Sheet pressing apparatus and image forming system having the same

A sheet pressing apparatus designed to perform an additional folding on a sheet already folded and having a folding line, and comprising:

• an inlet port configured to receive a sheet having a folding line made in a folding process and transported in a prescribed transport direction;
• a first pressing member arranged downstream of the inlet port, as viewed in the transport direction, and configured to press the sheet at the folding line;
• a second pressing member arranged, opposing the first pressing member, and configured to cooperate with the first pressing member to press the sheet at the folding line;
• a first drive mechanism configured to move the first pressing member between a pressing position and a retreat position, thereby to cause the first pressing member to approach the second pressing member and, at the pressing position, to press the sheet at the folding line arranged between the first pressing member and the second pressing member, and to cause the first pressing member, at the retreat position, to move away from the sheet with respect to the second pressing member,
• a second drive mechanism configured to move the first pressing member along the folding line with respect to the second pressing member, after the first drive mechanism moves the first pressing member to the pressing position with respect to the second pressing member;
• and
• a restriction member configured to restrict, at a preset restriction position, the sheet thickness at the folding line to a value equal to or less than a prescribe value when the second drive mechanism starts moving the first pressing member along the folding line at the pressing position with respect to the second pressing member.