Abstract: The invention relates to an ultrasonic measuring unit for attaching to a measuring instrument. The measuring instrument is designed in such a way that the measuring instrument can be arranged on a movement axis of a machine. When the ultrasonic measuring unit is arranged on the measuring instrument, an ultrasonic measurement can be carried out by means of the ultrasonic measuring unit. The ultrasonic measuring unit comprises a tubular sleeve and an elastic carrier element. The tubular sleeve surrounds the elastic carrier element. The elastic carrier element consists of a material that conducts ultrasonic waves. At a first end of the tubular sleeve, the elastic carrier element protrudes beyond an outer edge of the tubular sleeve. The tubular sleeve and the elastic carrier element are intended to contact, in particular directly, the surface to be measured, during a probing process of the measuring instrument.

Abstract: A sensor carrier is provided that has at least one oscillating element (32) that introduces ultrasonic waves into an area to be examined and/or receives ultrasonic waves coming from the area to be examined, whereby the oscillating element (32) is located in an oscillator carrier (33), and the oscillator carrier (33) has connecting means (36, 37, 38, 39) for connection with the electrode (31).

Abstract: The invention relates to an ultrasonic sensor system, especially for controlling a resistance welding process. Said system comprises at least one receiver which is used to detect the ultrasonic signals from the area to be examined. At least two piezoelectric sensors (31, 32) are used as a receiver and are arranged in such a way that their polarization direction vectors indicate various directions, said vectors being projected in a plane perpendicular in relation to the propagation direction of an ultrasonic wave to be detected.