Apparatus and method for the production of foamed polymeric material

An apparatus for the production of foamed polymeric material, in particular polyethylene and polypropylene, by means of a physical foaming process, the apparatus comprising an extrusion machine and a feeding unit for feeding the extrusion machine with a blend of plastic material,

• wherein the extrusion machine comprises
• a machine body,
• a cylindrical barrel accommodated in the machine body and connected with a first end thereof to the feeding unit to receive from the feeding unit said blend of plastic material,
• a pair of screws received in the cylindrical barrel and having axes of rotation arranged of parallel to each other,
• a driving unit for driving the screws into rotation at a same speed, but in opposite directions, around their respective axes of rotation,
• a gas tank for containing a foaming gas,
• injection means for injecting the foaming gas coming from the gas tank into the cylindrical barrel,
• a head mounted at a second end of the cylindrical barrel opposite to said first end, and
• heating means arranged around the cylindrical barrel to transfer heat thereto,
• wherein said gas tank contains carbon dioxide as a foaming gas.