CENTRIFUGALLY CAST POLE AND METHOD

Abstract

Herein disclosed is a centrifugally cast pole having a substantially uniform wall thickness along the long axis of the pole. During centrifugal casting, molten metal is poured inside a rotating, tapered mold. As chilled liquid is poured over the outside of the rotating mold, the metal forms, or paints, to the contour of the mold interior creating a metal pole. By precisely controlling casting gyrations such as the spin, travel, pitch, and yaw of the rotating mold and the calibration and physical mechanisms of the casting machine, hollow, tapered, tubular metal poles are produced with previously unknown uniformity of wall thickness. The controlling principles, designs, and mechanisms of this centrifugal casting method enable wall uniformity to extremely high tolerances. By extension, the ability to precisely control the metal volume painted inside the mold allows, as a design choice, wall thickness variation in any embodiment if so desired.

Claims

1. A hollow, tapered, cylindrical utility pole laving an outer diameter that varies along a length of the member, comprising: a tapered, seamless, unitary cylindrical wall made of a metallic material via centrifugal casting, wherein a first portion of the tapered cylindrical all has a first thickness, wherein a second portion of the tapered cylindrical wall has a second thickness that is different from the first thickness, wherein the first thickness of the tapered cylindrical wall is substantially constant along a majority of the length of the cylindrical wall, and wherein an interior surface of a large diameter end of the tapered cylindrical wall has a shape and dimensions that would allow an external surface of a small diameter end of a second hollow, tapered, cylindrical utility pole to be inserted into the large diameter end of the tapered cylindrical wall; and a running ring also formed by the centrifugal casting and comprising a circular or ring-shaped flange that extends radially outward from an exterior side of the large diameter end of the tapered cylindrical wall, wherein the running ring is configured such that when the tapered, cylindrical utility pole is inserted into a cylindrical pipe having a pipe bell at one end, the flange has a sufficiently small diameter such that the flange will clear the pipe bell throat and a sufficiently large diameter such that the flange will engage the bell land so that as the cylindrical pipe is rolled along an annealing furnace, the tapered, cylindrical utility pole will remain inside the cylindrical pipe.

2. The hollow, tapered cylindrical utility pole of claim 1, wherein an interior diameter of the cylindrical wall narrows along the length of the cylindrical wall.

3. The hollow, tapered cylindrical utility pole of claim 1, wherein the first thickness of the first portion of the tapered, cylindrical wall is substantially uniform along the length of the first portion, and wherein the second thickness of the second portion of the tapered, cylindrical wall is substantially uniform along the length of the second portion.

4. The hollow, tapered cylindrical utility pole of claim 1, further comprising an access aperture that extends through the tapered, cylindrical wall adjacent the large diameter end of the tapered, cylindrical wall.

5. The hollow, tapered cylindrical utility pole of claim 1, wherein the access aperture is generally rectangular in shape.

6. The hollow, tapered cylindrical pole of claim 1, wherein the tapered, seamless, unitary cylindrical wall is formed via a centrifugal casting process in which molten metallic casting material is poured into a rotating mold while the rotating mold is translated, and in which at least one of a pouring rate of the molten metallic casting material, a rotational speed of the rotating mold and a translation speed of the rotating mold is varied during the casting operation such that the first thickness of the tapered cylindrical wall is substantially constant along a majority of the length of the cylindrical wall.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The foregoing and other objects, features, and advantages of the present invention will be apparent from the following more particular description of preferred embodiments as illustrated in the accompanying drawings in which reference characters refer to the same parts throughout the various views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

[0026] FIG. 1 is a side view of an embodiment of the invention showing the invention in a direct burial configuration.

[0027] FIG. 2 is a side view of the embodiment of FIG. 1 showing the invention in a flanged, based or foundation-mounted configuration.

[0028] FIG. 3 is a side view of the invention, partial sectioned, showing the slip joint design of the invention used for extended height.

[0029] FIG. 4 is a diagrammatic view of a typical centrifugal casting machine being used to cast an embodiment of the invention. Also shown, in partial longitudinal section is the tapered mold.

[0030] FIG. 5 illustrates the use of the running ring and the third rail being used to control the tapered pole as it rolls through an annealing furnace.

[0031] FIG. 6 shows the effective use of a dimpled surface to create turbulence, thereby reducing wind loading on the pole during high wind conditions.

[0032] FIG. 7 shows the procedure required to produce a long tapered mold, which is machined inside.

DETAILED DESCRIPTION OF THE PREFERRED INVENTION

[0033] FIG. 1 shows a hollow, centrifugally cast, utility pole 1 in a direct burial configuration according to an embodiment of the invention. FIG. 2 shows the invention in a pedestal or foundation-mounted configuration according to a second embodiment of the invention. The pole 1 of FIGS. 1 and 2 has been centrifugally cast in a manner which imparts a tapered shape to the external linear dimensions of the pole 1 from pole butt 2 to pole top 3 as shown. The tapered shape of the pole 1 gives the pole 1 added strength and also saves raw materials during the casting operation. The embodiments of FIGS. 1 and 2 further comprise a pole cap 4 and pre-drilled or field modified holes 5 for attachment of typical utility pole hardware and fixtures. Also shown in the embodiment of FIG. 1 is an access panel 6. Said panel 6 is located near the bottom interior or core 7 of the pole 1 in situations where internal hardware such as cables or wires have been installed within said hollow core 7. The centrifugal casting of the tapered pole 1 provides for the controlled wall thickness 8 along the entire length of the pole 1 whereby the wall thickness imparted to the pole 1 is controlled by design from pole top 3 to pole butt 2. This controlled wall thickness 8 provides greater design flexibility and strength to the pole 1.

[0034] FIG. 2 shows the pole 1 with a flange 9 at its butt 2 to enable the pole 1 to be mounted and secured to a foundation 10 or other pedestal-type apparatus. In this embodiment, the pole 1 is shown secured to the foundation 10 by a plurality of bolts 11 and nuts 12.

[0035] FIG. 3 shows the press-fit, slip-joint 13 configuration of the invention used to interconnect two or more cast pole 1 sections for extended height. The slip-joint 13 comprises a tapered, centrifugally cast, utility pole 1, according to the invention, wherein the internal core 7 diameter of the pole 1, beginning at the butt 2 of the pole 1 and extending internally linearly along a portion of the length of the pole 1, has been cast to have internal dimensions which allow the butt 2 of the pole 1 to slidably engage the top portion 3A of another centrifugally cast tapered pole 1A. Such interconnection provides for virtually unlimited extensions of pole 1 height.

[0036] FIG. 4 shows a typical centrifugal casting machine 14 being used to cast an embodiment of the invention. An internally tapered mold 15 is similar to conventional centrifugal casting molds with the exception of the internal linear dimensions of the mold 15 as shown in the longitudinal cross-section of the mold 15 is generally circular in form, however, the internal surface of the mold 15 could be modified to produce tapered poles having multisided dimensions such as poles with generally square or polygonal cross-sections. In the preferred embodiment of pole 1, an internally tapered chill-type mold 15, is used to impart a tapered external shape to the pole 1. Depending on the particular application and strength required of the pole 1, the overall wall thickness 8 (FIGS. 1 and 2) of the pole 1 may be varied during the casting operation by the pouring rate of material 16 allowed to enter the centrifugal casting mold 15 and by varying the RPM of the motor 17 also by the travel speed of the machine 18.

[0037] Also shown in FIG. 4 is a core mold 19 used to form the slip-joint 13 (FIG. 3) of the invention during the centrifugal casting process. When desired, said core mold 19 is inserted into the mold 15 at the butt 2 (FIGS. 1 and 2) of the pole 1 being centrifugally cast. When present during the centrifugal casting operation, the core mold 19 causes the core 7 (FIGS. 1 and 2) diameter of the cast pole 1 to be uniformly controlled along the length of said core mold 19. The core 7 (FIGS. 1 and 2) diameter formed by the use of said core mold 19 during the centrifugal casting process is sufficient to enable the butt 2 (FIGS. 1 and 2) of the pole 1 after casting to slidably engage the top portion 3A (FIG. 3) of another centrifugally cast pole 1A (FIG. 3).

[0038] FIG. 5 shows tapered pole 1 as it is pushed through the annealing furnace by pusher chains 20 and 21 along running rails 22, 23 and 24. As tapered pole 1 begins to travels in a circular path along running rails 22, 23 and 24, running ring 25 engages the third running rail 24, thereby allowing the tapered pole 1 to run essentially straight through an annealing furnace. The running ring 25 also allows for tapered pole 1 to be inserted into a conventional round pipe and carried thru an annealing furnace.

[0039] FIG. 6 shows texture (pimples) 26, which are cast into the surface of the pole's exterior during the manufacturing process. These pimples 26 are effective in reducing wind resistance on the face of the pole.

[0040] FIG. 7 illustrates one method of producing a tapered mold 15. The tapered mold 15 is made by matching various short tapered tubes 27, 28, 29, and 30 that have been machined prior to being welded into one long section, eliminating the need to bore long tapered I.D. holes.

[0041] While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various alterations in form, detail and construction may be made therein without departing from the spirit and scope of the invention.