Rotary tablet press

Abstract

A rotary tablet press comprises a housing and a rotary die table having dies arranged circumferentially. Each die is associated with a punch having an end receivable in the die and being arranged for compression of a powder or granular material in the die by reciprocation of the punch by rotation of the die table. The rotary tablet press comprises a feeding device and a tablet discharge device. Each die opening and its corresponding punch end are enclosed in a compression chamber comprising a dust extraction nozzle. The compression chamber communicates with the surroundings of the tablet press through a non-return valve arranged to prevent outflow from the compression chamber to the surroundings of the tablet press.

1 . A rotary tablet press comprising a housing, a rotary die table having a number of dies arranged circumferentially, each die being associated with at least a first punch having a first end receivable in the die through an opening of the die and arranged for compression of a powder or granular material in the die by reciprocation of the punch, at least a cam for cooperation with a second end of the punches in order to effect axial displacement of the punches by rotation of the die table, a feeding device for the supply of material to be compressed into the dies, and a tablet discharge device for removal of compressed material in the form of tablets, wherein each die opening and its corresponding first punch end are enclosed in a compression chamber, said compression chamber comprising at least one dust extraction nozzle communicating with a dust extraction tube located outside the compression chamber, and said compression chamber communicating with the surroundings of the tablet press through a non-return valve arranged to prevent outflow from the compression chamber to the surroundings of the tablet press. 
   
   
       2 . A rotary tablet press according to  claim 1 , wherein the valve comprises a valve flap and a valve seat facing the inside of the compression chamber, and wherein the valve flap is biased against the valve seat. 
   
   
       3 . A rotary tablet press according to  claim 2 , wherein the valve seat is concave and the valve flap is made of flexible material. 
   
   
       4 . A rotary tablet press according to  claim 3 , wherein the valve flap is fixed on a shaft that is mounted axially displaceable in a central hole in the valve seat, and wherein the shaft is spring loaded to press the valve flap against the valve seat. 
   
   
       5 . A rotary tablet press according to  claim 3 , wherein the valve seat is circular and is provided with a plurality of through holes along its periphery. 
   
   
       6 . A rotary tablet press according to  claim 1 , wherein the compression chamber is delimited by a top wall in which the non-return valve is located, and wherein the non-return valve communicates with the surroundings of the tablet press through a vertical air intake duct. 
   
   
       7 . A rotary tablet press according to  claim 1 , wherein the compression chamber is comprised by a compression unit detachably mounted in the housing of the rotary tablet press, and wherein the non-return valve is located in wall of the compression unit. 
   
   
       8 . A rotary tablet press according to  claim 7 , wherein the compression unit is located in a compression section delimited by a upper partition wall and a lower partition wall of the housing of the rotary tablet press, and wherein a vertical air intake duct projects from the upper side of the upper partition wall in order to enable air to enter the compression section from the surroundings of the tablet press. 
   
   
       9 . A rotary tablet press according to  claim 8 , wherein the non-return valve is detachably connected with the vertical air intake duct by means of a vertically arranged connection piece. 
   
   
       10 . A rotary tablet press according to  claim 8 , wherein the non-return valve is detachably connected with the vertical air intake duct by means of a flexible tube. 
   
   
       11 . A rotary tablet press comprising a housing, a rotary die table having a number of dies arranged circumferentially, each die being associated with at least a first punch having a first end receivable in the die through an opening of the die and arranged for compression of a powder or granular material in the die by reciprocation of the punch, at least a cam for cooperation with a second end of the punches in order to effect axial displacement of the punches by rotation of the die table, a feeding device for the supply of material to be compressed into the dies, and a tablet discharge device for removal of compressed material in the form of tablets, wherein each die opening and its corresponding first punch end are enclosed in a compression chamber, said compression chamber comprising at least one dust extraction nozzle communicating with a dust extraction tube located outside the compression chamber, and said compression chamber communicating with the surroundings of the tablet press through a pressure controlled valve adapted to open, when the pressure inside the compression chamber is smaller than the pressure at the surroundings of the tablet press, and adapted to close, when the pressure inside the compression chamber is larger than the pressure at the surroundings of the tablet press. 
   
   
       12 . A rotary tablet press according to  claim 11 , wherein the pressure controlled valve comprises a valve element that is biased against a valve seat. 
   
   
       13 . A rotary tablet press according to  claim 11 , wherein the pressure controlled valve is controlled by a computer on the basis of a signal provided by a pressure transducer. 
   
   
       14 . A rotary tablet press according to  claim 11 , wherein the compression chamber is delimited by a top wall in which the non-return valve is located, and wherein the non-return valve communicates with the surroundings of the tablet press through a vertical air intake duct. 
   
   
       15 . A rotary tablet press according to  claim 11 , wherein the compression chamber is comprised by a compression unit detachably mounted in the housing of the rotary tablet press, and wherein the non-return valve is located in wall of the compression unit. 
   
   
       16 . A rotary tablet press according to  claim 15 , wherein the compression unit is located in a compression section delimited by a upper partition wall and a lower partition wall of the housing of the rotary tablet press, and wherein a vertical air intake duct projects from the upper side of the upper partition wall in order to enable air to enter the compression section from the surroundings of the tablet press. 
   
   
       17 . A rotary tablet press according to  claim 16 , wherein the non-return valve is detachably connected with the vertical air intake duct by means of a vertically arranged connection piece. 
   
   
       18 . A rotary tablet press according to  claim 16 , wherein the non-return valve is detachably connected with the vertical air intake duct by means of a flexible tube. 
   
   
       19 . A rotary tablet press comprising a housing, a rotary die table having a number of dies arranged circumferentially, each die being associated with at least a first punch having a first end receivable in the die through an opening of the die and arranged for compression of a powder or granular material in the die by reciprocation of the punch, at least a cam for cooperation with a second end of the punches in order to effect axial displacement of the punches by rotation of the die table, a feeding device for the supply of material to be compressed into the dies, and a tablet discharge device for removal of compressed material in the form of tablets, wherein each die opening and its corresponding first punch end are enclosed in a compression chamber, said compression chamber comprising at least one dust extraction nozzle communicating with a dust extraction tube located outside the compression chamber, said compression chamber communicating with the surroundings of the tablet press through a valve comprising a valve flap made of a material that is impervious to dust and a valve seat facing the inside of the compression chamber, and the valve flap being biased against the valve seat. 
   
   
       20 . A rotary tablet press according to  claim 19 , wherein the valve flap is made of a filter material. 
   
   
       21 . A rotary tablet press according to  claim 19 , wherein the compression chamber is delimited by a top wall in which the non-return valve is located, and wherein the non-return valve communicates with the surroundings of the tablet press through a vertical air intake duct. 
   
   
       22 . A rotary tablet press according to  claim 19 , wherein the compression chamber is comprised by a compression unit detachably mounted in the housing of the rotary tablet press, and wherein the non-return valve is located in wall of the compression unit. 
   
   
       23 . A rotary tablet press according to  claim 22 , wherein the compression unit is located in a compression section delimited by a upper partition wall and a lower partition wall of the housing of the rotary tablet press, and wherein a vertical air intake duct projects from the upper side of the upper partition wall in order to enable air to enter the compression section from the surroundings of the tablet press. 
   
   
       24 . A rotary tablet press according to  claim 23 , wherein the non-return valve is detachably connected with the vertical air intake duct by means of a vertically arranged connection piece. 
   
   
       25 . A rotary tablet press according to  claim 23 , wherein the non-return valve is detachably connected with the vertical air intake duct by means of a flexible tube.