Abstract: To facilitate permeation of water when water is applied to the crimping range of a sheet made of a water-permeable paper material. A binding unit applies water to placed sheets and then crimp-binds the sheets. The binding unit includes a pair of pressure teeth (pressure teeth and receiving teeth part) provided on both the front and back sides of the sheets and configured to crimp-binding the sheets, a water reservoir provided on the back surface side of any one of the pressure teeth and configured to store water to be applied to the sheet, and a pressurizing member (piston) that pressurizes the water in the water reservoir to apply water to the sheet crimping range.

Abstract: To facilitate permeation of water when water is applied to the crimping range of a sheet made of a water-permeable paper material. A binding unit applies water to placed sheets and then crimp-binds the sheets. The binding unit includes a pair of pressure teeth (pressure teeth and receiving teeth part) provided on both the front and back sides of the sheets and configured to crimp-binding the sheets, a water reservoir provided on the back surface side of any one of the pressure teeth and configured to store water to be applied to the sheet, and a pressurizing member (piston) that pressurizes the water in the water reservoir to apply water to the sheet crimping range.

Abstract: A sheet processing device has a binding unit that applies water to a crimping range of sheets and then crimps the sheets. The sheet processing device includes a processing tray on which sheets are placed, a pair of pressure teeth (pressure teeth and receiving teeth) that crimps the sheets placed on the processing tray at a crimping position with the sheets interposed therebetween, and a water application member (cylinder and piston) that applies water to the crimping position before crimping by the pressure teeth. When the number of sheets placed on the processing tray is equal to or less than a predetermined number, the sheets are crimped by the pressure teeth without water application; while when the number of sheets placed on the processing tray exceeds the predetermined number, the sheets are crimped by the pressure teeth after water application.