(57) Machine for high speed folding in accordion-like manner bands (102) of elastic materials
such as paper, thin plastic laminates or metal sheets coming from coils on which they
are stored in a rolled up form, coprising an orientable guide (104) launching said
band (102) against an obstacle (24, 26) so as to cause a length of said band (102)
to be bent in arc-shaped manner, thus forming a loop (150), towards a first roller
(20) having circumferential grooves (40) and areas (136, 138, 140) having high friction
coefficient with respect to the material of the band (102) to be folded, said roller
(20) being rotated at a speed such that its peripheral speed is greater than the advancing
rate of said band (102), whereby the loop (150) formed by said band (102) is drawn
by said roller (20) up to impinge against relieves (32) engaged within said circumferential
grooves (40), causing said band (102) to be pinched, thus forming a sharp fold and
then to start again the arc shaped folding in the opposite direction until it comes
into contact with said loop (150) a second roller (22), fully identical to the first
one (20), whereby the band (102) is pinched between said roller (22) and corresponding
relieves (36) engaged in circumferential grooves thereof (44), the band (102) being
thus sharply folded again and returned towards said first roller (20), and so on,
whereby an accordion folded package of band (166) is formed up to the desired size.
The presence of possible crossing weakening areas in said band (102) at regular spacings
makes the size of the accordion folded zones essentially independent from the distance
between said first and second rollers (20, 22).
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