Method for manufacturing integral elastic supports using an expandable resin

A method for manufacturing an integral elastic support formed by an upper covering, by an intermediate filler and by a lower semirigid shell, employing a mold formed of a lower part having an upwardly open cavity and reproducing the resting surface of the support, a substantially flat upper part reproducing the bottom of the support, and a first locking plate intermediate the upper part and the lower part for engaging and retaining the covering, said method comprising the steps of:

• a) opening the mold so as to expose the cavity of the lower part of the mold;
• b) depositing on said lower part a substantially airtight covering sheet having an excess border which exceeds the contour of said cavity;
• c) securing said excess border against said lower part by superimposing said first locking plate thereon with the excess border located therebetween;
• d) vacuum forming the covering sheet to produce a deformed sheet by producing a vacuum on an internal wall of said cavity;
• e) pouring a first layer of a gel compound in a fluid state onto the bottom of the deformed sheet;
• f) detachably coupling a shell made of semirigid plastic to the upper part of the mold;
• g) pouring a second layer of an expandable resin in the fluid state onto said first gel layer;
• h) closing the mold by superimposing and locking the upper part of the mold on said first locking plate and on said lower part of the mold;
• i) maintaining the mold in such closed condition to allow the foaming and complete polymerization of the resin and of the gel compound;
• and
• k) opening the mold and removing the finished support;
• wherein the expandable resin is poured onto the gel compound after a period of time that is sufficient to allow the gel compound to assume a certain consistency and shape of its own but which is shorter than the full polymerization time of the compound, so as to allow the gel compound to react at least partially with said expandable resin.