METHOD TO PREHEAT BILLETS WITH A SAVING OF ENERGY

Abstract: Method to preheat billets, blooms or slabs, before rolling (14), as they arrive from a store of cold charges (10) or from continuous casting (11), such method involving a preheating furnace (12) and a heating furnace (13), the preheating (12) and heating (13) furnaces being connected in coordination, in which method: - material (15) arriving from the store of cold charges (10) passes through the preheating furnace (12) and the heating furnace (13), - material (17) arriving from the continuous casting (11) but momentarily halted due to work in progress in the rolling plant (14) is transiently stored in the preheating furnace (12) and is then passed through the heating furnace (13) when such work has ended and rolling can restart, - and material (18) coming from the continuous casting (11) passes through the heating furnace (13) before reaching the rolling process (14) during a normal cycle.

Description: This invention concerns a method to preheat and heat billets, blooms or slabs so as to optimise their temperature for a successive rolling operation. The invention provides for the overall form of the method to lead to a saving of energy by a reduction of energy consumption. The invention is applied correctly in cooperation with a continuous casting plant. The known art envisages that billets, blooms and slabs coming from a continuous casting plant are heated before passing on to the rolling cycle. Moreover, the known art visualises that the cold charges forming a buffer stock are heated before moving to the rolling cycle. The known art envisages also that during stoppages of rolling for any reason the material leaving the continuous casting is parked so as to become a cold charge. JP-A-57 202907 discloses that billets and blooms are occasionally switched momentarily from the normal path which they follow before reaching the pre-heating furnace, and are deposited in an auxiliary heating furnace. US-A-4,311,454 provides for a traditional system to transfer blooms and billets, the system being improved by an additional movement imparted to the blooms and billets so as to make them pass from a pre-heating furnace to a heating furnace with a change in their axis of feed. DE-A-3.310.867 discloses a multiple furnace to heat billets. JP-A-5 820301 provides a multiple furnace to heat billets. JP-A-58 204128 provides a unit consisting of a heating furnace and pre-heating furnace positioned in parallel. JP-A-59 190327 also provides a unit consisting of a heating furnace and a pre-heating furnace, separate from each other but positioned in working sequence. The present applicant has established that these systems of handling billets, blooms and slabs entail a considerable waste of energy with high consumption and great waste. He has therefore set himself the problem of determining a method for handling these products which is such that the heating operations take place in an optimised manner from the point of view of an energy balance as well. This invention is set forth and characterized in the attached claim. According to the invention the material to be rolled can come from a cold charge store or buffer store and be parked temporarily to await re-approval or maintenance of the rolling plant or can pass continuously through directly from the continuous casting. According to the invention a preheating and holding furnace and a heating furnace are provided. These two furnaces are positioned in series and connected at position 16 and cooperate with each other in enabling the material to pass through correctly. According to the invention it is possible to envisage one single furnace divided into two diversely specialized zones. The attached figure shows diagrammatically the preferred embodiment employed to illustrate the invention. According to the invention the material forming a cold charge 15 and coming from a cold charge store 10 enters a preheating furnace 12 and passes on to a heating furnace 13 and then to a rolling line. Material 17 consisting of product arriving from continuous casting 11 and retained in a holding phase, since the rolling plant 14 is being maintained or having the rolling groove changed, is parked provisionally in the preheating furnace 12 before being moved to the heating furnace 13 and then to the rolling process 14. Likewise, material 18 coming from continuous casting 11 goes directly to the rolling process 14 after being heated in the heating furnace 13. The invention therefore provides for the material coming from continuous casting and waiting to pass to the temporarily halted rolling plant to be parked transiently in the preheating furnace 12.

Claims: 1. Method to pre-heat billets, blooms or slabs, before rolling (14), as they arrive from a store of cold charges (10) or from continuous casting (11), the method involving a preheating furnace (12) and a heating furnace (13) whereby the pre-heating (12) and heating (13) furnaces are positioned side by side and are connected in a coordinated manner, and whereby: material (15) arriving from the store of cold charges (10) passes through the pre-heating furnace (12) and through the heating furnace (13), material (17) arriving from the continuous casting (11) but momentarily halted due to work in progress in the rolling plant (14) is stored transiently in the pre-heating furnace (12) and is then passed through the heating furnace (13) when such work has ended and rolling can re-start, and material (18) coming from the continuous casting (11) passes through the heating furnace (13) before reaching the rolling process (14) during a normal cycle, the method been characterized in that the furnaces are separated and the material (15-17) passes from the pre-heating furnace (12) to the heating furnace (13) by being displaced axially.

Inventors: NONINI, GEREMIA
Applicants: DANIELI & C. OFFICINE MECCANICHE S.P.A.
Application year: 1987
Main classification: C21D9
IPC codes: B21B1, C21D9