US 11,834,856 B2
Tapered spiral welded structure
Eric D. Smith, Boulder, CO (US); and Alexander H. Slocum, Bow, NH (US)
Assigned to KEYSTONE TOWER SYSTEMS, INC., Denver, CO (US)
Filed by Keystone Tower Systems, Inc., Denver, CO (US)
Filed on Dec. 30, 2020, as Appl. No. 17/137,885.
Application 15/276,042 is a division of application No. 14/247,856, filed on Apr. 8, 2014, granted, now 9,475,153, issued on Oct. 25, 2016.
Application 17/137,885 is a continuation of application No. 16/109,072, filed on Aug. 22, 2018, granted, now 10,895,088.
Application 16/109,072 is a continuation of application No. 15/276,042, filed on Sep. 26, 2016, granted, now 10,060,149, issued on Aug. 28, 2018.
Application 14/247,856 is a continuation of application No. 12/693,369, filed on Jan. 25, 2010, granted, now 8,720,153, issued on May 13, 2014.
Prior Publication US 2021/0115690 A1, Apr. 22, 2021
Int. Cl. E04H 12/08 (2006.01); B21C 37/12 (2006.01); B21C 37/18 (2006.01); E04H 12/34 (2006.01); B23K 31/02 (2006.01)
CPC E04H 12/08 (2013.01) [B21C 37/124 (2013.01); B21C 37/185 (2013.01); B23K 31/02 (2013.01); E04H 12/342 (2013.01); Y02E 10/728 (2013.01); Y10T 29/49318 (2015.01); Y10T 29/49826 (2015.01); Y10T 428/12 (2015.01)] 9 Claims
OG exemplary drawing
 
1. A tower comprising:
a sheet formed as a frusto-cone having a base and a top, wherein the base has a first diameter,
the top has a second diameter less than the first diameter of the base,
the sheet has a first edge and a second edge coupled to one another along a spiral seam extending from the base to the top and centered about a center axis defined by the frusto-cone,
the sheet has a plurality of cross-seams intersecting the spiral seam,
consecutive cross-seams of the plurality of cross-seams are spaced apart from one another by progressively decreasing distances along the spiral seam in a direction from the base to the top of the frusto-cone, and
each cross-seam of the plurality of cross-seams has the same length.