Patent US3778221A successfully refreshed from Google Patents.
US3778221A
Expired / Lapsed
US
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Annealing furnace and method for its operation
Assignee: Allegheny Ludlum Corp
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Filing: 1971-09-17
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Granted: 1973-12-11
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Expires: 1991-09-17
Abstract
Abstract A furnace, and method of furnace operation, for annealing whole coils of steel, particularly silicon steel. The furnace includes a welded gas-tight shell lined with varying thicknesses of refractory material defining a plurality of independently controllable heating and cooling zones and in which a vacuum is maintained at the entry section and a hydrogen atmosphere in all other sections. The furnace additionally includes vacuum-purged vestibules at both ends to accommodate the entrance and exit of coils from the interior atmosphere of the furnace.
Inventors
- 👤 W Bloom
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 13:46
CPC Classifications
C; C21; C21D; C21D1/00; C21D1/74
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
155 words
In the method for heat treating strip material in coil form by the steps of positioning a coil in vestibule means aT the entrance end of a furnace having successive heating and cooling zones between entrance and exit ends, sealing said vestibule means and purging the same of gaseous contaminants, thereafter transferring the coil from the vestibule means to the furnace and moving said coil from the entrance end of the furnace through successive heating and cooling zones of the furnace while circulating through said furnace a non-oxidizing gas, and finally removing the coil from the exit end of said furnace; the improvement in said method which comprises: 1. initially evacuating said vestibule means to purge it of gaseous contaminants, 2. then filling said vestibule means with a non-oxidizing gas, and 3. again evacuating said vestibule means to purge it of said gas before the coil is transferred from said vestibule means to said furnace.
Claim 2
Dependent Claim
155 words
In the method for heat treating strip material in coil form by the steps of positioning a coil in vestibule means aT the entrance end of a furnace having successive heating and cooling zones between entrance and exit ends, sealing said vestibule means and purging the same of gaseous contaminants, thereafter transferring the coil from the vestibule means to the furnace and moving said coil from the entrance end of the furnace through successive heating and cooling zones of the furnace while circulating through said furnace a non-oxidizing gas, and finally removing the coil from the exit end of said furnace; the improvement in said method which comprises: 1. initially evacuating said vestibule means to purge it of gaseous contaminants, 2. then filling said vestibule means with a non-oxidizing gas, and 3. again evacuating said vestibule means to purge it of said gas before the coil is transferred from said vestibule means to said furnace.
Claim 3
Dependent Claim
10 words
then filling said vestibule means with a non-oxidizing gas, and
Claim 4
Dependent Claim
10 words
then filling said vestibule means with a non-oxidizing gas, and
Claim 5
Dependent Claim
22 words
The method of claim 1 wherein said non-oxidizing gas and the non-oxidizing gas with which said vestibule means is filled comprises hydrogen.
Claim 6
Dependent Claim
23 words
again evacuating said vestibule means to purge it of said gas before the coil is transferred from said vestibule means to said furnace.
Claim 7
Dependent Claim
23 words
again evacuating said vestibule means to purge it of said gas before the coil is transferred from said vestibule means to said furnace.
Claim 8
Dependent Claim
47 words
The method of claim 1 including the step of transferring the coil from the exit end of said furnace to second vestibule means and purging the last-mentioned vestibule means of said non-oxidizing gas prior to discharge of the coil from the last-mentioned vestibule means into the atmosphere.
Claim 9
Dependent Claim
48 words
The method of claim 1 including the step of initially heating said coil within said furnace while evacuating the space around it before said coil is subjected to said non-oxidizing gas within the furnace, whereby water of hydration will be removed from the surfaces of said strip material.
Claim 10
Dependent Claim
76 words
The method of claim 4 including the step of closing door means at both ends of said vestibule means during evacuation of the vestibule means, opening door means between the vestibule means and an initial furnace section while closing door means at the other end of said initial furnace section and moving a coil from said vestibule means to said initial furnace section, and then closing the first-mentioned door means while evacuating said initial furnace section.
Claim 11
Dependent Claim
69 words
In the method for heat treating strip material in coil form by the steps of moving said coil through successive heating and cooling zones of a furnace while circulating through said furnace a non-oxidizing gas, the improvement which comprises: initially heating said coil in an evacuated chamber prior to its passage through said furnace containing a non-oxidizing atmosphere to remove from the surfaces of said coil any water vapor.
Claim 12
Dependent Claim
69 words
In the method for heat treating strip material in coil form by the steps of moving said coil through successive heating and cooling zones of a furnace while circulating through said furnace a non-oxidizing gas, the improvement which comprises: initially heating said coil in an evacuated chamber prior to its passage through said furnace containing a non-oxidizing atmosphere to remove from the surfaces of said coil any water vapor.
Claim 13
Dependent Claim
40 words
The method of claim 6 which includes placing said coil in a vestibule chamber at the entry end of said evacuated chamber, then creating a sub-atmospheric pressure in said vestibule chamber, and then moving said coil into said evacuated chamber.
Claim 14
Dependent Claim
70 words
The method of claim 6 in which said evacuated chamber includes a heating section, a transfer section at the exit end of the heating section and a sealing door at each end of the transfer section, said initial heating being done in said heating section, said method including moving said coil into said transfer section while the exit door is closed, and then introducing non-oxidizing gas into said transfer section.
Claim 15
Dependent Claim
115 words
Apparatus for heat treating strip material in coil form comprising a furnace structure, means for dividing said furnace structure into a plurality of independently controllable heating zones and a plurality of independently controllable cooling zones, means for supporting and advancing coils through said furnace structure, door means sealing the heating zone at the entrance end of said furnace structure from the rest of the furnace structure to provide a sealable chamber, means for generating heat within said sealable chamber, means for creating a sub-atmospheric pressure in said sealable chamber while a coil of heated strip material is present therein, and means for circulating a non-oxidizing gas through the rest of said heating and cooling zones.
Claim 16
Dependent Claim
115 words
Apparatus for heat treating strip material in coil form comprising a furnace structure, means for dividing said furnace structure into a plurality of independently controllable heating zones and a plurality of independently controllable cooling zones, means for supporting and advancing coils through said furnace structure, door means sealing the heating zone at the entrance end of said furnace structure from the rest of the furnace structure to provide a sealable chamber, means for generating heat within said sealable chamber, means for creating a sub-atmospheric pressure in said sealable chamber while a coil of heated strip material is present therein, and means for circulating a non-oxidizing gas through the rest of said heating and cooling zones.
Claim 17
Dependent Claim
40 words
Apparatus according to claim 9 in which said sealable chamber includes a heatIng section, a transfer section at the exit end of the heating section, and said door means including a sealing door at each end of the heating section.
Claim 18
Dependent Claim
35 words
Apparatus according to claim 10 including means for creating sub-atmospheric pressure in said transfer section while said doors are closed and means for filling said transfer section with non-oxidizing gas while said doors are closed.
Claim 19
Dependent Claim
77 words
Apparatus according to claim 10 including a sealable vestibule for receiving coils of strip material to be heat treated in said furnace structure, door means between said vestibule and said heating section, means providing a sub-atmospheric pressure in said vestibule after a coil to be heat treated in placed therein and while said vestibule door means is closed, and means for thereafter introducing said non-oxidizing gas into said vestibule while said vestibule door means is still closed.
Claim 20
Dependent Claim
16 words
The apparatus of claim 10 including back-up purging means for purging said vestibule with nitrogen gas.
Claim 21
Dependent Claim
56 words
The apparatus of claim 10 including a second sealable vestibule at the exit end of said furnace structure, door means between said second vestibule and the interior of the furnace structure, door means between said second vestibule and the atmosphere, means for evacuating said second vestibule, and back-up means for purging said second vestibule with nitrogen.
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) | 1976-12-10 | 1977-06-11 | 1977-12-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-10 | 1981-06-11 | 1981-12-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-10 | 1985-06-11 | 1985-12-11 | $7700.00 | Window Closed / Lapsed |