An image forming apparatus to which a first feeding device which does not notify abnormal sheet feeding or a second feeding device which notifies the abnormal sheet feeding is connectable includes a sheet receiving portion, a sheet detector, an image forming unit, and a controller. In a case that the first feeding device is connected to the image forming apparatus, the controller discriminates that the abnormal sheet feeding occurs in the first feeding device when the detector does not detect the sheet at first timing. In a case that the second feeding device is connected to the image forming apparatus, the controller discriminates that the abnormal sheet feeding occurs at the sheet receiving portion when the detector does not detect the sheet at second timing and notification of the abnormal sheet feeding is not provided from the second feeding device.

In order to provide a numbering and imprinting machine capable of minimizing the amount of wasted paper produced, the numbering and imprinting machine is provided with: a first-number inspection camera (124B) that is arranged downstream of the position of contact between an impression cylinder (112) and a first-number cylinder (113) of a first-number printing unit (111) in the direction of rotation of the impression cylinder (112), and images a first number printed on paper (W) held on the impression cylinder (112); a second number inspection camera (124C) that is arranged downstream of the position of contact between an impression cylinder (117) and a second-number cylinder (118) of a second-number printing unit (116) in the direction of rotation of the impression cylinder (117), and images a second number printed on paper (W) held on the impression cylinder (117); and a printing-press control device (10) that controls first- and second-number-cylinder throw-on and throw-off devices (38, 39) based on signals from the first- and second-number inspection cameras (124B, 124C) to cause the first-number cylinder (113) and the second-number cylinder (118) to make separating movements.

A coating unit is located after a sheet-fed digital printer on a manufacturing line. As a response to a workpiece entering the coating unit from the printer, coating substance is dosed onto a plate cylinder, and said plate cylinder is rotated to transfer said coating substance onto the workpiece, which is then transferred further on the manufacturing line. As a response to a first time limit expiring after transferring the workpiece further without a subsequent workpiece entering the coating unit, the rotation of the plate cylinder is stopped.

A coating unit is located after a sheet-fed digital printer on a manufacturing line. As a response to a workpiece entering the coating unit from the printer, coating substance is dosed onto a plate cylinder, and said plate cylinder is rotated to transfer said coating substance onto the workpiece, which is then transferred further on the manufacturing line. As a response to a first time limit expiring after transferring the workpiece further without a subsequent workpiece entering the coating unit, the rotation of the plate cylinder is stopped.