Abstract: A package sensing system provides length, width and height signals to a film control system which selects the width and length of stretch film to be used by a film wrapping machine to wrap the sensed package. Package width is sensed by spring biased swing arms which active electrical switches upon deflection by an entering package. A wide package is indicated if both swing arms are deflected. The length and height of a package are sensed by a generally vertical downwardly extending lever arm which is pivotally mounted above the package entryway into the machine. A first electrical switch coupled to the lever arm generates a length signal upon initial contact by an entering package and a second electrical switch coupled to the lever arm generates a height signal depending upon the ultimate deflection of the lever arm by the package.

Abstract: In a stretch film wrapping machine an improved control system provides for automatic or manual selection of one of at least two differing width film rolls and provides individualized wrapping parameters dependent upon the film width selected. Automatic film selection is performed in response to signals identifying the height, width and length of a package to be wrapped which characteristics are sensed or measured by a package sensing system. Both automatic and manual film selection includes timing controls for synchronizing film gripping and clamping apparatus with underfolding apparatus dependent upon the film selected to provide improved control over the tensioning of film wrapped about individual packages.

Abstract: In a film wrapping machine for wrapping packages in stretchable film, a monitoring system is provided to generate a signal each time film is drawn into the machine. If no film is drawn into the machine indicating that the film source has expired, broken or otherwise become disengaged from the film feeding apparatus for the wrapping machine, the machine is stopped. The film draw into the machine is monitored by an electrical switch which is coupled to a tensioning roller, the motion of which is adjusted to activate the switch each time even at least a minimum length of film is drawn into the machine.