Apparatus for sealing a cover foil to a blister foil

Abstract

A cover foil is sealed to a foil formed with an array of blisters by a drive roller centered on an axis and having a generally cylindrical outer surface formed with an array of outwardly open recesses complementary to the array of blisters. The outer surface is annularly continuous and formed of an at least limitedly elastically deformable material. The roller further is formed inward of the outer surface with at least one pressurizable chamber. The blister foil engages the drive roller with the blisters fitting into the recesses. A sealing roller presses a cover foil radially against the blister foil on the drive roller and thereby seals the cover foil to the blister foil between the blisters. A source of compressed air is connected to the drive roller for pressurizing the chamber and thereby changing a circumference of the drive-roller outer surface and an angular spacing between the recesses.

1 . An apparatus for sealing a cover foil to a foil formed with an array of blisters, the apparatus comprising: 
 a drive roller centered on an axis and having a generally cylindrical outer surface formed with an array of outwardly open recesses complementary to the array of blisters, the outer surface being annularly continuous and formed of an at least limitedly elastically deformable material, the roller further being formed inward of the outer surface with at least one pressurizable chamber, the blister foil engaging the drive roller with the blisters fitting into the recesses;    means for rotating the drive roller about the axis and thereby advancing the blister foil;    means including a sealing roller for pressing a cover foil radially against the blister foil on the drive roller and sealing the cover foil to the blister foil between the blisters; and    means connected to the drive roller for pressurizing the chamber and thereby changing a circumference of the drive-roller outer surface and an angular spacing between the recesses.    
     
     
         2 . The sealing apparatus defined in  claim 1 , further comprising: 
 sensor means upstream of the drive roller for detecting a spacing between the blisters of the blister foil; and    control means connected to the sensor means and to the pressurizing means for adjusting the pressurization of the chamber such that the spacing of the recesses is substantially equal to the detected spacing of the blisters.    
     
     
         3 . The sealing apparatus defined in  claim 1  wherein the surface is made of a material having a smaller modulus of elasticity than metal.  
     
     
         4 . The sealing apparatus defined in  claim 3  wherein the material is plastic.  
     
     
         5 . The sealing apparatus defined in  claim 4  wherein the material is polytetrafluoroethylene.  
     
     
         6 . The sealing apparatus defined in  claim 4  wherein the material is a polyamide.  
     
     
         7 . The sealing apparatus defined in  claim 3  wherein the surface is formed by a tubularly cylindrical sheath.  
     
     
         8 . The sealing apparatus defined in  claim 7  wherein the drive roller is formed with a plurality of the chambers angularly spaced about the axis.  
     
     
         9 . The sealing apparatus defined in  claim 8  wherein the drive roller has a hub radially inwardly delimiting the chambers and spokes angularly delimiting the chambers and connected to the sheath.  
     
     
         10 . The sealing apparatus defined in  claim 9  wherein the hub, spokes, and sheath are unitary.  
     
     
         11 . The sealing apparatus defined in  claim 9  wherein the drive roller has a pair of axially spaced face disks axially delimiting the chambers.  
     
     
         12 . The sealing apparatus defined in  claim 11  wherein the disks are generally planar and have outer diameters smaller than an outer diameter of the sheath.  
     
     
         13 . The sealing apparatus defined in  claim 11  wherein the drive means further comprises axially extending bolts having ends pressing the disks against the hub, spokes, and sheath.  
     
     
         14 . The sealing apparatus defined in  claim 13  wherein one such bolt extends axially through each chamber.  
     
     
         15 . The sealing apparatus defined in  claim 1  wherein the drive roller has a shaft and the means for pressurizing includes a coupling connected to the shaft.  
     
     
         16 . The sealing apparatus defined in  claim 1 , further comprising 
 sensor means for detecting a temperature of the sealing roller.    
     
     
         17 . The sealing apparatus defined in  claim 1  wherein the pressurizing means include valve means for varying the pressurization of the chamber.  
     
     
         18 . The sealing apparatus defined in  claim 1 , further comprising 
 means for detecting the presence of the foils between the rollers.    
     
     
         19 . The sealing apparatus defined in  claim 1  wherein the means for pressurizing pumps air into the chamber.  
     
     
         20 . The sealing apparatus defined in  claim 1  wherein the chamber is so constructed that when it is pressurized only its outer diameter changes.