Curling and Wiring Dies
These dies are used for curling over the tops of the cans, basins, milk pans,
or other sheet metal articles. The wire is added to give greater strength and
Figure 3. Steps in Curling the Edge of a Utensil.
If the vessel has straight sides the curling may be done with one stroke of
the press, but if the sides slant the top must first be bent over and then caught
in the curling groove and curled.
Seaming is the permanent joining of two metal
edges. It may be done by simply hooking the bent edges over each other, or,
for a locked seam, a double fold is made. For the double seaming of such pieces
as the bottoms of teapots, pails, and similar articles, special machinery is
Figure 3 shows how the curled edge of a half-round dish is formed by the pressure
of a die. In the first stage the metal has commenced to curl, in the next it
has curled to a half-circle, in the third it has begun to turn back on itself,
and in the last it curls to a full circle.