US3724985A Expired / Lapsed US ⏱️ 0.0 years remaining

Extruding apparatus

Assignee: Sherwood Medical Co

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Filing: 1971-01-18

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Granted: 1973-04-03

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Expires: 1991-01-18

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Abstract

Abstract An extruding apparatus for producing tubing having different characteristics, e.g. physical, chemical and the like, along its axial length including two or more molten plastic material producers that feed different molten materials to an extruding die, one molten plastic material producer being an injection molding machine or an extruder in combination with an accumulator injector. The two molten plastic producers are controlled so that when one producer is delivering molten material to the die producing a first section of the tubing, the other producer is either not injecting or exhausting to reclaimable waste. A selectively operable valve is provided for delivering the molten materials to the die from one of the two sources having a fast cut-off characteristic effected by providing the inlets to the valve, connected to each of the molten material sources, and the valve outlet, connected to the extruding die, on one diametral side of the valve to minimize the required valve movement in switching from one material source to the other. The valve is also provided with an exhaust for one of the inlets permitting that material to be reclaimed. Also provided in another embodiment is an extruding apparatus having two extruders that feed different molten plastic materials to a die, there being provided an accumulator-injector in each of the conduits interconnecting the extruders with the die arranged and controlled so that when one extruder is delivering molten material to the die producing a first section of tubing, the first accumulator-injector in the conduit connecting the other extruder with the die withdraws molten plastic from that conduit. Thereafter, the first accumulator-injector injects the previously withdrawn molten material into the die, eliminating waste, while the second accumulator-injector withdraws the molten material emanating from its associated extruder. This cycle is reversed periodically to produce a tube having sections of different material without requiring a valve for draining the molten material from one of the extruders while the other feeds the die.

Inventors

👤 N Burlis
👤 J Corbett

Bibliographic Details

Application Number —

Jurisdiction US

Data Source google_patents

Last Synchronized 2026-10-23 22:32

CPC Classifications

B; B29; B29C; B29C48/00; B29C48/25; B29C48/36; B29C48/49; B29C48/16; B29C48/18; B29C48/03; B29C48/09

Claims Analysis

Total Claims: 6

Claim 1

Independent Claim 170 words

An extruding apparatus, comprising: first extruder means for producing a first molten plastic extrudable material, second extruder means for producing a second molten plastic extrudable material, extruding die means receiving molten material from said first and second extruder means for producing a tubular extrudate having different characteristics along the length thereof, first means for conveying molten material from said first extruder means to said extruding die, second means for conveying molten material from said second extruder means to said extruding die, first accumulator-injector means communicating with said first conveying means for withdrawing molten material from said first conveying means while the second conveying means is delivering molten material to said extruding die and for thereafter injecting said molten material into said first conveying means, and second accumulator-injector means communicating with said second conveying means for withdrawing molten material from said second conveying means while the first conveying means is delivering said first molten material to said extruding die and for thereafter injecting said molten material into said second conveying means.

Claim 2

Dependent Claim 46 words

An extruding apparatus as defined in claim 2, including a valve in said first conveying means between the first accumulator-injector and the extruding die for preventing flow from the die into the first accumulator as the accumulator is withdrawing molten material from the first conveying means.

Claim 3

Dependent Claim 47 words

An extruding apparatus as defined in claim 3, including a second valve in said second conveying means between the second accumulator-injector and the extruding die for preventing flow from the die into the second accumulator as the accumulator is withdrawing molten material from the second conveying means.

Claim 4

Dependent Claim 47 words

An extruding apparatus as defined in claim 2, including means for supplying air to the extruder die, and means to regulate the flow of air to the extruder die so that upon a change from one material to the other a predetermined extrudate configuration will be produced.

Claim 5

Dependent Claim 119 words

An extruding apparatus, comprising; a source of first molten material, a source of second molten material, at least one of said sources being an injection device, a die for extruding the first and second molten materials, valve means for selectively delivering the molten materials to the die including first inlet means for one of said materials, second inlet means for the other of said materials, outlet means connected to said die, exhaust means, a rotatable valve member in said valve means for selectively connecting said first inlet means with said exhaust means or said outlet means, and for selectively connecting said second inlet means to said outlet means when said first inlet means is connected to said exhaust means.

Claim 6

Dependent Claim 28 words

An extruding apparatus as defined in claim 6, wherein said valve member prevents mixing of the molten material from said first inlet means and said second inlet means.

References Cited (Backward Citations)

US836083A Cited

GB354837A Cited

US3039141A Cited

US3143583A Cited

US3175247A Cited

US3526929A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1976-04-02	1976-10-02	1977-04-03	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1980-04-02	1980-10-02	1981-04-03	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1984-04-02	1984-10-02	1985-04-03	$7700.00	Window Closed / Lapsed

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