these zones the number of longitudinal fibers is significantly increased so as to define a lobe on the outside surface of the body generated by this additional longitudinal fibers.
In the embodiment shown there are four such lobes indicated at 38B. In an alternative arrangement only two such lobes may be provided either in the longitudinal or transverse positions in accordance with technical requirements to provide the desirable stiffness or resistance to bending.
The second layer 38 has an inner surface which is tapered, an outer surface which is also tapered and a thickness which varies. This layer cannot therefore be formed by pultrusion which of course requires a constant transverse cross section along the full length of the part. In addition the second layer is provided outside the inner layer which is already formed by the filament winding technique.
~ WO 94/26501 2 1~ 8 7 81 PCT/CA94/00206 The third filament wound layer 39 is formed on the outside of the second longitudinal layer 38 and again extends along the full length of the bodyand is formed by helically wound fibers as described in relation to the inner layer 37. The thickness of the third layer can be increased in the area of the outer layer 34 as shown in Figure 5 to provide an increased structural strength in that area and increased resistance to erosion. In addition the layer 39 has an increased thickness as indicated at 39A in a band at the top of the pole for receiving the transverse coupling members 16 or for receiving the support bars 19, 20, 21. The mounting arrangement for the coupling bars is not shown but could include a band clamped around the pole at the thickened band 39A and fastened thereto by a clamping action or by bolt and sleeve arrangement passing through the body 23.
In Figure 3 the outer layer 34 is shown to extend along the full length of the body. However the outer layer can be modified at the height shown in Figure 5 in the particulate reinforced material to a simply a resin layer or resin rich layer on the outside of the layer 39. Other coatings may be used such as epoxy, vinyl, polyester urethane, silicone simply to provide an attractive appearance and resistance to damage.
In Figure 3 is shown a modified technique for reinforcement of the internal structure of the body 23 and this comprises an elongate cable or rod 50 which carries a plurality of transverse discs 51 which are engaged against the inside surface 27. The rod 50 can be a complete longitudinal rod extending along the full length of the pole. Alternatively the rod can be formedin segments with each segment attached to the underside of one disc and the upper side of the next adjacent disc. Such an arrangement automatically spaces the discs at the required spacing along the length of the structure without the necessity of providing locating elements on the rod. These again therefore provide resistance to transverse collapse of the inside surface. In alternative arrangements the body can be completely hollow from the cap down to the solid insert 30 with the necessary structural strength being provided solely by the layers 37, 38 and 39. ~
W094/26501 213 8 ~ ~ ~ PCT/CA94/00206 ~
r The length of the pole is preferably greater than 60 feet. Up to this height, the cost of the composite materials is such that it is very difficult to compete with the very inexpensive wooden poles which are readily available.
However above this height the cost of wooden poles dramatically increases and in addition the increased cost of the composite material type pole provides sufficient advantages over the existing wooden poles to justify the increased cost. Shorter poles may be used in situations where the wooden poles are found to be a significant environment problem.
The layers can be formed by various techniques. In general the inside layer 37is formed on the outside surface of an existing mandrel which is subsequently intended to be removed from the structure. The inside layer is thus fully formed by a filament wrapping technique, as is well known, along the full length of the mandrel from the lower end 25 to the upper end 24 of the pole. The longitudinal layer 38is then formed by laying the fibers longitudinally on the already formed inner layer 37 and cutting the groups 45, 46 as required.
The fibers can be laid longitudinally by grasping all of the fibers at the lowerend just beyond the end of the body and the mandrel and then pulling the fibers longitudinally while cutting those fibers that need to be cut. The wrapping layer 40 can then be applied behind the fibers as they are pulled longitudinallyof the mandrel simply to hold the longitudinal fibers in place prior to the set~ing of the resin. After the longitudinal fibers are fully laid and wrapped so that they are held in place, the third layer 39 can be applied by rotating the mandrel carrying the layers 37,38 and 40 to apply the third structural layer. Setting ofthe resin can be effected in three seperate stages or alternatively the three layers can be applied before the resin is set by selecting suitable time constants for the resin or by actuating the resin by heat or other known techniques. In a particularly prefer,ed arrangement, the longitudinal fibers are applied by moving the mandrel carrying the inner layer 37 longitudinally of a wrapping station which applies fibers fully around the layer 37 as the mandrel moves longitudinally. Behind the station which applies the longitudinal fibers is provided a wrapping station which provides fibers of the wrapping layer 40 ~ WO 94/26501 213 8 7 81 PCT/CA94/00206 wrapped helically around the layer 38 to hold the fibers in place. Subsequently the layer 39 is applied by rotating the mandrel.
In a further alternative, the longitudinal fibers can be laid up on the outer surface of the layer 37 by forming the fibers into a blanket which is then wrapped around the outer surface of the layer 37 and held in place by a wrapping system defined in layer 40. The blanket may be carried by a sheet which is then removed before the wrapping layer 40 is applied.
While the inner filament wound layer 37 and the outer filament wound layer 39 may be formed of fibers which are wrapped with a very shallow helix angle that is close to a plane at right angles to the axis of the pole, in some cases some or all of the fibers may be wrapped with a larger helixangle. This increased helix angle can assist in transmitting loads around the layer to resist buckling forces.
Turning now to Figures 7 through 10, an alternative arrangement is shown for forming the longitudinal fiber layer indicated generally at 60. As previously described an inner layer 61 of helically wrapped fibers is provided on the inside surface of the layer 60 and in addition an outer layer 62 of helically wound fibers is applied on the outside surface of the longitudinal layer 60. Thefurther layers and reinforcement materials described herein before are omitted for convenience of illustration.
In the construction of Figures 7 through 10, the longitudinal fiber layer is formed by a plurality of pultruded strips formed of fiber reinforced resin material. As shown in the cross section of Figure 8, the strips 63, 64, 65 etc.
are formed into a stack having a width very much less than the circumference of the pole. Thus for example in a pole having an initial bottom diameter of 24 inches, so the circumference is approximately 80 inches, the stack will have a width W in the range 0.25 to 3.0 inches preferably of the order of 1.5 inches.
Each strip in the stack has a thickness in the range 0.030 to 0.25 inches and preferably of the order of 0.05 inches so that approximately twelve strips are necessary at the base of the pole to complete the full thickness of the layer asindicated at T. Each of the strips forming the single stack has the same width W. In this way the cross section of the stack is rectangular. As shown in WO 94/26501 213 8 7 ~ PCT/CA94/00206 Figure 7, the inner most one of the strips 63 extends along the full length of the pole and forms the full extent of the longitudinal layer. The strips 64, 65 etc.are of reduced length relative to the strip 63 so as to form a staggered arrangement in which an outer most one of the strips indicated at 66 terminates at an upper end 67. Each further strip inwardly of the outermost strip then terminates at an upper end of that strip with the upper ends being staggered along the length of the pole to gradually reduce the thickness of the longitudinal layer 60. In an aller"ali~e arrangement (not shown) the continuous strips along the full length of the pole can be arranged on the outside of the stack. In a further alternative continuous strips can be arranged on the inside and the outside to increase stability of the stack, with the shorter strips in between the inner and outer strips and therefore protected thereby. As the strips are thin, the discontinuities can be bridged without difficulty.
In order to prevent penetration of moisture between the stacks from causing damage, the spaces between the stacks can be filled with a foam such as a polyester foam which is compatible with the type of resin used with the fibers. One type of polyester foam can be arranged to effect foaming without curing so that the foamed but uncured material can be inserted into the spaces and covered with the outer wrapping layer of fibers and resin while any uncured foam is simply displaced by the wrapping layer or absorbed by it.
As shown in Figure 8, the stacks of strips are arranged at spaced positions around the periphery of the pole. As the diameter of the pole tapers inwardly, the spacing between the stacks gradually decreases. Thus the spacing at Figure 8 is indicated at S1 and the spacing in Figure 9 at a positionpartway up the pole is indicated at S2. At the top of the pole as indicated in Figure 10,the spacing is reduced effectively to zero so that the edges of the strip 63 are effectively in contact as indicated at 63A thus forming effectively a continuous layer around the full periphery of the pole at the top end of the pole.
The layers forming each stack are bonded together by suitable adhesive or resin material so as to form effectively an integral stack. In addition the inside surface of the layer 63 is bonded to the layer 61 and similarly the outside surface of the layer 66 is bonded to the outer layer 62.
~ WO 94/26!;01 2 i 3 8 7 81 PCT/CA94/00206 This forms the whole structure into an integral structure. The bonding can be effected using the resin material within which the fibers are embedded, with the time constance of the setting of the resin being arranged to effect the bonding during the manufacturing process.
The alternative arrangement shown in Figure 11 is very similar to that of Figures 7 through 10 except that the longitudinal layer is formed from aplurality of longitudinal elements equivalent to the stacks of Figures 7 through10. In this case, however, the longitudinal elements are formed in wedge shape so that a single element 70 tapers from a lower end 71 to an upper end 72 with that taper being gradual and continuous along the full length of the element. Such elements can be formed by cutting diagonally a pultruded bar of rectangular cross section. Thus the diagonal cutting forms two such elements one of which is then inverted so that the bottom end is the thicker end and the top end is the thinner end. The cross section of the pole as shown in Figure 11 will therefore be very similar to that shown in Fi3ures 8, 9 and 10 except that each longitudinal element 70 will not be formed from separate layers.
The layers of the stacks of Figure 7 and the individual elements of Figure 11 which are then cut to form the wedge shaped members are formed by pultrusion using conventional technique so that the reinforcing fibers of thelayers and elements are directly longitudinal.
- The layers thus defined above provide a totally unique structure for the composite fiber reinforced plastics material pole which cannot be formed by the conventional techniques of pultrusion, lay-up, filament winding orcentrifugal casting techniques but require the directly longitudinal fiber placement as explained herein before.
Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without departing from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.
The Shakespeare pole is manufactured by filament winding techniques in which fibers impregnated with resin are wrapped helically around a central mandrel to form a wall thickness of the required amount. The central mandrel is then removed after curing of the resin to leave the finished pole which can then be coated by various techniques to provide an attractive and resistant outer surface.
Various other techniques have been proposed for manufacture of poles for supporting lighting, electric power cables and the like. For proper reinforcement of the pole structure, it is known that both longitudinal and transverse fibers are required. A number of techniques are proposed for providing such arrangement of fibers. Pultrusion is a well known technique in which parts are formed of a consLanl cross section by drawing through a dye resin impregnated fibrous materials which are continuous along the length of the structure. The majority of the fibers in such a structure are longitudinal but some transverse fibers can be added by the addition of woven or non woven mat which'has the combination of longitudinal and transverse fibers. One example of a pole of this type is shown in U.S. Patent 4,803,819 (Kelsey~ and described in a paper dated 1987 relating to a product designed by 3-P
Industries Inc. of Toms River NJ. This arrangement provides a pole of constant transverse cross section which is an essential result of the pultrusion process.In order to provide the required structural sL~enylh for this pole, a complex cross section is necessary including transverse webs both internally and externally of a main longitudinal cylindrical shape of the pole. It is understood that this arrangement has not achieved significant commercial success. The constant cross section of pultruded poles of this type is unsatisfactory since it does not maximize the strength to weight characteristics and since the constant cross section thus formed is significantly less resistant to damaging vibrations than are tapered poles. In addition the limited amount of transverse fibers that can be included significantly reduces the resistance of the pole to .! ~ ;
WO 94/26501 2 1 3 8 7 ~1 PCT/CA94/00206 transverse collapse thus requiring the complex transverse elements of the cross section which are difficult and expensive to manufacture.
Filament winding provides another technique for providing both the longitudinal and transverse fibers. In this technique the fibers are wound helically about the central axis of the pole. It is of course possible to control the helix angle so that at some point along the length of the pole the helix angle is very shallow that is close to 90 to the axis. At other points along the length of the pole the helix can be stretched out to approximate to longitudinalfibers. However it is certainly not possible to apply such fibers directly longitudinally since it is necessary to maintain some degree of helix angle to hold the fibers in place on the structure. It will be appreciated that complex computer control of the winding can be effected both in relation to the helix angle and the reversal points of the helix to maximize structural strength. In addition the shape and wall thickness of the pole can be varied again to maximize strength both in relation to the taper of the pole and the thickness ofthe wall of the pole at various positions along the length of the pole. However these techniques have failed to produce an acceptable pole suitable for carryingelectric power cables and the only commercial development is the Shakespeare pole described above. This a"ange",ent is shown in a catalogue of Shakespeare which shows the various products available. A further example is shown in a paper published in October 1980 which refers to a pole of this type manufactured by W.J. Whatley Inc. of Commerce City CO.
Another technique for manufacturing fiber reinforced plastic material is the lay-up technique in which chopped fibers are applied in a resin material to a supporting surface generally in random manner. This technique certainly does not maximize the ~llel-g~l, characteristics of the fibers and is by itself totally unsuitable for manufacture of products such as poles which require maximization of the structural strength.
Another technique for manufacturing is described in a report prepared by Abco Plastics of Nova Scotia Canada dated July 12 1982 which uses centrifugal casting for laying fibers on the inside of a rotating surface.
The fibers are necessarily chopped to relatively short length less than three 2138~81 WO 94/26501 1 . PCT/CA94/00206 ~
? ~
inches. Some attempt is made to lay some of the fibers longitudinally although the paper does not describe how this is achieved. The paper concludes that no further development will be carried out partly due to economic reasons. No commercially viable product is produced as a result of the report.
Further attempts have been made to manufacture poles of this type using combinations of the above techniques. Thus U.S. Patent 4,769,967 and 4,878,984 (Bourrieres) disclose a technique for manufacturing a pole for supporting electrical power transmission lines which includes the combination of an inner pultruded structure around which is applied a filament wound layer.
This construction necessarily provides a pole which is initially of constant cross section even though it may be possible to vary the thickness of the filament wound layer to provide some degree of taper. However the limitations of the initial pultrusion process prevent the maximization of the strength characteristics of the part.
A paper from 1974 by Martin and Richter entitled "A Marketing Approach to the Development of the RP/C Lighting Pole Market" provides an analysis of the products available at that time. Figure 1 of the paper refers to a number of techniques for manufacture of "fiberglass" poles that is poles of fiber reinforced plastic material. These include the following 3 - pultruded mat and roving 4 - pultruded FRP rods sandwiched in glass fabric 5 - composite of spray-up, axial roving and filament winding 6 - filament wound 65 7 - glass cloth on cardboard cylinder 8 - pultruded axial rovings with 90 filament wind 9 - filament wound at low angle with some 90 angle.
The general conclusion of the paper is that none of the poles have been developed to a sufficient standa~d to meet the requirements. Pole Number 8 is stated to provide the best stiffness.
U.S. Patent 3,813,837 (McClain) discloses a further attempt at a combination structure in which an initial lay-up layer of chopped fibers is applied around an inner band of a support material mounted on a finned shape mandrel with a layer of filament wound fibers wrapped around the initial lay up layer.
The conclusion therefore can be drawn that there remains a significant opportunity for the manufacture of a pole of fiber reinforced plastics material which has the required structure to maximize structural strength. It will be appreciated that poles of fiber reinforced plastics material necessarilyprovide the advantages of lightness, flexibility, reduced corrosion, non electrical conductiveness. The advantages are therefore readily available, the requirement however remains to provide a structure which can be manufactured economically, provide the required structural strength and competes with the other available materials in structural performance.
According to the invention, therefore, there is provided an electrically powered transmission line comprising at least one power cable and a plurality of support poles arranged at spaced positions along the length of the cable, each pole comprising a pole body which is shaped as a tapered, holiow frustum surrounding a straight longitudinal axis thus having a cross section which has a hollow interior and reduces in outside and inside dimensions from a lower end of the pole to an upper end of the pole body, the pole body being formed from a fiber reinforced plastics material, the pole body including a first layer which is reinforced by fibers wound substantia!ly circumferentially of theaxis and a second layer coaxial with the first layer which is reinforced by fibers extending generally longitudinally of the axis.
The tapered construction of the pole achieved by the present invention is effectively essential to provide the required structural strength and stiffness. A tapered pole reduces the weight of the pole at the upper end thus reducing the requirement for strength at the lower end. More importantly the reduction in diameter of the pole at the upper end minimizes the wind contact area so as to minimize transverse loading. Furthermore the reduction in weight of the pole at the upper end reduces the momentum of any transverse flexing.
It will be appreciated that the stiffness of the pole to resist bending is of much greater importance than the longitudinal sl,el~ll,. In most cases the characteristics of the pole are measured by the stiffness, that is the degree of -WO 94/26501 213 8 7 81 PCT/CA94/00206 ~
bending in response to a predetermined transverse load. The tapered pole has significant advantages in damping transverse vibrations and this is essential for power lines where wind movement can cause "galloping" of the wires unless the vibrations in the pole are sui~ably dampened.
It is highly preferred that the longitudinal fibers extend directly parallel to the axis, that is, there is no helical twist. These fibers cannot beapplied by the pultrusion technique in view of the taper of the pole and are very difficult to apply using known filament winding techniques or centrifugal casting techniques as described herein before.
It is further highly preferred that the longitudinal fibers are covered on the outer surface thereof and on the inner surface thereof by transverse or circumferential fibers. Such transverse fibers act to resist or prevent cracking of the part longitudinally which could otherwise occur should the longitudinal fibers be presented at a surface of the par~ as well as to resist buckling. The transverse bending forces have little effect on such transverse fibers and hence are unlikely to generate such cracks at the surface. However continued flexing of an arrangement in which the longitudinal fibers are available at the surface could generate longitudinal cracks leading eventually to failure of the part. Such transverse fibers are preferably applied by the circumferential winding technique but also could be applied simply by additionallayer of woven mat or the like.
Filament winding is a technique in which a band of parallel rovings are brought to the mandrel Iying in a plane longitudinal to the mandrel.The mandrel is then rotated so that the band is drawn circumferentially around the mandrel. Relative movement is then provided between the band and the mandrel gradually longitudinally of the axis. The band thus is theoretically applied in a helical manner, but in practical terms some of the fibers may lie directly above previously laid fibers or may even move contrary to the longitudinal movement due to the tendency to fall back or to slip back and forthover one another. In some cases the helix angle can be increased. In the specification, therefore, the term "helically wound" is intended to refer to this WO 94/26501 ~ 1. 3 8 7 81 PCT/CA94/00206 type of filament winding and the term is intended to be synonymous with the term "circumferentially wound".
It is preferable that the structure include three layers including the first layer on the inner surface of the structure which is helically wound. The second layer is the longitudinal layer which is then applied on the outside surface of the first layer and surrounds the first layer. The third layer is again a helical layer applied around the first layer. It is preferable that the first and third layers constitute the inner and outer layers respectively to provide the required hoop strength for the structure to prevent transverse collapse of the tubular body in a buckling mode.
Preferably each of the layers decreases in thickness from the lower end of the pole to the upper end. In particular the central or second layer may decrease in thickness and certainly decreases in volume of fiber. This is achieved by the technique of terminating some of the fibers which extend from the lower end at a position intermediate the length of the pole so as to gradually reduce the number of fibers extending along the length of the pole from a lower end to the upper end. Some of the fibers extend the full length of the pole while others therefore are cut off or terminated at a predetermined position short of the upper end. It will of course be appreciated that, since the diameter of the pole decreases from the lower to the upper end, the volume of fibers applied longitudinally must decrease proportionally or the thickness of the layer will increase.
One embodiment of the invention will now be described in conjunction with the accompanying drawings in which:
Figure 1 is an isometric view of an electric power transmission line according to the present invention.
Figure 2 is side elevational view of a second embodiment of power transmission line according to the present invention.
Figure 3 is a vertical cross sectional view through a pole according to the present invention.
Figure 4 is a cross sectional view along the lines 4-4 of Figure 3.
WO 94/26501 2 ~ ~ 8 7 ~1 PCTICA94/00206 o Figure 5 is a cross sectional view similar to that of Figure 3 on a smaller scale showing the burial of the pole in the ground.
Figure 6 is a cross sectional view similar to that of Figure 4 showing a modified arrangement of the second layer including portions of increase thickness.
Figure 7 is a longitudinal cross sectional view through a further pole construction showing an alternative technique for forming the longitudinal fiber section.
Figure 8 is a cross sectional view along the lines 8-8 of Figure 7.
Figure 9 is a cross sectional view along the lines 9-9 of Figure 7.
Figure 10 is a cross sectional view along the lines 10-10 of Figure 7.
Figure 11 is a cross sectional through a pole of similar construction to that of Figure 7 showing a yet further arrangement for forming the longitudinal fiber-section.
An electricity power transmission line is indicated generally at 10 in Figure 1 and includes power cables 11 mounted on pole structures 12 and 13. In Figure 1 the pole structures 12 and 13 comprise composite pole structures including seperate poles 14 and 15 and a transverse coupling frame generally indicated at 16. In Figure 2 an alternative form of pole structure forthe transmission line is shown which includes a single pole 18 with three seperate arms 19, 20 and 21. Each of the poles 14, 15 and 18 is formed in the manner set forth hereinafter and is buried in the ground surface so as to stand vertically upwardly from the ground surface and supported by the ground.
The structure of the pole is shown in Figures 3, 4 and 5. Thus, as shown in Figure 5, the pole comprises a pole body 23 which is shaped as a frustum of circular cross section. Other cross sections, however can be used.
Thus the body tapers in outside dimension from an upper end 24 to a lower end 25 gradually increasing in diameter toward the lower end 25. Preferably, although not essentially the thickness of the body between an outside surface 26 and an inside surface 27 gradually increases from the upper end 24 to the lower end 25. This shape including the degree of taper of the body as a whole WO 94/26501 21~ 8 7 ~1 PCT/CA94/00206 .
and the degree of the taper of the thickness of the body can be carefuliy calculated to provide the maximum sL~engLh for the body. As one example, the dimensions of the pole may be 60 feet in length tapering from a lower diameter of the order of 18 to 24 inches to an upper diameter of the order of 8 to 10 inches. The thickness of the wall is of the order of 3/8 inch to 1 /2 inch. It will be appreciated that this thickness is relatively thin in comparison with the diameter. It is therefore possible that the thickness may also taper toward the upper end but this is not in any way essential.
A cap 28 is applied on the upper end 24 to provide a closure to prevent entry of water or other materials through the upper end. The cap as shown includes a plug portion 29 extending into the hollow interior of the pole body 23 together with a top portion extending over the hollow interior and outwardly to cover the annular upper end of the pole body.
In the embodiment shown in Figure 5, a lower part of the pole body is filled with a solid filler material 30 such as conc-eL~ or a foamed polymer and the like which extends from the lower end 25 to a height above the ground surface 31. Thus the lower end of the pole is buried into the ground to a conventional depth suitable to support the pole wholly by its engagement with the ground and the conc~ete or other filler material fills the area of the pole up to the ground surface and beyond the ground surface so that the pole is prevent from receiving water on the interior which could act in a freeze/thaw cycle to cause cracking of the pole body. Between the filler material and the inside surface of the pole body is provided a layer of sealant 32 which engages over the inside surface to a height of the solid filler material. The sealant material 32 also extends as indicated at 32A around the exposed lower end of the body 23 so as to prevent the entry of moisture into the interstices in the body and wicking of the moisture along the length of the body which would again cause cracking of the part in a freeze/thaw cycle.
Also shown in the embodiment of Figure 5, the hollow interior between the upper edge of the filler 30 and the underside of the cap 28 is filled with a lightweight foamed filler 33 which prevents further the entry of any materials into the hollow interior and which also provides some structural WO 94/26501 213 8 7 81 PCT/CA94/00206 ~
stability for the body 23. As is well known one process by which a tubular body can be broken is by transverse buckling collapse of the walls of the body thus allowing bending at the collapsed location. This transverse collapse is resisted by the foamed filler materials 30 and 33.
In an alternative arrangement a single filler material can extend along the full length of the body and this will generally be of a light weight foamed material which resists the penetration of water and also provides some structural strength against buckling. The sealant layer 32 may be provided only on the axial end face of the body at the lower end as indicated at 32A.
On the outside surface of the body extending from the lower end 25 to a height above the ground is provided an outer layer 34 which is applied on the outer surface 26. This outer layer is formed of a resin 35 and a particulate filler material 36. The resin 35 is selected to be of a type which is resistant to combustion so that fires at the ground level will not cause combustion of the body 23 due to the resistance of the outside layer 34 as well as to in part suitable weathering resistance properties to the outside surface of the pole. The height of the layer above the ground is selected to provide fire retardancy up to an expected height to which fire could reach in the circumstances of a brush fire or the like. The filler material 36 can be of sand, glass flakes or the like which becomes exposed at the surface of the resin.
This also acts as a fire retardant but also acts to reduce erosion or stripping of the resin at the surface due to soil movement in high winds and the like as wellas imparting a weathering resistant outer surface with respect to UV exposure and subsequent erosion.
The detailed structure of the body is shown in more detail in Figures 3 and 4. Thus the body is formed from a plurality of layers including the sealant layer 32, a first filament wound layer 37, a second longitudinal layer 38, a third filament wound layer 39, and the outer layer 34. In addition an optional wrapping layer 40 can be provided outside the second longitudinal layer 38.
Thus the structural sl,enyll~ of the body is formed from a composite of mainly the three layers 37, 38 and 39. Each of these layers ~ WO 94/26501 2 13 8 7 ~1 PCT/CA94/00206 varies in thickness so that the thickness of the layer gradually decreases from the lower end 25 to the upper end 24.
in the layer 37, the layer is formed from filament wound reinforcing fibers which are impregnated with resin material so as to form a layer of fiber reinforced plastics material. The filament wound fibers are wrapped around a longitudinal axis of the body generally by rotating a mandrel on which the body is formed about the axis 41. The fibers are laid generally circumferentially but with a slight helix angle only slightly differing from an angle directly at 90 to the axis 41. Thus it is intended that the fibers in thelayer 37 are generally circumferential in direction rather than having any significant longitudinal components. This layer thus provides circumferential hoop strength for the body. When required, the variation in thickness of the layers is obtained by reducing the number of wraps indicated at 42 and 43 in the layer 37 which thus gradually decreases along the length of the layer.
In the layer 38, there is provided an impregnating resin and a plurality of supporting fibers 44, 45 and 46 which are shown of course only schematically. In the layer 38 the fibers are intended to have as their major component of direction a direction essentially longitudinal of the part. Thus some of the fibers indicated schematically at 44 extend from the lower end 25 of the body wholly along the full length of the body to the upper end 24. The fibers 44 thus extend directly parallel to the axis 41 and lie in axial planes. Of course the fibers 44 as illustrated represent a series of fibers arranged at angularly spaced positions around the axis 41 within the layer 38.
As stated above, in order to maintain the thickness of the layer 38 constant or in order to reduce the thickness of the layer 38 from the lower end toward the upper end it is necessary to reduce the volume of fibers along the length of the pole body. This is achieved in that some of the fibers as indicated at 45, 46 commence at the lower end 25 but then terminate at positions 45A and 46A at spaced positions along the length of the layer. Again it will be appreciated that the fibers illustrated at 45 and 46 represent a whole series of fibers spaced angularly around the axis 41 all of which terminate at the positions as shown. This provides in effect a series of groups of fibers all WO 94/26501 2 ~ 3 8 7 8 1 ~ PCTICA94/00206 1 of which terminate at progressively group positions along the length of the body.
Turning now to Figure 4, the fibers of the layer 38 are formed generally of a first type of fiber but in four zones 38A spaced angularly aroundthe axis 41 a second type of fiber is blended with the first type. As shown schematically, there are four such zones of blended fibers arranged at the 12:00, 3:00, 6:00 and 9:OO positions. These positions correspond to directions longitudinal of and transverse to intended direction of the power cable. The main bulk of the fibers in the layer 38 are formed from glass as these are inexpensive and provide generally satisfactory structural strength.
However in the zones 38A fibers of a different type can be blended with the glass fibers to provide different strength/stretch characteristics. One problem with glass fibers is they tend to have a low modulus of elasticity so that theremay be in some cases a reduced dampening effect on transverse vibrations in the finished pole. This tendency can be improved by providing additional fibers of an increased elasticity in the zones 38A, bearing in mind that such fibers will be of significantly increased cost relative to the standard glass fibers.
In Figure 6 is shown a further modified arrangement in which the layer 38 is increased in thickness at four zones corresponding to the longitudinal and transverse positions of the power cable. At these zones the number of longitudinal fibers is significantly increased so as to define a lobe on the outside surface of the body generated by this additional longitudinal fibers.
In the embodiment shown there are four such lobes indicated at 38B. In an alternative arrangement only two such lobes may be provided either in the longitudinal or transverse positions in accordance with technical requirements to provide the desirable stiffness or resistance to bending.
The second layer 38 has an inner surface which is tapered, an outer surface which is also tapered and a thickness which varies. This layer cannot therefore be formed by pultrusion which of course requires a constant transverse cross section along the full length of the part. In addition the second layer is provided outside the inner layer which is already formed by the filament winding technique.
~ WO 94/26501 2 1~ 8 7 81 PCT/CA94/00206 The third filament wound layer 39 is formed on the outside of the second longitudinal layer 38 and again extends along the full length of the bodyand is formed by helically wound fibers as described in relation to the inner layer 37. The thickness of the third layer can be increased in the area of the outer layer 34 as shown in Figure 5 to provide an increased structural strength in that area and increased resistance to erosion. In addition the layer 39 has an increased thickness as indicated at 39A in a band at the top of the pole for receiving the transverse coupling members 16 or for receiving the support bars 19, 20, 21. The mounting arrangement for the coupling bars is not shown but could include a band clamped around the pole at the thickened band 39A and fastened thereto by a clamping action or by bolt and sleeve arrangement passing through the body 23.
In Figure 3 the outer layer 34 is shown to extend along the full length of the body. However the outer layer can be modified at the height shown in Figure 5 in the particulate reinforced material to a simply a resin layer or resin rich layer on the outside of the layer 39. Other coatings may be used such as epoxy, vinyl, polyester urethane, silicone simply to provide an attractive appearance and resistance to damage.
In Figure 3 is shown a modified technique for reinforcement of the internal structure of the body 23 and this comprises an elongate cable or rod 50 which carries a plurality of transverse discs 51 which are engaged against the inside surface 27. The rod 50 can be a complete longitudinal rod extending along the full length of the pole. Alternatively the rod can be formedin segments with each segment attached to the underside of one disc and the upper side of the next adjacent disc. Such an arrangement automatically spaces the discs at the required spacing along the length of the structure without the necessity of providing locating elements on the rod. These again therefore provide resistance to transverse collapse of the inside surface. In alternative arrangements the body can be completely hollow from the cap down to the solid insert 30 with the necessary structural strength being provided solely by the layers 37, 38 and 39. ~
W094/26501 213 8 ~ ~ ~ PCT/CA94/00206 ~
r The length of the pole is preferably greater than 60 feet. Up to this height, the cost of the composite materials is such that it is very difficult to compete with the very inexpensive wooden poles which are readily available.
However above this height the cost of wooden poles dramatically increases and in addition the increased cost of the composite material type pole provides sufficient advantages over the existing wooden poles to justify the increased cost. Shorter poles may be used in situations where the wooden poles are found to be a significant environment problem.
The layers can be formed by various techniques. In general the inside layer 37is formed on the outside surface of an existing mandrel which is subsequently intended to be removed from the structure. The inside layer is thus fully formed by a filament wrapping technique, as is well known, along the full length of the mandrel from the lower end 25 to the upper end 24 of the pole. The longitudinal layer 38is then formed by laying the fibers longitudinally on the already formed inner layer 37 and cutting the groups 45, 46 as required.
The fibers can be laid longitudinally by grasping all of the fibers at the lowerend just beyond the end of the body and the mandrel and then pulling the fibers longitudinally while cutting those fibers that need to be cut. The wrapping layer 40 can then be applied behind the fibers as they are pulled longitudinallyof the mandrel simply to hold the longitudinal fibers in place prior to the set~ing of the resin. After the longitudinal fibers are fully laid and wrapped so that they are held in place, the third layer 39 can be applied by rotating the mandrel carrying the layers 37,38 and 40 to apply the third structural layer. Setting ofthe resin can be effected in three seperate stages or alternatively the three layers can be applied before the resin is set by selecting suitable time constants for the resin or by actuating the resin by heat or other known techniques. In a particularly prefer,ed arrangement, the longitudinal fibers are applied by moving the mandrel carrying the inner layer 37 longitudinally of a wrapping station which applies fibers fully around the layer 37 as the mandrel moves longitudinally. Behind the station which applies the longitudinal fibers is provided a wrapping station which provides fibers of the wrapping layer 40 ~ WO 94/26501 213 8 7 81 PCT/CA94/00206 wrapped helically around the layer 38 to hold the fibers in place. Subsequently the layer 39 is applied by rotating the mandrel.
In a further alternative, the longitudinal fibers can be laid up on the outer surface of the layer 37 by forming the fibers into a blanket which is then wrapped around the outer surface of the layer 37 and held in place by a wrapping system defined in layer 40. The blanket may be carried by a sheet which is then removed before the wrapping layer 40 is applied.
While the inner filament wound layer 37 and the outer filament wound layer 39 may be formed of fibers which are wrapped with a very shallow helix angle that is close to a plane at right angles to the axis of the pole, in some cases some or all of the fibers may be wrapped with a larger helixangle. This increased helix angle can assist in transmitting loads around the layer to resist buckling forces.
Turning now to Figures 7 through 10, an alternative arrangement is shown for forming the longitudinal fiber layer indicated generally at 60. As previously described an inner layer 61 of helically wrapped fibers is provided on the inside surface of the layer 60 and in addition an outer layer 62 of helically wound fibers is applied on the outside surface of the longitudinal layer 60. Thefurther layers and reinforcement materials described herein before are omitted for convenience of illustration.
In the construction of Figures 7 through 10, the longitudinal fiber layer is formed by a plurality of pultruded strips formed of fiber reinforced resin material. As shown in the cross section of Figure 8, the strips 63, 64, 65 etc.
are formed into a stack having a width very much less than the circumference of the pole. Thus for example in a pole having an initial bottom diameter of 24 inches, so the circumference is approximately 80 inches, the stack will have a width W in the range 0.25 to 3.0 inches preferably of the order of 1.5 inches.
Each strip in the stack has a thickness in the range 0.030 to 0.25 inches and preferably of the order of 0.05 inches so that approximately twelve strips are necessary at the base of the pole to complete the full thickness of the layer asindicated at T. Each of the strips forming the single stack has the same width W. In this way the cross section of the stack is rectangular. As shown in WO 94/26501 213 8 7 ~ PCT/CA94/00206 Figure 7, the inner most one of the strips 63 extends along the full length of the pole and forms the full extent of the longitudinal layer. The strips 64, 65 etc.are of reduced length relative to the strip 63 so as to form a staggered arrangement in which an outer most one of the strips indicated at 66 terminates at an upper end 67. Each further strip inwardly of the outermost strip then terminates at an upper end of that strip with the upper ends being staggered along the length of the pole to gradually reduce the thickness of the longitudinal layer 60. In an aller"ali~e arrangement (not shown) the continuous strips along the full length of the pole can be arranged on the outside of the stack. In a further alternative continuous strips can be arranged on the inside and the outside to increase stability of the stack, with the shorter strips in between the inner and outer strips and therefore protected thereby. As the strips are thin, the discontinuities can be bridged without difficulty.
In order to prevent penetration of moisture between the stacks from causing damage, the spaces between the stacks can be filled with a foam such as a polyester foam which is compatible with the type of resin used with the fibers. One type of polyester foam can be arranged to effect foaming without curing so that the foamed but uncured material can be inserted into the spaces and covered with the outer wrapping layer of fibers and resin while any uncured foam is simply displaced by the wrapping layer or absorbed by it.
As shown in Figure 8, the stacks of strips are arranged at spaced positions around the periphery of the pole. As the diameter of the pole tapers inwardly, the spacing between the stacks gradually decreases. Thus the spacing at Figure 8 is indicated at S1 and the spacing in Figure 9 at a positionpartway up the pole is indicated at S2. At the top of the pole as indicated in Figure 10,the spacing is reduced effectively to zero so that the edges of the strip 63 are effectively in contact as indicated at 63A thus forming effectively a continuous layer around the full periphery of the pole at the top end of the pole.
The layers forming each stack are bonded together by suitable adhesive or resin material so as to form effectively an integral stack. In addition the inside surface of the layer 63 is bonded to the layer 61 and similarly the outside surface of the layer 66 is bonded to the outer layer 62.
~ WO 94/26!;01 2 i 3 8 7 81 PCT/CA94/00206 This forms the whole structure into an integral structure. The bonding can be effected using the resin material within which the fibers are embedded, with the time constance of the setting of the resin being arranged to effect the bonding during the manufacturing process.
The alternative arrangement shown in Figure 11 is very similar to that of Figures 7 through 10 except that the longitudinal layer is formed from aplurality of longitudinal elements equivalent to the stacks of Figures 7 through10. In this case, however, the longitudinal elements are formed in wedge shape so that a single element 70 tapers from a lower end 71 to an upper end 72 with that taper being gradual and continuous along the full length of the element. Such elements can be formed by cutting diagonally a pultruded bar of rectangular cross section. Thus the diagonal cutting forms two such elements one of which is then inverted so that the bottom end is the thicker end and the top end is the thinner end. The cross section of the pole as shown in Figure 11 will therefore be very similar to that shown in Fi3ures 8, 9 and 10 except that each longitudinal element 70 will not be formed from separate layers.
The layers of the stacks of Figure 7 and the individual elements of Figure 11 which are then cut to form the wedge shaped members are formed by pultrusion using conventional technique so that the reinforcing fibers of thelayers and elements are directly longitudinal.
- The layers thus defined above provide a totally unique structure for the composite fiber reinforced plastics material pole which cannot be formed by the conventional techniques of pultrusion, lay-up, filament winding orcentrifugal casting techniques but require the directly longitudinal fiber placement as explained herein before.
Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without departing from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.
Claims
CLAIMS:
(1) A support pole comprising a pole body which is shaped as a tapered, hollow frustum surrounding a straight longitudinal axis thus having across section which has a hollow interior and reduces in outside and inside dimensions from a lower end of the pole to an upper end of the pole body, the pole body being formed from a fiber reinforced plastics material, the pole body including a first layer which is reinforced by fibers wound helically of the axis and a second layer coaxial with a first layer which is reinforced by fibers extending substantially parallel to the axis.
(2) The support pole according to Claim 1 wherein at least some of the fibers of the second layer are continuous along the full length of the pole body.
(3) The support pole according to Claim 1 wherein the fibers of the second layer lie directly in axial planes.
(4) The support pole line according to Claim 1, 2 or 3 wherein the first layer comprises an inner layer of the hollow interior and wherein the second layer surrounds the first layer.
(5) The support pole according to Claim 4 including a third layer surrounding the first layer, the third layer being reinforced by at least some fibers wound helically of the axis.
(6) The support pole according to Claim 1, 2 or 3 including wrapping means around the second layer, the wrapping means being arranged to locate the longitudinal fibers.
(7) The support pole according to Claim 1, 2 or 3 including an additional layer defining an outer layer of the pole body.
(8) The support pole according to Claim 7 wherein the additional layer is arranged only over a part of the body extending from the lower end to an intermediate position along the length of the pole body.
(9) The support pole according to Claim 8 wherein the additional layer is formed from a plastics material which is fire resistant.
(10) The support pole according to Claim 7 wherein additional layer includes a particulate material resistant to abrasion.
(11) The support pole according to any preceding Claim wherein the total thickness of the layers from the outside dimension to the inside dimension reduces from the lower end to the top end of the pole body.
(12) The support pole according to Claim 11 wherein the thickness of each layer reduces from the lower end to the upper end of the pole body.
(13) The support pole according to Claim 1 wherein the second layer includes a plurality of groups of fibers, the fibers of one group being continuous along the full length of the pole body, the fibers of other groups extending from a lower end to an upper end of the fibers of the group located at a common group position along the length of the pole body, the group positions of the groups being spaced longitudinally of the pole body.
(14) The support pole according to any preceding Claim wherein the pole body is buried in the ground and wherein the pole includes an insert material extending from the lower end to a height above the ground surface.
(15) The support pole according to Claim 14 wherein the pole body includes a sealant material on the lower end and on the inside surface extending along the length of the insert.
(16) The support pole according to any preceding Claim wherein the pole body is filled with a filler material substantially along the full length thereof.
(17) The support pole according to any preceding Claim wherein the pole body includes a plurality of axially spaced transverse reinforcing members engaging the inside surface.
(18) The support pole according to Claim 5 wherein the third layer is of increased thickness to form bands on the outer surface of the pole body, the pole being buried in the ground up to a ground surface, a first thicker band being arranged on the pole body from the lower end to the ground surface and at least one further band being arranged adjacent the upper end of the pole body to form areas for attachment to transverse members for the pole.
(19) The support pole according to any preceding Claim wherein the longitudinal fibers of the second layer include glass fibers and a plurality of other fibers different from glass arranged in separate zones angularly spaced around the pole body.
(20) The support pole according to any preceding Claim wherein the second layer includes a plurality of zones at angularly spaced positions around the pole body in which zone the thickness of the second layer is increased.
(21) The support pole according to Claim 20 wherein the zones are aligned with the longitudinal and transverse directions of the transmission line.
(22) The support pole according to any preceding claim wherein the longitudinal fibers of the second layer comprise a plurality of separate longitudinally extending reinforcing members located at positions around the circumference of the pole body.
(23) The support pole according to Claim 22 wherein the separate elements are preformed prior to attachment to the first layer.
(24) The support pole according to Claim 22 wherein the seperate elements are of substantially constant width and have defined therebetween spaces at the lower end of the pole with those spaces tapering gradually inwardly toward the upper end of the pole.
(25) The support pole according to Claim 24 wherein separate elements are substantially in contact as side edges thereof at the upper end of the pole.
(26) The support pole according to any one of Claims 22 through 25 wherein each of the separate elements tapers in radial thickness from the lower end to the upper end.
(27) The support pole according to Claim 26 wherein each of the separate elements is formed from a plurality of laminated strips with a number of strips in the radial thickness at the lower end being greater than thenumber of strips in the radial thickness at the upper end.
(28) The support pole according to Claim 26 wherein the separate elements are formed by diagonally cutting a preformed pultruded bar of rectangular cross section.
(1) A support pole comprising a pole body which is shaped as a tapered, hollow frustum surrounding a straight longitudinal axis thus having across section which has a hollow interior and reduces in outside and inside dimensions from a lower end of the pole to an upper end of the pole body, the pole body being formed from a fiber reinforced plastics material, the pole body including a first layer which is reinforced by fibers wound helically of the axis and a second layer coaxial with a first layer which is reinforced by fibers extending substantially parallel to the axis.
(2) The support pole according to Claim 1 wherein at least some of the fibers of the second layer are continuous along the full length of the pole body.
(3) The support pole according to Claim 1 wherein the fibers of the second layer lie directly in axial planes.
(4) The support pole line according to Claim 1, 2 or 3 wherein the first layer comprises an inner layer of the hollow interior and wherein the second layer surrounds the first layer.
(5) The support pole according to Claim 4 including a third layer surrounding the first layer, the third layer being reinforced by at least some fibers wound helically of the axis.
(6) The support pole according to Claim 1, 2 or 3 including wrapping means around the second layer, the wrapping means being arranged to locate the longitudinal fibers.
(7) The support pole according to Claim 1, 2 or 3 including an additional layer defining an outer layer of the pole body.
(8) The support pole according to Claim 7 wherein the additional layer is arranged only over a part of the body extending from the lower end to an intermediate position along the length of the pole body.
(9) The support pole according to Claim 8 wherein the additional layer is formed from a plastics material which is fire resistant.
(10) The support pole according to Claim 7 wherein additional layer includes a particulate material resistant to abrasion.
(11) The support pole according to any preceding Claim wherein the total thickness of the layers from the outside dimension to the inside dimension reduces from the lower end to the top end of the pole body.
(12) The support pole according to Claim 11 wherein the thickness of each layer reduces from the lower end to the upper end of the pole body.
(13) The support pole according to Claim 1 wherein the second layer includes a plurality of groups of fibers, the fibers of one group being continuous along the full length of the pole body, the fibers of other groups extending from a lower end to an upper end of the fibers of the group located at a common group position along the length of the pole body, the group positions of the groups being spaced longitudinally of the pole body.
(14) The support pole according to any preceding Claim wherein the pole body is buried in the ground and wherein the pole includes an insert material extending from the lower end to a height above the ground surface.
(15) The support pole according to Claim 14 wherein the pole body includes a sealant material on the lower end and on the inside surface extending along the length of the insert.
(16) The support pole according to any preceding Claim wherein the pole body is filled with a filler material substantially along the full length thereof.
(17) The support pole according to any preceding Claim wherein the pole body includes a plurality of axially spaced transverse reinforcing members engaging the inside surface.
(18) The support pole according to Claim 5 wherein the third layer is of increased thickness to form bands on the outer surface of the pole body, the pole being buried in the ground up to a ground surface, a first thicker band being arranged on the pole body from the lower end to the ground surface and at least one further band being arranged adjacent the upper end of the pole body to form areas for attachment to transverse members for the pole.
(19) The support pole according to any preceding Claim wherein the longitudinal fibers of the second layer include glass fibers and a plurality of other fibers different from glass arranged in separate zones angularly spaced around the pole body.
(20) The support pole according to any preceding Claim wherein the second layer includes a plurality of zones at angularly spaced positions around the pole body in which zone the thickness of the second layer is increased.
(21) The support pole according to Claim 20 wherein the zones are aligned with the longitudinal and transverse directions of the transmission line.
(22) The support pole according to any preceding claim wherein the longitudinal fibers of the second layer comprise a plurality of separate longitudinally extending reinforcing members located at positions around the circumference of the pole body.
(23) The support pole according to Claim 22 wherein the separate elements are preformed prior to attachment to the first layer.
(24) The support pole according to Claim 22 wherein the seperate elements are of substantially constant width and have defined therebetween spaces at the lower end of the pole with those spaces tapering gradually inwardly toward the upper end of the pole.
(25) The support pole according to Claim 24 wherein separate elements are substantially in contact as side edges thereof at the upper end of the pole.
(26) The support pole according to any one of Claims 22 through 25 wherein each of the separate elements tapers in radial thickness from the lower end to the upper end.
(27) The support pole according to Claim 26 wherein each of the separate elements is formed from a plurality of laminated strips with a number of strips in the radial thickness at the lower end being greater than thenumber of strips in the radial thickness at the upper end.
(28) The support pole according to Claim 26 wherein the separate elements are formed by diagonally cutting a preformed pultruded bar of rectangular cross section.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US5872093A | 1993-05-10 | 1993-05-10 | |
| US058,720 | 1993-05-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2138781A1 true CA2138781A1 (en) | 1994-11-24 |
Family
ID=22018513
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2138781 Abandoned CA2138781A1 (en) | 1993-05-10 | 1994-05-05 | Support pole for electricity power transmission line |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU6561594A (en) |
| CA (1) | CA2138781A1 (en) |
| WO (1) | WO1994026501A1 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103883152A (en) * | 2012-12-21 | 2014-06-25 | 河南省电力勘测设计院 | Novel cable net film structure, inner barrel and smoke tower integrated structural system |
| CN103938911A (en) * | 2014-05-13 | 2014-07-23 | 江苏神马电力股份有限公司 | Composite tower head and lattice type power transmission tower with composite tower head |
| CN104005592A (en) * | 2014-06-05 | 2014-08-27 | 国家电网公司 | 110 kV lattice type composite material tower |
| WO2022076184A1 (en) * | 2020-10-09 | 2022-04-14 | Valmont Industries, Inc. | Improved distribution pole and method of fireproof distribution pole installation |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8322105B2 (en) * | 2006-05-18 | 2012-12-04 | Duratel, Llc | Pultruded utility support structures |
| GB2448363A (en) * | 2007-04-13 | 2008-10-15 | 3M Innovative Properties Co | Tubular support of composite material |
| GB2448362B (en) * | 2007-04-13 | 2012-02-29 | Frangible Safety Posts Ltd | Sign post comprising composite material |
| FR2957844B1 (en) * | 2010-03-26 | 2012-05-18 | Messier Dowty Sa | METHOD FOR MANUFACTURING A MECHANICAL MEMBER IN COMPOSITE MATERIAL HAVING INCREASED MECHANICAL TENSION-COMPRESSION AND BENDING |
| AU2011242786A1 (en) * | 2010-04-20 | 2012-11-15 | Conett, Inc. | Composite pole and method for making the same |
| US8474221B1 (en) | 2012-01-20 | 2013-07-02 | Trident Industries, LLC | Telescoping fiberglass utility pole |
| DK3004492T3 (en) * | 2013-05-29 | 2017-07-17 | Jerol Ind Ab | A BODY STRUCTURE |
| EP3741931A1 (en) * | 2019-05-20 | 2020-11-25 | ABB Power Grids Switzerland AG | Post and method of providing a post |
| CN112727223A (en) * | 2021-01-05 | 2021-04-30 | 王茂良 | Composite material conical tube easy to assemble |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB928348A (en) * | 1960-12-01 | 1963-06-12 | A C Ford Ltd | Improvements relating to columns for supporting lamps for street lighting purposes |
| US3574104A (en) * | 1968-01-24 | 1971-04-06 | Plastigage Corp | Glass fiber constructional member |
| US4172175A (en) * | 1978-02-17 | 1979-10-23 | Tillotson-Pearson, Inc. | Pole construction |
| FI873285A (en) * | 1987-07-28 | 1989-01-29 | Nettec Ab Oy | FIBERARMERAT ROERELEMENT OCH FOERFARANDE FOER DESS TILLVERKNING. |
-
1994
- 1994-05-05 CA CA 2138781 patent/CA2138781A1/en not_active Abandoned
- 1994-05-05 WO PCT/CA1994/000206 patent/WO1994026501A1/en active Application Filing
- 1994-05-05 AU AU65615/94A patent/AU6561594A/en not_active Abandoned
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103883152A (en) * | 2012-12-21 | 2014-06-25 | 河南省电力勘测设计院 | Novel cable net film structure, inner barrel and smoke tower integrated structural system |
| CN103883152B (en) * | 2012-12-21 | 2016-05-25 | 河南省电力勘测设计院 | A kind of novel rope net membrane structure inner core cigarette tower combined structure system |
| CN103938911A (en) * | 2014-05-13 | 2014-07-23 | 江苏神马电力股份有限公司 | Composite tower head and lattice type power transmission tower with composite tower head |
| CN104005592A (en) * | 2014-06-05 | 2014-08-27 | 国家电网公司 | 110 kV lattice type composite material tower |
| CN104005592B (en) * | 2014-06-05 | 2016-08-17 | 国家电网公司 | A kind of 110kV lattice composite material pole tower |
| WO2022076184A1 (en) * | 2020-10-09 | 2022-04-14 | Valmont Industries, Inc. | Improved distribution pole and method of fireproof distribution pole installation |
Also Published As
| Publication number | Publication date |
|---|---|
| AU6561594A (en) | 1994-12-12 |
| WO1994026501A1 (en) | 1994-11-24 |
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