Unwinder

Abstract

The present invention relates to an unwinder for a packaging machine, in particular for a thermoformer or tray sealer, comprising a holding mandrel provided for receiving thereon a film reel having a film wound thereon. The unwinder comprises a measuring module configured to detect a distance to an end face of the film wound on the film reel and/or a distance to a stop member.

What is claimed is: 
     
         1 . An unwinder for a packaging machine, in particular for a thermoformer or tray sealer, said unwinder comprising:
 a holding mandrel configured for receiving thereon a film reel having a film wound thereon; and   a measuring module configured to detect a distance to an end face of the film wound on the film reel and/or a distance to a stop member supported on the holding mandrel such that it is displaceable thereon in the axial direction of the holding mandrel.   
     
     
         2 . The unwinder of  claim 1  further comprising a housing and wherein the measuring module is mounted on or in the housing. 
     
     
         3 . The unwinder of  claim 2  wherein the measuring module is mounted between the housing and the film reel held by the holding mandrel. 
     
     
         4 . The unwinder of  claim 1 , wherein a measurement path established by the measuring module extends parallel to an axis of the holding mandrel. 
     
     
         5 . The unwinder of  claim 1 , wherein the holding mandrel includes a tensioning device provided for securing the film reel in position on the holding mandrel. 
     
     
         6 . The unwinder of  claim 1 , wherein the measuring module comprises at least one contactless sensor. 
     
     
         7 . The unwinder of  claim 1 , wherein the stop member is adapted to be locked in position on the holding mandrel. 
     
     
         8 . The unwinder of  claim 1 , wherein the measuring module is functionally connected to an operating panel of the packaging machine. 
     
     
         9 . A packaging machine comprising:
 an unwinder including:
 a holding mandrel configured for receiving thereon a film reel having a film wound thereon; and 
 a measuring module configured to detect a distance to an end face of the film wound on the film reel and/or a distance to a stop member supported on the holding mandrel such that it is displaceable thereon in the axial direction of the holding mandrel. 
   
     
     
         10 . The packaging machine of  claim 9  further comprising operating elements by means of which an exchange of the film reel can be controlled, the operating elements being configured for controlling release of the film reel from the holding mandrel or mounting of the film reel on the holding mandrel. 
     
     
         11 . The packaging machine of  claim 9  further comprising a control unit by means of which the distance measured by the measuring module can be detected as a measurement signal. 
     
     
         12 . The packaging machine of  claim 9  further comprising a memory in which the distance to the film, measured by the measuring module, can be stored. 
     
     
         13 . The packaging machine of  claim 12  further comprising a switch, which, when actuated, allows to store in the memory a nominal distance between the film or the stop member and the measuring module, especially when a film reel having specific dimensions is secured in position for the first time. 
     
     
         14 . The packaging machine of  claim 13 , wherein the packaging machine is configured for defining an admissible tolerance field around a nominal distance. 
     
     
         15 . The packaging machine of  claim 14 , wherein the packaging machine is configured for checking whether the measured distance to the film corresponds to a value of the defined tolerance field. 
     
     
         16 . The packaging machine of  claim 14 , wherein fixing the film reel in position on the holding mandrel can be executed, when the measured distance between the measuring module and the film or the stop member lies within the tolerance field. 
     
     
         17 . The packaging machine of  claim 9  further comprising a signaling unit, which is configured for outputting acoustically and/or visually a predetermined signal to an operator, and which is configured for indicating whether the film is correctly positioned on the holding mandrel.