Patent ID: 8617330

Claim:
A process for the continuous production of a stiff polymeric foamed sheet, comprising the following steps: a) contacting a polymeric mass and other components of a mixture in an extruder of a first assembly line; b) producing a foamed sheet ( 5 ) by extrusion, such that foaming begins at an outlet of an extrusion head, wherein the extrusion head is a multi-channel head and includes a T-shaped material distributing channel, a plurality of distributing channels downstream from the T-shaped material distributing channel, the plurality of distributing channels having a smaller cross section than the T-shaped material distributing channel, and wherein the plurality of distributing channels are connected to additional multiple channels having cross-sections that are smaller than cross-sections of the plurality of distributing channels, and wherein the outlet includes a restricting bar and flexible opening lips, so as to gradually increase pressure on the mixture until the mixture reaches the lips of the outlet; c) calibrating the foamed sheet; d) cooling and drawing the foamed sheet so as to form a foamed core; e) producing structural skins in a second assembly line separate from the first assembly line; f) feeding the foamed core ( 5 ) and the structural skins ( 55 ) into a third assembly line; g) attaching the structural skins ( 55 ) to the foamed core ( 5 ) by heat and pressure to form sandwich panels in the third assembly line; and h) longitudinally and transversely cutting the sandwich panels to predetermined dimensions.