Vertically flaring concrete form

Claim 1

A concrete form having an axis and a conical, convex surface about said axis, said form comprising: (a) a plurality of axially consecutive, annular form elements, (1) each form element including a plurality of plate members and fastening means fastening said plate members to each other in a closed loop in circumferentially juxtaposed relationship, (2) each plate member having an outer face constituting a portion of said surface, an inner face parallel to said outer face and obliquely inclined relative to said axis, and first and second, axially spaced, circumferentially elongated edge portions of different length connecting said faces; and (b) first and second coupling members fixedly secured to the inner face of each plate member and projecting from the associated inner face in a radially inward direction axially adjacent said first and second edge portions respectively, (1) said first coupling member projecting axially beyond the adjacent first edge portion, (2) each coupling member having a face cylindrically arcuate about and parallel to said axis of said conical form and conformingly engaging a corresponding face of a coupling member on a plate member of an axially consecutive form element in radially abutting engagement, thereby coupling two form elements to each other.