Preparation of a plastic for its extrusion particularly in the form of a gaged bead intended to be used as a seal and interlayer in multiple glazings

An installation for preparing a plastic material of the type having a butyl rubber base from a mass of said material in the raw state having a high viscosity and a high hardness, and for extruding said plastic in the form of a gaged bead having a viscosity and a hardness lower than those of said material in the raw state, comprising:

• a tank containing raw plastic material and having a cover applied with pressure against said material, said cover having an outlet orifice and a shape such that the section of the volume of material enclosed by said cover is smaller the closer said material is to said outlet orifice, said cover also being equipped on a face thereof oriented toward the material with heating appendages that can plunge into said material,
• a first pump in fluid communication with said outlet orifice for providing a continuous delivery of said material under a high pressure,
• variable volume magazine means located downstream from said pump in a direction of material flow, for providing continuous delivery of said material under pressure, said magazine means consisting of a cylinder and a piston returned to the inside of the cylinder with a constant force less than the force exerted by the material feeding said magazine, and
• an output nozzle downstream from said magazine.