Method and system for forming aluminum alloy blank

Abstract

The present invention relates to a method of forming a 6xxx or 7xxx series Al alloy blank is provided. The method comprises the steps of heating the blank to a solutionization (SHT) temperature, T SHT , for the alloy of the blank at a heating station and keeping the blank at said SHT temperature until SHT is complete, cooling the blank at a cooling station to an intermediate temperature, T ITM , at which the kinetic movement for the alloy in the blank stops and at a cooling rate that is high enough such that re-crystallization in the alloy of the blank does not occur, forming the blank in a forming tool, quenching the formed blank to room temperature, T E , and artificially ageing the formed and quenched blank in an ageing station. The present invention further relates to a 6xxx or 7xxx series Al alloy blank forming system ( 1, 3 ).

1 . A method of forming a 6xxx or 7xxx series Al alloy blank, wherein the method comprises the steps of:
 heating the blank to a solutionization (SHT) temperature (T SHT ) for the alloy of the blank at a heating station and keeping the blank at said SHT temperature until SHT is complete,   cooling the blank at a cooling station to an intermediate temperature (T ITM ) and at a cooling rate that is high enough such that re-crystallization in the alloy of the blank does not occur wherein for a 6xxx series Al alloy blank the intermediate temperature is between 300-350° C. and the cooling rate is at least 30 K/s, and for a 7xxx series Al alloy blank the intermediate temperature is between 400-420° C. and the cooling rate is at least 50 K/s,   forming the blank in a forming tool,   quenching ( 108 ) the formed blank ( 2 ′) to room temperature (TE),   pre-ageing the formed and quenched blank in a pre-ageing station within one hour of the quenching of the formed blank for a 6xxx series Al alloy blank and within 30 minutes of the quenching of the formed blank for a 7xxx series alloy blank, in which pre-ageing the formed and quenched blank is heated to an ageing temperature (T A ), kept at the ageing temperature during a time period, and cooled to room temperature.   
     
     
         2 . (canceled) 
     
     
         3 . The method according to  claim 1 , wherein the forming tool is preheated to the intermediate temperature (T ITM ). 
     
     
         4 . The method according to  claim 1 , wherein the blank is kept at the intermediate temperature (T ITM ) during the forming in the forming tool. 
     
     
         5 . The method according to  claim 1 , wherein the forming is performed in a first forming tool and the quenching is performed in a second forming tool. 
     
     
         6 . A 6xxx or 7xxx series Al alloy blank forming system comprising,
 a heating station configured to heat a blank to its SHT temperature (T SHT ),   a cooling station configured to cool the blank to an intermediate temperature (T ITM ) and at a cooling rate that is high enough such that re-crystallization in the alloy of the blank does not occur, wherein for a 6xxx series Al alloy blank the intermediate temperature is between 300-350° C. and the cooling rate is at least 30 K/s, and for a 7xxx series Al alloy blank the intermediate temperature is between 400-420° C. and the cooling rate is at least 50 K/s   at least one forming tool configured to form and quench the blank, and   a pre-ageing station configured to provide an artificial pre-ageing process to the formed and quenched blank, wherein the pre-ageing station is arranged relative to the forming tool such that the pre-ageing can take place within one hour of the quenching of the formed blank for a 6xxx series Al alloy blank and within 30 minutes of the quenching of the formed blank for a 7xxx series alloy blank, and wherein the pre-ageing station is configured to heat the formed and quenched blank to an ageing temperature (T A ), keep it at the ageing temperature during a time period, and cool it to room temperature.   
     
     
         7 . (canceled) 
     
     
         8 . The system according to  claim 6 , wherein the forming tool is configured to be preheated to the intermediate temperature prior to forming the blank. 
     
     
         9 . The system according to  claim 5 , wherein the forming tool is configured to keep the blank at the intermediate temperature (T ITM ) during the forming in the forming tool. 
     
     
         10 . The system according to  claim 5 , wherein the system comprises a first forming tool configured to form the blank, and a second forming tool configured to quench the blank.