Apparatus and method for manufacturing raw rubber strip

Abstract

An apparatus for intermittently manufacturing a raw rubber strip comprises a screw extruder, an extruder head having a preforming nozzle, a gear pump therebetween, a pair of calender rolls, a roll-gap changer for switching between a close state and an open state of calender rolls, and a controller for controlling the gear pump, the calender rolls and the roll-gap changer to let the calender rolls in the open state prior to the stopping of the rotation of the calender rolls.

1 . An apparatus for intermittently manufacturing a raw rubber strip, comprising a rubber extruder unit, a calender unit disposed in front of the rubber extruder unit, and a controller,
 the rubber extruder unit comprising: a screw extruder; an extruder head disposed at a front end of the rubber extruder unit; and a gear pump therebetween,   the screw extruder comprising: an extruder screw for kneading rubber materials supplied and pushing the kneaded rubber materials towards its outlet at the front end thereof,   the extruder head comprising: a nozzle block having a preforming nozzle for preforming the rubber extruded therefrom,   the gear pump having gears and positioned between the preforming nozzle and said outlet of the screw extruder so that, corresponding to on/off of the rotation of the gears, the rubber received from the outlet of the screw extruder is intermittently extruded from the preforming nozzle,   the calender unit comprising: a calender disposed in front of the extruder head; and a roll-gap changer,   the calender comprising: a pair of calender rolls at least one of which is driven to rotate and between which the preformed rubber extruded from the preforming nozzle is roll shaped into the row rubber strip having a finished thickness,   the roll-gap changer switches between a close state in which the calender rolls come close to each other in order to make the roll shaping and an open state in which the calender rolls get away from each other not to make the roll shaping,   the controller controls the rotation of the gears of the gear pump, the rotation of the calender rolls of the calender, and the switching of the roll-gap changer to let the calender rolls in the open state prior to the stopping of the rotation of the calender rolls.   
     
     
         2 . The apparatus according to  claim 1 , wherein
 the controller lets the calender rolls in the close state after the starting of the rotation of the calender roll.   
     
     
         3 . The apparatus according to  claim 1  or  2 , wherein
 the calender rolls has: a constant rotating speed state; an accelerating state from the starting of the rotation of the calender rolls to a constant rotating speed state; and a slowing-down state from the constant rotating speed state to the stopping of the rotation, 
 the gear pump has: a constant rotating speed state; an accelerating state from the starting of the rotation of the gears to the a constant rotating speed state; and a slowing-down state from the constant rotating speed state to the stopping of the rotation, and 
 the controller lets the time period t 2   c  of the slowing-down state of the calender rolls shorter than the time period t 2   g  of the slowing-down state of the gear pump. 
 
     
     
         4 . The apparatus according to  claim 3 , wherein
 by the controller, the starting of the rotation of the calender rolls is delayed from the starting of the rotation of the gear pump, and the starting of the slowing-down state of the calender rolls is delayed from the starting of the slowing-down state of the gear pump.   
     
     
         5 . A method for intermittently manufacturing a raw rubber strip by the use of the apparatus according to  claim 1 , in which
 the roll-gap changer is operated to let the calender rolls in the open state prior to the stopping of the rotation of the calender rolls.   
     
     
         6 . The method according to  claim 5 , wherein
 the roll-gap changer is operated to let the calender rolls in the close state with a time delay from the starting of rotation of the calender rolls.   
     
     
         7 . The method according to  claim 5  or  6 , wherein
 the calender rolls have: a constant rotating speed state; an accelerating state from the starting of the rotation of the calender rolls to the constant rotating speed state; and 
 a slowing-down state from the constant rotating speed state to the stopping of the rotation, 
 the gear pump has: a constant rotating speed state; an accelerating state from the starting of the rotation of the gears to the constant rotating speed state; and a slowing-down state from the constant rotating speed state to the stopping of the rotation, and 
 the time period t 2   c  of the slowing-down state of the calender rolls is controlled to be shorter than the time period t 2   g  of the slowing-down state of the gear pump. 
 
     
     
         8 . The method according to  claim 7 , wherein
 the starting of the rotation of the calender rolls is delayed from the starting of the rotation of the gear pump, and   the starting of the slowing-down state of the calender rolls is delayed from the starting of the slowing-down state of the gear pump.