Figure 2-38. - Slip roll forming machine.

Figure 2-39. - Forming cylinders on rolling forms.

rolls for the purpose of accommodating a wired edge when forming a section with this type edge or for rolling wire into a ring.

COMBINATION ROTARY MACHINE. - Preparing sheet metal for a wired edge, turning a burr, beading, and crimping are probably the most difficult of sheet-metal forming operations to perform. When production dictates, large shops will have a machine for each operation. However, a COMBINATION ROTARY MACHINE (fig. 2-40) with a selection of rolls will prove acceptable for most shop uses.

Wiring an Edge. - The wire edge must be applied to tapered shapes after they are formed. This is accomplished by turning the edge on the rotary machine. Gradually, lower the upper roll until the groove is large enough for the wire. The edge is pressed around the wire with the rotary machine (fig. 241).

The wire edge can be finished by hand if a rotary machine is not available. The edge is formed on the

Figure 2-40. - Combination rotary machine with extra forming rolls.

Figure 2-41. - Turning a wire edge with a rotary machine.