Hot sprue valve assembly for an injection molding machine

Claim 2

In an injection molding machine for producing centrally apertured record discs, a valve assembly for controlling flow of molten disc-forming material through a sprue bushing into a disc-shaped mold cavity, comprising: valve means normally positioned in spaced relation with the sprue bushing and on a side of the mold cavity generally opposite the sprue bushing for allowing flow of the molten disc-forming material through the sprue bushing into the mold cavity, said valve means being movable through the mold cavity into bearing engagement with the sprue bushing for preventing flow of the molten disc-forming material through the sprue bushing into the mold cavity, said valve means including means for forming a central aperture in the record disc formed within the mold cavity and for ejecting from the machine the portion of the disc-forming material displaced from said central aperture upon at least partial solidification of said portion.

Claim 3

The valve assembly of claim 1 wherein the sprue bushing has a generally cylindrical shape and defines a flow path for the molten disc-forming material, said valve means including a cylindrical sleeve valve for movement through the mold cavity into bearing engagement with the sprue bushing annularly about the flow path in the sprue bushing for preventing flow of the molten disc-forming material from the flow path into the mold cavity.

Claim 4

The valve assembly of claim 1 wherein said valve means comprises: a stationary cylindrical valve guide positioned in spaced relation with the sprue bushing on the side of the mold cavity generally opposite the sprue bushing; a sleeve valve concentrically received about said valve guide for movement between a first position spaced from the sprue bushing to allow flow of the molten disc-forming material through the sprue bushing and into the mold cavity, and a second position projecting through the mold cavity into bearing engagement with the sprue bushing to prevent flow of the molten disc-forming material through the sprue bushing and into the mold cavity, said sleeve valve being movable to said second position prior to solidification of the disc-forming material to mold an aperture in the record disc formed in the mold cavity; and an ejector pin carried concentrically within said valve guide for movement along its own axis between a position retracted from the mold cavity when said sleeve valve is moved to said second position for cooperating with said valve guide to define a relatively small recess to accommodate disc-forming material displaced by said sleeve valve, and a position advanced toward the mold cavity after at least partial solidification of said portion of the disc-forming material displaced from said aperture to eject said portion from the machine.

Claim 5

The valve assembly of claim 1 wherein the sprue bushing has. a generally cylindrical shape and defines a flow path for the molten disc-forming material, said valve means comprising an ejector valve pin for movement through the mold cavity to a seated position upon the sprue bushing to close the sprue bushing flow path and thereby prevent flow of molten disc-forming material into the mold cavity.

Claim 6

The valve assembly of claim 4 wherein the sprue bushing flow path is oriented generally at a right angle to the plane of the disc-forming mold cavity and communicates with the mold cavity generally at the central axis thereof, said ejector valve pin being oriented for movement toward and away from the sprue bushing substantially along its own axis and substantially along the axis of the sprue bushing flow path, said ejector valve pin including at one end a valve head shaped for seating engagement with the sprue bushing to close the sprue bushing flow path.

Claim 7

The valve assembly of claim 4 wherein said means for forming said aperture in the disc comprises a sleeve punch concentrically carried about said ejector valve pin for movement along the axis thereof toward and away from the mold cavity, said sleeve punch including a punch head for movement into and through the mold cavity after solidification of the disc-forming material therein for punching said aperture in the disc, said sleeve punch being movable to a retracted position when said ejector valve pin is positioned to allow flow of the molten disc-forming material into the mold cavity and prior to solidification of the disc-forming material.

Claim 8

The valve assembly of claim 6 wherein the machine includes first and second mold halves movable between a closed position to define the mold cavity and an open position to allow extraction of a molded disc from the molded cavity, said valve assembly and the sprue bushing being carried respectively by said first and second mold halves, and wherein said ejector valve pin is movable from a retracted position spaced from the sprue bushing when said mold halves are in said closed position to allow flow of the molten disc-forming material into the mold cavity to a first advanced position in bearing engagement with the sprue bushing to prevent further flow of the disc-forming material into the mold cavity, and to a second and further advanced position when said mold halves are in said open position to eject said portion of the disc-forming material displaced from said aperture by said sleeve punch.

Claim 9

The valve assembly of claim 1 wherein said valve means comprises: an ejector valve pin mounted on the side of the mold cavity opposite the sprue bushing, said valve pin being movable along its own axis between a retracted position spaced from the sprue bushing to allow the molten disc forming material to flow through the sprue bushing into the mold cavity, and an advanced first position extending through the mold cavity into bearing engagement with the sprue bushing to close the sprue bushing to further flow of the molten disc-forming material into the mold cavity; and a sleeve punch concentrically carried about said ejector valve pin for movement along the axis thereof toward and away from the mold cavity, said sleeve punch including a punch head for movement into and through the mold cavity after solidification of the disc-forming material therein for punching said aperture in the disc, said sleeve punch being movable to a retracted position when said ejector valve pin is positioned to allow flow of the molten disc-forming material into the mold cavity and prior to solidification of the disc-forming material; said ejector valve pin being movable to a second and further advanced position subsequent to formation of said aperture by said sleeve punch to eject from the machine said portion of the disc-forming material displaced from said aperture.

Claim 10

A mold assembly for an injection molding machine, comprising: first and second mold halves movable toward each other to define a disc-shaped mold cavity, and movable away from each other to allow a molded disc to be removed from said mold cavity; a sprue bushing defining a flow path for passage of molten disc-forming material into said mold cavity in a direction generally normal to the plane of said mold cavity and generally along the central axis of said mold cavity; and a sprue valve assembly positioned on the side of said mold cavity generally opposite said sprue bushing and including valve means movable between an open position spaced from said sprue bushing to allow the molten disc-forming material to pass into said mold cavity and a closed position extending through said mold cavity in engagement with said sprue bushing to prevent the molten disc-forming material from flowing into said mold cavity, said valve assembly further including means for forming a central aperture in the molded disc within said mold cavity, and for ejecting the portion of the disc-forming material with said aperture from the machine when said first and second mold halves are moved away from each other.

Claim 11

A mold assembly for an injection molding machine, comprising: first and second mold halves movable toward each other to define a disc-shaped mold cavity, and movable away from each other to allow a molded disc to be removed from said mold cavity; a sprue bushing defining a flow path for passage of molten disc-forming material into said mold cavity in a direction generally normal to the plane of said mold cavity and generally along the central axis of said mold cavity; and a sprue valve assembly positioned on the side of said mold cavity generally opposite said sprue bushing and including valve means movable between an open position spaced from said sprue bushing to allow the molten disc-forming material to pass into said mold cavity and a closed position extending through said mold cavity in engagement with said sprue bushing to prevent the molten disc-forming material from flowing into said mold cavity, said valve assembly further including means for forming a central aperture in the molded disc within said mold cavity, and for ejecting the portion of the disc-forming material with said aperture from the machine when said first and second mold halves are moved away from each other.

Claim 12

The mold assembly of claim 9 wherein said valve means comprises: a stationary cylindrical valve guide positioned in spaced relation with the sprue bushing on the side of the mold cavity generally opposite the sprue bushing; a sleeve valve concentrically received about said valve guide for movement between a first position spaced from the sprue bushing to allow flow of the molten disc-forming material through the sprue bushing and into the mold cavity, and a second position projecting through the mold cavity into bearing engagement with the sprue bushing to prevent flow of the molten disc-forming material through the sprue bushing and into the mold cavity, said sleeve valve being movable to said second position prior to solidification of the disc-forming material to mold an aperture in the record disc formed in the mold cavity; and an ejector pin carried concentrically within said valve guide for movement along its own axis between a position retracted from the mold cavity when said sleeve valve is moved to said second position for cooperating with said valve guide to define a relatively small recess to accommodate disc-forming material displaced by said sleeve valve, and a position advanced toward the mold cavity after at least partial solidification of said portion of the disc-forming material displaced from said aperture to eject said portion from the machine.

Claim 13

In an injection molding machine for producing centrally apertured record discs, said machine including a generally disc-shaped mold cavity and a sprue bushing for flow of molten disc-forming material into the mold cavity, a method of controlling flow of the disc-forming material into the mold cavity comprising the steps of: positioning valve means in a normal position in spaced relation with the sprue bushing on the side of the mold cavity opposite the sprue bushing for allowing flow of the molten disc-forming material through the sprue bushing into the mold cavity; moving the valve means through the mold cavity into bearing engagement with the sprue bushing to prevent flow of the molten disc-forming material through the sprue bushing into the mold cavity when the mold cavity is filled; forming an aperture in the record disc formed in the mold cavity; and ejecting from the machine the portion of the disc-forming material displaced from the aperture upon at least partial solidification of said portion.

Claim 14

In an injection molding machine for producing centrally apertured record discs, said machine including a generally disc-shaped mold cavity and a sprue bushing for flow of molten disc-forming material into the mold cavity, a method of controlling flow of the disc-forming material into the mold cavity comprising the steps of: positioning valve means in a normal position in spaced relation with the sprue bushing on the side of the mold cavity opposite the sprue bushing for allowing flow of the molten disc-forming material through the sprue bushing into the mold cavity; moving the valve means through the mold cavity into bearing engagement with the sprue bushing to prevent flow of the molten disc-forming material through the sprue bushing into the mold cavity when the mold cavity is filled; forming an aperture in the record disc formed in the mold cavity; and ejecting from the machine the portion of the disc-forming material displaced from the aperture upon at least partial solidification of said portion.

Claim 15

In an injection molding machine for producing centrally apertured record discs, said machine including a generally disc-shaped mold cavity and a sprue bushing for flow of molten disc-forming material into the mold cavity, a method of controlling flow of the disc-forming material into the mold cavity comprising the steps of: positioning a sleeve valve in a normal position in spaced relation with the sprue bushing on the side of the mold cavity opposite the sprue bushing for allowing flow of the molten disc-forming material through the sprue bushing into the mold cavity; positioning an ejector pin concentrically within the sleeve valve in a normal position advanced toward the mold cavity; moving the sleeve valve through the mold cavity prior to solidification of the disc-forming material therein into bearing engagement with the sprue bushing to prevent further flow of molten disc-forming material through the sprue bushing into the mold cavity and to mold an aperture in the record disc formed in the mold cavity; substantially simultaneously retracting the ejector pin from the mold cavity to accommodate disc-forming material displaced by the sleeve valve; returning the ejector pin to its normal position to eject from the machine the portion of the disc-forming material displaced from the aperture; and returning the sleeve valve to its normal position.

Claim 16

In an injection molding machine for producing centrally apertured record discs, said machine including a generally disc-shaped mold cavity and a sprue bushing for flow of molten disc-forming material into the mold cavity, a method of controlling flow of the disc-forming material into the mold cavity comprising the steps of: positioning a sleeve valve in a normal position in spaced relation with the sprue bushing on the side of the mold cavity opposite the sprue bushing for allowing flow of the molten disc-forming material through the sprue bushing into the mold cavity; positioning an ejector pin concentrically within the sleeve valve in a normal position advanced toward the mold cavity; moving the sleeve valve through the mold cavity prior to solidification of the disc-forming material therein into bearing engagement with the sprue bushing to prevent further flow of molten disc-forming material through the sprue bushing into the mold cavity and to mold an aperture in the record disc formed in the mold cavity; substantially simultaneously retracting the ejector pin from the mold cavity to accommodate disc-forming material displaced by the sleeve valve; returning the ejector pin to its normal position to eject from the machine the portion of the disc-forming material displaced from the aperture; and returning the sleeve valve to its normal position.

Claim 17

In an injection molding machine for producing centrally apertured record discs, said machine including a generally disc-shaped mold cavity and a sprue bushing for flow of molten disc-forming material into the mold cavity, a method of controlling flow of the disc-forming material into the mold cavity comprising the steps of: positioning an ejector valve pin in a normal position in spaced relation with the sprue bushing and on the side of the mold cavity opposite the sprue bushing for allowing flow of molten disc-forming material into the mold cavity; positioning a sleeve punch concentrically about the ejector valve pin in a normal position on the side of the mold cavity opposite the sprue bushing; advancing the ejector valve pin through the mold cavity prior to solidification of the disc-forming material therein into bearing engagement with the sprue bushing to prevent further flow of molten disc-forming material through the sprue bushing into the mold cavity; allowing the disc-forming material within the mold cavity to solidify; withdrawing the sprue bushing in a direction away from the mold cavity; advancing the sleeve punch into and through the mold cavity to punch an aperture in the solidified disc; advancing the ejector valve pin to a further advanced position to dislodge from the punch the portion of the disc-forming material displaced from the aperture; and returning the sleeve punch and the ejector valve pin to their normal positions.

Claim 18

In an injection molding machine for producing centrally apertured record discs, said machine including a generally disc-shaped mold cavity and a sprue bushing for flow of molten disc-forming material into the mold cavity, a method of controlling flow of the disc-forming material into the mold cavity comprising the steps of: positioning an ejector valve pin in a normal position in spaced relation with the sprue bushing and on the side of the mold cavity opposite the sprue bushing for allowing flow of molten disc-forming material into the mold cavity; positioning a sleeve punch concentrically about the ejector valve pin in a normal position on the side of the mold cavity opposite the sprue bushing; advancing the ejector valve pin through the mold cavity prior to solidification of the disc-forming material therein into bearing engagement with the sprue bushing to prevent further flow of molten disc-forming material through the sprue bushing into the mold cavity; allowing the disc-forming material within the mold cavity to solidify; withdrawing the sprue bushing in a direction away from the mold cavity; advancing the sleeve punch into and through the mold cavity to punch an aperture in the solidified disc; advancing the ejector valve pin to a further advanced position to dislodge from the punch the portion of the disc-forming material displaced from the aperture; and returning the sleeve punch and the ejector valve pin to their normal positions.