| 摘要 |
A method of forming a liquid-tight up comprising a cup-like body and a sheet member disposed around the peripheral surface of the cup-like body, with the sheet member being corrugated to provide a plurality of concavo-convex flutes, whereby air compartments are provided between the peripheral surface of the cup-like member and the inner surface of the sheet member, comprises forming the sheet member by cutting, from a planar sheet, a planar blank having a width in excess of the peripheral length of the circular bottom of an inner cup member and a length substantially equal to the height of the side wall of the inner cup member. The opposite ends of the planar blank are then united in overlapped relation to form a circular cross-section sleeve constituting an outer member and, after such uniting, the blank is formed with concavo-convex flutes to form a structure whose peripheral surface is corrugated. The inner and outer members are then telescoped to form a composite liquid-tight cup with heat insulating air passages extending upwardly along the outer surface of the side wall of the inner cup member. |
