Method for control of the thickness of extruded film

Device for the automatic control of the thickness of the extruded film (8) having the following features:

• a thickness-measuring probe (12) for measuring the thickness profile of the film just extruded (8) that is moved along the surface of the film (8) substantially perpendicular (x) to the conveying direction (z) of the extruded film (8). The thickness measuring probe (12) records for each measuring cycle (MZ) a thickness profile (P) of the film (8) at least across parts of the expansion of the film (8) perpendicular (x) to its conveying direction (z),
• Transmitting the measured values to a control unit (14, 15, 17),
• A storage unit (14) for recording the measured values and the information derived therefrom,
• A computer (14) for providing statistical values of the film thickness (5) taking into account measured values or information derived therefrom using a definite number (N) of measuring cycles (MZ) and using which (14), if necessary, measured values from recent and older measuring cycles can be provided with different weighting factors,
• whereby even the deviations in the statistical values of the film thickness (5) from a target value can be determined using the computer (14),
• A device (17) for generating control commands to a device for controlling the film thickness (5)
• characterized in that
• while providing the statistical values in relation to the older measured values the latest measured value(s) from a predetermined time-frame at the start of the extrusion are heavily weighted using the computer (14) than during the normal operation.