Ultrasonic cutting device

A device for cutting by ultrasound, the device comprising at least one cutting unit including an ultrasound generator having a given natural frequency, coupled to at least one cutting tool, in which cutting unit the cutting tool is a disk driven in rotation, and the ultrasound generator is coupled to a central region of the disk via a coupling means, said central region being disposed on an amplitude antinode of the ultrasound vibration produced by the ultrasound generator in a given mode, or in the vicinity of said antinode, wherein the coupling means includes a bar of length .lambda./2 equal to half the wavelength .lambda. corresponding to the natural frequency F of the ultrasound generator, and having an upstream end coupled to the ultrasound generator and a downstream end coupled to the disk, the bar being of non-constant section that decreases from the upstream end towards the downstream end, and wherein the coupling means also includes a coupling element of length .lambda./2 which has an upstream end coupled to the central region of said cutting disk and a free downstream end so as to ensure that waves are returned.