US3712596A

US3712596A - Method and apparatus for heating an elongated metal workpiece

Info

Publication number: US3712596A
Application number: US00075826A
Authority: US
Inventors: F Cope; J Burrell
Original assignee: Electric Furnace Co
Current assignee: Electric Furnace Co
Priority date: 1970-09-28
Filing date: 1970-09-28
Publication date: 1973-01-23
Anticipated expiration: 1990-01-23

Abstract

A furnace for heating an elongated metal workpiece having a lower surface, which furnace includes a heating chamber and a lower elongated workpiece supporting structure within the chamber. There is provided a series of elements spaced along the supporting structure and means for periodically lifting the workpiece from the structure by the spaced elements and lowering the workpiece onto the structure. In this manner, expansion of the workpiece during the heating cycle can be accommodated without damage to the supporting structure.

Description

United States atent n 1 Cope et al. A

METHOD AND APPARATUS FOR HEATING AN ELONGATED METAL WORKPIECE [75] Inventors: F. Troy Cope, Salem, Ohio; James V. Burrell, Detroit, Mich.

[731 Assignee: The Electric Furnace Company,

Salem, Ohio [22] Filed: Sept. 28, 1970 [21] Appl. No.: 75,826

[52] US. Cl. ..263/6 R [51] ..F27d 3/00 [58] Field of Search ..263/6, 6 A, 46

[56] References Cited UNITED STATES PATENTS l,792,074 2l-l93l- Cochran ..263/6 A 3,511,483 5/1970 Gentry ..263/6 7 8/1968 Morton ..263/6 A [4 1 Jan. 23, 1973 3,450,394 6/1969 Wilde et al. ..263/6 A FOREIGN PATENTS OR APPLICATIONS 1,325,350 3/1963 France ..263/6 A Primary ExaminerCharles J. Myhre Att0rneyMeyer, Tilberry and Body A furnace for heating an elongated metal workpiece having a lower surface, which furnace includes a heating chamber and a lower elongated workpiece supporting structure within the chamber. There is provided a series of elements spaced along the supporting structure and means for periodically lifting the workpiece from the structure by the spaced elements and lowering the workpiece onto the structure. In this manner, expansion of the workpiece during the heating cycle can be accommodated without damage to the supporting structure.

ABSTRACT 5 Claims, 13 Drawing Figures PATENTEDJM 23 I975 SHEET 2 [IF 7 FIG. 3

INVENTOR. F. TROY COPE BY JAMES V. BURRELL ATTORNEYS PATENTEDJAN23 I975 3.712.596

SHEET 3 OF 7 2 w (9 LL.

INVENTOR.

PE HYJAMES V. BURRELL Maya, 7% 5 80%;

ATTORNEYS PMENTEBm 2 3 I915 SHEET 6 0F 7 INVENTOR. F. TROY COPE HYJAMES v. BURRELL Evm ATTORNEYS PATENTEDJAHZB 197s SHEET 5 OF 7 mum INVENTOR. F. TROY COPE JAMES V. BURRELL mhm w wE

hwm

ATTORNEYS PATENTEUJAH 23 1975 SHEET 7 0F 7 FIG. 90

SOO

FIG. 9d

R L m L N E wmm N B 1C- V VI OS RE T M .A F u Y B ATTORNEYS METHOD AND APPARATUS FOR HEATING AN ELONGATED METAL WORKPWCE This invention relates to the art of heating metal workpieces and more particularly to a method and apparatus for heating an elongated workpiece to a temperature for subsequent processing.

The invention is particularly applicable for heating a long steel workpiece for subsequent hot rolling into a smaller strip, and it will be described with particular reference thereto; however, it should be appreciated that the invention has much broader applications and may be used for heating a wide variety of metal workpieces for various purposes.

For many years, it has been accepted practice to reclaim scrap resulting from punch press operations by shipping the scrap back to a steel mill for remelting and forming into ingots. Thereafter, the ingots were heated to the desired rolling temperature and rolled into strip for subsequent use. Recently, it has been suggested that this process could be simplified by providing a long container formed out of same metal as the scrap and having a cover. The scrap is placed into the container and heated to a rolling temperature so that the scrap and container can be passed through a series of mill stands and reduced to the desired strip thickness. This procedure eliminates the requirement for remelting the scrap and the process can be accomplished, in some instances, at the point of use of the strip itself. This procedure for reclaiming steel scrap presents serious problems in developing a furnace capable of raising the temperature of the scrap and container to the proper rolling temperature.

The first requirement for this process is that the filled container, which may have a length of 50 feet, must be heated to the required rolling temperature. As the temperature increases, the power requirements during subsequent rolling decreases. Consequently, it is desired that the long, filled container be heated to a high temperature, in the neighborhood of 2,000F. Preferably, this temperature is approximately 2100F.

At the present time, the furnacing art has not developed a furnace which can heat this long heavy container to the desired rolling temperature while allowing for strip expansion and for convenient removal from the furnace. At first glance, it would appear that heating such a container would present no substantial technical difficulties. The container would be placed into a long furnace and heated to the desired temperature. However, when work was started on this premise immediate technical difiiculties arose. First, when the long container was heated to its rolling temperature, it became extremely flexible and pliable in relation to its weight. Consequently, there is no immediate solution to the problem of removing the long heated container from the furnace. To overcome this difficulty, it was suggested that a roller hearth furnace be employed to heat the elongated container. This roller hearth furnace was to be positioned directly in line with the mill stands so that the container would be moved longitudinally from the furnace to the respective mill stands for rolling. When calculating the size of rolls necessary to support the weight of a container, it was found that the rolls would be so large that they could not be spaced along the bottom of the workpiece. In addition, the rolls must be metallic to support the weight of the container, and this presented a substantial heat sink in the furnace during start-up. For these reasons, the roller hearth type of concept for supporting the metal container within the furnace was not generally acceptable, although it would present a manner of delivering the heated container to subsequent processing equipment. Consequently, before the present invention there was a need for a furnace design which would allow convenient delivery of elongated heated container to the subsequent rolling equipment.

The roller hearth concept also presented another problem. During the heating operation, the container becomes pliable and would sag in between the rolls supporting the container. This would present more difficulties in rolling the heated container from the furnace, and, also, local overloading of the hearth rolls. Another problem presented in heating the long, filled container in a furnace chamber is that the container has a substantial weight and expands during heating. Consequently, if the container is stationary within a furnace and is supported on a fixed structure within the furnace, as the heavy container is heated and expands it tends to damage the supporting structure within the furnace chamber. Even if the supporting structure is a flat surface, the weight of the container and the coefficient of friction between the container and the flat surface would cause buckling of the heated container as it expands during heating. In addition, if a flat surface were used to support the heavy heated container, there would be no efficient way of removing the heated container from the flat surface. It can not be raised by a magnet because it is above its Curie Point. It can not be pushed or pulled because the container would be distorted or collapsed.

All of the above described technical problems involved in designing a furnace for heating a long heavy workpiece for subsequent rolling have been overcome by the present invention which is directed toward a method and apparatus of heating an elongated metal workpiece resting upon a novel supporting structure.

In accordance with the present invention, there is provided an improvement in a furnace for heating an elongated workpiece which furnace includes a heating chamber and a lower, elongated workpiece supporting structure within the chamber. This improvement involves a series of elements spaced along the supporting structure and means for periodically lifting the workpiece from the structure by the spaced elements and lowering the workpiece onto the structure. By lifting and lowering the workpiece during the heating cycle, the forces created by the expanding workpiece are relieved periodically so that they do not damage the supporting structure.

in accordance with another aspect of the present invention, there is provided a method of heating an elongated metal workpiece in a heating chamber which method comprises the steps of supporting the workpiece on a surface, moving the workpiece vertically upwardly from the surface, lowering the workpiece onto the surface and repeating the above-mentioned steps during the heating cycle.

In accordance with still a further aspect of the present invention, there is provided an apparatus for transferring the elongated workpiece from the heating chamber to a subsequent rolling position. This apparatus employs the spaced elements used in lifting and lowering the workpiece during heating. These spaced elements present spaced apart areas along the under surface of the workpiece so that a series of lifting forks can engage the under surface of the workpiece and move it vertically upwardly for transfer to the desired rolling location. These forks are spaced along the length of the workpiece so that the pliable condition of the workpiece does not interfere with the support of the workpiece on the spaced forks.

The primary object of the present invention is the provision of a method and apparatus for supporting an elongated workpiece during heating, which method and apparatus allow expansion of the workpiece.

Another object of the present invention is the provision of a method and apparatus for supporting an elongated workpiece during heating, which method and apparatus facilitates removal of the workpiece from the furnace after heating.

Another object of the present invention is the provision of a method and apparatus for supporting an elongated workpiece during heating, which method and apparatus involves alternately supporting the workpiece on different sets of longitudinally spaced areas.

Yet another object of the present invention is the provision of a method and apparatus for supporting an elongated workpiece during heating which method and apparatus allows removal of the elongated workpiece from a supporting structure by using a series of spaced forks.

Still another object of the present invention is the provision of a method and apparatus for heating an elongated workpiece, which method and apparatus allows for expansion and facilitates transfer of the workpiece to a subsequent processing operation.

These and other objects and advantages will become apparent from the following description used to illustrate the preferred embodiments of the present invention as taken together with the accompanying drawings in which:

FIG. 1 is a schematic, side elevational view illustrating the preferred embodiment of the present invention in one operating position;

FIG. 2 is a schematic, side elevational view similar to FIG. 1 showing the preferred embodiment of the present invention in a second operating position;

FIG. 3 is a partial, schematic, side elevational view similar to FIGS. 1 and 2 illustrating still a further operating feature of the present invention;

FIGS. 4 and 5 are partial, side elevational views illustrating a further embodiment of the present invention;

FIG. 6 is a more detailed side elevational view showing the preferred embodiment of the present invention;

FIG. 7 is a cross-sectional view taken generally along line 77 of FIG. 6;

FIG. 8 is an end view similar to FIG. 7 illustrating further features of the present invention;

FIG. 9 is a schematic layout view showing a further aspect of the present invention; and,

FIGS. 9a-9d are partial schematic views of the equipment shown in FIG. 9 in different operating positions.

Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only and not for the purpose of limiting same, FIGS. 1-3 are used to show certain operating characteristics of the present invention. In

accordance with these figures, there is an apparatus A for heating the workpiece B to the desired temperature for subsequent rolling. This furnace includes a base 10 having an upper surface 12 onto which the lower furnace casing 14 is mounted. Above the casing 14 there is a cover 16 which defines an internal furnace heating chamber 20. A series of heaters 22 in the form of gas burners, raise the temperature of the chamber and workpiece B to the desired temperature. Of course, the burners could be positioned at various locations within the chamber 20. An appropriate sealing structure 24 is provided around the intersection between the casing 14 and cover 16 in a manner common in the furnace art. workpiece B, which is elongated and relatively heavy is supported upon a lower support structure 30 which incorporates a part of casing 14 in the schematic drawing. The support structure 30 includes an upper supporting surface 32 generally defined by a series of transversely extending, first support elements 34 which are fixed with respect to the heating chamber. In accordance with the present invention, the lower support structure 30 includes modifications which overcome this difficulty. Transversely extending first support elements 34 have upper surfaces 34a and are spaced to define transversely extending openings 36 between each element. Within these openings there are provided transversely extending movable workpiece engaging elements 40 having upper surfaces 40a for engaging the under surface of the workpiece B. These movable workpiece engaging elements each include a lower lift rod 50 extending through a rod guide 52. Of course, each element 40 preferably includes at least two of the rods 50. These various lift rods are engaged with the upper surface of a movable frame 54 including at least four spaced guide rollers 56 adapted to ride along vertically extending guide rails 58. For reasons to be explained later, the frame 54 oscillates in a vertical direction to an amplitude as shown in FIG. 2. A variety of arrangements could be used for reciprocating the frame and, thus, the movable elements 40. One of these arrangements is schematically illustrated in FIGS. 1 and 2 as including rollers 60 on frame 54 and lower driven eccentrics 62. As the eccentrics rotate the frame oscillates between a lower position as shown in FIG. 1 and an upper position as shown in FIG. 2.

The operation of the present invention is illustrated in the schematic drawings constituting FIGS. 1 and 2. When the workpiece B is placed within the chamber 20 it rests upon the lower support structure 30. This support structure includes a plurality of fixed first elements 34 and a plurality of movable second elements 40. During heating to the rolling temperature which may be as high as approximately 2100F, the workpiece B expands. This expansion can be destructive if the heavy workpiece is lying upon a flat surface. In accordance with the present invention, when the workpiece is being supported by structure 30 in the manner shown in FIG. 1, the workpiece is contacted by the support surfaces 340. As the workpiece expands, strain is then imposed upon the elements 34. Before these strains become high, the eccentrics 62 rotate to the position shown in FIG. 2. This then raises the support elements 40 so that the workpiece is now supported upon the support surfaces 40a. In this manner, the stresses are relieved from the elements 34, and the workpiece has expanded to a new position when supported by the surfaces 40a. When the temperature of the workpiece causes further expansion, the eccentrics 62 are moved back into the position shown in FIG. 1. In this manner, the weight of the workpiece is relieved from the surfaces 400 and placed again upon the surfaces 340. During the heating cycle, this shifting of the support areas for the workpiece is repeated. Indeed, the eccentrics 62 may be continuously rotated at a selected rate to oscillate the elements 40 between first and second vertical positions.

It will be noted that the workpiece in FIGS. 1 and 2 assumes a serpentine shape, which is substantially exaggerated for elucidation only. The workpiece can actually sag, especially at higher temperatures, between the supporting elements. This would cause substantial damage to the supporting elements if the reversal of support areas was not continuous as indicated. In essence, the workpiece is first supported at a series of spaced transversely extended locations and then supported on a series of other transversely extended locations. By alternating the areas of support, the advantage of allowing expansion without damage to the supporting structure is realized.

It is appreciated that the elements 40, in accordance with the preferred embodiment of the invention, are actually moved belowthe surface 32. It is conceivable in certain installations that the elements 40 could be moved only to coincide the surfaces 40a with the surface 32.

Referring now to FIG. 3, another aspect of the present invention is illustrated. The elements 40 are used to remove the workpiece B from the chamber 20. The cover 16 is removed in a manner to be explained later. Frame 54 is provided with a lifting arrangement formed from

cables

70, 72 fixed at

points

74, 76 respectively on frame 10. These cables are reeled upon driven pulley 78.

Extensions

80, 82 of frame 54 receive pulleys 84, 86. As clearly shown in FIG. 3, when the driven pulley 78 is rotated in a counterclockwise direction, frame 52 is raised a distance b. This forces the support elements 40 into a raised position with the workpiece B substantially above parting line 90 between the furnace casing 14 and the cover, which has been removed. In this manner, a plurality of transversely movable forks 92 shown in phantom lines'in FIG. 3 can move between the elements 40 and under the workpiece B. When the forks are in this position, as will be explained later, they are raised to cradle the pliable workpiece for transfer to a subsequent rolling installation. In thismanner, the support structure for the workpiece itself, including the oscillating elements 40, can be conveniently used for removing the workpiece from the furnace chamber. This is a substantial improvement over other arrangements for handling long heavy workpieces heated to a rolling temperature.

Referring now to FIGS. 4 and 5, a modification of the embodiment schematically illustrated in FIGS. 1-3 is shown. In accordance with this modification, the workpiece support structure includes an upper surface 100 generally defined by the top of fixed elements 102 and a plurality of longitudinally spaced movable elements 104. Each of the movable elements has a pair of downwardly extending lift rods 110 received within appropriate rod guides 112. Only one of these rods and guides are shown for each element. The lower end of the rods are received upon the upper surface of frame 120 which has outwardly extending rollers I22 engaging guide rails 124. Four separate smaller rolls 130, only one of which is shown, are positioned on the frame and coact with driven eccentrics 132 rotated by appropriate drive mechanisms through drive shaft 134. The elements 104 oscillate between two vertical positions as shown in FIGS. 4 and 5. It is noted that the oscillation of these elements is substantially greater than the oscillation of elements shown in FIGS. 1 and 2. The oscillation or reciprocation of the elements 104 accomplishes the same purpose as the movement of elements 40 during the heating cycle; however, by providing a larger amplitude of movement, recesses 140 are formed above elements 104 when these elements are in the position shown in FIG. 4. In a like manner, recesses 142 are provided above the elements 102 when the movable elements 104 are shifted into the position shown in FIG. 5. These recesses are directly below different areas of the workpiece. In accordance with this aspect of the invention, a bank of burners 150 are positioned within the furnace casing opposite to the recesses 140. When these recesses are formed, the burners 150 are actuated to heat the lower surface of the workpiece B directly above the elements 104. Burners 152 are positioned directly opposite to the recesses 142. When the elements 104 are moved into an upward position to form the recesses 142, burners 152 are actuated to heat the workpiece B in the areas directly above elements 102. It is seen that this alternation of the

burners

150, 152 causes a substantial increase in the heating of the workpiece because the lower surface of the workpiece is directly influenced by a burner. Of course, a pair of burners could be spaced on opposite sides of the furnace and adjacent the various recesses. Appropriate controls are used to actuate the burners when the recesses are formed by the elements 104. This arrangement substantially increases the heating effect on the workpieces and contributes to uniform heating. a

The above description relates primarily to the general operating characteristics of the present invention. FIGS. M illustrate the preferred embodiment utilizing these concepts in a practical furnace installation. In accordance with this preferred embodiment, the furnace F includes a furnace chamber 200, workpiece supporting structure 210, workpiece lifting mechanism 220, best shown in FIG. 7, and cover removing mechanism 230. Referring now to the furnace structure 200, there is provided a cover 240 having an upper roof 242 and encased within a generally rectangular steel structure 244. A series of longitudinally spaced burners 246 heat the interior of the furnace. A manifold 247 is coupled with the respective burners and is coupled with a supply by flexible means which will allow movement of the cover, in a manner to be described later. Of course, the burners could be located in a stationary portion of the furnace without requiring movable connections. Lower casing 24B of the furnace is supported on frame 250 and combines with cover 240 to form the internal heating chamber 252.

Referring now to the workpiece supporting structure which forms a major part of the present invention,

there is included stationary end

refractory blocks

266, 262 and stationary, transversely extending refractory blocks 264 having lower reinforcing channels 266,' best shown in FIG. 6. Under the channels 266 are a plurality of transverse support beams 268. These fixed elements define a support surface for the workpiece B, as shown in FIG. 6. Between the fixed block 264 there are transversely extending openings 270 for a purpose to be described later. On each side of the furnace chamber there is provided an appropriate return flue for furnace gases. These flues are numbered 272, 274.

Within the openings 270 reciprocally mounted, transversely extending elements 280 are movable from a lowered position, as shown in FIG. 6 to a raised position as shown in FIG. 8. These elements are substantially identical; therefore only one shall be described, and this description shall apply equally to all. An upper block 282 and a lower block 284 are supported upon a lower frame 286 in which there is secured spaced rod supports 290, 292 on opposite transverse sides of the movable element 280. Guides 298 reciprocally receive the

rods

294, 296. These rods are supported upon a lower reciprocally mounted frame 300 by engagement with longitudinally extending

beams

302, 304. Frame 300 also includes transversely extending

beams

306, 308 for a purpose to be described later. Reciprocation of frame 300 is allowed by providing a plurality of guide rollers 310 coacting with frame mounted rails 312. These rollers can be spaced longitudinally along frame 300. To create the previously mentioned vertical movement during the heating cycle, follower rollers 320 are moved in a vertical direction by cams 322 associated therewith. Each of the rollers is provided with a similar cam, and any number of roller and cam combinations may be provided; however, preferably at least four such arrangements are used. These cams are driven by shaft 324 from gear reducers 326 each of which are driven by a common motor 328.

In operation of the preferred embodiment, during the heating cycle, the cams 322 are rotated at a preselected rate so that the transversely extending movable elements 280 reciprocate between the lowered position shown in FIG. 6 and an upper position with the elements 280 spaced about an inch and onehalf above the blocks 264. In this manner, expansion of the workpiece B can take place as previously discussed.

When the workpiece is to be removed from the heating chamber 252, the workpiece is raised by the

rods

294, 296. This is accomplished by mechanism 220 best shown in FIGS. 7 and 8. A pair of

cables

400, 402 are provided to effect raising of the elements 280. Referring now to cable 400, it extends from a fixed bracket 410 around pulleys 412, 414 and 416 to a driven reel 418. Cable 402 extends from bracket 420 around

rollers

422, 424 to the driven reel 418. As the reel is rotated by a shaft 426, the

cables

400, 402 are reeled onto reel 418. This will raise the

pulleys

412, 422 on the

beams

306, 308. This raises frame 300 to a position substantially higher than its reciprocal movement by cams 322. In this manner, the workpiece B is raised by a series of spaced elements 280 for removal from the furnace, in a manner to be described.

Referring now to the cover removing mechanism, this mechanism is required so that the workpiece can be removed from the heating chamber after the heating cycle. A variety of arrangements could accomplish this function; however, in accordance with the preferred embodiment of the present invention, the cover 240 is first lifted to disengage the end seals 430, 432 and the side seals 434, 436. After this has been done, the cover is moved transversely to expose the workpiece B which is then raised and removed from the furnace. Two lifting

mechanisms

440, 442 are provided on opposite ends of the furnace. Since these mechanisms are substantially the same, only one mechanism will be described in detail and this description will apply equally to the other mechanism.

Upstanding beams

444, 446 are provided below extension of steel structure 244 supporting the cover. A rail 450 extends transversely across the furnace and is mounted upon the upper end of a support plate 452 carrying guide rolls 454 which coact with spaced

guide rails

456, 458 mounted onto the

beams

444, 446, respectively. Of course, two of these structures are provided at opposite transverse sides of the furnace. This supports the beams 450 for vertical movement. To effect the vertical movement, there is provided a follower roll 460 lifted by an eccentric 462 as it is rotated by a drive shaft 464. Of course, two sets of roll and eccentrics are provided on opposite transverse sides of the furnace. Rotation of the eccentrics 462 raise the cover 240 upon rails 450.

To remove the cover from the furnace, wheels 470 ride upon rails 450 which are mounted onto the wheels are drive gears 472 driven by pinions 474 rotated by drive shafts 476. A motor 478 mounted above the cover selectively rotates drive shaft 476 through interconnecting shafts 480, 482. In operation, actuation of the motor 478 after the cover has been lifted moves the cover transversely away from the furnace as shown in FIG. 8. Thereafter, a series of longitudinally spaced forks 490, shown in phantom lines, engage the underside of the workpiece between the upwardly extending, support elements 280. In this manner, the workpiece may be raised and then moved to an appropriate rolling station.

Referring now to FIGS. 9 and 9a9d, the transporting system for the total heating installation is illustrated. As shown in FIG. 8, a bank of longitudinally extending furnaces I, II, III, IV and V are spaced substantially parallel with a supply conveyor S for elongated workpieces and a rolling inlet conveyor R for transferring the heated workpieces into a rolling mill, not shown. The plurality of transversely spaced forks 490, only one of which is shown, extend substantially the same length as the furnace to engage the workpiece in a manner previously described. The hooks are supported on upper rails 500 by a carriage 502 which is movable transverse to the various furnaces and the conveyors S, R. The sequence of operation is as follows. Referring to FIG. 9A, workpiece B has been previously heated in furnace I. The cover 240 has been raised and shifted to the left, and the elements 280 have raised the workpiece B above the walls of the furnace casing. Carrier 502 has moved its spaced hooks 490 between the element 280 for engagement with the under surface of the workpiece B. The workpiece is then raised as shown in FIG. 9B by the forks 490 which now clear the cover 240. Thereafter, the workpiece B is moved by the hooks 490 to the conveyor R. At this time, the workpiece is laid upon the conveyor by downward movement of the forks 490 between the rollers forming the conveyor. This operation is shown in solid and phantom lines of FIG. 9C. Thereafter, the carrier 402 is moved to the right of conveyor S, the forks are lowered and then the conveyor is moved to the left so that the forks come below the workpiece B. Then the workpiece is raised and moved to an appropriate furnace having the cover removed and the elements 280 in the uppermost'position, as furnace I in FIG. 9B. The same operation is performed with respect to all other furnaces so that a plurality of furnaces feed a single conveyor R. Of course, another fork lifting arrangement could be provided on the left of FIG. 9.

When employing the preferred embodiment, as best shown in FIGS. 6-8, the following factors prevailed:

Preferred 50 feet 6 inches 4 feet 40% lbs/ft 2] F.

12 inches 12 inches Range 40-60 feet 4l2 inches 4-6 feet 2000-2200"F. l2-24 inches l2-24 inches 1-3 inches 3-5 min/cycle 1.5 inches 4 min/cycle 3.15 hours Having thus defined our invention, we claim:

1.In a furnace for'heating an elongated metal workpiece having a longitudinal axis, said furnace including a heating chamber, means for heating said chamber,

' and a lower workpiece supporting structure within said chamber, the improvement comprising: said workpiece supporting structure comprising first and second groups of supporting elements spaced axially along said workpiece and extending transversely of the workpiece, each of said elements having workpiece engaging surfaces, and means for periodically and alternately engaging said workpiece with said first and second group of elements, said elements of said first group are movable vertically with respect to said elements of said second group and said means for periodically and alternately engaging said workpiece comprises means for moving said elements in said first group vertically with respect to said elements of said second group between a first position with said workpiece supported on said first groupof elements and a second position with said workpiece supported on said second group of elements, and means for moving said elements in said first group vertically to a third position spaced substantially above said first and second position whereby said workpiece is raised for removal from said chamber.

2. In a furnace for heating an elongated metal workpiece, said furnace including a heating chamber, means for heating said workpiece, and a lower workpiece supporting structure within said chamber, the improvement comprising: said supporting structure including a first group of spaced supporting elements spaced along the length of said workpiece, and each having upper first workpiece supporting surfaces, a second group of spaced supporting elements spaced along the length of said workpiece and each having upper second workpiece supporting surfaces, said elements of said first i0 rou lternati wi h ai elements of 'rl d group zilong the eng ofsaid workpiece an rl mei n s fbr alternately moving said elements in said first group between a first position with said first surface below said second surfaces and a second position with said first surfaces above said second surfaces whereby said workpiece is alternately supported by said first and said second group of elements, including a first group of recesses below said workpiece and above said first surfaces when said first group of elements is in said first position, and a second group of recesses below said workpiece and above said second surfaces when said first group of elements is in said second position and said heating means includes a first bank of burners having a burner directed transverse to said workpiece and into each of a plurality of said first recesses, and a second bank of burners having a burner directed transverse to said workpiece and into each of a plurality of said second recesses.

- 3. The improvement as defined in claim 2 including means for activating said first bank of burners when said first group of elements is in said first position and means for activating said second bank of burners when said first group of elements is in said second position.

4. A method of supporting an elongated workpiece during heating in a heating chamber, said method comprising the following steps:

a. supporting said workpiece by a series of first areas spaced along the length of the workpiece whereby the workpiece sags at second areas between said first areas;

b. lifting said workpiece a first vertical distance by contacting said workpiece at said second areas whereby said workpiece sags generally at said first areas;

c. alternating between steps (a) and (b) during heating of said workpiece; and,

d. lifting said workpiece a second vertical distance substantially greater than said first vertical distance for removal of said workpiece from said chamber.

5. In a furnace for heating an elongated metal workpiece having a lower surface, said furnace including a heating chamber, means for heating said chamber and a lower, elongated workpiece supporting structure within said chamber, the improvement comprising: said supporting structure having a first, generally flat workpiece supporting surface; a plurality of openings spaced along said surface in a direction longitudinal of said workpiece; a support element reciprocally mounted within each of said openings, said elements having upper workpiece engaging surfaces; and power means for reciprocally moving said elements alternately between a first vertical position with said element surfaces below said supporting surface and a second vertical position with said'element surfaces above said supporting surface whereby said workpiece is lifted with respect to said supporting surface, said power means including a frame, means on said frame for engaging said elements, and means for moving said frame in a vertical direction and means for moving said frame and elements upwardly to a position with said element surfaces in a third position substantially above said second position.

Claims

1. In a furnace for heating an elongated metal workpiece having a longitudinal axis, said furnace including a heating chamber, means for heating said chamber, and a lower workpiece supporting structure within said chamber, the improvement comprising: said workpiece supporting structure comprising first and second groups of supporting elements spaced axially along said workpiece and extending transversely of the workpiece, each of said elements having workpiece engaging surfaces, and means for periodically and alternately engaging said workpiece with said first and second group of elements, said elements of said first group are movable vertically with respect to said elements of said second group and said means for periodically and alternately engaging said workpiece comprises means for moving said elements in said first group vertically with respect to said elements of said second group between a first position with said workpiece supported on said first group of elements and a second position with said workpiece supported on said second group of elements, and means for moving said elements in said first group vertically to a third position spaced substantially above said first and second position whereby said workpiece is raised for removal from said chamber.

2. In a furnace for heating an elongated metal workpiece, said furnace including a heating chamber, means for heating said workpiece, and a lower workpiece supporting structure within said chamber, the improvement comprising: said supporting structure including a first group of spaced supporting elements spaced along the length of said workpiece, and each having upper first workpiece supporting surfaces, a second group of spaced supporting elements spaced along the length of said workpiece and each having uppeR second workpiece supporting surfaces, said elements of said first group alternating with said elements of said second group along the length of said workpiece and means for alternately moving said elements in said first group between a first position with said first surface below said second surfaces and a second position with said first surfaces above said second surfaces whereby said workpiece is alternately supported by said first and said second group of elements, including a first group of recesses below said workpiece and above said first surfaces when said first group of elements is in said first position, and a second group of recesses below said workpiece and above said second surfaces when said first group of elements is in said second position and said heating means includes a first bank of burners having a burner directed transverse to said workpiece and into each of a plurality of said first recesses, and a second bank of burners having a burner directed transverse to said workpiece and into each of a plurality of said second recesses.

3. The improvement as defined in claim 2 including means for activating said first bank of burners when said first group of elements is in said first position and means for activating said second bank of burners when said first group of elements is in said second position.

4. A method of supporting an elongated workpiece during heating in a heating chamber, said method comprising the following steps: a. supporting said workpiece by a series of first areas spaced along the length of the workpiece whereby the workpiece sags at second areas between said first areas; b. lifting said workpiece a first vertical distance by contacting said workpiece at said second areas whereby said workpiece sags generally at said first areas; c. alternating between steps (a) and (b) during heating of said workpiece; and, d. lifting said workpiece a second vertical distance substantially greater than said first vertical distance for removal of said workpiece from said chamber.

5. In a furnace for heating an elongated metal workpiece having a lower surface, said furnace including a heating chamber, means for heating said chamber and a lower, elongated workpiece supporting structure within said chamber, the improvement comprising: said supporting structure having a first, generally flat workpiece supporting surface; a plurality of openings spaced along said surface in a direction longitudinal of said workpiece; a support element reciprocally mounted within each of said openings, said elements having upper workpiece engaging surfaces; and power means for reciprocally moving said elements alternately between a first vertical position with said element surfaces below said supporting surface and a second vertical position with said element surfaces above said supporting surface whereby said workpiece is lifted with respect to said supporting surface, said power means including a frame, means on said frame for engaging said elements, and means for moving said frame in a vertical direction and means for moving said frame and elements upwardly to a position with said element surfaces in a third position substantially above said second position.