Provided is a sheet processing device capable of preventing a folded sheet bundle from being opened after pressing to improve accumulating property and aligning property of the sheet bundle. A sheet processing device includes: a pair of sheet pressing members 70 that press a fold of a folded sheet bundle in a thickness direction of the fold; and a moving member 56 that moves the sheet pressing member pair 70 along the fold of the folded sheet bundle. The moving member 56 supports a plurality of rows of the sheet pressing member pairs 70 arranged in a moving direction of the moving member 56. The sheet pressing member pairs 70 press the folded sheet bundle with the intervals therebetween in the respective rows reduced stepwise in the moving direction of the moving member 56.

A sheet pressing device of the present invention includes: a pair of pressing rollers 70 that press, in a fold thickness direction, a fold of a folded sheet bundle BS conveyed in a folded state; and a pressing roller unit 56 that moves the pressing roller pair in a sheet fold direction while supporting the same. The pressing roller pair 70 presses the fold in one of a first region R1 where rollers of the pressing roller pair 70 are brought into pressure contact with each other and a second region R2 adjacent to the first region R1 on an upstream side thereof where rollers of the pressing roller pair 70 are opposed to each other at an interval. With this configuration, it is possible to minimize damage on a sheet end portion and reduce a moving load of the pressing roller pair 70.

A fold-enhancing device includes a pressing member, at least one retaining member, and a moving mechanism. The pressing member presses against a fold line of a recording-medium bundle folded into a booklet shape. The recording-medium bundle is obtained by stacking multiple sheets of recording media. The retaining member retains the recording-medium bundle and is provided at a position located away from the fold line in a direction intersecting the fold line and not in contact with the pressing member. The moving mechanism moves the pressing member and the retaining member in a direction extending along the fold line.

A sheet processing apparatus includes a pressing unit and a shifting unit. The pressing unit has a protrusion and presses the protrusion against a fold section of a sheet. The fold section extends in one direction. The shifting unit moves at least one of the protrusion of the pressing unit and the sheet so as to shift a pressing position, at which the fold section is pressed by the protrusion, in the one direction or in a direction opposite to the one direction.

A sheet processing apparatus includes a center folder, a back-crimp binder, and circuitry. The center folder performs a center-folding process to form a fold portion on a sheet bundle including multiple sheets. The back-crimp binder includes a back-portion former and a crimp binder. The back-portion former forms a back portion of the fold portion on the sheet bundle subjected to the center-folding process. The crimp binder performs a crimp-binding process on the back portion of the sheet bundle subjected to the center-folding process. The circuitry is to cause the back-crimp binder to form a crimp mark parallel to the fold portion on the back portion of the sheet bundle.

A sheet processing apparatus includes: a center-folder to perform a center-folding process on a sheet bundle including multiple sheet materials; a back-crimp binder to: form a back portion on the sheet bundle subjected to the center-folding process; and perform a crimp-binding process on the back portion; and a controller configured to: cause the center-folder to perform the center-folding process; and cause the back-crimp binder to perform the crimp-binding process on the back portion while forming the back portion on the sheet bundle in the crimp-binding process.

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.

Provided is a sheet processing device capable of preventing a folded sheet bundle from being opened after pressing to improve accumulating property and aligning property of the sheet bundle. A sheet processing device B that presses a folded sheet bundle includes a pair of pressing rollers 70 that press a fold of the folded sheet bundle in a thickness direction of the fold, a pressing roller unit 56 that moves the pressing roller pair 70 along the fold of the folded sheet bundle, and a cam member 80 that regulates an interval between the pressing roller pair 70. When the pressing roller unit 56 is moved along the fold of the folded sheet bundle to press the fold in the fold thickness direction, the cam member 80 reduces stepwise the interval between the pressing roller pair 70 in accordance with a moving direction of the pressing roller unit 56.

Provided herein is a device for folding a stack of sheets. The device includes a frame, means for pre-folding a stack of sheets along a crease line into a main plane such that a booklet with a straight back is obtained, means for keeping the pre-folded booklet relative to the frame, a carriage movably arranged to the frame and moveable parallel to the back of the booklet, and a nip arranged to the carriage for receiving the back of the pre-folded booklet. The nip direction forms an angle greater than zero with respect to a direction of movement of the carriage.

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.