An internal mixer and controller enables the phase difference and the speed ratio between two rotors to be changed without stopping the operation of the mixer. The internal mixer comprises: nonintermeshed first and second rotors disposed in a mixing chamber; first and second drive units; first and second phase measuring devices; first and second speed measuring devices; and a control unit for controlling the first and second drive units on the basis of signals from the first and second speed measuring devices and signals from the first and second phase measuring devices. The control unit controls the two rotors so as to synchronously rotate at the same speed on the basis of the signals from the speed measuring devices when the two rotors fixedly rotate at the same speed. When the phase difference between the two rotors is changed, the control unit calculates the phase difference from the signals from the phase measuring devices, compares the calculated phase difference with a set phase difference, and controls the second drive unit to change the speed of the second rotor, thereby changing the phase. When the phase difference is equal to the set phase difference, the control unit again controls the two rotors so as to synchronously rotate at the same speed on the basis of the signals from the speed measuring devices. When the two rotors are rotated at different speeds, the control unit controls the drive units so that the speed of each of the rotors is equal to the set speed, respectively, on the basis of the measured speed from speed measuring devices.
The invention concerns a process and a device for the recognition of screws used in extruders or metering devices. In order to create a process that excludes the possibility that mixtures of granulates or powders with incorrect mixing ratios occur through installation of inappropriate screw shafts in metering screws, the screws are coded and the code is electronically identifiable.
