Producing reinforced plastic pipe with a multi-mandrel machine

Abstract

Plastic pipe is continually produced from a curable resin on a plurality of horizontal mandrels which are repeatedly simultaneously moved between plastic pipe production stations. There is at least one station for applying resin to a mandrel, at least one station for curing resin on the surface of a mandrel, and at least one pipe removal station for removing pipe from a mandrel. The pipe stations are substantially radially equidistant from a central horizontal axis and are circumferentially spaced apart by substantially equal increments around the horizontal axis. Each mandrel is progressively rotated between the stations. The temperature of each mandrel is controlled by passing a fluid through the mandrel. Heating fluid passes through mandrels in resin cure stations and cooling fluid passes through mandrels in resin application and pipe removal stations. A control system minimizes mixing of the cooling and heating temperature control fluids when the mandrel is rotated between stations. A distributor system distributes temperature control fluids from fluid reservoirs to the mandrels. Mandrels having a flow path for the temperature control fluid include a cylindrical shell closed at one end and open at the opposed end with a fluid inlet and outlet at the open end. The flow path through the mandrel comprises an open outlet duct within the shell for transferring fluid out of the mandrel through the fluid outlet and an inlet passage between the duct and the inner surface of the shell for transferring fluid into the mandrel from the fluid inlet.