Extrusion die assembly for forming honeycomb structures having thickened outer skin

Claim 2

An extrusion die assembly for extruding a structure having a thickened outer skin, the assembly including an extrusion die having a plurality of axially extending and generally parallel feedholes, the die having an inlet face and an outlet face, the outlet face having a plurality of discharge slots, the latter being associated with rows and columns of axially extending pins integral with the die, characterized by, a die mask at the periphery of the discharge end of the die, the mask having a radially inwardly extending lip axially spaced downstream from the ends of said pins and overlying a peripheral region of the die outlet face, said mask lip having an edge, said mask lip exerting a radially inwardly directed force on the extruded material passing through the central portion of the die to thereby form a thickened skin on the material being extruded, and means for independently controlling the volume and rate of flow of material which flows in a downstream direction towards and beneath said mask lip and which forms a thickened skin, whereby the volume of skin forming batch material can be varied substantially independently of the volume of batch material fed to the central portion of the die.

Claim 3

The die assembly of claim 1, wherein said peripheral region of said die outlet face is annularly continuous.

Claim 4

An extrusion die assembly for extruding a structure having a thickened outer skin, the assembly including an extrusion die having a plurality of axially extending and generally parallel feedholes, the die having an inlet face and an outlet face, the outlet face having a plurality of discharge slots, the latter being associated with rows and columns of axially extending pins integral with the die, characterized by, a die mask at the periphery of the discharge end of the die, the mask having a radially inwardly extending lip axially spaced downstream from the ends of said pins and overlying a peripheral region of the die outlet face, said mask lip projection having an edge, said mask lip exerting a radially inwardly directed force on the extruded material passing through the central portion of the die to thereby form a thickened skin on the batch material being extruded, said means for controlling comprising a forming plate positioned over the die inlet face and in surface contact therewith, said forming plate having a central opening congruent with the cross sectional shape of the structure being extruded, the forming plate having a plurality of axially extending, flow controlling openings spaced radially inwardly from the edge of said forming plate central opening, each of said flow controlling openings being aligned with and adapted to feed the input end of at least one die feedhole.

Claim 5

An extrusion die assembly for extruding a structure having a thickened outer skin, the assembly including an extrusion die having a plurality of axially extending and generally parallel feedholes, the die having an inlet face and an outlet face, the outlet face having a plurality of discharge slots, the latter being associated with rows and columns of axially extending pins integral with the die, characterized by, a die mask at the periphery of the discharge end of the die, the mask having a radially inwardly extending lip axially spaced downstream from the ends of said pins and overlying a peripheral region of the die outlet face, said mask lip projection having an edge, said mask lip exerting a radially inwardly directed force on the extruded material passing through the central portion of the die to thereby form a thickened skin on the batch material being extruded, said means for controlling comprising a forming plate positioned over the die inlet face and in surface contact therewith, said forming plate having a central opening congruent with the cross sectional shape of the structure being extruded, the forming plate having a plurality of axially extending, flow controlling openings spaced radially inwardly from the edge of said forming plate central opening, each of said flow controlling openings being aligned with and adapted to feed the input end of at least one die feedhole.

Claim 6

The die assembly of claim 1, 2 or 3 wherein said die mask and said forming plate are annular.

Claim 7

The die assembly of claim 1, 2 or 3 wherein the die assembly extrudes a honeycomb structure.

Claim 8

The die assembly of claim 1, 2 or 3 wherein said flow controlling openings are the same, smaller, larger and/or a combination of sizes in relation to said feedhole.

Claim 9

The die assembly of claim 1, 2 or 3 wherein the discharge slots criss cross one another.

Claim 10

The die assembly of claim 1, 2 or 3 wherein the die mask is spaced from the discharge surface of the die by a shim.

Claim 11

The die assembly of claim 1, 2 or 3 wherein a portion of the die outlet face which is overlied by said lip has an annular groove extending inwardly of the die from said outlet face.

Claim 12

The die assembly of claim 1, 2 or 3 wherein the die mask is in contact with the discharge face of the die.

Claim 13

The die assembly of claim 1, 2 or 3 wherein the edge of the mask lip is axially aligned with the edge of the forming plate central opening.

Claim 14

The die assembly of claim 1, 2 or 3 wherein that annular region of the discharge slots of the die which is axially aligned with an annular zone defined by said flow controlling openings in said forming plate contains discharge slots which are wider than the remaining discharge slots.