Tray sealer

Abstract

A tray sealer that includes a control unit and a sealing station is presented. The sealing station comprises a tool upper part, a clamping frame and a tool lower part. The interior of the tool upper part comprises a dome-shaped die for deforming a top film. The dome-shaped die comprises at least a first channel and the tool upper part comprises a second channel. The dome-shaped die may have an inner contact surface. The clamping frame may clamp the top film in position on the tool upper part in a gas-tight manner so as to define an upper chamber within the tool upper part. In one embodiment, a vacuum sensor is operably connected to the control unit and is disposed between the dome-shaped die and a vacuum generator. The control unit may detect a tear in the film using a pressure profile generated by the vacuum sensor.

What is claimed is: 
     
         1 . A tray sealer including a control unit and a sealing station, the tray sealer comprises:
 a tool upper part;   a clamping frame; and   a tool lower part;   wherein the interior of the tool upper part has arranged therein a dome-shaped die for deforming a top film;   wherein the dome-shaped die comprises at least a first channel, and the tool upper part comprises a second channel;   wherein the dome-shaped die has an inner contact surface; and   wherein the clamping frame is disposed to clamp the top film in position on the tool upper part in a gas-tight manner so as to define an upper chamber within the tool upper part; and   wherein a vacuum sensor is operably connected to the control unit and the vacuum sensor is disposed between the dome-shaped die and a vacuum generator to generate a pressure profile during a sealing operation, the control unit being operable to detect a tear in the top film on the basis of the pressure profile.   
     
     
         2 . The tray sealer according to  claim 1 , wherein the dome-shaped die comprises a plurality of venting ducts. 
     
     
         3 . The tray sealer according to  claim 1 , wherein the dome-shaped die has a sealing surface. 
     
     
         4 . The tray sealer according to  claim 3 , wherein the dome-shaped die is movable between an upper position for deforming the top film and a lower position for sealing the top film onto a tray edge of at least one tray. 
     
     
         5 . The tray sealer according to  claim 1 , further comprising a seal disposed at a transition of the first channel from the dome-shaped die to the second channel of the tool upper part. 
     
     
         6 . A method of operating a tray sealer, wherein the tray sealer includes a control unit and a sealing station, the sealing station comprising a tool upper part, a clamping frame and a tool lower part, wherein the tool upper part receives therein a dome-shaped die for deforming a top film, wherein the dome-shaped die comprises at least a first channel, wherein the tool upper part comprises a second channel, wherein the dome-shaped die has an inner contact surface, and wherein the clamping frame is configured to clamp the top film in position on the tool upper part in a gas-tight manner so as to define a chamber within the tool upper part, the method comprising:
 measuring a negative pressure using a vacuum sensor disposed between the dome-shaped die and a vacuum generator;   generating a pressure profile based upon the measured negative pressure; and   detecting a tear in the film based upon the pressure profile using the control unit.   
     
     
         7 . The method according to  claim 6 , further comprising displaying a message using the control panel when a tear in the film is detected. 
     
     
         8 . The method according to  claim 6 , further comprising one of (a) not starting a sealing process or (b) discontinuing a sealing process when a tear in the film is detected using the control unit. 
     
     
         9 . The method according to  claim 6 , further comprising the steps of:
 supplying air to the upper tool part after a tear in the film is detected;   advancing the top film in the conveying direction; and   thermoforming a subsequent section of the top film into the dome-shaped die after the advancing the top film step for sealing the tray.   
     
     
         10 . The method according to  claim 6 , further comprising: detecting that the top film is in contact with the inner contact surface of the dome-shaped die using the pressure profile.