DE2245621A1 - AMPLITUDE-ADJUSTABLE PULSE TRANSMITTER FOR ULTRASOUND TESTING - Google Patents

Description

Hoesch Aktiengesellschaft, 46 Dortmund, Eberhardstrasse 12 Amplitude-adjustable pulse transmitter for ultrasonic testing

! The invention relates to a device for generating pulses for

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Excitation of ultrasonic transducers by means of pulse capacitors and semiconductors.

Such devices are used to measure runtime using ultrasound and perform amplitude assessments. Areas of application in non-destructive material testing include wall thickness measurements or the detection of material defects such as cracks, slag ingress

,

Inferences and doublings. -

An electrical impulse is generated by a transmitter that sends a . Pulse transducer, a so-called ultrasonic transducer, fed to and from this is converted into an ultrasonic pulse. The ultrasonic pulse is transferred to the test item via a coupling medium such as water or oil

Workpiece coupled in · When checking for possible material defects, such as

For example, when testing weld seams, the sound pulse passes through the workpiece. An existing error reflects part of the transmitted ultrasonic pulse, which returns to the pulse transducer as an echo. This ultrasonic echo at the pulse converter is converted into an electrical pulse, which is amplified by an amplifier and 40981 3 / 010S - ² -

ORIGINAL INSPECTED

is evaluated by an electronic evaluation device

For tests with a relative movement between the test object and the pulse j transducers occur unwanted fluctuations in the coupled into the workpiece Energy through changes in the sound conductivity of coupling medium and Material as well as differences in the surface. The same interfering influences also occur in the case of a return from an error to the pulse converter Echo noticeable. This means that the same faults in different places of the Material tests lead to different evaluations.

j this over istand is remedied by the ultrasonic test in such a way that ί that the echo pulses on the one hand and the quality of the coupling on the other

ί measures separately. The deviation of the coupling amplitude from the specified target

ί value is fed to a control amplifier on the receiver side as a manipulated variable,

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which corrects the deviation from the setpoint, so that the downstream Evaluation device the errors are evaluated equally.

With this method, fluctuations in the coupled energy are only corrected on the receiver side, although equally one Correction of the transmit power would be required. This means that the scope of the regime must of the amplifier on the receiver side may be unnecessarily large, if not one different assessment may remain in borderline cases.

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measurement, the regulation on the receiver side alone is not sufficient,

if at the same time the transfer amplitude between two pulse converters is conj should be kept constant or valued.

In such cases, in which the position of the receiver sensitivity alone is not sufficient, adjustable attenuators have been used up to now. These were also used to adjust the individual channels in multi-channel test systems. However, damping components have the disadvantage that they are, on the one hand, very expensive and, because of their inertia, not suitable for automatic control.

The invention is based on the task of both the individual adjustment of the Pulse converter in multi-channel test arrangements as well as the necessary setting of the transmission power in automatic test mode without use to enable attenuators.

During the individual adjustment of the correction of the electroacoustic efficiency the pulse converter is used, the position of the transmission power in the autoj matic test operation to adapt to the coupling and conductivity conditions that change during the test.

J The solution to the problem according to the invention is a device which allows the pulse amplitude to be specified by the charging amplitude of the pulse capacitor with a setting command at a predetermined, preferably linear, related.

409813/0105

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According to a further feature, the charging amplitude of the pulse capacitor is kept constant until the pulse is triggered.

A preferred embodiment of the invention is shown in the drawing shown schematically and is described in more detail below. It demonstrate:

Fig. 1 is a block diagram and 2 shows the diagram of the voltage curve

on the pulse capacitor if there is a difference "

borrowed loading amplitudes

According to FIG. I, the release pulse for

the operator 2 and the transmission trigger pulse for the thyristor 3 f »e-

I educate. As soon as the Frelgäbe pulse is pending for the comparator 2, j

the amplifier 4 via the transformer 5 the pulse capacitor 6 to j

charge the predetermined amplitude.

The pulse capacitor 6 is charged until its amplitude corresponds to the specified control value at 7.

4098 13/0105

The voltage on the pulse capacitor 6 is constant until the transmission trigger pulse "Ehalten" The transmission trigger pulse causes the thyristor 3 to Spontanentladunf of the pulse capacitor 6 via the not shown, to 8 connected pulse converters *

FIG. 2 shows the time profile of the charging voltage on the pulse capacitor 6 between the release pulse and the transmit trigger pulse for different setting amplitudes.

4098 13/0105

Claims (1)

Hoesch Aktiengesellschaft, 46 Dortmund, Eberhardstraf * «12 1. A device for generating pulses for exciting ultrasonic oscillators by means of pulse capacitors and semiconductors, characterized in that the charging amplitude of the pulse capacitor (6) is related to a setting command at (7) in a predetermined, preferably linear, relationship. j 2. Device according to claim 1, characterized in that the loading amplitude of the pulse capacitor (6) constant until the pulse is triggered is held ·. 4098 1 3/0 1 05