METHOD AND MEANS FOR FITTING A CELL IN A WATCH CASE IN A FLUID TIGHT MANNER

摘要

A cover 20 for a cell cavity 7 in a plastic watch case 2 is provided on its periphery with three lugs 28. The back surface 4 of the case is provided with three recesses 12 into which the lugs can enter freely. With the aid of a tool 38, the cover is rotated while ultrasonic or thermal energy is applied to the lugs. Thanks to this energy, the lugs themselves deform and move into the thermoplastic material in order thereby to form three undercuts. A bayonet joint closure assembly is thus formed. See FIG. 5.