Crown closure

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Considering first the prior art and looking at FIGS.
1, 2 an 3 in particular, one can see that a cap blank comprises a slightly domed roof 12 with a downwardly extending skirt 13, of which the peripheral margin is outwardly flared and comprises a plurality of equally spaced apart ribs 14 and intermediate non-ribbed portions 15.
A conventional gasket 16 may be applied to the under-side of the roof 12.
When the blank of FIG.
2 is applied to the top of a bottle and a cylindrical closure forming tool brought down upon it, it is changed into the cap of FIG.
3 wherein the corresponding skirt portions bear the same reference numerals as in FIG.
2.
It will be seen that the ribs 14 are straightened so as to extend vertically downwardly whereas the portions 15 are forced underneath the bead rimming the bottle pouring opening (not shown).
FIG.
3 shows the grooves 17 formed in the intermediate portions 15 by the thread formation normally provided on the bottle finish when a screw-off type seal is required.
The shaping and nature of the ribs 14 may perhaps be better appreciated by reference to FIGS.
7 and 8 which shows the female die in which the blank was originally shaped and with which it conforms.
It will be seen that the ribs 14 would conform to the shape of the die recesses 18 so that each rib is relatively narrow at its free end whereas the portions 15 in the blank are broad conforming with the spaces 19 in the die intermediate the recesses 18.
The blank of FIGS.
4 and 5, the formed cap of FIG.
6 and the die of FIGS.
9 and 10 conform to crown seal blanks of the present invention and it will be seen that ribs 24 corresponding to ribs 14 of the prior art are relatively shallow throughout and appreciably broader at their peripheral edge than are ribs 14.
For descriptive convenience the integers appearing in FIGS.
4, 5, 6, 9 and 10 have reference numerals corresponding to those of the corresponding integers of the prior art drawings but with the prefix 2 instead of the prefix 1