EQUALIZATION FURNACE FOR CONTINUOUSLY CAST BILLETS

Abstract: Plant (10) for rolling long products from billets and blooms (30) coming from at least two continuous casting lines (11), each of said at least two lines (11) being provided with a shears (12), said plant comprising a temperature-equalizing furnace (16) disposed downstream of said shears (12) and containing an intake roller conveyor (17) for each of said at least two continuous casting lines (11), a discharge conveyor (18) disposed in an intermediate position between said at least two lines (11), and transversely-moving conveyors (21,26) for transferring said billets or blooms (30) from said intake conveyors (17) to said discharge conveyor (18), said temperature-equalizing furnace (16) further comprising fixed supports (19) located between said intake roller conveyors (17) and said discharge conveyor (18), said fixed supports (19) defining a zone of equalization of the temperature of said blooms and billets (30), and at least some (25) of the rollers belonging to said intake roller conveyor (17) being vertically and transversely displaceable for constituting said discharge conveyor (18).

Description: This invention concerns an equalization furnace for billets and blooms coming from a plurality of continuous casting lines. The equalization furnace is followed by a plant for rolling sections and bars and, more generally, for rolling long products produced from billets or blooms supplied by a plurality of continuous casting lines. Document DE-A-3,525,457 discloses a plant for rolling of metal strips starting from a continuously casted material in the form of a strip. Said material is inserted into a heating or temperature-equalising furnace in order to obtain an optimized strip quality by means of modifying certain parameters. The furnace comprises intake roller conveyors, a discharge roller conveyor and transversal conveyors the structure of which is not defined. Document JP-A-59-35616 discloses a device for charging blooms or billets to be heated into a furnace. Said device picks up said blooms or billets from a roller conveyor by means of a carriage and inserts them transversely inside of the heating furnace. Document JP-A-58-104113 discloses a heating furnace for blooms or billets coming from a continuous casting line or from a cooling bed. The cold blooms are held inside of the furnace for a longer time than the hot blooms. Transversal conveyor comprised inside of the furnace provide to shift the blooms towards a discharge conveyor. Furthermore a plant is known which comprises, downstream of two continuous casting lines positioned side by side, a heated tunnel followed by a lateral traversing conveyor, followed in turn by a discharge conveyor and a temperature-equalising furnace. This plant is very burdensome as regards the space occupied, plant required, machines, maintenance and, above all, as regards energy consumption. It is a purpose of the present invention to avoid the above drawbacks and to provide an economical plant as regards design and construction, maintenance and, above all, energy consumption. This is obtained by a furnace having the features disclosed in claim 1. The dependent claims describe advantageous forms of embodiment of the invention. According to the invention two or more continuous casting lines serve a temperature-equalizing furnace which includes on its median line a discharge roller conveyor. A measurement system which is suitable to read the length of the billet or bloom entering the furnace is provided in cooperation with the inlet of the equalizing furnace. This measurement system is enabled to actuate the shears positioned at the furnace inlet to proceed with shearing when the length of the billet or bloom coincides with the value of the weight of the strip or of the final roll of strip or, in any event, of the material to be obtained. According to the invention, when the billet or bloom has been sheared to size, it is accelerated within the equalizing furnace by variable-speed drive rollers included in the furnace. This acceleration serves to distance the tail of the sheared billet or bloom from the head of the next billet or bloom. The length of the equalizing furnace is normally dimensioned in such a way as to contain a billet or bloom sheared to size, plus a length correponding to the time required for the temperature of the billet or bloom to be made uniformly homogeneous, plus an interspace to be determined between the head and tail of two consecutive billets or blooms. Intermediate supports forming a temperature equalizing and homogenizing zone, are comprised between the intake roller conveyors and the median discharge roller conveyor; the billets or blooms coming from the intake roller conveyors are placed temporarily for their general temperature-equalizing in depth on those intermediate supports. The median discharge roller conveyor can be driven or can consist of idler rollers and may include on its axis a thruster. According to a variant of the invention at least one lateral discharge conveyor is comprised between the shears and furnace so as to remove blooms or billets sheared by the shears whenever the continuous casting line is required to continue working in the event of obstacles or repair work taking place downstream. A toroidal induction heater is included advantageously downstream of the equalizing furnace and enables the temperature of the furnace to be kept 50-120°C lower than that which would otherwise be required, for this temperature is recovered by the toroidal heater. According to another form of embodiment, the furnace plant comprises a heating furnace disposed downstream of the equalizing furnace. The attached figures, which are given as a non-restrictive example, show the following:- Fig.1 gives a plan view of a plant according to the invention; Fig.2 gives a cross section of a furnace suitable to serve the plant of the invention; Fig.3 shows a partial lengthwise section of the furnace of Fig.2. In the figures each of two continuous casting lines 11 of a plant 10 comprises a shears 12 and, in this case, a traversing conveyor 13, which serves a cooling traversing conveyor 14 equipped terminally, for instance, with a stacker 15. The traversing conveyor 13 and its relative cooling traversing conveyor 14 are required when it is decided to continue the continuous casting even when an obstacle occurs downstream. In such a case the shears 12 shears to the required length the bloom or billet coming from the continuous casting lines 11. The continuous casting lines 11 serve intake roller conveyors 17 which accept billets or blooms 30 coming from the continuous casting operations. Each casting line may be equipped with means 48 to measure the length of billets or blooms entering a temperature-equalizing furnace 16; such measurement means 48 controls the shears 12. The rollers of the intake roller conveyors 17 are cooled and driven. Supports 19 positioned crosswise to the intake roller conveyors 17 are comprised within the furnace 16 and are able to support momentarily one or more billets or blooms 30 sheared to the required length by the shears 12 and introduced into a chamber 40 of the furnace 16 along the intake roller conveyors 17 through inlet doors 41. Said supports define a temperature homogenizing and equalizing zone within which the temperature of said billets is homogeneously distributed. A discharge roller conveyor 18 served by discharge rollers 26 is included centrally and comprises at its downstream end a terminal shears 112 located upstream of a rolling train 22. This discharge conveyor 18 cooperates with an outlet 43 for billets and blooms. The intake conveyors 17 may comprise terminal safety outlets 42 when for any reason it is necessary to discharge in a direct line the billets or blooms 30 positioned on the intake conveyors 17. According to the invention the billet or bloom as formed on the continuous casting line 11 and arriving with the required length on the intake conveyor 17 is traversed laterally by an internal traversing means 21, which deposits the billet or bloom 30 first of all on the supports 19 of the temperature homogenizing zone and makes it move forward thereon and places it next on the discharge rollers 26 of a roller support device 20. According to the invention, as the device 20 which supports the discharge rollers 26 is able to traverse them axially and displace them vertically, it is possible to arrange that those rollers 26 themselves move in coordination to take the billet or bloom 30 directly from the supports 19 and to deliver it to the discharge conveyor 18. When the billet or bloom 30 has been placed on the discharge conveyor 18, it is progressively accelerated until it reaches the speed of the first stand of the rolling train 22 so as to be rolled. This acceleration may be imparted by the discharge rollers 26 or by the same in cooperation with an outlet drawing roller unit 47. Discharge of the billet or bloom from the discharge conveyor 18 may also take place by cooperation of a thruster 46, which may be assisted by the outlet drawing roller unit 47. While the billet or bloom 30 is progressively drawn into the rolling operation, the other billets 30 are fed into the furnace 16 and traversed therein to await their turn for processing. Each discharge roller 26 may have a stationary position or be able to move axially and perhaps vertically. If it is movable, it is supported on a support arm 29, which in turn is served by a trolley 31 suitable to move crosswise to the furnace 16 owing to a driven wheel 33 that cooperates in this instance with a rack comprised on the trolley 31. The trolley 31 upholds the support arm 29 by means of a parallelogram of levers 32 which can be moved vertically to the required extent by a jack 44. In this way, when the bloom or billet 30 is discharged by the discharge conveyor 18, it is possible, while waiting to discharge a successive billet or bloom, to lower first the discharge rollers 26 and then to withdraw them momentarily so that they do not become overheated by remaining in the furnace 16 unnecessarily. With this system the discharge rollers 26, moving in coordination, may themselves move to take the blooms or billets 30 from the support 19. The discharge rollers 26 shown are driven at 27 and are cooled by a forced circulation of water through an intake 28. As regards the system of feed by means of the internal traversing means 21, this traversing means 21 comprises an arm 23 able to move in a straight line and vertically and supported on a carriage 37 with rollers, the carriage 37 being moved vertically by shafts 36 supported on a frame 34. In this example the frame 34 is displaced vertically by jacks 35. The frame 34 comprises also a horizontal jack 24 which displaces the movable arm 23 axially by a required value by means of a rod 25. The movable arm 23 comprises a rear lower portion 39 and a front higher portion 38; this conformation makes it possible to take with a normal movement the blooms or billets 30 positioned on the intake conveyors 17 and supports 19 and to make them advance in a required manner. In order to take the bloom or billet 30 located on the intake conveyor 17, the vertical jacks 35 perform a longer travel, thus raising the bloom or billet 30 higher and displacing it onto the support 19 of the temperature-equalizing and homogeneizing zone, where the temperature of said bloom is homogenized. The movable arm 23 then takes the bloom or billet from the support 19 and places it on the discharge conveyor 18, which has been reconstituted in the meantime by return of the roller 26. A scaling means and, in cooperation therewith, the toroidal heater 45 are positioned downstream of the outlet 43 of the discharge conveyor 18.

Claims: Equalization furnace for billets or blooms (30) coming from at least two continuous casting lines (11), each of said at least two lines (11) being provided with a shears (12), said temperature-equalizing furnace (16) being disposed downstream of said shears (12) and containing an intake roller conveyor (17) for each of said at least two continuous casting lines (11), a discharge conveyor (18) disposed in an intermediate position between said at least two lines (11), and transversely-moving conveyors (21,26) for transferring said billets or blooms (30) from said intake conveyors (17) to said discharge conveyor (18), characterized in that said temperature-equalizing furnace (16) further comprises fixed supports (19) located between said intake roller conveyors (17) and said discharge conveyor (18), said fixed supports (19) defining a zone of equalization of the temperature of said blooms and billets (30), and in that at least some (25) of the rollers belonging to said intake roller conveyor (17) are vertically and transversely displaceable for constituting said discharge conveyor (18). Furnace as claimed in Claim 1, in which upstream of each intake roller conveyor (17) is positioned a length measuring means (48) which actuates the respective shears (12) of the continuous casting line (11). Furnace as claimed in Claim 1 or 2, in which a safety outlet (42) is comprised in the equalizing furnace (16) downstream of each of said at least two intake roller conveyors (17) and in cooperation therewith. Furnace as claimed in any claim hereinbefore, in which a traversing conveyor (13-14) for sheared billets or blooms is comprised between the shears (12) of the continuous casting line (11) and the equalizing furnace (16). Furnace as claimed in any claim hereinbefore, in which said rollers (26) forming said discharge conveyor (18) are cooled and/or driven and/or able to be withdrawn momentarily from said equalizing furnace (16). Furnace as claimed in any claim hereinbefore, in which an outlet drawing roller unit (47) is comprised in cooperation with the discharge conveyor (18) at the outlet of the equalizing furnace (16). Furnace as claimed in any claim hereinbefore, in which a thruster (46) is comprised in cooperation with, and upstream on the same axis as, the discharge conveyor (18). Furnace as claimed in any claim hereinbefore, comprising internal traversing means (21) having, each, a movable arm (23) able to be displaced axially (24) and vertically (35-36) in cooperation with said at least two intake roller conveyors (17) and discharge conveyor (18). Furnace as claimed in claim 8, in which said movable arm (23) comprises a rear lower portion (39) and a front higher portion (38). Furnace as claimed in any claim hereinbefore, in which a terminal shears (112) is included between the discharge conveyor (18) and a rolling train (22). Furnace as claimed in any claim hereinbefore, in which a toroidal induction heater (45) is positioned upstream of the rolling train (22). Furnace according to anyone of claims 1 to 10, characterized in that a heating furnace is positioned upstream of the rolling train (22). Furnace as claimed in any claim hereinbefore, in which said equalizing furnace (16) is kept at a temperature up to about 120°C lower than the optimum tamperature for rolling the billet or bloom (30).

Inventors: DI GIUSTO, BRUNO
Applicants: DANIELI & C. OFFICINE MECCANICHE S.P.A.
Application year: 1988
Main classification: C21D9
IPC codes: F27B9, B21B1, C21D9, F27D3