Tapered cup and method of forming the same

A method of forming a thin-walled tapered metallic cup, the method comprising:

• providing a stock material;
• forming the cup from a blank of the stock material using a blank and draw operation;
• performing an ironing step on the cup;
• performing a redrawing operation on the cup to provide the cup with a predetermined height and a wall thickness;
• subsequent to the redrawing operation, trimming the cup;
• curling the top edge of the cup to form a lip;
• performing a plurality of further drawing steps to form a plurality of straight walled sections and wherein each of the straight walled sections comprise successively smaller diameters and are separated by at least one of a step and a rib provided as a transition point between adjacent straight walled sections and to add strength to the cup;
• subsequent to the plurality of drawing steps, expanding each of the straight walled sections to a larger diameter with a die comprising a tapered profile and wherein at least one straight walled section comprises a wall thickness of between approximately 0.0040 inches and 0.0090 inches;
• wherein an uppermost straight walled section comprises a vertical straight walled section having a first diameter;
• forming at least one outwardly oriented annular or semi-annular projection proximal to a bottom of the uppermost straight walled section to provide a contact point for adjacent cups, and wherein the at least one projection is formed by an operation wherein at least the top edge of the cup is held in place and the projection is forced outwardly into a die;
• wherein the projection comprises a second diameter that is between 1.001 and 1.2 times larger than the first diameter and creates a limit to the extent to which the first cup can extend into an adjacent second cup of the same construction and such that a contact point is provided between the projection of a first cup and a curled top edge of the adjacent second cup, and an offset between bottom portions of the first cup and the adjacent second cup is provided by the contact of the projection of the first cup and the curled top edge of the second cup;
• wherein a variable distance is provided between adjacent cups along a height of the cup below the contact point;
• and
• wherein a gap is provided between a lowermost portion of the first cup and an upper portion of a first panel of the second cup, said gap comprising a gap of between approximately 0.001 inches and 0.006 inches.