US4396816A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for processing polyethylene terephthalate preforms
Assignee: Graham Packaging Pet Technologies Inc
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Filing: 1981-11-02
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Granted: 1983-08-02
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Expires: 2001-11-02
Abstract
Abstract This relates to the heating of polyethylene terephthalate by way of RF energy. It has been found that if polyethylene terephthalate articles are passed through a radio frequency energy field, the molecules thereof will become excited and rapid heating will result. This heating is particularly useful in the heating of preforms prior to the blow molding thereof and by varying the configuration and relationship of electrodes, controlled heating of the preforms may be effected with it being possible to have a controlled temperature differential along the length of the preform or other article so heated.
Inventors
- 👤 Suppayan M. Krishnakumar
- 👤 John F. E. Pocock
- 👤 Gautam K. Mahajan
- 👤 John F. Trembly
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 19:31
CPC Classifications
B; B29; B29C; B29C35/00; B29C35/02; B29C35/12; B29C49/00; B29C49/42; B29C49/64; B29C49/6409; B29C49/6418; B29C49/6436; B29C49/6445; B29C49/68; B29C49/682; H; H05; H05B; H05B6/00; H05B6/46; H05B6/60; B29C35/08; B29C35/0805; B29C2035/0822; B29C2035/0861; B29C49/78; B29C49/786; B29C2049/7861; B29C2949/00; B29C2949/07; B29C2949/0715; B29C49/02; B29C49/06; B29K; B29K2067/00; Y; Y10; Y10S; Y10S264/00; Y10S264/46
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
127 words
Apparatus for heating a molded thermoplastic hollow preform having a closed bottom, said apparatus comprising an electrical supply of the radio frequency type and having a voltage not in excess of the dielectric breakdown of the thermoplastic material, a pair of electrodes disposed in side-by-side transversely spaced relation and defining a preform path therebetween, conveyor means for conveying preforms along said path in spaced parallel relation to one another and in spaced relation to said electrodes, while rotating the preforms about their axes, means connecting said radio frequency electrical supply to said electrodes for forming therebetween along said path a radio frequency energy field, said electrodes having a relationship other than being identical and in parallel aligned relation for effecting controlled heating of selected portions of preforms.
Claim 2
Dependent Claim
127 words
Apparatus for heating a molded thermoplastic hollow preform having a closed bottom, said apparatus comprising an electrical supply of the radio frequency type and having a voltage not in excess of the dielectric breakdown of the thermoplastic material, a pair of electrodes disposed in side-by-side transversely spaced relation and defining a preform path therebetween, conveyor means for conveying preforms along said path in spaced parallel relation to one another and in spaced relation to said electrodes, while rotating the preforms about their axes, means connecting said radio frequency electrical supply to said electrodes for forming therebetween along said path a radio frequency energy field, said electrodes having a relationship other than being identical and in parallel aligned relation for effecting controlled heating of selected portions of preforms.
Claim 3
Dependent Claim
57 words
Apparatus according to claim 1 wherein said conveyor means are particularly adapted to convey preforms with the closed ends thereof being of a preselected orientation along said path, and said electrode relationship including said electrodes being offset in a height direction adjacent the path of the preform closed ends to limit the heating of the closed ends.
Claim 4
Dependent Claim
61 words
Apparatus according to claim 1 wherein said electrode relationship includes at least one of said electrodes being of a non-planar shape to selectively vary the transverse spacing between said electrodes and a preform positioned between said electrodes in a height direction thereby varying the intensity of said field in selected areas thereof and thus temperature profiling preforms in a length direction.
Claim 5
Dependent Claim
19 words
Apparatus according to claim 1 wherein said radio frequency field is within the range of 13 to 98 megahertz.
Claim 6
Dependent Claim
29 words
Apparatus according to claim 1 wherein conveyor means moves at a rate to maintain a preform between said electrodes for a period of time of 29 seconds or less.
Claim 7
Dependent Claim
27 words
Apparatus according to claim 1 wherein conveyor means moves at a rate to maintain a preform between said electrodes for a period of time of 5-25 seconds.
Claim 8
Dependent Claim
22 words
Apparatus according to claim 1 wherein said conveyor means includes spaced collets each having means for releasable interlocking engagement with a preform.
Claim 9
Dependent Claim
19 words
Apparatus according to claim 7 wherein one of said electrodes is grounded and each of said collets is grounded.
Claim 10
Dependent Claim
160 words
Apparatus for heating a molded thermoplastic hollow preform having a closed bottom, said apparatus comprising an electrical supply of the radio frequency type and having a voltage not in excess of the dielectric breakdown of the thermoplastic material, a pair of electrodes disposed in side-by-side transversely spaced relation and defining a preform path therebetween, conveyor means for conveying preforms along said path in spaced parallel relation to one another and in spaced relation to said electrodes while rotating the preforms about their axes, means connecting said radio frequency electrical supply to said electrodes for forming therebetween along said path a radio frequency energy field, said radio frequency electrical supply being of the variable power type, detector means for detecting the individual temperature of heated preforms, and control means for said power of said radio frequency electrical supply coupled to said detector means for varying said power in accordance with detected preform temperature to provide uniform heating of adjacent moving preforms.
Claim 11
Dependent Claim
160 words
Apparatus for heating a molded thermoplastic hollow preform having a closed bottom, said apparatus comprising an electrical supply of the radio frequency type and having a voltage not in excess of the dielectric breakdown of the thermoplastic material, a pair of electrodes disposed in side-by-side transversely spaced relation and defining a preform path therebetween, conveyor means for conveying preforms along said path in spaced parallel relation to one another and in spaced relation to said electrodes while rotating the preforms about their axes, means connecting said radio frequency electrical supply to said electrodes for forming therebetween along said path a radio frequency energy field, said radio frequency electrical supply being of the variable power type, detector means for detecting the individual temperature of heated preforms, and control means for said power of said radio frequency electrical supply coupled to said detector means for varying said power in accordance with detected preform temperature to provide uniform heating of adjacent moving preforms.
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) | 1986-08-01 | 1987-01-31 | 1987-08-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-08-01 | 1991-01-31 | 1991-08-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-08-01 | 1995-01-31 | 1995-08-02 | $7700.00 | Window Closed / Lapsed |