| 摘要 |
A method is provided for measuring and controlling a cumulative physical property, such as the thickness, of a tubular blown film, wherein the tubular blown film is being extruded from a ring-shaped extruder having a plurality of film physical property controllers disposed around the ring-shaped extruder. Where the physical property is thickness, the method includes the steps of (1) collapsing the tubular film to create a two-ply web and slowly rotating the film while taking a plurality of thickness measurements across the two-play web at various sections of the film, (2) calculating initial estimates of the thickness of each section using a first algorithm, (3) refining the initial estimates of the thicknesses of each section by successive iterations using a second algorithm, and (4) optionally adjusting at least one film physical property controller to control the final estimate of the thicknesses of each longitudinal section. |
