US3720546A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for preventing destruction of strip metal in annealing furnace connected with direct heating furnace
Assignee: Nippon Steel Corp
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Filing: 1970-04-13
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Granted: 1973-03-13
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Expires: 1990-04-13
Abstract
Abstract Method for preventing destruction of a strip of metal moving in treatment line containing a continuous annealing furnace connected with a direct-heating furnace due to over-oxidation during longer than normal residence in the direct heating furnace, that is, before re-starting from an exigent stoppage of the line, which method is so carried out that at the same time with such stoppage, the opening for air outside of said direct heating furnace is closed, and combustion continues at limited operation rate of the burner, hardly reducing the temperature inside the furnace but maintaining the atmosphere inside the furnace non-oxidant.
Inventors
- 👤 S Ayusawa
- 👤 K Iwasaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 00:16
CPC Classifications
C; C21; C21D; C21D9/00; C21D9/52; C21D9/54; C21D9/56; C21D9/561; C23; C23C; C23C2/00; C23C2/003; C23C2/0034; C23C2/00342; C23C2/00344; C23C2/0035; C23C2/0038; C23C2/004; C23C2/02; C23C2/022; C23C2/0222; C23C2/0224
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
211 words
A method for preventing the breakage of steel strip which has stopped during treatment in which it is being passed through a continuous annealing furnace which is comprised of a direct heating furnace portion having a burner therein followed by a reduction furnace portion, the burner being operated during normal annealing at a normal burning rate for maintaining the temperature at a normal annealing temperature, said method comprising, at the time the strip is stopped, closing the portions of the annealing furnace open to the air while continuing the operation of the burner in the direct heating furnace portion at substantially complete combustion conditions and at a burning rate which is no more than one-fifth the normal burning rate and is such as to maintain the temperature of the furnace so that it does not drop below said normal annealing temperature, and maintaining the pressure inside the annealing furnace positive relative to atmospheric pressure and preventing air from coming into the annealing furnace from outside the annealing furnace to maintain the atmosphere inside the annealing furnace non-oxidizing so that the steel strip is prevented from breaking even though it must stay for a long time within the furnace at the annealing temperature or above due to the stoppage of the strip.
Claim 2
Independent Claim
211 words
A method for preventing the breakage of steel strip which has stopped during treatment in which it is being passed through a continuous annealing furnace which is comprised of a direct heating furnace portion having a burner therein followed by a reduction furnace portion, the burner being operated during normal annealing at a normal burning rate for maintaining the temperature at a normal annealing temperature, said method comprising, at the time the strip is stopped, closing the portions of the annealing furnace open to the air while continuing the operation of the burner in the direct heating furnace portion at substantially complete combustion conditions and at a burning rate which is no more than one-fifth the normal burning rate and is such as to maintain the temperature of the furnace so that it does not drop below said normal annealing temperature, and maintaining the pressure inside the annealing furnace positive relative to atmospheric pressure and preventing air from coming into the annealing furnace from outside the annealing furnace to maintain the atmosphere inside the annealing furnace non-oxidizing so that the steel strip is prevented from breaking even though it must stay for a long time within the furnace at the annealing temperature or above due to the stoppage of the strip.
Claim 3
Dependent Claim
27 words
The method as claimed in claim 1, wherein the rate of burning of said burner is reduced to one-fifth to one-tenth of the normal rate of burning.
Claim 4
Dependent Claim
28 words
The method as claimed in claim 1, wherein the reduced burning rate of said burner is sufficient to make the pressure inside the furnace several mm H2O positive.
Claim 5
Dependent Claim
38 words
The method as claimed in claim 1, wherein said furnace has chimney means with damper means therein, and said step of closing of the portions of the annealing furnace open to the air comprises closing the damper means.
Claim 6
Dependent Claim
42 words
The method as claimed in claim 4 wherein said furnace further has seal rolls through which the strip enters the furnace, and said step of closing the portions of the annealing furnace open to the air further comprises closing said seal rolls.
References Cited (Backward Citations)
US3496033A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-12 | 1976-09-11 | 1977-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-12 | 1980-09-11 | 1981-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-12 | 1984-09-11 | 1985-03-13 | $7700.00 | Window Closed / Lapsed |