Forming method

Abstract

A method of shear forming a component comprises the steps of: (i) providing a pre-formed metallic sheet blank, the sheet blank having a first surface and an opposite second surface, the perpendicular separation between the first surface and the second surface defining a thickness of the sheet blank; (ii) applying a surface modification process to the first surface of the sheet blank to reduce a surface roughness of the first surface to a first predetermined roughness value; (iii) positioning the second surface of the sheet blank against a mandrel; and (iv) applying a roller to the first surface of the sheet blank in a shear forming operation to form the sheet blank into the component.

What is claimed is: 
     
         1 . A method of shear forming a component from a pre-formed metallic sheet blank, the sheet blank having a first surface and an opposite second surface, the perpendicular separation between the first surface and the second surface defining a thickness of the sheet blank, the method comprising the steps of:
 (i) providing the metallic sheet blank;   (ii) applying a surface modification process to the first surface of the sheet blank to reduce a surface roughness of the first surface to a first predetermined roughness value;   (iii) positioning the second surface of the sheet blank against a mandrel; and   (iv) applying a roller to the first surface of the sheet blank in a shear forming operation to form the sheet blank into the component.   
     
     
         2 . The method as claimed in  claim 1 , wherein the metallic sheet blank is formed by a rolling process, and step (ii) comprises the step of:
 (ii)′ applying a surface modification process to the first surface of the sheet blank to reduce a surface roughness of the first surface to a first predetermined roughness value, the second surface of the sheet blank remaining in an as-rolled condition.   
     
     
         3 . The method as claimed in  claim 1 , wherein step (ii) comprises the step of:
 (ii)″ applying a surface modification process to the first surface of the sheet blank to reduce a surface roughness of the first surface to a first predetermined roughness value, and applying a surface modification process to the second surface of the sheet blank to reduce a surface roughness of the second surface to a second predetermined roughness value, the second predetermined roughness value being greater than the first predetermined roughness value.   
     
     
         4 . The method as claimed in  claim 1 , wherein the surface modification process is selected from the group consisting of abrasive grinding, electrochemical grinding, electrolytic etching, electro-polishing, shot blasting, grit blasting, acid pickling, molten salt bath treatment, and etching. 
     
     
         5 . The method as claimed in  claim 1 , wherein the sheet blank is formed from a material selected from the group comprising titanium alloys nickel-cobalt-based superalloys, stainless steels, and aluminium alloys. 
     
     
         6 . The method as claimed in  claim 1 , wherein the first surface of the sheet blank has a first predetermined roughness value (Ra) of less than 3.0 μm. 
     
     
         7 . The method as claimed in  claim 6 , wherein the first surface of the sheet blank has a first predetermined roughness value (Ra) of less than 2.0 μm. 
     
     
         8 . The method as claimed in  claim 6 , wherein the first surface of the sheet blank has a first predetermined roughness value (Ra) of less than 1.0 μm. 
     
     
         9 . A computer program that, when read by a computer, causes performance of the method as claimed in  claim 1 . 
     
     
         10 . A non-transitory computer readable storage medium comprising computer readable instructions that, when read by a computer, causes performance of the method as claimed in  claim 1 . 
     
     
         11 . A signal comprising computer readable instructions that, when read by a computer, causes performance of the method as claimed in  claim 1 .