US2496914A - Heating furnace - Google Patents

Description

Febv 7, W50 F. o. HESS 2,496,914

HEATING FURNACE Filed Sept. 26, 1946 2 Sheets-Sheet l INVENTOR.

' Feb. 3/, 1950 F. o. HESS 96,914

- HEATING FURNACE Filed Sept. 26, 1946 2 Sheets-Sheet 2 MATTOW/VE) Patented 7, 1950 UNITED STATES PATENT OFFICE HEATING FURNACE Frederic 0. Hess, Philadelphia, Pa., assignor to Selas Corporation of America, Philadelphia, Pa., a corporation of Pennsylvania Application September 26, 1946, Serial No. 699,417

8 Claims.

This invention relates to heating furnaces and is especially concerned with such furnaces in which work pieces and articles of elongated extent, such as tubing, bars, rods and the like, are transported lengthwise through the furnace for progressively heating work pieces in a controlled manner to a desired elevated temperature.

It has already been proposed to heat work pieces or stock of elongated extent by moving the Work in single line transit and in endless procession through one or more furnace units for progressively heating successive longitudinal portions of the work to a high temperature. When it is desired to heat wc'k rapidly in single line transit, the furnace unit or units are preferably of a type in which a high thermal head is produced by an immense heat release closely fitting about the travelling work pieces.

When the heating furnace comprises a number of furnace units, such units are in end to end relation and relatively close together. With such an arrangement the heated furnace gases discharged through the exit and entrance openings of adjacent furnace units form a high temperature gaseous atmosphere which blankets the Work and protects the latter while successive portions of the work pass from one furnace unit to a succeeding furnace unit. In this manner work or stock of elongated extent can be heated at such rates that a considerable weight of stock can be handled in single line transit at a relatively high rate of speed through one or more such furnace units.

In many heating operations where it is desired to heat work of elongated extent in single line transit, the speed at which the work must be moved is so high that a heating furnace of prohibitive length is required to accomplish the requisite heat treatment. In other words, while it is possible to construct a single heating furnace or a number of furnace units in end to end relation to heat treat work in single line transit to take care of exceptionally rapid speeds at which the work must sometimes be moved, such heating furnaces or furnace units often are costly and expensive and require an unduly large amount of plant space.

In accordance with this invention, an improved heating furnace is provided with embodies all of the desirable qualities of heating furnaces now employed for heating elongated work or stock in single line transit, such improved furnace not only being considerably smaller in size compared to existing heating furnaces of comparable capacity, but also capable of heating 2 work or stock in single line transit at higher speeds than heretofore possible. The principles of the invention may be embodied in a, single heating furnace or a number of furnace units in end to end relation, and in either case the actual time during which work is under heat treatment is relatively short compared to batch heating of Work and the deleterious effects of time-at-temperature, such as scaling and decarburiz'ation, are minimized.

This is accomplished by providing mechanism for supporting a number of elongated work pieces alongside of each other and transporting and advancing such work pieces in a battery lengthwise through a heating furnace which may comprise a single unit or a number of units in end to end relation. The work pieces are fed lengthwise in single line transit and in rapid succession to a first region of the heating furnace where the transporting mechanism is effective to advance the work pieces; and the heated work pieces are discharged lengthwise in rapid succession and leave the transporting mechanism at a second region of the heating furnace which is laterally removed from the first region at which'the incoming Work pieces are received. While the battery of work pieces is being advanced lengthwise through the heating furnace by the transporting mechanism, the work pieces are bodily shifted sideways in one or more steps from the incoming first region, whereby successive work pieces will be at the second region when ready to be discharged from the heating furnace.

In the heating furnace of the invention the elongated Work pieces are heated for substantially the same interval of time during movement through the furnace, whereby substantially uniform heating of successive longitudinal portions of all work pieces to the same elevated temperature is automatically effected. Further, the work pieces can be fed lengthwise to and removed lengthwise from the heating furnace at exceptionally high rates of speed while the work pieces in the heating furnace can be transported lengthwise at a considerably slower speed. By being able to move the work pieces at a considerably slower rate in the heating furnace while equipment but also providing such equipment which will ocupy a minimum amount of space.

The invention, together with the objects and advantages thereof will be more fully understood upon reference to the following description taken in conjunction with the accompanying drawings forming a part of this specification, and of which:

Fig. 1 is a top plan view more or less diagrammatically illustrating a number of furnace units embodying the invention, such furnace units be ing arranged relatively close together in end to end relation for work or stock of elongated 'extent to pass lengthwise therethrough to effect the desired heating of the work{ Fig. 2 is an enlarged fragmentary side elevation of the furnace units shown in Fig. l to illustrate more clearly details of the mechanism disposed between adjacent furnace units for sup porting and transporting the work or stock therethrough;

Fig. 3 is an enlarged fragmentary vertical sectiona1 view of the ends of adjacent furnace units shown in Figs. 1 and 2 to illustrate the in vention more clearly;

Fig. 4 is a transverse sectional view taken at line 4-4 of Fig. 3;

Figs. 5 and 6 are fragmentary transverse sectional viewssimilar to Fig.4 to illustrate more clearly the mechanism for shifting the work or stock sideways within the furnaces; and

Fig. 7 is a sectional view more or less diagrammatically illustrating the type of roller disposed between each pair of adjacent furnace units for transporting the work or stock lengthwise through the furnaces.

Referring to Figs. 1 to 3 inclusive, 1 have shown my invention as'applied to a heating furnace comprisin a number of furnace units II! which are relatively close together in end to end relation and through which work or stock II, such as bars or tubes and the like, for example, of elongated extent is transported for heating successive longitudinal portions'thereof to a desired elevated temperature. As best shown in Fig. 3, the furnace units ID are provided with refractory'lined chambers I2 which are relatively small in transverse section and formed with elongated aligned openings I4 and I5. in the end walls through which the work II enters and leaves each chamber. To produce a high rate of hatliberation in as small a space as possible, a number of burners I6 are crowded and incorporated in'the opposing side walls of each chamber I2.

The refractory walls I1 defining the chambers I2 are formed of suitable refractory material capable of withstanding the high temperatureSprQ- duced in the chambers. The refractory walls I! are encased in outer metallic shells I8 adapted to be supported in any suitable manner. The outer shells I8 may include hollow end sections I9. through which a cooling medium, such as water, for example, is circulated (not shown) to effect cooling and prevent undesirable overheating of the end walls.

As best shown in Fig. 4, suitable connections are provided for individually supplying a combus tible fuel mixture to each burner I6. The cornbustible fuel mixture may be delivered from a source of supply to manifolds 2i! to which are connected conduits 2I communicating with the burners I6. Suitable controls, including valves 22 connected in the conduits 2| be provided to control the pressure and rat at which the combus- 4 tible fuel mixture is individually supplied to each burner I6.

The burners I6 preferably are of a direct fired type capable of producing high heating temperatures in the chambers I2. Although not to be limited thereto, burners which have been found especially suitable are of the kind described and illustrated in Hess Patent No. 2,215,079, granted on September 17, 1940, and, if desired, reference may be had thereto for a detailed description of the burner structure.

In compact furnace units of the kind just described, the work or stock II is heated rapidly by the heating effects produced within the chambers I2. Such heating effects include both radiant and convection heating components. When high temperature heating effects are required to heat successive longitudinal portions of the work II rapidly to the desired elevated temperature, the high temperature products of combustion or furnace gases whip through the furnace chambers I2 at a relatively high velocity. Such furnace gases pass through the openings I4 and I5 and produce what is often referred to as a sting out; that is, a gaseous atmosphere is roduced which envelops the work as it passes from one furnace to the next succeeding furnace.

The work pieces II, which are of longer length than the individual furnace units ID, are transported through the furnaces If! by conveyor rollers 23 disposed in the gaps between adjacent furnaces. As best shown in Fig. 7, the rollers 23 are hollow and formed with a number of grooves 24 adjacent to one another for simultaneously moving a battery of elongated work pieces at the same time through the furnace units 20. The ends of the rollers 23 are fixed to hollow stub shafts 25 journaled in bearings 26 provided at the upper ends of standards 27 which are supported in any suitable manner between adjacent furnace units IIl. Rotary union connections 28 are provided at the ends of the shafts 25 to which flexible conduits 29 are connected for circulating a coolant, such as water, for example, through the hollow shafts 25 and rollers 23 fixed thereto.

The rollers 23 may be driven in any suitable manner. As shown in Figs. 2 and 4;, the rollers 23 may be driven by endless chains 30 connected to gears 3| and 32 fixed to the shafts 25 and to shafts 33, respectively, the latter being journaled in brackets 34 extending downwardly from the ends of the furnaces Ill. The shafts 33 are provided with gears 35 which are interconnected by endless chains 36, as shown in Figs. 2 and 4, and may be driven by a single electric motor (not shown).

In accordance with this invention the elongated work pieces II are supported alongside. of each other by the rollers 23 and advanced lengthwise through the furnace units I f! as a unitary group. As best shown in Fig. 1, the work pieces II are fed lengthwise in single line transit and in rapid succession to a first region 3! of the furnace units ID by suitable conveyor rolls including, for example, a pair of pinch rolls 38 disposed adjacent the entrance opening of the first furnace unit. The pinch rolls 38 may be driven in any suitable manner for positively feeding each work piece I I over the set of end grooves 24 in the rollers 23 which are in alignment with the pinch rolls 38.

Since the pinch rolls 38 are usually driven at a speed which is considerably faster, than the rollers 23, the work pieces I I positively fed into the furnace units ID by the pinch rolls 38, will frictionally slide over the set of end grooves 24 in the rollers 23 until each work piece leaves the pinch rolls. When this occurs, the rollers 23 then become effective to transport and advance each work piece I I initially moved into the end grooves 24 thereof.

The heated work pieces II are discharged lengthwise in rapid succession and leave the rollers 23 at a second region, indicated at 39 in Fig. 1, which is laterally removed from the first region 31 at which the incoming work pieces are received. At the second region 39 each work piece II is advanced lengthwise in the opposite set of end grooves 24 of the rollers 23. When each work piece I I at the second region 39 is advanced sufficiently for the forward end thereof to be gripped by suitable conveyor rolls including, for example, a pair of pinch rolls'40 adjacent the exit end of the final furnace unit III, such pinch rolls will be effective to withdraw the work pieces rapidly from the furnace units Ill. The pinch rolls 4D become effective to transport the work pieces I'I about to be discharged from th furnace units It because such pinch rolls are driven at a higher speed than the rollers 23 and substantially at the same speed as the pinch rolls 38.

While the work pieces II are being advanced as a battery through the furnace units I by the rollers 23, the work pieces are bodily shifted sideways in a number of steps from the incoming first region 31. In the embodiment illustrated this is accomplished by providing suitable work transfer mechanisms M in the aps between adjacent ends of furnace units I0. As best shown in Figs. 3 to 6 inclusive, each work transfer mechanism 4| comprises a cradle 42 having teeth 43 at the top edge thereof of substantially the sam size as the grooves 24 in the rollers 23. The cradle 42 in each gap between adjacent ends of furnace units I0 is positioned closely adjacent to and at oneside of a conveyor roller 23.

The cradles 42 at the bottom parts thereof are formed with spaced apart side walls 44 which are substantially parallel and extend downwardly from the top toothed portions 43, as shown in Fig. 3. As seen in Figs. 4 to 6 inclusive, the side walls 44 are formed with aligned notches to provide three spaced apart legs 45, 46 and 41.

In the spaces between the spaced apart side walls 44 of each cradle 42 are positioned a pair of disks 48 and 49 of substantial thickness. The disks 48 and 49 are fixed to shafts 50 and respectively. As best shown in Figs. 3 and 4, each shaft 59 is journaled at its ends in bearings 52 which may be removably secured to theopposing ends of adjacent furnace units III. The shafts 50 may be driven in any suitable manner and, as shown, are driven from the shafts 33 through gearing indicated at 53 and 54. The shafts 5| may be journaled at their ends in the same manner as as the shafts 50 and chain driven therefrom, as indicated at 55.

To the disks 48 and 49, adjacent to the peripheral edges thereof, are fixed pins 56 and 51, respectively. As shown in Figs. 4 and 6, the distances between the shafts 5B and 5| and the pins 55 and 51, respectively, are substantially the same as the distances between the legs 45 and 46 and the legs 46a'nd '41 of the cradle 42. The pins 56 and 5'! project outwardly from the opposing faces of the disks 48 and 49 and engage and bear against the closed ends of the notches formed in the spaced apart side walls 44; The operation of the work transfer mechanisms 4I- just. described is as follows, it being under-' stood that the several transfer mechanisms are adjusted so that they all operate in unison to shift the work pieces I] laterally in a number of steps from the region 37 to the region 39 in the furnace units III. In Fig. 4 the cradle 42 is in a first intermediate position at which time the cradle is supported at the closed ends of the notches'by both the pins 56 and 51 and also the shafts 50 and 5|. In such first intermediate position of the cradle 42, the teeth 43 at the top edge thereof are below the grooves 24 in the roller 23 adjacent thereto and cannot interfere with the lengthwise movement of the work pieces II in the furnace-units III.

The disks 48 and 49 as seen in Fig. 4 rotate about the shafts 50 and SI in a clockwise direction. When the disks 48 and 49 rotate from the position shown in Fig. 4 to that shown in Fig. 5, the cradle is raised by the pins 56 and 5'! from its first intermediate position to its raised position. In moving to the raised position shown in Fig. 5, the teeth 43 at the top edge of the cradle 42 are moved upwardly to a height or level above the rollers 23 adjacent thereto. As the teeth 43 at the top edges of the several cradles 42 move up in unison, therefore, the work pieces in the grooves 24 of the rollers 23 are picked up by the teeth 43 and lifted off the rollers.

When the disks 48 and 49 rotate 90 from the raised position shown in Fig. 5 to a second intermediate position shown in Fig. 6, the work pieces II are shifted laterally of the furnace units I0 from one set of aligned grooves in the rollers 23 to an adjacent set of aligned grooves therein. In moving to the second intermediate position shown in Fig. 6, the teeth 43 pass below the grooves 24 in the rollers 23, so that the work pieces I I are again supported by the rollers and advanced lengthwise by the latter through the furnace units It.

From the second intermediate position shown in Fig. 6 the disks 48 and 49 continue to rotate in a clockwise direction. After rotating from thesecond intermediate position in Fig. 6, the disks 48 and 49 return to the first intermediate position shown in Fig. 4 after passing through a lower position which has not been illustrated. From such first intermediate position of the disks 48 and 49; the operation of the work transfer mechanism is repeated in the manner just described, whereby the work pieces II are bodily shifted in a number of steps from one set of aligned grooves 24 to an adjacent set of aligned grooves in the rollers 23.

In view of the foregoing, it will now be understood that an improved heating furnace has been provided in which elongated work pieces can be rapidly fed lengthwise to and rapidly removed lengthwise from the heating furnace while the work pieces in the heating furnace can be transported lengthwise at a considerably slower speed. In the embodiment of the invention shown and just described, five furnace units it are provided in end to end relation, as seen in Fig. 1. The elongated work pieces I I are of such length that, when the work pieces are fed in succession into the furnace units III at the incoming region 31, each work piece extends from the entrance opening of the first furnace unit Ill approximately to the exit end of the fourth furnace unit Ill. Thus, in the length of time each work piece I I is in the heating furnace shown, it is advanced lengthwise therethrough a distance approximately equal 'tothe length of one furnace unit III plus.

th see distan bet een the f urt an iine fu n e u t 10, bef re he fo war e d thereo ea hes a osi on whe it will be ri ed by the pi h ol e s 4n.

.n v ncin th gh the he tin furnaee, c o k ece is bodil hifted in five steps f o the nd r ov s 2 the rollers .23 at the region 3 o e opposite end roo s 4 at the re on D in the in va s 9f ime in which he wo a sf m chan sm 4! shi s he wor pieces I I d ay om ne se of a i ned ooves 24 to on a ac se o aligned roo es n t e er 3, e o k p eces momentari y are not moved lengthwise through the heating furnace. However, as soon as the shifting and transferring of he work p e H is com leted b th work n e m a ism, t e onve or olle s be co e ive to a n e and trans ort-the ork pi c s l thw se from the in et to the out t of th he t lui' e T us, w ile t e w rk i s I are moved leng i e more or less continuu v n e e pro s to the heatin fu nace and le ve h e ing nac in h same nor, the forward advance of the Work pieces he a n n e s in ermi ent a act r- By a of am and w thout limi ati n, t e elongated work pieces I I may be fed single line tr n t to the heatingfui'n oe a d eav th h a ing furnace in a similar manner at a speed of bou 300 ee e minute wh le the o p e may advan e engthwi e in he u hee at an e e t spee of out t pe minute to c mp sh the s ed hea treating o he work. It will readily be apparent that if a heating furnace were provided to accomplish the identical heat treatment of the work in whichthe Work pieces pass in single line transit at a speed of b u 0 feet r mi u a h at ng furnace o undu y long l t ld e necessa It should be noted that each work piece II will pass through the heating furnace shown in approximately the same interval of time so that successive longitudinal portions of each work piece will be heated substantially to the same .eleivetted mper t re- Thus dur ng the movemen o the work p ce ll t rou h he furnace units I 1;, different longitudinal portions of the work p eces wil be u e d t the high t m erature ea i f e ts n e u -hos cham ers I2 for app o im te e s me o e all leng h o t me; a d w so be as g h ugh the gaps between the ends of adjacent furnace units II] for approx.- imately the same overall length of time. While the o k s pass n h gh the a s betwe n th ends of adjacent furnace units II], the portions thereof he a s a e en eloped by atmosp e s of h d furnac ases di char ed from h t ance nd ex p i gs 4 a d I5, as p evio s y p a ned t eby p ec i g t e wo k a d p ev n u i ab e coo i a d oxid t onsuiteble sp chan e m chani m, (not s n o a y well known ype m y be p ovided for the driving means for the disks 48 and .49, whereby the latter will be rotated at the desired speed to shift the work pieces I I sideways on theconveyor rollers 23. Further, by providing such speed ha me ha sm ch i ope ble to d s h nect the disks 48 and 49 from the driving means therefor. t e di ks may e s op d at os t on at which the cradles 42 will be below the conveyor rollers 23 and not interfere with the transport of the work pieces II by the latter. In this maner all o e w r p e s an e move ou o the furnace units I!) when this becomes necessary. If desired, provision may begmade for re- VtISih the rotation of the shafts 33 whereby the work pieces can be moved backward as a group hen the work ransfer me ha isms 4| are r nderc inoperable and it should become necessary to move all of the work pieces out of the heating furnace. The parts of the work transfer mechanism H adjacent the exit openin s I5, and in the path of movement of the heated furnace gases discharged therefrom, may be formed of any Well known high temperature alloy.

The heating furnace illustrated is extremely flexible and may be employed for heating work pieces of different sizes. Thus, when work pieces which are of less weight per unit length are heat treated in the heating furnace shown and the work pieces may pass through the heating fur nace in a shorter length of time, the pinch rollers 55 at the exit opening of the final furnace unit Ill can be shifted so that the work pieces will be gripped by such pinch rollers after the work has been shifted sideways a number of steps less than the maximum number of steps provided for the heating furnace.

In heat treating metallic work, such as steel,

copper, brass and the like, for example, the number of furnace units III required in each particular case will depend, of course, upon the weight per unit length of the Work and the composition of the work as well as the elevated temperature to which the work must be heated to impart thereto the desired metallurgical characteristics. Further, the number of furnace units I0 necessary and the number of steps in which the work pieces are bodily moved sideways from the incoming region 3'! to the outgoing region 39 will depend upon additional factors, such as, for example, the speed at which the work pieces are fed in single line transit to the heating furnace and conveyed therefrom in a similar manner.

Although I have shown and described a particular embodiment of the invention, it will be apparent to those skilled in the art that modifications and changes may be made without departing from the spirit and scope of the invention.

I therefore aim to cover all modifications and changes which come within the spirit and scope of the invention, as pointed out in the following claims.

What is claimed is:

l. A heating apparatus comprising a number of axially aligned separate units in end to end relation and'having entrancevand exit openings for passage of a number of work pieces therethrough alongside of each other, conveyor mechanism iin the space between said units for supporting and transporting the work pieces through the units, on pa o sa d con yo mech ism being a ranged to receive incoming work pieces and anhe pe t thereo la ra ly o se it respect t aid one part being an e to di ar e h ated work pieces, and transfer mechanism for shifting he o k i es latera y n sa d c e m ch during transport through and between said units to move the work pieces from said one part to said other part of the conveyor mechanism.

2, A heating apparatus comprising a number of units in end to end relation and having entrance and exit openings for passage of a number of work pieces of elongated extent therethrough alongside of each other, conveyor mechanism ineluding rolls between the units for supporting and transporting work pieces through the units, and including work transfer mechanisms between the units for bodily shifting the work 9 pieces sideways during transport through the units.

3. Heating apparatus comprising a number of furnace units in end to end relation and having entrance and exit openings for passage therethrough of a number of elongated articles of greater length than each furance unit, conveyor mechanism including hollow rolls between the furnace units for supporting and transporting the elongated articles through the furnace units, said hollow rolls having inlets and outlets for circulating a coolant therethrough, and means comprising work transfer mechanisms including parts disposed between the furnace units adjacent to the hollow rolls for bodily shifting the elongated articles sideways during transport through the furnace units.

4. Heating apparatus comprising a number of furnace units in end to end relation and having entrance and exit openings for passage therethrough of elongated articles of greater length than each furnace unit, means for firing said furnace units to an elevated temperature, conveyor mechanism including multi-grooved rolls between the furnace units for supporting and transporting the elongated articles through the furnace units, and means including article transfer mechanisms for raising and bodily shifting the elongated articles from one set of aligned grooves to another set of aligned grooves in the rolls during transport through the furnace units.

5. Heating apparatus comprising a number of furnace units in end to end relation and having entrance and exit openings for passage therethrough of elongated articles of greater length than each furnace unit, means for firing said furnace units to an elevated temperature, conveyor mechanism including .multi-grooved rolls between the furnace units for supporting and transporting the elongated articles through the furnace units, and article transfer means including movable toothed elements between the furnace units operable to intermittently interfere with the transport of the elongated articles by said rolls and to shift the articles from one set of aligned grooves to another set of aligned grooves in said rolls.

6. Heating apparatus comprising a number of furnace units in end to end relation and having entrance and exit openings for passage therethrough of elongated articles of greater length than each furnace unit, conveyor mechanism including multi-grooved rolls between the furnace units for supporting and transporting the elongated articles through the furnace units, means for feeding the elongated articles lengthwise in succession to a first set of aligned grooves in said rolls, means for removing the elongated articles lengthwise in succession from a second set of aligned grooves in said rolls, and article transfer mechanism operable intermittently to interfere with the transport of the elongated articles by said rolls and shift the articles in one or more steps from said first set of aligned grooves to said second set of aligned grooves during transport of the articles through the furnace units.

'7. A heating apparatus comprising a number of units in end to end relation and having entrance and exit openings for passage therethrough of elongated articles of greater length than each unit, means for firing each unit to an elevated temperature, conveyor mechanism including rolls between the units for supporting and transporting the elongated articles through the units, means for feeding the elongated articles lengthwise in succession onto one region of said rolls, means for discharging the elongated articles lengthwise in succession from a second region of the rolls, and means for bodily shifting the elongated articles sideways on said rolls from said first region to said second region during lengthwise transport through said units.

8. Heating apparatus comprising a number of furnace units in end to end relation and having entrance and exit openings for passage therethrough of elongated articles of greater length than each furnace unit, means for firing each furnace unit to an elevated temperature, conveyor mechanism including rolls between the furnace units for supporting and transporting the elongated articles through the furnace units, means including pinch rolls adjacent to the entrance opening of the initial heating furnace unit for feeding articles lengthwise in succession onto a first region of said rolls, means including pinch rolls adjacent to the exit opening of the final furnace unit for discharging the elongated articles lengthwise in succession from a second region of the rolls, and means for bodily shifting the elongated articles sideways on said rolls from said first region to said second region during lengthwise transport through said furnace units.

FREDERIC O. HESS.

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

UNITED STATES PATENTS Number Name Date 699,130 Allis May 6, 1902 704,286 Allis July 8, 1902 720,904 Edwards Feb. 1'7, 1903 863,841 George Aug. 20, 1907 2,326,843 Ely Aug. 17, 1943 2,451,053 Anderson et al. Oct. 12, 1948

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