Foam sheet extrusion die apparatus, and system with adjustable choke area

An extruder die apparatus for the extrusion of a thermoplastic material, which die apparatus has an adjustable choke area, which apparatus comprises:

• a) an extruder housing having an axial bore for the extrusion of thermoplastic material therethrough from the inlet to the outlet of the bore;
• b) an inner die lip and an outer die lip about the bore and within the housing and each having a one and the other end, the one end of the inner and outer die lip having a concentric die gap for the extrusion of a thermoplastic material, the inner and outer die lips forming a thermoplastic material extrusion flow passageway from the one to the other end of the die;
• c) a peripheral choke gap within said thermoplastic material flow passageway with a restricted, cross-section, thermoplastic material flow area;
• d) a generally axially aligned concentric slot in the outer die lip having an open end generally adjacent to the choke gap;
• e) a choke ring means slidably movably positioned within said slot and having a selected clearance position within the slot and having a curved, axially aligned face surface section adapted to extend from the open end of the slot into the choke gap and adapted to move between a non-restrictive position out of the choke gap and a restrictive position in the choke gap;
• f) the choke ring means having a plurality of generally uniformly spaced apart, peripheral, axial castellation elements within the slot;
• g) choke ring adjusting means about the outer periphery of the choke ring to include a plurality of spaced-apart axially eccentric bolts with bolt heads, the bolt heads having markings thereon to indicate the position of each bolt;
• and
• h) a plurality of generally uniform, spaced apart, oval holes in at least some of the castellation elements and choke ring adjusting means, and wherein said bolts of the choke ring adjusting means extend into a selected hole of the choke ring means, whereby on movement of each of the bolts, the choke ring means is axially adjusted and flexed in selected peripheral sections to permit the individual adjustment of the cross sectional area of the choke gap.

A thermoplastic extruder die apparatus for the extrusion of a thermoplastic material and having a choke gap and having an axial peripheral slot in the thermoplastic die apparatus for separate, peripheral adjustment of the choke gap of the extruder apparatus, in the extrusion of thermoplastic material, and which choke ring comprises:

• a) a curved, axially aligned face surface section adapted to extend from the open end of the slot into the choke gap, and to face the direction of extrusion of the thermoplastic material;
• b) a plurality of generally uniformly spaced apart, peripheral, axial castellation elements within the slot;
• and
• c) a plurality of generally uniform, spaced apart oval holes in at least some of the castellation elements to receive eccentric bolts of an axial choke ring adjusting means whereby on rotatory movement of each of the (bolts), axial adjusting of the choke ring means occurs in each section of the choke gap, and choke ring adjusting means to provide for the adjustment of the choke ring means in various sections of the choke gap.