US 3270480 A
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Description (OCR text may contain errors)
Sept. 6, 1966 w. BEECKER 3,270,480
TAPERED SECTIONAL SUPPORT POLE Original Filed May 29, 1962 INVENTOR. WILL/AM 8556/1157? ATTORNEY United States Patent 3,270,480 TAPERED SECTIONAL SUPPORT POLE William Beecher, P.O. Box 735, Lansdale, Pa. Continuation of application Ser. No. 198,679, May 29, 1962. This application Apr. 7, 1965, Ser. No. 448,562 Claims. (Cl. 52726) This application is a continuation of my copending application Serial No. 198,679 filed on May 29, 1962, now abandoned.
This invention relates to a tapered sectional support pole which is stronger and easier to manufacture than those proposed heretofore.
The individual sections of the tapered sectional poles proposed heretofore were not provided with a uniform taper and were formed from a sheet having side edges in overlapping relation and locked together by a tongue and recess arrangement. As a result of the non-uniform taper of the sections, annular stress forces developed which started in the weakest part of the section and causes the tongue and recess lock to spread apart. The tongue and recess joint on the individual sections required the sections to be assembled together in a particular relationship so that the joint or seam was disposed in the neutral area of the working load direction, that is 90 degrees with respect thereto.
The particular relationship between the seams or joints on the various sections presented a bottleneck in assembly of the pole. Production bottlenecks in connection with producing the various sections resulted since the smaller diameter sections tended to become boat shaped which also hampered the assembly of the pole. Due to the tensile strength of the tongue and recess lock, high strength and high carbon steels were required. Notwithstanding the high carbon steels used, the seam only had a tensile strength of approximately fifty percent to fifty-nine percent of the tensile strength of the basic material.
The poles assembled in accordance with the proposal set forth heretofore do not have the various sections overlapped for a sufficient distance. For example, it has been proposed heretofore that the various sections overlap each other for a distance corresponding to the largest diameter of the overlapped sections. Heretofore, those associated with the prior art failed to take into consideration a bulging factor which must be multiplied by the working load. Since the various sections do not have a uniform taper, a uniform overlap between the various sections was not provided for. Hence, the pole did not have an overall uniform strength.
, In order to utilize all the material in a pole to its full value, it is necessary to design a pole so that the sectional moduli throughout the pole length increases in the same proportion as the bending moment. In a tubular steel pole, this ideal condition could be theoretically achieved in two different Ways. Firstly, we could gradually increase the pole diameter while maintaining a constant wall thickness. This would result in a pole simulating the shape of the Eiffel Tower. Secondly, we could maintain a constant diameter and increase the wall thickness to obtain the necessary sectional moduli.
From a production standpoint, both of these designs are impractical. The present invention is directed to a uniformly stressed pole which is achieved by a combination of these two concepts. In the sectional pole of the present invention, the free edges of the various sections are welded together with a butt-joint in a manner so that the sections have a uniform thickness. Further, the various sections are provided with a taper which is uniform throughout the entire length of the pole and the wall thickness of the various sections decreases in the direction from the larger diameter portion of the pole to smaller diameter portion of the pole. The linear conicity of the 3,270,480 Patented Sept. 6, 1966 ice pole of the present invention results in an overall uniform snug fit between the overlapping sections thereby providing a uniform overall strength for the pole which approximates ninety-five percent of the tensile strength of the basic material from which the pole is constructed.
The pole of the present invention may be made from any one of a wide variety of materials in a more rapid manner than those proposed heretofore. The poles of the present invention have forty-five percent more strength in compression than those proposed heretofore and have a uniform even strength in any direction. The poles of the present invention may be produced more rapidly and assembled at the site of the pole in a more rapid manner.
It is an object of the present invention to provide a novel tapered sectional pole.
It is another object of the present invention to provide a tapered sectional pole which is stronger and easier to manufacture than those proposed heretofore.
It is another object of the present invention to provide a novel tapered sectional pole wherein the various sections are provided with a uniform rate of taper, and with the various gauges for the metal sections decreasing in the direction of the taper.
It is another object of the present invention to provide a tapered sectional pole which can be manufactured with a welded butt-seam in a manner so that the heat effected zone has a range of less than .25 inch.
It is still another object of the present invention to provide a tapered sectional pole wherein the overlap between sections is uniform and extends for a distance approximating one hundred thirty percent of the diameter of the sections in the overlapped area.
Other objects will appear hereinafter.
For the purpose of illustrating the invention there is shown in the drawings a form which is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.
FIGURE 1 is an elevation view of a sectional pole in accordance with the present invention.
FIGURE 2 is a sectional view taken along the lines 22 in FIGURE 1.
FIGURE 3 is a partial perspective view illustrating the manner in which the pole of the present invention will be shipped.
Referring to the drawing in detail, wherein like numerals indicate like elements, there is shown in FIGURE 1 a tapered sectional support pole as 10. a
The pole 10 is illustrated as being assembled in an upright position and supported in a manner so that a substantial portion of the larger diameter end of section 14 is embedded in the ground or other supporting surface 12. The pole 10 includes overlapping tapered sections 14,- 16, 18 and 20. While only four such sections are illustrated in the drawing, it will be appreciated that a greater or lesser number of sections may be utilized. The lowermost section 14 will have an axial length corresponding to approximately fifteen percent of the height of the pole embedded in the ground or other supporting surface 12.
The uppermost end of section 20 is telescoped into a socket 22 having bracket arms 24 and 26 integral with and extending in opposite directions therefrom. The bracket arms 24 and 26 are preferably disposed at an angle of approximately fifteen degrees with the horizontal. Bracket arm 24 terminates in a downwardly directed lamp 28 and bracket arm 26 terminates in a downwardly directed lamp 30. While the bracket arms 24 and 26 are illustrated as supporting lamps, it will be appreciated that other devices may be supported thereby, such as street directional signals, signs, etc. Further, it is to be noted designated generally that other devices may be supported from the pole 10,
such as antennas, telephone, or electrical distribution lines, support platforms, etc.
As shown more clearly in FIGURE 2, the bottom portion of each individual section is telescoped over the top portion of the section therebelow. Hence, the bottom of section 18 telescopes over the top portion of section 16 with the amount of overlap being the linear distance between edges 32 and 34. A mark 38, see FIGURE 1, is applied to the upper portion of each section. The mark 38 is in the shape of an arrowhead and has a length corresponding to the length of the overlap of the various sections. When assembling the sections, pressure will be applied to the uppermost section until the lowermost edge such as edge 34 obscures the point of the arrowhead mark 38.
The amount of the overlap is a uniform percentage of the diameter at the bottom of the overlapping section. Hence, I have found that the strongest joint is obtained when the distance between edges 32 and 34 corresponds to about one hundred thirty percent of the inside diameter of section 18 at edge 34. A strong joint will be obtained if the overlap is as low as one hundred twenty-five percent of the last-mentioned diameter. Increasing the amount of overlap beyond one hundred fifty percent of said diameter does not increase the strength of the joint and results in an inefficient use of the materials.
Each of the tapered sections of the pole are preferably formed from sheet metal which has been folded to a position so that its side edges may be secured together with a butt-joint 36 by a seam weld extending therealong. A successful welding procedure has been developed which results in a balance between high hardness and loss of cold working. I 'have determined that the best results when working with thin gauge material and when desiring to obtain a non-porous weld is to keep the weld as narrow as possible.
I have developed a welding process which utilizes a Welding current at a precise and consistent voltage. A dry carbon dioxide shielding gas is utilized in the welding process. The weld deposit is exceptionally low in hydrogen content resulting in a combination of high tensile strength and low ductility. I prefer to use a filler wire .having the following analysis:
By using a low voltage on the order of twentyone volts and high current densities such as 120 amp, I am able to weld. at a high rate of speed such as 60 to 80 inches per minute. The weld and heat effected zone is extremely narrow, such as .25 inch max- A grooved copper back-up chill bar ona mandrel is utilized. The
chilling effect of the back-up bar is responsible for maintaining the extremely narrow heat-affected zone.
A special welding fixture. in the nature of a ten foot horn jig has been developed to support the various sections during the welding of the butt-joint. The jig is constructed in a manner so that the horn may be removed and others substituted therefor so that it may accommodate the difiereing tapered sections. A seam. alignment device having clamping fingers is provided to hold the preformed sections rigidly against the back-up bar while the sections are being provided with a butt-joint weld by an electric arc process. As a result of the rigid clamping of the sections during Welding, and the extremely small heat zone of the weld, the side walls of the various sections remain straight with no appreciable divergence from a true circular cross section.
The poles of the present invention may be made from various types of material including aluminum. This provides for greater versatility. In order to utilize an aluchanging the nature of the sections above the minum pole, the prior art had to employ a different set of dies having a different set of cutting teeth angles.
The various sections of a pole will be shipped in the manner illustrated in FIGURE 3. Material reductions in shipping charges can be attained by shipping the sections one inside the' other as illustrated. When assembling a pole, the sections may be assembled without regard to the location of the butt-weld on each section. The sections are driven together so as to obtain the desired amount of overlap by use of a hammer or hand operated pump which cannot apply a pressure greater than 3,000 pounds per square inch. Since the sections have been designed in accordance with a true right cone having a uniform taper of .0239 inch per inch, the sections can only overlap each other for a distance corresponding to one hundred thirty percent of the inside diameter of the lowermost end of the top section being applied. Hence, the amount of overlap between sections cannot be greater than the last mentioned figure. If pressure sufiicient to cause a greater overlap is applied, the sections will deform. It is to be noted that the various tapered sections could be made from two halves thereby resulting in two welded butt-joints.
The advantages of the pole 10 of the present invention include forty-five percent more compression strength, even strength over the entire length of the pole, reduction in production time and costs, elimination of bottlenecks in production as associated with the tongue and recess type of joint on the tapered sections, increased field of application and greater safety due to the increased and stabilized compression loads, ease in assembly due to the elimination of the necessity of particularly orientating the seam joints of the various sections, etc.
To increase the working load of a pole, it is not necessary to change the gauge of every section. Instead, only the top section or sections at and above the point where buckling will occur, due to a specified lateral load applied to a pole having a chosen taper, need be removed. Additional sections may then be added to the bottom of the pole so that the desired height of thepole may be maintained. A pole with a large lateral load at the top might require, with the chosen taper, a series of sections of uniform wall thickness. By imposing a second lateral load at a lower level, the thickness of the lower sections could be increased to accommodate this load without point of application of the second load.
In lieu of sheet metal having a seam weld, the sections could be made from Fiberglas with only sufiicient adhesive or resin as is needed to bind the fibers together. The fibers may be spirally Wound and designed to have the characteristics of the sections described above except for the seam weld. The sections may be round, square, elliptical, octagonal, etc., in cross section. It will be appreciated that the sectional modulus of a beam is ascertained by dividing its moment of inertia by the distance to the fiber carrying the greatest stress.
The present invention may be embodied in other specific .forms'without departing-from the spirit or'essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than'to the foregoing specification as indicating the scope of the invention.
1. In a pole structure comprising a plurality of hollow overlapping tapered sections, each section overlapping the section therebelow by a distance between one hundred twenty percent and one hundred fifty percent of the greatest inside diameter on the overlapping section, each section being a tapered metal member having a butt-joint weld extending in a longitudinal direction thereof, said tapered sections having a thinner wall thickness than sections therebelow, and eachsection having a uniform taper so that a pole constructed thereof will havea taper corresponding to a true linear cone.
2. In a pole structure in accordance with claim 1 wherein the amount of overlap is one hundred thirty percent of the greatest diameter in the area of overlap.
3. In a pole structure in accordance with claim 1 wherein said taper is .0239 inch per inch.
4. A pole structure comprising a plurality of hollow overlapping tapered sections, means for increasing the sectional moduli throughout the length of the pole formed by the overlapping sections in the same proportions as the bending moment, said means including a uniform taper on each section so that the pole will have a taper corresponding to a true linear cone, the wall thickness of each of said sections being uniform with the thickness of the sections increasing in a direction from the smaller diameter end of the pole toward the other end of the pole, each section being a tapered sheet metal member having a seam weld extending in a longitudinal direction, and each section overlapping the next adjacent section by a distance corresponding to between 120% and 150% of the greatest inside diameter on the overlapping section.
5. A pole structure comprising a plurality of hollow overlapping tapered sections, means for increasing the sectional moduli throughout the length of the pole formed by the overlapping sections in the same proportion as the bending moment, said means including a uniform taper on each section so that the pole will have a taper corresponding t-o a true linear cone, each section having a thinner wall thickness than the section therebelow while having a uniform wall thickness throughout its length, and each section overlapping the next adjacent section by a distance corresponding to approximately 130% of the largest inside diameter on the overlapping section.
References Cited by the Examiner UNITED STATES PATENTS 183,921 10/1876 Haas 52-726 1,179,853 4/1916 McCulloch 29-155 X 1,891,620 12/1932 Crawford 52-726 2,066,419 1/1937 Pfistershammer 52-721 3,034,209 5/1962 Bianca et al 52-726 X FRANK L. ABBOTT, Primary Examiner.
R. S. VERMUT, Assistant Examiner.