US3746492A — Apparatus for molding foamed thermoplastic articl…

Claim 1

Independent Claim 171 words

An apparatus for molding foamed thermoplastic articles comprising accumulation means including an expansible and contractable chamber for receiving a predetermined amount of a mixture of thermoplastic material and blowing agent therein, means for heating thermoplastic material and for mixing the thermoplastic material and a blowing agent and for conveying the resulting mixture under a first pressure sufficient to preclude the premature foaming thereof into said expansible and contractable chamber in said accumulation means, mold means connected to said accumulation means for receiving the mixture of thermoplastic material and blowing agent from said accumulation means under conditions of reduced pressure to permit the foaming of the mixture received therein, and means connected to said accumulation means for applying an expansion resisting pressure to said chamber during the receipt of the mixture therein to maintain the mixture under said first pressure in said chamber, and for applying a contracting pressure considerably higher than said expansion resisting pressure to said chamber to rapidly discharge the mixture from the accumulation means into said mold means.

Claim 2

Independent Claim 171 words

An apparatus for molding foamed thermoplastic articles comprising accumulation means including an expansible and contractable chamber for receiving a predetermined amount of a mixture of thermoplastic material and blowing agent therein, means for heating thermoplastic material and for mixing the thermoplastic material and a blowing agent and for conveying the resulting mixture under a first pressure sufficient to preclude the premature foaming thereof into said expansible and contractable chamber in said accumulation means, mold means connected to said accumulation means for receiving the mixture of thermoplastic material and blowing agent from said accumulation means under conditions of reduced pressure to permit the foaming of the mixture received therein, and means connected to said accumulation means for applying an expansion resisting pressure to said chamber during the receipt of the mixture therein to maintain the mixture under said first pressure in said chamber, and for applying a contracting pressure considerably higher than said expansion resisting pressure to said chamber to rapidly discharge the mixture from the accumulation means into said mold means.

Claim 3

Dependent Claim 87 words

The apparatus as defined in claim 1, wherein said expansible and contractable chamber includes a piston translatable between a first position defining an unexpanded chamber and a second position defining an expanded chamber, and wherein said means for applying pressure to said chamber applies a first force on said piston resisting movement of said piston from said first to said second position and selectively applies a second force of greater intensity than said first force for moVing said piston from said second position to said first position.

Claim 4

Dependent Claim 91 words

The apparatus as defined in claim 2 wherein said pressure applying means continuously applies said second force to said piston during both the receipt and discharge of the mixture into and from said chamber and includes means for selectively applying force to said piston in opposition to said second force during the receipt of material into said chamber, said opposition force being of less value than said second force so that said first force applied to the piston is a resultant force defined by said second force less said opposition force.

Claim 5

Dependent Claim 31 words

The apparatus as defined in claim 2 including means for establishing communication between said accumulation means and said mold means substantially concurrently upon application of said contracting pressure to said chamber.

Claim 6

Independent Claim 176 words

An apparatus for molding foamed thermoplastic articles comprising accumulation means including a plurality of expansible and contractable chambers for receiving a predetermined amount of a mixture of thermoplastic material and blowing agent therein, means for heating thermoplastic material and for mixing the thermoplastic material and a blowing agent and for conveying the resulting mixture under a first pressure sufficient to preclude the premature foaming thereof into each of said expansible and contractable chambers in said accumulation means, mold means connected to each of said chambers in said accumulation means for receiving the mixture of thermoplastic material and blowing agent from said accumulation means under conditions of reduced pressure to permit the foaming of the mixture received therein, and means connected to said accumulation means for applying an expansion resisting pressure to each of said chambers during the receipt of the mixture therein to maintain the mixture under said first pressure in said chamber, and for applying a contracting pressure to said chamber to rapidly discharge the mixture from each of said chambers into said mold means.

Claim 7

Independent Claim 176 words

An apparatus for molding foamed thermoplastic articles comprising accumulation means including a plurality of expansible and contractable chambers for receiving a predetermined amount of a mixture of thermoplastic material and blowing agent therein, means for heating thermoplastic material and for mixing the thermoplastic material and a blowing agent and for conveying the resulting mixture under a first pressure sufficient to preclude the premature foaming thereof into each of said expansible and contractable chambers in said accumulation means, mold means connected to each of said chambers in said accumulation means for receiving the mixture of thermoplastic material and blowing agent from said accumulation means under conditions of reduced pressure to permit the foaming of the mixture received therein, and means connected to said accumulation means for applying an expansion resisting pressure to each of said chambers during the receipt of the mixture therein to maintain the mixture under said first pressure in said chamber, and for applying a contracting pressure to said chamber to rapidly discharge the mixture from each of said chambers into said mold means.

Claim 8

Dependent Claim 133 words

The apparatus as defined in claim 2 wherein said piston is translatable between a lowered position defining an unexpanded chamber and a raised position defining an expanded chamber, said means for applying said first and second forces on said piston comprises first pressure means for urging said piston from its raised position to its lowered position to apply said second force through said piston to said mixture, second pressure means of a value less than said first pressure means for urging said piston from its lowered position to its raised position in opposition to said first pressure means to apply said first force through said piston to said mixture when acting in concert with said first pressure means, and means for selectively releasing said second pressure means while maintaining said first pressure means.

Claim 9

Dependent Claim 34 words

The apparatus as defined in claim 6 further including means for adjusting the raised position of said piston whereby the volume of the mixture adapted to be received in said chamber may be varied.

Claim 10

Dependent Claim 62 words

The apparatus as defined in claim 5 including means for establishing communication between each of said chambers and said mold means comprising an independent line extending from each accumulation chamber and terminating in an injection port, and means for independently terminating communication through each of said independent lines upon the associated accumulation chamber being exhausted of its predetermined amount of the mixture.

Claim 11

Dependent Claim 28 words

The apparatus as defined in claim 8 wherein said mold means comprises a single cavity, and each of said injection ports communicates with said cavity at spaced locations.

Claim 12

Dependent Claim 31 words

The apparatus as defined in claim 8 wherein said mold means comprises a plurality of separate cavities, and each of said injection ports communicates with a separate one of said cavities.

Claim 13

Dependent Claim 69 words

The apparatus as defined in claim 8 wherein each of said accumulation chambers includes a translatable piston and said means for maintaining the received mixture under pressure and for forcing the mixture from each of said accumulation chambers includes means for applying a first force on each of said pistons and for selectively applying a second force of greater intensity than said first force on each of said pistons.

Claim 14

Dependent Claim 35 words

The apparatus as defined in claim 11 further including means for independently adjusting at least one of the limits of translation for each piston whereby the volume of the accumulation chambers may be independently varied.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1976-07-16	1977-01-15	1977-07-17	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1980-07-16	1981-01-15	1981-07-17	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1984-07-16	1985-01-15	1985-07-17	$7700.00	Window Closed / Lapsed

Apparatus for molding foamed thermoplastic articles

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