US3269714A

US3269714A - Continuous heat treating apparatus

Info

Publication number: US3269714A
Application number: US345435A
Authority: US
Inventors: Robert T Mckie
Original assignee: United States Steel Corp
Current assignee: United States Steel Corp
Priority date: 1964-02-17
Filing date: 1964-02-17
Publication date: 1966-08-30
Anticipated expiration: 1983-08-30

Description

Aug. 30, E966 R. T. M KIE 3,269,714

CONTINUOUS HEAT TREATING APPARATUS Filed Feb. 17, 1964 2 4 6 I I; 1 HEA TING HOLD/N6 CO0L l/VG i O'C DC DC OFF! OFSOFOFfiS I I I I I l I II I I I I I 'I l S I I I I I I \I t I l I x I I I l I I I I I I. I I

| I I I I t I I I I I I d Oil 0.0 O. GCO :LQUOOOO 00 M I i E w L M "RSI M1 I I n. A I a \8 f /2 205 I6 To I 22 Line Drive Conlra/ LINE DRIVE CONTROL l we lNl/E/VTOR ROBE/PT I McK/E A f/arn ey United States Patent CONTINUOUS HEAT TREATING APPARATUS Robert T. McKie, Bessemer, Mich, assignor to United States Steel Corporation, a corporation of Delaware Filed Feb. 17, 1964, Ser. No. 345,435 Claims. (Cl. 263-3) This invention relates to apparatus for continuously heat treating a moving elongated object such as steel strip. Apparatus of this type is shown in Perm Patent No. 2,292,511, dated August 11, 1942 and Lorig Patent No. 2,706,625, dated April 19, 1955. The strip moves continuously through a heating zone into a cooling zone which is provided with a protective atmosphere to prevent oxidation of the steel. This atmosphere is at a positive pressure so as to prevent air leakage into the furnace. When the strip stops moving for any reason the temperature in the cooling zone drops rapidly and hence the pressure of the gas also drops which can result in a negative pressure in the furnace. When this occurs air will leak into the furnace and oxidize the material being treated. As a result, the strip is not suitable for its intended purpose. Also because of contamination of the atmosphere by the air it is necessary to purge the furnace and recharge it with protective atmosphere before starting up the line. This is expensive and time consuming. In an attempt to solve this problem it has been suggested that the pressure of the protective atmosphere be increased. While this may prevent collapse of the atmosphere when the line is stopped for a short time it does not insure that the atmosphere will always remain at a positive pressure. In addition there is more tendency for the protective atmosphere to leak from the cooling chamber and it is necessary to use a substantially greater amount of the expensive atmosphere gas.

It is therefore an object of my invention to provide apparatus which will eliminate or greatly reduce the above described disadvantages.

This and other objects will be more apparent after referring to the following specification and attached drawings, in which:

The single figure is a schematic view of a continuous strip annealing furnace and the control of my invention.

Referring more particularly to the drawings, reference numeral 2 indicates the heating zone of a continuous strip annealing furnace through which the strip S passes into a holding zone 4 and hence into a cooling chamber 6. Protective atmosphere is introduced into the cooling chamber through a manifold 8. The protective atmosphere may be any of those commonly used. Bridle rolls at the entry end of the heating zone 2 are driven by a motor 12 and bridle rolls 14 at the exit end of the cooling chamber 6 are driven by a motor 16. A line drive control 18 is provided for controlling the movement of the strip through the line and includes an emergency stop. Additional drive motors may be provided and also controlled by the control 18. Strip accumulators are provided before and after the

bridles

10 and 14 and other standard equipment is provided. The parts so far described are conventional.

According to my invention I provide contacts 180 and 18C1 which are connected to be operated by the emergency stop of the control 18. The contact 18C is closed when the line is stopped and open when the line is running. The contact 18C1 is open when the line is stopped and closed when the line is running. A solenoid operated valve 20 is inserted in conduit 22 leading from a high pressure source of protective atmosphere, not shown, to the manifold 8. The power for operating solenoid 20S is provided from a 110 volt alternating current source L1, L2. A timer 24 is connected in series with contact 18C and is provided with a normally closed con- 3,269,714 Patented August 30, 1966 tact 24C. The timer 24 may be of any conventional type that will open its contact 24C after it has been energized for a predetermined time. Contact 18C1 is connected in series with push button switches 26 and 28 and relay coil 30 which has normally open contacts 30C and 30C1. Contacts 24C, 30C1 and solenoid 20S are connected in parallel with timer 24. Contact 30C is connected in parallel with contact 18C1 and switch 26.

In operation, the strip S will pass continuously through the heating zone 2, holding zone 4 and cooling chamber 6 with the valve 20 being closed, but with a protective atmosphere at a low pressure in the cooling chamber 6. While the line is running switch 26 is closed. This will energize coil 30 through switch 28 and closed contact 18C1. Energization of coil 30 closes its contacts 30C and 3001. Closing of contact 30C seals in coil 30 and push button switch 26 can be opened. Since contact 18C is open, closing of contact 30C1 will have no effect. When the line stops, contact 18C will close and contact 18C1 will open. Closing of contact 18C starts timer 24 in operation and also energizes solenoid 208 through contacts 24C and 30C1. Thus valve 20 will open immediately upon the signal for stoppage of the line and permits sufficient atmosphere to pass into the cooling chamber 6 to maintain it at a positive pressure. After a preset time the timer 24 will cause its contact 240 to open, thus deenergizing solenoid 20S and closing valve 20. The solenoid 208 may be deenergized at any time while the timer 24 is operating by opening switch 28. After the line is started up again switch 26 is again closed to place the control on automatic.

While one embodiment of my invention has been shown and described it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. Apparatus for continuously heat treating a moving elongated object which comprises a heating zone for said strip, a cooling chamber for said strip, means including a conduit for delivering a protective atmosphere to said cooling chamber, a normally closed valve in said conduit for controlling flow of protective atmosphere to said cooling chamber, means for moving said object successively through said heating zone and said cooling chamber, and means for automatically opening said valve when movement of said object through said cooling chamber begins to stop to admit protective atmosphere.

2. Apparatus for continuously heat treating a moving elongated object which comprises a heating zone, a cooling chamber, means including a conduit for delivering a protective atmosphere to said cooling chamber, a normally closed valve in said conduit for controlling flow of protective atmosphere to said cooling chamber, means for moving said object successively through said heating zone and said cooling chamber, a solenoid for operating said valve, a circuit including said solenoid, a timer, said timer having a contact in series with said solenoid, and means operable when said object begins to stop moving through said cooling chamber to complete said circuit whereby said solenoid will open said valve for a predetermined time, said timer contact opening after a predetermined time interval to cause said valve to close.

3. Apparatus for continuously heat treating a moving elongated object which comprises a heating zone for said strip, a cooling chamber for said strip, means including a conduit for delivering a protective atmosphere to said cooling chamber, a normally closed valve in said conduit for controlling flow of protective atmosphere to said cooling chamber, means for moving said object successively through said heating zone and said cooling chamber, control means for stopping and starting movement of said object moving means, and means operable by said control means when movement of said object begins to stop and open said valve to admit protective atmosphere.

4. Apparatus for continuously heat treating a moving elongated object which comprises a heating zone, a cooling chamber, means including a conduit for delivering a protective atmosphere to said cooling chamber, a normally closed valve in said conduit for controlling flow of protective atmosphere to said cooling chamber, means for moving said object successively through said heating zone and said cooling chamber, control means for stopping and starting movement of said object moving means, a solenoid for operating said valve, a circuit including said solenoid, a timer, and means operable by said control means for actuating said timer and completing said circuit when said object begins to stop moving through said cooling chamber whereby said solenoid will open said valve for a predetermined time.

5. Apparatus for continuously heat treating a moving elongated object which comprises a heating zone, a cooling chamber, means including a conduit for delivering a protective atmosphere to said cooling chamber, a normally closed valve in said conduit for controlling flow of protective atmosphere to said cooling chamber, means for moving said object successively through said heating zone and said cooling chamber, control means for stopping and starting movement of said object, a solenoid for operating said valve, a circuit including said solenoid, a timer having a contact in series with said solenoid, and means operable by said control means for actuating said timer and completing said circuit when said object begins to stop moving through said cooling chamber whereby said solenoid Will open said valve for a predetermined time, said timer opening its contact after a predetermined time interval to deenergize said circuit and cause said valve to close.

References Cited by the Examiner UNITED STATES PATENTS 2,009,856 7/1935 Otis et al. 263-3 2,534,973 12/1950 Ipsen et al. 2663 2,838,296 6/1958 White 263-3 JOHN J, CAMBY, Acting Primary Examiner.