The present invention relates to a method and an apparatus for the rapid delivery of metallic plates made from heavy plate from a rolling mill.
A plate which is made from heavy plate is simply referred to herein as a plate. It is understood in this application to mean a metallic plate having a thickness of between 8 mm and 250 mm, a width>900 mm and a length≧3 m (cf. Document 570, “Grobblech—Herstellung and Anwendung”, Steel Information Center, Düsseldorf, 1st Edition 2001).
The invention relates to a method for delivery of metallic plates, preferably made of steel, from a rolling mill, preferably a hot-rolling mill or a combined casting and rolling plant.
The invention further relates to an apparatus for rapid delivery of steel plates from a hot-rolling mill.
A continuous casting plant of a combined casting and rolling plant is normally used to produce a continuous (i.e. endless) slab. The continuous (endless) slab itself or a slab which is cut therefrom is then subjected to reshaping in at least one rolling stand of a roughing mill train, and a high reduction factor is applied in this case. The roughed continuous slab (also called a transfer bar) or the roughed slab is then heated in a reheating furnace and descaled in a descaling device. A subsequent multistand finishing mill train which comprises at least five, and optionally up to seven, rolling stands generates steel strips of various thicknesses depending on the number of rolling stands in use and the reduction factors that have been set. Finally, these strips are cooled to the required temperature in a cooling zone and are then wound into steel coils in at least two coiler devices alternately. The steel strip is cut to length as appropriate before winding, if necessary.
Using this known process for the production of steel coils, it is possible to produce hot strip having a thickness of 0.6 mm to 25 mm and even up to 30 mm in some circumstances (in the case of materials having limited width and low resistance).
These coils can be processed subsequently in a separate work stage and/or in a separate apparatus to form plates (so-called sheets having a thickness of less than 3 mm or heavy plates having a thickness of 3 mm to 25 mm, optionally up to 30 mm).
EP 1909979 B1 describes a combined casting and rolling plant for the production of plates having thicknesses of up to 100 mm and widths of up to 4000 mm. The slab produced in the continuous casting process undergoes liquid core reduction (LCR) in the continuous casting machine. Reduction of the slab then takes place in one or more rolling stands of a mill train. The strand is then cooled and cut to the desired plate length. It also describes the need for a descaling apparatus upstream of the rolling stands and an apparatus for thermomechanical treatment of special steel goods by means of an intermediate cooling stage between the reducing stands.
DE 102010063279 A1 describes a CSP plant for the production of thick tubular goods and thin strip. Once produced, the thin strips or thick tubular goods are wound into steel coils on coiling machines in the CSP plant. These coils can be postprocessed in separate plants to produce plates.
A further known production method for plates is provided in the form of plate mills. These rolling mills are designed to roll the feedstock or slabs longitudinally and/or transversely in order to produce plates of various thicknesses, widths and lengths therefrom. The plate mills have a reheating furnace, one or two rolling stands, a straightening machine, shears and locations for annealing, cooling and storage. The rolling stands are usually operated in reversing mode. Also optionally available are turntables for rotating the plates for the rolling process, Steckel furnaces, and upsetting devices for setting the correct widths. This method is primarily used for thicker and/or wider plates. Production of limited-width hot strip is uneconomical and/or impossible.
Plates can also be produced and/or postprocessed on a cut-to-length line. In this case, the wound coils are unwound again, straightened, cut to length, processed to form plates and stacked. However, these apparatuses only allow the production of plates having a thickness of up to approximately 16 mm.
WO 2009/121678 A1 describes a delivery device for a combined casting and rolling plant. The device allows continuous casting plant of the combined casting and rolling plant to continue running in an emergency situation. In this case, cut intermediate product sections having a length of 8 m to 14 m are transferred out of the plant. When using the large plate lengths specified, it is possible by accelerating the cut intermediate product sections to produce gaps of sufficient length between the individual sections that collisions between the sections are prevented. The speeds which are used for these intermediate products are still relatively low, allowing the intermediate product sections to be transported out of the plant.
One object of this invention is to specify a method and an apparatus for the delivery of plates from a combined casting and rolling plant, wherein even relatively short plates (e.g. having a length of 3 to 8 m) can be transferred out of the plant and stored reliably at high speed and using short cycle times.
A further object of this invention is to extend the product range of a combined casting and rolling plant such that, in addition to the possibility described above in respect of the production of steel coils in the combined casting and rolling plant, it is also possible to manufacture plates of various thickness and length. In this case, it is preferably possible to set the plant parameters, e.g. the number of active rolling stands and their reduction factors, such that plates having thicknesses of at least 8 mm to 25 mm, preferably up to 40 mm, widths of 900 mm to 2100 mm, and lengths of 3 m to 18 m can be produced inline (i.e. in the combined casting and rolling plant itself). In addition to tubular goods, it is preferably possible to produce other goods in this case. During the manufacture of plates, it is preferably possible for the material (e.g. which is produced continuously in endless operation) to be cut to length at a suitable location. Finally, it is preferably possible for the plates of predetermined length to be transferred out of the plant and stored, in order that production of the next material can continue unimpeded. It is preferably possible to reconfigure the outward transfer and storage device easily and quickly for different plate lengths.
This object is achieved by the method cited in the introduction, comprising the following method steps:
After an e.g. endlessly produced strand of hot strip has been cut to length, whereby a first plate is separated from the strand of undefined length, the first plate is transported on the roller table in the direction of transport. The first plate is preferably accelerated in the direction of transport in this case, such that a gap is formed between the strand and the first plate. After the first plate has reached a predefined position on the roller table, the first plate is stored on the roller table. A second plate is then separated from the strand, and the second plate is transported on the roller table in the direction of transport. After the second plate has reached a predefined position on the roller table, the second plate is stored in the direction of transport in front of the first plate on the roller table. Therefore at least two plates are stored in-line on the roller table. The first and the second plate are then delivered from the roller table into a storage location, wherein the delivery is preferably effected transversely relative to the direction of transport. Alternatively, the plates could also be delivered in a vertical direction (e.g. above or below the roller table). The delivery which takes place transversely relative to the direction of transport is also called a lateral transfer, and the device for this purpose is referred to as a lateral conveyor.
As a result of storing a plurality of plates in-line on the roller table and delivering a plurality of plates concurrently, it is also possible reliably to deliver considerably shorter plates while maintaining the same cycle time of the delivery device.
The concurrent delivery of a plurality of plates from the roller table can essentially take place in two ways:
A combination is also conceivable, e.g. a plurality of lateral conveyors each delivering a plurality of plates (e.g. two lateral conveyors delivering two plates each).
During the production of particularly short plates, it is advantageous to transport at least a third plate on the roller table in the direction of transport, and to store the third plate in the direction of transport in front of the second plate on the roller table. The first, second and third plates are then delivered concurrently. As a result, either the minimal plate length is further reduced for a given cycle time, or the cycle time is increased for a given plate length.
Owing to the space conditions in a rolling mill, it is usually advantageous for the delivery of the plates to take place transversely relative to the direction of transport.
A lateral conveyor advantageously performs the following steps during the delivery:
Alternatively, the delivery can also be effected by means of the following method steps:
The stacking of a plurality of plates on a storage location is particularly easy if the storage location is lowered by at least the plate thickness after storing the at least one plate.
In a rolling mill, the plates are separated from a strip/strand, i.e. cut to length, before being transported on the roller table in the direction of transport.
The object cited in the introduction is likewise achieved by means of an apparatus for the rapid delivery of steel plates from a hot-rolling mill, comprising
The delivery device comprising a plurality of lateral conveyors, for the synchronous delivery of at least one plate each, includes a synchronization device (e.g. an active connection between the control/regulating devices (cf. “selsyn system”) of the lateral conveyors, or a mechanical connection between the lateral conveyors) for synchronizing the lateral conveyors.
In a simple and robust embodiment variant, the means for storing the plate on the roller table comprises a limit stop and preferably an actuator (e.g. a hydraulic, pneumatic or electric actuator) for moving the limit stop into and out of the transport path of the plate on the roller table.
According to an alternative and particularly simple embodiment variant, the means for storing takes the form of a table roller which can be braked.
Collisions between the plates can be prevented if the roller table has a plurality of means for storing, these being arranged one behind the other in the direction of transport.
A simple lateral conveyor has a lifting rail, a lift actuator for raising the lifting rail, a traversing carriage for moving the plate transversely relative to the direction of transport, and a movement actuator for moving the traversing carriage on the lifting rail.
In an appropriate configuration, the lifting rail has a plurality of arms, at least one table roller being arranged between two arms in the starting position. In the context of this application, the starting position is understood to be any position which the lateral conveyor occupies immediately before the plates are delivered transversely relative to the direction of transport.
A further simple lateral conveyor has a gripper for clamping a plate and a swiveling unit for swiveling the plate about an axis of rotation which is oriented in the direction of transport.
A simple storage location takes the form of a variable-height storage table, which has an actuator for varying the height of the storage table.
Since the plate is preferably cut after the final stand of the finishing train and before the plate enters the cooling device, and the plate is accelerated on the roller table after cutting in order to create a gap between the continuously produced hot strip and the plate, the plate will exhibit a variable transport speed according to the temporal profile of the acceleration. In order nonetheless to achieve uniform cooling of the plate in the cooling section, the cooling section comprises
The corresponding cooling section comprises
The adjustment device takes the form of a control device or regulating device, for example. In the case of a regulating device, the desired volume of coolant is calculated as a function of the speed and the actual volume of coolant is set in a regulated manner such that the difference between the desired volume of coolant and the actual volume of coolant is as small as possible.
In an advantageous configuration, the speed is detected iteratively as the plate passes through the cooling section and the cooling section comprises a plurality of cooling zones (each of which has at least one cooling nozzle). The cooling of the plate can therefore be set very precisely, even in the case of transient speed or acceleration profiles. The speed in a section can be determined by means of position detectors which determine the throughput time of the plate between two positions, for example, such that the speed can easily be determined when the distance between two detectors is known.
Alternatively, the speed can however also be determined by other means, e.g. measuring the speed of the table rollers, laser doppler anemometry, etc.
Further advantages and features of the present invention are derived from the description of exemplary embodiments, which are not restrictive, and the following figures in which:
The production of plates of various thickness, width, length and material takes place in a combined casting and rolling plant of the type known as Arvedi ESP (Endless Strip Production) as shown in
Liquid steel is cast in a continuous casting plant 1 to form a continuous thin slab having a thickness of 70 mm to 125 mm and width of 900 mm to 2100 mm. The continuous thin slab has a liquid core and undergoes so-called “liquid core reduction” (LCR) in the curved strand guider 2 of the continuous casting plant 1.
After leaving the continuous casting plant, the endlessly produced continuous thin slab is roughed with a high reduction factor by at least one and at most four rolling stands in a roughing mill train 3. After the roughed continuous slab or so-called transfer bar 17 has passed uncut through flying shears 4, it is reheated in an induction furnace 5 and descaled in a subsequent descaling device 6. After descaling, the roughed transfer bar is finish-rolled in a multistand finishing train 7 comprising at least four and preferably at least five rolling stands 7a to 7d to form a finished strip 18 or plate strand (
After the hot strip has been finish-rolled in the final rolling stand 7d, the finished strip 18, which is still endless at this point, is cut into plate lengths of 3 m to 18 m by means of shears 8. As illustrated in
Immediately after a plate is cut off from the endless finished strip 18, the plate is accelerated in the direction of transport T on the roller table 9 by a plurality of driven table rollers 9a, in order to generate as much intermediate space as possible between the finished strip 18 and the cut off plate. This intermediate space is determined by the length of the plate, the acceleration of the plate and the acceleration time. It applies generally that the shorter the plates, the shorter the cycle time for delivery of the plates and the smaller the intermediate spaces between the plates.
By way of example, Table 1 below shows the relationship between the plate length L, the cutting order t assuming a strip speed of 0.8 m/s, and an intermediate space between plates of Δs assuming a plate acceleration of a=1 m/s2 to v=3 m/s. Furthermore, the final column shows the sequence time tSequ (also known as cycle time) for the lateral conveyor when n plates are delivered concurrently.
Table 1: Cutting order and sequence time
In addition to the advantages described above, it is advantageous that the plates produced in the endless process are only cut to length after the final rolling stand 7d, since the properties of the material (straightness and flatness of the head and tail ends of the plates) then remain approximately constant and no further processing steps are required in the production line.
By comparison, when using methods according to the prior art, in which the transfer bar 17 is cut to length upstream of the finishing mill train 7 or slabs that are already of limited length are used in a mill train 3, 7, the contour of the head and tail ends of the plates is deformed or vertically warped as a result of the constant threading into and out of every individual reducing stand, and therefore the stacking or subsequent processing of such plates can only be performed effectively if provision is made for an additional trimming step (each trimming step produces scrap metal and reduces the productivity of the plant) or straightening operation.
Once it has been cut off, the plate is cooled in a cooling section 10. The variable speed of the plate, caused by the acceleration, is taken into consideration in the cooling section 10 by dynamically regulating the cooling rates. For this purpose, the position of the head end of the plate is tracked within the cooling section. This ensures a uniform surface temperature of the plate (including the head end and tail end of the plate). The tracking of the plate within the cooling section can be effected by means of a plurality of inductive detectors which are situated above or below the roller table and register the passage of a plate. Depending on the speed of the plate on the roller table within the cooling section, the plurality of cooling nozzles, which are arranged one behind the other in the direction of transport and can be set independently of each other, are set in such a way that all longitudinal sections of the plate are sprayed with the same amount of water.
After the cooling section 10, the plates that have been produced are transported by means of the roller table 13 and past the coiler units 11a, 11b to the delivery device 14. For this purpose, the strip arresting device shown in
The plates are transported via the subsequent roller table 13 to the delivery device 14. So-called adjustable lateral guides which can be hydraulically or electromechanically adapted to the plate width are provided in this region for the purpose of presetting the plate position transversely relative to the direction of transport T. A straightening machine may also be arranged in this region for the purpose of rectifying possible transverse warping or curvature of the plates.
The delivery device 14 is designed in such a way that the continuously cast strand from the continuous casting machine 1 or the finished strip 18 which is continuously hot-rolled in the finishing mill train 7 can be supplied without interruption, transferred out of the hot-rolling mill and stacked without disrupting the endless operation of the combined casting and rolling plant or influencing the production speed. This requirement cannot be satisfied using apparatuses according to the prior art, particularly in the case of short plates, since the cycle times tSequ for the delivery device 14 are too short. By contrast, this requirement is satisfied by the invention, specifically because a plurality of plates stored one behind the other on the roller table are delivered concurrently, thereby increasing the cycle time.
The delivery device 14 comprises a roller table 13 on which plates 21, 22 can be transported in the direction of transport T, means in the form of the rear limit stop 26a for storing a first plate 21 and means in the form of the forward limit stop 26b for storing a second plate 22 on the roller table 13, and a lateral conveyor 15 for the concurrent delivery of two plates 21, 22 transversely relative to the direction of transport T onto a storage location 24. The roller table 13 has a plurality of driven 9a table rollers 31; non-driven table rollers may also be present. According to the illustration in
Before the actual delivery of the plates 21, 22 in the delivery device 14, the endless finished strip 18 is cut to length by the shears 8 after the final stand 7d of the finishing mill train 7 (see
After the first plate 21 has passed the coiler devices 11a, 11b and the open trap 12, the first plate 21 on the roller table 13, also known as a connecting roller table, enters the delivery device 14.
In the delivery device 14 itself, the first plate 21 is transported onward in the direction of transport T until it is stored on the roller table 13 by a means for storing the first plate, said means taking the form of a rear limit stop 26a. The limit stop 26a is swiveled into the transport path of the first plate 21 by an actuator (not shown), thereby blocking the transport path. The first plate 21 rests on at least two table rollers 31.
According to an alternative embodiment variant, the means for storing takes the form of a light barrier or camera which has an active connection to a plurality of driven table rollers 31. As soon as a plate reaches a predetermined storage position, the table rollers 31 are braked such that the plate on the roller table is stored.
Subsequently or meanwhile, the shears 8 cut off a second plate 22 from the endless finished strip 18. The second plate 22 is likewise transported on the roller table 9 in the direction of transport T to the delivery device 14. Before the second plate 22 on the roller table 13 reaches the storage position, a forward limit stop 26b is swiveled into the transport path, thereby causing the second plate 22 to be stored in the direction of transport T in front of the first plate 21 on the roller table 13. The second plate 22 likewise rests on at least two table rollers 31.
As an alternative to providing a plurality of limit stops 26a, 26b, the delivery device 14 may also have only a single limit stop (e.g. the rear limit stop 26a), in which case the second plate 22 would collide with the first plate 21 and/or a third plate (not shown) would collide with a second plate 22 if applicable. In the case of relatively thin plates in particular, it is nonetheless advantageous to provide a plurality of limit stops since it is thereby possible to prevent distortion of the plates due to collisions.
In order to increase the cycle time tSequ for the lateral conveyor 15 even in the case of relatively short plates, provision is essentially made for at least two plates 21, 22 to be delivered concurrently. This can be effected either by a single lateral conveyor 15 which delivers a plurality of plates concurrently, or by a plurality of lateral conveyors that work concurrently (see the lateral conveyors 15, 15′ in part A) of
The lateral conveyor 15 itself is illustrated in
The movement in the illustrated case is effected by means of a linear motor 29a, e.g. an electric linear drive, a hydraulic or pneumatic cylinder, etc. The traversing carriage 29 is supported via wheels on a lifting rail 27 which can be raised and lowered by one or more lifting cylinders 28. The lifting rail 27 is supported relative to the fixed supporting structure via two swiveling levers, wherein the right-hand swiveling lever illustrated in
The lifting of the first and the second plates 21, 22 off the table rollers 31 of the roller table 13 is illustrated in
After being lifted off, the plates 21, 22 are moved towards the storage location 24 by the traversing carriage 29 in the direction of movement V. The movement is effected by the extension of one or more movement actuators 29a (see
The situation after the movement of the plates 21, 22 in the direction of movement V is illustrated in
In
Once the plates 21, 22 have been clamped by the gripper 25, the swiveling unit 32 is swiveled through approximately 180°, thereby moving the plates from the position illustrated on the left to that illustrated on the right. The plates 21,22 are then released by the gripper 25 and stored on the storage table 33. After storage of the plates, the swiveling unit 32 is swiveled back to the starting position, such that a plurality of plates can be delivered again.
Parts A) to F) of
In
Two plates are delivered concurrently in
Finally,
Although the invention is illustrated and described in detail with reference to the preferred exemplary embodiments, the invention is not restricted by the examples disclosed herein, and other variations can be derived therefrom by a person skilled in the art without thereby departing from the scope of the invention.
Number | Date | Country | Kind |
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A50339/2013 | May 2013 | AT | national |
The present application is a 35 U.S.C. §§371 national phase conversion of PCT/EP2014/056560, filed Apr. 2, 2014, which claims priority of Austrian Patent Application No. A50339/2013, filed May 21, 2013, the contents of which are incorporated by reference herein. The PCT International Application was published in the German language.
Filing Document | Filing Date | Country | Kind |
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PCT/EP2014/056560 | 4/2/2014 | WO | 00 |