Wear monitoring device and ball screw drive

A wear monitoring device for a succession of ferromagnetic rolling elements, the wear monitoring device comprising:

• at least one magnet for generating a measuring magnetic field;
• a magnetic field sensor arrangement for measuring a flux density of the measuring magnetic field, the magnetic field sensor arrangement comprising;
• at least one first magnetic field sensor for measuring the flux density at a first measuring position;
• and
• a second magnetic field sensor for measuring the flux density at a second measuring position at a distance from the first measuring position;
• wherein the measuring positions are positioned such that the rolling elements pass the measuring positions in contact with one another and a change in the measuring magnetic field caused thereby is detectable at one of the measuring positions by the respective magnetic field sensor;
• an evaluation unit connected to the magnetic field sensor arrangement for recording and evaluating the flux densities measured by the magnetic field sensors, the evaluation unit being configured, on the basis of a comparison of the flux densities measured by the magnetic field sensors, to determine diameters and/or changes in the diameters of the rolling elements;
• and
• the evaluation unit further being configured for recording and evaluating periodic time paths of the flux densities measured by the magnetic field sensors;
• wherein the comparison of the flux densities measured by the magnetic field sensors comprises determining a phase difference between the periodic time paths of the flux densities measured by the magnetic field sensors.