A pair of tooth portions has a plurality of convex portions and is arranged to engage with each other when approaching each other. The convex portion of at least one tooth portion of the pair of tooth portions has, on an opposing surface thereof opposing the convex portion of the other tooth portion, an abutting surface abutting against the convex portion of the other tooth portion when the pair of tooth portions is engaged with each other and a non-abutting surface not abutting against the convex portion of the other tooth portion when the pair of tooth portions is engaged with each other.

The present apparatus includes a placement tray to place sheets to undergo binding processing, and a press bind unit shifting along an end edge of sheets on the placement tray. The press bind unit includes a receiving tooth, and pressing teeth meshing with the receiving tooth to perform press binding on sheets nipped therebetween, and the pressing teeth are provided to shift between a press position for meshing with the receiving tooth, and a retract position spaced apart from the receiving tooth so as to shift the press bind unit along the end edge of sheets with the sheets disposed between the receiving tooth and the pressing teeth. By shifting the pressing teeth to the retract position, it is possible to shift the sheet bind apparatus smoothly along the end edge of a bunch of sheets with the sheets disposed between the receiving tooth and the pressing teeth.

The present apparatus includes a placement tray to place sheets to undergo binding processing, and a press bind unit shifting along an end edge of sheets on the placement tray. The press bind unit includes a receiving tooth, and pressing teeth meshing with the receiving tooth to perform press binding on sheets nipped therebetween, and the pressing teeth are provided to shift between a press position for meshing with the receiving tooth, and a retract position spaced apart from the receiving tooth so as to shift the press bind unit along the end edge of sheets with the sheets disposed between the receiving tooth and the pressing teeth. By shifting the pressing teeth to the retract position, it is possible to shift the sheet bind apparatus smoothly along the end edge of a bunch of sheets with the sheets disposed between the receiving tooth and the pressing teeth.

A binding apparatus includes: a first toothed part including teeth arranged in one direction; and a second toothed part that includes teeth arranged in the one direction and is configured to mesh with the first toothed part and to press a bundle of sheets, wherein at least one first groove is formed between adjacent teeth of the first toothed part, the first groove has cross-sectional areas at central and end portions in a direction orthogonal to the one direction and a direction in which the first and second toothed parts mesh with each other, the one direction and the orthogonal direction are normal to the cross-sectional areas, and the cross-sectional area at the end portion is larger than the cross-sectional area at the central portion.

A binding apparatus includes: a first toothed part including teeth arranged in one direction; and a second toothed part that includes teeth arranged in the one direction and is configured to mesh with the first toothed part and to press a bundle of sheets, wherein at least one first groove is formed between adjacent teeth of the first toothed part, the first groove has cross-sectional areas at central and end portions in a direction orthogonal to the one direction and a direction in which the first and second toothed parts mesh with each other, the one direction and the orthogonal direction are normal to the cross-sectional areas, and the cross-sectional area at the end portion is larger than the cross-sectional area at the central portion.

A sheet post-processing device includes: an alignment member which aligns a sheet bundle on a stacking tray; and a stapler which performs binding processing on a rear end of the sheet bundle. The stapler includes: a first stapler which moves along the rear end of a first sheet bundle and performs the binding processing on a plurality of positions at the rear end of the first sheet bundle; and a second stapler which performs, at one part of an end portion of the rear end on one side, binding processing different from the first stapler. The alignment member includes: a first alignment member and a second alignment member which align the sheet bundle in a first stacking position; and a third alignment member which is fixed to a position corresponding to the second stapler and which aligns the sheet bundle in a second stacking position with the first alignment member.

A sheet post-processing device includes: an alignment member which aligns a sheet bundle on a stacking tray; and a stapler which performs binding processing on a rear end of the sheet bundle. The stapler includes: a first stapler which moves along the rear end of a first sheet bundle and performs the binding processing on a plurality of positions at the rear end of the first sheet bundle; and a second stapler which performs, at one part of an end portion of the rear end on one side, binding processing different from the first stapler. The alignment member includes: a first alignment member and a second alignment member which align the sheet bundle in a first stacking position; and a third alignment member which is fixed to a position corresponding to the second stapler and which aligns the sheet bundle in a second stacking position with the first alignment member.

A recording material processing apparatus includes first teeth that are used for binding processing of a recording material bundle; second teeth that move along a linear route toward the first teeth and presses the recording material bundle located between the first teeth and the second teeth; and a guide portion that is disposed along the linear route and guides the second teeth moving toward the first teeth.

An image forming apparatus includes: a needleless binding device configured to form a recessed or raised impression as a needleless binding part by performing needleless binding on a bundle of sheets; an environment sensor; and a controller configured to perform, based on a value detected by the environment sensor, control to display a confirmation image requesting a user to make confirmation on the needleless binding prior to execution of the needleless binding.

An image forming apparatus includes: a needleless binding device configured to form a recessed or raised impression as a needleless binding part by performing needleless binding on a bundle of sheets; an environment sensor; and a controller configured to perform, based on a value detected by the environment sensor, control to display a confirmation image requesting a user to make confirmation on the needleless binding prior to execution of the needleless binding.