3 Fundamentals of press design

4 Sheet metal forming and blanking
4.6 Shearing lines
4.6.1 Slitting lines
The parting of coiled sheet metal stock to produce several narrow strip
coils is performed using waste-free cutting with rotating circular shearing
blades in so-called slitting lines. Materials processed in this way include
hot and cold-rolled and stainless steels, NF metals, in particular aluminium,
and coated sheet metals.
Alongside the decoiler and recoiler, the major components of a slitting
line include the circular shear and the brake frame. The starting
coil is pulled tightly off the decoiler, cut to narrow strips with the circular
roller shears and coiled again to form firm rings by the brake
frame and the recoiler (Fig. 4.6.1). The material processed in this way has
generally a thickness of 0.2 and 10 mm. The starting coils can weigh
anywhere between 5 and 30 t. The minimum width of the individual
coil depends on the width of the blade and the thickness of the sheet
metal being processed. Circular shear blades are generally between 10
and 20 mm wide and have a diameter of 250 to 500 mm. The maximum
number of cuts depends on the diameter of the shear shaft and the
shaft length. Shaft deflection must not exceed a certain value.
Circular shears with a continuous shaft are equipped with circular
blades, rolling rings and distance sleeves (Fig. 4.6.2). Alternatively,
hydraulically fastened flanged blades can be used for greater slit coil
widths. To reduce standstill periods, the shears are configured as
exchangeable units that can be pre-assembled outside the running slitting
line prior to production. Where electrically adjustable disk shears
are used, the blade holders are positioned by a control system to the
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998