Automated rolling mill administration system

Information

  • Patent Grant
  • 6240763
  • Patent Number
    6,240,763
  • Date Filed
    Friday, May 21, 1999
    25 years ago
  • Date Issued
    Tuesday, June 5, 2001
    23 years ago
Abstract
An integrated plant for the production of elongated product of relatively small cross section, such as bars and rods, contains an automated system for the administration of rolling mill operation. The system provides for the stand-by storage of mill stands and by-pass tables in proximity to the mill roll pass line. Relatively fixed mill stand transfer devices operate to transfer mill stands to be changed between the mill roll pass line and movable quick change tables intermediate the mill roll pass line and the storage area, and mobile transfer devices operate to move mill stands between the quick change tables and the storage area.
Description




FIELD OF INVENTION




The present invention relates to an integrated plant for the production of elongated metal products, such as bars or rods, or the like. More particularly, the invention involves an arrangement for the integrated, automatic utilization of equipment for rolling elongated metal product including the mill train, the mill stand storage facilities, and mill preparation facilities, and control means for manipulating the equipment between its storage preparation and operational conditions.




BACKGROUND OF THE INVENTION




In the production of elongated metal products such as bars and rods, or the like, size and shape requirements of the products make it necessary that a large number of mill rolls be inventoried and that the mill rolls be frequently changed, either due to the different size and shape requirements of the products being rolled or for maintenance purposes. The changing of rolls or of stands in a mill train has heretofore been a time-consuming and labor intensive operation requiring the use of cranes for manipulating the rolls or stands between the mill train, the storage facilities and the preparation facilities. Consequently, rolling mill administration in such operations has been costly due, not only to equipment and manpower requirements of the activity, but also due to the extensive down time of the mill train required for accomplishment of the activity.




It is to the amelioration of these problems therefore, to which the present invention is directed.




SUMMARY OF THE INVENTION




Accordingly, the present invention provides for use in a mill train for rolling elongated metal product including a plurality of mill stands disposed in-line along a roll pass line, a stand storage area adjacent the roll pass line and a stand preparation area adjacent the stand storage area, apparatus provided for administering the preparation and transfer of mill stands. Such apparatus comprises the stand storage area including a plurality of stacked stand storage compartments disposed in end-to-end relation along a line parallel to the roll pass line, a quick change table extending parallel to the roll pass line and disposed intermediate the roll pass line and the stand storage area, means for moving the quick change table in opposite linear directions parallel to the roll pass line, means for transferring mill stands between the roll pass line and the quick change table, and means for transferring the mill stands between the stand storage area and the quick change table.




According to another aspect of the invention, the means for transferring mill stands between the stand storage area and the quick change table includes a way positioned intermediate the stand storage area and the quick change table and extending parallel thereto, and controllable mobile transfer devices, which preferably may be remotely controllable robots, which are movable along the way.




According to yet another aspect of the invention, the apparatus includes a mill stand set-up means located in a stand preparation area with which the platform communicates for access.




The mill stand organization is employed in a rolling mill train that may be divided into sections including a roughing mill section, an intermediate mill section and a finishing mill section and may include a quick change table associated with each of the mill sections.




It is accordingly a particular object of the present invention to provide an integrated roll mill administration system in which the mill preparation and changes are automated in order to minimize the manual operations associated with this activity.




It is another object of the invention to maximize, to the extent possible, the use of mobile transfer devices or robotics in mill changing operations.




For a better understanding of the invention, its operating advantages and the specific objectives obtained by its use, reference should be made to the accompanying drawings and description which relate to a preferred embodiment thereof.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a schematic representation illustrating an overall plant layout incorporating the invention.





FIG. 2

is a somewhat enlarged schematic of the casting/mill area of the plant shown in FIG.


1


.





FIG. 3

is a plan view of a tunnel furnace and outlet conveyor therefrom of the type suitable for use in the plant shown in FIG.


1


.





FIG. 4

is a sectional view of one embodiment of the tunnel furnace taken along line A—A of FIG.


3


.





FIG. 5

is a sectional view, similar to

FIG. 4

, of another embodiment of the tunnel furnace taken along line A—A of FIG.


3


.





FIG. 6

is a sectional view of the tunnel furnace discharge conveyor taken along line B—B of FIG.


3


.





FIG. 7

is schematic diagram consisting of steps A to H indicating the sequencing of billets within the tunnel furnace for transferring said billets from parallel conveyors into alignment on a single conveyor for conduct to the rolling mill in accordance with the present invention.





FIG. 8

is a schematic layout of the rolling mills/stand storage area of the plant shown in FIG.


1


.





FIG. 9

is a somewhat enlarged illustration of a typical portion of the rolling mill/stand storage area shown in FIG.


8


.





FIG. 10

is a partial perspective view of a typical stand storage robot.





FIG. 11

is a view showing the stands storage area, stand storage robot, quick change device and rolling mill in accordance with the invention.





FIGS. 12 and 13

are a plan view and sectional views, respectively, of the quick change device.





FIG. 14

is a schematic representation of the finishing area for in-line heat treatment as shown in FIG.


1


.





FIG. 15A

is a schematic representation of the thermocontrolled rolling zone.





FIGS. 15B and 15C

are schematic representations of compact variants of the finishing area for in-line heat treatments as shown in FIG.


1


.





FIG. 16

is partial sectional elevation view of a discharging system shown in FIG.


14


.





FIG. 17

is a sectional elevation view of a multilevel annealing furnace.





FIG. 18

is a sectional elevational view of a one-level annealing furnace including a layer preparation system and a discharge system.





FIG. 19

is a partial sectional view of a layer forming system shown in FIG.


14


.





FIG. 20

is a partial elevational view of the cooling bed shown in FIG.


14


.





FIG. 21

is a schematic layout of the finishing area for in-line heat treatment of bars and wire rod shown in FIG.


1


.











DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION




The disclosed invention is particularly directed to a plant


10


for the production of “long products”, i.e. billets or blooms from about forty meters or more in length, used in the production of bars, wire, rod, rebar, or shaped beams or angles, and the like, in which the production machinery utilized is typically smaller in size than that used in the production of sheet material from slabs. As used herein, the word, “billet”, shall include blooms or slabs, or other strand forms produced by a continuous caster and useful in the production of the aforementioned intended product.





FIG. 1

of the drawings shows a schematic representation of an overall plant layout suitable for the practice of the present invention. The described plant comprises a casting/mill entry area A, a rolling mill/stands store area B, a finishing area C for the in-line heat treatment of product; and a finishing area D for the in-line heat treatment of wire rod and bars. A description of the respective areas of the plant is presented hereinafter.




A. The Casting/Mill Entry Area




As shown in the schematic representation of

FIG. 1

, the casting/mill entry area A of the plant includes that area of the plant beginning with the continuous casting equipment


12


and extending essentially to the entrance to the roughing mill stand


16


of the rolling mill


14


.




In

FIG. 2

the production line is shown in somewhat more detail as containing continuous caster equipment


12


which may be operable for producing a pair of billets


18


. The caster equipment


12


comprises a mold


20


which, as is well known, receives molten metal from a tundish (not shown), or the like, and delivers a plurality (here shown as a pair) of billet strands


22


to a conveyor


24


, typically a roll conveyor, suitable for conveying high temperature metal product. Depending upon the ultimate shape of the product to be produced, the caster strands may be billet strands, as embodied in the described line, or they may be of bloom or other dimensions. In either event, the plant


10


, being intended for the production of rolled bar, wire product or other elongated shaped product, will produce strands of predetermined dimensions suitable for the ultimate production of the desired elongated product.




The illustrated production line contains a pair of in-line shears


26


which may be of the blade or flame-type. A quenching box


28


, a cooling bed


30


and a reheat furnace


32


optionally may also be disposed in an “in-line” configuration in the production line. A tunnel furnace


34


, whose principal function it is to heat up and to equalize the temperature of the billets and to bring them to a rolling temperature prior to their being passed to the rolling mill


14


, as hereinafter more fully described, is provided upstream of the roughing mill stand


16


. A dividing and cropping shear


26


is disposed in each of the lines for cutting the product strands to length, which is contemplated to be upwards of forty meters in length.




According to the invention, one of the conveyors, indicated as


24




a


in the drawings, and adapted to receive one of the billet strands


22


from the caster, extends the length of the production line in alignment with the entrance to the rolling mill


14


, as determined by the entrance end of the roughing mill stand


16


. The adjacent conveyor, indicated as


24




b


in the drawings, extends parallel to the first conveyor


24




a


continuously from its position to receive a billet strand and convey it to a position spaced inwardly of the outlet of the tunnel furnace


34


.




Advantageously, a descaling assembly


36


, as shown in

FIG. 2

, can be disposed in conveyor line


24




a


intermediate the discharge end of the tunnel furnace


34


and the entrance to the roughing mill stand


16


. The descaling assembly


36


may be of any well known type but preferably is of the water-operated type including rotary nozzles (not shown) providing a high pressure impact and a low overall rate of water flow so as to reduce to a minimum the loss of temperature from the billet


18


passing to the rolling mill. Between the tunnel furnace


34


and mill inlet, in an advantageous position between the descaler


36


and the mill


14


, an on-line conditioning device


35


can be provided which enables an efficacious elimination of surface defects before entering the mill. The device


35


may comprise in-line grinding systems or in-line scarfers using a special flame for eliminating the billet surface layer.




The tunnel furnace


34


may be heated by any of a number of available heating sources including free flame burners, radiating pipes, induction heaters, or any combination of these, either with or without a protective atmosphere. The tunnel furnace


34


is of a size to receive both conveyors


24




a


and


24




b


and is of a length to accommodate the product being conveyed along the respective conveyors. Exiting the tunnel furnace


34


, as illustrated, is the tunnel furnace discharge end of conveyor


24




a


which is aligned with the entrance to the roughing mill stand


16


.




As shown in

FIG. 3

the longitudinally parallel conveyors


24




a


and


24




b


, which each comprise a series of transversely parallel rollers


35


rotatably driven by motors


37


, are arranged to convey billets


18


from the respective caster strands


22


to the tunnel furnace


34


. In the tunnel furnace


34


the conveying rollers are enclosed within walls having a thermal resistant lining. Openings are provided in the furnace walls to accommodate penetration of connecting shafts extending between the motors and the rollers


35


. As shown best in

FIG. 4

the rollers


35


defining the conveyors


24




a


′ and


24




b


′ may be mutually separated by conductor beams


39


′ whose temperature is maintained by a transfer of heat with respect to fluid circulated through heat transfer line


41


. In an alternative embodiment of the tunnel furnace


34


shown in

FIG. 5

, the conductor beams


39


′ and heat transfer line


41


are eliminated.




According to the invention, means are provided to insure the placement of the billets


18


in close end-to-end alignment at the time of delivery to the rolling mill


16


so that the rolling operation performed on billets from the respective strands


22


is conducted substantially continuously. Thus, as shown, the billet transfer device


38


comprises a series of movable structures


39


that penetrate the furnace wall on one lateral side along substantially the full length of the respective conveyors within the tunnel furnace


34


. In operation, those segments of conveyors


24




a


and


24




b


within the tunnel furnace


34


, identified as segments


24




a


′ and


24




b


′, respectively, produce a running velocity for the billets


18


variable in relation to the continuous feeding cycle phase of the billet to the rolling mill. An illustrative operating cycle is described hereafter.




Consequently, the operating procedure of the disclosed equipment can be appreciated from consideration of Steps (A) through (H) in

FIG. 7

of the drawings. In operation, with billet


18




A


on conveyor


24




b


and billet


18




B


on conveyor


24




a


and lagging billet


18




A


, billet


18




A


enters the tunnel furnace


34


and is received upon conveyor


24




b


′ (Step A). Due to the increased velocity of conveyor


24




b


′, billet


18




A


is moved at a greater velocity to the end of the conveyor and stopped (Step B). In the meantime, immediately prior to the entry of billet


18




B


on conveyor


24




a


into the tunnel furnace


34


, billet


18




A


, by operation of the transfer apparatus


38


, is transferred from conveyor


24




b


′ to conveyor


24




a


′ in forwardly spaced relation from billet


18




B


(Step C). Thereafter, billet


18




A


and billet


18




B


are both conducted on the conveyor


24




a


′ with billet


18




A


being conducted from the tunnel furnace


34


through the descaling assembly


36


toward the entrance to the roughing mill stand


16


and billet


18




B


being simultaneously conducted into the tunnel furnace (Step D).




During this period, a following billet, designated in the drawings as billet


18




B


, which is in lagging relation with respect to billet


18




B


on conveyor


24




a


, has been conveyed by conveyor


24




b


toward the entrance of the tunnel furnace


34


(Steps B to D). Billet


18




A1


, enters the tunnel furnace


34


on conveyor


24




b


to be received on conveyor


24




b


′ as billet


18




B


is leaving the part of the roller table


24




a


which will then be occupied by billet


18




A1


(Step E). As indicated previously, the running speeds of the respective conveyors,


24




a


,


24




b


,


24




a


′ and


24




b


′, are controlled to be time-variable for performing the described working cycle.




As shown in Step (F) billet


18




A


is conducted through the roughing mill


16


at rated rolling speed to the position indicated in the drawing figure. While billet


18




A


is rolled, billet


18




B


is brought to a position immediately adjacent the rearward end of billet


18




A


wherein it is substantially contiguous therewith. This establishes sufficient space on conveyor


24




a


′ rearwardly of billet


18




B


to permit billet


18




A1


to be transferred to conveyor


24




a


′ from conveyor


24




b


′ by the transfer device


38


. As billets


18




A


and


18




B


are conveyed at rated rolling speed through the rolling mill and descaling assembly, respectively (Step G), billet


18




A1


is transferred to conveyor


24




b


′ and moved into close, substantially contiguous relation with the rear end of billet


18




B


(Step H). At this time billets


18




B1


,


18




A1


and


18




A2


are at locations corresponding to billets


18




B


,


18




A


and


18




A1


shown in Step (D) whereupon the operating cycle continues in a repeating manner.




B. Automated Rolling Mill Administration System




With reference to

FIG. 8

of the drawings there is shown a general layout of the rolling mill stands storage area


110


of the described plant


10


.

FIG. 9

illustrates a portion of the equipment in slightly greater detail. As shown, the rolling mill


14


contains sections comprising a roughing mill section


112


, an intermediate mill section


114


and a finishing mill section


116


, each of which sections contains a plurality of rolling mill stands


118


disposed in-line along a roll pass line


120


identified by a dot-dash line. As shown, the rolling mill stands


118


in the respective mill sections are arranged for the rolling of billets


18


produced by the continuous casting equipment


12


whereby, as shown, the axes of the roll sets of adjacent stands


118


in the respective mill sections


112


,


114


and


116


are mutually perpendicularly offset, as is common in the production of elongated metal products, such as bars and rods, or the like, in order to accurately size and shape the product being rolled. Selectively operable shears


117


may optionally be positioned between the respective mill sections.




In addition to the illustrated rolling mill


14


, which may include more or less than the number of rolling mill sections shown, as well as more or less than the number shown of mill stands


118


in each rolling mill section, the concerned region of the plant contains a multi-story stand storage area


122


extending parallel to the roll pass line


120


. The stand storage area


122


comprises a warehousing facility containing a plurality of stacked compartments


124


arranged in side-by-side relation into which mill stands


118


and by-pass tables (not shown) are housed. Such mill stands


118


may be those that have been removed from the rolling mill


14


and await inspection and refurbishing in the facilities adjacent the stand storage area, which includes a washing cabin


126


wherein the stands and mill rolls are cleaned, and a tilting device


128


for rotating the mill stands from horizontal to vertical positions, and vice versa.




At the end adjacent the tilting device


128


is a stand set-up area


130


wherein the mill stands may be disassembled in order to replace rolls and reassembled for placement in the stand storage area


122


.




Intermediate the mill sections


112


,


114


and


116


on the roll pass line


120


and the stand storage area


122


are quick change table means


132


, here shown as being separate quick change tables


132




a


,


132




b


and


132




c


, each disposed adjacent one of the respective mill sections. Mechanism (not shown) is employed to enable the respective quick change tables


132


to move linearly forwardly and backwardly for controlled distances by means of a control device (also not shown).





FIGS. 11 and 12

show the quick changing device


132


which is used for the removal and replacement of the stands. The cross sections of the quick change device are shown in detail in FIGS.


13


(


a


),


13


(


b


),


13


(


c


) and


13


(


d


). The motors


154


, shown in

FIG. 12

, are used to handle the stands (by means, for example, of chain devices) from the quick change device


132


towards the rolling axis and vice versa. The stands move along the rails


152


on wheels


174


(

FIG. 10

) integrated on the stands. The stands which are on the quick change device


13




a


can be transferred on rails


152




b


, and vice versa. From said position, the stands can be collected or positioned by robot


138


. Quick change device


132


can be translated in a direction parallel to the rolling axis on a wheeled system


150


and rails


151


due to control systems not shown.




For transferring mill stands


118


between the respective quick change tables


132


and the compartments


124


of the stand storage area


122


a plurality of mobile transfer devices or robots


138


are disposed to move along a robot way


140


that extends intermediate the quick change tables


132


and the stand storage area


122


and parallel to each. Each robot


138


, a typical one of which is illustrated in

FIG. 10

, has the capability of controllably removing a mill stand from a quick change table


132


and transferring it to any selected compartment


124


of the stand storage area, to the washing cabin


126


for cleaning, to the tilting device


128


or to the stand set-up area


130


. Conversely, the robots


138


also operate to move mill stands


118


from any of the aforementioned facilities to the quick change tables


132




a


,


132




b


or


132




c.






As shown, each robot


138


comprises a frame


166


which is controllably movable on wheels along the robot way


140


and carries oppositely spaced upstanding posts


168


forming guideways for a vertically movable base


170


. The base


170


has a pair of spaced, parallel tracks


172


that cooperate with stand wheels


174


for securing and manipulating a mill stand


176


to be moved along the robot way


140


for transfer between the quick-change table


132


and one or more of the washing cabin


126


, the tilting device


128


, or the stand setup area


130


prior to insertion in a selected compartment


124


of the stand storage area. Of course, a mill stand


118


removed from the rolling mill line can be transferred directly to the stand storage area. A stand operator


178


operates to move stand


176


along tracks


172


.




The operation of the facility is explained by way of an example as follows. Upon completion of the rolling of a product, such as an elongated bar, rod, beam, angle, or the like, employing ten mill stands


118


it is determined that the next product to be rolled requires the use of eight new stands, together with two by-pass tables, to replace the ten mill stands used in the previous product run. It is further determined by a management program that the eight new stands


118


and two by-pass tables (not shown) are available at particular locations in compartments


124


of the stand storage area


122


. At this stage, robots


138


are sequentially moved to positions along the robot way


140


whereby the new mill stands


118


and bypass tables can be sequentially removed from their respective compartments


124


and placed in an assigned position onto the concerned quick change table or tables


132


referred to hereinbefore. The used mill stands


118


are likewise transferred onto the respective quick change tables


132




a


,


132




b


and/or


132




c


by the mill stand transfer devices


134


.




The respective quick change tables


132


, under the control of the management control system, are caused to move linearly in order to sequentially align the new mill stands


118


and bypass tables with their respective assigned positions in the rolling mill train


14


. The used mill stands


118


are similarly moved by the quick change tables


132


to positions from which they are extracted by robots


138


, moved to the washing cabin


126


for cleaning, and thence to stand set-up area


130


or to the stand storage area


122


depending upon the needs of the respective mill stands


118


. The new mill stands


118


and by-pass tables are, in the meantime, moved by mill stand transfer devices


134


to the rolling mill train


14


and are coupled to the relevant driving and control elements whereupon rolling of a new product can commence.




It will be appreciated that there is provided hereby a rolling mill operation in which the respective components are managed by a computer controlled in response to a database which contains particulars of production campaigns, lives of mill rolls and the product-defining channels therein, and the status of the respective components at any given time, whereby the administration of the respective components of the rolling mill is conducted automatically.




C. In-Line Heat Treatment of Stock




As shown in

FIG. 14

of the drawings, the metal product pass line, which is an extension of the roll pass line


120


shown in

FIG. 8

, contains, in-line, a controlling temperature device


212


, a reduction and sizing block


216


, quenching box


218


, cooling bed


220


(optional), induction heaters


222


, an integrated device comprising a layers preparation system


224


, an annealing chamber


226


, and a discharge system


236


. Shears


215


and


217


are also provided for head and tail cutting and for cutting-to-length of the rolled stock. A water box


241


, an on-line shot blasting


239


and a finishing area


240


are provided in-line downstream of cooling bed


220


.




As can be seen in

FIG. 15A

, the temperature controlling device


212


is made up of a set of water boxes


213




a


,


213




b


,


213




c


and an area between the water boxes and the reduction and sizing block


216


, with the aim of equalizing the rolled stock temperature. A set of inductors


215




a


,


215




b


,


215




c


can optionally be provided in an intermediate position between the respective water boxes. Selecting in this way either the water boxes or the inductors it is possible to control and subsequently equalize the rolled stock temperature before entry to reduction and sizing block


216


. The controlling temperature device


212


, together with the sizing and reduction block


216


, permit thermocontrolled rolling of the bars. It is therefore possible to carry out according to the specific requirements either standard rolling, or normalizing rolling, or thermomechanical rolling.




Upon leaving the sizing apparatus


216


the bars are passed to a quenching box


218


in which they are controllably cooled to a predetermined temperature depending upon the desired heat treatment to be performed. Next, the bars may be passed to the induction heated furnace


222


wherein, depending upon the residence time of the bars within the furnace, the bars may be heated for tempering, if desired, or simply heated to an elevated temperature for further processing or for temperature equalization purposes. Alternatively, the bars may simply be diverted through the cooling bed


220


, shown in

FIG. 20

, for cooling to about atmospheric temperature prior to discharge to a bar finishing area


228


. In the arrangement shown in

FIG. 15B

, the induction heaters


222


have been eliminated and heating, if any, of the rolled product takes place directly in the annealing chamber


226


downstream.




Following the induction heated furnace


222


, the bars pass to a layers forming system


224


, shown in

FIG. 19

, from which they are transferred to the annealing chamber


226


. The layers forming system


224


includes an enclosing wall having an opening


224


A forming an inlet through which bars are passed onto a conveyor


224


B for transfer to a layer forming conveyor


224


C. The layers, upon leaving conveyor


224


C, are transferred to a liftable table


224


E which operates to transfer the layers of bars to the annealing chamber


226


. Desirably, the layers forming system


224


includes a pivotally retractable cover


224


F for overlying the conveyor


224


B. The use of a layer forming system similar to the one shown in

FIG. 19

is associated in an advantageous manner to the use of an annealing chamber


226


′ like the one shown in FIG.


17


. In this case the annealing chamber is arranged on two or more levels and is used for high productivity plants. The layers formed with the layer forming system, see

FIG. 19

, are conveyed via a liftable table


224


E inside one of the annealing chamber levels. The layers inside the annealing chamber are moved horizontally so that they cover its whole length in a time equal to that set for the heat treatment. The layer handling device inside the chamber is typically a walking beam system. Treated bar layers are discharged by a device which is symmetrical to the feeding device, an example of which is shown in FIG.


16


. The bar layer is kept in an insulated place up to the bar separation area in order to limit the cooling of same and guarantee good bar straightness. The layers descend from the various levels due to a liftable table


236


A which collects the layer and places it on the transfer


236


B. Separation occurs by means of a device similar to the one for layer preparation, arranging the bars on a cooling bed


236


C without maintenance hoods where the bars can be cooled without causing straightness problems.




Other possible annealing chamber constructions suitable for use in the practice of the present invention are shown and described in U.S. patent application Ser. No. 09/315,847, now U.S. Pat. No. 6,036,485, filed concurrently herewith and the content thereof is incorporated herein by reference.




The integrated device including the layer preparation system


224


, annealing chamber


226


and discharge system


236


, as described, is mainly used for high productivity plants. In low and medium productivity plants said system can be replaced with a system indicated as


226


having only one level, as shown in

FIG. 18

, where the layer preparation system and the discharge system are positioned directly inside the annealing chamber on one level only. In this case the over-all plant layout can be further simplified as shown in FIG.


15


C.




Within the annealing furnace


226


, depending upon the residence time of the bars within the furnace and the furnace operating temperature, the bars can receive a substantial range of heat treatments, such as tempering, workability annealing, spheroidizing-annealing, and slow cooling.




In operation, the general method of the invention for heat treating of steel stock hot rolled in a rolling mill includes the following possibilities conducted in-line with the rolling mill:




1. thermocontrolled rolling of the rolled stock in a thermocontrolled rolling zone constituted by a controlling temperature device


212


and a reduction and sizing block


216


;




2. cutting the rolled stock into pieces of predetermined length;




3. sizing in a reduction and sizing block


216


;




4. quenching the pieces of hot rolled stock in the quenching box


218


;




5. heating the rolled stock in the induction heater


222


;




6. preparing layers of predetermined numbers of pieces of stock in the layers preparation system


224


wherein the number of cut pieces of stock per layer depends on the section of the rolled stock and a following annealing time;




7. tempering and annealing the prepared layers of stock in the annealing furnace


226


;




8. separating the layers into individual pieces of annealed stock in the discharge system


236


; and




9. cooling the heat treated stock in the cooling bed


220


, which, together with the other equipment, may be provided with a protective atmosphere, such as hydrogen/nitrogen or other suitable gases.




The particular times and temperature used in the several steps outlined above are selected for each individual product as dependant, for example, on composition and shape of the rolled product, and on its initially rolled and finally desired microstructure. Some specific examples follow.




For spheroidizing annealing the stock, the rolled stock is subjected to a thermocontrolled rolling using the controlling temperature device


212


and the reduction and sizing block


216


at a temperature of about 750° C. to about 850° C., then passed through the quenching box


218


and through the induction heating furnace


222


wherein no cooling or application of heat occurs therein. The thus-treated stock then is passed through the layers preparation system


224


where layers of cut pieces of stock are prepared. The layers of stock then are passed into the annealing furnace


226


at a temperature of from about 680° C. to about 720° C., and held therein for a time from about one hour to about two hours to spheroidize-anneal the stock. Thereafter, the cut pieces of stock in the layers are separated, and are passed through the cooling bed


220


where the product is cooled to substantially ambient temperature for subsequent in-line finishing, such as sandblasting, cutting to final form, and packaging.




In another variant of the general process, i.e. for shearability or workability annealing of the stock, the process is similar to the previously described process, except that the layers of stock are held in the annealing furnace


226


at a temperature of from about 630° C. to about 680° C. for a time from about 30 minutes to about 40 minutes.




For producing recrystallized annealed stock, the cast and rolled stock is subjected to thermo-controlled rolling in the thermocontrolled rolling zone containing the controlling temperature device


212


and the reduction and sizing block


216


, and the thus-treated stock is annealed in the annealing furnace


226


at a temperature of about 800° C. and at a holding time of about 30 minutes to about 60 minutes.




For producing quenched stock, cut pieces of the cast and rolled stock are quenched in the quenching box


218


. The induction heater


222


, the layers preparation system


224


, and the annealing furnace


222


, the layers preparation system


224


, and the annealing furnace


226


are bypassed and the quenched and tempered stock is passed directly to the cooling bed


220


and therein cooled to substantially ambient temperature.




As a still further example, a method for producing quenched and tempered stock, the cast and rolled stock is quenched in the quenching box


218


, exits the quenching box at a temperature of from about 50° C. to about 150° C., then is optionally passed into the induction heater


222


and heated therein to the entry temperature to the annealing chamber


226


of from about 300° C. to about 500° C. and then held in the annealing chamber, where the temperature rises to about from 600 to 700° C. for a time of from about one hour to about two hours. The thus-treated stock then is passed directly to the cooling bed


220


and therein cooled to substantially ambient temperature.




Various other in-line treatments may be performed, for example, using the annealing furnace


226


for slow cooling of the product when such slow cooling is required for the treated products.




The overall apparatus of the invention, and the flexibility with which the several in-line items of equipment can be used or not used, and the wide range of choices of heating and cooling times and temperatures responsive, for example, to differing product chemistries and microstructures to produce a variety of different products provides a novel and extremely valuable tool in the production of cast and rolled products, such as bar products. As above noted, the invention also provides substantial and significant savings of time and energy costs as compared to conventional off-line heat treatment processes and facilities.




From the cooling bed


220


the processed bars are conducted via conveyor


238


to the water box


241


where they can be quickly cooled, especially after tempering, thereby reducing the stay time in the temperature range where the fragility of the tempering occurs (450-500° C.). If desired, the processed bars can be conducted to on-line shot-blasting device


239


prior to being discharged to the bar finishing area


240


from whence the bars are transferred to storage or to shipment via a transport facility (not shown).




D. Finishing Area for In-Line Treatment of Bars and Wire




With particular reference to

FIG. 21

, there is shown a coil forming and heat treating facility


310


disposed in-line and downstream of the rolling mill


14


and, preferably, emanating from the mill line downstream of the reduction and sizing block


216


. Desirably, larger diameter rod having diameters of from about 10 to about 60 mm, which has been rolled in the rolling mill


14


and sized in the reduction and sizing block


216


, is directed by well known product diverting apparatus into a Garrett line


312


of known construction in which the product is cut into pieces of predetermined length by shear


313


and then is wound into one or more coils on coilers


314


. Alternatively, a second line


316


is particularly adapted for the production of smaller size products, such as wire rod having diameters between about 4 mm and about 25 mm.




As shown in the drawings, the second line


316


desirably contains, in a consecutive in-line relationship, a crop shear


318


, a finishing block


320


, water cooling line


322


, high speed shear


324


and twin module block


326


, which are all operative in the production of smaller diameter wire rod. The second line terminates in coiling apparatus including laying head


328


for forming wire rod spirals, and a roller cooling conveyor


330


along which the spirals are conducted to a coiler


332


.




A ring conveyor


334


defining an essentially closed annular path is located at the ends of the respective rod producing lines


312


and


316


with the coilers


314


and


332


at the ends of the respective lines being closely spaced with respect to each other along one peripheral side of the conveyor. Other work processing stations, including an inspection and testing station


336


, a coil compacting and strapping station


338


and a weighing and discharging station


340


, are disposed at spaced locations about the perimeter of the conveyor


334


. The ring conveyor


334


, which may be of the walking beam or roller table type, permits coils to be conducted to the respective stations around the conveyor and, following discharge of the coils, permits the trestles (not shown) upon which the coils are conveyed and from which they are removed upon discharge, to be returned to positions for receiving coils from coiler


332


. (Trestles are not used for coils wound on coiler


314


.)




This invention contemplates the conduct of in-line heat treatments to the coils conducted by the conveyor


334


. Accordingly, as shown, an elongated annealing furnace


340


is arranged to receive coils to be treated from the conveyor


334


. The furnace


340


preferably has a U-shaped construction being formed of two legs


342


and


344


, each of which has an end


346


and


348


, respectively, opening onto the conveyor


334


. Preferably, end


346


, here shown as defining the inlet to the furnace


340


, is located substantially directly opposite the coiler


332


whereby coils formed on the coiler can be passed directly into the furnace leg


342


.




Advantageously, the furnace


340


may be heated by burners supplied from a fuel source or by induction or other electric heating means. The heat to each leg


342


or


344


of the furnace


340


is independently controlled and, if desired, only one furnace leg can be heated to the exclusion of the other leg.




Other elements which are utilized in the heat treating procedures of the described apparatus include a first quench tank


350


disposed immediately adjacent the coiler


314


of the Garrett line


312


. A second quench tank


352


is disposed intermediate the ends of the furnace


340


, here shown as being adjacent the nexus


354


between the two furnace legs


342


and


344


.




Fans


356


are disposed adjacent one peripheral side of the conveyor


334


whereby coils carried by the conveyor can be cooled by forced air cooling.




In the disclosed arrangement a conveyor offset


358


is optionally provided for conducting coils to a cold finishing facility


360


in which the coils may undergo such processing as pickling, phosphatizing and/or lubricating, or the like. Coils, after processing in this facility are passed to a coil compacting and strapping device


362


prior to discharge from the facility.




The operation of the herein described in-line small section steel stock coiling and heat treating facility for conducting various forms of heat treatment are as follows. For workability annealing coils of stock, which stock has undergone low temperature rolling using water cooling line


322


and twin module block


326


of the second line, the coils are introduced to the annealing furnace


340


immediately after being coiled on coiler


332


. The coils are held in the furnace


340


for up to about two hours and at temperatures of from about 600° C. to about 850° C. The low temperature rolling of the stock before passing it to the furnace


340


significantly reduces the length of holding time for the coils in the furnace.




For workability annealing of the rod stock conducted along the Garrett line


312


, the stock undergoes low temperature rolling using controlling temperature device


212


and reduction and sizing block


216


and, after winding into coils upon coiler


314


at the end of the Garrett line, the coils are conducted along the adjacent side of the ring conveyor


334


to the annealing furnace


340


for heating under conditions similar to those previously described.




For spheroidizing annealing the rolled stock, following thermomechanical or thermocontrolled rolling within a temperature range of from about 750° C. to about 850° C., the stock is wound into coils and immediately passed to the coil annealing furnace


340


for a period of from about one to about two hours for heating at temperatures within the range of from about 680° C. to about 720° C. wherein spheroidizing occurs. After thermal treatment the coils are returned to conveyor


334


for final air cooling.




For solubilization annealing for austenitic stainless steels, the stock, which has undergone normal rolling in the rolling mill


14


, is coiled by coilers


314


at the end of the Garrett line


312


at a temperature of about 900° C. and immediately passed along conveyor


330


to the coil annealing furnace


340


for heating to about 1000° C. and for the time, between about thirty and sixty minutes, to achieve solution annealing. Typically this procedure will be formed in one leg


342


of the furnace


340


whereupon the coils, after achieving solution annealing, are quenched in the quench tank


352


and thence returned to the conveyor to be conducted to a point of final processing.




For recrystallization of ferritic steels the process is similar to that performed for solubilization annealing of austenitic stainless steels, except that the coils are heated only to within the range of from about 700° C. to about 800° C. in the coil annealing furnace


340


before quenching in quench tank


352


.




When quenching and tempering is to be conducted on larger diameter rod material, the stock, after undergoing conventional rolling or thermocontrolled rolling in the section including the rolling mill


210


, the controlling temperature device


212


and the reduction and sizing block


216


is coiled at a temperature of about 800° C. on the coilers


314


of the Garrett line


312


. Immediately after coiling, the coils are quenched in quench tank


350


to a temperature of about 100° C. Thereafter, the coils are conducted by conveyor


334


to the coil annealing furnace


340


to be heated to the tempering temperature of between about 700° C. and 500° C. for a period of one to two hours. The coils are thereafter air cooled on the conveyor


334


before being passed for further processing or to discharge.




It is contemplated that patenting of the wire rod produced on the second line


316


can be performed by thermomechanically rolling the stock at about 850° C. and thereafter subjecting it to forced air cooling by fans placed in the roller cooling conveyor


330


prior to coiling.




It should be appreciated that following all of the foregoing forms of heat treatment, the coils are returned to conveyor


334


for transport to areas of further processing, as for example via conveyor offset


358


to the cold finishing facility


360


and final packaging by the compacting and strapping device


362


prior to shipment or storage.




It will be understood that various changes in the details, materials and arrangements of parts which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.



Claims
  • 1. In a mill train for rolling elongated metal product including a plurality of mill stands disposed in-line along a roll pass line, a stand storage area adjacent said roll pass line and a stand preparation area adjacent said stand storage area, apparatus for administering the preparation and transfer of mill stands comprising:said stand storage area including a plurality of stand storage compartments disposed in end-to-end relation along a line parallel to said roll pass line, at least one quick change table, each associated with a plurality of stands of the mill train, extending parallel to said roll pass line and disposed intermediate said roll pass line and said stand storage area, means for moving each said quick change table in opposite linear directions parallel to said roll pass line, means for transferring said mill stands between said roll pass line and each said quick change table, means for transferring said mill stands between said stand storage area and each said quick change table, and each said quick change table being of a length to span across all of the transferring means of the stands associated with said quick change table.
  • 2. Apparatus according to claim 1, in which said means for transferring mill stands between said stand storage area and each said quick change table includes:a way, intermediate and parallel to each said quick change table and said stand storage area, and at least one controllable mobile transfer device movable along said way and operative for transferring stands delivered to said quick change table to said stand storage area and transferring stands from said stand storage area to said quick change table.
  • 3. Apparatus according to claim 1 wherein each said quick change table is arranged to be translated parallel to the rolling axis on a wheeled system and rails by means of suitable control systems.
  • 4. Apparatus according to claim 1 in which said quick-change table moving means includes means for controllably moving said table between selected linearly spaced positions intermediate said roll pass line and said stand storage area.
  • 5. Apparatus according to claim 1 wherein said means for transferring said mill stands between said roll pass line and each said quick change table include rails as the stands are fitted with wheels suitable to roll on rails.
  • 6. Apparatus according to claim 2 wherein said way is made up of a rail cooperating with wheels integrated on each controllable mobile transfer device.
  • 7. In a mill train for rolling elongated metal product including a plurality of mill stands disposed in-line along a roll pass line, a stand storage area adjacent said roll pass line and a stand preparation area adjacent said stand storage area, apparatus for administering the preparation and transfer of mill stands comprising:said stand storage area including a plurality of stand storage compartments disposed in end-to-end relation along a line parallel to said roll pass line, at least one quick change table, each associated with a plurality of stands of the mill train, extending parallel to said roll pass line and disposed intermediate said roll pass line and said stand storage area, means for moving each said quick change table in opposite linear directions parallel to said roll pass line, means for transferring said mill stands between said roll pass line and each said quick change table, means for transferring said mill stands between said stand storage area and each said quick chance table, and each said quick change table being of a length to span across all of the transferring means of the stands associated with said quick change table, said means for transferring mill stands between said stand storage area and each said quick change table including: a way, intermediate and parallel to each said quick change table and said stand storage area, and at least one controllable mobile transfer device movable along said way and operative for transferring stands delivered to said quick change table to said stand storage area and transferring stands from said stand storage area to said quick change table, wherein said at least one controllable mobile transfer device is a robot.
  • 8. Apparatus according to claim 7 in which said at least one robot includes a frame having wheels enabling movement in a direction parallel to said stand storage area, a base vertically movable with respect to said frame, and a stand operator movable between extended and retracted positions on said base for manipulating a mill stand installed thereon.
  • 9. Apparatus according to claim 8 in which said base mounts spaced, parallel tracks for moving said stand with respect to said base.
  • 10. In a mill train for rolling elongated metal product including a plurality of mill stands disposed in-line along a roll pass line, a stand storage area adjacent said roll pass line and a stand preparation area adjacent said stand storage area, apparatus for administering the preparation and transfer of mill stands comprising:said stand storage area including a plurality of stand storage compartments disposed in end-to-end relation along a line parallel to said roll pass line, at least one quick change table, each associated with a plurality of stands of the mill train, extending parallel to said roll pass line and disposed intermediate said roll pass line and said stand storage area, means for moving each said quick change table in opposite linear directions parallel to said roll pass line, means for transferring said mill stands between said roll pass line and each said quick change table, means for transferring said mill stands between said stand storage area and each said quick change table, and each said quick change table being of a length to span across all of the transferring means of the stands associated with said quick chance table, said means for transferring mill stands between said stand storage area and each said quick change table including: a way, intermediate and parallel to each said quick change table and said stand storage area, and at least one controllable mobile transfer device movable along said way and operative for transferring stands delivered to said quick change table to said stand storage area and transferring stands from said stand storage area to said quick change table, wherein said way communicates with a stand set-up means disposed within said stand preparation area.
  • 11. In a mill train for rolling elongated metal product including a plurality of mill stands disposed in-line along a roll pass line, a stand storage area adjacent said roll pass line and a stand preparation area adjacent said stand storage area, apparatus for administering the preparation and transfer of mill stands comprising:said stand storage area including a plurality of stand storage compartments disposed in end-to-end relation along a line parallel to said roll pass line, at least one quick change table, each associated with a plurality of stands of the mill train, extending parallel to said roll pass line and disposed intermediate said roll pass line and said stand storage area, means for moving each said quick chance table in opposite linear directions parallel to said roll pass line, means for transferring said mill stands between said roll pass line and each said quick change table, means for transferring said mill stands between said stand storage area and each said quick change table, and each said quick change table being of a length to span across all of the transferring means of the stands associated with said quick change table, wherein said plurality of mill stands include a roughing mill section an intermediate mill section and a finishing mill section disposed along said pass line and including a quick change table associated with each of said mill sections.
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Entry
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