Web guiding system

In a system for guiding a moving, continuous web of sheet material, the combination comprising

• position scanner means including at least one sensor positioned along an edge of said sheet material for producing a position error signal which varies in accordance with deviations in web travel from a predetermined path,
• web shifting means responsive to said position error signal for automatically correcting the deviation of said web travel in a direction which tends to eliminate said position error signal,
• manual control means for enabling the operator to assume manual control of said web shifting means, including means for disabling said scanner means during manual control, and
• failure detector means associated with said scanner means for automatically disabling said scanner means and enabling said manual control means in response to a failure of said sensor.

In a system for guiding a moving, continuous web of sheet material, the combination comprising

• web shifting means operative between predetermined lateral limits for altering the web travel path,
• automatic position control means selectively coupled to said shifting means for monitoring the actual web position relative to a predetermined path and controlling said web shifting means to maintain the web travel along said predetermined path,
• manual position control means selectively coupled to said web shifting means for controlling the web travel along a manually selected path, and
• means associated with said web shifting means for disabling said automatic position control means and enabling said manual control means upon the attainment either of said predetermined lateral limits by said web shifting means.

In combination, a position sensing mechanism for controlling the course of a continuous web of material through a press comprising

• a source of radiation in the infrared range,
• focus means for guiding said radiation into a channel having a width encompassing the range of normal web edge deviation from a desired path, and
• signal means spaced from said focus means for receiving said radiation and producing a continuous output signal corresponding to the magnitude of said radiation passing the edge of the continuous web as the web moves through the channel, and
• monitoring means connected to the position sensing mechanism for continuously measuring the position of the web along the desired path.

A web control assembly for a web comprising an entrance roller,

• a tilt frame having a pair of tilt rollers mounted thereon,
• an exit roller,
• said web being disposed under the entrance roller, over the tilt rollers and under the exit roller,
• a motor means connected to the tilt frame operable to move the frame to cant the tilt rollers with respect to the longitudinal line of travel of the web,
• a web edge scanner adjacent at least one edge of the web,
• said scanner including
• a source of radiation in the infrared range,
• focus means for guiding said radiation into a channel having a width encompassing the range of normal web edge deviation from a desired path along said longitudinal line of travel, and
• signal means spaced from said focus means for receiving said radiation and producing a continuous output signal corresponding to the magnitude of said radiation passing the edge of the web, and
• means intermediate the motor means and the scanner for directing the motor means to cant and straighten the tilt frame.

In a system for guiding a moving, continuous web of sheet material, the combination comprising

• an AC power source,
• web shifting means including at least one tilt roller and a variable speed motor for controlling said roller so as to effect a lateral shift in the web path, said motor having a first winding coupled to said AC source and a second winding which changes position relative to said first winding with rotation of said motor and is controllable for varying the direction and speed of the motor,
• command means for developing a command signal whose polarity corresponds to a desired direction of travel for said motor and whose magnitude corresponds to a desired speed for said motor,
• signal processing means coupled to said AC power source, said command means and said web shifting means for (a) developing a first pulse train in phase with the positive half cycle of said AC power source having a pulse width corresponding to the magnitude of said command signal and for applying said first pulse train to the second winding of said motor whenever said command signal is of a first polarity so as to drive said motor in one direction, the firing angle of said motor corresponding to the pulse width of said first pulse train and (b) developing a second pulse train in phase with the negative half cycle of said AC power source having a pulse width corresponding to the magnitude of said command signal and for applying said second pulse train to the second winding of said motor whenever said command signal is of the opposite polarity so as to drive said motor in the opposite direction with a firing angle corresponding to the pulse width of said second pulse train.

In a system for guiding a moving, continuous web of sheet material, the combination comprising

• an AC power source,
• means for laterally shifting the web in relation to its path of travel,
• a motor supplied by said AC power source and having at least one control winding for varying the speed and direction of said motor in accordance with the duty cycle and direction of an applied current,
• means for developing a command signal corresponding in magnitude and polarity to the desired speed and direction of travel for said motor, and
• means responsive to said command signal for developing a current pulse train on said control winding which is in phase with said AC source and which has a direction and duty cycle corresponding respectively to the polarity and magnitude of said command signal.