To provide a new necking forming method with a die for forming a reduced smooth necked part in the open end part of a can by a method by which wrinkles or folds are dissolved and the available height for notice in the finished can is maximized.
In the die necking forming method with the die of the open end part of the main body of can so as to enable forming the reduced necked part having smooth external shape, including forming the open end part of the cylindrical side wall 21 of the main body 20 of can by making the open end part of the side wall engage with the die 32 having the external shape of many radii, each of the radii which are continued from the inlet of the die to the outlet is smaller than a preceding radius, angle formed with each of the continuous radii is equal to or smaller than the angle formed with the preceding radius. Next, at the succeeding station of die forming, the necked part whose diameter is gradually reduced is formed with a series of dies, the formation of the undesirable folds in the last shape of the necked part is substantially dissolved with all of the dies and it is preferable to be the external shape of the formed surface composed of many same radii.
DONARUDO AARU HOORUSHII
ROJIYAA EICHI DONARUDOSON
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