Patent ID: 6725539
Filing Date: 2004-04-27
Classification: E01F,H02G,Y10T

Abstract:
A method of making marking posts comprising tubular thermoplastic barrels with upper ends and flanged lower ends, which method comprises the steps of:providing a barrel with first and second ends and a bore extending between and open at said ends; applying heat to said barrel lower end and thereby presoftening same; restraining said barrel along the length thereof against axial movement; providing a mandrel with a base, a mandrel plug mounted on and projecting generally perpendicularly from said base and an annular transition between said base and said plug; providing said transition with a concave, curved configuration; providing a linear actuator with extended and retracted positions; mounting said mandrel on said linear actuator in alignment with said barrel bore; placing said linear actuator in said retracted position; advancing said linear actuator axially to its extended position; telescopically advancing said mandrel plug into said barrel bore; engaging said barrel first end with said mandrel transition; deforming said barrel first end in a first, radial outward direction by advancing said mandrel into said barrel bore and thereby forming a barrel end extension portion; further deforming sand barrel first end in a direction generally axial with respect to said barrel and radially towards same; and maintaining an upwardly-open channel formed by a spacing between said flange rim and said barrel.