US2162143A - Apparatus for the annealing of metal - Google Patents

Description

June 13, 1939. w VREELAND 2,162,143

APPARATUS FOR THE ANNEALING OF METAL Filed July l, 1937 2 Sheets-Sheet 2 V\ m Y &9 a

C N L "D Gear' call rflaroa NJ) I Patented June 13, 1939 PATENT OFFICE APPARATUS FOR THE ANNEALING OF METAL George W. Vreeland, Maplewood, N. J., assignor to H. A. Brassert & Company, Chicago, Ill., a corporation oi' [Ilinois Application July 1, 1937, Serial No. 151375 1 Claim.

This invention relates to a new and-improved apparatus for the annealing of metal and to such a method particularly adapted for the annealing of steel strip or w'ire in coils.

The proper annealing of metal requires its gradual heating to a predetermined temperature, its maintenance at that temperature for a given time, and its proper cooling. The tempe'aturcs, temperature gradients and times will vary with difierent metals and diifering conditions and requirements.

In general, annealing at present is carried out by three difierent methods. The usual box method is one in which an ordinary type of regenerative or recuperative iurnace which is rectangular in plan, is used and coils are placed in the boxes in a row or rows within the furnace chamber, the fuel burning on the outside of the boxes. This is inefiicient to fuel consumption and in uni- 20 formity of heating, and also requires additional apparatus tor removing and installing the boxes in the furnace.

Another method is that of the removable cover annealing furnace, where the material is placed 2 in the furnace without individual covers, and the heating is carried on in tubes placed variously in the furnace. The tubes are heated by burning gas in them or passing highly heated gas through them.

The third method is the electric furnace method where heating coils are provided around the walls of the furnace and in some cases in the center of the Iurnace. This method involves an excessively high cost of installation and high electric fuel cost, especially in comparison with plants that have available their own gaseous fuels. such as blat furnace gas, coke oven gas or a mixture of these gases.

It is an object of the present inventicn to pro- 40 vide new and improved apparatus for annealing. It is a further object to provide a furnace which is low in cost of manufacture and of maintenance.

It is also an object to provide a furnace for 45 using eificiently low grade and inexpensive fuel such as blast furnace gas. l

It is an additional object to provide an apparatus which aflords rapid and uniform heating all around the coils of metal being treated and by which, during the cooling stage, the covers for the metal are exposed to the air to accelerate cooling.

Other and further objects will appear as the description proceeds.

I have shown certain preferred embodiments of a furnace of my invention, in the accompany- ?ne drawings, in which- Figura 1 is a partly broken away plan view of a furnace, with the wall in section;

Figure 2 is a fragmentary vertical section of the furnace of Figure 1; and

Figure 3 is a view of a portion of Figure 2 but showing a modified form of construction.

Referring first to Figures 1 and 2, there is provided a circular base ll having a metal outer wall !2. This base provides a circular trench !3 which provides a combustion space for a plurality of low pressure burners ll which enter tangentially from the periphery of the base. Gaseous fuel and air are provided for the burners M through pipes |5 and I 6. It will be understood that liquid fuel may be used if desired.

At the upper edge of the base a scaling trench l'l is provided which is filled with sand for sealing purposes. located in the center of the base and the waste gas oiftake passa ze !9 is locatedsubstantially in the center of the floor IS. The passage 19 is provided with a removable cover 20 which may be used when the chamber is not receiving heating gases.

The coils of material being treated 2|, are placed on cast steel bases 22 which are supported above the floor I& by blocks 23. The edge of the steel base 22 carries a recess 24 receiving sand to seal the removable metal box 25 which covers the coils 2l to be annealed. A thermocouple 26 extends through the base 22 and is provided with an outside connection 21 so that the temperature of the material being annealed may be constantly observed. A tube 28 enters the box 25 through the base 22 for the introduction of a non-oxidizing gas with which the box is filled during the process. so as to force out air and prevent oxidation of the material being annealed.

The removable cover 2! fits onto the base I I and is provided with a metal flange 30 extending down into the sand seal recess I'I. This cover is provided with a lining of refractory material 3! and refractory roof 32. It will be noted that the inner wall of the refractory lining 3| of the cover inclines inwardly and upwardly so as to direct the hot gases from the trench |3 against and between the boxes 25.

In the form of construction shown in Figura 3, boxes 40 are provided which have central vertical flues 4l. These flues communicate with angularly inclined flues 42 in the base 13, these flues 42 extending to the central flue 44 which is similar to flue i! of the form of construction of Figures 1 and 2. The partia] cover 45 is pro- The material receiving floor IB is vided for the opening of flue 44, which cover serves to reduce the eflective area o! the flue and force some of the products o! combustion to pass down through flues "and into flue 44 through flue 42. The thermocouple 45 and pipe 48 for introdcing non-oxidizing gases, are also provided in this construction in the same manner as that of Figures 1 and 2.

In general, an installation will preferably include three platforms and a single cover. Thus one platform may be used to put in place the material to be annealed, while a second platform is enclosed by the cover and is being used to heat material, and the third supports material in the process of cooling. The burners l4 are y put in operation after the cover 29 is installed and the material is gradually brought up to"'the desired temperature, the temperatures being ob served by means of the pyrometers connected to the thermocouples 26.

In a preferred method of operation of the !urnace, where dead, soft steel is desired, a temperature of approximately 1500 F. is 'maintained in the main body of the furnace and a temperature of within five degrees Fahrenheit of 1350 F. is preferably reached within the coils !I in the boxes 25. It will be understand that during this heating operation, non-oxidizing gas is provided through pipes 28 so as to prevent oxidation of the material being annealed.

The usual cycle consists in heating up for approximately fitteen hours and then reducing the gas flow and equalizing the temperatures throughout the coils of material so as to present over or under heating of the steel. The steel may be maintained at the predetermined temperature for approximately three hours and then be permitted to cool. The cover 29 is removed during the cooling, although the boxes 25 or 40 are preferably not removed until the material has been reduced to a temperature of less than 250" F., after which oxidation is not of importance. It is preferable to install the covers 20 in aman-s the central passages IQ after the main !urnace cover is removed so as to avoid affecting the draft to the furnace being heated. Usually the three passages i! in the three 'pases of an installaticn are connected to a single stack and in addition, damper controls of the passages may i be provided.

Under usual Operating conditions it is ordinarily prei'erable to maintain a slight positive pressure throughout the chamber. If desired, waste heat may be used to preheat the air sent to the burners l4 for combustion. If blast furnace gas alone is used, it may also be desirable to preheat it to increase the efliciency of operation.

In the form of construction shown in Figure 3,

the partia] cover 45' is installed during the heating-operation so as to 'limit the passage of gases directly to the main central flue 44 and insure that the desired portion of these will go down the central fiues 4| of the boxes 40. The blocks 23 which raise the steel bottoms above the floor ll are desirable to insure uniform heating oi' the lower coils and prevent cold bottoms which occur when the bases are placed directly on the floor.

While I have shown certain preferred forms of apparatus for carrying out my invention it is to be understood that the apparatus may be modifled to meet varying conditions and requirements and I contemplate such changes as come within the spirit and scope of the appended claim.

I claim:

A platform type annealing i'urnace, comprislng a platform of substantially circular shape having burners extending inwardly at its periphery, waste gas withdrawing means adiacent the center, an intermediate, circularly extending material receiving floor. cylindrical material receiving containers on said floor, said containers having central vertical fiues, connections below said. fiues to the central waste gas withdrawing means, and a removable cover seating on said platform.

GEORGE W. VREELAND.

CERTIFICATE OF CORRECTION Patent No. 2,162,lh5.

June 1939.,

GEORGE w. VREELAND.

It ie hereby certifed that error appears in the printed specification of the above numbered patent requiring correction as followe: Page l, first column, line 19, for the word "to" read in; page 2, first column, line 51 for "present" read prevent; and that the said Letters Patent shouldbe read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 25th day of July, A. D. 1959.

(Seal) Henry Van Arsdae,

Acting Commissioner of Patents.

vided for the opening of flue 44, which cover serves to reduce the eflective area o! the flue and force some of the products o! combustion to pass down through flues "and into flue 44 through flue 42. The thermocouple 45 and pipe 48 for introdcing non-oxidizing gases, are also provided in this construction in the same manner as that of Figures 1 and 2.

In general, an installation will preferably include three platforms and a single cover. Thus one platform may be used to put in place the material to be annealed, while a second platform is enclosed by the cover and is being used to heat material, and the third supports material in the process of cooling. The burners l4 are y put in operation after the cover 29 is installed and the material is gradually brought up to"'the desired temperature, the temperatures being ob served by means of the pyrometers connected to the thermocouples 26.

In a preferred method of operation of the !urnace, where dead, soft steel is desired, a temperature of approximately 1500 F. is 'maintained in the main body of the furnace and a temperature of within five degrees Fahrenheit of 1350 F. is preferably reached within the coils !I in the boxes 25. It will be understand that during this heating operation, non-oxidizing gas is provided through pipes 28 so as to prevent oxidation of the material being annealed.

The usual cycle consists in heating up for approximately fitteen hours and then reducing the gas flow and equalizing the temperatures throughout the coils of material so as to present over or under heating of the steel. The steel may be maintained at the predetermined temperature for approximately three hours and then be permitted to cool. The cover 29 is removed during the cooling, although the boxes 25 or 40 are preferably not removed until the material has been reduced to a temperature of less than 250" F., after which oxidation is not of importance. It is preferable to install the covers 20 in aman-s the central passages IQ after the main !urnace cover is removed so as to avoid affecting the draft to the furnace being heated. Usually the three passages i! in the three 'pases of an installaticn are connected to a single stack and in addition, damper controls of the passages may i be provided.

Under usual Operating conditions it is ordinarily prei'erable to maintain a slight positive pressure throughout the chamber. If desired, waste heat may be used to preheat the air sent to the burners l4 for combustion. If blast furnace gas alone is used, it may also be desirable to preheat it to increase the efliciency of operation.

In the form of construction shown in Figure 3,

the partia] cover 45' is installed during the heating-operation so as to 'limit the passage of gases directly to the main central flue 44 and insure that the desired portion of these will go down the central fiues 4| of the boxes 40. The blocks 23 which raise the steel bottoms above the floor ll are desirable to insure uniform heating oi' the lower coils and prevent cold bottoms which occur when the bases are placed directly on the floor.

While I have shown certain preferred forms of apparatus for carrying out my invention it is to be understood that the apparatus may be modifled to meet varying conditions and requirements and I contemplate such changes as come within the spirit and scope of the appended claim.

I claim:

A platform type annealing i'urnace, comprislng a platform of substantially circular shape having burners extending inwardly at its periphery, waste gas withdrawing means adiacent the center, an intermediate, circularly extending material receiving floor. cylindrical material receiving containers on said floor, said containers having central vertical fiues, connections below said. fiues to the central waste gas withdrawing means, and a removable cover seating on said platform.

GEORGE W. VREELAND.

CERTIFICATE OF CORRECTION Patent No. 2,162,lh5.

June 1939.,

GEORGE w. VREELAND.

It ie hereby certifed that error appears in the printed specification of the above numbered patent requiring correction as followe: Page l, first column, line 19, for the word "to" read in; page 2, first column, line 51 for "present" read prevent; and that the said Letters Patent shouldbe read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 25th day of July, A. D. 1959.

(Seal) Henry Van Arsdae,

Acting Commissioner of Patents.

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