TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION

The present invention relates generally to tapered composite towers or utility poles manufactured from reinforced resin materials such as fiber reinforced plastic (FRP), and, more particularly, to a method and an apparatus for producing such products.

BACKGROUND OF THE INVENTION

Tapered towers and utility poles made from reinforced resin materials are particularly useful in supporting windmills for electric generation and electrical transmission lines and cabling. Methods for making composite utility poles of cylindrical shape are disclosed in, for example, U.S. Patents 4, 081, 302 Drostholm et al. and 4, 082, 597 Drostholm. A method and apparatus for producing tapered composite utility poles is disclosed in U.S. Patent 5, 492,579 to Hosford et al.

The present invention relates to a new and improved apparatus and method for making tapered towers or utility poles of desired length from reinforced resin materials in a continuous inline production process. One piece poles produced in this manner, advantageously, do not have to be joined and fabricated at the installation site. Further, since the resulting towers or utility poles are of continuous integral construction, they are stronger and more durable and provide a longer service life.

SUMMARY OF THE INVENTION

In accordance with the purposes of the present invention as described herein, an apparatus is provided for producing a tubular product, such as a tower or utility pole, from reinforced resin materials. The apparatus comprises a mandrel including a series of endless conveyors that are radially arranged about and radially displaceable with respect to a centerline of the mandrel. The apparatus further includes an applicator for applying reinforced resin material over the series of endless conveyors. In addition, the apparatus includes a shifter for radially shifting the series of endless conveyors toward or away from the centerline as the reinforced resin material supported thereon is moved along the continuous conveyors. More specifically describing the invention, the series of endless conveyors have a first end and a second end and those conveyors diverge from the centerline from the first end to the second end. Typically the series of endless conveyors diverge from the centerline at an angle of between about 0.5 and about 5 degrees. Most typically, the angle of divergence is between about 2.5 and about 3.0 degrees. The apparatus further includes a continuous band that is helically wound over and supported by the series of endless conveyors, a feeder that feeds the continuous band onto to the first end of the series of endless conveyors and a remover that removes the continuous band from the second end of the series of endless conveyors.

In accordance with an additional aspect of the present invention, a method is provided for producing a tubular product, such as a tower or utility pole, using a mandrel, having a series of endless conveyors. Those endless conveyors are radially arranged about and radially displaceable with respect to a centerline C of the mandrel. Further, the series of endless conveyors has a first end and a second end and those conveyors diverge from the centerline C, from the first end to the second end. The method comprises the steps of: (a) applying reinforced resin material over the series of endless conveyors; (b) at least partially curing the reinforced resin material; and (c) moving the series of endless conveyors radially toward the center line C so that the reinforced resin material is supported over the series of endless conveyors at a substantially constantly, tapering radius of curvature from the first end to the second end of the series of endless conveyors.

In one possible embodiment, the method includes the steps of winding a continuous band onto the first end of the series of endless conveyors and removing the continuous band from the second end of the series of endless conveyors. In this embodiment, the reinforced resin material is applied to the continuous band over the series of endless conveyors. In another possible embodiment, the method includes the step of winding a thermaplastic ribbon layer over the series of endless conveyors. In this embodiment, the reinforced resin material is applied to the ribbon layer over the series of endless conveyors.

In addition, the method includes using a reinforcing fiber for the reinforced resin material selected from a group consisting of glass fiber, natural fiber, carbon/graphite fiber, aramid fiber, basalt fiber, and mixtures thereof. Still further, the method includes using a matrix material for the reinforced resin material, selected from a group consisting of a thermoset resin like unsaturated polyester, vinylester, polyurethanes and epoxy resin and mixtures thereof, or a thermoplastic resin like polypropylene, polyamide or polyester (PET / PBT) and mixtures thereof.

In accordance with yet another aspect of the present invention, a one-piece tapered tubular product of continuous integral construction is made using the current method.

In the following description there is shown and described several different embodiments of the invention, simply by way of illustration of some of the modes best suited to carry out the invention. As it will be realized, the invention is capable of other different embodiments and its several details are capable of modification in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive.

BREIF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated herein and forming a part of the specification, illustrate several aspects of the present invention and together with the description serve to explain certain principles of the invention. In the drawings:

Figure 1 is a partially schematical and perspective view of one possible apparatus constructed in accordance with the teachings of the present invention;

Figure 2 is a schematical and elevational view illustrating the radially arrayed endless conveyors and centerline C of the mandrel as well as the radial axis along which the individual endless conveyors are moved or displaced during the forming of the tubular product;

Figure 3 is a schematical side elevation view illustrating one continuous conveyor and the shifter for moving that continuous conveyor radially with respect to the centerline of the mandrel;

Figure 4 is a schematical block diagram of the control circuit of the apparatus; and

Figure 5 is a perspective view of a tapered tubular product in the form of a utility pole produced using the method of the present invention. Reference will now be made in detail to the present preferred embodiment of the invention, an example which is illustrated in the accompanying drawing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Reference is now made to Figures 1 and 2 generally and schematically illustrating the apparatus 10 of the present invention for producing a tapering tubular product from reinforced resin materials. The apparatus 10 includes a mandrel, generally designated by reference numeral 12 that comprises a continuous band 14 that is helically wound over and supported by a series of endless conveyors, generally designated by reference numerals 16. In the illustrated embodiment eight individual conveyors 18a-18h comprise the series of endless conveyors 16. The conveyors 18a-18h are radially arranged about a centerline C of the mandrel 12, and together define a conveyor pathway of truncated cone shape. While eight conveyors 18a-18h are illustrated, it should be appreciated that a greater or lesser number may be used depending on the circumference of the final product to be produced and/or the particular application.

A feeder mechanism, schematically illustrated at 20, feeds the continuous band 14 onto the series of endless conveyors 16 at a first end thereof. A remover mechanism 22 (also schematically illustrated in Figure 1) removes the continuous band 14 from the series of endless conveyors 16 at a second end thereof. Such feeder and remover mechanisms are well known to those skilled in the art.

As best illustrated in Figure 1, the helical winding of the continuous band 14 onto the series of endless conveyors 16, serves to form an uninterrupted surface 24 for receiving and holding reinforced resin material. More specifically, an applicator, generally designated by reference numeral 26, applies reinforced resin material onto the continuous band 14 while that band is supported on the series of endless conveyors 16. As illustrated in Figure 1 , the applicator 26 may include, for example, feed chutes 27 and 31 for delivering reinforced resin material to the support surface 24 of the continuous band 14. In the illustrated embodiment the resin material may comprise chopped glass fiber, chopped natural fiber, chopped carbon fiber, and other filler material such as clay, foam particles, wood particles and mixtures thereof. In an alternative embodiment, the reinforced resin material may be fed onto the support surface 24 of the continuous band 14 in layers of fabric or mat comprising chopped reinforcement fibers, roving of fibers, direct roving of fibers, unwoven fibers, directional fibers, direct chopped woven reinforcement fibers, and mixtures thereof. The reinforced resin material incorporates a matrix material selected from a group consisting of thermoset resin like unsaturated polyester, vinylester, polyurethanes and epoxy resin or thermoplastic resin like polypropylene, polyamide or polyester (PET / PBT) and mixtures thereof. Chopped fibers typically have a length of 10mm to more than 500mm, and, more typically 25 to 100mm (1 to 4 inch).

The reinforced resin material is applied to the support surface 24 of the continuous band 14 in one or more layers of fabric, mat, or even direct chopped roving. A heating mechanism, generally designated by reference numeral 28, is provided for at least partially curing the reinforced resin material layers 30 deposited on the support surface 24 of the continuous band 14. As illustrated in Figure 1, the heater 28 comprises a hot air source 32 that provides a stream of hot air to the curing hoods 34, by means of ducts 36, 38, 40, and a curing oven 48.

As noted above, the series of endless conveyors 16 comprises eight conveyors 18a-18h. As best illustrated in Figures 1, 2, and 3, the conveyors 18a-18h are radially arranged about the center line C of the mandrel 12. As should be further appreciated, the series of endless conveyors 16 diverge from the centerline C as they extend from the first end 42 to the second end 44. The angle of divergence from the centerline C is typically from between about 0.5 to about 5.0 degrees and, more typically, between 2.5 and about 3.0 degrees. Because the series of conveyors 16 diverges from the centerline C from the first end 42 to the second end 44, the conveyors 18a-18h effectively form a conveyor pathway of truncated cone shape that supports and allows the formation of a tapered, tubular product.

A shifter mechanism 50 functions to radially shift the series of endless conveyors 16 toward or away from the centerline C during production of the tapered tubular product 52 (see Figure 5). As best illustrated in Figures 1 and 2, the series of endless conveyors 16 are supported on a cantilevered box beam 54 held by the upright stanchion 56. The continuous band 14 passes through the open space or lumen of the box beam 54 as it moves between the remover mechanism 22 and the feeder mechanism 20 (note action arrows).

Each of the conveyors 18a-18h comprises a frame 58 holding a series of freely rotating rollers or pulleys 60 that support a continuous belt such as an endless ball belt 62, such as described in more detail in U.S. Patent 3, 464,879 to Poulsen. Each conveyor 18a-18h also includes a drive motor 63 (see also Figure 4). Actuators 64 connect the frame 58 of each of the conveyors 18a-18h to the hollow support 54 such as the tubular support illustrated in Figure 1 or the multisided box beam illustrated in Figure 3. By extending the actuators 64, the individual conveyors 18a-18h are moved away from the box beam 54. In contrast, the actuator 64 are retracted in order to move the conveyors 18a-18h toward the box beam 54. In this way, the conveyors 18a-18h are moved in unison toward or away from the centerline C of the mandrel 12.

The method of producing a tubular product 52 from reinforced resin material utilizing that apparatus will now be described in detail. The method may be generally described as comprising the steps of : (a) winding the continuous band 14 onto the first end 42 of the series of endless conveyors 16; (b) applying reinforced resin material onto the continuous band 14 while supported over the series of the endless conveyors 16; (c) at least partially curing the reinforced resin material (note layers 30) while the reinforced resin material is supported on the continuous band 14; and (d) moving the series of continuous conveyors 16 radially toward the centerline C of the mandrel 12 so that the continuous band 14 is supported on the series of endless conveyors at a substantially constant radius of curvature as the continuous band moves from the first end 42 toward the second end 44 of the series of endless conveyors.

More specifically, the continuous 14 is helically wound onto the first end 42 of the series of endless conveyors 16 by the feeder mechanism 20. The reinforced resin material is then applied in layers 30 onto the support surface 24 of the continuous band 14 by means of the applicator 26. The reinforced resin material layers 30 are at least partially cured while being supported on the continuous band 14 by means of the heater mechanism 28. The series of endless conveyors 16 are gradually moved radially toward the centerline C by means of the actuators 64 so that the continuous band 14 is supported on the series of endless conveyors 16 at a substantially constantly tapering radius of curvature as the continuous band is moved along the series of continuous conveyors from the first end 42 toward the second end 44 by means of the actuator 64.

Here it should be appreciated that the conveyors 18a-18h are moved inwardly toward the center line C at a rate that matches the movement of the continuous band 14 along the series of endless conveyors 16 from the first end 42 to the second end 44. In this way, each portion of the continuous band 14 is wound onto, rides along and is unwound from the series of continuous conveyors at a constantly tapering radius of curvature, determined by the angle of divergence of the individual conveyors 18a-18h from the centerline C. As illustrated in Figure 4 a controller 100, such as a dedicated microcontroller, is connected to the conveyor drive motors 63 and the actuators 64 in order to control and coordinate their operation and allow the formation of the tapered tubular product. The controller 100 includes an operator interface 102, such as a keypad or keyboard, to allow the operator to set various parameters such as the starting and ending circumferences of the tapered tubular product as well as the angle of divergence.

In an alternative embodiment of the present invention, the mandrel 12 does not include a continuous band 14. Instead, the mandrel just comprises the series of endless conveyors 16. In this embodiment, the continuous band 14 is replaced by a thermaplastic ribbon layer that is helically wound directly over the series of endless conveyors 16 and actually forms the innermost layer of the final tubular product 52.

In summary, numerous benefits result from employing the concepts of the present invention. By simultaneous coordinated axial and inward radial movements of the series of endless conveyors 18a- 18b it is possible to continuously form a tapered tubular product 52. The resulting one-piece product 52 is characterized by continuous integral construction and is stronger and more durable than the multi-piece products of the prior art.

The foregoing description of the preferred embodiments of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variation are possible in light of the above teachings. The embodiments were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such medications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled. The drawings and preferred embodiments do not and are not intended to limit the ordinary meaning of the claims in their fair and broad interpretation in any way.