A sheet processing apparatus includes a roller pair configured to convey a sheet, a sheet bundle conveyer configured to convey a sheet bundle to the roller pair, and circuitry configured to cause the sheet bundle conveyer to contact leading edges of sheets of the sheet bundle to the roller pair and cause the roller pair to rotate in reverse to align the leading edges of the sheets of the sheet bundle.

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 processing apparatus includes a roller pair configured to convey a sheet, a sheet bundle conveyer configured to convey a sheet bundle to the roller pair, and circuitry configured to cause the sheet bundle conveyer to contact leading edges of sheets of the sheet bundle to the roller pair and cause the roller pair to rotate in reverse to align the leading edges of the sheets of the sheet bundle.

A folding or interfolding unit of a plurality of sheets of paper comprising a first and a second folding or interfolding roll to fold, or interfold, the plurality of sheets of paper according to a predetermined folding or interfolding configuration, at a folding or interfolding zone. Each folding or interfolding roll comprises a tubular body which rotates about a longitudinal rotation axis oriented along a horizontal direction and a plurality of gripping groups integral in rotation with the tubular body. Each gripping group comprises a mechanical gripping member configured to move, at a gripping point, from a releasing configuration to a gripping configuration, where is arranged to mechanically hold the, or each, sheet up to a releasing point having a second angular position.

A folding or interfolding unit of a plurality of sheets of paper comprising a first and a second folding or interfolding roll to fold, or interfold, the plurality of sheets of paper according to a predetermined folding or interfolding configuration, at a folding or interfolding zone. Each folding or interfolding roll comprises a tubular body which rotates about a longitudinal rotation axis oriented along a horizontal direction and a plurality of gripping groups integral in rotation with the tubular body. Each gripping group comprises a mechanical gripping member configured to move, at a gripping point, from a releasing configuration to a gripping configuration, where is arranged to mechanically hold the, or each, sheet up to a releasing point having a second angular position.