Sheet processing apparatus and image forming system incorporating the sheet processing apparatus

A sheet processing apparatus comprising:

• a sheet conveyor including pairs of conveyance rollers configured to convey a sheet at a conveyance speed in a conveyance direction;
• a processing tool configured to perform processing to the sheet, the processing tool being between the pairs of conveyance rollers in the conveyance direction of the sheet;
• a tool contact separation device configured to contact and separate the processing tool to the sheet;
• a tool moving device configured to move the processing tool in a direction intersecting the conveyance direction of the sheet;
• and
• a tool facing device including a facing roller having a tool facing portion disposed at a position facing the processing tool with the sheet interposed therebetween, the facing roller being drivable by a drive source;
• and
• a controller configured to determine whether a moving direction of the processing tool is orthogonal to the conveyance direction of the sheet, and to control the drive source to,
• set the facing roller to a first state by instructing the drive source to immobilize the facing roller such that the tool facing portion is immovable, when the controller determines that the moving direction of the processing tool with respect to the sheet is orthogonal to the conveyance direction of the sheet, and
• set the facing roller to a second state by instructing the drive source to rotate the facing roller in synchrony with conveyance of the sheet by the pairs of conveyance rollers such that the tool facing portion rotates at a same speed as the conveyance speed of the sheet, when the controller determines that the moving direction of the processing tool with respect to the sheet is not orthogonal to the conveyance direction of the sheet.