US4715436A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Construction of a heat transfer wall of a heat transfer pipe
Assignee: Hitachi Cable Ltd
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Filing: 1985-09-18
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Granted: 1987-12-29
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Expires: 2005-09-18
Abstract
Abstract A heat transfer tube has at least a row of projections provided on its inner surface at regular intervals along a spiral curve thereof. The row of projections are formed by plastic deformation of part of the heat transfer tube, which is effected by pressing a rolling disc having projections against the outer surface of the heat transfer tube. The projections have smooth curved surfaces. The height of the projections ranges from 0.45 mm to 0.6 mm, their pitch along the spiral curve ranges from 3.5 mm to 5 mm, and their pitch in the axial direction ranges from 5 mm to 9 mm.
Inventors
- 👤 Kenji Takahashi
- 👤 Heikichi Kuwahara
- 👤 Takehiko Yanagida
- 👤 Wataru Nakayama
- 👤 Kiyoshi Oizumi
- 👤 Shigeo Sugimoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 06:07
CPC Classifications
F; F28; F28F; F28F13/00; F28F13/18; F28F13/185; B; B21; B21C; B21C37/00; B21C37/06; B21C37/15; B21C37/20; B21D; B21D17/00; B21D17/04; F28F1/00; F28F1/10; F28F1/42; F28F1/44
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
160 words
A heat transfer tube comprising: at least one row of projections provided on an inner surface of said heat transfer tube at regular intervals along a spiral curve thereof, said projections having smooth curved surfaces formed by plastic deformation of a part of said heat transfer tube which is effected by pressing a rolling disc provided with tooth means against an outer surface of said heat transfer tube, said projections having a height ranging from 0.45 mm to 0.6 mm, a pitch along the spiral curve ranging from 3.5 mm to 5 mm, and a pitch in an axial direction ranging from 5 mm to 9 mm; a plurality of parallel minute grooves formed at a minute pitch on the outer surface thereof; a plurality of minute fins provided between said grooves; and notches formed on said minute fins and having a depth smaller than said grooves; and wherein a forward end of each of said fins is sharply pointed.
Claim 2
Dependent Claim
160 words
A heat transfer tube comprising: at least one row of projections provided on an inner surface of said heat transfer tube at regular intervals along a spiral curve thereof, said projections having smooth curved surfaces formed by plastic deformation of a part of said heat transfer tube which is effected by pressing a rolling disc provided with tooth means against an outer surface of said heat transfer tube, said projections having a height ranging from 0.45 mm to 0.6 mm, a pitch along the spiral curve ranging from 3.5 mm to 5 mm, and a pitch in an axial direction ranging from 5 mm to 9 mm; a plurality of parallel minute grooves formed at a minute pitch on the outer surface thereof; a plurality of minute fins provided between said grooves; and notches formed on said minute fins and having a depth smaller than said grooves; and wherein a forward end of each of said fins is sharply pointed.
References Cited (Backward Citations)
GB862458A
Cited
US3481394A
Cited
US3734140A
Cited
US3847212A
Cited
US4166498A
Cited
US4332294A
Cited
GB2037974A
Cited
US4314587A
Cited
US4330036A
Cited
US4425942A
Cited
JPS588995A
Cited
JPS58208595A
Cited
US4549606A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-12-28 | 1991-06-29 | 1991-12-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-12-28 | 1995-06-29 | 1995-12-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-12-28 | 1999-06-29 | 1999-12-29 | $7700.00 | Window Closed / Lapsed |