(57) A method of and apparatus for bending a corrugated sheet transversely of the direction
of corrugation, the corrugated sheet being of the type having a plurality of parallel
ridges and troughs formed by ridge tops (17) connected to ridge bottoms (18) by intermediate
side walls (19 and 20). The apparatus comprises a first tool (11) in the form of a
pressure bar formed along the length thereof with alternating projections (16A) and
notches (16B) and a second tool (10) in the form of an elongate member (12) carrying
a plurality of projections (13), a channel (14) being provided in each projection
(13) to receive the first tool (11) in use of the apparatus. In use of the apparatus,
a corrugated sheet is pressed between the first and second tools so that each projection
(13) of the second tool (10) enters a respective valley between two ridge tops (17)
of the corrugated sheet and the first tool (11) enters the channels (14) of the projections
(13) to form a fold (22) extending transversely of the corrugations and into the valleys
of the corrugated sheet. The trough bottom (18) of each corrugation is brought into
contact with the base of the respective notch (16B) during the pressing operation
and at the same time the side walls (19 and 20) of the respective valley contact the
edges of the notch (1 6B) whereby the portions (19A and 20A) of the side walls between
the point of contact with the notch edge and the trough bottom (18) are moved away
from the valley (21) and the portions (19B and 20B) of the side walls between the
point of contact and the ridge top are moved into the valley.
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