US2620174A

US2620174A - Billet heating furnace

Info

Publication number: US2620174A
Application number: US24187A
Authority: US
Inventors: Anthony L Passafaro
Original assignee: Allegheny Ludlum Steel Corp
Current assignee: Allegheny Ludlum Steel Corp
Priority date: 1948-04-30
Filing date: 1948-04-30
Publication date: 1952-12-02
Anticipated expiration: 1969-12-02

Description

8 Sheets-Sheet l T HEATING FURNACE www.

MN NN A. L. PASSAFARO BILLE Dec. 2, 1952 Filed April so, 1948 Dec. 2, 1952 A. 1 PAssAl-ARO BILLET HEATING FURNACE 8 Sheets-Sheet 2 Filed April 30, 1948 INVENToR Aff/i0@ L. Passa/1ro l mi Dec. 2, 1952 v A. PAssAFARo 2,520,174

BILLET HEATING FURNACE Filed April 50, 1948 8 Sheets-Sheet 3 /f/f f//f Sfro/re oF De 2, 1952 A. L. PAssAFARO BILLET HEATING FURNACE 8 Sheets-Sheet 4 Filed April 50, 1948 INVENTOR Dec. 2, 1952 A. l.. PAssAFARO 2,620,174

BILLET HEATING FURNACE Filed April 30, 1948 8 Sheets-Sheet 5 Dec. 2, 1952 A. 1 PASSAFARO 2,520,174

BILLET HEATING FURNACE Filed April 50, 1948 8 Sheets-Sheet 6- /sob y d Oa /25 20a /es l? a Dec. 2, 1952 Y A. L.. PAssAFARO 2,620,174

BILLET HEATING FURNACE Filed April 30, 1948 8 Sheets-Sheet 7 falso: J3

AIR SUPPLY INVENTOR FUEL SUPPLY 5 De- 2, 1952 A. PAssAFARo 2,620,174

BILLET HEATING FURNACE Patented Dec. 2, 1952 BILLET HEATING FURNACE Anthony L. Passafaro, Fredonia., N. Y., assignor to Allegheny Ludlum Steel Corporation, a corporation of Pennsylvania Application April 30, 1948, Serial No. 24,187

7 Claims. l

This invention pertains to the heat treatment of metal shapes and to new and improved apparatus and procedure for effecting heat treatment of basic shapes of metal, and particularly, of steel and its alloys.

Heretofore, procedure employed for effecting heat treatment of metal shapes such as billets, e. g., prior to hot working, has involved many disadvantageous and limiting features. It is customary to move or advance billets of a suitable metal, such as stainless steel, for example, through a heat treatment furnace by pushing them transversely in a sde-by-side, substantially abutting relationship into and along the furnace as a continuous layer in such a manner that successive billets are brought up to temperature and then treated.

In present furnace arrangements, the billets are permitted to reach a critical temperature in a preliminary heating-up zone. This is believed to be necessary due to the time required to provide them with a suitable treatment in a subsequent high temperature zone under conditions such that they are heated principally by heat transfer through their upper faces during their movement through such zone. A furnace used for this `purpose ordinarily has a length of approximately 35 feet, and thus, houses a large number of billets that are being advanced therealong.

The billets are moved through by the application of a pusher arm to the last billet at the front or charging end of the furnace, and as a result, they tend to buckle-up, particularly in the annealing zone and adjacent the discharge or back end of the furnace. There is also a tendency for the adjacent billets to stick together 'when at a higher temperature, due to their highly heated condition. In addition, the billets have a tendency to stack-up like straws, and frequently fall endwise down the delivery chute at the back or discharge end of the furnace. When the billets buckle, stack-up, or get out of alignment, it is necessary to shut down the entire furnace and then take all of them out and recharge. Then difficulty is encountered in segregating them, where billet groups of different content are involved, in that their sequential order is lost.

In employing such procedure,v it is apparent that the top portions or faces of the billets have the highest temperature, that their sides will have an intermediate temperature, and that their bottom faces will have a relatively lower temperature. This is one of the reasons why it is necessary to provide a furnace with a high temperature `zone of great length or extent and why excessive scale is formed. Due to the uneven application of heat to the billets, it is apparent that the furnace must be maintained at a much higher temperature than the desired treatment temperature and that such billets, due to the uneven temperature gradient thereacross will have somewhat nonuniform properties. For example, if the inner section of the billet is given the proper heat treatment, the upper face of the billet may be burnt, while the under face of the billet may be undertreated.

The time element is also great in such a procedure and skilled man power is wasted. In the operation of such a furnace, it is customary to shut down at noon and then to advance durnmll billets or frames through the furnace until all the billets have been removed therefrom. One of the reasons for this is that the billets in the preliminary heating zone reach an above-critical temperature and must be removed before the furnace is shut down to prevent damage to them.

As before intimated, it is frequently advisable to treat groups of billets having a particular alloying content. Under the customary procedure, when stacking up occurs, the furnace is shut down, Difficulty is then encountered in determining which billets belong to a particular alloy group. Then it becomes necessary to boretest each billet to determine its content.

Another important limiting feature or disadvantageous feature rests upon the inability to rproperly control the temperature of the billets if it is desired, for example, to give a particular alloy group of billets a final, above normal treatment. It thus becomes necessary to cycle that particular group of billets through another furnace, greatly increasing time, labor, and other costs, and immobilizing such furnace for other work.

To determine the temperature of sucha furnace, it is desirable to employ some suitable temperature indicating means. A Ray-O-Tube and other optical devices have to be placed within a few inches of the billet to work effectively. It is thus apparent that such devices may be damaged when the billets tend to pile up during their progression through the furnace.

It has thus been an object of my invention to provide new and improved procedure for' heat treating metal shapes and particularly basic metal shapes, such as billets, bars, all of which will be hereinafter termed billets Another object has been to provide new and -improvedprocedure for handling billets during their heat treatment.

Another object has been to provide means and procedure for handling billets in a heat treatment furnace such that they may be more quickly and uniformly heated and their` temperature may be more accurately and flexibly controlled.

A further object has been to provide new and improved apparatus for advancing the metal shapes through a heating furnace, and especially, a high temperature zone thereof.

A further object has been to provide a furnace arrangement having more definitely segregated heating-up (low) and heat-treatment (high) temperature zones, such that the temperature of the heating-up zone may be maintained at a value below the critical temperature of the billets, and that it will not be necessary to remove the billets from the heating-up zone when the furnace is shut down.

A further object has been to provide means for effecting a better and more eicient and effective v heat treatment of billets, and more particularly, for turning them during their treatment to more quickly. and. to substantially uniformly bring them to and maintain them at a desired temperature. or temperatures.

Although a basic object of my invention has been. te eliminate the difficulties inherent in the present type of furnace treatments, various other objects will be apparent to those skilled in the art.

In the drawings:

Figure 1 is a. longitudinal section through a furnace constructed in accordance with my invention, showing control apparatus somewhat diagrammatically; this view is taken along the line I-Iv of Figure 3,;

Figure 1A is a view somewhat similar to Figure 1, but showing in outline a modified form of furnace that may be used in connection with my invention;

Figure 2. is a horizontal section taken along the Line. II-II of Figure 1;

Figure 3 is a vertical cross-section taken from the. front of the furnace and along line III-III of'FigureA 1;

Figure 4 is a fragmental horizontal section taken along the line IV-IV of Figure 1 and illustrating apparatus employed in handling. the billets;

Figure 4A is a horizontal sectional detail taken along the line IVA-IVA of Figure 1y andllustrati-ng linkage employed in. connection with the` apparatus for handling the billets;

Figure 4B. is a somewhat diagrammatic side detail of thelinkageof Figure 4A;

Figure-5. is an enlarged side fragmental detail of a pusher rod and yoke assembly of billet handling apparatus;

Figure 6 is a cross-section taken along the line VI-VI of Figure 5;

Figure '7y is a still further enlarged fragmental sectional detail of a collar and pusher rodv assembly, taken along the linesv VII- VII of Figure 6;

Figure 8 is an enlarged fragmental detail taken along the line VIII-VIII of Figure 7';

Figures 9 to 12, inclusive, are enlarged, somewhat diagrammatic side sectional details showing progressive pusher-effected movements of billets through a furnace constructed in accordance with myv invention;

Figure 13 is a somewhat diagrammatic view in elevation of a suitable-fuel and air supply control system that may be used in connection with embodiments of my invention shown in Figure 1,

and by eliminating the separate air supply and control, may be used in connection with the embodiment of Figure 1A;

Figures 14 and l5 are somewhat diagrammatic views in elevation illustrating a limit switch arrangement that may be employed to control motor actuation of the exemplary billet handling apparatus of my invention; Figure 14 illustrates relative operative relationships when the motors are being energized; and, Figure 15 shows the relative relationships after the motors have completed a cycle of movement and while the billets are being heated at their respective positions.

Briefly summarized, I have provided a construction such that the billets may be brought up to a temperature below their critical temperature in -a preliminary or heating-up zone within which they may rest at all times even when the furnace is being shut down. The billets are moved or advanced through a final or high temperature zone by means that may be actuated independently of the pusher means for advancing them through the first zone. That is, it is no` longer necessary to advance dummy frames through the furnace to remove all the billets when it is being shut down. When the furnace is again heated-up or used, the billets in such preliminary zone can then be advanced into the second or critical temperature zone without, as heretofore, rst removing dummies.

Vas one that is sensitive to full scale heat radiation,

can be now employed without danger of breakage. That is, pyrometers can now be mounted closely adjacent to the billets in such a manner as to obtain accurate readings ofY temperature without danger of damage to them. Thus, more accurate and sensitive heat-.indicating equipment can now be employed With safety.

In the furnace embodiment of Figure 1, I have employed air for segregating the temperature zones, and in the embodiment of Figure 1A, I have effected segregation by. furnace roof or ceiling design.

In accordance with. my invention, the billets are individually handled inthe high temperature zone, both from thev standpoint of periodically subjecting their surface. faces to maximum heat, andA from the standpoint of their advance through such zone. One group of billets of a particular content may be fully treated and discharged before a second group is advanced into the high temperature zone. Thus, the time and the temperature of treatment for a second and consecutive group of different composition may be controlled or changed togive them a different treatment, as desired.

The billets in the high, temperature zone may beturned over in about, 70 steps by individual pusher means, as they advance step-by-step through such zone. Their movement through such z one is effected' and coordinated in such a manner that there is no possibilityA of their piling or stacking up, sticking or getting out of alignment. The billets.l are always discharged transversely from the furnace with no possibility of diiiiculty arising from an endwise discharge.

More specifically speaking, in accordance with my invention, I have provided a preliminary zone within which the billets may be maintained at a temperature below their critical temperature and through which they` are advanced in the usual manner by moving them on a substantially horizontal plane in transverse contact with each other by means of a pusher mechanism at the feed-in end of the furnace. That is, the billets may be advanced through this zone by sliding movement imparted through their adjacent faces. Although I also contemplate the same method of advancing as illustrated for the higher tem-- perature zone, I nd that it is not necessary, particularly because of the lower temperature of the billets, and due to the fact that they need not be heated above their critical tempera-ture. They now have little if any tendency to stack or pile up in the preliminary zone, as the pusher means now only needs to provide sufcient force to move the billets through it. The efficiency of the heat treatment in the high temperature zone decreases the needed overall length of the furnace, and thus, it is possible to further reduce the number of billets which are pushed in the ordinary manner by contact with each other through the low temperature zone.

In the high temperature zone, I provide a number of offset or serrated portions or steps therealong and each of these offset portions is provided with pusher means for advancing the billets therefrom and for simultaneously turning them. Each pusher means for each step is preferably operatively connected with the means for the other steps in such a manner that the movement of each billet is coordinated with the movement of the other billets in the zone.

I-t will be apparent to those skilled in the art that any number of high temperature zones may be employed, although for the purpose of simplined illustration, I have shown a single high temperature zone. The linkage employed in actuating the pusher means for each billet, as shown, is preferably constructed in such a manner that there is a speed-up or acceleration during intermediate portions of its stroke cycle. Figures 9 to 12 of the drawings somewhat diagrammatically indicate how the individual billets are advanced and their exposed faces progressively turned over during such movement. It will also be noted that a minimum of two faces are exposed to the direct atmosphere of the furnace by reason of the construction of the steps. This may be contrasted with the billets in the soaking or preliminary treatment zone which have only one major face exposed. The latter type of exposure is typical of the presently known type of high temperature treatment.

As shown in Figure 9, a billet Ia, after it has been pushed upon a leading inclined surface or face of a step A, falls and slides down that surface, so that it turns over at least Then, as it is pushed upwardly along a second or backwardly inclined surface y of the serration or step A, see Figure 10, pivots about its edge, slides down the surface :c of the next step B, and turns to the position shown in Figure 11 with a turnover of at least 30. The total turn-over from step A to step B is about 90. It will be seen that approximately 30 of this turn-over is effected in each instance when the billet rights itself within the bottom of two serrations or steps. That is, the momentum of the slide of the 6 billet may cause it to move an additional 15, in each instance, but in any event, such additional movement is definitely effected when pusher means contacts its lower surface to advance it up the surface y.

Referring again to Figure 9, and to surface faces a, b, c, and d, it will be seen that the previously exposed surface b is still exposed when the billet ISIla has slid down into the bottom'of the first step A, while the previously hidden surface c is now exposed, and a portion of either of the surfaces a or d will be exposed (ordinarily the surface d). a

As the billet I-Ea, see Figure 11, completes its movement into the bottom of the second step B, the face c takes the former position of the face b of the first step A, while the surface d now becomes fully exposed, and either of the surfaces a or b becomes partially exposed. When this same billet I60a reaches the third stepA C, see Figure 12, the face d takes the former position of the face c of the second step Bl, while the face a takes the former position of the surface d, etc. In this manner the billet is progressively turned or rotated and makes a substantially complete rotationin four steps A to D. Ordinarily, about eight steps or two revolutions are sufficient, see Figure 1 of the drawings. Subsequent billets, such as I6b, |600, and I60d are advanced consecutively in the salme manner.

Referring particularly to Figures l, 3, and 4, I have shown a furnace I0 employing my invention which is provided with .a backwardly and upwardly extending furnace front roof portion II. The roof portion II .is connected with a vertically extending front wall part I2a of a backwardly sloped roof portion l2 to provide a complete top enclosure for the furnace. The roof construction may be supported and insulated in any suitable or conventional manner. In Fig- .ure 1, I have shown la, transversely extending structural support I3 for the part I2a of the roof portion I2.

A refractory back wall portion I4 is provided with a pair of vertically-offset series of openings I0 and 1I for receiving fuel jets or nozzles "I2 and 'I3 which will hereinafter be described. It will also be noted that vertical wall part I2a is provided with a series of openings 50 for receiving air jets orv nozzles 5I which will also be later described. The front end of the roof portion II is closed off by a front wall portion I5 that has a transverse opening of sufcient size to permit the admission of billets |60 into the furnace.

As shown particularly in Figures 2v and 3, I also provide suitable refractory, opposite side Wall portions I6 and I6' having, as shown in Figure 2, inspection windows I1 and I1 provided with inspection doors Ila `and I'Ia, respectively, on opposite sides thereof. Vertically-extending channels I8 position and support the side wall portions of the furnace construction.

Referring particularly to Figures 1 and 2, vthe front or feed end of the furnace I0 is provided with a pair of vertically-extending ues I9 and I9' on opposite sides thereof that are, as shown particularly in Figure 2, open to the furnace at their upper ends and at their lower ends are connected `to a common transverse flue I9a, see also Figure 1. The flue ISa is connected to a longitudinally-extending flue Ib which leads to a stack for exhausing spent furnace gases.

Referring particularly to Figure 1, the furnace II) is provided with a longitudinal floor or hearth made up' of transversely-spaced-apart and longitudinall-y extending Carbofrax or other suitable, billet-bearing refractory inserts or rails 20 of requisite strength, see also Figure 2. The refractory rails 20 serve `as support guides for the progression of transversely-positioned billets, generally designated as |60, during their abutting or side-by-side movement along a preliminary or heating-up Zone of the furnace. The refractory guides or rails 20 are positioned in longitudinal slots cut in a refractory support bed portion 2|, and' preferably, extend vertically-upwardly, slightly beyond a horizontal plane representing the upper longitudinally-extending surface of the refractory support bed. The refractory bed portion 2|., made up of nre brick or other suitable material, is supported on a longitudinally-extending refractory hearth portion 22. The hearth portion 22 is supported by a channel floor 23, whose channels extend longitudinally of the furnace. The channel floor 23 is positioned on suitable, transverselyextending channels 24 and I-beams 25', As shown in Figure 3, the beamsk 25, channels 24, 24a, etc., may be supported at their opposite ends on

foundation walls

43 and 45, and extend through an intermediate wall 44. The front end of the furnace oor or hearth construction is shown held in position by a transversely-extending face member 26 which is mounted on. a box-like structural member 26a, see Figurel 1. The concrete foundation is .indicated generally asv 40. The I-beams 25 are also supported on longitudinally-extending, short-length beams 25a that are supported on upwardly-extending transverse wallv portions 4| yand 42 of the foundation 40. The bottom flanges of the transversely-extending support channels 24 are secured to a pulleymounting support plate 21.

Somewhat corresponding portions of the bed construction in the high temperatures and delivery zones of the furnace have been given the same numbers with alphabetical suffixes. That is, in connection with `the high temperature zone, I have shown vertically-backwardly-inclined refractory inserts 20a for the steps or stations A, B, C, etc., a suitably serrated or stepped refractory bed portion 2|a, and a refractory hearth portion 22a which are supported` on a channel floor 23a, see Figures 1 and 3. The inserts 20a are mounted withinV grooves or slotsin the surface y of each step, see Figure 9. The channel floor 23a is mounted on transverselyextending, longitudinally-spaced-apart support channels 24a and these are supported, as shown particularly in Figure 3, on the longitudinallyvertically-extending, transversely-spaced-apart

wall portions

43, 44, and 45 of the. concrete foundation 49. A front pair of the channels 24a carry

bearing plates

21a and 21a for upper ends of I-

beam columns

49 and 49 which, as hereinafter explained, support a. pusherrod actuating mechanism. In a like manner,

columns

49a and 49 are attached at their upper ends to the bearing

plates

21 and 21; these columns provide -a pair of front supports and the pair of columns 49 and 49' provide a pair of back supports for a pusher rod actuating frame. The lower ends of the columns are secured to the foundation 40;

In the delivery zone of the furnace, see particularly Figure 1, the refractory bed portion 2lb supports U-shaped metal guides 29 that are positioned to guide the billets |60 down an outwardly-declining, sloped surface ofthe bed portion 2 lb at the delivery end of the furnace. The bed portion 2lb is supported.onasteppedhearth portion 22h, both of which are supported at one end on a transversely and upwardly-verticallyextending wall portion 41 of the concrete foundation 40 and by a channel floor 23h. The channel floor 23h is supported on short-length, longitudinally-extending beamsv 25h, that are, at one of their ends, mounted' on a bearing step of the upwardly-extending wall portion 41, and are, at their other ends, mounted on a transverselyextending abutment member 35.

An outwardly-declining metal delivery chute or skid member 3| supports the front end of the bed 2 b and is mounted on a transversely-extending, box-like structural member 32. Both the box-like member 32 and the abutment member 30 are positioned on a transversely-extending back wall portion 46 of the concrete foundation 40. The billets |33 are delivered from the delivery member 3| to a conventional form of an endwise-delivery type of roll conveyor 35. The conveyor 35 may be employed to deliver the billets in endwise succession in the usual manner to a hot mill, for example.

As shown in Figure 1, the back wall portion |'4 of the furnace is provided with a U-shaped portion |4a at its lower end which is supported on structural members 33 and which carries a transversely-extending cooling box 34. The structural members 33 may also carry a suitable catwalk. A chain screen or metal curtain 31 is showny extending downwardly from the cooling box 34 and in close adjacency to the skid member 3|, in such a manner as to prevent an excessive loss of heat at the delivery end of the furnace.

I have somewhat diagrammatically indicated conventional horizontal pushers 36, see the righthand end of Figures 1 and 2, that may be ernployed to advance the billets |60 progressively along the relatively flat or planar surface of the preliminary treatment zone of the furnace. The pushers 36 may be actuated hydraulically or mechanically in the usual manner. The billets, when advanced by the pushers 36, move or slide along rails 20 from the front towards the back or delivery end of the furnace, or morev specifically, along substantially the full extent of the heating-up zone of the furnace I. The first billet in the progression (the most advanced one) is pushed into the first station or step A of the heat treatment zone, see Figure 9. The billets are then advanced consecutively along the progression of stations A to. H of the heat treatment zone and are then moved in succession upon the inclined rails 29 of the delivery zone. At the delivery zone, they slide down the rail trackv providcd'bythe U-shaped membersv 29 and the chute member 3| and fall transversely upon the rollers of the conveyor 35.

Referring particularly to Figures 1, 3, 4, and 13, I will now describe suitable means forcontrolling the temperature with the furnace l0. I have shown; see particularly Figures 1 and 3, an

abutting relationship. That is, the ow of cooling air is so controlled asv to maintain the billets which are being moved along the refractory runners or guides 20 at a gradually increasing temperature as they approach the treatment zone or the steps thereof, such as A, B, etc. It will be noted in this embodiment that step or station A is positioned ahead of the converging front end of the furnace top wall or roof portion I2, in order that the billets as they are fed from the refractory runners 20, can then be gradually brought from a preliminary heat up through a critical temperature to a desired final treating temperature. Each of the stations A, B, C, etc., is provided with advancing and retracting pusher means for turning each of the billets in such a manner that they have a substantially uniform heat throughout their cross-sectional areas. A uniform heat is particularly important from the time the billets reach their critical temperature and while they are being treated at or above their critical temperature.

Each of the cooling nozzles may, as shown in Figure 13, be provided with a buttery valve 52 operated in any conventional manner through a lever mechanism by, for example, the amount of electric current energy imparted to a solenoid motor 53. An electrical cable 55 is connected at one end to a control device or box 56, and at its other end is connected in parallel with individual leads 54 of the motors 53. The control box 56 is shown provided with a rheostat control and switch knob 51 for controlling the amount of current supplied to the motors 53, and thus, for controlling the positions of the valves 52 and the amount of cooling uid flow through the nozzles 5I.

A suitable pyrometer tube, such as a Ray-O- Tube 53 is shown extending downwardly through a mounting 59 in the top furnace wall portion II into close adjacency with a billet in the pre liminary or heating-up zone. The tube 58 may be cooled in a conventional manner by cooling water circulation through inlet 6| a and outlet 6 I b of its housing 60. An electrical cable connection 62 extends from the housing 60 of the tube and connects to the panel 55, and particularly, to a visual temperature-reading dial 63 thereof. It will thus be seen that the operator can control the flow of cooling fluid into the preliminary portion of the furnace I6 by adjusting the control knob 51 in accordance with the temperature reading of the dial 63. In this manner, all of the billets within the heating-up zone may be maintained at a temperature below their critical temperature. Air is supplied to the cooling uid nozzles 5| by a supply line S4 and a branch supply line 65, see particularly Figure 13.

I will next describe suitable means for heating the furnace I!) to its desired temperature, and in this connection, particular reference is made to Figures 1, 3, and 13.

The back wall portion I4 of the furnace is provided with an upper series of openings 10 and a lower series of openings 1I within which are mounted

fuel nozzles

12 and 13, respectively. Each of the nozzles 12 is provided with an air intake having a suitable valve, such as a butterfly valve assembly 52a, which is connected between a branch air supply line 65d and the nozzle. The valves 52d may be operated through a suitable lever system by individual solenoid motors 53a that are connected in parallel by leads 54a to a common electrical cable 55a.

In like manner, the other set of nozzles 13 are provided with airV control valves 52h, solenoid motors 53D, and are connected through individual leads 54h in parallel to the cable 55a,

10 The cable 55a, at its other end leads to a control panel provided with a rheostat control and switch knob 8|. The intensity of the flame may thus be adjusted by adjusting electrical current flow to motors 53a and 53h to vary the positions of valves 52a and 52h.

The set of burners 12 are also provided with fluid supply inlets 14a which are connected through electromagnetic, solenoid-operated valves 15a to a branch fuel supply line 16a, and thence, to a main fuel supply line 11. Each of the magnetically-controlled valves 15a has individual electric connections 13a. which are connected in parallel with the main cable 55a. In like manner, the second or lower series of burners 13 are provided with fuel inlets 14h, magnetically-controlled valves 15b, and are connected through such valves to a branch line 1Gb, and thus, to the main fuel supply line 11. In this arrangement, the control motors 53a and 53h for the air supply of the

valves

12 and 13 are set in a suitable relationship with the fuel supply, magnetic control valves 15a and 15b, in such a manner that an yadjustment of the rheostat 8| will simultaneously adjust the flow of air and fuel to each of the

fuel nozzles

12 and 13, in accordance with the desired intensity of flame.

Means is provided, as shown, for indicating the temperature of the billets in the heat treatment zone which may consist of a Ray-O-Tube 32 positioned in the back roof portion I2 of the furnace by a mounting 83. The housing 84 of the tube is provided with cooling fluid inlets and outlets 35a and 85h, and an electric cable. 86 extends therefrom. The cable 86 is connected to a temperature indicating dial 81 of the control panel 80. It will thus be seen that the rheostat knob 8| may be Iadjusted in accordance with the temperature reading of the dial 31 to provide any desired intensity of heat within the furnace by simultaneously adjusting the control of flow of fuel and air to the

nozzles

12 and 13. The specific mechanism used in connection with the temperature control of the furnace is merely illustrative and it will be apparent that any suitable conventional arrangement may be employed, and if desired, that one set of fuel supply nozzles 12, for example, may be independently controlled from the other set 13, in order that one set may be completely extinguished when a much lower temperature is required.

In the modified furnace construction shown in Figure 1A, I have employed prime sufxes to indicate parts that are similar to those of the previously described embodiment. In this `arrangement, I eliminate the cooling air nozzles 50 of the embodiment of Figure l by suitably shaping the roof portion |I-I2' of the furnace. That is, the part II of this roof extends in a substantially parallel plane, relatively close to the billets. The openings 10 and 1 I for the fuel nozzles are mounted on the back wall portion III and can be operated at a lower name intensity, such that a, saving of fuel is effected. The nozzle-like flow of the spent gases between the bed portion 2| and the roof portion II provides the requisite cooling action to insure a lower temperature within the preliminary or heatingup zone.

I will next describe the apparatus or mechanism for moving and turning the billets |66 within the heat treatment zone. In this connection particular reference is made to Figures l, 2, 3, 4, 4A, 5 to 12, and 14 to 15. It will be noted that the actuating mechanism is duplicated on r11 opposite sides of the furnace l0, and for this reason, I have employed prime suffixes to indicate one side and avoid unnecessary repetition of description. It will also be noted that although each side of the mechanism is actuated by

individual motors

90 and 90 that such sides have common linkage or connecting crank shafts which also insure their operation in synchronism. The

motors

90 and 90 are provided as shown in Figures 14 and 15 with a limit switch mechanism 9| operably coupled to crank shaft 92o, such that they are manually started simultaneously, and are stopped automatically and simultaneously after a complete cycle of pusher movement (advancement and retraction) has been accomplished.

The motor 90 is shown mounted on the concrete foundation 40 and is provided with a limit switch generally indicated as 9|. The shaft 90a of the motor 90 is provided with a pinion gear 92a which meshes with and drives a speed reducing gear wheel 92h of a speed reducing unit 92. The unit 92 is also mounted on the foundation 40. The speed reducing gear 02h is secured to a crank shaft 92e to which is attached `a crank 93 that is pivotally connected at 94 to an actuating link 95. The actuating link 95 is at its other end pivotally connected at 96 to a fulcrum lever 91. The lever 91 is at one end fulcrurned on a mount 99 that is secured to an abutment portion 43 of the foundation 40.

At its other end, the fulcrum lever 01, in addition to being pivotally connected to the link 95, is also pivotally connected to a connecting link by the pivot pin 96. A second crank arm |02 is at one end pivotally connected by pivot pin |0| to the other end of the link |00, and at its other end, is operably secured on a cross or crank shaft |03. The cross or crank shaft |03 extends through a mounting |05 in the central wall portion 44 of the foundation and is at its other end secured to a corresponding crank |02 of the part of the mechanism on the opposite side of the furnace. As shown particularly in Figure 4, the shaft |03 is journaled at its opposite ends within mounting brackets |04 and |04. The brackets |04 and |04', as shown particularly in Figures 1 and 4, are secured to flanges 0f vertical upright I-beam column members 49 and 49' on opposite sides of the furnace.

The shaft |03, as shown particularly in Figure 4A, is also provided with a crank arm |0 secured at one end thereon and extending therefrom to actuate a pair of cross arms ||2 which are operably connected to the extending end of the crank arm I0 by pivot pin I i. The other ends of the cross arms |12 are pivotally connected by pins ||3 to one end of a front crank arm H4. The crank arm ||4 is secured on a front, cross or crank shaft |I5. rlhe front cross-shaft H5, in a manner similar to the back cross-shaft |03, extends through a mounting |05a in the central vertical wall portion 44 of the foundation, and is journaled at its opposite ends within bearing mounts |04a and |04a that are secured to anges of the front set of vertical

upright members

49a and 49a, respectively.

The back cross-shaft |03, see Figures l, 4, and 4A, also carries a pusher-frame-actuating crank |06 that is secured thereon at one end and at its other end is operably connected by a pivot pin |01 to a bifurcated mounting lug |08 that projects downwardly from a beam |09 of the frame. The pusher frame is made up of a pair of longitudinally extending I-beams |09 and |09 that are located on opposite sides of the central wall 44 of the foundation, see particularly Figures 1. 4, 4A, 5 and 6. As will be noted, the beam |09 that is located on one side of the furnace l0 is provided with a downwardly-projecting lug mounting |08 adjacent a back end thereof and a similar bifurcated lug |08@ adjacent the front end thereof. In the same manner, the other beam |09' is provided with spaced lugs |08 and |08a.

The front cross or crank shaft |5 is provided with a pusher frame actuating crank |06a which is operably connected at its extending end by a pivot pin |01a to the front lug |08a of the beam |09. It will thus be apparent that both ends of the beams |09 and |09', forming the pusher frame structure for actuating the pusher arms, are simultaneously actuated through the agency of connecting linkage H0, H2, ||3, and ||4 and on one side of the furnace and by similar linkage ||0 to ||4' on the other side of the furnace.

Referring particularly to Figures 3 and 5 to 8, inclusive, it will :be noted that the beam |09 is provided with a series of cross-head members |20 that extend horizontally through its web portion and are secured thereto by suitable weld material 2|. As shown particularly in Figure 4, the cross-heads |20 are located at longitudinally spaced-apart positions along the extent of the beam |09 and correspond in number to the number of stations A, B, etc., at which pusher actuation is to be effected upon the billet.

The cross-head members |20 are provided at their opposite sides with enlarged bore portions |22 each of which is constructed and arranged to receive a lower end portion of a pusher rod shaft |25. The shaft |25 is provided at its other end with a mounting sleeve |26 that extends upwardly with a backward slope through the support channels 24a, the fiooring 23a, the hearth 22a, and the refractory bed 2|a into the bottom of an advanced surface portion :u of each station or step within the heat treatment zone of the furnace. The tubes or sleeves |26 may be suitably cemented within the refractory portions of the furnace and are preferably welded to the furnace hearth metal support structure, such as the channels 24a and the channel floor 23a. It will be noted that the upper end of each tube or sleeve |26 is notched on one side at |21, see Figure 9, to permit the insertion of the refractory or Carbofrax inserts 20a.

As shown particularly in Figures 5 to 8, inclusive, the pusher rod shaft |25 is, at its lower end, provided with spaced-apart, reduced portions |25a, each of which is adapted to receive a mounting collar |23 thereon. As shown particularly in Figure 8, the collar |23 is of two-part or slit construction and its bore is locked in position on the reduced portion |25a by pins |24. As shown particularly in Figure 7, the collars |23 are so mounted with respect to each other that a spacing g is left between the front and rear ends of the cross head |20 to provide suicient play along with the play between the opposite bore walls e and f of the collar |23 to permit a slight pivot movement of the I-beam frame members |09 and |09 when they are advanced from their initial position shown in the full lines of Figure 5 to their advanced position, shown by dot and dash lines of the same figure. In this connection, it will be noted that one side of the cross-head |20 abuts the lower collar |23 when the frame is pulling the rods |25 downwardly and that the opposite side of the cross-head |20 abuts the upper collar |23 when the frame is `l3 moving the rods upwardlyfto the dot and dash line position of Figure 5.

A pair of longitudinally spaced-apart bifurcated pulley mounts |3|a and |32 are secured to and extend downwardly from the plate 21 and rotatably carry the pulleys |28c and |29, respectively. The same counterweight arrangement is employed for the front end of the other side beam |09 and its corresponding parts are indicated by prime suffixes.

' A suitable exemplary time limit switch arrangement 9| for the actuating motors 90 and 90' is shown in Figures 14 and 15. VThe motors 90 and 90' are connected to alternating current supply lines in parallel with each other through a magnetic switch |40. The switch is provided with a pivoted contact arm |36 that is normally urged against a stop |38 by a spring |31; contacts |39 are closed when current flows through the switch coil to energize its electromagnet pole piece |4|. The coil of the switch |40 is energized by a source of direct current |39 through lines |42 and a conductive portion Aof a switch arm 43 that is pivoted at |52. The switch arm |43 may be manually vclosed by a push button |40 and when closed, as indicated Yby the dotted position i of Figure 14, its coil |45 is energized to draw its electro-magnet core `|46 inwardly. The connecting rod |46a that-is Vpivotally connected to the switch arm |43 at |44 then pulls the arm |43 'intocontact vwith points |41. Thus, the coil ofthe switch |40 is close the contacts |39 and energize the

motors

90 and 90. The x,push button |40 is released after such contact is made, and. is returned to position h by spring |40a. When the switch |40 is energized to close the A. C. current supply to the motorsv90 and 90', speed reduction gear 92h .makes one revolution.

motors

90 and 90 to stop, as shown in Figure 15. i

From the above description of exemplary apparatus, it will appear that an actuation of the motors in turn actuates and raises and then lowers the pusher rod frame |09 and |09 to reciprocate the pusher rods |25 within their sleeves |26. And, as shown particularly in Figures 9 to 12, the billets |60 are slid or pushed up the back surfaces y of each station A, B, C, etc. during the rst half of the cycle of movement of the mechanism. In the second or final half cycle, the rods |25 are withdrawn to their original position shown in Figure 9, and the limit switch mechanism 9| is automatically operated to stop the motors. A study of the toggle joint or lever mechanism, see particularly Figure 4B, will disclose that there is a definite intermediate-position acceleration of movement of the pusher rods 25 with deceleration at each end of the reciprocating movement.

As shown in Figures'l, and 9 to 12, the pusher rods |25 slope or incline upwardly and backwardly of the furnace hearth and extend through surfaces m to slide substantially parallel to surfaces y of each station or'step. lThat is, the pusher rods |25 are normally below a longitudinal plane of the hearth, see Figure 9, and project above such plane when they are fully advanced, see Figure 10. i

Although I have for the purpose of illustrating my invention shown in some detail suitable apparatus for controlling the temperature of various zones of the furnace, it will be apparent that any conventional means may be employed dinal series of billet-heating stations defined by the hearth transversely thereof, at least a pair of pushers operatively positioned in a transversely spaced-apart relationship along each station of said series within the hearth'to engagea billet adjacent its opposite end portions and raise it `out of each station and advance it to a succeeding station of said series, said pushers being slidably positioned for reciprocation in an inclined vertical plane within each said station, an operating frame structure positioned beneath the hearth to extend longitudinally therealong, said pushers being mechanically connected Ito" 'said frame structure, and raising yand lowering mech'- anism operatively connected to said frame 'structure to reciprocate said pushers in synchronism.

2. In a heat treatment furnace for metal billets of rectilinear shape, wherein the furnace has enclosing walls deiining a longitudinally-extending and transversely-unobstructed heating .chamber, means for heating the atmosphere of the chamber, and a bottom refractory hearth longitudinally -along the chamber on' which the billets are to be moved: the combination of a successive series of transversely-extending billet-receiving stations in longitudinal progression along the hearth Iand defined thereby, each of said stations having a rearwardly-positioned forwardly-descending surface and a forwardly-positioned and forwardly-ascending surface dening a, valley with respect to each other, the forwardly-positioned and ascending-surface of one station olening an apeX with the rearwardly-positioned forwardly-descending surface of a succeeding station, each of said rearwardly-positioned forwardly-descending surfaces having a suiicient inclination to cause a billet to slide by gravity therealong into the valley defined thereby with the forwardly-positioned and ascending surface of its station, at least a pair of pushers operatively positioned within the hearth for movement from the rearwardly-positioned and forwardly-descending surface of each station along a forwardly-ascending inclined plane substantially -representing the forwardly-positioned and ascending surface of each station for movement along such surface to slidably push a billet upwardly along such surface and pivotally turn it about the 'apex defined with the rearwardly-positioned and forwardly-descending surface of the succeeding station, each pair of pushers being adapted to engage a bottom surface of a billet Within the valley of each station and having a transversely spaced-apart relationship with respect to each other along each station to engage opposite end portions of the billet, an actuating frame structure operably positioned beneath the lhearth to extend lalong opposite longitudinal sides thereof, each of said pair of pushers being operatively positioned on said frame structure, and means for raising and lowering said frame kstructure to reciprocate each pusher of each of said pairs in synchronism with each other and in synchronism with the other pairs along the hearth.

3. In a heat treatment furnace for metal billets of yrectilinear shape, wherein the furnace has enclosing walls dening a longitudinally-extending and transversely-unobstructed heating chamber, means for heating the atmosphere of the chamber and a bottom refractory hearth longitudinally along the chamber on which the billets are to be moved: the combination of a series billet-receiving stations in longitudin-al succession Ialong the hearth and extending transversely of the hearth, said stations being defined by saw tooth-like surfaces of the hearth to provide billet-receiving valleys at each station and billetpivoting Kapexes between succeeding stations, at least a pair of pusher rods operatively positioned to extend upwardly through the hearth in a forwardly-inclined relationship with respect thereto for movement between the valley and the forward apex of each station, the pusher rods of each pair having a transversely spaced-apart relationship with respect to each other to engage a bottom face portion of a billet within the valley of each station and push it upwardly over and pivot 'it about the forward -apex thereof into the valley of the next succeeding station, an actuating structure operatively positioned beneath the hearth and connected to lower end portions of each of said 4pusher rod pairs for reciprocating them within their respective stations in synchronism with respect to each other, and a mechanism operatively connected to said actu-ating structure to reciprocate it and said pusher rod pairs in synchronism to advance billets in each of said stations in a step-by-step relationship from one station to a succeeding station.

4. A furnace as defined in claim 3 wherein, said actuating structure comprises a longitudinally-extending frame positioned adjacent opposite sides of the furnace and connected to one pusher rod of each of said pairs. and a second frame extending longitudinally along an opposite side of the furnace and connected to the other pusher rod of each of said pairs; and said mechanism comprises shaft means extending trans- Versely across the furnace therebeneath and connected to each of said frames through oscillating levers.

5. In a heat-treatment furnace for metal billets of rectilinear shape, wherein the furnace has enclosing walls defining a longitudinally-extending and transversely-unobstructed heating chamber, means for heating the atmosphere of the chamber, and a bottom refractory hearth longitudinally along the chamber on which the billets are to be moved; the combination of a longitudinally progressive series of billet-heating stations defined by the hearth transversely thereof, each of said stations having a forwardly-downwardly declining back portion and a forwardly-upwardly inclining front portion that define an angular valley therebetween, the forwardly-upwardly inclining front portion of each of said stations defining an apex with the forwardly-downwardly declining back portion of the next succeeding station of said series, pushers operatively positioned on forwardly-upwardly inclining planes in the hearth to advance through openings in the forwardly-downwardly declining back portion of each of said stations along the plane of the forwardly-upwardly inclining front portion of each of said stations in engagement with a billet to raise the billet out of the angular valley of each of said stations along the front portion of one station and discharge the billet over the apex and along the back portion of the next succeeding station of said series, and an operating mechanism beneath the hearth and connected to said pushers to reciprocate and advance and retract them through the openings in the back portion of each of said stations.

6. In a furnace as defined in claim 5 wherein, motors are operatively connected to actuate said operating mechanism, and limit switch means is operatively connected to said motors to stop said motors after said pushers have completed a cycle of operation.

7. In a furnace as defined in claim 1 wherein, motors are operatively connected to actuate said raising and lowering mechanism, and limit switch means is operatively connected to said motors to stop said motors after said pushers have completed a cycle of operation.

ANTHONY L. PASSAFARO.

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

UNITED STATES PATENTS Number Name Date 943,373 Barbour Dec. 14, 1909 1,335,648 Blockhouse Mar. 30, 1920 1,861,790 Dreiein June 7 1932 1,921,956 Vickers Aug. 81 1933 1,922,888 Engelbertz Aug. 15, 1933 2,275,265 Mead Mar. 3, 1942 2,451,053 Anderson et al Oct. 12, 1948 FOREIGN PATENTS Number Country Date 303,830 Great Britain (Not accepted but received in U. S. Patent Office, August 21, 1930.)