Lubricant for elevated temperature forming
AssigneeGM Global Technology Operations LLC
InventorsPaul E. Krajewski, Yang T. Cheng
Life of this patent
Estimating the term…
Abstract
The hot stretch forming of sheet metal alloys, such as highly deformable aluminum alloy materials, is improved by using a lubricant comprising bismuth between the forming tool and the engaged surface of the sheet metal. A precursor of bismuth, such as bismuth subsalicylate, may be dispersed in a liquid and applied to the sheet metal before the sheet is heated to its forming temperature. Other lubricants such as boron nitride may be combined with the bismuth precursor. The precursor compound is decomposed to bismuth (or bismuth and carbon in the case of bismuth subsalicylate) which lubricates contact between the surface(s) of the sheet and the forming tool during forming and removal of the formed part from the tool.
Claims8
A method of forming sheet metal alloys at elevated temperatures, the method comprising:
- suspending particles of bismuth subsalicylate in a liquid;
- applying a coating of the suspension to at least a first side of a metal alloy sheet, the sheet having an opposing side;
- heating the metal alloy sheet with the bismuth subsalicylate particles coating to a forming temperature, the bismuth subsalicylate decomposing to a lubricant comprising bismuth prior to or during forming of the metal alloy sheet;
- and
- forming the sheet into a desired configuration by stretching the first side of the sheet with the lubricant into conformance with a heated forming surface of a forming tool.
Dependencies are inferred from the claim text.