DE19915203C2 - Method and device for the non-destructive testing of steel that is to be rolled and is still easily deformable for internal defects - Google Patents

Description

The invention relates to a method and an apparatus for non-destructive testing of still to be rolled, well deformed steel on internal defects using at least one Ultra sound test head.

The non-destructive material testing using ultrasound is known for a long time.

For example, EP 0 202 134 B1 is a device in which the metal skin of aircraft on material mistake ler is examined, within a role that is about the object to be examined is moved, an ultrasonic probe is arranged.

Furthermore, a device is known from US-A-3 620 061, where an ultrasonic probe integrated in a roll is provided, the vibration energy when rolling sheets should generate, which should serve the load during rolling process to reduce.

Furthermore, DE 30 45 581 A1 integrates a role Grier ultrasonic probe disclosed in the paper position continuously the proper condition of the paper web should detect.

Finally, a method is described in DE 32 04 797 C2 ben, in which a finished workpiece, such as a pipe, is sonicated with a test head, the coupling of the  Sound energy over a water stretch between head and plant piece is effected.

Flaws in the workpiece are detected in the so-called ten pulse-echo method, that is, that of the test head sent sound on the one hand on the surface, on the other the back wall is reflected after the workpiece has been irradiated becomes. Two or more are formed in the display ger sharp pulses with a certain amplitude. The sound falls shaft within the workpiece for a defect (crack, on conclusion, etc.), it is also reflected at this point, and a third pulse is formed, the error pulse. Since the Sound energy several times between the defect and the test head and runs, is the subject of the cited document Process with which such additional, not of interest Impulses can be hidden, or impulses by possible contamination in the coupling medium. The Testing takes place on a finished workpiece under Be use of a liquid coupling medium in which - like him believes - also foreign objects that interfere with the measurements can be there.

The object of the present invention is, however, in the continuous nuclear processes during the rolling process such mistake to be able to track them inside the rolling stock. It means that the material to be tested is hot, so that the coupling over a liquid medium, for example water, not necessarily is feasible.

The steel to be rolled, for example in the form of bars, is especially produced in the continuous casting process, at the one that comes out of the mold, solidifies Strand is guided in an arc into the horizontal. As a result gravity accumulates in the liquid steel Foreign matter more in the area between the strand axis and the already solidified interior of the strand.  

In particular, these inclusions apply to the invention to detect processes during the rolling process.

According to claim 1, therefore, a method for destroying test of rolled, still easily deformable Steel for internal defects using at least one on / in the Steel rolling roller / roller arranged ultrasonic probe proposed, the ultrasonic waves being transmitted through the as a front running roller or roller body itself or a circumferential part of it will be sent before heading towards that test rolling material, being aligned in this way that they are in the area on the rolling material surface meet where the contact pressure of the roller / roller on the steel ma ximal, namely where the maximum back wall echo is achieved becomes.

The test site and the rolling location thus coincide, so that at the detection of significant errors can be reacted to quickly can.

It is aimed that the ultrasonic waves there on the Roll material surface hit where still intense in radial Direction is deformed, d. H. in the area of the entry point of the Rolled goods into the roll stand. Experiments have shown that a maximum back wall echo is achieved when the rolling stock is none Train is subjected, d. H. continue that a good synchronisa tion between the billets must be guaranteed.

Since the back wall echo is an indication of this good synchronization is between the blocks, consists of the inventive Method also the possibility by optimizing the re Wandechos a good synchronization between the blocks kidney.

Another advantage of the method according to the invention is that to see that the lead and coupling section through the Roll / roll itself is formed. This lead or Einkop The pel track is therefore suitable because of spontaneously changing absenteeism  len as in the liquid coupling medium mentioned above occur. In addition, the roller material, in particular in the close range, particularly fine-grained and faulty poor job.

At the interface from relatively cold roller / roller to hot Steel takes the first reflection of the sound waves, the not reflected part is due to the now different Broken speed of penetration to the perpendicular, passed the test object and will re at the opposite interface inflected. Are between first reflection and back Wall echo imperfections, especially inclusions, are the Sound waves are also reflected on these, resulting in reception part of the test head generates a pulse of a certain amplitude that is in the amplitude-time diagram between the two Edge reflection pulses.

According to claim 2, the ultrasonic waves on the Rolled material surface directed that after penetration of the Rolled material are reflected back to the recipient. As a result, the test material is completely scanned. The The test described is with both normal and S-E tests mind feasible.

Since imperfections in the edge area due to the finite width of the Reflection pulse by means of a probe, the longitudinal Emits sound waves that are perpendicular to the surface of the rolling stock meet and furthermore only a part of the test object radiating through, not being detectable, is inventive according to that, in particular in a multi-roll stand, in which the disc-shaped rollers / rollers around the Roll gap are arranged around (so-called Kocksblock), each these rollers are assigned at least one ultrasonic test head is. The arrangement of the test heads is made so that the Sound wave bundles of all probes cover the entire cross section of the Record the test object.  

The device works even more precisely and effectively when on an ul. on both sides of each of the disc-shaped rollers Traschallprüfkopf is provided.

However, this can also result in close defects in the rolled material be detected that the ultrasonic waves on the. Roll material surface are directed that they are in the rolling material near the surface are reflected several times along the circumference, before they get to the recipient.

The sender and receiver are separate from each other.

A device according to the invention is ge by claim 5 give.

To position the test heads are on the side of the panes shaped rolls / rollers either wedge-shaped in cross section Ring grooves milled or wedge-shaped ring shoulder in cross section molded on. The groove surface facing the roller circumference or Shoulder surface moves under the detec during rolling gate surface of the stationary probe, passing only a small gap filled with water between the head and Roller is present.

However, the device according to the invention is not only based on the Limited multiple-roll stands just described. According to claim 11 the test heads can also be used for profile rollers the one with the test heads next to the actual Chen roll gap positioned in these adjacent profile grooves and that these grooves and the roll gap separate Radiate through the rolling material as a lead section.

According to claim 12, two each point to different ones Ultrasonic probes arranged on either side of the roll gap diametrically opposite directions of sound propagation.

This arrangement is suitable for rolls with a flat edge profile.  

In the case of rollers with a spike edge profile, the test heads can be on the outside catch the rollers be positioned so that the sound the ge passes through the entire roll body before it hits the roll gap and thus meets the rolling stock.

Here too, several test heads can be provided, which Sonicate rolling stock from different sides.

As particularly suitable test heads for those described so far Applications with piezo transducers as sounders have been used proven producers.

To set the direction of sound, according to claim 15 be provided that the at least one ultrasonic probe pivotable in the rolling direction and / or perpendicular thereto and / or is movable.

Claim 14 offers an alternative to this. Claim 14 suggests that the at least one probe be a variety of Piezo vibrators that can be controlled independently of one another as a generator ger has a sound wave front.

The individual piezo oscillators are staggered in time the driven. Depends on the time difference a sound wave front with different propagation direction.

According to claim 16 it can be provided that the coupling surface of the ultrasonic probe (s) convex or concave bulges, which results in a focus or defocus which results in sound waves.

Preferably, according to claim 17, the front according to the invention go ahead on the finishing stand of the rolling mill arranged the roll stand.

At this point there is good ductility of the rolling stock in front. However, it is particularly important that the device  needs to be adjusted only once, so that the assembly and Adjustment effort is reduced to a minimum.

The device can with longitudinal ultrasonic waves also work with transverse ultrasonic waves.

This is particularly advantageous because through appropriate ver Ultrasound courses with appropriate selection of the single beam angle using both transverse and longitudinal flaws that run radially are detected can be.

The invention is illustrated below with reference to a drawing provides and explained in more detail.

Show it:

Fig. 1: traschallprüfköpfen truncated representation in a multi-roll stand with three different alternatives of the arrangement of Ul,

FIG. 2 shows a schematic representation of the arrangement of ultra schallprüfköpfen with profile rollers (flat edge),

Fig. 3: a schematic representation of the arrangement of ultra sound probes in profile rollers (spike edge).

In Fig. 1, a three-roll stand is schematically Darge and generally provided with the reference numeral 1 .

Three disk-shaped rollers 3 a, 3 b, 3 c are arranged in a star shape around the circular nip 2 in this example, the axes of rotation of the rollers being designated by 4.

In the roller 3 a two alternative arrangements of only schematically shown ultrasonic probes 5 are shown. The coupling surface 6 is carried to the left on the roller 3 a formed-through to the side of the roll 3 a wedge-shaped in cross-section annular shoulder 7, while the right is realized by a molded in the roll side (milled) in cross-section wedge-shaped annular groove. 8

The orientation of the coupling-in 6 is in each case so selected that the sound waves generated and the ultrasonic probes 5 are received, genes longitudinal type perpendicularly incident on the in the nip 2 rolling located after a have passed through the periphery near part of the roll. 3

As with the roller 3 c only indicated, the direction of expansion of the sound waves can also be modified so that they meet the surface of the rolling stock at an angle different from 90 ° and then run close to the edge of the specimen under multiple reflection at the interface.

A third alternative, the coupling of ultrasonic waves is shown in b of the roller. 3 Here, an annular shoulder with a trapezoidal cross section is placed on the side of the rollers, the inclined surface being the coupling surface 6 bil det. The positioned on this coupling surface 6 ultrasonic probe 5 emits transverse ultrasonic waves, which are broken at the interface between the ring shoulder and roller 3 b so that they also meet perpendicularly to the surface of the rolling stock.

All three rollers 3 a, 3 b and 3 c can be equipped on both sides with one of these alternatives or with combinations thereof.

In FIG. 2, the arrangement of the ultrasonic transducers 5 is shown in a Profilwalzartlage. A flat edge profile 11 is rolled. In addition to the profile groove forming the roll gap 2, there are further profile grooves 12 in the roll 3 ', the ultrasound probes which radiating the roll material horizontally and the direction of sound propagation on both sides of the roll gap 2 being arranged on / in the profile walls facing the roll gap 2 arranged ultrasound probes 5 are diametrically opposite.

In Fig. 3, finally, the arrangement of the ultrasonic probes 5 is shown on a profile rolling system that rolls spit edge profiles.

The roll gap 2 is formed here by cross-sectionally triangular profile grooves 13 , 13 tere similar profile grooves are provided in addition to this profile groove.

The ultrasonic test heads 5 are located here on the side of the profile rolls 3 'facing away from the roll gap 2 , so that the sound waves emitted by them radiate through the entire roll body before they hit the rolling stock perpendicularly.

The ultrasonic probes 5 are preferably positioned on different sides of the roll gap 2 on / in the flanks 14 of the profile grooves.

In all the cases described, the test heads 5 are arranged in a stationary manner, while the rollers 3 , 3 'or the coupling surfaces 6 run past the test head. A water film 15 is located between the test head 5 and the coupling surface 6 .

The coupling point of the sound waves into the rolling stock to be tested is preferably located immediately behind the entry point of the rolling stock in the roll gap, i.e. where the roll and roll good surface are in intimate contact with each other.

The test device is arranged on a roll stand, which is positioned in front of the finishing stand in the rolling process.

Claims (18)

1. Procedure for the non-destructive testing of rolling steel that is still easily deformable on internal defects by means of min at least one on / in the steel roller / roller ordered ultrasound probe, the ultrasound waves through the roller / Roll body itself or a part of it close to the circumference are sent before they are placed on the rolling mate to be tested rial, aligning them so that they hit the rolled material surface in the area, where the contact pressure of the roller / roller on the steel is maximum is there, where the maximum back wall echo is achieved becomes. 2. The method according to claim 1, characterized, that the ultrasonic waves are so on the rolling stock surface that after penetrating the rolling material than be reflected back to the recipient. 3. The method according to claim 1, characterized, that the ultrasonic waves are so on the rolling stock are directed that they surface in the rolling material  are repeatedly reflected along the circumference, before they get to the recipient. 4. The method according to any one of claims 1 to 3, characterized, that the at least one ultrasonic probe is longitudinal Emits ultrasonic waves. 5. The method according to any one of claims 1 to 3, characterized, that the at least one ultrasonic probe is transverse Emits ultrasonic waves. 6. Device for the non-destructive testing of the still easily deformable steel to be rolled for internal defects by means of at least one ultrasound test head, characterized in that the at least one ultrasound test head ( 5 ) on / in at least one of the rolls / rollers involved ( 3 a , 3 b, 3 c, 3 ') is arranged such that the roller / roller body itself or a part thereof close to the circumference forms the lead section for the ultrasonic waves before they strike the rolling material to be tested, and the at least one ultrasonic Test head ( 5 ) is designed as a transmitter and / or receiver and its orientation is selected such that the ultrasonic waves hit the surface of the rolling material in the area where the contact pressure of the roller / roller ( 3 a, 3 b, 3 c, 3 ' ) is maximum. 7. The device according to claim 6, characterized in that the rolling device is a multi-roll stand, in which the disc-shaped rollers / rollers ( 3 a, 3 b, 3 c) are arranged around the roller gap ( 2 ) and each of these rollers / Rollers ( 3 a, 3 b, 3 c) is assigned to at least one ultrasonic probe ( 5 ). 8. The device according to claim 7, characterized in that on each side of each roller / roller ( 3 a, 3 b, 3 c) at least one ultrasonic probe ( 5 ) is arranged. 9. Device according to one of claims 6 to 8, characterized in that the / the ultrasonic test head (heads) ( 5 ) in the laterally in the rollers / rollers ( 3 a, 3 b, 3 c, 3 ') molded ring grooves ( 8 ) is / are positioned. 10. Device according to one of claims 6 to 8, characterized in that the / the ultrasonic test head (s) ( 5 ) on the side of the rollers / rollers ( 3 a, 3 b, 3 c) integrally formed annular shoulder-like projections ( 7 ) is / are positioned. 11. The device according to claim 6, characterized in that the rolling device consists of two profile rollers ( 3 ') and the / the ultrasonic test head (s) ( 5 ) is arranged laterally so that the sound waves in the right angle the roll gap wall ( 2 ) formed by the profile are aligned. 12. The apparatus according to claim 11, characterized in that two ultrasound probes ( 5 ) arranged on different sides of the roll gap ( 2 ) have diame tral opposite sound propagation direction. 13. Device according to one of claims 6 to 12, characterized in that the at least one test head ( 5 ) has a piezo oscillator as a sound generator. 14. The device according to any one of claims 6 to 13, characterized in that the at least one test head ( 5 ) has a plurality of independently controllable piezo oscillators as he has a sound wave front. 15. The device according to one of claims 6 to 14, characterized in that the at least one ultrasonic test head ( 5 ) in the rolling direction and / or perpendicular to it is pivotable and / or displaceable. 16. The device according to one of claims 6 to 15, characterized in that the coupling surface of the / the ultrasonic test head (s) ( 5 ) is convex or concave. 17. The device according to one of claims 6 to 16, marked by the arrangement on a finishing stand of the rolling mill preceding mill stand. 18. Device according to one of claims 6 to 17, characterized in that between the ultrasonic probe ( 5 ) and the roller / roller assigned to it ( 3 a, 3 b, 3 c, 3 ') or the Ankoppelflä surface Water film ( 15 ) is located.