DE2044535A1 - Arrangement for non-destructive testing of steel parts - Google Patents

Description

Applicant: Dr. Friedrich Förster 741 Reutlingen Grathwohlstrasse 4

Arrangement for non-destructive testing of steel parts

The invention relates to an arrangement for non-destructive testing of steel parts using the magnetic leakage flux method.

There are arrangements for non-destructive testing of steel parts became known where the workpiece to be tested, e.g. billet, rod, pipe, etc., is flooded with a high current. While the current is flowing through it, the workpiece is immersed in an emulsion of magnetic powder and liquid, or in the Workpiece immersed in the emulsion is exposed to a current flowing through it for a certain period of time during immersion the workpiece is lifted out of the emulsion and, after the liquid has dripped off and the current is switched off, on magnetic powder accumulators, which point to errors, considered and these places marked with chalk, for example.

In another method, the workpiece is opened while the current is flowing through it dusted with magnetic powder. Then it will be exposed to a strong current of air under current, which removes the magnetic powder in the places where there are no lines of force of flow emerge from the workpiece, so that the remaining magnetic powder prevents the leakage of leakage flux, i.e. the Indicates the presence of errors.

These discontinuous testing processes are relatively cumbersome and tedious, because they do not fit easily into the material flow because of the long time required for the test permit"

209820/0114

y ** μ

hl]; ir.v ::: ^ ln, sc ::, L before some Ssit rait help of £ Or3 ": inrir'AStoqT ^ .riiieverfa":.:.; ene 'Induatrie-RuVidschcra, - -jahraan: · "ί ISS

0 uric Γ, S, -Pate-it. Ar -neldunc: BIT 641 53 "yen, 26.5,1967) aiico

;;; .. "- cij.esaiii"'is experienced by the passing stick with the help of ν ::. "., 3ohXe! fender brushes air. Current supplied, soft over the stick ·? - ·: a stared piece}: magnetized "in this · rognetisiarten Itiiippelstück the Magnetographiekopf is mounted at the. rolls an S";;"Hc-aes Macn & tbana Instead of eggs previously ermähnten l-laawzt pali'aransamnlung of errors learns this, the magnetic tape a local Aufnagnetisierang by the error diffusion flow, v / elk anschlisssend by a rotating magnetic head is scanned and visualized on eifie-n luminescent screen. at the same time Fehlerirapulse displayed by the magnetic head are used to elicit a site-■ faithful color marking of the error on the stick itself.

This supply of the MacmetisierungsstroiL-as has stenpaare grinding brushes. the disadvantage that the stick can not be checked until the last end. Furthermore, the coastline wear is to be regarded as a disadvantage . Burate wear and tear depends heavily on the surface properties of the billets .

If ε, B. The rolling mill of the billets is not properly eliminated in a de-idling plant, v / as, for example, with the extraordinary sundering of nickel-alloyed steels, one of the brush areas will burn through if the contact surface of the brushes is not large enough too high current load.

To avoid the costs of brush wear, arrangements have been proposed in which the high magnetizing current is supplied by steel rollers that are extremely tightly pressed against the billet (patent application P 1573510),

209820/0114

At the same time one tried the unchecked stick ends, which when contacting thirsts should be avoided inden the Sticks "abut-to-abut" run through the magnetization system with the supply of current through strongly pressed rollers.

The magnetizing current through the contact point of two successive sticks flow.

This arrangement of the butt-to-butt current magnetization also has some disadvantages: The point of contact between two consecutive sticks cannot be precisely defined. It can be a one-point contact occur with a few mm 'of contact surface. Apart from the resulting possibility of burning or hardening of the contact area is the change in level of the Hole circuit, as caused by such an undefined contact through the billet ends can be effected, a current constant maintenance required, the magnetizing current at a few thousand amperes as well as the very short readjustment required represents a considerable effort.

An even greater magnetization effort recently required Known billet test procedure (Oerlikon swiss notifications, May 1970, "dry powder testing equipment based on the magnetic Flooding for the objective determination and fixing of surface defects on semi-finished products. ") With this magnetic powder process should be in the material flow, i.e. worked in a continuous cycle will. For this purpose, the billets are passed through contact rollers, butting against one another, and magnetized. On the magnetization path, a ferromagnetic dry powder is brought onto the billet by an air stream. At The powder builds up flaws. Behind the spray box of the dry powder is used to fix the powder beads The surface of the billet was sprayed with a thin layer of white paint. In the area of the powder beads, the paint layer does not adhere, so that the defects in the billet are caused by darker displays on light Basically appear.

0 9 8 2 0/0114 'B. -.D ORIGINAL

2QU535

For this reason, the forehead contact is used in this billet test particularly elaborate because they are relatively complicated LaaeiIsnrüder must be used, which do not have longitudinal, but only a marking occurring transversely to the direction of the fault in the oversprayed white paint through the electrical contact be allowed to leave behind. Such face contact with inclined cutting edges can burn the billet surface appear,

The authors of the mentioned report write on page 6: "Any burn marks can only be perpendicular to the crack position, i.e. perpendicular occur to the axial direction and thus do not affect the drawing accuracy. "

This means that with this type of face contact using lamellar wheels with contact cutting burn marks on the billet surface may occur.

The high-current contacting of the billets or other test parts is, as shown above, a very general problem. if you want to work in a continuous material flow. The different types of contact (brushes, Only use steel rollers, lamellar wheels with cross-cutting edges, etc.) if the surface of the billet has been properly cleaned by Entzun ™ system has been cleaned.

Extensive experiments have shown that without Previously effective descaling of the billet, high-current contacting according to the previously described method is not possible.

Without a doubt, the procedures described above would be an extraordinary one Experience simplification if the magnetization of the billet or a slab or other test part is transverse carried out to the longitudinal axis without mechanical contact with the stick could be.

OTllClKAL

209820 / 01U

Quite apart from the simplification of the methods described above, magnetization of the test parts would be without mechanical Current contacting make this method accessible also for non-scaled material.

Indeed, there is an extraordinary need in the steel industry before, often only for non-destructive error testing to avoid necessary, relatively expensive descaling process .

To understand the invention described below, a few remarks on the distribution and penetration depth of a magnetic Field in a ferromagnetic material: ^

If, for example, a direct current is applied to a stick, which flows axially through the stick, then the density of the direct current is constant over the entire cross-section of the billet. In the case of a round billet with a circular cross-section, the direct current Generates a magnetic field in the stick, which is constant over the entire circumference. This constant peripheral field strength H is generated a constant magnetization B in the surface of the round billet, corresponding to the relationship of the magnetization curve between exciting field strength and excited magnetization.

If it is, however, a square billets, which is traversed by a * DC, so although the current density over the cross-sectional area of the billet is constant, however, the surface field strength at the flat stick surfaces is substantially different from the field strength at the stick curvatures. This effect is generated because lines of magnetization force emerge from the iron in the immediate vicinity and in the area of the edge curvature, which weaken the field strength generated by the current. For this reason, the field strength in the area of the curvature of the square billet is weaker than on the surface of the billet. This disruptive effect, which can theoretically be explained in a quantitative way,

20S820 / 01U

- ^; : -S ".-; it is irrelevant that the error reproduction at the stick edges with a non-destructive magnetic flux leakage method, depending on the radius of curvature of the radius of curvature, is more or less behind the error correction on the stick surface,

, 'rs.r, y this one; Basic card already suggested in the cited report (Gerlibon Scnweissmitteilungen May 1970) _for the magnetization of the billet in the magnetic particle test with alternating current as raw. respectively,

If a '/ ech be current flows, e.g. with a frequency of 50 JIz, a \ if ah! Is This follows the magnetic field surface, theoretically easy 2ii prove how better the curvature of the stick edges Darcb a Wechseistrcrmnagnetisierimg but against the etisierang not Veniger energy needed.

for aas magnetography process is. !. an AC magnetic - but .- ;; not ation after the prior art applicable because the dispenser, the magnetic tape on the stromchircht ".-; ended stick, in a fault leakage flux, ⁴ depending on the iiicri.srita-ia current value At the moment the magnetic tape is lifted off the jiüppel, any value between the highest positive and He ₁ Jd Liver display can be recorded.

St; - ciaeem reason were suggestions (patent application P 1573510} night; the gain of the magnetography amplifier To regulate the scanning process of the magnetographic tape in this way d ^ u-ii failed to reduce the edge error reproduction again equalized),

Proposals have already been made (patent application P i'al'JbiO and Nieder !. Pat.Anm, 6815174), instead of the Strora-H, ufUna ir : -ue ^ liaXbr / eilen-DC current to be used. Here f- · - ■ '. ·' :. ':. the magnetization required for the magnetography process in only

209820/0114

"■ /" ■■

in one direction, however, the magnetization field spreads due to the rapid change in the magnification intensity in the essentially in the vicinity of the billet surface, which also reduces the field strength in the vicinity of the billet edges is reduced, so that an improved reproduction of the edge defects results.

In all of the magnetization processes described above, however, one is always dependent on the electrical contacting of the billet.

If one tries now, a billet 1 perpendicular to the longitudinal axis through a magnetization yoke 2 with the excitation windings 3 and the Direct current sources 4 according to Fig. 1 to magnetinleren, so are to " very considerable field strengths are necessary, since the stick 1 represents a strong magnetic short circuit on the one hand, and on the other hand but due to the necessary gap 5 between stick 1 and yoke 2 an extraordinarily large internal demagnetization factor having. This large internal denagnetization factor arises from that from the free pole faces 6 of the stick 1 lines of force 7 proceed which are opposite to the field strength generated by the yoke 2 are directed. As a result, the field strength H generated by the yoke 2 and applied to the stick 1 is reduced. By the self-demagnetization process of the stick 1 by the free Stick pole 6 greatly reduced true field strength II is:

^H w ~ ^H a "" ^NI

Here I is the magnetization of the stick 1 and N that of the Geometry of the stick-yoke arrangement given internal demagnetization factor.

This reduces the so-called apparent magnetic permeability or shape permeability of the billet to low values.

As the parts to be tested for magnetic flux in general over the so-called knee of the magnetization curve, i.e. must be magnetized to an induction B of about 12,000 Gauss,

209820 / 01U

this means an extraordinarily high yoke magnetization field strength of a few thousand Oe.

Due to the interaction of the lines of force of the yoke and those emerging from the stick due to the high demagnetization factor Stray force lines, the area of the stick between the constant field yoke is completely contaminated with stray lines, so that once the stick has a very inhomogeneous magnetization field strength across its width receives, on the other hand, a magnetic powder still magnetography test is possible because the in this yoke arrangement Strong magnetic gradients that occur can exert considerable forces or magnetizations on the powder or magnetic tape would.

The invention has as its object a leakage flux test arrangement for checking the defects of steel parts, in which, while avoiding the disadvantages and difficulties described, a continuous magnetization of the parts to be tested is possible with relatively little effort.

According to the invention, this is achieved by the magnetization the steel parts provide ferromagnetic plates, depending on the steel part to be tested or the area of this steel part to be tested are arranged adjacently, the strength of which is small compared to the strength of the steel parts to be tested and that of a be magnetically excited by the winding through which alternating current flows.

In many cases, the technical alternating current of the supply network be used for the excitation of the field plates. However, it is very advantageous to adjust the frequency of the alternating current in this way choose that the Lindring depth of the magnetizing field in the billet is small compared to the thickness of the one with a winding provided ferromagnetic ^! Plate.

This means that the stick is no longer a magnetic short circuit, as the magnetizing field is only in one Layer thickness in the order of magnitude of e.g. 1 mm depth.

209820 / 01U

This gives the billet the behavior of a thin-walled pipe, which can be magnetized with very little energy.

Because of the relatively thin magnetization zone on the surface of the billet and because of the alternating field magnetization losses the surface of the billet between the two ferromagnetic, alternating-field magnetized plates is relatively high magnetic resistance.

However, this means that the magnetizing circuit may also have a high magnetic resistance, since the stick does not more like the constant field yoke represents an extremely strong magnetic short circuit.

“This high magnetic level allowed for the magnetization unit However, resistance offers a number of highly significant technological advantages:

1.) the magnetization unit no longer needs a closed yoke, which for a low magnetic Resistance is required to exist,

2.) The magnetization unit can be made of freely movable ferromagnetic, There are relatively thin plates excited by an alternating field, which can easily be attached to a passing stick have it put on,

3.) When using free magnetizing plates, it does not occur because of the high magnetic resistance of the entire circuit depends more on the width of the air gap between the magnetizing plates and the billet,

4.) The free movement of the plates enables it by simple mechanical arrangements that the easily movable magnetizing plates with rollers against the passing through Let the club lay,

5.) In contrast to contact magnetization, there is a thirst no more untested end, as the magnetization field strength is constant as it passes through the stick to the extreme end remain,

209820 / 01U

6.) errors of the same depth in the curvature, the shoulder and the center of the stick result in an equally strong error leakage flux,

7.) the generation of a certain magnetization field strength The energy required by the stick is only a fraction of the energy required for a current flowing through it,

8.) the complex contacting device is completely eliminated, 9.) The expensive regulated high-current system is also omitted, 10.) no mechanical or thermal traces (burning traces) from the contact devices can remain on the stick,

11.) The alternating field magnetization of billets by the magnetizing plates no longer affects the quality the descaling of the billet, so that now also not descaled Sticks of the magnetic leakage flux test become accessible in the run.

In some cases it can be useful to use the ferromagnetic To give plates for magnetizing the test pieces a magnetic return made of ferromagnetic material. This can e.g. done by placing a ferromagnetic core with a U-shaped profile on the plates. Furthermore, within the framework of the Invention conceivable as a borderline case that the plates interlock at the rear pass over and form a yoke-like unit.

The invention is to be explained in more detail below with a few examples on the basis of sketches. Show in detail Fig. 1 - as already described - the conventional yoke magnetization of a billet with direct current,

2 shows the magnetization of a billet according to the invention with ferromagnetic plates,

3 shows the test arrangement according to the invention for billets,

4 shows the test arrangement according to the invention for weld seams,

5 shows the test arrangement according to the invention for fin tubes .

209820 / 01U

The possibility of testing parts such as billets, slabs, etc. without mechanical Magnetizing contact in such a way that cracks result in a magnetic leakage flux opens up a considerable simplification Numerous magnetic crack testing methods for billets.

The magnetic particle test described at the beginning, in which the Stick dipped in an emulsion of liquid and magnetic powder and magnetized with a high current through the stick "can be extremely simplified with the help of the invention will.

Here, first of all, a magnetic powder crack detection system is to be used with reference to FIGS. 2 and 3 for billets and similar elongated steel | bodies are described, which are characterized by the invention The idea of contact-free magnetization of the billets can be implemented particularly easily and with a fraction of the effort, as the previously described procedure of the magnetic particle pre-test of Requires clubs.

For testing, the billet runs through a short chamber 21 in which the alternating field magnetization plates 11 magnetize the billet 1 with an alternating field as shown in FIG. By "selection of the length of the magnetization plates, the billet surface at a normal running speed can be magnetized in a sufficiently long period of time, then that with a spraying attachment * tung for magnetic powder with the nozzles 22, 23, and 24 sprayed on the billet surface of dry powder to the FehlerstreufJuss in Can be deposited in the form of a bead, while it is blown away at fault-free locations by an air stream, not shown.

Directly behind and in front of the chamber 21 are an or above the stick several ultraviolet lamps 25 attached, in the light of which fluorescent magnetic powder beads light up brightly at the location of the defect.

These error marks, which are generally much brighter with dry powder than with wet powder, are set by the operator hand-marked with paint, chalk, etc.

209820 / 01U

20U535

The operator remains in his place or sit, while the stick 1, the chamber 21, which is the contactless magnetization and the powder spray and blower contains, happens. After the billet has passed through completely, it is rotated axially through 90 ° on the transport device 28 and passes chamber 21 in the opposite direction by reversing the transport drive. The operator 27 has positioned himself on the opposite side of chamber 21, to view the second side of the billet as it exits the chamber 21 and to mark any glowing defect beads.

fe By reversing it three times, all four sides of the appear Knüppels in front of the examiner for marking, the examiner essentially could stay in place for examination.

The 90 ° rotation and reversing the direction of travel of the stick can can be easily automated. The Ρχ-üfer, which the test process can carry out while sitting, holds in his hand or has an operating unit directly in front of him, with which he can press a button can stop the stick for closer inspection or repeat the test on one side.

The seat of the examiner can easily be arranged with castors so that the examiner can check the stick sides moving back and forth on both sides of the chamber 21 W without having to stand up.

Due to the intensity of the fluorescent light powder, the ultraviolet illuminated billet can be passed through rotating photocells can be scanned, whereby the glowing defect bead is converted into an electronic signal. By the width of the stick is divided into several channels, that can be achieved by a chain of paint spray guns, which these channels are assigned, the defect beads are automatically marked with color at the location of the defect.

209820 / 01U

In order to avoid the back and forth movement and the respective 90 ° rotation of the billets , the arrangement according to the invention can be made so that the billet passes through two magnetization and spray chambers one behind the other. In the first chamber, the two opposite sides of the billet are magnetized by the magnetizing plate arrangement and sprayed with powder, which is then scanned by photocells, as described above, whereby a localized error marking is triggered by a row of paint spray guns, which are over the two tested Stick sides are attached. When passing the following magnetization and spray box, the process is repeated for the other two sides of the stick.

Instead of converting the light from the fluorescent powder beads The fluorescent powder beads themselves can generate electrical impulses, which in turn trigger a true-to-place color marking by spraying an extremely quick-drying, colorless coating immediately after its formation in the magnetic Alternating field can be fixed.

If the use of fluorescent powder is to be dispensed with, another method can be used. Here the billet passes through the alternating field magnetization plates while the two free billet sides are sprayed with magnetic powder. Immediately afterwards, they are on these two sides of the stick Defect beads formed by spraying with a thin dye I layer fixed. Immediately afterwards, the billet passes the second pair of magnetizing plates, which are perpendicular to it the first pair to create the magnetic powder beads on the two remaining billet sides and then to fix them.

The magnetic powder used is as black as possible in color, which is color-repellent. After spray over of magnetic powder caterpillars by a light color, the places where powder caterpillars were located appear as dark lines.

209820 / 01U

AIG further possibility of the magnetic particle testing of billets unc ^1-like bodies in connection with the contact-free passage of the stick through the Wechselmagnetisierungsvorrich'tung is proposed according to the invention, that the magnetic powder contains substances which interact with the fixing liquid in physical or chemical reaction. For example, such a reaction can result in a noticeable discoloration of the fixative or of the magnetic powder bead itself.

This discoloration can still increase according to the amount of collected Spread out the magnetic powder (i.e. roughly corresponding to the size of the defect) to the side of the defect bead so that the Visualization of the flaws in the billet through such a reaction between the powder bead and the fixative is considerably improved can be.

But not only the crack test using the magnetic powder method, but also the magnetography method discussed above ("Industrie-Rundschau," Volume 6, 1951, page 58 and U.S. Patent Application SN 641 659 dated May 26, 1967) of the billet test learns from the alternating field magnetization process with non-contact magnetization plates a decisive further development and simplification. The magnetography method in which the error stray fluxes are stored in a magnetic tape, which is then scanned line by line by a tape head, is the principle her Considerably superior to magnetic powder processes: On the one hand, from the level of the error signal obtained by scanning the magnetic tape in a certain scatter can be deduced from the depth of the defect. Furthermore, the error signals of the magnetography method Use for statistical quality control by adding the total defect length of each or the total number of tested Billet is printed out which information is of extraordinary interest for a rolling mill.

Then such error depths can be signaled for dimensional reasons can no longer be removed from the stick.

209820/0114

- is -. 20U535

With regard to future developments, which are clearly based on the fully automatic removal of defects from the billet the magnetography process enables z; 2t. as only test method obtained electronically from the magnetic tape Error impulses for an automatic control of the error removal (patent application P 1946 510) by grinding, scarfing etc. to use.

In the preceding description of the magnetization of billets, it was pointed out that AC magnetization cannot be used in the magnetography method according to the prior art. Of the magnetic tape depending on the instantaneous current value at the moment of lifting - - thus also the value 0, any value between maximum positive and maximum negative display, held in place by the magnetic tape during rolling of the previously-magnetized magnetic tape on the flooded Viechseistrom stick * may in one error diffusion flow will.

For the magnetography method according to the prior art, the lateral stick magnetization can therefore be carried out Do not use magnetizing plates excited by alternating current.

According to the invention, however, the magnetography method is entirely specially adapted to the alternating field magnetization by the previously described lateral magnetization plates by the magnetography tape used before overflowing over the stick f is not demagnetized to the neutral zero point, but magnetically saturated.

For example, the magnetically saturated in the transverse direction to the stick axis With an alternating field magnetization of the billet, tape can only have such a magnetization direction of the leakage flux cause a change in the tape magnetization, which acts opposite to the saturation direction of the tape. From the positive and negative half-wave of the sine field can only apply an error signal to the magnetic tape which is opposite to the direction of saturation applied to the tape.

209820 / 01U

The saturated magnetic tape has a kind of "rectifier effect," by an error leakage flux caused by an alternating magnetization from the opposing magnetization devices is caused, only one comes into effect.

This "rectifier effect" occurs in all three directions of saturation: "lengthways," "across" and "perpendicular" to the magnetic tape.

By using the alternating field magnetization of the billet by lateral magnetization plates, the magnetography method is also used With saturated dand the following significant progress was made: This was achieved through the side magnetization plates fe alternating magnetic field generated on the stick occurs in the middle of a Stick surface and occurs on the middle of the opposite " Stick surface off again. However, this results in a different structure of the magnetic field perpendicular to the stick axis compared to the field generation by current flow. The constancy of the field over the surface and edges of the billet is non-contact The magnetization process is already significantly better than with the current · ^ flooding the stick with alternating current and naturally much better than with a current flooding with direct current.

This in turn has the consequence that an error of a certain depth, e.g. in the middle of the surface, the middle of the edge or on the shoulder on the side of the edge, practically independent of the defect location ™ the stick an error signal of the same level in the magnetography process gives away.

With this new version of the magnetography process with lateral alternating field magnetization by alternating field magnetizing plates using magnetic tape saturated in a certain way, the "electronic gain increase for the _{billet edges f} " which was absolutely necessary when the billet was flooded with direct current in order to compensate for the considerable drop in field strength of the direct field at the billet edges is completely eliminated .

209820 / 01U

- II-,

As can be seen from the theory, this DC field applies to the edges of the billet with direct current flow. so much the greater the smaller the edge radius is. While with an edge radius of 15 mm the magnetography signal of a certain error in the edge is reproduced about four times smaller than the signal of an equally deep error in the middle of the stick, that is The ratio of the signals of edge cracks and surface cracks with an edge radius of 5 mm is already 1:15 to 1:20.

In contrast, the further development of the magnetography method described here with alternating field magnetization by means of lateral plates and saturated magnetic tape results in a signal ratio of edge and surface cracks with an edge radius of 5 mm of i exactly 1: 1. This means that the field strength distribution with this new type of magnetization by alternating field plates on non-circular cylindrical bodies such as square billets or other profile material is more homogeneous than was previously possible with a current flow magnetization process.

However, this results in a number of applications in which the previously used magnetic powder flags are now very easy to use handling magnetography procedures can be replaced.

An important problem is the inspection of weld seams Ships, containers, bridge structures, profile girders, in particular also on vertical and overhead surfaces. " The magnetic powder process is extremely laborious to use here, as the magnetization occurs once through pressed copper contacts is reached over only a short distance and on the other hand the flushing with magnetic powder emulsion during magnetization on walls in a vertical or overhead position to considerable difficulties pushes.

According to the invention, the magnotography method with ⁴ .t alternating field plates and saturated magnetic tape results in a number of new test possibilities.

209820/0114

For this purpose, according to FIG. 4, a magnetography supply belt 31 in one manually guided container 32 by a foam rubber roller 33 on the surface to be tested or weld seam 34 etc. pressed. When moving e.g. the weld seam 34 through the handle 39 guided magnetic tape container 32, the magnetic tape 31 is rewound from the supply reel 35 to a take-up reel 36. Right next to the magnetic tape 31 are the magnetizing plates 37, the are connected to a unit with the magnetic tape container 32. In the arrangement shown is the combination of the magnetography supply tape designed with the magnetization device in such a way that the magnetization device is not a single plate, but a Magnetizing U-yoke 38 is used.

This not particularly difficult combination of a magnetography tape greater length with the magnetization device, e.g. for the weld seam, is carried out by hand along the weld seam to be tested drove. The magnetic tape splits exactly according to the tested weld seam length.

After testing a weld seam length of e.g. 10, 20 or 30 m If the magnetic tape runs through an electronic interrogation head, a depth of error is recorded in a desired .Massstabsverkleinerung is received as a test document.

The significant advantage of this method compared to the previous magnetic powder method is the separation of the test process and Interpretation of the test result as well as the objectification of the test, which is carried out at a considerably greater speed than the earlier powder test is to be carried out.

Instead of rewinding a magnetography supply tape during testing, can do that for certain, more stationary test tasks than endless ones Magnetography tape arranged in a loop on the body to be tested pressed continuously while revolving up during this revolving one point the tape is scanned by the rotating tape head, while it is scanned again after being polled by a magnet arrangement is brought to saturation, thereby removing the previous magnetographic recording is completely deleted. With this endless magnetography loop is the magnetization device at the same time coupled. 209820/0114

- ₁₉ -. 20A4535

This combination of circulating magnetography tape with the Alternating field magnetization device is explained using the example of the inspection of so-called fin tubes for external faulty doors will.

The fin tube 41 in Fig. 5 runs under your endless magnetography belt 42 by, while-the fins 43 of the alternating field magnetization of the magnetizing plates 44 are exposed. By a pressure roller 45, the magnetographic tape 42 is the profile of the Fin tube 41 adapted.

The rotating sound head 46 scans the magnetographic tape 42 line by line errors can be indicated by a signal and marked by a paint spray gun. Then j3a becomes the magnetic tape saturated in the loop in the saturation head 47 and deleted at the same time.

While so far fin tubes are magnetized for external defects by clamping high-current clamps over pieces of 1 m and thereby with Magnetic powder emuxsion were flooded with this process was to be repeated successively over the entire fin tube length of 12 to 15 m, can be seen in the arrangement of FIG. 5 continuously check the fin tube for external defects, which are signaled electronically.

The advantage of the | is also evident in the profile of the fin tube Error checking with magnetizing plate and saturated magnetic tape. During magnetization by direct or alternating current flow The method results in errors in the sharp rounding at the transition from the tube and fin to be reproduced more weakly the alternating field magnetization plate with saturated magnetic tape on all points of the fin tube for the same deep error the same error reproduction.

In a similar way, welds, among other things, can be started Check profiles for cracks during the welding process. Included becomes the magnetography test unit, consisting of circumferential dam endless magnetic tape, interrogation and saturation head as well as interchangeable

209820 / 01U

- 20 - 20A4535

Field magnetization plates ~ here, expediently in Yoke shape - behind the generally automatic welding device switched, which signals welding errors once v / earth, but also, if desired, a registered document is obtained, which is often the case with complex units is desired for acceptance reasons.

209820 / 01U

Claims (1)

Claims ( X) J Arrangement for non-destructive testing of steel parts ^ ** ^ with the help of the magnetic leakage flux exiting from the surface of the magnetized steel part at defect or-cen, characterized in that ferromagnetic plates are provided for magnetizing the steel part, which are attached to the steel part to be tested or are arranged adjacent to the area to be tested of this steel part, that the strength of the ferromagnetic plates is preferably low compared to the strength of the steel parts to be tested and that for the magnetic excitation of the ferromagnetic plates, a winding through which alternating current flows ment are surrounded. 2) arrangement for non-destructive testing of steel parts according to claim 1, characterized in that a device to set the frequency of the alternating current that the ferromagnetic plates magnetize the test pieces excited, is provided. 3) arrangement for non-destructive testing of steel parts according to claim 1, characterized in that the alternating current, the ferromagnetic plates to magnetize the test! Ie energized, is taken from the AC network. 4) arrangement for non-destructive testing of steel parts according to one of claims 1 to 3, characterized in that by placing a U-shaped core made of ferromagnetic, for example Shem material on the ferromagnetic plates for magnetization of the test parts a magnetic return is formed for the plates mentioned. 5) arrangement for non-destructive testing of steel parts according to one of claims 1 to 3, characterized in that the ferromagnetic plates for magnetizing the test pieces 209820 / 01U . _22nd 20U535 merge into one another on their side facing away from the test part and form a yoke-like unit. ■ * 6) arrangement for non-destructive testing of steel parts according to one of the preceding claims, characterized in that that the magnetizing unit for magnetizing steel parts from freely movable, alternating-field excited plates consists, which apply to the continuous test part by spring arrangement and roller arrangement, with rollers, which are attached to the fine-generating plates, for a constant Ensure the distance between the test part and the field-generating plates when the test part passes through. 7) Arrangement for non-destructive testing of νο, η steel parts according to one of the preceding claims, characterized in that the alternating field-excited plates with capacitors on the growing frequency of the exciting current in the vicinity The resonance can be adjusted so that when the air gap between the alternating magnetization plates and the test material is enlarged the alternating voltage on the alternating-field-excited plates increases so that the tangential field strength on the test material invariant to the size of the air gap between alternating field plates and test material works. 8) arrangement for non-destructive testing of steel parts according to one of the preceding claims, characterized in that that the steel parts are square billets, that a test chamber is provided, that a transport device is provided that pushes the billets in an axial direction in a continuous passage through the test chamber, that a spray device is arranged in the test chamber, which is suitable for applying fluorescent magnetic powder to the surface of the billet while it is being magnetized, that furthermore a blowing device is arranged in the test chamber, which is also suitable during the magnetization of the stick the said magnetic powder from the flawless parts of the stick bar surface to blow that on 209820/0114 lamps are attached to both Ee iv.cn of the test chamber / the Emit ultraviolet light and enable the detection of magnetic powder beads stuck at faults. 9) arrangement for non-destructive testing of steel parts according to claim 8, characterized in that a device for axially rotating the billet by 90 ° is provided that an automat! Initiates a 90 ° rotation through the test chamber and the return transport of the billet and this game is repeated until all four sides of the billet are a could be checked. 10) arrangement for non-destructive testing of steel parts according to claim 9, characterized in that the tester by means of an operating panel, the movement of the test material during the automatic run through the test channels is arbitrary can stop and reverse. 11) Arrangement for non-destructive testing of steel parts according to claim 9 or 10, characterized in that a rolling seat is provided for the examiner, which allows him without to stand up with his seat on either side of the test chamber to roll to move the magnetic powder caterpillars back and forth f of the stick to be tested while sitting and to mark it. 12) arrangement for non-destructive testing of steel parts according to claim 8 or 9, characterized in that for automation of the color marking the magnetic powder beads that glow in the ultraviolet light through rotating photocells in An electrical signal can be converted, whereby the width of the billet to be tested is divided into channels, which paint spray guns which are triggered by the fctocell impulses generated by the powder caterpillars that light up so that the powder beads are fixed by a color marking at the location of the defect. 209820 / 01U 3.3) arrangement for non-destructive testing of Etahlteile according to claim 8, characterized in that a second
Prüfkainnier similar to the ersuen it is provided that the transport device is capable of successively pushing the stick through
to push both test chambers so that fluorescent magnetic powder is applied to two opposite sides of the billet in each of the two test chambers, so that all four billet sides are scanned by photocells in one pass. 14) Arrangement for non-destructive testing of steel parts according to one of claims 8 to 13, characterized in that immediately after the respective magnetic powder spray, each fe still in the area of action of the magnetizing plates, which
Magnetic powder beads by spraying a corresponding
quick-drying liquid to be fixed. 15) arrangement for non-destructive testing of steel parts according to claim 14, characterized in that the magnetic powder is added or deposited with a substance which with
the fixation fluid enters into a physical and / or chemical reaction that leads to reinforcement and thus to improvement the detection of the normally very narrow powder beads
serves. 16) Arrangement for the failure-free defect checking of steel parts W according to one of claims 1 to 7, characterized in that an endless magnetic belt is provided which rolls on the steel part magnetized by the magnetizing plates and
the error stray fluxes of the steel part picks up and stores that an interrogation head is provided, which transversely to the magnetic tape
rotates, this scans and the stored in the magnetic tape
Converts leakage fluxes into electrical signals that paint spray guns are placed over the steel part by
the electrical signals are actuated so that an erasing device is provided which erases the magnetic tape after it has been interrogated and makes it ready for new leakage flows. 209820 / 01U 17) Arrangement for non-destructive spring testing of steel parts according to claim 16, characterized in that for the erasure of the magnetic tape in the magnetography process with alternating field magnetization a saturation magnetization is applied in the longitudinal, transverse or normal direction of the magnetic tape, in order to display only the effect of one of the two directions of magnetization of the alternating field magnetization. 18) arrangement for non-destructive testing of steel parts according to claim 16 or 17, characterized in that a Counting device is provided, which counts the error pulses when scanning the magnetic tape for a test part or a specific The number of test parts is counted electronically in order to determine the J display or print out the entire error length of one or a certain number of test parts for quality identification. 19) arrangement for non-destructive testing of steel parts according to one of claims 16, 17 or 18, characterized in that that the leakage fluxes picked up by the magnetic tape ■ after line-by-line scanning by the scanning head and conversion into electronic impulses to control mechanisms for eliminating errors, e.g. by grinding out or flaming out, be used. 20) Arrangement for non-destructive testing of steel parts according to one of claims 1 to 7, characterized in that I that a supply reel, a take-up reel and a pressure roller made of foam rubber or the like are provided, furthermore a magnetically saturated magnetic tape, which is from the pressure roller the area to be tested, e.g. a weld seam, is pressed so that when the pressure roller is moved forward the magnetic tape unrolls over the area to be tested and is rewound from the supply reel to the take-up reel that the area to be tested is at the point of contact with the magnetic tape through the ferromagnetic plates is magnetized so that at the same time the leakage flux of the area to be tested is absorbed by the magnetic tape and is stored that furthermore for the evaluation of the magnetic 209820 / 01U tape, a scanning unit is provided which is suitable for reading the leakage fluxes stored in the magnetic tape as electrical Display pulses on a fluorescent screen and / or by means of a pen in the desired geometric shape Scale reduction on a recording strip as To hold the document. 21) arrangement for non-destructive testing of steel parts according to claim 20, characterized in that the magnetic tape rewinding arrangement in combination with the alternating field magnetization through permanent magnetic adhesive rollers on the surface the area to be tested is recorded. 22) Arrangement for the non-destructive FeMer test of steel parts according to one of claims 1 to 7, characterized in that that an endless magnetic tape is provided, which is on the area magnetized by the magnetizing plates of the steel part unrolls and picks up and stores error stray fluxes that an interrogation head is provided, which transversely to the Magnetic tape rotates, scans it and converts the leakage fluxes stored in the magnetic tape into electrical signals, that a recorder is provided that records the error signals on a recording strip, that the paper feed this recorder is synchronized by the movement of the unwinding magnetic tape that an erasing device is provided which erases the magnetic tape after it has been scanned by magnetic saturation and makes it ready for recording again new error leakage flows. 23) Arrangement for non-destructive testing of steel parts according to one of claims 16, 17 or 18, characterized in that the magnetography arrangement, consisting of circumferential endless magnetic tape, scanning head and erasing head with magnetization unit a welding process, e.g. a profile welding, is connected directly downstream for continuous monitoring of its quality, in addition to error display and Defect marking also receive a defect registration as an acceptance document ict. 209820/0114