Method of making extrusion dies from powders
AssigneeCorning Incorporated
InventorRodney D. Bagley
Life of this patent
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Abstract
A method of forming an extrusion die fabricated from sinterable ceramic or metal powders, for use in forming honeycomb monolith structures including machining of the die in the green state or after partial densification. Alternatively, all or part of the machining can be performed after full densification or sintering.
Claims29
A method of forming an extrusion die from powders, the method comprising:
- compounding solid state sinterable powders by pre-milling the powders with a dispersant and a solvent to form a mixture;
- dissolving or dispersing a high molecular weight thermoplastic polymer in a wax component at a temperature above the melting temperature of the wax to form a molten wax/polymer binder;
- adding the pre-milled powder mixture to the molten wax/polymer binder at a temperature sufficient to blend the powder and molten binder;
- volatilizing the solvent to produce a thermoplastic paste;
- shaping the paste to form a green sinterable preform;
- machining the green preform into the shape of an extrusion die;
- and
- sintering the machined preform to form the die.
A method of forming an extrusion die from powders, comprising the steps of:
- forming a first slurry comprising low shrinkage sinterable powders;
- forming a second slurry comprising high shrinkage sinterable powders;
- shaping the first and second slurries to form a green laminated preform consisting of a first layer of the first slurry formed on a second layer of the second slurry, and a junction between said first and second layer;
- machining the green preform to form to form a plurality of longitudinally spaced feed holes in the second layer, and a plurality of intersecting and laterally criss-crossing discharge slots in the first layer, such that the slots are in communication with the feed holes;
- and
- sintering the machined preform to form the die.
A method of forming an extrusion die comprising a plurality of longitudinally spaced feed holes and laterally criss-crossing discharge slots, the method comprising the steps of:
- providing a mold having a series of core pins defining a reverse or negative pattern of said feed holes;
- shaping sinterable powders in said mold to form a preform such that the length of the core pins is less than the thickness of the preform;
- removing the core pins to reveal feed holes on one portion of the preform;
- machining the opposite portion of the preform to form intersecting and laterally criss-crossing discharge slots such that the slots communicate with said feed holes;
- and
- sintering the preform to form the extrusion die.
A method of forming an extrusion die from powders comprising:
- doping solid state sinterable powders with MgO;
- compounding the doped powders with a binder to form a mixture;
- spray drying the mixture;
- isostatically pressing and shaping the mixture to form a green sinterable preform having an inlet and an outlet portion;
- drying the preform into a chalk-hard or soft-fired state;
- forming a plurality of longitudinally spaced feed holes in the inlet portion of the preform;
- forming a plurality of intersecting and laterally criss-crossing discharge slots in the outlet portion of the preform;
- such that the discharge slots are in communication with the feed holes;
- and
- sintering the preform to form the die.
Dependencies are inferred from the claim text.