3 Fundamentals of press design

Shearing lines
Fig. 4.6.1 Slitting line
programmed width. Width-adjustable shears permit easy trimming of
sheet metal coils of different widths.
The brake frame applies the necessary restraining force to the slit
sheet metal, thus allowing it to be recoiled under sufficient tension.
The specific tensile stress levels in the coiling lines lie between 10 and
20 N/mm 2 . The brake frame used depends on the type of coil stock
processed, the treatment or coating of the metal surface, the necessary
coiling quality and the thickness and strength of the sheet metal. An
underlying difference is drawn between plate-type brakes and rotating
brake systems. The plate-type brake applies pressure through braking
felt-carrying plates positioned above and below onto the surface of the
sheet metal. Because of the 100 % slip between the braking felt and the
surface of the coil material, this braking method can only be used on
sufficiently insensitive surfaces. The braking energy generates heat in
the slit coil. Where rotating brake systems are used, slip can be reduced to
5 %, avoiding damage of the material surface.
A coil loop must be provided between the circular shear and the brake
frame. This is used to accommodate the length differences in coiling
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