Device for detecting paper splice part of cardboard sheet, and device for producing cardboard sheet

A paper splice part detection device of a cardboard sheet, which detects a sheet paper splice part in a cardboard sheet in which a first sheet, a corrugated second sheet, and a third sheet are bonded, the device comprising:

• a sheet paper splice detection unit disposed between a sheet paper splicing position and a sheet bonding position in a sheet transfer direction and detecting the sheet paper splice part, based on a shape of the sheet;
• a marking device that includes a crushing roller and is configured to assign a mark using the crushing roller to the sheet paper splice part on a downstream side in the sheet transfer direction from the sheet paper splice detection unit;
• and
• a mark detection device that detects the mark formed by the marking device on the cardboard sheet on the downstream side in the sheet transfer direction from the marking device,
• wherein the sheet paper splice detection unit is disposed between a dancer roll of a sheet paper splicing device and a preheater located upstream of a sheet bonding device forming a single-faced cardboard sheet laminates sheet.