US 5,037,592 AGranted

Process and apparatus for making a molded article from expandable synthetic resin particles

AssigneeErlenbach GmbH & Co. KG

InventorHans Erlenbach

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Abstract

To make a molded article from expandable synthetic resin particles, especially polystyrene particles, the cooling of the individual mold wall portions is effected exclusively by evaporating condensate obtained from stream, advantageously condensate which accumulates in stream compartments on the exterior or back sides of the mold walls which was fed in for heating of the mold wall portions and fusing the synthetic resin particles. This evaporation of condensate is effected on the back surfaces of the mold wall portions facing the steam compartments because of a low pressure or suction produced in the steam compartments. The condensate is fed in hot at or just below the boiling temperature of the condensate. Surfaces of the mold wall portions facing the steam compartment have increased surface area by reason of spherical surface-area increasing elements which form constricted passages between a plurality of interior reservoir cavities and the outside steam compartment.

Claims15

Dependent claims

A method of making a molded article from a mass of polystyrene particles, comprising the steps of:

(a) introducing said mass of polystyrene particles into a two-part mold enclosing said particles in a mold cavity defined by wall portions forming steam compartments externally of said cavity;
(b) hearing said particles through said wall portions by feeding steam into said steam compartments thereby expanding said particles and forming condensate in said steam compartments;
(c) fusing particles of said mass expanded in step (b) with each other by introducing steam into said cavity;
and
(d) stabilizing an article formed by fusion of the expanded particles with each other by:
(d.sub.1) excavating steam from said steam compartments and from said cavity,
(d.sub.2) collecting condensate from said steam compartments,
(d.sub.3) venting said steam compartments,
(d.sub.3') heating said condensate to a temperature at most equal to a boiling temperature of said condensate but at least 10.degree. K. less than said boiling temperature while venting said steam compartments in step (d.sub.3), and
(d.sub.4) spraying condensate collecting in step (d.sub.2) and heated in step (d.sup.3') against surfaces of said wall portions defining said compartments and opposite surfaces thereof facing said cavity at an ambient pressure of said steam compartments and at said temperature.

7 more elements

Dependencies are inferred from the claim text.