US 4,600,548 AGranted

Method of forming the primary core of a prestressed concrete pipe

AssigneeVinen Corp.

InventorVito Nenna

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Abstract

The present invention relates to a method of forming the primary core of a concrete pipe. A steel cylinder is disposed vertically on the base of the pipe forming machine. A conventional rotary packerhead having a diameter less than the inner diameter of the steel cylinder is lowered concentrically to the bottom thereof. Concrete is then introduced within the steel cylinder through the upper end thereof. The packerhead is rotated to force the concrete into the annular gap between the packerhead and the steel cylinder. As the primary core is formed, the packerhead is raised and rotated while concrete is introduced within the steel cylinder, thereby forming a primary core consisting of a steel cylinder having an inner lining of concrete. In an alternative embodiment, the steel cylinder is completely embedded within the concrete.

Claims1

Dependent claims

A method of forming an adherent concrete lining on the inside surface of a cylindrical metal pipe and an adherent concrete casing about the outside surface of the metal sleeve comprising the steps of:

(a) positioning a cylindrical metal sleeve having a predetermined height in substantially vertical and coaxial relationship within a cylindrical mold having substantially the same height as the metal sleeve such that the outer surface of the metal sleeve is spaced from the inner surface of the mold;
(b) supplying concrete to the space between the outer surface of the metal sleeve and the inner surface of the mold while vibrating the mold to compress the concrete therebetween to form an adherent concrete casing about the outer surface of the metal sleeve;
(c) simultaneously with step (b), supplying concrete to the interior of the metal sleeve;
(d) simultaneously with step (b), radially compressing the concrete in the metal sleeve against the inner surface thereof to form a concrete lining along the length of the inner surface of the metal sleeve;
and
(e) removing the metal sleeve having the inner concrete lining and the outer concrete casing from the mold.

3 more elements

Dependencies are inferred from the claim text.