For the oxygen enrichment of air two containers (11,11') working according to a pressure change process are provided. Each container (11, 11') is partly filled with a packed zeolite bed (13, 13'). Compressed air is fed to one container via a common closure device (41). At a certain pressure value a chamber (27) disposed in the container. (11) opens, with oxygen-enriched air flowing into the chamber. The oxygen-enriched air leaves the container (11) via an ascending pipe (37) and can be used as combustion air in internal combustion engines or the like. The one container (11) adsorbs the nitrogen from the compressed air through its packed zeolite bed (13), while the other container (11'), the chamber of which is closed, is desorbed. An oscillation generator (25) can be used to cause the packed zeolite beds (13, 13') to oscillate at high frequency and in this way to increase the adsorbing capacity and to accelerate the desorption process.

In a device for grinding workpieces, in particular workpieces made of ceramic materials, by means of a grinding wheel (24) or the like, the workpiece (23) is oscillated transversely to the machining direction during grinding. At least one ultrasonic transducer (1), whose ultrasonic energy is used as exciting energy for the workpiece (23), is provided as a device (20) for generating the oscillating movement of the workpiece (23). An ultrasonic resonance space (2,4) for amplitude transformation is provided between the ultrasonic transducer (1) and a sonotrode (5) which transmits the vibration to the workpiece (23).