Apparatus for making threaded articles in a plastic injection molding process

A rotatable core for use in an apparatus for making plastic articles by a plastic injection molding process, the rotatable core comprising:

• a lower stock portion and a top core portion;
• the rotatable core having a longitudinal hollow passageway extending generally from a lower end of the lower stock portion to an upper end of the top core portion for the passage of cooling fluid through a bubbler sleeve inside said hollow passageway;
• the lower end of the lower stock portion further comprising a replaceable stock water-seal insert portion at its lower end;
• and
• the top core portion further comprising gear means at an intermediate location on its outside surface for engaging a geared rack, which causes the rotation of the rotatable core.

A rotatable core for use in an apparatus for making plastic articles by a plastic injection molding process, the rotatable core comprising:

• a lower stock portion, an intermediate stock portion and a top core portion;
• the rotatable core having a longitudinal hollow passageway extending generally from a lower end of the lower stock portion, through the intermediate stock portion to an upper end of the top core portion for the passage of cooling fluid through a bubbler sleeve inside said hollow passageway;
• the lower end of the lower stock portion further comprising a replaceable stock water-seal insert portion at its lower end;
• the intermediate stock portion further comprising gear means at an intermediate location on its outside surface for engaging a geared rack which causes the rotation of the rotatable core;
• and
• the top core portion having means for removing said top core portion from the intermediate stock portion for replacement of said top core portion.

A timed advance assembly for relieving clamping pressure on a tapered shutoff surface of rotatable cores in a plastic injection molding process for making threaded articles, the timed advance assembly, in relation to each Bi-directional rack, comprising:

• two timed advance assemblies, each including a timed advance pneumatic piston assembly serving as means adapted for pushing a stripper plate away from a stationary plate in time with a thread pitch of the threaded articles as said threaded articles are being unscrewed from a threaded portion of rotatable cores used in the molding process;
• means for cooperative engagement of the two timed advance assemblies with first and second pinion gear assemblies and idler gears;
• the pinion gear assemblies being engageable to both the timed advance assemblies and the idler gears, the idler gears being engageable with the pinion gear assemblies, the idler gears and pinion gear assemblies being spaced so that when the first pinion gear assembly is engaged with a Bi-directional rack used in the molding process, the second pinion gear assembly is not engageable with the Bi-directional rack,
• wherein during a forward stroke of the Bi-directional rack, the second pinion gear assembly turns at idle, as the Bi-directional rack moves sideways to an alternate position, it disengages from the first pinion gear assembly and engages the second pinion gear assembly, and during the reverse stroke of the Bi-directional rack, the first pinion gear assembly turns at idle,
• wherein the first timed advance piston assembly is also engageable with an upper gear of the first pinion gear assembly,
• wherein while the Bi-directional rack is turning the first pinion gear assembly during its forward stroke, the upper gear of the first pinion gear assembly is engageable with the timed advance assembly and rotates it, wherein a rotatable core which is externally threaded is allowed to advance within an internally threaded bushing,
• wherein the advancing of the externally threaded rotatable core allows a primary pneumatic piston to advance forward and push the stripper plate up in time with the unscrewing molded part, and at the same time, the idler gears rotate the second pinion gear assembly in the opposite direction,
• wherein the second pinion gear rotates the second timed advance assembly in the opposite direction to allow the externally threaded rotatable core to retract within the internally threaded bushing, and
• wherein at the end of the Bi-directional rack's forward stroke, the retracted externally threaded core is down and in position to control a second primary pneumatic piston to advance forward during the reverse stroke of the Bi-directional rack.

A Bi-directional rack assembly for use in plastic molding processes for making plastic articles, the assembly comprising:

• a crosshead assembly;
• a plurality of spaced-apart parallel Bi-directional rack assemblies engaged at one end with the crosshead assembly with retainer means for retaining said one end within the crosshead assembly;
• each Bi-directional rack assembly comprising an elongate longitudinal rack having pitched gear teeth on opposite sides of each rack, said gear teeth adapted for operative engagement with mating gear teeth on adjacent columns of spaced-apart rotatable cores when said rack is used in operative engagement with a mold;
• an upper actuating bar and a lower actuating bar in cooperative horizontal side-to-side engagement with respective upper and bottom sides of each rack;
• and
• means for retaining said actuating bars in the crosshead assembly and in cooperative alignment with the rack.

A core stock water-seal insert portion for a rotatable core used in apparatus for making plastic articles by a plastic injection molding process, the stock water-seal insert portion comprising:

• a water-seal insert portion having means for attaching to a rotatable core portion for use in an apparatus for making plastic articles in a plastic injection molding process and for separating from said rotatable core portion for replacing said water-seal seal insert portion when desired;
• the water-seal insert portion further comprising a longitudinal hollow passageway extending generally from its lower end through its upper end for the passage of cooling fluid through a bubbler sleeve inside said hollow passageway;
• and
• the lower end of the water-seal insert portion having an inlet port adapted to be in fluid communication with a fluid cooling source and the bubbler sleeve.