Extrusion die and method for producing extrusion die for forming a honeycomb structure

A method for producing an extrusion die useful in making a honeycomb structure having numerous discrete through-holes separated by walls, comprising the steps of:

• forming in one surface of a metallic die body a network of pooling slots interconnected throughout said network and having a depth extending from said one surface inwardly toward an opposed surface to a certain level,
• securing by bonding a metallic plate directly to said one surface to cover all of said slots,
• before said bonding of said plate to said one surface, forming recesses in at least one of the said plate and said one surface to increase the bonding area therebetween,
• forming through said plate a network of interconnected extrusion slots in communication with said pooling slots for extruding said walls, and
• forming numerous discrete feed passageways for initially receiving extrudable material and feeding same to said pooling slot network, said passageways extending from said opposed surface inwardly toward said one surface to the said level of said pooling slots for direct communication therewith inside said body,
• said pooling and extrusion slots being formed to cause extrudable material received by the pooling slots from said feed passageways to be spread throughout said pooling slot network so that said material can be extruded continuously through the whole of said extrusion slot network to make said walls solid.

A method for producing an extrusion die useful to make a honeycomb structure, comprising the steps of:

• forming on one surface of a metallic die body multiplicity of discrete columns having outer ends of given size and extending perpendicular from said surface so as to form between said columns a network of pooling slots interconnected throughout said network,
• forming on said outer column ends respective discrete metallic platelets each having an area larger than the respective outer column end and together forming between themselves a network of interconnected criss-crossing extrusion slots forming a multiplicity of intersections and being coextensive with said pooling slot network with the extrusion slots being substantially narrower than their respective pooling slots with which they communicate,
• said forming of a respective platelet on column ends resulting in platelet-column sets and including the forming in each set of at least one recess for increasing the effective contact area therebetween, and
• forming in said die body to a depth of about 13 mm. to about 16 mm. a multiplicity of discrete feed passageways which are substantially less in number than the number of extrusion slot intersections but substantially wider than said pooling slots and which communicate directly with said pooling slots.

An extrusion die for making a honeycomb structure, comprising:

• an integral metallic die body having two opposed surfaces from one of which a multiplicity of discrete feed passageways extend inwardly to a level of about 13 mm. to about 16 mm. toward the other of said surfaces and having in said other surface a grid network of criss-crossing pooling slots running transverse to said passageways and forming a multiplicity of intersections and being interconnected throughout said network and extending from said other surface toward said one surface to said level at which said passageways meet said slots for direct communication, said pooling slots being formed by individual columns integral with said die body,
• the number of said feed passageways being substantially less than said pooling slot intersections, and
• a multiplicity of discrete metallic platelets each larger than said columns in transverse dimensions and nonintegral with said die body but respectively bonded permanently to said columns and together forming a grid network of interconnected extrusion slots respectively registering on said pooling slots but having a width substantially narrower than said pooling slots,
• there being a recess in each set of platelet and column for increasing the effective bonding contact area therebetween.