Sheet processing device, sheet laminator, image forming apparatus, and image forming system

A sheet processing device comprising:

• a rotator to wind a two-ply sheet, in which two sheets are overlapped and bonded at one end of the two-ply sheet, around the rotator to generate a winding circumferential difference between the two sheets of the two-ply sheet;
• a first nipper to nip the two-ply sheet with the rotator to convey the two-ply sheet in a conveyance direction;
• a conveyor disposed downstream from the rotator in the conveyance direction to convey the two-ply sheet to a nip between the rotator and the first nipper;
• a second nipper to nip the two-ply sheet with the rotator, the second nipper disposed downstream from the first nipper in a first rotational direction in which the rotator winds the two-ply sheet;
• a detector to detect an abnormal condition, in which a gap greater than a given interval is not formed between the two sheets of the two-ply sheet when the two sheets is wound around the rotator;
• and
• a memory to store a detection result as the abnormal condition by the detector,
• circuitry configured to:
• increase a nipping force of the second nipper, to nip the two-ply sheet with the rotator, with respect to the first nipper toward downstream from the first nipper in the first rotational direction;
• and
• increase the nipping force of the second nipper in a present sheet processing to be greater than a previous nipping force of the second nipper in a previous sheet processing when the memory stores the detection result as the abnormal condition in the previous sheet processing,
• to wind the two sheets of the two-ply sheet around the rotator.