Method of forming parts from sheet steel

Abstract

A method is provided of forming a part from sheet steel. The method comprises the steps of (a) heating the sheet to a temperature at which austenitisation occurs; and (b) forming the sheet between dies into the part, father cooling the formed sheet. There is an additional step between (a) and (b) of applying cooling means to the sheet.

1 . A method of forming a part from sheet steel, the method comprising the steps of:
 (a) heating the sheet to a temperature at which austenitisation occurs; and   (b) forming the sheet between dies into the part, further cooling the formed sheet;   wherein there is an additional step between (a) and (b) of applying cooling to the sheet.   
     
     
         2 . A method according to  claim 1 , wherein the additional step takes place before the heated sheet is placed between the dies. 
     
     
         3 . A method according to  claim 1 , wherein the additional step takes place while the heated sheet is placed between the dies. 
     
     
         4 . A method according to  claim 1 , wherein the cooling comprises a cooling fluid such as a gas, for example air; and/or wherein the cooling fluid comprises a liquid, for example water, the method comprising directing the cooling fluid at the heated sheet. 
     
     
         5 . A method according to  claim 1 , wherein the cooling fluid is directed as a pressurised flow of the fluid. 
     
     
         6 . A method according to  claim 1 , wherein the cooling fluid is directed as a jet and/or is directed as a mist spray. 
     
     
         7 . A method according to  claim 1 , wherein the cooling fluid is directed by controlling the duration, temperature and/or mass flow of the cooling fluid. 
     
     
         8 . A method according to  claim 1 , wherein the cooling comprises cooling plates, for example cool copper plates. 
     
     
         9 . A method according to  claim 1 , wherein the cooling can be achieved by increasing the transfer time with natural air cooling. 
     
     
         10 . A method according to  claim 1 , wherein the additional step comprises directing the cooling fluid at the heated sheet such that the sheet is cooled sufficiently rapidly to avoid the steel entering the bainite phase. 
     
     
         11 . A method according to  claim 1 , wherein the additional step comprises directing the cooling fluid at the heated sheet such that the sheet is cooled at more than 25° C./second on average. 
     
     
         12 . A method according to  claim 1 , wherein the additional step comprises directing the cooling fluid at the heated sheet such that the temperature of the sheet remains above the austenitisation temperature for the steel. 
     
     
         13 . A method according to  claim 1 , wherein the additional step comprises directing the cooling fluid at the heated sheet such that the sheet is cooled to between 500° C. and 600° C. 
     
     
         14 . A method according to  claim 1  and comprising the further step of directing cooling fluid to cool the dies. 
     
     
         15 . A method according to  claim 1  and comprising the further step of directing cooling fluid to clean the dies. 
     
     
         16 . A method according to  claim 1 , comprising the further step of directing cooling fluid to cool and clean the dies in the same step.