Method and apparatus for extruding a honeycomb structure

Apparatus for extruding a honeycomb structure including a plurality of thin-walled cells from an extrudable Bingham plastic material comprising:

• first means for creating shearing flow in said material while reducing the cross-sectional area of said material from an initial cross-sectional area to a lesser cross-sectional area;
• second means for receiving said material from said first means for establishing substantial plug flow in said material while the lesser cross-sectional area of the material is substantially maintained;
• and
• extrusion die means including a plurality of passageways for forming said structure, said passageways including a plurality of feed holes communicating with interconnected discharge slots sequentially in the direction of extrusion, said die means being located adjacent said second means for receiving said material from said second means while in the state of substantial plug flow, said die means having an exposed flow-through cross-sectional area substantially corresponding to said lesser cross-sectional area.

A method of extruding a honeycomb structure having a plurality of thin-walled cells from an extrudable Bingham plastic material using an extrusion die having passageways including a plurality of feed holes communicating with interconnected discharge slots sequentially in the direction of extrusion, said method comprising:

• advancing the material toward said die;
• reducing the cross-sectional area of the material transverse to the direction of advancement;
• creating shearing flow in the material as the material is advanced toward the die and the cross-sectional area is reduced;
• maintaining constant the reduced cross-sectional area of the material;
• establishing plug flow in the material and substantially terminating shearing flow in the material while maintaining constant the reduced cross-sectional area prior to reaching the die;
• and
• extruding the material through the die so as to form the structure with a cross-sectional area substantially conforming to the reduced cross-sectional area of the material prior to reaching the die.