US1776823A - Heating apparatus - Google Patents

Description

Dv L. SUMMEY HEATING APPARATUS Sept. 30, 1930.

Filed May 3l 1923 Sept. 30, 1930, DA L SUMMEY 1,776,823

HEATING APPARATUS Filed Kay 5l, 1923 7 SheQTs-Shee 2 gvwentoz Sept. 30, 1930. D, SUMMEY lI'I'ING' APPARATUS Filed lay 5l, 1923 7 Sheets-Sheet gpt. 30, 1930. o. L. sUMMl-:Y 1,776,823

' HEATING APPARATUS Sept 30, 1930- D. l. suMMEY HEATING APPARATUS Filed lay 3l, 1923 vwanboz 7 Sheets-Sheet Sept. .30, 1930.l D. l... sUMMEY 1,7761823 HEATING APPARATUS Filed Kay 51, 1923 7 Sheets-Sheet 6 n'oenboz @51j da @Hom 4 m@ @i5/e@ Sept 30, 1930. D L SUMMEY 1,776,823

HEATING APPARATUS Filed May A51, 1923 7` Sheets-Sheet 7 mnuuumm ffy/f.'

Patented Sept. 30, 1930 PATENT OFFICE DAVID Sm, 6l' WATERBUBY, CONNECTICUT HEATING APPARATUS Application med Kay $1, 1988. Serial No. 642,411.

This invention relates to heating appara- `nections and arrangements of the hair pin tus and more particularly to annealing furnaces.

It is one of the principal objects of the in vention to provide an eicient electric heating furnace that is economical as to the consumption of electric current for heating' the furnace and the material placed therein.

It is a further object of theinvention to provide a heating apparatus capable of a l,large output, that requires a mlnimum of manual labor.

It is still a further object of the invention to provide an eicient heating apparatus utilizing electric resistance heating elements in which the heating elements may be removed and replaced without any material tearing down of the furnace.

With these general objects'in view, the invention consists in the .features, combinations, details of construction and arrangement of parts which will first be described in connection with the accom anying drawings and then more particularly pointed out.

In the drawingsl 1 Fig. 1 is a view, partly in longitudinal section and partly diagrammatic of a heating apparatus constructed in accordance with the invention; 1

Fig. 2 is a vertical transverse sectional view through the heating chamber; l Fig. 3 is an enlarged cross-sectional view taken on the line 3-3 of Fig. 2; f Fig. 4 is a plan view of a resistance wire removed, with part broken away;

Fig.. 5 is a similar view of a modied form of resistance wire; v

Fig. 6 is a detail view showing part of a conveyor chain in plan;` f

Fig. 7 is a'detail view Showing part of a conveyorv and its pulley in side elevation; Fig. 8 is a longitudinal vertical sectional view of the heating chamber; l Fig. 9 is a view of the same in side elevation; y n i Fig. 10 is a schematic view showing the-alternate arrangements of the wire connections; l i j Fig. 11 i a plan view of a hair pin form of wire;

' tion portion ofthe wire. It Will be under- Fig. 12 is a schematic view showing' the con# wires;

Fig. 13 is a view, partly in vertical transverse section and partly diagrammatic of a modified form of apparatus in which the coils are heated inductively;

Fi 14 isa view of the samepartly in longitu inal vertical section;

Figs. 15 and 16 are views in vertical section and plan of a coil of material and a binder;

Fig. 17 is a diagrammatic'view showing a pyrometer control; and

Fig. 18 is a wiring diagram for the same.

Referring to the drawings, the apparatus illustrated as an example in Figs. 1-10 cornprising along furnace chamber'lO enclosed by a housing 11 of brick and fire brick or other suitable material.

There is provided heat supplying means,l such, for example, as -electric resistance elements, and in structures embodying the invention to the best advantage these elements are arranged to supply heating zones of varying degree. Although capable. of various constructions, in the embodiment illustrated, supported and distributed as hereinafter descri ed, are a plurality of long, straight nickel-chromium wires 12 running lengthwise of the furnace and extending almost the entire length of the enclosed chamber 10. In order to provide zones of varying degrees'of heat', for a purpose later referred to, the individualwires 12 have a varying cross-section. Y In the particular embodiment illustrated each wire is formed with, a small or high resistance 'cross-section at its central portion and a large or low resistance crosssection at its ends. With this construction the heating effect of the wires'at the ends of the chamber. is substantially immaterial and at the central part of the chamber it is relatively high, the length of the hot zone being determined by the' length of the small cross-sec-4 stoodthat the extent of the various cross-- sections may be varied as desired and that while the wires shown are all alike as to crosssectional arrangement, the various wires may differ in this respect. Further, by stepping l.

` 55 ltrates the circuit scheme for the wires and down the cross-section, the heating eti-'ect can f be gradually increased and decreased. Such various constructions, in the embodiment il-l lustrated, set at spaced intervals along vthe chamber 10, are a pluralityof transverse supkportiiig frames 14, which are seated in the chamber walls. These frames are of skeleton construction and carried thereby are perfo- 'rate blocks 16 of insulating material, sucli as tile. The perforations of the similarly' located blocks of the several frames are lined up lengthwise of the chamber so that the resistance wires 12 may be threaded through them ina straight line. The frames themselves are made of a material capable of withstanding -continued high .temperatures without structural deformation and without oxidizing. For this purpose, nickel-chromium andv similar alloys have been found suitable. That is, the frames may be made of a metal having substantially the Isame heat resisting characteristics as the metal of the wires. p

The wires 12 terminate just beyond the final frame at each end of the chamber andthe ends are connected in circuit. To neutralize the fields created by the current in wires 12, thus avoiding inductive eiects, in the embodiment shown, alternate wires are connected at one end, to one bus bar and the other wires are connected to a second bus bar, the direction side the latter.

of flow being lreversed in the two sets.A As shown in Figs. 2 and 3 the ends of one set of wires are connected by detachable clamps 17 with bus bars 18 carried by the housing walls and running around the four sides thereof. The ends of the alternate wires are connected by detachable clamps 17 with bus bars 181 similar to bus bars 18 and yarranged alongdiagrammatically onlypin Fig. 2, the full constructions being shown in Fig. 3. The bus 'bars 18 and 181are connected to main leads 13, 15V and 131, 151, in such manner that the v plus ends of the wires of one set are at the same end of thel furnace as the minus ends of the wires of the other set.' Fig. 10 illusbus bars.

While round wires and round holes in the insulators have been shown, it is to be understood that other cross-sectional shapes may be used such, for example, as ribbon or triangular s apes.

There is provided conveyor means for moving the material to be heated through the furnace chamber, In structures embodying The clamps 17 are shown1 the invention to the best advantage the conveyor ,means comprises an endless chain, and where the type o material permits, the conveyor is arranged to carry material on bothA strands. While capable of various constructions, in that hereyshown'as an example, which isy partcularly""adapted for heating large coils of metal, such, for example, as brass,

Vthe chain is made up of flat, skeleton links 25 which are functionally reversible. That is,

coils may be carried on either face of the chain. Each link has, at one side, two double lugs 26 and at the other side, two single lugs 27. The links being assembled, they are con- 'links and pins in the present embodiment, are

made of nickel chromium alloy. The pulleys and shafts being in the relatively cool zones may be made of ordinary steel.

While one conveyor chain only may be used, in the embodiment illustrated four chains are provided, arranged in nested relation. That is, there are two bottom chains side by side, and two top chains above them. The several conveyor elements are duplications in the present constructions. With' lfour conveyor elements in nested relation, a large conveyor capacity is obtained with a relatively small housing and there -is marked economy in heating, as the loss of heat by radiation per unit conveyor is relatively small.

In order to provide eiective` and economical heating, provision is 'made whereby each strand of each conveyor is surroundedy by resistance elements. To this end, as here shown as an example, the'supporting frames 14: have central legs 19 and three cross bars 20, skeleton in form and carrying perforate insulating blocks 16. Through these blocks are threaded additional resistance wires 12 like those already described. As appears in Fig. 2, the wires supported by the cross bars of the frames are alternately connected by clamps 17 with crossbus bar extensions 21 and 211, connected respectively with the bus bars 18 and 181. The wires supported by the vertical legs of the frames are similarly connected with vertical bus bar extensions 22 and 221 also connected to bus bars 18 and 181.

With the construction described, the connections to the bus bars, the bus bars themselves and the take out leads to the supply circuit are alll located in the relatively cool zones of the furnace and loss of heat through While the Wires are shown as all connected in a single supply circuit, it will be understood that they may be grouped for a number vof transformers, which also makes pos- 5 sible a heat control by voltage regulation.

The cross bars 20 of the frames 14 also serve as support for rails or angle pieces 29 which serve as tracks Kon which the conveyor chains run and which are suitably vmade of the same metal as the chains, e. g.Y nickelchromium alloy. u

If desired, the frames 14 may be grouped -in tvvo sets, alternate frames serving only to support the'rails 29, the other frames serv- 15 ing only to carry the insulating blocks 16.

That is, in the construction referred to, the frames which support the chains do not support the Wires and the Wire supporting frames do not support .the rails, and chains.

l20 With such a construction, vibration of the insulating blocks is avoided and there is little or no danger of current leakages.

With the construction above described, coils of material to be heated, indicated at 34, being loaded and unloaded as later described, are carried in one direction on the top strandl of each chain and in the opposite direction on the bottom strand `of each chain. Thus there are eight rows of conveyed material moving through the furnace chamber, four in one direction and four in the opposite direction. As appears more clearly in'- F ig.- 2, each row of moving material, i. e., each strand of each chain, is surrounded bv resistance heating Wires. Considering any one conveyor as an example, asthe coils on the top strand leave the central hot zone of Lthe furnace chamber, they meet the oppositely moving cold coils on the bottom strand in the relatively cool end zone, The heat given off from the hot coils gives the cold coils a preheating and thus an economy in heat supply is effected. The same preheating takes place at the other end of the furnace chamber, the incoming cold coils on the top strand being preheated by the outgoing hot coils on the bottom strand.

Electricity as a heating medium gives the advantage, among others, of an accurate and uniform heating effect and, due to the construction described, high furnace efficiency is made possiblel and the furnace is consequently economical as to the heating medium, even With electricity. Both strands ofthe conveyor'chains move through the heating zone and the temperature of the chains al- Ways remains much higher than atmosphere.

z With a double duty chain the dead load is reduced to a minimum, heat is economized and the investment cost of material is substantially reduced.

Should any resistance element break dovvn,`

its removal and replacement can be accomplished without taking down the furnace or 65 substantial portions thereof. A .Workman can enter the relatively cool end of the furnace through doors hereinafter described, detach the clamp 17 of the Wire in question and draw out the Wire. rl`he Wire may be removed from the chamber through a normally closed hole in the end wall of the housing, for example, a hole provided by the removal 'of one ormore of the bricks that make up the Wall" In thesame manner a new or rclpaired Wire can be threaded through the supports and connected up in circuit. In

this connection it is noted that the Walls of the furnace form merely a housing, the heating elements being supported independently of the housing Walls. A further advantage of the constructiondescribed is that it makes possible the use of standard sizes of insulating blocks instead of, numerous special sizes.

There is provided means for removing the material to be heated, such as coils, from the conveyor and meansfor feeding material to as the latteris advanced by the conveyor.

The rod 44 isconnected to a piston 45 Working in a cylinder 46. Opening into opposite ends of the `cylinder 46 are pipes 47, 48,

connected by a 4-Way valve 49 vwith an exhaust pipe 50 and a supply pipe 51. Pipe 51 H leads to any suitable source of fluid pressure, such as compressed air, not shovvn.

When the hooked rod .44 receives a coil (as appears in Fig. 1) the valve 49 is operated, by means hereinafter described, to admit air through pipe 47, thus causing piston 45 to Withdraw the rod 44, the cylinder exhausting through pipe 48, valve 49and pipe 50. By this operation, the coil is drawn out of the furnace chamber across platform 42 onto the conveyor 43, which carries it away. When valve 49 is reversed, as later described. the piston has a reverse movement and the rod 44 is replaced in position in the chamber to receive the next coil.

The'discharge conveyor 43 is shown diagrammatically as a short Aendless belt or chain. It will be understood that it may be extended to carry the discharged coil to any point desired. nstead of a discharge conveyor, there may be used Van elevator or the like to carry the removed coil to a quenc ing it. p At' the opposite end of the furnace is an opening 53 having a platform 54 like platform 42. Coils are brought up to the platform 54 by a 'conveyor 55 like conveyor 43. The coils are pushed across platform 54 onto the conveyor chain by a push rod 56 havin 5 a curved end to embrace a coil. The pus ,-rod y56 is connected with the piston'of aluid pressure unit 57 that is like the unit just described. By the operation of the valve of this unit 57, the rod 56 is caused to push a coil onto the conveyor chain in the furnace and is withdrawn for the next loading operi ation.

Doors are provided for openings 40 and 53 and there is provided means for operating these doors. Although capable of various constructions, in the present embodiment, the opening 40 is normally closed by a sliding door 41, notched or slotted to accommodate the platform 42 and the rod 44. This door is operated by a lever 59 connected by a link 60 with the piston rod 61 of a fluid pressure unit 62, like the units above described. lBy operation of the valve of iuid pressure unit 62, the door 41 is lcaused to o en and close.

5 A similar door 63 closes opening 53 and is operated by lever 64 and fluid 'pressure unit 65 that are duplicates of the similar elements associated with door 41. f I

.There is provided means for operating the y several valves of the fluid pressure uni-ts above referred to and in constructions embodying the invention to the best advantagel this operation is automatic and is controlled by the movement of either the conveyor chain 3 or the coils carried thereby. Although capable of various constructions, in that here' shown as an example, in line with the conveyor chain at the discharge end, is a contact plunger 68 slidable in the end wall of the furnace and normally held by a spring 69 in a position to be engaged by a coil as the latter moves into the embrace of the hooked rod 44. The other end of plunger 68 carries the contact member of a relay 70. This a coil of material is moved into contact with plunger 68, relay 70 is closed'and through Y the connections describedthe fluid pressure' units are operated toopen the door and'withdraw the discharge rod, thus removing the coil as above described.- Y

In the presentembodiment the feeding 0peration is controlled by the chain movement, so that the coils will be fedin properly spaced relay located in a shunt across a main line .nected by lever 76 with the valve of Huid pressure `unit 62 that operates door 41. When relation tothe conveyor chain. To this end, as here shown as an example, on the shaft 32, which drives the chain pulley, is a ratchet wheel 80 having a luralit of notches'81. Riding on the perip ery o the Wheel 80 is a pivotally mounted detent 82, which drops into the notches 81 as the wheel rotates. The notches are so spaced that one is presented to the detent each time it is desired to feed a coil. The detent carries an arm 83 on which is mounted the contact-member of a relay 84 located in a shunt across the main line wire 71, and in which is connected one Winding of a reversely Wound solenoid 85. The core of this solenoid is connected by lever 86 with the valve of fluid pressure unit 57. In parallel With the shunt just described is a loop including one Winding of a reversely wound solenoid 87 the core of which is connected by lever 88 with the valve of fluid pressure unit 65. When the detent 82 drops into a notch 81, the relay 84 is closed. Solenoids 85, 87 being thus actuatedoperate the valves of fluid pressure units 57, 65, to cause door 63 to be opened and pusher 56 to push a coil onto the conveyor chain.

Provision is made for automatically causing the return movements of the rods 44, 56 vand the doors 41, 63.y To this end, as here shown as an example, carried by the hooked rod 44 is a trip arm 90 positioned to tri a spring pressed lever 91 as the rod 44 reac es the end of the discharge stroke. This lever 91 is connected with the contact member of a relay 92 located in a shunt across-the main line wire 71, and in which is connected the second or reverse Winding of solenoid 73. v

In parallel with this shunt is a loop including the second or reverse Winding of solenold 75. When trip arm 90 causes the closing of relay 92 the cores of the two' solenoids are reversed, thus reversing the valves of the two fluid pressure units and the rod 44 is returned to normal position and the door 41 is closed.

The piston of fluid pressure unit 52 has a back extension 93 carrying a trip arm 94 located to trip a spring pressed lever 95 as the pusher rod 56 reaches the end of its feeding stroke. This lever 95 is connected With the contact member of a relay 96 in a shunt across the main line wire 71, and in which is connected the second or reverse winding of solenoid 85. In parallel with this shuntis a loop including the second or reverse Winding of solenoid 87 When the relay 96 is closed, the cores of solenoids 85, 87 are reversed, thus reversing the valves of fluid pressure units 57, 65 and the rod 56 is withdrawn and door 63 is closed.

In the above description of the loading, unloading and control features, reference has been made to the top strand of the right hand,

top conveyor chain of Fig. 2. For the lower `strand of this chain, the loading and unloadythe coils are lbrought 'up b ing ends are reversed.y Below. the discharge opening 40 for thetocpmstrand, lin the presentv embodiment, is a fee g opening 97 for the bottom strand, this bein a-continuation of opening 40.' Loading o coils is carried on bymeans of apparatus that is a' duplication of the loadinnr means described, except that a' conveyor 255 that is located at right ang es to the furnace instead of alongside, as in the case of conveyor 55. Figs. 8 and 9 indicate a push-rod slidable in a thimble 108 located in the side 256 that is a counterpart ofpush rod 56.

At the other end of the furnace, below feeding opening 53 is a discharge opening 98 for the bottom strand, this bein shown as a continuation of opening'53. nloading of coils is carried on by means of apparatus that is a duplication of the unloading means described except that the coils are carried oil by a conveyor 243'that is atright angles to the furnace instead ofalongside as in the case of conveyor 43. Figs. 8 and 9'indicate a hooked rod 244 that is a counterpart of hooked rod 44 exce t that-,it faces the opposite way in view of t e reverse direction of the conveyed coils.

For the lower conveyor chains, the above described pairs of loading and unloading units are duplicated.

Figs. 8 and 9 indicate the push rod 356 and the discharge rod 344 of the top strand and the push rod 456 and discharge rod 444 of the bottom strand. These iigures alsoshow the conveyors 355, 343 and 443 and 455 for the top and bottom strands, of this lower chain. It will be 'seen that there are on one side of the furnace four loading and four unloading units. These units are duplicated on the other side of the furnace forl the other two conveyor chains and no further reference thereto is necessa o In Figs. 13 an 14 there is illustrated a` modification in which the coils of material are heated inductively.l In the exempliiication shown, there is provided along housing 101 similar to the housing already described lexcept that it is of one-conveyor size. Moving in the chamber ,102 formed by this housing is a conveyor -cha-in 103 for carrying coils, this chain being like the/conveyor chains already described, and running on suitably supported rails or angle pieces 104. It is i Ldriven by a shaft 105 which .rotates the pulley 106. Coils of material lare loaded onto thel top strand and unloaded from the bottom strand at the end of the chamber 102 shown at the left in Fig. 14 by apparatus and in the coil 100 wound around the central leg of the core, the primary coil being connected with an .suitable source, not shown.

here is provided means for causing relaltive movement between a coil of material and ment the transformer velements (except a .part of the core later referred to) are stationar and the coil of material is moved. To this end, as here ,shown as an example,

wall of housing 101, opposite the heating chamber 107, is a ram or pusher 109. Thisl pusher is connected 'to the piston of a fluid pressure unit 110 like the fluid pressure units` described,the valve being operated as hereinafter described.

` The pusher 109 is .positioned to transfer4 i il the heating chamber 107. This table is mounted on a rod or plunger 112 connected to the ypiston of a fluid pressure unit 113 like unit 110, the valve being operated as hereinafter described. At the time of transfer of the coil from the conveyor chain, the table 111 is in theldotted line position indicated at 111 in Fig. 13. After receiving a coil the table is elevated to a osition 'ust beyond the full line position'of ig. 13. n this position,

the table'111 makes contact with the legs 9,9

of the core and becomes the fourth leg of the core, and the coil of material is between the rima coil and thelegs of the core.

uitab e current being supplled tothe primary 100, the coil of material acts as a secondary and the metal is heated by the induced currents set up therein. The primary coil and the core may be protected by suitable insulation from the heat generated in the coil of material and may be air cooled if desired.

After the coil is heated, the table 111 is lowered by means of its fluid pressure unit to the dotted line osition'111" of Fig. 13, in which position t e coil is in line with the bottom strand of the conveyor chainif- From the table, the coil of material is transferred onto the conveyor by a pusher or ram .114

like the pusher 109. This pusher 114 is connected to the iston of a fluid pressure unit 115 like the unit 110, the valve being operated as hereinafter described. .Pusher 114 is then withdrawn, and pusher 109 having been withdrawn meanwhile, the table 111y is returned to position 111 ready to receive the next coil of material.

lcs.

Whilethe valves of the fluid ressure units I vision is made for an automatic control. 'In

the exemplication here shown, the valve of unit 110 is connected by a lever 117 with the.

core of a reversely wound solenoid 118. One' winding ofthis solenoid is connected in a shunt, which includes a relay 119, across a main line 171, connected with a suitable source not shown. The contact member of relay 119 is carried on the end of a spring pressed plunger 120, similar to plunger 68, and slidable inthe end wall of t e housing 101. When a coil of material reaches properposition to be transferred to table 111, it actuates the plunger 120 and closes'rela 119.- Thus solenoid 118 operates the valvel o iiid pressure unit 110 to cause pusher 109 to 'move the coil onto table 111.

To lreverse the valve in order to cause return of pusher 109, the piston of unit 110 has, as here shown, a rearextension 121 carr ing a trip arm 122 positioned to trip, as t, e piston reaches the end of its transfer or pushing stroke, a spring pressed lever 123. This lever is connected with a contact member of a rela 124 located in a shunt across the main line 1 1 and in which is connected the second winding of solenoid 118. When relay 124 is closed the valve of fluid pressure unit 110 is reversed and pusher 109 is withdrawn. At this period in the cycle of operations, luid pressure'unit 113 is tending to elevate table 111, but the parts are held against such movement 'until the table receives a coil of material.v To this end, as here shown as an example, an arm 128. on a rear extension 129 carried by the piston of unit 113 is arranged to be engaged by a sliding stop 127, to hold the table in position 11la. To release this stop, on the extension 121 of unit 110, is a trip arm 151 positioned and arranged to trip momentarily a spring-pressed lever 152, after the piston of unit 110 has withdrawn the pusher 109 from the path of the table and nearly reached the end of its back stroke. This lever carries the contact `element of a relay 153 located in shunt across the main line 171 andin which is connected one winding of a reversely wound solenoid y125. The core of this solenoid is connected by a lever 126 with sliding stop 127. When relay 153 is closed, therefore, the stop 127 is withdrawn and unit 113 is free to complete the elevation of table 111 to coil heating position. It will Provision is made for lowering the table l vbe apparent that, following this operation of solenoid 125 and stop 127 by the momentary closing of relay 153', the solenoid and sto retain their position by the inertia of the parts until again moved as later described.

a given time interval. To thls end, as here shown as, an example, mounted on shaft 105 is a wheel 130 having a plurality of spaced notches 131. Riding on the periphery of wheel130 is a spring-pressed pivoted detent 132, which vcarries the contact member of a relay 134. This relay is located in a shunt across` the/main line 171, in which shunt is connected one winding of a reversely wound solenoid 135, the core of which is connected by umass' a lever 136 with the valve of iluid'pressure unit 113. When the detent 132 drops into a notch 131, relay 134 is closed and through solenoid 135 the valve of unit 113 is operated to cause the table 111 to be lowered to position 111". The heated coil is now positioned to be transferred back to the conveyor chain but onto the'other strand. To effect operation of pusher 114, as here shown, on the extension 129 of table unit 113is a trip arm 137 located and arranged to tripl momentarily a spring pressed lever 138 as t e piston of unit 113 reaches or nearly reaches the end of its withdrawal stroke. This lever carries the contact element of a relay 139 that is located in a shunt across the main line 171, in which shunt is connected one winding of a reversely wound solenoid 140. vThe core of this solenoid is connected by a lever 141 with the valve of'iiuid pressurey unit 115. When relay 139 is closed, the valve of unit 115 is operated to cause pusher 114 to transfer the heated coil from the table 111 to the bottom strand of the conveyor chain. As in the case of the momenta trip above described, the parts are held 1n moved position, following the momentary energizing of solenoidY 140,'by inertia. l

` To reverse the valve of unit 115, thereby to cause return of pusher I114, as here shown as an example, the piston of unit 115 carries a rea-r extension 142 on which is a trip arm 143 arranged to trip a spring pressed lever 144 as the piston completes its pushingstroke. This lever 144 carries the contact element of a relay 146 that is located in a shunt across the main line 171, and in which is connected the reverse winding of solenoid 140. When relay 146 is closed the valve of unit 115 is reversed and pusher 114 is withdrawn.

-To reverse the valveof unit 113, thereby to l cause the table to be elevated, following withdrawal of pusher 114, extension 142, as here shown as an example, carries a second trip arm 145 arranged'to trip, as the pusher 114 reaches withdrawn position, a spring pressed lever 147. This lever carries the contact ele'- ment of a relay 148 that is located in a shunt across the main line 171 and in which is connected the reverse winding of solenoid 135.

P Whenrelay 148 is closed, therefore, the 'valve of unit 113 isreversed and the table 111 is raised. v

Meanwhile stop 127 has been returned to stopping position in order to hold the table in line with the top strand of the 4conveyor so as to receive a new coilof material. To

raised only, as far as position 11,1 until' the strip is a ain released...

s in t e case of the resistance type of furnace, a preheating and recuperative eect is obtained with this induction type of furnace. That is, the yincoming cold coils on the convyor chains are preheated by the heat given o by the outgoing hot coils and the inducample, the fluid pressure units may have four l one-way-valves operated by a singly wound y 'solen0ids,.

Referring again to the resistance type of furnace, in lace of the single strai ht wires above descri d, wires of hair pin orm may be used. Such av wire is shown in Fig. 11. In the exempliication illustrated, the loop of the .wire is of small or high resistance cross sectionf,t'he' ends being of large or loweresistancecross section. These wires are suported as the vsingle wires are, the two ranches taking the place of tvv-.o single wires in being threaded through or removed from the perforate insulating blocks. In order to economize in wire material, the loops may be alternately reversed so that the complete hair pin wire vdoes not extend the whole length of the furnace chamber. Such an ar'- lrangement is shown schematically in Fig. 12,

which also illustrates the manner of connect- Iing the wires in circuit. As shown in Fig.

' set up by the current 'in the several wires are r the present handling apparatus.

neutralized and loss by induction isy reduced to a mmimum.

In handling coils of metal such as-those above described, at least in the case of metal.

of the lighter gauges, it has been found advisable to firmly bind the coils to prevent them from uncoiling. While the conveyor chains may have ribs or thelike in which the coils seat, such ya construction is considered impracticable with the type of loading and unloading apparatus above described. There is provided a binder suitable for use with ample, the coils may be boundby plain, broad bands of a metal like the conveyor metal, in this instance, nickel chromium alloy. In Figs. 15 and 16 is illustrated a skeleton frame 158 having an annular channel 159 for receiving one end of the coil. This-frame may be made of nickel-chromium alloy or the like.

' With either -type of binder, each coil is firmly bound during its enti eWprocess through the apparatus described.` ith a metal such as nickel chromium alloy there is nodanger of the binders breaking down under continued high temperature and consequently the binders are reliable,and,1asting. 1 i

While nickel chromium alloy has been recited in the specification and claims in con.- nection with various metal parts, it is to be understood that other metals having similar heat resisting characteristics ma be used as equivalents without departing` om the invention. e

There is provided means for controlling the heating temperature of the resistance type of furnace above described. This may be accomplished, for example, by providing' a constant vheat input and varying the conveyor speed in accordance with temperature changes. Although capable' of various constructions, in that here illustrated, inserted in the top wall of the furnace housing is a p rometer 501, its inner end being located a jacent the path of the material on the conveyor. The pyrometer is connected by wires 502, l503 with a pyrometer dial 504 of any suitable construction, 'comprising a pointer that.

`When the temperature at the pyrometerA falls to the lower limit, current through wires 505, 506 opens relay 507 and through the consequent operation of contactor 509 the field resistance 510 is moved in such manner that the motor field is changed to slow down the motor and the conveyor. Assuming a constant input of heat at the furnace resistance wires, when the speed of the conveyor is de-` creased the material to be heated carries away less heat and the furnace temperature rises.

lWhen, onthe other hand, the `temperature at the pyrometer reaches the upper limit, current through wires 506, v513 operates relay 507 and contactor 509 in the reverse direction,

whereby the eld resistance is movedtochange the motor field in a manner to speed up the motor. The consequent increased conveyor speed results in more heat being carried away by the material to be heated and the temperature in the furnace falls.

With a constant heat input and automatic control of the conveyor speed the temperature of the material 'to be heated is automatically controlled within close limits.

There is provided in the motor field circuit a field4 rheostat 516 which can be set by hand to give the approximate motor speed' desired for the volume of material .to be heated. Cur- 8 l a www rent is passed through the resistance heating wires 12 at such -a rate as to bring the furnace been described it will beapparent that it may be duplicated for other conveyors.

The operation of the several forms of apparatus will be clear from the above without further description.

Certain featuresV above described I are claimed in a divisional application Ser. No. 178,645, Patent No. 1,748,465.

What I claim is 1. In a heating apparatus, and in combination, a furnace chamber, conveyor means including an endless conveyor for simultaneously-moving material through said chamber in opposite directions, and electric resistance elements surrounding the several paths of the material moved by said conve or means.

'2. In a heating apparatus, an in combination, a furnace chamber, a plurality of conveyor means including an endless conveyor for movin al plurality of rows of material through sa1d chamber, and electric resistance elements surrounding the paths of the material moved by said conveyor'm'eans.

3. In a heating apparatus, and in combination, a furnace chamber, an endless conveyor for moving material through said chamber, electric resistance elements above said cona veyor and electric resistance elements between the oppositely moving strands of the conveyor. a f

4. In a heating apparatus, andin combination, a furnace chamber, an endl/ess conveyor for moving material through said chamber,

and electric resistance elements arranged above and below said conveyor and between the strands thereof.

5.' In a heating apparatus, and in combination, a furnace chamber, a plurality of endl'ess conve ors for moving material through said cham er, and a. `plurality of electric resistance elements so arranged that each strand of each conveyor is surrounded by resistancey vfor moving material through the chamber and arranged with two units above the other two units, and electric resistance elements around the four walls of the chamber, between each pair of conveyor units vertically and between each pair of units horizontally, whereby each conveyor unit is surrounded by elec-- tric resistance elements.

8. In a heating apparatus, and in combina' tion, a furnace chamber, four endless conveyors in nested relation for moving material through the furnace, and electric resistance elements surrounding each strand of each conveyor.

a 9. yIn a heating apparatus, and in combination, a furnace chamber, perforate supportin means within the chamber 'and a plurallty of electric resistance elements comprising long straight wires, each resistance element being removably threaded through thel perforations of said supporting means.

10. In a heating a paratus, and in combination, a furnace c amber, a plurality of spaced supporting frames in said chamber insulating blocks carried by said frames, an having perforations in alinement lengthwise of the chamber, and electric resistance ele,-l ments ,comprising lon straight Wires threaded through said per orations.

11. In a heating apparatus, and in combination, a furnace chamber, supporting means in the chamber, a plurality of electric resistance elements v comprising long, straight wires, threaded ,through holes in said sup-` porting means and individually removable therefrom, abus bar carried by the chamber said resistance elements and said bus bar.

12. In a heating apparatus, a furnace chamber, electric resistance wires in said chamber for supplying heat thereto, a con- .veyor chain for moving material through the furnace chamber and a plurality of frames in the chamber for supporting said wires and said chains, the frames and conveyor chain being made of an alloy having substantially the same heat resisting characteristics as the resistance wires.

13. In a heating apparatus, a. furnace chamber, electric4 resistance wires in the furnace chamber having a high resistance cross section at the c'entralpart of the chamber and low resistance cross section at the vend thereof, thereby to provide a central heating lwalls, and detachable connections between zone, bus bars, connections between the bus bars and the resistance wires and bus bar leads, said bus bars, connections and leads being located in the relatively cool end portions of the furnace chamber.

14. In a heating apparatus, and in combination, a furnace chamber, heat suppl ing means, and an endless conveyor chain -having reversibly functioningl links, Awhereby both strands of said chain are available for receiving-material to bemoved through the chamber.

15. In a heating apparatus, and in combination, a furnace chamber, an endless conveyor in the chamber, openings in the chamber walls for feeding articles to one strand of the conveyor at one end of the chamber and to the other strand of the conveyor at the .other end of the chamber and for discharging articles from the lirst named strand at the second named end of the chamber and from the second named strand at'the first named end of the chamber, doors for normally closing said openings, and electric resistance elements arranged to supply heatr in zones of varying degree.

16. In a heating apparatus, and in combination, a furnace chamber, conveyor means therein, heat supplying means associated with the chamber, means for feeding material to said conveyor, automatically controlled by the movement of the conveyor, and means for discharging material from the conveyor, automatically controlled by the movement of the conveyed material.

17. In a heating apparatus, and in combination, a furnace chamber, conveyor means therein, heat supplying means 'associated with the chamber, openings in the chamber Walls l for feeding material to and discharging it from the conveyor, feeding means, discharging means, doors for said openings, door operatinof means, and an automatic control for said tfeeding, discharging and operating means.

18. In a heating apparatus, and in combination, a furnace chamber, conveyor means therein, heat supplying means associated vv'ith the chamber, openings in the chamber Walls for feeding material to and discharging it from the conveyor, feeding means including a fluid pressure unit, discharging means including a fluid pressure unit, doors for said openings, door operating means including a fluid pressure unit, solenoids for operating the valve mechanisms of said fluid pressure units and automatically operated relays for controlling said solenoids.

19. In a heating apparatus, and in combination, a furnace chamber, conveyor means' therein, heat supplying means associated with the chamber, openings in the chamber Walls for feeding material to and discharging it from the conveyor, a supply conveyor, means for bringing material up to the feeding open ing, a delivery conveyor, means for carrying material away from the discharge opening, doors for said o enings, door operating means, means for ceding material from the supply conveyor to the' furnace conveyor,

means for dischargin material from the furnace conveyor to sai delivery conveyor and automatic controls for said door-operating means, feeding means and discharging means.

20. In a heating apparatus,y a 4furnace chamber, heat supplyin means, aconveyor for moving material t rou h the furnacel chamber, an electric motor or driving said conveyor, a variableresistance for controlling the field of said motor and heat controlled means for varying said resistance.

21. In a heating apparatus, a furnace chamber, electric resistance `elements for slipplying heat thereto, a conveyor for moving material through the furnace chamber, an

electric motor for driving said conveyor, a pyrometer located adjacent the path of the material in the furnace chamber, a pyromemy hand.

. DAVID L. SUMMEY.

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