| 摘要 |
<p>A metal cap for closing a container, e.g. a glass container for foodstuffs, of the kind comprising a cap base extending over the container mouth and beyond its outer edge and a separate encircling cap skirt secured to the container by a screw or bayonet connection and engaging over the edge of the cap base; the cap base being originally curved inwards, but being forced into an outward curve by the anchoring forces acting on its edge when the skirt is secured over it and subsequently being curved inwards again by reduced pressure formed in the container. Loss of pressure is thus indicated by a return to the outwardly curved condition. The region of the cap base projecting beyond the outer edge of the container mouth has a downwardly widening conical edge portion engaged by a rolled-in bead on the upper end of the cap skirt. The adjacent portion of the cap skirt may be conically tapered, and the conical edge portion of the cap base may terminate in an out-turned stiffening flange. The circle of contact preferably lies slightly below the plane of the container mouth. Good engagement and sealing are thereby obtained as well as reliable inward and outward curving of the cap base.</p> |
