Molding system with retracting mold

Abstract

A molding system for molding large diameter chimney liners of fibreglass reinforced plastic (FRP) utilizes a vertically oriented cylindrical mold for use in combination with a working platform mounted on a vertical ram. The mold is of modular construction, having a plurality of axially spaced-apart spiders, each spider being segmented into a plurality of adjoining tri-angulated segments to form a polygon, to the outer sides of which are attached chordal segments to complete the circular form of the spider. Vertically axially extending ribs interconnect the spiders, with a flexible skin being applied thereabout. The provision of expansion means on the spiders increases the diameter of the mold to its working diameter, so that, upon completion of molding a liner, the action of the spider expansion means is reversed, causing contraction of the mold sufficient to facilitate ready axial separation of the mold and liner. The modular construction of the mold, including radial adjustability of the spider segments permits the mold to be built up to different selected diameters so that liners having a size range between 20 feet and 30 feet diameter may be readily fabricated using one basic mold.

Dependencies are inferred from the claim text.