Patent ID: 7101166

Claim:
An apparatus for extruding a ceramic molding, comprising: a molding die, to form a ceramic molding, and a screw extruder containing an extrusion screw to knead and guide a ceramic material toward the molding die, wherein said extrusion screw has a pressure screw part provided with a first lead of at least one thread in the form of a spiral ridge, on an outer peripheral surface of a first shaft body and, on a downstream end, a diffusion screw part coaxial to the first shaft body and provided with a second lead of at least one thread in the form of a spiral ridge on an outer peripheral surface of a second shaft body which rotates integrally with the first shaft body, wherein said diffusion screw part has a diameter larger than that of the pressure screw part, and wherein said second shaft body of the diffusion screw part has, at least at its downstream end in the axial direction, a diameter reducing part that is tapered so that its diameter reduces to its downstream end, said second lead extending along said diameter reducing part.