US3779697A

US3779697A - Means and method of heating and handling large coiled billet rod for metal rolling

Info

Publication number: US3779697A
Application number: US00229836A
Authority: US
Inventors: F Alexander
Original assignee: Morgan Construction Co
Current assignee: Siemens Industry Inc
Priority date: 1972-02-28
Filing date: 1972-02-28
Publication date: 1973-12-18
Anticipated expiration: 1990-12-18
Also published as: AR199196A1; DE2301958B2; JPS5147403B2; GB1387521A; JPS48100304A; BR7301522D0; CA968591A; DE2301958A1; ZA728766B

Abstract

Means and method for reheating a very long coiled billet to rolling temperature in a furnace with a moving hearth. The furnace has at its terminal end a heated vestibule in which the coil remains at proper rolling temperature while it is being slowly unwound and delivered to the first stand of a rolling mill.

Description

United States Patent [1 1 Alexander, Jr.

[ MEANS AND METHOD OF HEATING AND HANDLING LARGE COILED BILLET ROD FOR METAL ROLLING [75] lnventor: Frank A. Alexander, Jr., West Boylston, Mass.

[73] Assignee: Morgan Construction Company,

Worcester, Mass.

[221 Filed: 'Feb.28, 1972 211 Appl. No.2 229,836

{52] US. Cl 432/8, 432/54, 432/122 [51] Int. Cl. F27b 9/14 [58] Field of Search 263/3, 7; 266/2.5,

[56] References Cited UNlTED STATES PATENTS 734,114 7/l903 Beker 263/3 Foster et al 263/36 Peirce 263/3 Primary Examiner.lohn J. Camby Attorney-C. Yardley Chittick et al.

[57] ABSTRACT Means and method for reheating a very long coiled billet to rolling temperature in a furnace with a moving hearth. The furnace has at its terminal end a heated vestibule in which the coil remains at proper rolling temperature while it is being slowly unwound and delivered to the first stand of a rolling mill.

10 Claims, 5 Drawing Figures SHEET 1 a; 4

PATENIED nu: 18 ms PAIENIEBncmum 3.779.697

' sum 30F 4 MEANS AND METHOD OF HEATING AND HANDLING LARGE COILED BILLET ROD FOR METAL ROLLING BACKGROUND OF THE INVENTION In the rolling of rod, the metal to be rolled is customarily supplied to the rolling mill in the form of straight billets. The billets, ordinarily in the form of squares or rounds, have been previously rolled from ingots, cut to length, and stored. When needed to supply the rolling mill, the straight billets are placed side by side in a reheating furnace and, when up to temperature, are then fed one after the other to the rolling mill. Billets are customarily cut to 30 to 40 ft. lengths with the length being limited by the width of the reheating furnace.

The size of the billet automatically limits the size of the finished coil of rolled rod. Since it it more economical to produce larger coils of rod if possible, the trend is toward longer and heavier billets. However, since billets come in straight lengths, their size is necessarily limited by the dimensions of the reheating furnace.

In order to provide billets of greater length and weight, it has been suggested that each billet be supplied to the reheating furnace in the form of a coil rather than as a straight length. If the coiled billet were of sufficient length and volume, then coils of rolled rod could be made to any required size. No mechanisms, however, have been available for reheating of a coiled billet in which the size of the billet might be in the order of 600 feet in length, two inches or greater in diameter, and weighing upwards of 7,000 pounds and for thereafter maintaining the coiled billet temperature while feeding it to the rolling mill.

If a large 2 inch diameter section, for example, could be coiled as a loose bundle so that heat could penetrate through the voids in the bundle, then it would be possible to provide rolling mills with extremely long, continuous billets instead of a series of short straight billets of somewhat larger cross-section. The smaller crosssection of the vary long billet would reduce the number of passes required in the rod rolling mill.

SUMMARY OF THE INVENTION The present invention contemplates a means and method for supplying to a rolling mill a succession of very long billets in the form of coils. The billet coils will be moved by a conveyor to a reheating furnace in which there is a moving hearth. The furnace will be long enough so that by the time each coiled billet reaches the discharge position, the temperature of the metal will have been raised to that required for proper rolling. The coiled billet will then be directed from the furnace to an adjacent closed space or vestibule in which the temperature is maintained. Means is provided for slowly unwinding the coil as the billet is delivered from the vestibule to the rolling mill. In a preferred arrangement, while the billet of the first coil is being fed to the mill, the next coil on reaching the end of the furnace will be removed therefrom and held adjacent the first coil in the vestibule at the rolling temperature awaiting its turn.

The invention includes special means for causing unwinding of the coil at a speed matching the required delivery speed to the first stand of the rolling mill so hat there will be no tension on the billet other than that caused by its own weight.

The invention also includes mechanism for reaching into the vestibule to grasp the end of the coiled billet and to draw the end out from the vestibule to feed it into a pair of pinch rolls which are immediately ahead of the first stand of the rolling mill and which thereafter feed the billet to the first stand.

The invention also contemplates that the furnace may be circular or linear and of sufficient size to supply enough heated coiled billets to meet the maximum production capability of the rolling mill. The width of the furnace may be such as to receive a single row of billet coils, or it may be of greater width to receive a plurality of rows of coils. In all cases, the rate of travel of the moving hearth will be such that the billet coils will be brought up to rolling temperature by the time the point of discharge from the furnace is reached.

The mechanism for causing the coil to unwind as the billet leaves the heated vestibule for the rolling mill may include automatic mechanism for varying the rotational rate of the coil support to meet the changing rate of delivery as the billet may be unwinding from the outer or inner periphery of the coil. Sensing devices controlling a variable speed device can affect this result thereby to maintain a constant zero tension in the delivered continuous billet.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a rotary furnace showing the charging and discharging locations of the billet coils.

FIG. 2 is an enlarged plan view of the vestibule showing one billet coil in discharging position.

FIG. 3 is a vertical section taken on the line 33 of FIG. 2.

FIG. 4 is a vertical section taken on the line 4-4 of FIGS. 2 and 3 and showing in addition the billet withdrawing means.

FIG. 5 is a schematic view of an alternate embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Circular furnaces having moving hearths including charging and discharging mechanisms are old. See, for example, Buckholdt U.S. Pat. No. 3,079,135. A linear type furnace having fixed or movable supports carrying the billets as they pass therethrough is shown in the Reissue U.S. Pat. to Alexander No. 27,082.

FIGS. 1, 2, 3 and 4 show the preferred form of furnace, namely a circular furnace, generally indicated at 2 from which the roof part 4 has been broken away in part to show the rotating hearth 6, which carries a succession of billet coils 8 from the charging position 10 to the discharge position 12. The billet coils are brought to the furnace on a conveyor 14 and by a pusher mechanism 16 are pushed from the conveyor 14 onto the rotating hearth 6. The furnace is heated by,

conventional burners, not shown, spaced about the roof and walls.

the next coil 8 therethrough onto the hearth. As soon as the coil is in position on the hearth, the door will be closed to conserve heat in the furnace.

Similarly, when the now heated succession of coils 8 reach the discharge position 12, they will successively be pushed or pulled off the hearth into the vestibule 18 to either of two

positions

24 or 26 by any suitable conventional pushing or extractor mechanisms. Pushers, illustrated at 28 and 30, are constantly in place and their shafts extend through the inner vertical wall of the furnace above the rotating hearth.

Rotation of the hearth is achieved by conventional mechanism suggested in FIG. 1 at 32 which may consist ofa motor with rack and pinion drive. The speed of rotation of the moving hearth can be controlled in relation to the circumference of the hearth, the size of the coil and the furnace temperature so that when each coil reaches the discharge position, it will have been heated to the required rolling temperature. It will be understood that this invention contemplates that the coils may be of any size and weight with the furnaces of appropriate dimensions and heating capacities.

It will also be understood that the hearth could be linear instead of circular, but in either case the billet coils will be brought to rolling temperature by the time they reach the discharge position.

A typical billet coil that would be heated in the furnace would weigh in the order of 6,600 pounds. If it were a two inch round billet, the approximate dimensions of the coil if loosely wound would be: inside diameter 50", outside diameter 70", height 44". Because of the large size and weight of the billet coil, special means is required to enable the billet to unwind slowly as it is fed from the vestibule 18 to the pinch rolls 78 and thence on to the first stand of the rolling mill, not shown.

The mechanism for achieving proper unwinding of the coils in vestibule 18 is shown in FIGS. 2, 3 and 4.

The vestibule includes two

stations

24 and 26, each having related openings and 27 in the floor 40. At each station is a lifting and rotating mechanism generally referred to at 36 and 38 and in vertical alignment with

openings

25 and 27. At the time a coil is pushed from the hearth 6 to its station in vestibule 18, its lifting and rotating mechanism will be in down position as illustrated at 36 in FIG. 3. The coil 8 will rest on the floor 40 of vestibule 18. The lifting and rotating mechanism comprises a cylinder 42 and piston 44 which centrally supports a platform 46. This platform is guided by circumferentially spaced

guideposts

48 and 50. Platform 46 carries a circular track 52 on which rests a set of flanged wheels 54 which support a circular frame 56 which in turn carries a tapered mandrel 58 of such size as to fit within the interior of coil 8.

Mandrel 58 has attached thereto about its lower exterior a plurality of supports 60 which are located at an appropriate vertical position to engage the bottom of coil 8 when the unit 36 is raised. The supports 60 may pass upwardly through the floor 40 by virtue of suitable radial slots 62 in the peripheries of

openings

25 and 27 in the floor 40 (see FIG. 2).

When the coil 8 is needed to begin supplying the rolling mill with the coiled billet, the mandrel 58 is raised by actuation of cylinder and

piston

42 and 44. When in raised position, the parts will then be as shown at the left in FIGS. 2 and 3. All parts of lifting mechanism 38 have been numbered the same as those of lifting mechanism 36 for clarity in explanation, but it is to be understood that these two

lifting mechanism

36 and 38 are provided for lifting and rotating two

separate coils

8 and 8a so that one coil may be discharged to the rolling mill while the other coil is being received from the circular hearth and made ready for discharge to the rolling mill as soon as the preceding coil has been fully discharged.

It will also be appreciated that the two

coils

8 and 8a might be simultaneously discharged if two adjacent rolling mills were available. Ordinarily, however, only a single rolling mill will be supplied, receiving its billets alternately, first from the coil at position 24 and then from the coil at position 26.

When the lifting mechanism has been operated as shown at the left side of FIG. 3, the supports 60 will have moved upwardly above the floor 40 of vestibule l8 and will have picked up the coil 8a raising it a short distance above the floor. As soon as this position has been reached, a power driven set of

gears

64 and 66 are placed in operation which will cause slow rotation of the coil in a clockwise direction as viewed in FIG. 2. The end of the billet 68 is then gripped by a pull-out mechanism shown in FIG. 4 and referred to generally at 70. A door 72 on the front of vestibule 18 is raised to permit the insertion of billet gripping fingers 74 into the upper part of the vestibule 18. The fingers 74 controlled by an operator are carried by a longitudinally movable support 76 having sufficient horizontal and vertical maneuverability so that the end of the billet 68 which is at the top of coil 8a may be readily gripped. As the coil slowly unwinds, the support 76 is slowly withdrawn by the operator and leading end 68 of the billet is directed to a pair of pinch rolls 78 which in turn feed the starting end of the billet to the first stand of the rolling mill, not shown, which is just beyond the pinch rolls 78. The rate of rotation of pinch rolls 78 is timed with respect to the rate of unwinding of the billet from coil 8a.

As soon as the billet has been gripped by the pinch rolls 78, the operator releases the fingers 74 from the billet and the door 72 is dropped to close the entrance to vestibule 18. The door 72 has at its lower part a vertical slot 80 (see FIG. 2) through which the billet passes enroute to pinch rolls 78. Slot 80 also acts as a guide for the billet as it follows its path as shown in FIG. 2. The billet travels in a substantially straight line from its coiled position in vestibule 18 to the pinch rolls 78. The lower part of wall 82 is also slotted in alignment with slot 80 so that as the coil 8a gradually decreases in height, the billet may travel to the pinch rolls 78 over the same general path.

Since the coil 8a is positively rotated by the

gearing

64 and 66, and the pinch rolls 78 are likewise postively driven, it is desirable to include some sensing mechanism for determining the tension present in the billet between coil 8a and the pinch rolls 78. Thus, if coil 8a is delivering the billet faster than the pinch rolls 78 can receive it, the billet will droop in which case the sensors will act to slow down the motor that is driving

gears

64 and 66. On the other hand, if the billet becomes too taut between the coil 8a and the pinch rolls 78 due to the coil rotating too slowly, the sensors will cause the drive for

gears

64 and 66 to speed up slightly thereby to eliminate the undesirable tension. Preferably the billet should have at all times a slight sag between the coil and the pinch rolls so as to be in a state of minimum tension. 1

As soon as the coil 8a has become exhausted, the lifting and rotating mechanism 38 will be lowered to assume the same position as mechanism 36 shown in FIG. 3. In the meanwhile, the mandrel 58 of mechanism 36 will have been raised to lift coil 8 to a position above the floor 40 of vestibule l8 and rotation of

gears

66 and 64 will have commenced. An adjacent door 84 will then be raised and another set of fingers 74 will be inserted to grip the leading end 86 of coil 8 to draw it out and feed it into pinch rolls 88 shown in FIG. 2. The leading end 86 of this new billet is then delivered to the first pair of rolls of the rolling mill and rolling of the rod proceeds as before.

The vestibule is maintained at proper temperature to keep the coiled billet at the required rolling temperature through the use of conventional burners located in the wall and ceiling openings 90 shown in FIGS. 2 and When the term billet coil is used herein it is to be understood to include a coil of metal rod of considerable length in which the cross-section of the rod (which is the billet) may be square, round, hexagonal or otherwise so long as it is suitable for subsequent rolling a rod mill. Moreover, and as previously mentioned, the invention is not limited to circular furnaces. For example, as shown in FIG. 5, the invention also may encompass a furnace 2' having a linear hearth 6' moving between a charging position 10 and a discharge position 12', the latter including a heated vestibule 18' into which heated coils may be pushed from the moving hearth for subsequent uncoiling.

The dimensions of the furnace (circular or linear) may be readily calculated knowing: (I) the production capacity of the rolling mill, (2) the size and density of the billet coil, and (3) the heating capacity of the furnace. For example, with a projected production of 100,000 pounds per hour, the heating capacity of the furnace should be sufficient to heat 15.15 coils per hour of 6,600 lb. coil weight. If we consider the section through the annular area of the above referred to coil as a 10 inch X 44 inch section of about 60 percent density, then the heating rate at conventional reheating furnace temperature should be about 19.5 minutes per inch X 10 X ,0.6 l 17 minutes required time of coil in furnace. Thus, to deliver 15.15 coils per hour to the mill would require a furnace capacity of about 30 coils. With the 70 inch diameter coils spaced 1 foot apart, a circular furnace would be 205 feet in circumference (30 X [70 inch 12 inch]) or 65 feet in diameter.

If a rectangular (linear) furnace were used with the coils in a double row, the length would be about 102 feet X [70inch +12 inch]).

The preceding figures are merely illustrative to show the facility with which any set of conditions of coil size and weight, coil spacing and desired temperature may be related to furnace size, rate of hearth movement,

etc.

While the lifting and coil rotating means associated with the vestibule is arranged to turn the coil about a vertical axis, it will be understood that if desired the coils could be rotated through 90 to unwind from a horizontal axis. Also, the coils when in the furnace could be positioned horizontally rather than in the preferred vertical attitude. These are, however, matters of choice and do not constitute limitations on the following claims.

This disclosure furthermore places no limitation on the size of the vestibule or the number of billet coils therein at any given ime. If the mill, for example, should be a two, three or four strand mill, a corresponding number of coils could be placed in the vestibule for simultaneous feeding of the number of strands in the mill.

Modifications and further applications of the invention will now be apparent to those skilled in the art without departing from the spirit and scope of the invention.

I claim:

1. Means for heating and handling a succession of large billet coils preparatory to rolling to smaller sizes comprising a furnace with a moving hearth, means for depositing a succession of large coils and said hearth, means for supplying heat to each said coil as it moves through said furnace to raise the temperature of each said coil to rolling temperature by the time the said coil has reached the end of its travel through the furnace, a vestibule heated to soaking temperature adjacent the end of the furnace, means for moving each said coil from said furnace at the end of its travel into said vestibule, means for rotating each said coil about its axis in unwinding direction while in said vestibule, and means for feeding the end of said unwinding billet while at rolling temperature through an opening in the wall of said vestibule to the first stand of the adjacent rolling mill.

2. The means set forth in claim 1, said hearth being circular.

3. The means for heating and handling as claimed in claim 1, said hearth being linear.

4. The means set forth in claim 1, said vestibule being large enough to receive a second coil while said previous coil large enough to receive a second coil while said previous coil is unwinding.

5. The means set forth in claim 1, said means for rotating each said coil about its axis in unwinding direction comprising a mandrel shaped to fit within said coil, coils supports associated with said mandrel, lifting means for moving said mandrel and supports upwardly from a position below said coil to a position in which said mandrel is within said coil and said supports engage and lift said coil above said vestibule floor and means for rotating said mandrel and coil when in raised position in unwinding direction.

6. The means set forth in claim 5, said lifting means comprising a piston and cylinder and a circular track carried by said piston, and track rotatably supporting said mandrel and coil.

7. The means set forth in claim 1, said means for feeding the end of said unwinding billet to said first stand comprising pinch rolls adjacent said vestibule opening, billet gripping means for insertion into said vestibule through another normally closed opening to grip the end of said billet and to withdraw said billet end from said vestibule as said coil is rotating and to deliver it to said pinch rolls.

8. The method of heating and handling a large coiled billet preparatory to rolling, comprising the steps of placing the coil in a reheating furnace, moving the coil through said furnace at a rate that will cause the coiled billet to the heated to rolling temperature by the time the said coil reaches the end of its travel through said furnace. removing the coil from the furnace and subjecting the coil to soaking heat in an adjacent vestibule, and rotating the coil slowly and feeding the said billet to a rolling mill as it unwinds from said coil.

9. The method set forth in claim 8, said coil when in said vestibule being raised from the vestibule floor prior to being rotated.

10. Means for heating and handling coils of an elongated product comprising: a furnace having a first opening through which coils are introduced into the furnace and a second opening through which coils are removed from the furnace; a moving hearth for transporting coils through said furnace from said first opencessing.

ag UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3,779,697 bee. 18, 1973 Dated Frank A. Alexander, Jr. Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 6, lines 38 to 40 "while said previous coil large enough to receive a second coil while said previous coil is unwinding" should read while.said previous coil is unwinding-- Col. 6, line 67 "to the heated" should read -to.be heated-- Col. 8, line 4 "leading" should read loading-- Signed and sealed this 23rd day of April 1971+.

(SEAL) Attest:

EDWARD M.FLETCHER,JH. C. MARSHALL DANN Attesting Officer Commissioner of Patents

Claims

2. The means set forth in claim 1, said hearth being circular.

8. The method of heating and handling a large coiled billet preparatory to rolling, comprising the steps of placing the coil in a reheating furnace, moving the coil through said furnace at a rate that will cause the coiled billet to the heated to rolling temperature by the time the said coil reaches the end of its travel through said furnace, removing the coil from the furnace and subjecting the coil to soaking heat in an adjacent vestibule, and rotating the coil slowly and feeding the said billet to a rolling mill as it unwinds from said coil.

10. Means for heating and handling coils of an elongated product comprising: a furnace having a first opening through which coils are introduced into the furnace and a second opening through which coils are removed from the furnace; a moving hearth for transporting coils through said furnace from said first opening to said second opening; a vestibule adjacent to said second opening, said vestibule being heated to an appropriate soaking temperature; means at said first opening for leading coils onto said hearth; means for heating the coils received on and transported through the furnace by said hearth; means at said second opening for moving coils from said hearth out of said furnace and into said vestibule; and means for unwinding the coils in said vestibule and for directing the unwound product to adjacent machinery for further processing.