Devices and methods for maximizing purge effectiveness for molding machines
OwnerJoel Thomsoninventor
Life of this patent
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Abstract
Methods and devices for cleaning the screw and barrel of a reciprocating screw injection molding machine using a purging/cleaning compound and a non-return valve that can be held open during the purging/cleaning cycle to allow bi-directional flow of the purging/cleaning compound.
Claims21
An apparatus for a reciprocating screw injection molding machinery having a barrel and a screw which rotates in the barrel comprising:
- a check valve having means to selectively switch to a first mode which allows bi-directional flow of material along the screw.
A method of allowing bi-directional flow in reciprocating screw injection molding machines having a barrel and screw which rotates in the barrel comprising the steps of:
- moving the screw in a rotational direction to allow material to flow in a first axial direction;
- moving the screw in a second axial direction to lock a check valve;
- moving the screw in the first axial direction to cause the material to flow in the second axial direction;
- and
- moving the screw in the rotational direction to unlock the check valve and allow material to flow in the first axial direction.
A method of cleaning reciprocating screw injection molding machines having a barrel and screw which rotates in the barrel comprising the steps of:
- displacing residual melt in screw flights of the screw with a cleaning compound;
- accumulating a quantity of the cleaning compound ahead of the screw;
- blocking an exit for the cleaning compound from the barrel;
- moving the screw in a forward axial motion to cause the cleaning compound to travel back into the screw flights;
- at least partially opening the exit;
- and
- expelling the cleaning compound.
Dependencies are inferred from the claim text.