Abstract: A method for dynamically controlling a driver of a nip roller in a web printing press includes controlling the speed of the driver in a tension-control mode during a phase of printing press operation and in a velocity-control mode during another phase of printing press operation. The controlling of the speed of the driver in the tension-control mode is based on the tension in the web upstream of the nip roller so as to maintain the tension at a desired tension value. The controlling of the speed of the driver in the velocity-control mode is based on a predetermined driver velocity ratio for maintaining the web tension. The tension-control mode may be employed during press start-up as the web accelerates to operating speed. The velocity-control mode may be used during printing operations of the press.

Abstract: A method for determining the presence of slipping of a driven nip roller relative to the web in a web printing press includes systematically changing the speed of the nip driver while monitoring the corresponding change in web tension difference across the nip. The linearity and a slope of the relationship between the tension difference and the speed of the nip driver are determined. When the tension difference is non-linear relative to the speed of the driver or the slope of the relationship is substantially less than an expected slope, then slipping is determined to be present. An operator slip indication may be provided which includes the direction of the slip, positive or negative. The operator may then take corrective action to re-establish a non-slip condition, or automatic corrective actions may ensue.

Abstract: A method for dynamically controlling a driver of a nip roller in a web printing press includes controlling the speed of the driver in a tension-control mode during a phase of printing press operation and in a velocity-control mode during another phase of printing press operation. The controlling of the speed of the driver in the tension-control mode is based on the tension in the web upstream of the nip roller so as to maintain the tension at a desired tension value. The controlling of the speed of the driver in the velocity-control mode is based on a predetermined driver velocity ratio for maintaining the web tension. The tension-control mode may be employed during press start-up as the web accelerates to operating speed. The velocity-control mode may be used during printing operations of the press.

Abstract: An apparatus for calibrating a tension transducer for a web includes a pair of nip rollers and a motor for driving at least one of the pair of nip rollers, the motor having at least one roller output being a function of at least one of a motor torque and a motor velocity. A web tension transducer roll is located upstream of the nip rollers, the web tension transducer having a tension output being a function of the actual web tension of the web. A processor receives the at least one roller output and the tension output, the processor calculating a tension correction value as a function of the at least one roller output and the tension output.

Abstract: An apparatus for calibrating a tension transducer for a web includes a pair of nip rollers and a motor for driving at least one of the pair of nip rollers, the motor having at least one roller output being a function of at least one of a motor torque and a motor velocity. A web tension transducer roll is located upstream of the nip rollers, the web tension transducer having a tension output being a function of the actual web tension of the web. A processor receives the at least one roller output and the tension output, the processor calculating a tension correction value as a function of the at least one roller output and the tension output.

Abstract: A web tension measurement device includes a roller for a web of material, the movable roller having an axis of rotation moveable in a first direction by the web; a counteracting device connected to the movable roller, the counteracting device for forcing the axis of the roller in a second direction opposite the first direction; and a controller connected to the counteracting device for measuring the web tension. Also included is a method for measuring tension in a web which comprises the steps of running a web over a roller, an axis of the roller being movable in a first direction, counteracting the movement of the roller in a second direction opposite the first direction, and measuring a counteracting force or a variable so as to be able to determine a web tension.