Deep:drawn parts made from annealed aluminium or its alloys - where cold stretching of sheet of strip prior to deep drawing increases proof stress without impairing drawability

摘要

Directly before stamping or drawing, the annealed material is subjected to a cold working treatment causing a 2-5% increase in the length of the sheet. Due to this treatment, pressed or drawn parts made from the material possess increased mechanical strength. The initial material is pref. sheet or strip, which is subjected to repeated alternate bending causing the stretching required. The cold work is pref. obtd. by feeding the sheet or strip along an S-shaped path formed by two rolls, the second roll possessing a larger dia. than the first roll so the strip is stretched. For a given prod., the thickness of sheet used in its mfr. may be reduced but the same mechanical strength is achieved; in this way, less material is required. Alternatively, when the same thickness of sheet is used, the strength and rigidity of the prod. are increased.