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.

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 sheet processing apparatus includes a folding device to fold a sheet and a fold-enhancing device to press a folded portion of the sheet folded by the folding device to perform enhanced folding processing on the sheet whose trailing edge has exited the folding device.

A sheet folding apparatus folds two portions of a first folding position of a sheet and a second folding position existing between one end of the sheet and the first folding position to perform Z-fold on the sheet. Then, in a state in which a one-end side portion of the sheet and a folded portion folded in the first folding position are overlapped with each other, the apparatus adjusts a distance between one end of the sheet and the first folding position.

A sheet folding apparatus includes a conveyance member to convey a sheet from an ejection member at a first speed lower than a conveyance speed by the ejection member or a second speed substantially same as or higher than the conveyance speed; a registration member; a pair of first and second rollers to rotate in forward and reverse directions; a plurality of folding rollers downstream from the second roller, to rotate in forward and reverse directions to fold the sheet; and circuitry to determine whether the sheet is equal to or smaller than a reference length from an exit position from the ejection member to a folding start position downstream from the pair of the first and second rollers. The circuitry performs first-speed folding when the sheet is equal to or smaller than the reference length and performs second-speed folding when the sheet is longer than the reference length.

A sheet folding processing apparatus suppresses an increase in size and cost of the apparatus and performs folding processing on continuously conveyed sheets. In the sheet folding processing apparatus, a sheet conveyed by a feeding roller pair and hang in a loop shape in a loop forming space is pushed into a nipping portion of a folding roller pair by a pushing plate, so that the sheet is folded in a Z-shape to form a plurality of fold lines. The sheet is conveyed in the conveyance direction until the sheet rear end passes through the feeding roller pair, and after the sheet rear end is stored in a loop forming space by moving the pushing plate from a position for pushing the sheet into a nipping portion to a retracting position, the reinforcing processing of the fold line of the sheet is performed by an additional folding unit.

A sheet folding processing apparatus performs folding processing on continuously conveyed sheets without lowering productivity. A sheet folding processing apparatus includes a conveyance roller pair, a folding roller pair forming a plurality of fold lines by bending a sheet conveyed from the conveyance roller pair in Z-shape, an additional folding roller and a lower folding guide arranged downstream of the folding roller pair to face each other and pressing the fold line of the sheet in corporation with each other, and a controller controlling operation of the above. The controller controls the folding roller pair to convey the sheet with the fold line downstream in a conveyance direction until the fold line passes through the additional folding position by a predetermined conveyance amount, to return the sheet upstream by reversely rotating the folding roller pair, and to position the fold line to the additional folding position for additional folding processing.

A fold-enforcing assembly includes a fold-enforcing device, a moving device to move the fold-enforcing device in a direction of a fold of a sheet bundle, and control circuitry. The fold-enforcing device includes a pressing member pair to nip and press the fold of the sheet bundle in a direction of thickness, a pressing mechanism to pressurize and depressurize the pressing member pair, and a driver to drive the pressing mechanism. Controlled by the control circuitry, the moving device moves the fold-enforcing device in accordance with a size of the sheet bundle in the direction of the fold; pressing mechanism pressurizes the pressing member pair to press a first end portion of the sheet bundle in the direction of the fold; the moving device moves the fold-enforcing device to a second end portion of the sheet bundle; and pressing mechanism depressurizes the pressing member pair in the second end portion.

A sheet folding system includes a plurality of sheet folding apparatuses configured to receive and perform a folding process on a sheet and circuitry configured to distribute sheets to the plurality of sheet folding apparatuses. Each of the plurality of sheet folding apparatuses includes a folding device configured to fold the sheet, a first conveyance passage configured to convey the sheet downstream in a sheet conveyance direction without passing through the folding device, a second conveyance passage configured to convey the sheet to the folding device, a third conveyance passage configured to convey the sheet from the folding device downstream in the sheet conveyance direction, and a junction between the first conveyance passage and the third conveyance passage. The circuitry controls sheet conveyance to prevent an interference, at the junction, between the sheet conveyed from the first conveyance passage and the sheet conveyed from the third conveyance passage.

In a sheet folding apparatus for folding a sheet, a sheet is pushed at a predetermined position thereof by a push member while the sheet is being conveyed by a conveyance roller. The predetermined position of the sheet is guided to the nip section of a folding roller pair. Then, the sheet is nipped at the predetermined position thereof and folded by the folding roller pair.