Die for extruding and wash coating

Abstract

A honeycombed structure is extruded and wash coat applied to the interior channels of the structure before the honeycomb structure is separated from the die in which it is formed. This method produces the honeycombed structure using a die that includes a die body having an inlet and an outlet side, a plurality of parallel pins defined by the body that correspond to the shape of the channels in the honeycombed structure, and a discharge zone that communicates directly with the outlet side of the die and is defined by the open area between the pins. The extrudable material enters the discharge zone from a series of feed passages defined by the pins and a plurality of webs that interconnect the pins. Each pin has an interior duct with an opening at the end of each pin. A series of internal passages in the die body receive fluid from one or more ports on the periphery of the die and distribute the fluid to the ducts. Spraying the wash coat from the ends of the pins eliminates the need for a separate wash coat step after the honeycombed structure has been formed. In addition, wash coat is continually applied to the interior walls of the channel by the duct as the channel passes the end of the pin so that the entire length of the channel is covered with wash coat. This invention can be used in a wide variety of die configurations, but is especially suited for a die having segmented slots for feed passages and square channel forming pins defined in part by the segmented slots.