A sheet pressing device includes a carry-in port that receives a Z-folded sheet having two folds; an additional folding roller disposed downstream of the carry-in port to press the fold; a lower folding guide having a pedestal disposed opposite to the additional folding roller; a first moving mechanism that moves the additional folding roller between a pressing position at which the additional folding roller is made to approach the pedestal and a retreat position at which the additional folding roller is moved relative to the pedestal from the pressing position; a second moving mechanism that moves the additional folding roller along the fold; and a control part. The control part controls the second moving mechanism so as to increase the number of times the additional folding roller is moved along the fold when a sheet section is positioned between the additional folding roller and the fold.

Disclosed herein is a sheet-folding apparatus which includes transporting rollers, folding rollers, a pushing member provided between the transporting rollers and the folding-rollers, and a guide unit for guiding the sheet to the folding-roller pair by using the pushing member.

Provided is a sheet folding apparatus for folding sheets, including: a feeding-roller pair; a loop-forming space provided downstream from the feeding-roller pair, for forming a sheet loop; a pushing member for pushing the looped sheet; a folding-roller pair for nipping a prescribed part of the sheet pushed by the pushing member, thereby to fold the sheet; and a path provided between the feeding-roller pair and the folding-roller pair, for guiding the sheet fed from the feeding-roller pair toward the loop-forming space.

A sheet pressing apparatus includes an inlet port for receiving a sheet having a folding line; additional folding rollers supported by a supporting member arranged downstream from the inlet port; a lower folding guide opposing the additional folding rollers; a first drive mechanism configured to move the additional folding rollers between a pressing position, at which the additional folding rollers approach the lower folding guide to press the sheet at the folding line, and a retreat position to which the additional folding rollers are moved from the pressing position, separating from the sheet; and a second drive mechanism configured to move the additional folding rollers along the folding line. The additional folding rollers are arranged such that one end of the folding line exists between the two additional folding rollers provided at one position and the additional folding roller at the other end position is arranged on the folding line.

A sheet folding processing device includes a folding processing mechanism that includes a folding roller pair for forming a plurality of folds on the sheet conveyed in a predetermined sheet conveying direction to produce Z-fold, additional folding rollers and a lower folding guide. The additional folding rollers and the lower folding guide are arranged on the downstream side of the folding roller pair in the sheet conveying direction to face each other and cooperate with each other to press the folds. The interval between the folding roller pair and the additional folding rollers is determined such that when the leading fold as viewed in the sheet conveying direction is pressed between the additional folding rollers and the lower folding guide, the sheet part having a plurality of layers of sheet where the sheet is folded between the additional folding rollers can also be held between the folding roller pair.

The sheet pressing apparatus includes an inlet port configured to receive a sheet having a folding line; additional-folding rollers arranged downstream of the inlet port and configured to press the sheet at the folding line; a lower folding guide opposing the additional-folding rollers; a first drive mechanism configured to move the additional-folding rollers between a pressing position, at which the additional-folding rollers approach the lower folding guide to press the sheet at the folding line, and a retreat position to which the additional-folding rollers are moved with respect to the lower folding guide from the pressing position; a second drive mechanism configured to move the additional-folding rollers along the folding line; and a restriction member configured to restrict, at a preset restriction position, the sheet thickness at the folding line to a value equal to or less than a prescribe value, while the additional-folding rollers are moving.

A post-processing apparatus (1) includes a first conveyance path (41), a first processing part (55), a second conveyance path (95) and a merging conveyance path (97), and the first processing part (55) includes a conveying rollers pair (80) including a first roller (81) and a second roller (83) conveying the sheet along a first direction; a first folding rollers pair (84) including the first roller (81) and a third roller (85) forming a first nip, conveying the sheet along a second direction and performing a folding processing along a first fold line; a second folding rollers pair (86) including the third roller (85) and a fourth roller (87) forming a second nip, conveying the sheet along a third direction and performing a folding processing along a second fold line; a first folding guide (89) movable to the first nip; and a second folding guide (91) movable to the second nip.

An image forming system is configured to execute a printing process to a sheet based on a job for generating output products, and to print index information required for sorting the output products for the respective jobs on a partition sheet. A folding process unit is allowed to designate a folding position of the partition sheet so that at least a part of the index information printed on the respective partition sheets is visible from a predetermined direction.

A sheet processing device for pressing a fold line formed in a sheet, the sheet processing device comprises a pressing portion configured to press a sheet while rotating about a rotation axis. The pressing portion includes a pressing unit having a projecting shape, disposed over a predetermined range in a direction of the rotation axis to have a position in a rotation direction about the rotation axis changed according to the direction of the rotation axis, and an impact absorbing member provided at a part of the pressing unit of the pressing portion, abutting on the sheet at first in the rotation direction of the pressing portion, the impact absorbing member configured to reduce impact upon abutting on the sheet.

A sheet folding apparatus includes a conveyor, a first folding roller, a second folding roller, a third folding roller, a guide, a motor, and a driving force transmission mechanism. The motor causes the second folding roller to perform either forward rotation in which the second folding roller rotates to convey a sheet on a main conveying path in a conveying direction and to convey the sheet on a reflux conveying path from a joining position toward a branching position or backward rotation in a direction opposite to the forward rotation. The driving force transmission mechanism rotates the guide toward a first posture from a second posture in conjunction with the forward rotation of the second folding roller and rotates the guide from the first posture toward the second posture in conjunction with the backward rotation of the second folding roller.