Ultra-low temperature forming method for ultra-thin curved part of high-strength aluminum alloy

A method for ultra-low temperature forming an ultra-thin curved part of an aluminum alloy, comprising the following steps:

• (1) providing a sheet with a thickness and made from aluminum alloy, and selecting a cladding with a suitable thickness according to a wrinkle limit of the sheet, so that when the sheet made of solid solution 2195 Al-Li alloy has a thickness of 1 mm and a diameter of 1,500 mm, a corresponding cladding made of pure aluminum and with a thickness of 14 mm and a diameter of 1,500 mm is selected, when the sheet made of 2219-T4 aluminum alloy has a thickness of 4 mm and a diameter of 3,000 mm, a corresponding cladding made of 6061 aluminum alloy and with a thickness of 6 mm and a diameter of 3,000 mm is selected, or when the sheet made of solid solution 2195 Al-Li alloy has a thickness of 1 mm and a diameter of 1,500 mm, a corresponding cladding made of 304 stainless steel and with a thickness of 7 mm and a diameter of 1,500 mm is selected;
• (2) stacking the sheet and the cladding, then putting into a die, and closing a blank holder;
• (3) cooling the sheet to below −160° C. by filling a cavity of a female die with a chilling medium;
• (4) applying a set blank holding force by the blank holder, and enabling a male die to go down to form a curved part which has a wall thickness and an opening diameter with a ratio of less than 3‰ of the wall thickness to the opening diameter;
• and
• (5) opening the die and taking out the formed curved part.