Patent ID: 6467749
Filing Date: 2002-10-22
Classification: B28B,E04G

Abstract:
In a concrete column forming tube for receiving poured concrete therein to produce a concrete column and in which said forming tube comprises an elongate rigid cylindrical paper tube capable of receiving concrete therein to form a column and including spirally-wound plies of paper adhered together and defining an inside wall surface having spiral seam lines thereon, and a centrifugally-cast plastic coating sprayed onto said inside wall surface of said spirally-wound paper tube while said tube is rotating for producing a smooth inside coated surface on said forming tube having a thickness and smoothness sufficient to eliminate spiral seam lines and other undesirable line characteristics on an outside surface of the formed concrete column; the combination therewith of:a generally flat tear strip positioned between said inside surface of said cylindrical paper tube and said plastic coating prior to centrifugal-casting thereof so as not to interfere with said smooth inside coated surface of said forming tube, said tear strip extending longitudinally of said column forming tube over the entire length of said column forming tube, said tear strip having a predetermined width and being readily detachable from said plastic coating, so that, when it is desired to remove said forming tube from the concrete column produced, said tear strip is pulled from one end of said forming tube to the other end to tear open and remove a section of said cylindrical paper tube having a width generally equal to the predetermined width of said tear strip for producing a longitudinally-extending gap therein of a width generally equal to the predetermined width of said tear strip to receive therein a device for cutting through said plastic coating, and wherein said tear strip further includes a continuous wire in longitudinal edges thereof.