Method and an apparatus for folding a medium

A folding apparatus, which comprises a rotatable folding cylinder,

• a first and second rotatable press member, each adapted to engage with said folding cylinder to form, respectively,
• a first and second folding pinch, and
• a medium feed means for feeding the medium towards the folding cylinder in between said first and second folding pinches,
• wherein the folding apparatus further comprises control means for controllably driving the drive means and alternating the rotational direction of the rotatable folding cylinder during a folding program and controllably driving the medium feed means to feed the medium during a folding program towards the folding cylinder and further includes skew detecting means, wherein the medium feed means, in an operative state are adapted to correct for the medium skew.

A method of folding a medium in a folding apparatus containing a rotatable folding cylinder, a first rotatable press member capable of engaging said folding cylinder to form a first folding pinch, a second rotatable press member, capable of engaging with said folding cylinder to form a second folding pinch, a blouse curvature, and a medium feed means, said method comprising the steps of:

• a) feeding the medium with the medium feed means towards the folding cylinder and between the first and second pinch;
• b) directing the medium into the first folding pinch formed by engaging said first rotatable press member with said folding cylinder, by rotating the folding cylinder in a first direction;
• c) forming a blouse in the medium in between said feed means and the folding cylinder;
• d) moving said blouse into said second pinch by rotating the folding cylinder in a second direction, opposite to the first direction, and correcting for medium skew prior to executing step a) by driving the feed means in a reverse direction with respect to the feeding direction until the leading edge of the medium is aligned, and
• e) using the blouse curvature to introduce a buffer space to affect medium speed.