Method and apparatus for casting, hot rolling and annealing non-heat treatable aluminum alloys

Abstract

This invention provides a method and apparatus for casting, hot rolling and annealing of non-heat treatable aluminum alloys which comprises continuously casting, hot rolling, and, in-line with the hot rolling line, inductively heating the aluminum sheet. The induction heating system uses a feedback control to assure that the aluminum alloy is heated to the proper temperature based on one or a number of process variables, such as hot rolling exit temperature, hot rolled product exit rate in terms of speed and product dimensions, and sheet temperature at the exit of the induction heater. Variations in the induction heating temperature can be tolerated in the product without deviating from target mechanical properties.

What is claimed is:  
     
         1 . In a method of casting, hot rolling and annealing non-heat treatable aluminum alloys, whereby a cast product is directly hot rolled to form a hot-rolled product, and the hot-rolled product is directly annealed to form an annealed product, the improvement comprising: 
 a) inductively heating the hot-rolled product from an elevated temperature caused by the latent heat in the hot-rolled product to a final annealing temperature to form the final annealed product; and    b) controlling the inductive heating using a feedback control based on at least one heating parameter and the elevated temperature.    
     
     
         2 . The method of    claim 1   , comprising the step of protecting the surface of the final annealed product after the inductive heating step and then coiling the final annealed product to form a coiled product.  
     
     
         3 . The method of    claim 2   , wherein the protecting step comprises one of oiling the surface of the final annealed product with a protective oil or a forming lubricant used in subsequent processing of the sheet or interleaving a protective material between surfaces of the final annealed product during the coiling step.  
     
     
         4 . The method of    claim 1   , comprising the step of coiling the final annealed product.  
     
     
         5 . The method of    claim 1   , wherein the elevated temperature ranges between about 400° F. and 600° F. and the final annealing temperature ranges between about 650° F. and 1100° F.  
     
     
         6 . The method of    claim 1   , wherein the casting is belt casting, block casting or roll casting.  
     
     
         7 . The method of    claim 1   , wherein the feedback control uses the elevated temperature hot rolled product and one or more measures of the temperature of the final annealed product after induction heating is completed, the gauge and width of hot rolled product being inductively heated, and the speed of the hot rolled product as it travels through the induction heater.  
     
     
         8 . The method of    claim 1   , wherein the inductively heated product is cooled by quenching using one of air, water, or a combination thereof or is cooled by natural air cooling.  
     
     
         9 . The method of    claim 1   , comprising one of accumulating the hot rolled product prior to the induction heating step and accumulating the inductively heated product and then coiling the accumulated product.  
     
     
         10 . In an apparatus including a caster, hot rolling mill, and an induction annealing furnace for casting, direct hot rolling and annealing non-heat treatable aluminum alloys, the improvement comprising: 
 a) an inductive heating device positioned directly downstream of the hot rolling mill for annealing the hot-rolled product from an elevated temperature caused by latent heat in the hot-rolled product to a final annealing temperature to form a final annealed product; and    b) a cooling device downstream of the induction heating device for quenching.    
     
     
         11 . The apparatus of    claim 10   , wherein the cooling device includes a quenching device and a coiling device to coil the final annealed product after quenching.  
     
     
         12 . The apparatus of    claim 10   , comprising an oiler positioned downstream of the quenching device and upstream of the coiling device.  
     
     
         13 . The apparatus of    claim 10   , wherein the induction heating device is a transverse flux induction heating device.  
     
     
         14 . The apparatus of    claim 11   , wherein the quenching device uses one or more of air and water.  
     
     
         15 . The apparatus of    claim 10   , comprising an accumulator positioned between the hot rolling mill and the induction heating device.  
     
     
         16 . The apparatus of    claim 10   , comprising an accumulator positioned between the induction heating device and the coiling device.  
     
     
         17 . The apparatus of    claim 16   , comprising another accumulator positioned between the hot rolling mill and the induction heating device.  
     
     
         18 . The apparatus of    claim 10   , wherein the coiling device which allows the coiled final anneal product to be air cooled from the annealing temperature in coil form.