DE1473349C - Ultrasound examination method - Google Patents

Description

3 4

Clock generator with a step switch synchronized tuned filter 26. The filter amplifier 24 resp.

is, the latter switch being synchronous with the filter 26 on their specific frequencies

the frequency of the wobbler is matched to certain filters, with their output signals through

is adjustable. a detector 28 can be mixed and demodulated

The method according to the 5 denoted above. The signal is then passed through an amplifier 30

U.S. Patent 2,921,465 can basically be reinforced and the vertical baffles one

do not perform on every workpiece because the oscilloscope 32 is fed.

The wobble stroke of the wobbler is naturally very small. The gain compensator 14 can according to FIG is. In this regard, there is a wobble of 10 kHz when switched according to US Pat. No. 3,033,029 a frequency of 5 MHz. This can be implemented with a gain control signal NEN but obviously not the measurement results are like an amplifier, so that the input with the method according to the invention is obtained, the voltage signal is amplified in a ratio the, whose frequency range according to a preferred which inten with the decrease in the signal voltage Example is between 2 and 10 MHz. follow the from the pulse through the sample material

The method according to the invention offers decreases in all of the 15 running paths.

The common advantage is that a comparatively large amount of data is available. An examination is carried out with the two for a precise evaluation of frequencies located in a workpiece, 10 and 2.25 MHz. All frequencies recorded by the transducer 18 by maintaining inhomogeneities in terms of dimensions and position are possible. amplified in the receiver 22 and the filter - the invention is supplied below with reference to the amplifier 24 and filter 26, respectively. With strong .nung explained in more detail which one embodiment attenuating steel there is practically no arrangement for carrying out the inventive output signal at 10 MHz from greater depths than according to the method in block diagram representation 25 mm in sample 20. way correspond to the inhomogeneity 20 a, which a clock generator 10 leads a pulse generator 12, 25 is close to the surface, run through a gain compensator 14 and a switching filter 26 and the detector 28, are fed through the ter 16 a clock pulse. The signal of the clock genes amplifier 30 amplifies and requires an indicator 10 serves as a carrier signal for the pulse generator signal 32 α for an inhomogeneity on the screen 12, which generates a needle pulse α of high voltage of the oscilloscope 32. The gain compensator. The leading edge of the pulse is very steep α, 30 sator 14 is adjusted so that no signal of for example 2 x 10 ~ ² microseconds. The 2.25 MHz trailing edge through the filter amplifier runs until one edge of the pulse falls exponentially and time can elapse "which can be adjusted to a depth of approximately with respect to its fall time. A pulse corresponds to 12.5 mm of the sample material. After This of this type comprises a broad frequency spectrum, signals can pass through period This pulse eliminates which are normally present and which is fed to an ultrasonic transducer 18, which covers higher frequency signals to below 4 ° an echo signal in the lower frequency range, searching sample 20, which internal defects or in which, due to the homogeneity adjusted to 2.25 MHz, should have 20 a, 20 b. The wall filter amplifier 24, the detector 28 and the verier 18 responds mechanically to the electrical pulse which is stronger 30, with a second defect responding and generating a mechanical ultrasonic wave, signal 32 & displayed on the oscilloscope 32, which is indicated by the sample 20 in a known manner - 45 turns.

runs through and of the inhomogeneities 20 α, 20 & The inventive idea can deviate from - as is known - is reflected. A broadband to the execution receiver illustrated in the drawing 22 reinforces the approximately example carried out by the converter 18 also with an arrangement recorded signals and lies in terms of its will, at which the transducer more than two Response range within the 50 filter or filter amplifier to be examined are subordinated. In Frequency range. The receiver 22 speaks in such a case that an echo oscilloscope is obtained at frequencies in the range from 1 to grams with several occurring in succession MHz so that all pulse pairs in this frequency range are correspondingly different The recorded frequencies evenly amplified depths within the sample, with each being depressed. The output of the broadband receiver 22 55 is related to an inhomogeneity present there on a filter amplifier 24, which can be determined very precisely on borrowed its dimensions 2.25 MHz is tuned, and on one on 10 MHz can.

1 sheet of drawings

Claims (3)

If the inhomogeneity sits “deeper” in the workpiece, according to patent claims: if the frequency component having the higher frequency experiences greater attenuation than the one 1. Ultrasound investigation procedure to er- lower frequency exhibiting frequency component, which averaging of existing in a workpiece, 5 has the consequence that the amplitude ratio of the ultrasonic waves reflecting inhomogeneity of the two frequency components is changed, for example by introducing a frequency spectrum as shown in Fig 6 at the bottom of the article is placed in a factory. However, this does not result in a clear piece of reception of the reflected ultrasound wave evaluation, because, for example, in the case of an Auslen after it has been run through twice, at least 10 evaluation oscillogram according to FIG. 6 at the bottom of the area of the workpiece ^ conversion of the article it is not clear whether the localized received ultrasonic waves in corresponding inhomogeneity uni a hole of 0.8 mm through electrical signals and evaluation of their knife at a distance α or a hole with increased frequency components, characterized by a diameter of 3 mm at a distance, that is at least two out of 15 b> a . An unambiguous evaluation by means of the amplitude comparison filtered out of the electrical reception signals according to the article cannot therefore achieve frequency components of the "lower frequency". having a frequency component only after a loading. The object of the invention is to create a correct time since the introduction of the ultrasound - in contrast, improved procedure, which one impulse is amplified, which thereby unambiguous evaluation of inhomogeneities in It is true that at this time the higher a workpiece in terms of position and dimension frequency having frequency component due to allows. This is achieved by the fact that the propagation of the ultrasonic waves in the plant - at least two from the electrical receiving piece is already heavily attenuated. Signals filtered out frequency components of the low- 2. The method according to claim 1, characterized in that the frequency component first has a higher frequency indicates that each frequency component is amplified with an amplifying sound impulse that can be changed after a certain time since the introduction of the ultra-different and which thereby affects & h is reinforced. it is true that at this time the higher one Frequency component due to the 30 propagation of the ultrasonic waves in the workpiece is already strongly attenuated.
In contrast to the state of the art, other The invention relates to an ultrasound sub-message according to the evaluation, ie only the Search method for the determination of one and the same frequency component approaching workpiece in an amplitude existing, ultrasonic waves reflected, while the occurrence of different tating inhomogeneities by introducing a reflected frequency component only to the Feststelein Ultrasound with a frequency spectrum of inimpulses present at different "depths" in a workpiece, reception of the reflective homogeneities in the ■ workpiece is used. Example most Ultrasonic waves after double passage would be wise in the example according to FIG. 6 below at least a portion of the workpiece, converting 40 of the above article into the after of the received ultrasonic waves obtained in corresponding methods according to the invention Signals and evaluation of those! veroszillögramm the amplitude of the higher frequency stronger frequency components. having frequency component disappear when According to the article entitled »Determination the inhomogeneity a greater distance from the of.the Geometry _of Hidden Detects by Ultrasonic 45 workpiece surface as inclined, other-Puise Analysis Testing «in the magazine * The side dignity showing the lower frequency Journal of the Acoustical Society of America ", frequency share only later, but with in Wesertf-Vol. 35, no. 3, March 1963, an ultrasonic borrowing of the same amplitude has already occurred. In this way, investigation method of the type mentioned is known _: is not only a more precise evaluation with regard to the evaluation of the frequency components by 50 dimensions of the inhomogeneity, but also an amplitude comparison (see in particular Fig. 6 with regard to their distance from the workpiece top of the article) he follows. But now the amplitude area is possible. of a certain frequency component that of one according to US Pat. No. 2921465 is also Ultrasonic waves did not reflect inhomogeneity. , a method known that ends on a versus the only a function of the dimensions of the subject '.' SS according to the method of different prin-inhomogeneity, but also a 'function of the zip is based, namely the formation of standing waves attenuation of the relevant frequency component Each hole representing anhomogeneity of, for example, 3 mm was an inhomogeneity of the workpiece upper diameter, the amplitude of the higher frequency area corresponds to a certain frequency component exhibiting resonance, which is greater than the frequency which is filtered after reception and from which the lower frequency For this purpose, time-proportional is, so this only applies to a certain successive discrete frequencies in the distance of the inhomogeneity from that work-workpiece irradiated a is radiated on this discrete frequency. If, on the other hand, the correct filter is switched on in the example. The irradiation F i g. 6 at the top of the article the spacing of the inhomoders discrete frequencies is made by a wobbgenicity of the workpiece surface greater or lesser, which is via a sawtooth generator or a