3 Fundamentals of press design

Shearing lines
Blanking presses for contoured blanks
Contoured blankshave a complex closed contour (cf. Fig. 2.1.29)and can
contain holes. These blanks are manufactured on blanking presses,
also known as contour blanking lines (Fig. 4.6.5). Blanking presses are
high-speed eccentric or link drive presses similar to single-action car
body presses with a maximum of 80 strokes per minute (cf. Fig. 4.1.19
right and Fig. 4.6.8). They feature a high degree of rigidity as well as
small bearing and gib clearances. The slide – generally with a maximum
stroke of 300 to 450 mm – is mounted using eight guide gibs (cf.
Fig. 3.1.5).
Blanking presses require particular attention to noise reduction.Blanking
noise depends on a number of factors, including the impact speed
of the punch on the sheet metal, and accordingly also the slide velocity
in the work area. Investigations have proven that noise emissions
can be reduced by around 6 dB(A) by halving the slide velocity. In the
case of link drive systems, the impact speed reached is only 30% that of
Fig. 4.6.5 Contour blanking line with nominal press force of 8,000kN
(six-link drive)
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