Tool drive having a spindle shaft and operating method

Operating method for a tool drive with a spindle shaft, the tool drive with the spindle shaft comprising

• at least one electromagnetic axial actuator,
• a control and/or regulation apparatus for the operation of the axial actuator for changing the position of the spindle shaft along the longitudinal axis,
• wherein the control and/or regulation apparatus is configured to drive the axial actuator for the generation of microvibration movement of the spindle shaft,
• the method comprising
• superimposing, through the at least axial actuator and the control and/or regulation apparatus an adjustable axial microvibration movement of the spindle shaft, independently of and superimposed on a feed movement, in order to influence the chip size and chip shape of the material removed from holes during a drilling process,
• using at least one axial magnetic bearing and/or one linear motor as the axial actuator for generating axial microvibration movements,
• choosing a setpoint oscillation curve of the axial microvibration movement depending on directly or indirectly determinable drilling parameters,
• adjusting the axial microvibration movement during a drilling process, and
• specifying, via a setpoint value curve of the microvibration movement, a lower feed rate at or before contact of the tool on the workpiece.