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 processing apparatus is configured to press a fold line that is formed on a sheet. The sheet processing apparatus includes: a sheet supporting unit configured to support the sheet in a pressing direction for pressing the fold line; a pressing unit configured to press the fold line that is formed on the sheet that is supported by the sheet supporting unit; and a pressing-force generating unit configured to generate a pressing force for pressing the sheet supporting unit against the pressing unit at a central part in a direction along which the fold line is formed.

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 bundle discharging apparatus K, including: a conveyance unit 66 configured to convey a sheet bundle; a guide unit 72 configured to guide the sheet bundle conveyed by the conveyance unit; a discharging unit 90 configured to discharge the sheet bundle to an outside of the sheet bundle discharging apparatus; and a receiving unit 81 configured to receive the sheet bundle guided by the guide unit, wherein the receiving unit includes: a contact portion 81c with which a leading end portion of the sheet bundle, which is guided by the guide unit, in a moving direction of the sheet bundle is to be brought into contact; and a pushing portion 81b, which is formed integrally with the contact portion, and is configured to push a first surface of the sheet bundle, and wherein the receiving unit is rotatable between a first position and a second position, and is configured to receive the sheet bundle in the first position and rotate from the first position to the second position, thereby allowing the pushing portion to push the first surface of the sheet bundle to place a second surface of the sheet bundle, which is on a side opposite to the first surface, on the discharging unit.

A sheet bundle discharging apparatus, including: a guide unit configured to guide a sheet bundle with a spine as a leading end; a receiving unit configured to receive the spine of the sheet bundle guided by the guide unit; and a discharging unit configured to discharge the sheet bundle, wherein the receiving unit includes: a first surface configured to receive the spine at a first position; a second surface configured to push the sheet bundle in a rotation direction of the receiving unit; and a third surface configured to regulate a movement of the sheet bundle in the rotation direction while the receiving unit rotates from the first position to a second position, and wherein a friction coefficient between the sheet bundle and the third surface in a direction away from the first surface is larger than a friction coefficient between the first surface and the sheet bundle.

A sheet processing apparatus is configured to press a fold line that is formed on a sheet. The sheet processing apparatus includes: a sheet supporting unit configured to support the sheet in a pressing direction for pressing the fold line; a pressing unit configured to press the fold line that is formed on the sheet that is supported by the sheet supporting unit; and a pressing-force generating unit configured to generate a pressing force for pressing the sheet supporting unit against the pressing unit at a central part in a direction along which the fold line is formed.

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.