US2172386A - Apparatus for treating metal sheets - Google Patents

Description

Sept. 12, 1939. E, I, HUFF 2,172,386

APPARATUS FOR TREATING METAL SHEETS Filed July 2'7, 1936 4 Sheets-Sheet l A Away/w? fiiiZ/a/ I E mm f Ha Sept. 1 1939. I E. I. HUFF 2,172,386

APPARATUS FOR TREATING METAL SHEETS Filed July 27, 1936 4 Sheets-Sheet 2 10/ Q 7/ 2 I /03 i I I I l I I I I l I I l I l I l I I I Lllllllllb @f M Y [Wm/ 5/:

Sept. 12, 1939. I E. I. HUFF 2,172,386

APPARATUS FOR TREATING METAL SHEETS Filed July 27, 1936 4 Sheets-Sheet 4 POWER 70 Mo role 8/ CMVEYE POWER SWITCH To M0701? 5.9

UPPER L/M/ T A REVEIPS/IVG 0PPER L/MITB m A LOWE? LIM/ TA LOWE F LIMIT SH/FI'ER LIMIT SWITCH SH/FIER PM 77MB? 3 T11R75 SEQUENCE COIITRULLER ssauzwce com-R04 M070)? /6/ mm: INTER VALS flaps w til Patented Sept. 12, 1939 UNITED STATES 2,172,386 APPARATUS FOR. TREATING METAL sHEE'rs Edward I. Huff, Reiffton, Pa., assignorto Hufl Equipment Company, Pittsburgh, Pa., a corporation of Pennsylvania Application July 27, 1936, Serial No. 92,725

- 9 Claims.

This invention is directed to apparatus for treating metal sheets, more particularly, to apparatus for the normalizing and annealing of metal sheets, in particular, steel sheets.

It has hitherto been the custom, in the continuous annealing or normalizing of steel sheets, to pass the sheets continuously through a furnace in a substantially horizontalposition. This practice has many disadvantages, among which may be mentioned the necessity for the use of dummy sheets, the necessity for providing water-cooled shafts for the rollers used, and the marking of the surface of the metal sheets being treated. It has been proposed, to avoid certain of the difliculties encountered in passing steel sheets through a furnace in a horizontal position, to pass the steel sheets through a furnace while the sheets are in a vertical position. However, while some of the disadvantages of horizontal treatment are avoided by such a procedure, serious difliculties in thesatisfactory treatment of the steel sheets still remain. Thus, for example, the steel sheets are marked by the clamps used to support them as they pass through the furnace. Moreover, the furnace construction necessary for the practice of this type of annealing, namely, a tunnel open at both ends, inevitably causes air currents'which result in uneven heating of the steel sheets being annealed. Consequently, the sheets are twisted and warped to some extent during the annealing process, and it has not been possible to produce a flat sheet uniformly annealed.

In accordance with my invention there is provided apparatus for the continuous annealing of, for example, sheet steel in which a uniform temperature is maintained throughout the furnace, and the steel sheet is supported in the furnace in a vertical position. without the use of clamps or any other device that would mark the surface of the annealed sheet. is a consequence, it is possible to obtain an annealed sheet that is unwarped, is uniformly annealed throughout, and is free from surface markings. Moreover, by the provision of automatic control means it is possible to insure an absolute uniformity in the annealing treatment given each sheet ofsteel, while nevertheless retaining the utmost flexibility in the temperature and time factors of the annealing process.

In accordance with my invention, the sheets of steel or other metal to be normalized or annealed are fed successively in position beneath the annealing furnace. Eachsheet in-succession is then automatically raised-up into position in the annealing furnace where it remains suspended vertically in the furnace until the desired heat treatment has been effected. The sheet is then lowered out of the furnace and automatically conveyed away from the furnace to a point 5 of discharge or to pickling, scrubbing vats, or the like.

The apparatus which is preferably utilized in accordance with my invention comprises a substantially completely enclosed annealing furnace 10 adapted to hold a single sheet'of steel or other metal to be treated suspended vertically therein and provided with, as the sole opening, a relatively narrow slot in the bottom of the furnace through which the sheets of steel may enter and 15 leave the furnace; a conveyor adapted to bring the sheets of steel successively into position beneath the furnace; hoisting means partially contained in the furnace for raising the steel sheets from the conveyor into the furnace and lowering them again after the heat treatment is over onto the conveyor; and meansfor loading the steel sheets onto the conveyor and removing them from the conveyor.

The preferred embodiment of my invention is shown in the accompanying drawings in which Fig, 1 is a front elevation, partly in section, of the apparatus in accordance with my invention, including the furnace conveyor and loading and unloading means. 30

Fig. 2 is an end view showing the discharge end of. the apparatus shown in Fig. 1.

Fig. 3 is a vertical sectional view through the apparatus shown in Fig. 1, looking toward the n charging end of the apparatus.

Fig. 4 is a detail view showing the upper end of a sheet of steel or other metal prepared for treatment in the apparatus shown in Fig. 1.

Fig. 5 is a detail view of the carrier bar utilized for supporting the sheets of steel during treatment.

Fig. 6 is a fragmentary, plan view of the seouene controller used in accordance with my invention for controlling the passage of the steel sheets through the apparatus.

Fig. 7 is a. plan view showing the time control device used for determining the interval of time during which the sheet steel remains in the furnace.

Fig, 8 is a diagrammatic wiring diagram showing the arrangement of interlocking controls used to secure proper sequence of operations and to prevent improper sequence of operations.

And Fig. 9 is a diagrammatic sketch showing the operation of the sequence control illustrated in Fig. 6.

As is best shown in Fig. 1, the apparatus in accordance with my invention comprises a furnace, indicated generally by the reference character I; a conveyor, indicated generally by the reference character 3, adapted to' bring sheets of steel successively into position beneath the furnace; a hoisting mechanism, indicated generally by the reference character 5, for raising the sheets of steel into the furnace and lowering them again onto the conveyor 3; a loading mechanism, indicated generally by the reference character 1, for feeding sheets of steel onto the conveyor 3; and an unloading mechanism, indicated generally by the reference character 9, for removing treated sheets of steel from the conveyor 3 and discharging them from the apparatus.

The furnace I is' enclosed in a welded steel shell II, which is supported in conventional manner from the buck-stays I3, the bottom tie members I5 and the top tie members I1. Inside the steel shell II is provided the usual heat insulating ma-. terial I9 and refractory material 2 I. A plurality of electric heating units 23 fixed on the interior wall of the heating chamber proper 25 provide the necessary heat. It will be noted that heating chamber 25 is substantially entirely enclosed, the

only opening therefrom being the relatively narnamed in the supporting members 41. Likewise.

fixed on the shaft 45, is a ratchet wheel 49, which is engaged by a lever 5|, acting as a pawl. Lever 5| is held against the ratchet wheel 49 by a spring 53 attached to the support 41, and is pivoted at its opposite end to the crank disc 55, which is driven through a reduction gearing 51 by the electric motor 59. Fixed on the same shaft as the crank disc 55 is a cam 6| adapted to actuate in its rotation control switch C, carried on the support 41, of the interlocking control circuit.

The hoisting mechanism 5 comprises a pair of drums or sprockets 1| mounted on a shaft 13 and enclosed in housings 15. The shaft 13 extends beyond the housing 15, across the top-of the furnace, and is driven through gears 11, 19 by the electric motor 8| supported on the top tie members I1 of the furnace. A pair of chains or cabies 93 are secured; to, and adapted to be wound on, the drums 1| and pass through openings in the roof of the heating chamber 25. Positioned within the heating chamber 25 andamxed to the lower ends of the chains or cables 33 is a carrier member 81 having inturned, concave flange elements 89 adapted to receive and hold thesheet metal carrier bar 9| shown in Fig. 5, which willbe hereinafter described.

Secured to one of the chains or cables are a pair of sleeve members 93 carrying a projection adapted to actuate the interlocking control switch E of the interlockingcontrol circuit. Sleeves 93 are capable of being adjusted along the chain or cable 83 so that one of them wil. trip or actuate the switch arm of switch E downwardly when the carrier 81 is in its lowermost position with the carrier bar 9| resting on the,conveyor 3, while the other sleeve 93 will trip the switch arm 95 upwardly when the carrier 81 is in its uppermost position adjacent the roof of the heating chamber 25.

The loading mechanism 1 and the unloading mechanism 9 are similar in construction and comprise cars IIII adapted to travel along the rails I93 positioned along the top of the. furnace I. Each car IIII carries an electric motor I95 anda drum I91 driven thereby. A pair of cables I09 are secured to and adapted to be wound on each of the drums I01. These cables pass from the drums I01 over pulleys III and are-fastened at their lower ends to the carrier II3. This carrier runs on rollers II5 within the track formed by channel members 1. Channel members I" are supported at their ifpper ends from the cars IIII and are free at their lower ends. The carrier I I3 is provided with apair of inturned concave flanges I I9, similar to those of the carrier 61, and adapted, like those of the carrier 31, to receive and support the carrier bars 9I.'

On one of the channel members 1- of the loading mechanism 1 there is provided a pair of interlocking control switches A and A. These switches are adapted to be tripped or actuated by the rollers N5 of the carrier II3. Switch A, positioned at the upper end of thechannel member.

H1, is adapted to be actuated by the carrier 3 when it is in its uppermost position, while switch A, positioned at the lowerend of channel member I |1,is adapted to be actuated when the carrier I I3 'is in its lowermost position. A similar pair of interlocking switches B and B are provided on one of the channel members II1 of the unloading mechanism 9.

Each of the cars IIII is pivotally connected to a pair of links I2 I, which in turn are pivotally connected, at their other ends, to a pair of crank discs- I23. The crank discs I23 are fixed on a shaft I25, which is journaled in the frame member I21 supported on the top tie members I1 of the furnace I.

Shaft I25 is driven through gears I29, I3| by elec-,

tric motor I 33. An arm or cam I35 is also fixed on the shaft I25 and is adapted to actuate, at every half revolution of the shaft I25, interlock control switch D.

A pair of links I4| are pivotally connected to the lower ends of the channel members I I1 of the unloading mechanism 9, and these links I are fixed at their other ends to stud shafts I43 journaled in the fixed frame member 41. Likewise fixed on the stud shafts I43 are gears I45 meshing with pinions I41 fixed on a second pair of stud shafts journaled in the fixed frame member 41. Fixed to these second stud shafts are a pair of fingers I49 adapted, when raised in position, to receive and hold a carrier bar 9|.

Positioned immediately beneath the fingers I49 and supported at its upper end by the fixed frame member 41 is a rollway I5I provided with a guide plate I53 and rollers I55.

The sequence control mechanism shown in Fig. 6 comprises an electric motor |6| which-drives, through reduction gearing I63, a drum I65. The drum-I65 carries on its surface a plurality of contact members or strips I61 extending for various distances about the periphery of the drum,.each of which is adapted to engage, on rotation 01' the drum, one of a plurality of fixed contacts I69. Y

' the drum I65 over that portion of one revolution of the drum represented by the heavy black lines.

In series with the switches closed or opened by the operation of the sequence control mechanism, as set' out above, are the several switches shown diagrammatically in Fig. 8, which switches are actuated, as shown in the figure, by the several interlocking control switches A, B, C, D, and E. It is accordingly apparent that before any particular motor or other actuating mechanism can be energized, it is necessary that both the sequence control mechanism in its operation shall have closed the switches for that circuit and that the switches controlled by the interlock control mechanism shall likewise be closed.

The timing device shown in Fig. '7 comprises a motor "I which drives through reduction gearing I13 the shaft I15, slidable along the shaft I15, but keyed thereto, is a friction wheel I11, which is in frictional engagement with the face of plate I19 secured to one end of shaft I8I. Disc I83 is mounted on shaft I8I and carries on its outer surface a contact member I85, which is adapted to engage, during a portion of the rotation of disc I83, fixed contact I81. Contacts I85, I81 are positioned in the circuit for the sequence control mechanism motor I5I,

and this motor consequently is energized onlywhen these contacts are closed.

The friction wheel I11 is movable along the shaft I15 and may be maintained in any desired position thereon by means of the guide member I89 which is threaded on the screw shaft I8I. A pointer I93, attached to guide I88, indicates on scale I95 the position'of friction wheel I11 along the shaft I15. Screw shaft I8I may be rotated by means of the knurled knob I81 affixed thereto.

In the treatment of metal sheets, for example, steel sheets, in accordance with my invention, the sheets are first sheared approximately I longer than the final length, and at the same 7 time a plurality of holes evenly spaced along the end of the sheet and of elongated form to allow for expansion are punched in this edge portion. Such a sheet is shownin Fig. 4, and is designated by the reference character 2!", the holes being indicated by the reference character 203. After the sheets have been treated in accordance with my invention, the sheets are sheared along the line 205, and the extra length having the holes punched in it is thus removed.

The steel sheets 2III are carried through the apparatus supported on carrier bar 8| (Fig. 5). The body portion of this carrier bar 9| is a channel section made of suitable material to withstand the temperatures to which it is subjected, and designed to absorb the least amount of heat possible. The web of the channel section will desirably be cored, cut or punched out, as shown at 209, in order to reduce the weight thereof. Hooks 201 are attached to the channel section, at properly spaced intervals to correspond with the holes 203 in the sheet steel, either by welding or by being clamped by nuts threaded on the shanks of the hooks.

In order to visualize the operation of the apparatus in accordance with this invention, let us assume that a sheet of steel 2IlI is being heated in the furnace chamber 25 and that the various elements are in the position shown in Fig. 1. It will be noted that there are a plurality of steel sheets I hanging in the pit below the furnace, supported from the carriers 9| resting on the conveyor 3. Those sheets of steel to the left of the furnace opening 21 have as yet not been heat treated, while those to the right of the furnace opening have been heat treated in the furnace. It will be seen that the heat given off by the treated sheets in the pit 26 is to a large extent absorbed by the untreated sheets which consequently receive a certain degree of preheating before being placed in the furnace chamber 25. The carrier II3 of the loading mechanism 1 is in its lowermost position with a bar carrier 8| resting in the flanges H8. The hooks 201 of this particular bar carrier 9| are firmly supported against the fixed bar 2 secured in the T-shaped supp l ing members 43. A fresh sheet of steel 2III is then manually placed on the hooks 281 of this bar carrier 8|.

In the meantime the motor I1I of the timing control mechanism has been running, and consequently the shaft I8I and the disc I83 have been rotating at a speed determined by the position of the friction wheel I11 along the shaft I15. When the steel sheet 2I)I within the heating chamber 25 has been in this chamber for the predetermined period of time for which the timing control mechanism has been set by adjustment of the friction wheel I11 by means of the knob I 91, the contacts I85 and I81 are closed through the rotation of the disc I83. these contacts are closed, the motor I 5| of the sequence control mechanism is started and drum I55 begins to rotate. This point is indicated in Fig. 9 by the first arrow at the top of the figure. As the drum I65 rotates, the circuit to the timer motor "I is broken, and the action of the timing device stops. At the same time the circuit to the chamber hoist motor 8| is closed and, the reversing switch and power switch controlling this motor, as shown in Fig. 8. being in the proper position by reason of the action of the interlock control contacts in the competion of the last cycle of operation, the motor 8| is energized to rotate the drums H and lower the carrier81 bearing the sheet 2M undergoing treatment.

This lowering action continues until the carrier bar 8| is deposited on the chains 3| of the conveyor 3 and until the carrier 81 has descended an additional distance suflicient to disengage the flanges 88 thereof from the bar carrier 8|. At

trolling the operation of motor 59.

The power switch controlling the operation of motor 55 being closed, the further rotation of drum I 55 of the sequence control mechanism closes the circuit leading to the conveyor motor 59 and energizes this motor. Crank disc 55 is thereby given one complete revolution, which motion is transferred to the ratchet wheel 48 by the action of arm 5|, and advances this ratchet wheel one notch, thereby moving the conveyor chains 3I a suflicient distance to bring the bar carrier 9i, on which is suspended the sheet of steel 20I next to be treated, directly above the flanges 89 of the lowered carrier 81. In the meantime, the cam Bl rotating with the crank disc 55 actuates the interlock control contact C. Actuation of this contact, as shown When in Fig. 8, results inclosing the control circuits completing a half revolution, move cars IIII along which (1) close the power switch in the circuit leading to motor- 8|, and (2) open the power switch in the circuit leading to motor 59, thus stopping further rotation oi the crank disc and further movement oi the conveyor 8.

The continued rotation of the drum I55 the sequence control mechanism again closes the circuit leading to the chamber hoist motor 8|, and

the power switch in this circuit having been closed 7 through actuation of contact C, motor 8| is again energized, this time serving to raise the carrier 81, which brings with it the bar carrier 9| and the sheet 2III to be treated, into the furnace chamber 25. As the carrier 81 reaches its uppermost position adjacent the top of the furnace chamber 25, the second sleeve 93 on the cable or chain 82 actuates the interlock control switch E, this time in an upward direction. Such aotu'ationoi the control switch E, as shown in Fig. 8, closes control circuits which (1) throw the power switch in the circuit to motor 8| 011, thus stopping the motor and the upward movement of the carrier 81, and (2) throw the reversing switch governing the operation of motor 8| from up to down position.

' As this is done, continued rotation of the drum I65 of the sequence control mechanism closes the circuit starting timer motor III which sets in operation the timing control mechanism that will serve to determine the period of time that this sheet 2! will remain in the furnace chamber 25. At the same time the sequence control mechanism closes switches in the circuits to the two motors I which control the loading and unloading mechanisms I and 9. The power switches for these motors controlled by the interlock control mechanism being in closed position, and the reversing switch therefor being set in position for upward movement, these motors are energized to draw the carriers I I8 upwardly. This action raises the fresh sheet of steel that had been manually placed on the hooks 201 of the bar carrier 9| resting against the stop 2| I up between the channel members I I1 01 the loading mechanism and at the same time raises the treated steel, sheet in the extreme right position on the conveyor 3 up between the channel members III of the unloading mechanism 9. As the two carriers 8 reach their uppermost position within the channel members II I, they actuate interlock control switches A and B, respectively. The actuation of control switch A, as shown in Fig. 8, throws the power switch in the circuit controlling the operation of the corre-' sponding motor I 05 into off position, thus stopping the upward movement of the corresponding carrier II3. Similarly the actuation of switch B throws the power switch and the-circuit controlling the operation of that motor I95 into off position. When both switches A and B have thus been actuated, the reversing switch'in the circuit to motors I0! is thrown from up to down position, and the power switch in the circuit leading to motor I38 is thrown into closed position.

Continued rotation of the drum I85 01 the sequence control mechanism closes the circuit lead-' ing to motor I38, and the power switch controlled by the interlock control mechanism in this circuit having already been closed by the action of control switches A and B, thismotor I88 is energized. Crank discs I 28 are thereby rotated until the operation of cam I35 actuates interlock control switch D, which de-energizes motor I88 and stops the rotation of the crank discs I18 .after they have the rails III3 by means oi? the connecting links I2I to the position shown by the dotted lines in Fig. 1. The operation oi switch D, as shown in Fig. 8, in addition to throwing the power switch in the circuit leading to motor I88 into oi! position, also throws the power switches leading to'motors I05 and motor 8| into on, or closed, position.

Continued rotation of the drum I55 of the sequence control mechanism operates to energize once more motors I05. This time, by reason of the actuation of the reverse switches through the interlock control mechanism, in a direction to lower the carriers H3. The bar carrier 9I and the steel sheet 20I carried by carrier I I3 01! the loading mechanism I is thereby deposited at the extreme left end of conveyor 3, while the bar 9| and steel sheet 2III carried by the .unloading mechanism 9 is deposited on the fingers I49, which have been raised into horizontal position by the movement of channel members II'I into the position shown by the dottedlines in Fig. 1. As the respective carriers II3 reach their lowermost position, they actuate interlock control switches A and B, which, as shown in Fig. 8, de-energize the motors I05, throw the reversing switch governing the operation of these motors from down to up position, and throw the power switch of the circuit leading tomotor I 33 from oil to on position.

Continued further rotation of the drum I55 then again energizes motor I33 to cause the crank discs I23 to undergo a further half revolution with the resultant movement of cars IIII and the loading and unloading mechanism carried back into the position shown in the solid lines in Fig. 1. Therotation of crank discs I23 is stopped after one-half revolution by actuation of interlock control switch D, as-described above, and the conse quent de-energization of motor I88.

-The continued rotation of drum I65 then operates to open the circuit leading to motor IGI thus stopping further operation 'of the sequence control mechanism. The timing control mechanism, however, continues to run until, after the sheet I has been in the heating chamber I for the predetermined period'of time, the sequence control motor is started thereby, and the entire sequence of operations justdescribed is. repeated.

As channel members III of the unloading mechanism 9 move back into the position shown in the solid lines in Fig. 1, as just described, the fingers I49 are dropped from their horizontal position into the position shown in the solid lines in Fig. 1, and' the bar carrier 9| and steel sheet '2III supported thereby are permitted to slide down the rollway I5I.

It will be seen that in the operation just described-in detail abovethat a sheet of steel is taken by the loading mechanism I, raised, brought into position over the end 01' conveyor 3, and lowered into position on the conveyor, wh le at the same time, atthe right hand side of the conveyor a treated sheet has been raised from the conveyor, moved over above the fingers I49, and then lowered and discharged from the apparatus along the rollway I5I. Meanwhile, the chamber hoist mechanism I5 has picked up a bar carrier 9| and steel sheet "I from the,

completed a halt revolution. Crank discs I23, in has then been moved forward so as to bring the 7 next sheet of steel under the opening 21.' Ultimately the sheet of steel placed by the loading mechanism at the extreme left end of conveyor 3 will be brought beneath the furnace, raised up and heat treated in the furnace, lowered back on the conveyor, moved to the extreme right hand position on conveyor 3, and discharged from the apparatus by unloading mechanism 9.

It will be appreciated that, if desired, the unload'ng mechanism 9 may place the heat treated steel sheets directly on another chain conveyor similar to the conveyor 3, which will carry them to or through any suitable after treatment, such as pickling, scrubbing, etc. It will also be appreciated that any desired pre-treatment may be given the steel sheets, and that the mechanism 1 may be designed to pick up from a chain conveyor the sheets of steel that have undergone such pre-treatment and place them, as described, on the conveyor 3.

It will further be appreciated that, while an electrically heated furnace I has been described, that such furnace may, within the scope of this invention, be heated in any conventional manner, as by gas and the like.

Many other modifications of my invention will be apparent to those sk lled in the art, and it is accordingly to be understood that my invention is not to be treated as limited to the particular details of construction and operation set out above.

What I claim and desire to protect by Letters Patent is:

Apparatus for the treatment of metal sheets including in combination a furnace having a heating chamber open only at the bottom thereof and adapted to receive at least a single sheet of metal positioned vertically, a pit positioned beneath said furnace, a conveyor traveling beneath said furnace and above said pit, means for moving said conveyor intermittently, a plurality of carrier bars adapted to rest transversely on said conveyor and provided with means attachable to an edge of a metal sheet to be treated,

wherebya plurality of metal sheets may hang vertically in said pit suspended from said carrier bars resting on said conveyor, a carrier normally positioned in said furnace chamber and adapted to engage any of said carrier bars, means for lowering said carrier from said furnace chamber into proximity to said conveyor and for raising it into said chamber again, whereby a carrier bar and attached metal sheet may be raised from said conveyor into the furnace chamber and replaced on said conveyor again, hoisting means adapted to place a carrier bar and attached metal sheet on said conveyor adjacent one end thereof, and hoisting means adapted to remove a carrier bar and attached metal sheet from the conveyor at the opposite end thereof.

2. Apparatus for the treatment of metal sheets including in combination a furnace having a heating chamber open only at the bottom thereof and adapted to receive at least a single sheet of metal positioned vertically, a pit positioned beneath said furnace, a conveyor traveling beneath said furnace and above said pit, means for moving said conveyor intermittently, a plurality of carrier bars adapted to rest transversely on said conveyor and provided with means attachable to an edge of a metal sheet to be treated, whereby a plurality of metal sheets may hang vertically in said pit suspended from said carrier bars restengage any of said carrier bars, means for lowering said carrier from said furnace chamber into proximity to said conveyor and for raising it into said chamber again, whereby a carrier'bar and attached metal sheet may be raised from sa d conveyor into he furnace chamber and replaced on said conveyor again, hoisting means adapted to place a carrier bar and attached metal sheet on said conveyor adjacent one end thereof, and hoisting means adapted to remove a carrier bar and attached metal sheet from the conveyor at the opposite end thereof, at least one of said two last named hoisting means comprising a track positioned above said furnace and extendng longitudinally of said conveyor, a car adapted to run on said track, hoist mechanism mounted on said car, a pair of spaced guide members attached to said car and extending vertically beneath the car into proximity to saidjonveyor, a carrier adapted to engage any of said carrier bars connected to said hoist mechanism and adapted to run between said guide members, and means for moving said car along said track.

3. Apparatus as defined in claim 1 including in addition control means adapted to effect automatically in predetermined sequence and at predetermined intervals the operation of the mechanism described in said claim.

4. Apparatus as defined in claim 1 including in addition control means adapted to effect automatically in predetermined sequence anckat predetermined intervals the operation of the mechanism described in said claim and independent interlock control means adapted to prevent positively the effecting of an operation designed in normal sequence to succeed a preceding operation until such preceding operation shall have been completed.

5. Apparatus for the treatment of metal sheets including in combination a furnace having a heating chamber open only at the bottom thereof and adapted to receive at least a single sheet of metal positioned vertically, a conveyor traveling beneath said furnace, means for moving said conveyor intermittently, a plurality ofcarrier bars adapted to rest transversely on said conveyor and provided with means attachable to an edge of a metal sheet to be treated, whereby a plurality of metal sheets may hang vertically suspended from said carrier bars resting on said conveyor, a carrier normally positioned in said furnace chamber and adapted to engage any of said carrier bars, means for lowering said carrier from said furnace chamber into proximity to said conveyor and for raising it into said chamber again, whereby a carrier bar and attached metal sheet may be raised from said conveyor into the furnace chamber and replaced on said conveyor again, means adapted to place a carrier bar and attached metal sheet on said conveyor adjacent one end thereof, and means adapted to remove a carrier bar and attached metal sheet from the conveyor at the opposite end thereof.

6. Apparatus as defined in claim 5 including in addition control means adapted to effect automatically in predetermined sequence and at predetermined intervals the opcration of the mechanism described in said claim.

'7. Apparatus as defined in claim 5 including in addition control means adapted to elfect automatically in predetermined sequence and at predetermined intervals the operation of the mechanism described in said claim and independent interlock control means adapted to prevent positively the eiiecting of an operation designed in normal sequence to succeed a preceding operation until such preceding operation shall have been completed.

8." Apparatus for the treatment of metal sheets including in combination a furnace having a heating chamber open only at the bottom thereof and adapted to receiveat least a single sheet of metal positioned vertically, a conveyor traveling beneath said furnace, a plurality of carrier bars adapted to rest on said conveyor and provided with means attachableto an edge of .a metal sheet to be treated, whereby a plurality of metal sheets may hang vertically suspended from said carrier bars resting on said conveyor, a carrier normally positioned in said furnace chamber and adapted to engage any of said carrier bars, means (or lowering said carrier from said furnace chamber into proximity to saidfurnace chamber'and replaced on said conveyor.

again, means adapted to place a carrier bar and attached metal sheet on said conveyor adjacent one end thereof, and means adapted to remove a carrier bar and attached metal sheet from the conveyor at the opposite end thereof.

9. Apparatus for the treatment of metal sheets including, ,in combination, a furnace having a heating chamber provided with a narrow opening at the bottom adapted to permit the passage of a single sheet 0! metal positioned verticaliy, a conveyor traveling beneath said furnace, a plurality of carrier bars adapted to rest on said conveyor, each provided with means attachable to an edge oi a metal sheet to be heated and adapted to hold only a single sheet, whereby a plurality of metal sheets may hang vertically conveyor, means adapted to engage any one of said carrier bars to raise it with its attached metal sheet from said conveyor through said narrow opening into saidfurnace chamber and to replace it in similar manner on said conveyor the conveyor at the opposite end thereof;

EDWARD r. HUFF.

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