Patent ID: 9617107
Date: 2017-04-11
CPC Classifications: B41F,B65H

Claim:
1. A web guiding or sheet guiding machine, in which webs or sheets are conveyed along a transport path (z), comprising: a first roller and a second roller, with at least one of the first roller and the second roller being drivable by an electric drive, the electric drive having associated therewith a power controller, with a roller nip bounded by the first roller and the second roller; and a safety device to monitor at least one of whether foreign bodies are penetrating into the roller nip and whether a specified torque for the electric drive is being maintained, the safety device including (i) a first measuring device to monitor an electrical variable of power made available to the electric drive by the power controller, (ii) a second measuring device to measure a physical variable having a functional relationship with the electrical variable, and (iii) a computer module to compare time sequences of the electrical variable and the physical variable with each other, and, based on any deviations in the compared time sequences, to generate alarm signals, the first measuring device monitoring a torque-forming current, and the second measuring device monitoring the physical variable, with the physical variable being selected from at least one of a tension and a speed associated with the conveyed webs or sheets, and, based on the measured values of the second measuring device, monitoring a correct function of the first measuring device, with the electrical variable of the power monitored by the first measuring device serving as a basis for an alarm signal that initiates an emergency interruption in operation of the web guiding or sheet guiding machine, and with a time interval between a transmission of monitored values of the second measuring device being substantially greater than a time interval between a transmission of monitored values of the first measuring device.