Abstract: The invention relates to a method for a unique control of the frequency and utput power of a digital generator, in particular for an ultrasonic welding process. Based on a digital processing, the method according to the present invention compensates not only for variations of the resonant frequency in a broad range, but further provides to control a shifting of the resonant point during the welding process in response to temperature or pressure variations. Power variations caused by variations of the line supply voltage or by the pressure are detected and levelled out by the software. The software monitors the overall operation of in-line machinery, matches its parameters and monitors the complete cycle. The software further ensures an optimum efficiency and effectively protects the end stage against stress caused by high-reactive currents.

Abstract: An apparatus for testing hardness under load has a measuring sensor in the form of a manual apparatus in which a mobile rod-shaped resonator can be slidingly inserted. The free end of the resonator, situated outside the housing, has a measuring tip. The resonator is held against the housing of the measuring sensor by a spring and is linked to ultrasonic converters connected to an electronic generator and to a receiving circuit which records changes in the duration or frequency of the vibrations of the generator. A basic apparatus comprises a display unit and is connected by a connecting line to the measuring sensor. A memory for storing individual parameters of the rod-shaped resonator and the electronic generator is arranged in the housing of the measuring sensor. The basic apparatus is detachably connected by insertion to the measuring sensor.

Abstract: This invention discloses a method and apparatus for determining the hardness of a solid workpiece. An elongated rod is excited to be mechanically resonant along its longitudinal axis and is provided at its front end with a defined contact surface of hard material (Vickers diamond). When the rod is rendered resonant at its natural frequency of vibration .omega.o, the contact surface of the rod is pressed into the surface of the workpiece, whose hardness is to be determined, under a predetermined engagement force while the rod is forcibly maintained oscillating at the frequency .omega.o. A sensor coupled to the rod provides a signal indicative of the amplitude of vibrations of the rod when in forced contact with the workpiece and such signal is fed to a computing device for providing a value indicative of the hardness of the workpiece.

Abstract: The invention concerns an ultrasonic test probe for use in connection with testing workpieces wherein the angle of propagation of the ultrasonic search beam is adjustable. The probe comprises a linear array of ultrasonic transducer elements and a plastic wedge. An acoustic lens disposed between the array and the wedge causes the individual ultrasonic beams to come to a focus at an acoustic energy exit aperture of the probe. The angle adjustment of the ultrasonic beams is accomplished by energizing in-phase a respective group of transducer elements forming the array.