by the same die, according to the length of stroke to which the die is set.

When the edge of a shell of the shape shown at Fig. 524 is desired to be curled as shown at 526 the work will require two

Carling Punch

The Work

Bolater

FIG. 523.

dies. The first die is to bend or form the edges to the upright position and the second die to curl the edge. This second die is

A

shown in Fig. 527.

FIG. 524.

The upper die is made so as to make the

entering of the edge of the shell positive within the curling

groove, and also so that the straight inner wall will hold the wall of the shell while the edge is curling, thus preventing any bulg

ing during the process, which would occur if the inside of the tool was finished like the outside. In this manner the metal is held tightly, and as the ram descends it must follow the shape of the curling groove.

The curling of the edges of drawn shells by means of dies of the above type is done in endless variety; the articles worked

upon ranging from shoe eyelets to bath-tubs, of both round and irregular shapes. The design and construction of the tools depends on the shape, the thickness of metal, and the diameter of

curl required; however, the principles of construction involved are the same in all of them.

The tools in Fig. 530 show how shells of different shape may be curled. For the operation shown at A and B a combination die and a bending die, respectively, are used. The curling as shown at C is done in the die shown.

The manner in which curling dies are used for "wiring" on both large and small work will be understood from Figs. 531 and 532.

Dies of this type may be used for "wiring" or simple "curling" on round or oval shells, as long as they are straight or

nearly straight walled, and are properly supported during the process. A tool-steel ring A is attached to the punch-holder. The inner diameter of this ring must fit accurately the inside of

the shell to be wired, so as to prevent bulging or crimping of the walls. When "wiring," the ring B is used in the lower die.

When the dies are in use a wire hoop, which fits the outer diameter of the shell, is placed in position on the ring B and around the shell which is located within the dies as shown. The

ram then descends and the edge of the shell is curled around the hoop, enclosing it within it, as shown at the bottom of the cut.

A curling punch and die for curling deep shells or articles of thin sheet metal, and a section of the press in which it was

FIG. 531.

The punch is located and fastened within the ram, while the die is on a sliding table which may be pulled back and forth by the operator. The horn or die for

locating the work is of slight taper, and consequently a solid onepiece curling punch can be used, as the decrease in diameter when curling is so slight that contraction of the curling ring is unnecessary. When in use, the table on which the horn or die

is located is pulled out to allow the article to be slipped over it. This is done, and the table is moved back to place against the stop shown. The punch then descends and the edge of the article is curled.

The punch ascends, the table is pulled out, the

FIG. 5.

work is removed, another piece is located, and the operation is repeated. When a press with an automatic die slide is used the curling or wiring is done more rapidly.

MANUFACTURING ARMATURE DISKS AND

SEGMENTS.

The adoption and use of dies, power-presses, and special sheetmetal working machinery for the economic production of parts of electrical apparatus has had great development during the past few years; so that to-day establishments that manufacture sheet-metal working machinery dispose of a great portion of their product to electrical machinery manufacturing concerns. One has only to examine an electrical device or a machine to realize what a factor the power-press has become in their production. The parts of electrical apparatus for the production of which such machinery is used most extensively, are armature disks and segments for motors. It is at once obvious that the requirements for such work have led to the designing of dies, presses, and special machinery which differ in essential details from those used in the general and more familiar classes of sheetmetal working.