Extrusion die for biodegradable material with die orifice modifying device and flow control device

An extrusion die for extruding biodegradable material, said extrusion die comprising:

• a cylindrical mandrel;
• a cylindrical outer ring positioned around said mandrel;
• an annular extrusion orifice between said mandrel and said outer ring;
• a member in communication with at least one defining member of said annular extrusion orifice which produces angular relative movement between said outer ring and said mandrel;
• a flow control device which controls flow of biodegradable material through the extrusion die, wherein the flow control device comprises a mechanism which translates said outer ring to adjust the width of said annular extrusion orifice;
• and
• a positioning device which positions said outer ring and said mandrel relative to each other.

An extrusion die for extruding biodegradable material, said extrusion die comprising:

• a mandrel;
• an outer member positioned near said mandrel defining an extrusion orifice between said mandrel and said outer member;
• a mounting plate having a flow bore which conducts biodegradable material toward said extrusion orifice, wherein said mandrel is fixedly mounted to said mounting plate and said outer member is movably mounted to said mounting plate;
• a member which moves said outer member relative to said mandrel in a direction having a component transverse to an extrusion direction of biodegradable material through the extrusion orifice;
• a flow control device which controls flow of biodegradable material through the extrusion die, wherein said flow control device comprises a flow control channel upstream of the extrusion orifice, wherein the flow control channel throttles flow of the biodegradable material through the die, wherein said mandrel is attached to said mounting plate with at least one spacer between, wherein said mounting plate and said mandrel define said flow control channel;
• and
• a positioning device which positions said outer member and said mandrel relative to each other, wherein said positioning device comprises a shifting device for moving the outer member and the mandrel relative to each other and a fixing device which fixes the relative positions of said outer member and said mandrel.

An improved process for the extrusion of biodegradable material wherein said extrusion comprises flowing the biodegradable material in a flow direction through an orifice, said improvement comprising:

• moving the biodegradable material in a direction having a component transverse to the flow direction during extrusion;
• controlling the flow rate of biodegradable material through the extrusion die during extrusion, wherein said controlling comprises adjusting the head pressure of the biodegradable material in the extrusion die and adjusting at least one cross-sectional area of a biodegradable material flow path within the extrusion die;
• and
• modifying the orifice geometry.

A process for manufacturing biodegradable shaped products of increased strength, said process comprising:

• extruding a biodegradable material, wherein said extruding comprises moving the biodegradable material in a first direction through an orifice to produce an extrudate;
• modifying the orifice geometry;
• moving the biodegradable material in a second direction having a component transverse to the first direction during said extruding;
• controlling the flow rate of biodegradable material through the extrusion die during said extruding, wherein said controlling comprises adjusting the cross-sectional area of an extrusion orifice and wherein said controlling further comprises adjusting the cross-sectional area of a biodegradable material flow path at a location upstream of the extrusion orifice;
• compressing the extrudate;
• and
• molding the compressed extrudate of biodegradable material into a product.