PROCESSES AND APPARATUSES FOR PERFORATING SMOOTH, CLOSED-CELL SURFACES OF OPEN-CELL PLASTIC FOAM SHEETS

摘要

Open-cell plastic foam sheets with smooth, closed surfaces are heated up to a predetermined temperature after extrusion, are thermoformed in a thermoforming unit with the aid of a vacuum on both sides and are thermoset. One of the two closed surface skins of the plastic foam sheet is perforated with the aid of needles 4 arranged movably in a mold block 11. The mold block 11 is a component part of a thermoforming unit 10 and, together with a further mold block 9, forms the mold of this thermoforming unit. The mold block 11 for the inner side 13 of a plastic foam sheet 16 comprises a male mold 1, a cooling plate 2, a vacuum plate 3, the movable needles 4, a needle plate 5, springs 6 for the return of the needle plate and also diaphragms 7 and a mounting plate 8, which are held together by screws 30.