MANUFACTURE OF NECKING-IN CAN

摘要

PURPOSE:To improve the quality of a necking part by limiting the contraction rate and diameter reducing amt. of a necking part within the specified range respectively and setting the difference in the curl opening diameter of a can lid and the can shell flange outer diameter within the specified range. CONSTITUTION:A 1st seaming is effected with the group 9 of a 1st seaming roll 5 and the can sheel head part is pressed by a lower jaw part 10 as well to effect necking. The diameter reducing rate of the necking part is limited within 5% and its amt. within 3.5mm by pressing the necking part with a lower jaw part 11 simultaneously with performing a secondary seaming by a 2nd seaming roll 8. Moreover the difference in the curl opening diameter of the lid and the can shell flange outer diameter is regulated within the range of 0.2mm-1.7mm. Thus, the wrinkle on the neck part is prevented even if the dispersion in the dimension and shape at the flange forming time exists and the breakdown of coating films is eliminated as well. Consequently the quality of the necking part is improved.