Method and system for registering pre-produced webs with variable pitch length

A method for registering an off-line produced web having pre-produced objects longitudinally spaced at a pitch interval to a converting line manufacturing disposable absorbent articles, such as diapers, pants, feminine hygiene articles, and the like, or a component of a disposable absorbent article, the off-line produced web being manipulated as a controlled web in order for the pre-produced object of the controlled web to be registered in relation to a target position constant and in phase automatically with the pitched unit operation, the method comprising the steps of:

• a. providing a controlled web having pre-produced objects spaced at a controlled pitch interval, at a controlled velocity in a machine direction;
• b. providing an actual position data of the pre-produced object by detecting the pre-produced object by a sensor;
• c. providing the target position constant at a desired position within a manufacturing cycle of a pitched unit operation;
• d. generating a correction signal based upon the actual position data and the target position constant;
• e. adjusting the control velocity of the control web in order to register the pre-produced object of the controlled web in relation to the target position constant;
• and
• f. coupling the pitched unit operation with a controlled web metering point by providing a converter position reference signal fed forward from the pitched unit operation functioning as an independent axis to the controlled web metering point functioning as a dependent axis in order for the pre-produced object of the controlled web be in phase automatically with the pitched unit operation.

A method for registering an off-line produced web having pre-produced objects longitudinally spaced at a pitch interval to a converting line manufacturing disposable absorbent articles, such as diapers, pants, feminine hygiene articles, and the like, or a component of a disposable absorbent article, the off-line produced web being manipulated as a controlled web in order for the pre-produced object of the controlled web to be registered in relation to a target bias position constant and in phase automatically with the pitched unit operation, the method comprising the steps of:

• a. providing a controlled web having pre-produced objects spaced at a controlled pitch interval, at a controlled velocity in a machine direction;
• b. providing an actual bias position data based upon the captured production images of the pre-produced objects of the controlled web and comparing the captured production images to one or more stored reference images by a machine vision system;
• c. providing the target bias position constant at a desired position within a manufacturing cycle of the pitched unit operation;
• d. generating a correction signal based upon the actual bias position data and the target bias position constant;
• e. adjusting the controlled velocity of the controlled web in order to register the pre-produced object of the controlled web in relation to the target bias position constant;
• and
• f. coupling the pitched unit operation with a controlled web metering point by providing a converter position reference signal fed forward from the pitched unit operation functioning as an independent axis to the controlled web metering point functioning as a dependent axis in order for the pre-produced object of the controlled web be in phase automatically with the pitched unit operation.

A system for registering an off-line produced web having pre-produced objects longitudinally spaced at a pitch interval to a converting line manufacturing disposable absorbent articles, such as diapers, pants, feminine hygiene articles, and the like, or a component of a disposable absorbent article, the system comprising:

• a. a web metering point for providing a controlled web having pre-produced objects spaced at a controlled pitch interval moving in the machine direction at a controlled velocity in a machine direction,
• b. a sensor disposed adjacent the controlled web for providing an actual position data of the pre-produced object on the controlled web by detecting the pre-produced object within a manufacturing cycle of the pitched unit operation;
• c. a product detection stage for providing the target position constant at a desired position within the manufacturing cycle of the pitched unit operation;
• and
• d. a controller for generating a correction signal based upon the actual position data and the target position constant and for adjusting the control velocity of the control web in order to register the pre-produced object of the controlled web in relation to the target position constant,
• wherein the correction signal is calculated according to a formula
• μ=Kp*error+Ki*Σerror*ΔT
• wherein
• μis the correction signal,
• Kp is a proportinal gain,
• Ki is a integral gain,
• error is an error signal, and
• ΔT is a time period between consecutive calculations.