US2499846A

US2499846A - Annealing apparatus

Info

Publication number: US2499846A
Application number: US690635A
Authority: US
Inventors: Roy E Carter
Original assignee: Individual
Current assignee: Individual
Priority date: 1946-08-15
Filing date: 1946-08-15
Publication date: 1950-03-07
Anticipated expiration: 1967-03-07

Description

March 7, 1950 R. E. CARTER 2,499,846

ANNEALING APPARATUS Filed Aug. 15, 1946 3 Sheets-Sheet 1 IN V EN TOR.

B Roy E. Cari'er AT TORNEVS March 7, 1950 R E, CARTER 2,499,846

ANNEALING APPARATUS Filed Aug. 15, 1946 3 Sheets-Sheet 2- By Ray E. CaPier ATTORNEYS v Marh 7, 1950 CARTER 2,499,846

ANNEALING APPARATUS Filed Aug. 15, 1946 3'Sheets-Sheet 3 INVENTOR.

By Roy E. Carfier M ww ATTORNEYS Patented Mar. 7, 1950 UNITED STATES PATENT OFFICE ANNEALING APPARATUS Roy E. Carter, Warren, Ohio Application August 15, 1946, Serial No. 690,835

My invention relates to processes and apparatus for annealing metal sheets and particularly steel sheets in a sealed furnace compartment formed by outer furnace walls within which a stack of the metal sheets is located and constitutes a mass of metal over which is placed a sealed inner cover. Heat is introduced into the furnace compartment by means of burners 4 Claims. (Cl. 263-43) of which the annealing or heat treating of the stack of metal sheets is effected in an improved manner as compared with prior practice.

The foregoing and other objects are attained by the improved processes, process steps, apparatus, parts, combinations, and sub-combinations of the present invention, the nature of which located in the outer furnace side walls, the burners being supplied with fluid fuel, usually gas.

Prior to the present improvements, in such an annealing furnace there has been a non-uniform heating of the stack of metal sheets, the upper portions of the stack reaching the desired temperature before the lower portions, and a prolonged heating period has been required to bring the lower portions of the stack of metal sheets up to the desired temperature. The reasons for the non-uniform heating of the stack of metal sheets or charge in the usual annealing furnace include flame and heat distribution in the furnace compartment which in the early part of the heating cycle of any particular charge passes by the lower portions or bottom of the furnace compartment, and the bottom of the charge, and first heats up the top of the furnace compartment and charge.

For example, in many usual portable annealing furnaces each burner has a horizontal direction of flame motion from the nozzle of the burner in One of the outer furnace side walls, and this horizontally directed flame strikes a baffle tile or catalyst having a vertical face in the furnace compartment immediately in front of the burner nozzle. The horizontally directed flame strikes the vertical baille face and rises immediately towards the upper portions of the furnace compartment with slight heating effect upon the bottom of the charge. Moreover, such baflles mounted directly in front of a burner ejecting a horizontally directed flame are often broken or knocked out.

The objects of the present improvements include the provision of improved processes and apparatus for effecting in an annealing furnace of the type described uniform and rapid heating of astack of metal sheets from the bottom to the top, the heating of the stack of metal sheets or charge being initiated at the bottom of the charge from the beginning and throughout the heat cycle, whereby an equilibrium of top and bottom temperatures in the furnace compartment and charge is reached very rapidly, and a relatively short heat cycle for the complete annealing or heat treatment is attainable, with -a consequent saving in fuel consumption, as compared with usual annealing or heat treating processes and apparatus.

Further objects of the present improvements include the provision of annealing furnace apparatus including improved and novel details of construction and arrangement by the operation is set forth in the following general statement, and preferred examples and embodiments of which together with their mode of use are set forth in the following description, and which are particularly and distinctly pointed out and set forth in the appended claims forming part hereof, or in claims which may originate herein.

The nature of the processes of the present improvements may be stated in general terms as including in a furnace compartment for annealing and the like, breaking up and catalyzing a flame jet at the bottom of the compartment so as to initiate heating at the bottom and rapidly attain temperature equilibrium from bottom to top of the furnace compartment and charge therein.

The nature of the apparatus of the present improvements may be stated in general terms as including walls forming a furnace compartment,

- a flame jet target wall in. a lower portion of the furnace compartment, and means for impinging a flame jet against the target wall, the flame jet and target wall being arranged with respect to each other so as to initiate heating and flame distribution at the bottom of the furnace compartment and charge therein.

By way of example, embodiments of the improved apparatus and parts hereof adapted for carrying out the improved processes and process steps hereof are illustrated in the accompanying drawings forming part hereof in which Figure 1 is a fragmentary transverse vertical cross section as on line l--I Fig. 2 of an annealing furnace including the present apparatus improvements and adapted for carrying out the improved process steps hereof;

Fi-g. 2 is a reduced vertical longitudinal section thereof as on line 2-2, Fig. 1; and

Fig. 3 is an enlarged fragmentary view similar to Fig. 1.

. In Figs. 1 and 3 the stack of metal sheets and the inner cover are shown, while in Fig. 2 the furnace is shown without either the stack of metal sheets or the inner cover.

Similar numerals refer to similar parts throughout the drawings. I

The improved annealing furnace indicated generally by ID includes a composite rectangular bottom wall indicated generally by II, opposite laterally spaced composite side walls indicated generally by Na and 12b, opposite longitudinally spaced composite end walls indicated generally by In and l2d, and a composite rectangular top wall indicated generally by It.

Side and end portions of the walls II, In, ltb,

I20, I2d, and I3 are in sealing engagement with each other when the furnace is in use, and form a sealed furnace compartment I4. As shown and preferably, the composite bottom wall II is separable from the side and end walls I2a, I2b, I2c, and I2d, and the top wall I3, which are connected with each other and carried by a structural framework indicated generally by I5, having a central upper lifting yoke I6, whereby the side and end walls I2a, I2b, I20, and IM and the top wall I3 may be lifted bodily from the bottom wall I I, by means of a crane.

In other words, the connected side and end walls I2a, I2b, I20, and I2d, and top wall I3 form an inverted box having a lower opening, bounded by the lower faces of the side and end walls I201, I21), I20, and I2d, these lower faces seating upon top border portions of the rectangular bottom wall II to form the sealed furnace compartment I4 as illustrated, and there being usual sand seal means indicated generally by II at the joints between the lower faces of the side and end walls I2a, I21), I20, and I2d, and the bottom wall II.

The composite bottom wall I I as shown includes a lower metal pan I8 opening upwardly and preferably formed of sheet metal, and preferably as shown being provided with inner downwardly opening rectangular reinforcing channel ribs I9. In the pan I8 are located a plurality of horizontal layers of refractory brick 20. On top of a top layer of the refractory brick 20 bounded by the channel ribs I9, there is supported a plurality of laterally extending side by side steel rails 2I on the top of which is supported a plate 22, the rails 2| forming a plurality of horizontal flues 2 I-I therebetween.

When the furnace is in use as shown in Figs. 1 and 3, a stack of metal sheets 23 are supported on the steel plate 22. The improved furnace I is particularly adapted for use in annealing steel sheets, and the metal sheets 23 may therefore in many instances be steel sheets. An inner inverted box cover 24, usually made of sheet steel, is placed over the stack of metal sheets 23, and the lower edges of the side and end walls of the Inner box cover 24 seat on upper faces of the channel ribs I9, and form therewith and with side walls 26a and 25b and end walls 280 and 26d each projecting upwardly from a lower layer of the brick 20 above the top of the top layer of brick 20 in the composite bottom wall I I, a channel filled with sand 25 which provides a sand seal for the inner cover 24.

The inverted box inner cover 24 includes opposite spaced side walls 21a and 21b, the inner cover side wall 21a being opposite the outer furnace side wall I2a, and theupwardly projecting wall 26a is laterally spaced from and extends longitudinally between the outer furnace wall I2a and the inner cover wall 21a. Similarly, the inner cover wall 21b is located opposite the outer .furnace wall I21; and the upwardly projecting wall 26b is laterally spaced from and extends longitudinally between the walls 21b and I2b.

The upwardly projecting wall 23a constitutes a burner target wall, and for the purposes of the present improvements preferably is provided with an outer longitudinally extending side deflector face 23a which slopes from bottom to top towards the inner cover wall 21a. Similarly, the upwardly projecting wall 26b constitutes a burner target wall and is provided with an outer longitudinally extending side deflector face 23b which rectangular steel slopes from bottom to top towards the inner cover wall 21b.

The composite side andend walls I21: and I2!) each include as shown an outer sheet metal wall 23 and an inner refractory brick lining wall 33. The composite top wall I3 as shown includes an inner refractory brick arch wall 3| and an outer refractory cover wall 32.-

In the lower portion of the outer funace side wall I2a are mounted a plurality of high velocity gas burners each indicated generally by 33, and similarly a plurality of the burners 33 aremounted in the lower portion of the outer furnace side wall I2b. Each burner 33 includes an inner elongated nozzle tube 34, preferably a venturi, having a longitudinal axis 35 which is the axis of the flame jet emitted from the burner tube 34 within the furnace compartment I4. Each tube and flame jet axis 35 slopes from the top downwardly towards the bottom wall II and intersects the deflector face 28a or 2812 of one of the target walls 26a or 251). Each burner 33 is a high velocity fluid fuel burner, preferably supplied with gas through usual supply pipe line means 36 as shown in Fig. 3. A pilot burner indicated generally by 31 is preferably provided for each high velocity burner 33.

In the operation of the improved annealing furnace I II for carrying out the improved processes hereof the flame jet from each burner 33 strikes against one of the deflector faces 28a or 23b of one of the target walls 26a or 261), where the flame jet is broken up and catalyzed and immediately initiates heating of the bottom of the furnace compartment and of the stack of metal sheets or charge 23, the

target walls

26a and 26b rapidly rising in temperature and heat being transmitted by conduction from the

target walls

26a and 26b and through the refractory brick 20 and metal channel ribs I9 in the composite bottom wall II to the side by side rails 2I with the horizontal flues 2 I-I therebetween. These flues 2I-I have open ends and the gases within the inner cover 24 circulate through the horizontal flues under and then around the sheet stack or charge 23, and the heat transmitted to the side by side rails 2I is in turn immediately transmitted to the bottom of the sheet stack or charge 23. The broken up flame jets striking the deflector faces 23a and 28b of the target walls 23a and 26b on the outside of the inner cover are distributed throughout the furnace compartment I4 between the outer furnace walls and the inner cover 24, the flow of the distributed flame or combustion gases being upwardly along the side and end walls of the inner cover 24 across the lower face of the top wall I3, and down along the inner faces of the (lllzlgel' cover side and end walls I2a I21), I20, and

The heat flow and distribution in the charge and in the combustion gases in the furnace compartment I4 is thus initiated at the bottom of the charge and of the furnace compartment and very quickly reaches an equilibrium condition from bottom to top, so that time of the heat cycle required for each charge is reduced considerably as compared with usual practice, and a substantial saving in fuel is effected.

It is further noted that the rails 2I and plate 22 forming the dues 2I-I, and the sheet stack or charge 23 supported on the plate 22, are all in a sealed inner compartment formed by the inner cover 24 and the composite bottom wall II and the sand seal therebetween. This sand seal, as

above stated, is formed by sand 25 filling the channel formed by the lower edges of the side and end walls of the inner box cover 24, and by upper faces of the channel ribs [9 on which the lower edges of the side and end walls of the inner box cover 24 are seated, and by the upwardly projecting burner

target side walls

26a and 26b and the upwardly projecting end walls 260 and 26 d.

Within this sealed inner compartment the above described heating of the bottom of the sheet stack or charge 23 and circulation of the gases under and then around the sheet stack or charge 23 takes place simultaneously with the distribution of combustion gases from bottom to top of the outer furnace compartment l4 and the flow of the combustion gases therein produced by the flame jets of the burners 33 being directed downwardly and inwardly and striking the defiector faces 28a'and 28b of the

target walls

26a and 26b. I

The furnace I 0 is preferably provided with exhaust means for the burned gases in the furnace compartment l4, and the exhaust means preferably include a plurality of covered intake heads, each indicated generally by 38 and located in the furnace bottom wall ll. These intake heads 38 communicate through fiues below the furnace bottom wall H to a common stack, and eliminate the discharge of the spent combustion gases into the building in which the furnace I0 is located, as is usual practice. The discharge of the gases of combustion from annealing furnaces directly into the building in which they are located is objectionable, particularly to the operators of the travelling cranes which are used to raise and lower the outer furnace covers and the stacks of steel sheets, in charging and discharging the furnaces.

Each intake head 38 as shown includes an upper dome cover 39 and a vertically extending tube 40 having an upper end portion protruding above the furnace bottom wall H and into the lower portion of the furnace compartment l4, each cover 39 extending over with substantial clearance and being supported on the upper extremity of the associated tube 40. Each tube 49 constitutes a flue tube extending vertically through the furnace bottom wall i I, and as shown being made of metal. Each dome cover 39 has its lower edge located closely adjacent the top of the bottom wall I I, whereby the exhaust gases are forced to travel along the bottom wall to exit through the tube 40. v

The steps and embodiments of the present improvements described herein are by way of example, and the scope of the present invention is not limited to the same orto the particular details thereof but is commensurate with any and all novel subject matter contained herein which may at any time properly under the United States patent-laws be set forth in the claims hereof or originating herein, and the elements of any such claims are intended to include their reasonable functional and structural equivalents.

I claim:

1. In a furnace for annealing and the like, walls forming an inner sealed compartment and walls forming an outer sealed compartment extending around walls of the inner compartment, the compartments having a common bottom wall including a. plurality of members in heat conducting association with each other, some of the heat conducting members forming flues within the inner compartment, the flue forming common bottom wall members within the inner compartment being adapted to support a charge of material, and means for introducing and directing a flame jet downwardly into the outer compartment so as to strike the common bottom wall in the outer compartment adjacent another wall of the inner compartment.

2. In a furnace for annealing and the like, walls forming an inner sealed compartment and walls forming an outer sealed compartment extending around walls of the inner compartment, the compartments having a common bottom wall including a plurality of members in heat conducting association with each other, some of the heat conducting members being spaced from each other within the inner compartment, the spaced common bottom wall members within the inner compartment being adapted to support a charge of material, and means for introducing and directing a flame jet downwardly into the outer compartment so as to strike the common bottom wall in the outer compartment adjacentanother wall of the inner compartment.

3. In a furnace for annealing and the like, walls forming an inner sealed compartment and walls forming an outer sealed compartment, the compartments having a common bottom wall including a plurality of members in heat conducting association with each other, some of the heat conducting members being spaced from each other within the inner compartment, the spaced common bottom wall members within the inner compartment being adapted to support a charge of material, one or more of the heat conducting members of the common bottom wall projecting upwardly in the outer compartment adjacent a wall of the inner compartment, the upwardly projecting common bottom wall members constituting a target, and means for introducing and directing a flame jet downwardly into the outer compartment so as to strike the heat conducting target members of the common bottom wall.

4. In a furnace for annealing and the like,

walls forming an inner sealed compartment and walls forming an outer sealed compartment extending around walls of the inner compartment, the compartments having a common bottom wall including a plurality of members in heat conducting association with each other, some of the heat conducting members being spaced from each other within the inner compartment, the spaced common bottom wall members within the inner compartment being adapted to support a charge of material, and means for introducing and directing a flame jet downwardly into the outer compartment so as to strike the common bottom -.wall in the outer compartment.

ROY E. CARTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Industrial Furnaces, Vol. 11 by w. Trinks, 2nd. edition 1942. page 244, Fig. 245.