DE1648739A1 - Method and device for the automatic control of bars by means of ultrasound - Google Patents

Description

Patent attorney

0 ^ .Phy _S .Dr.Wa! Thsr3unaus

5 Hanover, Abbettr, 20

October 13, 1967

Dr.j / Ha.

My "file: 1365

Statni v £ zkumn; $ r üstav pro stavbu stroju, Bechoviee

Method and device for the automatic control of bars by means of ultrasound.

The subject of this invention is a "method as well as a Device for the automatic control of bars by means of ultrasound. -; ■ '"* - ..

Internal material defects in bars and rods are nowadays already determined fully automatically by means of ultrasound, with the test item between stationary and rotating Transducers passes through. Usually we work according to the impulse test method, with the transmission hall head periodically emits UltrasGhall impulses, "those from the surface of the test object and any material defects are reflected and return to the receiving transducer. Receiving and 5-end transducers can either be connected to each other be connected or spatially separated.

109824/0238

In the case of rotationally symmetrical test objects, these move along their axis; in some cases they also perform an additional rotation around the axis, whereby the test point describes a spiral movement on the test object surface. Rotation cannot be used for angular profiles. With the spiral movement mentioned, only low test speeds can be achieved. "If the test specimen only performs a longitudinal movement in the direction of its axis and if the transducers are stationary, the control is generally inadequate because the ultrasonic waves run in one, at most two, mutually perpendicular planes Increase, the number of test levels can be increased ". This increases the demands on the available test room, without there being any guarantee that the material defects will be displayed exactly. On the one hand, each transducer works independently, on the other hand, some material cases can be displayed several times in the event that they enforce several test levels. I ^{1 For} a high-quality automatic control, however, it is desirable not only to determine a flaw in the test item under all circumstances, but also to determine its character and identify it at the same time, i.e. to determine whether it is a spatial flaw, i.e. a cavity or a foreign body inclusion or a defect in the form of a simple or branched crack »

109824/0238 ~ - 3 ~

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The invention now allows on the one hand the uncertainty in Finding imperfections in the axial direction that are unfavorably oriented with regard to those used today, two or more reverb heads producing ultrasonic pulses at the same time send and receive, to eliminate and on the other hand at the same time the character of the defect in the described Sense to determine "

The essence of the invention is that an automatic Ultrasonic test method is used in which the test object is in the direction of its axis between transducers moved, which are arranged so that the ultrasonic beams at successive intervals along the entire Circumference or at least along half the circumference of the test object are sent out. This makes a similar one Effect achieved as if the transducers were rotating, because the ultrasonic test planes rotate perpendicular to the Movement of the test object.

The advantage of this method lies in the simplicity of the mechanical arrangement and the possibility of a higher one Test speed, because the electrical switching of the Ultrasonic beam from one probe to the other can be done faster than a mechanical rotary or Pendulum action, because a stop frequency of up to a few hundred Heart can be used.

1098 2 4/0238, ₄

The essence of the invention is explained in more detail using the exemplary embodiments shown in the drawing. Show it:

Fig. 1 the arrangement of transducers in a rod with a circular cross-section »

Fig * 2 shows the arrangement of transducers in a rod with angular cross-section.

3 shows the time dependency between the individual Impulses *

4 shows the basic circuit of the test device in a block diagram.

Both? As a test of rod material, a certain number of ultrasonic transducers - for example five transducers - (see Figs. 1 and 2) are arranged on the surface. The axes of two neighboring ultrasound bundles can, for example, enclose an angle of 45 °, which means that the ultrasound bundles of ultrasound heads 1 and 5 lie in one axis 45 ^O between the axes of the ultrasound trahlenbüadel provides with respect to a reliable indicator longitudinally oriented material defects any position an optimum. of course, a greater number of Sehallköpfen, arranged on the periphery of the test piece

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SAD ORIGINAL

are, permissible or even necessary, especially if Areas outside the axis are to be covered by the control. Usually the transducers are in arranged in a plane perpendicular to the axis of the test object. ' However, the jail can also occur that an arrangement the transducers in two or more in a row, lying test levels is more advantageous ^. As already mentioned the 5tttrasehall ray beam constantly changes its Direction, either in a belt along the size of the test object or in a pendulum motion.

The essence of the invention can be grasped very clearly by means of FIGS. 3 and 4. The essence of the invention is based on the successive activity of the hall heads arranged along the circumference of the test object. The ultrasonic reverberation impulses are emitted in m ieriqclQJa, which form a working cycle (see 3? Ig »3 and 4, m = 4). The number of periods m can either correspond to the number of Sohallkö | ife "or the number of transducers can be a fraction larger than the number of periods _v thus have the value m + 1 " This latter mode of operation is more advantageous and SQgar iü, dem if necessary where the transducers are not arranged along the entire circumference, as indicated in #ig, T and j 2. The number of m periods during which all transducers are in action

109824/0238 «6 -

m = 4), forms a work cycle that is then repeated continuously. Each transducer acts once during a duty cycle. Therefore, the frequency of the cycles corresponds to the transmission pulse frequency of the transducers. The number m means the number of transmission reverb heads and the number of periods in a working cycle. The probe pulses for the m transmitters are generated by an m-phase synchronizer 10. One of the ultrasonic transmitters 6 to 9 is connected to each phase of this synchronizer, and one of the transducers 1 to 4 is connected to each of the transmitters. from Pig. 3 shows, the ultrasonic pulse is always emitted into the test object at the beginning of a period. The emitted impulses are indicated by a comma, that is, expressed by the symbols t £, t «, t4" ßzid t £. The first period begins at time t- ^ and ends at time tp, which also signifies the beginning of the second period, and so on The duration of each period is chosen in such a way that all the pulse echoes in the test item can fade away, the lie1 of which must be below the display threshold transducers "the same Yorgang takes place during the other periods, while those who emit in a sequential manner, the other Sohallköpfe pulses and receive JTaeh m periods is a;. completed work cycle and the Ultraschallstrahlen- \ fully led consecutive in a test plane

109824/02 Si

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Jumps .from the first to the m-th transducer. For example 3, - where m = 4, the work cycle I ends at the time ΐ -, _, where likewise the fourth period ends and the first period of the following duty cycle begins.

According to the invention, those false echoes are decisive, which return to the transmitting transducer, in the given case thus the echoes tj to tjj, as well as the echoes that occur during the same period reach the neighboring transducers, i.e. echoes that are identified by the index £. Of the Sehall head that sends out a pulse during a period -and receives an echo, is known as an active transducer, and adjacent. transducers that operate during this . Period only echoes will be received and processed referred to as passive vision heads. In the ή — open period the n-th sound head is always active and the (n + lj-th sound head passive. If with yes periods hm-! Transducers use find, the first Sehallkopf is only active and the last only passive. Bas ratio of the echo heights at the active and the passive transducer allows a conclusion about the orientation of the reflecting surface with regard to the Axis of the emitted ultrasonic beam to *

If one is mediated by the proportions of the heights Summarizes information during a work cycle, can about the. Character of the missing parts in the test item a statement can be made "i.e. it can be decided whether '"

109824/023 *

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it is a spatial material defect, so around a bubble, or a foreign body inclusion. or around an extensive material defect, i.e. a crack.

For internal material defects with a circular cross-section the active and passive transducers produce echoes of approximately the same intensity with a maximum difference up to 6 dB if the ultrasonic beam is at an angle include a maximum of 45 °. The hallmark of such an error is m echoes from the active transducers and also m echoes from the passive Beliallköpf en during a work cycle. In contrast, for a simple one or branched fissure (for example, a fissure of cruciform Arrangement) in the Aehsenzone of the test object, the ultrasonic waves have a strong sense of direction and fall in the majority either, depending on the orientation into the active or passive transducer. When arranging several transducers, at least along half of them the scope of the test object (for example m = 4) already occurs it is no longer the case that a crack of sufficient size is not displayed, or that it is in the same area how a spatial defect is displayed. Cracks are identified by fewer echoes than m on the active ones or passive transducers labeled «An echo is considered a display error if it is more than 15 to 20 dB smaller than the largest echo, in Fig. 3 the time sequence of sending and receiving for the case m s = 4 can be followed well. At the beginning of each of the four one

109824/0238

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Periods t ^ + t ₂ , t ₂ + tj, t ^ -t- t ^ and t . + T- representing the working cycle, an ultrasonic pulse is generated by the active son at times t £, t ₂ , t 'and tC sent out. In general, this fact can be expressed in such a way that at the beginning of the η-th period a pulse is emitted by the η-th transducer. The echoes from the active ones are then displayed. Transducers, so the echoes, .that return to the place of emission, ie to the; η-th transducer, as well as the echoes of the neighboring transducer, i.e. the (n + l) -th; n transducer, which is passive in the deip-th period. It seems natural that the echoes also reach all other transducers, but there they are unimportant or even disturbing and must be suppressed. According to the invention, two groups of (EorscLialtungen 19> 20 (see 3? Ig »4) are used for this purpose, which only allow the desired echoes to reach the two amplifiers 27 and 32 η-th 'sound head via the circuit 19 to the first amplifier 27, which amplifies the echoes of the active sound heads and the echoes of the (n + 1) -th sound head via the switching unit 20 to the amplifier 32, the amplification • lsi riches serves said passive transducers the selection 'is the i'orüchaltungen 11 to 18 (for example, ^l / ^Dx'Vor3t::; .rkerBtufen). causes, by suitable SchaltimyLtLöVfirlaufe on the outputs 21 and 24 of Synohronisa-Lara 10 (see Pig. -Ja - 3d) ^ e can be touched * In.Pig. 4 can • nan oi-Lennen, that for example the direction T1 by the

108824/0231 '

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Signal Yes during period 1, during which Sehallkopf 1 is also active, is opened. In addition, the preamplifier 12 is also cleared during this period, via which the echoes from the passive transducer 2 reach the amplifier 32.

As already mentioned by Yfurde, the gate amplifiers 11 to 18 are subdivided into the two switching groups 19 and 20, each of which contains m bridged circuits which are coupled via the common outputs 25 and 26. The keying, ie the opening of the door postures, is effected by the rectangular pulses shown in FIGS. 3a to 3d. The first group 19 is supposed to output the echoes from the active transducers and the second group 2Q is to output the echoes. switch through the passive transducers. Only in the η-th period does that of the gate circuits 11, 13, 15, 17, to whose input the h-th transducer is connected, open in the switching group 19. and in the second switching group 20 that of the I / O circuits 12, H, 16, 18, to whose input the (n + 1) th sound head is connected. The outputs 25 and 26 of the circuit units 19 and 20 are routed to the inputs of the multi-stage upper, lower door 27 and 32. The amplifier 27 processes the signals from the active sound heads and the fully separate amplifier 32 processes the signals from the passive ones. Sound heads, üchou the relationships between the echo heights at the outputs of these two amplifiers allow a statement to be made about the character of the flaw in the test item.

109824/0231

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With automatic operation it is not possible to evaluate the echoes visually. According to the invention, the character of the material defect is assessed according to the number of echoes of a certain intensity that are recorded during a working cycle, i.e. after m periods, based on the outputs of the two amplifiers Output of the amplifier 27 during each working cycle m echoes of approximately the same intensity. In general, the difference in echo heights is no greater than 6 dB. The same can be expected at the output of amplifier 32 for the signals from the passive transducers. These echoes are generally weaker than the echoes from the active transducers, the difference; but usually does not exceed an ifert of 6 dB. From this G-round one can say that the typical characteristic of a space-symmetric üäterialfehlstelle m echoes at the output of the. both amplifiers 27 and 32 are. In contrast, in the case of two-dimensional material defects in the JPorm of simple or branched hiss, the number of echoes at one or the other output, sometimes also at both outputs, at the outputs of amplifiers 27 and 32 is less than m. According to the invention, the error identification is automated and that by evaluation circuits consisting of the storage circuits 29 and 34, so much voltage at their outputs. ^% stages occur, such as Echoa during a duty cycle to «

1098247023

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record -are. At the end of each work cycle, the display of the storage circuits _; . deleted «The corresponding extinguishing pulse is derived from one of the ultrasonic transmitters *. As an example, the voltage curves at the output of the circuit 29 for the posts eehos at the output of the amplifier 27 according to FIG. 3e are given. It can be seen that during all four periods the digit echoes t £, t |, tS and t £ emerge. At the output of the circuit 29 a voltage curve according to FIG. and the pulse t | _ expresses the absence of a flaw echo only during periods 3 and 4, see Fig. 3f. 3h * The two memory circuits 29 and 34 are usually connected via the selection circuits 28 and 33 ⁶ ^ ■ A ± s amplifiers 27 and 32 Circuits similar to those used in the monitors are used to display material errors in the circuits. 29 and 34. follow two more, of which the one from the HÖLitiiiialpegeiblimeril 30 and 35 * as well as the denz circuit 37. ^to display space-symmetrical material defects and the second, consisting of the maximum level limiters 31 and 36 as well as the circuit 38, is used to display voü I Eissen, "j

The automatic display of spatial defects, i.e. the "

109824/0238 _ ■ '.

The display of bubbles or foreign body inclusions takes place as follows:! Erectile signals pass through the minimum level limiters 30 and 35, which suppress m-1 voltage jumps and only pass on the m-th voltage jump in the form of a corner pulse (see Fig. 3i). If square-wave pulses from the two storage circuits 29 and 34 and the subsequent minimum level limiters 30 and 35 arrive at the "two inputs of the coincidence arrangement, a space-symmetrical material error is displayed. This only occurs if the outputs of the circuits 30 and 35 at the same time In the case of stress gradients marked in FIG. 3i, if the coincidence circle 37 indicates a spatially symmetrical liettejial error, such as a bubble, the crack indicator 38 is blocked.

In all other cases, if an echo occurs at the active or passive sounder heads at least in one period of a work cycle, the crack indicator comes into operation. Then incline at the output of the circuits 29 and. As many jumps in tension as can be found in the Mg. 3h Schoe. The Pig 2E symbolizes the Spahnungsverlauf at the output of the circuit 34, which corresponds to the voltage θ curve according to Pig, 3f at the amplifier of the passive transducers. 33er läaxitasl level limiter 31 in this case allows the rectangular apule shown in #MjE> - 3i through, u, et a voltage value corresponding to the maximum HÖU of the first stage

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entspricht.'In 'er et selb operates = Maxim Alp Yellow Grenzer 36 iet connected to the signal channel of the active transducers and forwards in en & I ¹ Ig, profile illustrated 3k en manner. Whenever a square pulse occurs at one of the outputs of the maximum level limiter 31 or 36 or at both of them at the same time, the crack indicator 38 is activated, which is not locked in this pail by a pulse from the incidence arrangement 37.

The advantage of the described method and the device for an automatic control of rods and rods by means of ultrasound lies not only in the possibility of a defect characterization either visually by comparing the echo heights on the active and passive transducers, or by an automated "detection", but rather also in the fact that both the coincidence ^{device 37 a1 * 3} and the crack indicator 38 emit electrical signals which can control a writing device, an evaluation device or an optical or acoustic signal system, even with the use of five transducers, m = 4, such as In 1 and 2, it is no longer the case that a crack of any orientation is not displayed because the impurity echoes are received in two different directions in each period or only moderately inclined cracks at least one of the five veins more sound heads one

Claims (1)

1ΒΛ8739- P at e η ta η s ρ r ü c h e:. ·,. i. Procedure for the automatic control of the tone of the device Ultrasound with axially advancing the rods with regard to a group of transmit and receive transducers in a direction to the axis of the rods • - vertically oriented plane arranged bind, characterized, , that the nth transducer from a group of 6 m transmitting transducers an ultrasound pulse at the beginning of each η-th period from a total of m periods, the together form a work cycle * in the test item sends out ■ and that the echoes received by the n-th transducer in the η-th second period pass through a gate circuit which is open in this η-th period and which belongs to a gate group (19). The gate circuits controlled from m with a common output (25) during which the echoes received by the (n + 1) * th Sehallkopf, which is located next to the nth Sehallkopf, pass through a further foro posture, which is also open in the η-th period and to a ZY ^ eite vector group (20 ) is one which consists of m controlled gates to a common output (26), it is critical for the type of missing adjusting \ in the test piece, occur much Fehlstelleneohos during an operating cycle at the outputs (25) and the two groups controlled gates 109824/0238 _<: - ie -; ■■■ "" ■■. ■■ in the sense that in the case of a space-symmetrical defect of the type of a bubble at each of the two outputs during a working cycle consisting of m periods, the same number of echoes occurs as there are transmitting transducers, i.e. m echoes during this time in the case of an ice lake, at least at one exit _; echoes appear, the number of which, however, is less than m. 2, set up for the automatic control of bars by means of ultrasound according to claim 1, characterized in that that it contains an n-phase synchronizing generator (10) ^ where one of the η transmitters with the η-th transducer is connected to each phase, the one with the gate circuits, those in two groups (19 »20). are divided, ver, is tied and each group m stances with common Contains outputs (25) and (26), the first Sehallkopf (1) only with the first gate circuit (11) of the Group ^ (19) is connected, while the nth transducer is connected of all transducers (2 to m) with the η-th gate circuit the Sruppe (19) is connected and at the same time with the (n-l) -th gate circuit of group (20) and the. (m + l) -th The transducer is connected to the outer m-th gate circuit of group (20) and the n-th gate circuit of group (19) "and the group (20) with the output of the n-th phase of the ^. Synchronisiergeiierators (10) is connected, meanwhile the 109824/02 38 _ _1? _ BATH common output (27) of the group (19) consisting of the '. Gate circuits (11 IdIs 17) exist at the amplifier (27) is connected and the Alis gang (26) of the G-rttppe (20), which contains the lor circuit en (12 to 18) into one identical amplifier (32) leads, 3 »Device for the automatic control of bars by means of Ultrasound according to claim. 2, characterized. that to the outputs of the amplifier (27) and (32) the 'selector circuits (28) and (38) memory circuits (29) and (34) are connected, the outputs of which via the minimum level limiter (30) and (35), which only the m-th .voltage stage, which during a work cycle arises, to the following coincidence arrangement (37) are connected, which contains a switching element. 4. Device for the automatic control of bars by means of ultrasound according to claim % characterized in that that at the outputs of the memory circuits (29) and (34) Maximum level limiter (31) and (36) connected are the first stage during a work cycle forward and these maximum level limiters (311 and (36) with an indicator for material cracks (38) «are * which contains a switching element. 109824/0238 -: ■ .- ■ - ■■. ·. ■ ■. . - te - BATH 5 · Device for the automatic control of bars by means of ultrasound according to claims 2 and 4 *, characterized in that that along half of the circumference at intervals of 45 ° five normal or W: U ± eisc ~ ä— «küpfe (1,2,3,4,5) are arranged, with the axes of the emitted ultrasonic beams die'Mitte of the test object push through.