Cylinder for helical screw extrusion press - with shrink-fitted internal cover

摘要

Cylinder of a helical screw plastic extruder is provided with a composite internal cover made of steel support layer (4) and a hot isostatically pressed corrosion and wear resistant outer layer (5). This outer layer is shrink-fitted onto the support layer (4) so that it remains at least at working temperature in a pre-stressed condition. Pref., typically the cylinder is made of a cover part and a coolant channel part which are welded together. The thickness of the wear resistant layer is 1/4-1/3 that of the support layer. Both the cylinder and the support layer are made of construction steel with the wear resistant layer made of an alloy with a high vanadium carbide content. ADVANTAGE - Prevents the resistant outer layer from tearing free from the support layer.