US3782870A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for extruding a partially foamed thermoplastic product
Assignee: Oerlikon Barmag AG
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Filing: 1972-02-24
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Granted: 1974-01-01
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Expires: 1992-02-24
Abstract
Abstract Process and apparatus for producing a partially foamed thermoplastic polymer product in a single screw extruder by dividing an initial melt stream of the polymer into separate partial melt streams conveyed individually by the extruder to a shaping or forming die, uniformly mixing a foaming agent with at least one but not all of the separate and individually conveyed partial melt streams, and then rejoining all of said melt streams in the die in abutting core and shell layers with foaming of at least one but not all of said layers.
Inventors
- 👤 H Schippers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:29
CPC Classifications
B; B29; B29C; B29C44/00; B29C44/20; B29C44/22; B29C44/34; B29C44/36; B29C44/46; B29C44/50; B29C44/507; B29C48/00; B29C48/25; B29C48/36; B29C48/50; B29C48/74; B29C48/745; B29C45/00; B29C48/03; B29K; B29K2105/00; B29K2105/04; B29K2105/043; Y; Y10; Y10S; Y10S264/00; Y10S264/05
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
22 words
Apparatus as claimed in claim 1 wherein said by-pass conduit is connected as an external pipe line with respect to the screw.
Claim 2
Dependent Claim
26 words
Apparatus as claimed in claim 1 wherein said by-pass conduit is connected as a fluid line running through the cylindrical casing wall of the screw extruder.
Claim 3
Dependent Claim
25 words
Apparatus as claimed in claim 1 wherein said by-pass conduit is constructed as a tubular delivery pipe arranged outside the cylindrical casing of the extruder.
Claim 4
Dependent Claim
35 words
Apparatus as claimed in claim 1 wherein said inlet means to introduce the foaming agent is in fluid connection with said second screw conveying stage to enter laterally through the cylindrical casing of the extruder.
Claim 5
Dependent Claim
46 words
Apparatus as claimed in claim 1 wherein said rotatable screw is hollow with said inlet means to introduce the foaming agent being in fluid connection with said second screw conveying stage through a pipe line extending axially of the rotatable screw from the feed end thereof.
Claim 6
Dependent Claim
29 words
Apparatus as claimed in claim 6 wherein a stationary displacement body is mounted to extend axially into a hollow melt channel at the discharge end of the rotatable screw.
Claim 7
Dependent Claim
61 words
Apparatus as claimed in claim 1 wherein said rotatable screw is hollow to provide an inner channel for the melt containing the foaming agent, said channel being open at the discharge end of the screw while also being in fluid connection with said first screw conveying stage by means of radially directed bores through the core wall of the hollow screw.
Claim 8
Dependent Claim
20 words
Apparatus as claimed in claim 8 wherein a stationary displacement body is mounted to extend axially into said inner channel.
Claim 9
Dependent Claim
27 words
Apparatus as claimed in claim 9 wherein said stationary displacement body is an expeller means to discharge melt from said inner Channel into said extrusion die means.
Claim 10
Dependent Claim
22 words
Apparatus as claimed in claim 9 wherein said stationary displacement body contains radially projecting pins on its outer surface as mixing elements.
Claim 11
Dependent Claim
21 words
Apparatus as claimed in claim 8 wherein a static mixing element is mounted within said inner channel of the hollow screw.
Claim 12
Dependent Claim
22 words
Apparatus as claimed in claim 1 wherein said screw at its discharge end contains a dynamic mixing means rotating with the screw.
Claim 13
Dependent Claim
24 words
Apparatus as claimed in claim 1 including valve regulating means to control the melt flow and pressure in each of said partial melt streams.
Claim 14
Dependent Claim
24 words
Apparatus as claimed in claim 1 including a static mixing means arranged between the discharge end of the screw and said extrusion die means.
Claim 15
Dependent Claim
68 words
Apparatus as claimed in claim 1 wherein said rotatable screw is hollow to provide an inner channel in which there is mounted a static mixing means for a melt containing said foaming agent, said second screw conveying stage including a compression bead intermediate the length of said second stage with radially transverse bores in the wall of the hollow screw both immediately before and immediately after said bead.
Claim 16
Dependent Claim
15 words
Apparatus as claimed in claim 2 wherein said by-pass conduit contains a static mixing means.
Claim 17
Dependent Claim
26 words
Apparatus as claimed in claim 1 wherein said by-pass conduit is branched for fluid connection with two different concentric extrusion openings of the extrusion die means.
Claim 18
Dependent Claim
25 words
Apparatus as claimed in claim 1 including heating means for said by-pass conduit to control the temperature of melt delivered to said extrusion die means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-31 | 1977-07-02 | 1978-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-31 | 1981-07-02 | 1982-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-31 | 1985-07-02 | 1986-01-01 | $7700.00 | Window Closed / Lapsed |