US3901958A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for forming foamed plastic articles
Assignee: Cellu Products Co Inc
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Filing: 1973-03-23
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Granted: 1975-08-26
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Expires: 1993-03-23
Abstract
Abstract A method and apparatus for forming foamed plastic articles wherein a heated foamable plastic material is extruded through an annular orifice to form a tubular parison, and the parison is then blow molded into a desired configuration. Provision is made for maintaining the parison under sufficient pressure to prevent the foaming of the plastic material during the extrusion and blow molding operations, and the pressure is then released to cause the foamable plastic material to foam. The resulting foam may completely fill the mold to form a solid article, or it may only partially fill the mold to form a hollow article. Also, the parison may comprise two or more concentric tubular members, some of which comprise a non-foamable plastic material to form a nonporous skin which is laminated to the foamed layer.
Inventors
- 👤 Gregory W Doll
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 02:46
CPC Classifications
B; B29; B29C; B29C44/00; B29C44/02; B29C44/12; B29C44/14; B29C44/146; B29C44/20; B29C44/22; B29C48/00; B29C48/03; B29C48/09; B29C48/16; B29C48/18; B29C48/21; B29C48/25; B29C48/30; B29C48/32; B29C48/335; B29C48/337; B29C48/36; B29C48/375; B29C48/388; B29C49/00; B29C49/02; B29C49/04; B29C49/22; B29K; B29K2105/00; B29K2105/04; B29K2105/043; Y; Y10; Y10S; Y10S264/00; Y10S264/01
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
61 words
A METHOD FOR MOLDING PLASTIC ARTICLES COMPRISING THE STEPS OF EXTRUDING A HOT FOAMABLE PLASTIC MATERIAL THROUGH AN ANNULAR ORIFICE TO FORM A TUBULAR PARISON WHILE MAINTAINING THE PLASTIC MATERIAL UNDER SUFFICIENT POSITIVE PRESSURE TO PREVENT THE FOAMING THEREOF, ENCLOSING THE PARISON WITHIN A MOLD WHILE CONTINUING TO MAINTAIN THE PLASTIC MATERIAL UNDER SUFFICIENT POSITIVE PRESSURE TO PREVENT THE FOAMING THEREOF,
Claim 2
Independent Claim
61 words
A METHOD FOR MOLDING PLASTIC ARTICLES COMPRISING THE STEPS OF EXTRUDING A HOT FOAMABLE PLASTIC MATERIAL THROUGH AN ANNULAR ORIFICE TO FORM A TUBULAR PARISON WHILE MAINTAINING THE PLASTIC MATERIAL UNDER SUFFICIENT POSITIVE PRESSURE TO PREVENT THE FOAMING THEREOF, ENCLOSING THE PARISON WITHIN A MOLD WHILE CONTINUING TO MAINTAIN THE PLASTIC MATERIAL UNDER SUFFICIENT POSITIVE PRESSURE TO PREVENT THE FOAMING THEREOF,
Claim 3
Dependent Claim
23 words
The method as defined in claim 1 wherein the step of releasing the pressure is accomplished while the plastic remains in the mold.
Claim 4
Dependent Claim
83 words
The method as defined in claim 2 comprising the further step of extruding a hot non-foamable plastic material concurrently with the extruding of the foamable plastic material and through a second annular orifice positioned concentric with and immediately adjacent to the annular orifice through which the foamable material is extruded, such that the parison comprises a first tubular member of foamable plastic material and a second tubular member of non-foamable plastic material positioned concentric with and immediately adjacent to the first tubular member.
Claim 5
Dependent Claim
45 words
The method as defined in claim 3 wherein the step of extruding a hot non-foamable plastic material includes positioning the same outside of the foamable plastic material such that the non-foamable tubular member of the parison is positioned outside of the foamable tubular member thereof.
Claim 6
Dependent Claim
43 words
The method as defined in claim 3 wherein the step of extruding a hot non-foamable plastic material includes positioning the same inside the foamable plastic material such that the non-foamable tubular member of the parison is positioned inside the foamable tubular member thereof.
Claim 7
Dependent Claim
54 words
The method as defined in claim 1 wherein the step of extruding the hot foamable material includes coordinating the amount extruded with the size of the mold such that the extruded foamable plastic material expands to fill the interior of the mold upon the pressure being released to thereby form a solid plastic article.
Claim 8
Dependent Claim
58 words
The method as defined in claim 1 wherein the step of extruding the hot foamable material includes coordinating the amount extruded with the size of the mold such that the extruded foamable plastic material expands to fill only a portion of the interior of the mold upon the pressure being released to thereby form a hollow plastic article.
Claim 9
Dependent Claim
55 words
The method as defined in claim 1 wherein the step of enclosing the parison in a mold includes maintaining the walls of the mold at a relatively low temperature such that the foamable plastic material is solidified upon contact with the walls to form a substantially non-porous skin about the periphery of the molded article.
Claim 10
Independent Claim
188 words
A method of molding layered plastic articles comprising the steps of extruding a hot foamable plastic material through a first annular orifice, while extruding a hot non-foamable plastic material through a second annular orifice positioned concentric with and immediately adjacent to the first annular orifice such that the extruded foamable plastic material and extruded non-foamable plastic material form a parison comprising a pair of concentric tubular members, while maintaining the parison under sufficient positive pressure to prevent the foaming of the extruded foamable plastic material, enclosing the parison within a mold while continuing to maintain the parison under sufficient positive pressure to prevent the foaming of the extruded foamable plastic material, blow molding the parison against the walls of the enclosing mold to form the same into a desired configuration comprising contiguous layers of the foamable plastic material and the non-foamable plastic material and while continuing to maintain the parison under sufficient positive pressure to prevent the foaming of the foamable plastic material, then releasing the positive pressure to cause the foamable plastic material to foam, and opening the mold to permit removal of the molded plastic article.
Claim 11
Independent Claim
188 words
A method of molding layered plastic articles comprising the steps of extruding a hot foamable plastic material through a first annular orifice, while extruding a hot non-foamable plastic material through a second annular orifice positioned concentric with and immediately adjacent to the first annular orifice such that the extruded foamable plastic material and extruded non-foamable plastic material form a parison comprising a pair of concentric tubular members, while maintaining the parison under sufficient positive pressure to prevent the foaming of the extruded foamable plastic material, enclosing the parison within a mold while continuing to maintain the parison under sufficient positive pressure to prevent the foaming of the extruded foamable plastic material, blow molding the parison against the walls of the enclosing mold to form the same into a desired configuration comprising contiguous layers of the foamable plastic material and the non-foamable plastic material and while continuing to maintain the parison under sufficient positive pressure to prevent the foaming of the foamable plastic material, then releasing the positive pressure to cause the foamable plastic material to foam, and opening the mold to permit removal of the molded plastic article.
Claim 12
Dependent Claim
33 words
The method as defined in claim 9 wherein the hot foamable and non-foamable plastic materials are adhesively compatible such that the contiguous layers formed during the blow molding operation are laminarly bonded together.
Claim 13
Dependent Claim
23 words
The method as defined in claim 9 wherein the step of blow mOlding the parison includes directing pressurized air into the interior thereof.
Claim 14
Dependent Claim
38 words
The method as defined in claim 9 wherein the step of extruding a hot non-foamable plastic material includes positioning the same outside the foamable plastic material such that the non-foamable plastic material contacts the walls of the mold.
Claim 15
Dependent Claim
82 words
The method as defined in claim 12 comprising the further step of extruding a second non-foamable plastic material concurrently with the extrusion of the other non-foamable plastic material and the foamable plastic material and through a third annular orifice positioned concentric with and immediately adjacent to and inside the first annular orifice such that the parison comprises three concentric tubular members and with the foamable plastic material comprising the intermediate member, and three contiguous layers are formed during the blow molding operation.
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) | 1978-08-25 | 1979-02-24 | 1979-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-25 | 1983-02-24 | 1983-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-25 | 1987-02-24 | 1987-08-26 | $7700.00 | Window Closed / Lapsed |