US4333905A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for blowmolding a container
Assignee: BOMATIC Inc A ST
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Filing: 1980-10-15
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Granted: 1982-06-08
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Expires: 2000-10-15
Abstract
Abstract A method for blow molding of containers with a thickened bead at the bottom end thereof by the steps of extruding a tubular parison, closing the mold thereabout, preblowing the parison within a mold cavity under low pressure so as to partially inflate the parison to a major extent, raising the bottom wall of the mold cavity so as to contact the partially inflated parison in a manner forming a thickened bead between bottom and surrounding adjacent mold cavity wall parts, and thereafter finish-blowing the parison within the mold cavity with a blow medium under high pressure so as to inflate the parison to the intended finished size before opening of the mold for removal of the container.
Inventors
- 👤 Borge Hestehave
- 👤 Kjeld Hestehave
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 02:46
CPC Classifications
B; B29; B29C; B29C49/00; B29C49/42; B29C49/48; B29C49/54; B29C49/541; B29C49/18; B29C49/4802
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
177 words
A method for the blow molding of a plastic container with a thickened bead at the bottom thereof comprising the steps of: (a) extruding a tubular parison between parts of a blow mold; (b) closing said mold parts about said parison so as to define a molding cavity of a greater size than the intended finished size of said container; (c) preblowing said parison within said molding cavity with a blowing medium under low pressure so as to partially inflate said parison to approximately 95% of said finizhed size has been inserted; (d) raising a molding cavity bottom wall part of said blow mold so as to compact 2 double-wall thickness of said partially inflated parison in a manner forming a thickened bead in a circumferential bead forming recess between said bottom wall part and adjacent surrounding molding cavity parts; (e) finish-blowing said parison within said molding cavity with a blowing medium under high pressure so as to inflate said parison to said intended finished size; and (f) opening said mold parts for removal of said container.
Claim 2
Independent Claim
177 words
A method for the blow molding of a plastic container with a thickened bead at the bottom thereof comprising the steps of: (a) extruding a tubular parison between parts of a blow mold; (b) closing said mold parts about said parison so as to define a molding cavity of a greater size than the intended finished size of said container; (c) preblowing said parison within said molding cavity with a blowing medium under low pressure so as to partially inflate said parison to approximately 95% of said finizhed size has been inserted; (d) raising a molding cavity bottom wall part of said blow mold so as to compact 2 double-wall thickness of said partially inflated parison in a manner forming a thickened bead in a circumferential bead forming recess between said bottom wall part and adjacent surrounding molding cavity parts; (e) finish-blowing said parison within said molding cavity with a blowing medium under high pressure so as to inflate said parison to said intended finished size; and (f) opening said mold parts for removal of said container.
Claim 3
Dependent Claim
29 words
A molding method according to claim 1, wherein said closing step is performed so as to pinch closed said parison at the top and bottom of said mold cavity.
Claim 4
Dependent Claim
27 words
A molding method according to claim 1, wherein said preblowing step is performed with said low pressure blowing medium being at a pressure of about 15-20 psi.
Claim 5
Dependent Claim
27 words
A molding method according to claim 3, wherein said finish-blowing step is performed with said high pressure blowing medium being at a pressure of about 80-100 psi.
Claim 6
Dependent Claim
25 words
A molding method according to claim 4, comprising the step of cooling said mold parts after said finish-blowing step and prior to said opening step.
Claim 7
Dependent Claim
16 words
A molding method according to claim 4, wherein said parison is formed of high density polyethylene.
Claim 8
Dependent Claim
32 words
A molding method according to claim 1 or 3 or 4, wherein said parison is brought into contact with a portion of side walls of said molding cavity during said preblowing step.
Claim 9
Dependent Claim
51 words
A molding method according to claim 1 or 3 or 4, wherein said raising step produces a bead of approximately the same thickness as the wall thickness of the extrude parison and wherein said blowing steps produce a container having a side wall thickness approximately half that of said extruded parison.
Claim 10
Dependent Claim
51 words
A method according to claim 8, wherein said extruding step is performed so as to produce a parison of an approximately 3 inch diameter and a 0.125 inch wall thickness, and wherein said blowing steps produce a container approximately 6 inches in diameter with a wall thickness of approximately 0.050-0.070 inches.
Claim 11
Dependent Claim
24 words
A method according to claim 8, wherein said preblowing is performed for approximately 0.5-1.0 seconds and said finish-blowing is performed for approximately 15-20 seconds.
Claim 12
Dependent Claim
28 words
A method according to claim 1 or 3 or 4, wherein said preblowing is performed for approximately 0.5-1.0 seconds and said finish-blowing is performed for approximately 15-20 seconds.
Claim 13
Dependent Claim
123 words
A method according to claim 1 or 3 or 4, wherein a snap-on closure for said container is formed simultaneously with said container and connected to said container at an upper rim thereof by a severable connection by expanding said parison into a formation for forming a radially-projecting lip at an upper rim of the container that is recessed into an upper part of a container side wall defining portion of the mold cavity and into a closure forming cavity portion located thereabove, said closure forming cavity portion having a surface portion that adjoins and overlies the lip-forming formation, whereby said severable connection is formed at a defined area of separation created between the closure and radially-projecting container lip at the container rim.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-06-07 | 1985-12-07 | 1986-06-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-06-07 | 1989-12-07 | 1990-06-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-06-07 | 1993-12-07 | 1994-06-08 | $7700.00 | Window Closed / Lapsed |