Sheet processing apparatus having binding unit and image forming system thereof

A sheet processing apparatus comprising:

• a conveying unit configured to convey sheets;
• a stacking unit configured to stack the conveyed sheets to form a sheet stack;
• and
• a binding unit configured to include a pair of toothed jaw of an upper tooth jaw and a lower tooth jaw arranged to face each other, and bind the sheet stack by pressing the sheet stack between the pair of toothed jaw,
• wherein at least one of the upper tooth jaw and the lower tooth jaw includes a base, a top-land portion, and side edges between the base and the top-land portion,
• wherein ridgelines between four sides of the top-land portion and the side edges are chamfered, and
• a rounding radius of the top-land portion is larger than a rounding radius of the side edges.

A sheet processing apparatus comprising

• a binding unit configured to include a pair of toothed jaw of an upper tooth jaw and a lower tooth jaw arranged to face each other, and bind a sheet stack by pressing the sheet stack between the pair of toothed jaw, wherein
• wherein at least one of the upper tooth jaw and the lower tooth jaw includes a base, a top-land portion, and side edges between the base and the top-land portion,
• wherein ridgelines between four sides of the top-land portion and the side edges are rounded, and
• a rounding radius of the top-land portion is larger than a rounding radius of the side edges.