Active modulation of the feed currents from drives to support machining processes through micro-vibrations and to dampen system vibrations with the help of a three-phase choke

摘要

The object of the invention is to modulate the current signals in a system consisting of a frequency converter and an electric motor in order to superimpose an oscillation on the rotary movement of a tool in a motor spindle and thus improve chip breaking in the machining process. In addition, the targeted damping of process-related vibrations can improve the processing quality. To solve the problem, a choke is provided between the frequency converter and the motor, which has an additional winding in addition to the primary winding. In previous arrangements, this winding is short-circuited via a resistor. This can dampen unwanted frequency components in the current signal. The innovation is that in the case of the described invention, signals are specifically applied to this winding by a separate feed unit. The current signals that reach the motor then represent a superposition of the fundamental wave of the frequency converter and the specified signal. One area of application is the machine tool. Here a torsional vibration can be superimposed on the rotary movement of the tool in the motor spindle. The periodic change in the conditions at the tool cutting edge results in improved chip breakage behavior, for example during circumferential milling. Previous methods, such as the use of piezoelectric ultrasonic actuators, did not have the desired effect here. The modulation of the signal also enables the machine's performance to be improved by correcting any deviations in the symmetry of the currents in the three phases.