US3747908A

US3747908A - Method and apparatus for uncoiling heated coils of steel bar for hot rolling

Info

Publication number: US3747908A
Application number: US00199613A
Authority: US
Inventors: C Anderson
Original assignee: Pennsylvania Engineering Corp
Current assignee: Pennsylvania Engineering Corp
Priority date: 1971-11-17
Filing date: 1971-11-17
Publication date: 1973-07-24
Anticipated expiration: 1990-07-24

Abstract

A billet is hot rolled to convert it to an elongated bar of intermediate cross sectional size. The bar is wound previously into a coil and placed in a furnace to reheat it for subsequent rolling and size reduction. The coil stands on its axis in the furnace with a free upper end thereof accessible to a workman through the furnace door. The furnace has a conical exit passageway in its roof which is connected to a curved guide tube. A starter chain is admitted to the furnace through the tube. The workman engages the free end of the coil with the starter chain which is retracted to withdraw the bar from the coil as a helix of variable diameter and pitch. The uncoiled bar is fed from the guide tube to a secondary rolling mill.

Description

United States Patent 1 Anderson 1 July 24, 1973 METHOD AND APPARATUS FOR Primary E; aminerGerald A. Dost UNCOILING HEATED COILS OF STEEL Attorney-Ralph G. l-lohenfeldt and Fred Wiviott BAR FOR HOT ROLLING [75] Inventor: Charles H. Anderson, McMurray, [57] ABSTRACT A billet is hot rolled to convert it to an elongated bar. [73] Assignee: Pennsylvania Engineering of intermediate cross sectional size. The bar is wound Corporation, Pittsburgh, Pa. previously into a coil and placed in a furnace to reheat it for subsequent rolling and size reduction. The coil [22] Filed 1971 stands on its axis in the furnace with a free upper end [21] Appl. No.: 199,613 thereof accessible to a workman through the furnace door. The furnace has a conical exit passageway in its roof which is connected to a curved guide tube. A 2% 266/1 214/18 25 3 4 starter chain is admitted to the furnace through the 266 tube. The workman engages the free end of the coil 1 0 can l 3 with the starter chain which is retracted to withdraw the bar from the coil as a helix of variable diameter and pitch. The uncoiled bar is fed from the guide tube to a [56] UNITE S STiZT E S I Z' TENTS secondary rolling 734,114 7/1903 Beker 263/3 10 Claims 6 Drawing Figures 1,652,371 12/1927 Miller 266/3 R PATENIEUJIILZMQB sum 1 or 2 ll-l- INVENTOR CHARLES H. ANDERSON TORNEY PArEmEnm 3747. 908

SHEU 2 OF 2 INVENTOR CHA RLES H. AN DERSON ATTORNEY 4' BACKGROUND OF THE INVENTION It is conventional practice in steel rolling mills to roll a steel bar as a continuous length until desired cross sectional dimensions are achieved. By the time the bar is reduced to its final size, it becomes extremely long and is difficult to handle. In some cases, the bar must be formed in serpentine loops in order to minimize the length of the runway in which it is held prior to entry into the first stages of a secondary multiple stage rolling mill. When cross sectional reduction is extensive, it is often necessary to pass the bar through a reheating furnace to make it plastic enough for continuation of the rolling process. The prior practice of passing the bar straight through or in an irregular path through a reheating furnace is wasteful of mill space and thermal energy.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for performing secondary rolling operations of metal bar from a coil of bar instead of a straight billet as has been the prior practice.

Another object of this invention is to improve the economy and efficiency of hot metal bar rolling operations.

Briefly stated, practice of the invention involves subjecting a hot billet to multiple rolling operations and continuously coiling it as it is reduced to an intermediate cross sectional size. Such coils are introduced consecutively into a furnace where they are subjected to reheating. The coils are positioned in the furnace with their axes vertical and with a free end of the bar which comprises the coil exposed. The furnace is provided with an exit passageway in itsroof. The exit passageway communicates with a guide tube which directs the bar to the entry rolls of a rolling mil]. Before the rolling process is initiated, a starting chain is reversely passed through the guide tube until its end reaches the interior of the furnace and is positioned over one of the coils being heated. With a suitable manipulating tool, a

- workman engages the free end of the bar with the end of the starting chain which is then withdrawn, drawing the bar with it. The deformed part at the bar end is then sheared or otherwise disconnected from the starting chainand the bar is fed into the first stage of a secondary rolling mill.

How the foregoing and other more specific objects are achieved will appear from time to time throughout the ensuing more detailed description of the invention taken in conjunction with the drawings.

DESCRIPTION OF THE DRAWINGS FIG. I is a schematic elevation view of the principal components of the bar handling and rolling apparatus;

FIG. 2 is a vertical section of the part of the furnace shown in FIG. 1 through which the bar exits to the secondary rolling mill;

FIG. 3 is a fragmentary view of theleading end of a bar coil together with terminus of the starting chain with which the end may be engagedfor withdrawal of the coil;

FIG. 4 is a fragmentary view, partly in section, showing the leading end of the bar being advanced through the guide tube by means of a starting chain;

FIG. 5 is a plan view of a rotating furnace hearth which is suitable for practicing the invention; and

FIG. 6 shows a coil of rod which is typical 'of those which are processed with the new apparatus.

DESCRIPTION OF A PREFERRED EMBODIMENT In FIG. 1 the reheating furnace is shown partly in section and with parts broken away and is generally designated by the reference numeral 10. The furnace may be electric or a fuel fired type. It comprises a refractory roof 11, an access opening 12 and a door 13 for closing opening 12 as desired. The furnace shown is a rotary type but it could be a continuous furnace or other type as long as coils of bar stock can be introduced into it and advanced therein to a discharge station.

The furnace shown in FIG. 1 has a rotary hearth which is marked with the numeral 14. The shaft which supports the circular hearth 14 at its center and the means for rotating the shaft and the hearth have been omitted since they are conventional. Hearth 14 is provided with several circumferentially spaced coil supporting stands 15. In FIG 1, a coil 16 of bar stock which is to be subjected to further rolling and size reduction is shown standing on support 15 with its coil axis vertically oriented. FIG. 5 illustrates how a number of such coils 16 may be arranged in a circle on hearth 14. These coils are admitted to the furnace and the hearth from a conveyor 17 which is merely symbolized in FIG. 5.

Coils 16 are fed into the furnace from conveyor 17 one after another, as they become available from previous rolling and coiling operations. As shown, hearth 14 is rotated step by step in a counterclockwise direction and coils which are heated on the hearth ultimately reach a station that is in proximity with furnace door opening 12. By the time a coil 16reaches a position where it becomes accessible through door 12, the coil will usually be heated to a temperature of 2,200 to 2,300 F. if the bar stock is steel. Of course, steel is very plastic in this temperature range.

Roof ll of furnace 10 is equipped with a water cooled bar guide device which is generally designated by the reference numeral 18. The device 18 has a tapered or hollow conically'shaped bar guide passageway 19 which diverges toward the interior of the furnace and is connected to a curved guide tube 20. Device 18 is provided with a jacket 21 through which cooling water 22 is circulated from an inlet pipe 23 through the jacket and out through an outlet pipe 24. From inspecting FIG. 2, it will be evident that a smooth transition is made between conical exit passageway 19 and guide tube 20 by virtue of the junction of these elements being curved as indicated at 25.

A starting, chain 26 is provided for'withdrawing the coil of bar stock through'exit passageway 19 and guide tube 20. Except when withdrawal of the bar stock from coil 16 is being initiated, starting chain 26 is normally withdrawn and stored in a guide tube 27 which is horizontally disposed as shownin FIG. l and may be in a suitable trench beneath the level of floor 28. Chain 26 is engaged by a driving sprocket 29 which when rotated clockwise as shown causes chain 26 to advance on supporting

guide tracks

30 and 31 so as to enter the mouth 32 of guide tube 20. The reversible motor for driving sprocket 29 is not shown. It is evident that starting chain 26 may be urged compressively through guide tube until its bar engaging terminus eye 33 is disposed over coil 16 in the furnace and in alignment with the coil 16 axis.

Eye 33 is shown enlarged in FIG. 3 where it may be seen to have an opening 34 which is tapered and provided interiorly with serrations 35. Opening 34 must be large enough to admit free end 36 of whatever size bar stock coil 16 is comprised of. When the hot free end 36 of the coil 16 is passed through eye opening 34, the serrations 35 assist in gripping the bar stock in preparation for withdrawing it through guide tube 20.

As soon as the eye 33 on the end of chain 26 reaches a position over coil 16, the furnace attendant 37 engages the free end 36 of the bar stock with a pair of tongs 38. By using the tongs, the attendant passes the free end 36 of the bar stock through the eye 33 at which time he imparts a sharp bend in free end 36 as depicted clearly in FIG. 4. The width of the bent end approximates the internal diameter of guide tube 20 so that after entry into the guide tube the bend cannot straighten. This prevents disconnection of free end 36 from eye 33 when starting chain 26 is withdrawing the bar through guide tube 20.

Rotation of chain driving sprocket 29 counterclockwise withdraws the starting chain 26 through guide tube 20 at which time it causes the bar to uncoil from coil 16. When the end of chain 26 has passed a shear 40 which is at a starting chain disconnecting station, the shear is operated so as to sever the bar from the starting chain. At this time, the principal part of the bar is between a pair of pinch rolls 41 and 42. Pinch roll 41 may be rotated with a motor, not shown. Pinch roll 42 is mounted on a swivel stand, not shown, so that this roll may be swung to exert a compressive force on the bar stock which is pressed against roll 41. Rotation of roll 41 causes the bar to advance longitudinally at which time the operator engages the free end of the bar with a pair of tongs so as to direct the bar along a line 43 into the entry guide 44 of a rolling mill stand 45. When the bar is engaged between motor driven rolls 46 and 47 of the mill stand, the bar will be frictionally advanced longitudinally at which time swinging pinch roll 42 may be returned to its parked position. The bar is then fed through a series of rolling mills not shown until it has been reduced to the desired cross sectional size.

Within furnace 10, the bar is stripped vertically and axially with respect to coil 16, resulting in a helical strand of variable pitch and diameter because of strand tension from the weight of unsupported turns. Further degeneration of the helical form of the bar is accomplished by the conical shaped exit passageway 19 which introduces additional tensile and bending stresses in the bar and assures that it will deform to a pitch diameter which will pass into the entry end of guide tube 20. Tension imposed on the bar by the rolling mill 45 ultimately causes the bar to assume a helix of very long pitch in guide tube 20 in which case the frictional drag between the bar and the inside of the guide tube is small.

Although the use of eye 33 has been suggested for engaging the free end 36 of the coil with starting chain 26, those skilled in the art will appreciate that various means may be used. For instance, a device, not shown, with jaws that grip the bar automatically, could be used. However, the eye is a simple device for engaging the bar securely because the bent end 36 of the bar is constrained from unfolding by the wall of guide tube 20. The term starting chain as used herein is intended to embrace any means such as a stiff cable or other articulated member which can be fed with a compressive force along the guide means until it enters the furnace and presents an end to which the free end of the coil may be attached.

From the foregoing description, it will be evident that the new apparatus and method results in a reduction of the floor space, equipment and time required for rolling a long, thin metal bar. The method is fast because when one coil of the bar stock is being withdrawn and rolled, the next coil is coming up to temperature so that it may be advanced to the discharge station as soon as the preceding coil is completely removed.

Although a preferred embodiment of the invention has been described in considerable detail, such description is intended to be illustrative rather than limiting, for the invention may be variously embodied and is to be limited only by interpretation of the claims which follow.

I claim:

1. Apparatus for preparing a coil of metal bar stock for reduction of its cross section, comprising:

a. furnace means having means therein for supporting a coil axially so that at least one end of a bar of which the coil is comprised is accessible in the furnace means,

b. bar exit means in the top of the furnace, said exit means having a passageway the entrance end of which is presented to the furnace interior,

0. guide meanscommunicating with said passageway,

d. reversibly translatable starting chain means advanceable by way of said guide means into said furnace for engagement with the end of a coiled bar, whereby retraction of the chain means will strip said bar helically endwise of the coil and withdraw the same through the said guide means.

2. The invention set forth in claim 1 wherein:

a. said guide means is a tubular member having one end connected to the exit end of said bar exit means as aforesaid and its other end terminating near a starting bar means disconnecting station.

3. The invention set forth in claim 1 wherein:

a. the said exit passageway includes a substantially conical member which has its axis directed substantially the same as the axis of the coil in the furnace and has its wide end presented toward the coil.

4. The invention set forth in claim 1 wherein:

a. said coil supporting means in said furnace is adapted to support a coil with its axis vertically disposed, and

b. said exit passageway has a substantially conical cross section which has its axis vertically disposed.

5. Apparatus for handling-a metal bar comprising:

a. a furnace means having a roof,

b. means adapted to support a coil of metal bar in the furnace with the axis of the coil vertically oriented and with a free end of the bar accessible from the top of the coil,

c. a guide means communicating from the exterior of the furnace to the interior thereof through the roof,

d. means adapted to engage the free end of the bar and advance the same along the guide means exteriorly of the furnace, whereby. to uncoil the bar means continuously. 6. The invention set forth in claim 5 wherein:

a. said guide means is a tubular member, and there b. a bar guide device which has a passageway that diverges toward the interior of the furnace at one end and has its other end connected to said tubular guide means.

7. The invention set forth in claim 1 including:

a. a rotary hearth in said furnace means adapted to support a plurality of bar coils with their axes vertically disposed,

b. a door in said furnace adjacent a coil that has attained a predetermined angular position due to rotation of said hearth, an end of said coil being accessible through said door for engagement with said starting bar means, further rotation of said hearth positioning said coil with its axis substantially aligned with the axis of said exit passageway whereupon said bar may be uncoiled and drawn through the guide means. 8. A method of handling a coil of metal bar in preparation for hot rolling the same including the steps of:

a. supporting a coil of metal bar on one of its ends in a furnace so that the coil axis is substantially upright,

b. admitting a starting chain means to the interior of the furnace through an exit passageway which is above the unsupported end of the coil, and

c. engaging a free end of the coiled bar with said starting chain means and then retracting said starting chain means to withdraw the bar endwise of the coil.

9. A method of handling a coil of metal bar in preparation for hot rolling the same including the steps of:

b. passing a starting chain means along a guide means which communicates with the furnace interior so that an end of the chain reaches the interior of the furnace,

c. attaching the free end of the bar to the chain means, and then d. withdrawing the chain means along the guide means so as to uncoil the bar endwise of the coil.

10. The method set forth in claim 9 including the step a. withdrawing the bar through a conically shaped exit passageway which is located between the guide means and the coil.

Claims

1. Apparatus for preparing a coil of metal bar stock for reduction of its cross section, comprising: a. furnace means having means therein for supporting a coil axially so that at least one end of a bar of which the coil is comprised is accessible in the furnace means, b. bar exit means in the top of the furnace, said exit means having a passageway the entrance end of which is presented to the furnace interior, c. guide means communicating with said passageway, d. reversibly translatable starting chain means advanceable by way of said guide means into said furnace for engagement with the end of a coiled bar, whereby retraction of the chain means will strip said bar helically endwise of the coil and withdraw the same through the said guide means.

2. The invention set forth in claim 1 wherein: a. said guide means is a tubular member having one end connected to the exit end of said bar exit means as aforesaid and its other end terminating near a starting bar means disconnecting station.

3. The invention set forth in claim 1 wherein: a. the said exit passageway includes a substantially conical member which has its axis directed substantially the same as the axis of the coil in the furnace and has its wide end presented toward the coil.

4. The invention set forth in claim 1 wherein: a. said coil supporting means in said furnace is adapted to support a coil with its axis vertically disposed, and b. said exit passageway has a substantially conical cross section which has its axis vertically disposed.

5. Apparatus for handling a metal bar comprising: a. a furnace means having a roof, b. means adapted to support a coil of metal bar in the furnace with the axis of the coil vertically oriented and with a free end of the bar accessible from the top of the coil, c. a guide means communicating from the exterior of the furnace to the interior thereof through the roof, d. means adapted to engage the free end of the bar and advance the same along the guide means exteriorly of the furnace, whereby to uncoil the bar means continuously.

6. The invention set forth in claim 5 wherein: a. said guide means is a tubular member, and there is b. a bar guide device which has a passageway that diverges toward the interior of the furnace at one end and has its other end connected to said tubular guide means.

7. The invention set forth in claim 1 including: a. a rotary hearth in said furnace means adapted to support a plurality of bar coils with their axes vertically disposed, b. a door in said furnace adjacent a coil that has attained a predetermined angular position due to rotation of said hearth, an end of said coil being accessible through said door for engagement with said starting bar means, further rotation of said hearth positioning said coil with its axis substantially aligned with the axis of said exit passageway whereupon said bar may be uncoiled and drawn through the guide means.

8. A method of handling a coil of metal bar in preparation for hot rolling the same including the steps of: a. supporting a coil of metal bar on one of its ends in a furnace so that the coil axis is substantially upright, b. admitting a starting chain means to the interior of the furnace through an exit passageway which is above the unsupported end of the coil, and c. engaging a free end of the coiled bar with said starting chain means and then retracting said starting chain means to withdraw the bar endwise of the coil.

9. A method of handling a coil of metal bar in preparation for hot rolling the same including the steps of: a. supporting a coil of metal bar on one of its ends in a furnace so that the coil axis is substantially upright, b. passing a starting chain means along a guide means which communicates with the furnace interior so that an end of the chain reaches the interior of the furnace, c. attaching the free end of the bar to the chain means, and then d. withdrawing the chain means along the guide means so as to uncoil the bar endwise of the coil.

10. The method set forth in claim 9 including the step of: a. withdrawing the bar through a conically shaped exit passageway which is located between the guide means and the coil.