Sheet processing apparatus and image forming system

An image forming system comprising:

• an image forming apparatus that forms an image on a sheet;
• and
• a sheet processing apparatus capable of folding the sheet along a folding line, wherein
• the sheet processing apparatus includes:
• a conveying path forming member that forms a sheet conveying path having a curved portion through which a front edge of the sheet passes at a downstream side at least in a sheet conveying direction;
• a sheet conveying unit that conveys the sheet along the sheet conveying path;
• a sheet folding unit that folds the sheet along the folding line in the sheet conveying path, and then conveys the sheet toward a discharge direction with the folding line discharged first as a front edge;
• and
• a sheet position defining unit that defines a position of the front edge of the sheet at the downstream side of the sheet conveying direction in the curved portion of the sheet conveying path so that a target position of the folding line on the sheet coincides with a folding position of the sheet folding unit, wherein
• the sheet position defining unit is configured to be capable of adjusting an inclination of the front edge of the sheet in the curved portion of the sheet conveying path, and wherein the sheet position defining unit includes:
• an abutting member that abuts on the front edge of the sheet;
• an abutting position defining shaft that makes the abutting member rotatable so as to change the abutting position with the front edge of the sheet in the curved portion of the sheet conveying path;
• and
• a sheet inclination correcting shaft that is disposed so as to intersect with the abutting position defining shaft, and makes the abutting member rotatable so as to change an inclination of the front edge of the sheet in a width direction which intersects with the sheet conveying direction in the sheet conveying path.