The state of the art discloses an ultrasound testing device consisting of a testing-head carrier having entry drill holes for coupling water and an exchangeable chamber attached thereto for containing (receiving) the coupling medium as well as a guiding mechanism connected to the device. In the center of the testing-head carrier, a testing head is provided so as to emit vertical sound waves in order to check wall thickness and lamination or double draw which can occur during the manufacture of a metal, particularly the rolling of steel. In addition, four testing heads are situated in a circle, each staggered 90 degrees, emitting slanted waves in order to detect defects. Two testing heads situated opposite one another form a pair in order to perform the same type of defect testing, i.e., one for longitudinal and one for transversal defect testing. The axes of the sound waves from the five testing heads focus on the surface of the test piece at a common testing spot. In order to form an aqueous path for the waves, an exchangeable chamber with a central water containing channel is positioned at the testing-head carrier. In order to eliminate the disturbing sound reflection generated at the walls of the channel, the channel wall is provided with a 90 degree corrugation showing a slope. In order to position the ultrasound testing device on top of the test piece, the device is connected with a guiding mechanism displaying protective bottom pads shaped in conformance with the contour of the test piece and being in contact with the test surface during testing. The disadvantage of the above described device is readily apparent in the unsatisfactory performance due to the low pulse sequence frequency and the device's inability to operate disturbance-free during the conducting of the water.
From German Patent Application OS 27 51 810, an ultrasound testing device for non-destructive testing of welding seams is known, whereby a total of six testing heads are placed in a testing spindle, and the sound waves intersect at one point. The sound-conveying coupling medium is achieved by feeding water to the contact plane. A drawback of this arrangement is that the coupling medium is fed in an uncontrolled manner to the testing device and that thereby the coupling control expense is very high. Moreover, due to cyclic prompting of the individual testing heads, the performance of the device is very low, since it is necessary to wait for the echo of the input pulse before the next pulse can be generated. A further significant disadvantage is the fact that the testing heads are mounted in individual holders that change their positions relative to each other when tolerances of the testing piece or tolerances in transport and guiding occur.