Method and apparatus for controlling dynamic instability in axially moving form

摘要

A method and apparatus for controlling induced dynamic instability in an axially moving form by establishing a datum axis, repeatedly sensing the lateral position of the form in at least two mutually inclined transverse directions, deriving signals proportional to the sensed lateral displacement of the form from the datum axis, converting the signals to thrust forces, and applying the thrust forces to restore the form to the desired lateral position. The technique is of particular value in the production of oriented polymeric tubular films.