Method and apparatus for individual control of injection mold shut-off bushings

• US 4,279,582 A
• Filed: 04/02/1979
• Issued: 07/21/1981
• Est. Priority Date: 04/02/1979
• Status: Expired due to Term

• Current Assignee: Incoe Corporation
• Original Assignee: Incoe Corporation
• Inventors: Osuna-Diaz, Jesus M.
• Primary Examiner(s): Pavelko, Thomas P.
• Application Number:
  US06/026,607
• Time in Patent Office: 841 Days
• Field of Search: 425/564-566, 425/DIG. 229, 425/159, 425/160, 425/549, 425/570, 425/573, 425/166, 264/328.8
• US Class Current: 425/159
• CPC Class Codes: B29C 2045/2817 Several valve pin drive cylinders connected to the fluid distributor
• CPC Class Codes: B29C 2045/2848 having an adjustable stroke length
• CPC Class Codes: B29C 45/281 Drive means therefor

Abstract

A method and apparatus for multiple cavity injection molding which permits individual variation of gate opening time for mold shut-off bushings. The gate pins for the shut-off bushings are controlled by individual double-acting fluid motor, the bushings being fed by a common manifold. Gate opening is thus not dependent upon attainment of a predetermined injection pressure. Closure of the gate for each cavity will permit material to be fed faster to the other cavities. Novel means is provided for securing each gate pin to its actuating cylinder, which minimizes heat transfer to the motor, accommodates expansion of the material manifold and permits gate opening adjustment. The fluid motors are end-mounted on an actuating fluid manifold, allowing close juxtaposition. A cycle counter may be used to control inventory.

Claims

1. In combination, a pair of mold dies movable between open and closed positions, a plurality of shut-off bushings carried by one of said mold dies, a material manifold having a single entry for connection to a molding machine and having passages leading to said shut-off bushings, a gate pin slidably mounted in each shut-off bushing, means responsive to closure of said mold dies to simultaneously move all said gate pins to their open position, individual motor means for advancing each pin to a closed position independently of the other pins, whereby material from said single source will be delivered to the remaining open gates, and means opening said molds after all gates have been closed, said motor means each comprising a hollow piston rod, said gate pin extending through said piston rod and being secured thereto at its rearward end, the remainder of said gate pin within said piston rod being spaced inwardly therefrom to provide a heat insulating gap which also accommodates relative lateral shifting between the gate pin and piston rod.

2. In a mold die assembly of the type having a pair of mold dies movable between open and closed positions, a plurality of shut-off bushings carried by one of said mold dies, a material manifold having a single entry for connection to a molding machine and having passages leading to said shut-off bushings, a gate pin slidably mounted in each shut-off bushing, means responsive to closure of said mold dies to individually move all said gate pins to their open position, individual motor means for advancing each pin to a closed position independently of the other pins whereby material from said single source will be delivered to any remaining open gates, and means opening said molds after all gates have been closed, the improvement wherein said motor means each has a hollow piston rod, each gate pin extends through its respective piston rod and is secured thereto at its rearward end, and the remainder of said gate pins within said piston rods is spaced inwardly therefrom to provide heat insulating gaps which also accommodate relative lateral shifting between the gate pins and the piston rods.

3. In a plastic injection molding machine of the type having a pair of mold dies provided with cavity means and movable between open and closed positions, a plurality of shut-off bushings carried by said mold dies each having a gate through which melt material is discharged into said cavity means, a material manifold having a single entry for receiving melt from said machine and passages leading from said single entry through which melt material is delivered to said shut-off bushings, gate pins slidably mounted in said shut-off bushings movable to open or close said gates to control flow of melt material into said cavity means, actuator means for moving said gate pins in predetermined sequence to selectively open or close said gates whereby, upon closure of one or more of said gate pins, melt material is delivered to any remaining open gates, and means for opening said molds after all of said gates have been closed, the improvement wherein said pin actuator means comprises fluid motors having hollow piston rods;

wherein said gate pins extend through said piston rods and are secured thereto at the rearward ends thereof; and

wherein the portions of said pins ahead of their points of attachment to said piston rods are spaced inwardly from the latter to provide heat insulating gaps which also accommodate relative lateral shifting between said gate pins and said piston rods.

4. In a mold die assembly adapted for use with a plastic injection molding machine and of a type having cavity means therein and a plurality of gates communicating with said cavity means, means for delivering melt material simultaneously to said gates for injection into said cavity means, gate pins for selectively opening and closing said gates, and fluid motors having piston means forming gate pin actuators, the improvement comprising connecting means fastening rearward end portions of said gate pins to respective gate pin actuators, and means ahead of said connecting means providing radial clearances between the said piston means and adjacent portions of said gate pins, said clearances forming heat insulating gaps and also accommodating relative lateral shifting between said gate pins and said piston means.

5. In a mold die assembly adapted for use with a plastic injection molding machine and of a type having cavity means therein and a plurality of gates communicating with said cavity means, means for delivering melt material simultaneously to said gates for injection into said cavity means, gate pins for selectively opening and closing said gates, and fluid motors having piston means forming gate pin actuators, the improvement comprising means forming access openings in said fluid motors rearwardly of and in-line with said gate pins, and connecting means detachably fastening rearward end portions of said gate pins to respective gate pin actuators operable to permit adjustment of said gate pins longitudinally relative to said actuators and to permit removal of said gate pins rearwardly through the access openings of said fluid motors.

6. The invention as defined by claim 5 including an oil manifold connected to and carrying said fluid motors, said manifold having access openings in-line with said gate pins and with the access openings of said fluid motors, whereby said gate pins are removable not only through the access openings of said fluid motors but also through the access openings of said oil manifold.

7. The invention as defined by claim 5 including means ahead of said connecting means providing radial clearances between the said piston means and adjacent portions of said gate pins, said clearances forming heat insulating gaps and also accommodating relative lateral shifting between said gate pins and said piston means.

8. In a multi-cavity mold die assembly adapted for use with a plastic injection molding machine having a machine nozzle and wherein the mold die has a plurality of fluid-motor actuated gate pins, said fluid motors including advanceable and retractable pistons connected to said gate pins and forming gate pin actuators, and means connecting each of said gate pins to a respective one of said gate pin actuators operable to adjust said gate pins longitudinally relative to said actuators, the improvement wherein said fluid motors have access openings in-line with said gate pins, and including an oil manifold connected to and carrying said fluid motors, said manifold having access openings in-line with said gate pins and the access openings of said fluid motors, said means for adjustably connecting said gate pins to said gate pin actuators permitting removal of said gate pins rearwardly through the access openings of said fluid motors and of said oil manifold.