Die Assembly And Method Of Extruding Cellular Ceramic Substrates With A Skin
AssigneeCorning Incorporated
InventorMichael James Lehman
Life of this patent
Estimating the term…
Abstract
An extrusion apparatus including a die and a mask are provided such that no slots feed directly into the longitudinal skin forming gap between the mask and the die. In a method of forming a die adapted to improve skin uniformity of extruded cellular ceramic substrates a slotted block of die material is provided including central slots adapted to form a cellular matrix of the substrate and peripheral slots located outwardly of the central slots designed to be covered by a skin former mask and adapted to extrude peripheral batch material. An arcuate skin former is cut corresponding to a target shrinkage so as to intersect the slotted block such that skin flow from tangent slots at 90 degree positions of the die is limited to the peripheral batch material.
Claims15
A porous ceramic honeycomb body, comprising:
- a honeycomb structure comprising perpendicularly intersecting porous ceramic walls;
- and
- a coextruded skin surrounding and directly adjacent to the honeycomb structure, the skin comprising first portions of uniform thickness t with each other at the 90 degree positions of the honeycomb structure and second positions of a thickness greater than the uniform thickness t off the 90 degree positions of the honeycomb structure.
A method of making a porous ceramic honeycomb body comprising a coextruded skin, the method comprising:
- extruding ceramic precursor batch through an extrusion die to form a green substrate, wherein the die comprises:
- a slotted block of die material including central slots adapted to form a cellular matrix of the substrate and peripheral slots located outwardly of the central slots designed to be covered by a skin former mask and adapted to extrude peripheral batch material;
- an arcuate skin former corresponding to a target shrinkage so as to intersect said slotted block such that skin flow from tangent slots at 90 degree positions of the die is limited to said peripheral batch material;
- and wherein
- values for a slot width (W), a slot spacing (S) and a face gap (F), and ranges of O and I as follows:
- Omin=a minimum outer slot to mask distance=½W;
- Imax=a maximum inner slot to pin face distance=S−F−Omin;
- Imin=a minimum inner slot to pin face distance=½W;
- and
- Omax=a maximum outer slot to mask distance=S−F−Imin,
- wherein said skin former is disposed at values of O and I in said ranges.
A method of making a porous ceramic honeycomb body comprising a coextruded skin, the method comprising:
- extruding ceramic precursor batch through an extrusion die to form a green substrate, and
- firing the green substrate to produce a porous ceramic honeycomb body, wherein the porous ceramic honeycomb body comprises:
- a honeycomb structure comprising perpendicularly intersecting porous ceramic walls;
- and
- a coextruded skin surrounding and directly adjacent to the honeycomb structure, the skin comprising first portions of uniform1 thickness t with each other at the 90 degree positions of the honeycomb structure and second positions of a thickness greater than the uniform thickness t off the 90 degree positions of the honeycomb structure.
Dependencies are inferred from the claim text.