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Control for batch mixers

  • US 4,818,113 A
  • Filed: 04/24/1987
  • Issued: 04/04/1989
  • Est. Priority Date: 04/26/1986
  • Status: Expired due to Fees
First Claim
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1. A process for mixing a composition comprising polymeric material and additive materials in an internal mixer having two mixing rotors mounted for rotation in a mixing chamber, a ram mounted for sliding movement in a passage opening into the mixing chamber by which pressure can be applied to material in the mixing chamber, and means for controlling the temperature of the mixer, the process comprising:

  • (a) rotating the rotors at a preselected rate;

    (b) introducing each of the polymeric and additive materials to be mixed into the mixing chamber at appropriate intervals after start of the mixing operation;

    (c) applying a preselected pressure to the ram; and

    (d) after all of the materials to be mixed have been added, initiating a control stage when the ram has reached a predetermined position of the ram in the passage, the control stage comprising;

    (1) selecting defined ultimate targets from at least some monitorable mixing variables at which mixing is deemed satisfactory, said mixing variables being selected from composition temperature, total energy input to the composition by the rotors during mixing, mixing cycle time, torque of the rotors at a preselected mixing cycle time and position of the ram;

    (2) monitoring said mixing variables from which the quality of mixing can be determined; and

    (3) dependent on the value of the mixing variables monitored, adjusting at least one control variable of the mixing process selected from rotor speed and ram pressure so that the mixing process continues towards the previously defined ultimate targets of the monitored mixing variables at which mixing is deemed satisfactory.

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