JP6287943B2 - Center misalignment detection apparatus and center misalignment detection method - Google Patents

Description

  The present invention relates to a technique for detecting a misalignment when rolling a steel material made of a rod or wire.

Conventionally, for example, there is an apparatus described in Patent Literature 1 as detection of misalignment during rolling. In this apparatus, the misalignment of the rolling line is measured before rolling using a laser light source and a light receiver.
However, even if the rolling roll is centered before operation by the method as described in Patent Document 1, the guide roll for guiding the steel material to the hole mold of the rolling roll is displaced, so that the holes of the rolling roll forming a pair There is a case where the steel material passing through the mold causes core misalignment. If the steel material comes into contact with the rolling roll due to the misalignment, the rolling accuracy of the steel material is deteriorated accordingly. In particular, the influence becomes large during finish rolling.

  For this reason, in the past, on the outlet side of the rolling mill, which is the target during rolling operation, the worker works against the high-temperature steel (hot-rolled steel) moving out of the rolling mill and moving along the pass line. However, by pressing the wood for detecting misalignment and collecting the baking mold, the actual misalignment of the steel relative to the rolling roll is detected according to the condition of the firing mold, and the target misalignment is eliminated. The position of the guide roll or rolling roll on the entrance side of the rolling mill is adjusted.

  Here, the wood misalignment detection wood piece is, for example, a rectangular wood piece, and by pressing one side of the wood piece against the hot-rolled steel material, the wood piece in contact with the hot-rolled steel material has an outer contour of the steel material. A corresponding arc-shaped burn mark (baking mold) remains. The pressing position is performed around the non-pressed surface portion after being rolled. At this time, when the core of the guide roll is not in contact with the core of the rolling roll facing the rolling mill, a deviation occurs in the width of the oval portion remaining in the baking mold of the piece of wood, and the misalignment is detected from the deviation. It is possible.

However, core misalignment detection using a core misalignment detection wood piece is a simple method, but an operator approaches the hot rolled steel material being transported during rolling, that is, the hot rolled steel material being moved. Skill is required to collect the baking mold by pressing the piece of wood. Moreover, it becomes a work accompanied by danger because a piece of wood is directly pressed against the hot-rolled steel material being moved.
The detection of misalignment as described above is an operation that occurs every time the roll or guide roll is changed according to the target steel material.

  On the other hand, Patent Document 2 discloses a technique for capturing an uncompressed lower surface portion with a camera and detecting a misalignment based on the captured image.

JP 2006-55861 A JP 2008-126244 A

In Patent Documents 1 and 2, there is a possibility that the lens of the camera is contaminated by water, scales, and the like around the rolling mill. That is, there is a possibility that long-term imaging may become difficult because the lens of the camera is affected by water flew from a steel material or the like and a drop scale.
The present invention has been made paying attention to the above points, and has an object to make it possible to more stably perform misalignment detection while suppressing interference with other rolling equipment.

  In order to solve the above-mentioned subject, one mode of the present invention is directed to the above-mentioned rolling roll of the steel material when rolling a steel material made of a wire or a bar sent along a pass line with a pair of rolling rolls. A misalignment detecting device for detecting misalignment, comprising a guide portion for guiding a steel material rolled with the pair of rolling rolls with a guide hole made of a through hole, and the steel material rolled with the pair of rolling rolls A steel surface including a non-crushing surface forming a pair positioned between the crushing surfaces forming a pair that is reduced by the pair of rolling rolls on the surface is used as a detection surface, and each of the detection surfaces is formed on the guide portion. A slit that faces the detection surface, a camera that images the detection surface of the steel material in a non-contact manner through the slit, and a gap between the slit and the camera. A box that covers the opening on the camera side of the slit and that overlaps the imaging area of the camera that images the detection surface through the slit, and a gas that pumps a purge gas into the box And a pumping unit.

According to one aspect of the present invention, an image of the detection surface is captured from a limited space called a slit provided in the guide portion, and an image is captured by the camera while performing an air purge by gas injection from the slit. Reduce the effects of water and falling scale. As a result, it is possible to detect the detection surface including the non-pressing surface easily and stably.
And it becomes possible to reduce interference with another rolling equipment by providing a slit in the guide part which guides steel materials, and imaging.
From the above, according to one aspect of the present invention, it is possible to more stably execute misalignment detection while suppressing interference with other rolling equipment.

It is a schematic block diagram which shows the hot rolling line which concerns on embodiment based on this invention. It is a figure which shows the example of the arrangement | positioning relationship of each part seen from the rolling mill delivery side which concerns on embodiment based on this invention. However, only one upper and lower camera is shown. It is sectional drawing seen from the side which concerns on the misalignment detection apparatus which concerns on embodiment based on this invention. It is the figure seen from the rolling direction cut | disconnected in the slit position which concerns on embodiment based on this invention. It is a typical perspective view which shows the relationship between a guide hole and a slit. It is a perspective view of the food | hood which has a slit. It is a figure which shows the example of the detection surface of the steel material surface by the side of a rolling mill.

Next, embodiments of the present invention will be described with reference to the drawings.
Drawing 1 is an outline lineblock diagram showing hot rolling equipment of a bar steel concerning this embodiment.
Here, the steel material which is the object of the present invention is not limited to a steel bar or other bar material, but can be applied to a wire material. However, in the following embodiment, a case of rolling to a steel bar will be described as an example.
(Constitution)
As shown in FIG. 1, a steel material 1 made of a bar material heated in a heating furnace is rolled in order by a plurality of rolling mills A to # 16 to be formed into a target bar shape. In the present embodiment, the rolling mill is an example in which 18 stands are arranged in parallel, and the 12th stand, the 14th stand, or the 16th stand is set to be the final finishing stand depending on the diameter or material of the steel material 1. ing.

  As shown in FIG. 2 which is a schematic diagram, each rolling mill is rolled by two rolling rolls 3 and 4 which form a pair in the vertical and horizontal directions. In each of the rolling rolls 3, 4, a hole mold corresponding to the steel material 1 is formed. In addition, guide rolls 5 each consisting of a pair of guide rolls are arranged on the entry side of the respective rolls 3 and 4, and the steel material 1 sent along the pass line is rolled by the guide rolls 5. , 4, and then rolled by the opposed hole molds of the pair of rolling rolls 3, 4 and sent toward the exit side. The opposing direction of the pair of guide rolls 5 is arranged 90 degrees away from the opposing direction of the corresponding pair of rolling rolls 3 and 4. For example, when the rolling rolls 3 and 4 are arranged up and down, the guide portions are arranged on the left and right.

  In addition, the direction of the rolling rolls 3 and 4 of each stand is arranged 90 degrees away from the direction of the rolling rolls of the preceding stage stand. That is, the direction of the rolling rolls 3 and 4 of each stage stand has a configuration in which the vertical direction and the horizontal direction are alternately arranged. And in this embodiment, it is set as the case where the rolling rolls 3 and 4 which make a pair in the 12th stand used as the last stand, the 14th stand, and the 16th stand are opposingly arranged right and left.

  And the guide part 10 which guides the rolled steel material 1 is provided in the exit side of the rolling mill which comprises the 12th stand, 14th stand, and 16th stand which can become the finish rolling mill. In addition, the housing of the guide part 10 of this embodiment has a substantially rectangular parallelepiped shape. In the present embodiment, a camera 6 for detecting misalignment is installed in the vertical direction outside the guide portion 10 in the radial direction.

  As shown in FIGS. 3 to 5, a guide hole 11 is formed in the guide portion 10. The guide hole 11 extends along the pass line P and includes a through hole having a size allowing the steel material 1 to be loosely inserted. The guide hole 11 has a substantially cylindrical shape with a circular cross section, but the inlet side portion 11a of the guide hole 11 is tapered so that the steel material 1 can be guided inside as shown in FIG. That is, the inlet side portion 11a of the guide hole 11 becomes larger in diameter toward the opening of the inlet.

In addition, you may provide the air hole 28 separately like FIG.
A pair of slits 12 are formed in the guide portion 10 with the guide hole 11 interposed therebetween.
The rolling rolls 3 and 4 of this embodiment roll from right and left. For this reason, the pair of slits 12 of the present embodiment opens on the upper surface and the lower surface of the guide hole 11, and each slit 12 extends in the vertical direction and opens on the outer wall (ceiling surface or bottom surface) of the guide portion 10. doing.

  Here, in the present embodiment, the pair of slits 12 are arranged so as to be positioned on the same plane, but the pair of slits 12 are offset from each other in the axial direction of the guide hole 11 (direction along the pass line P). It may be formed. In the present embodiment, each slit 12 is formed in a fan-shaped space that extends radially in the radial direction perpendicular to the guide hole 11. Depending on the relationship of interference with other equipment, each slit 12 may be formed so as to extend in a direction inclined forward and backward from the radial direction (axial direction).

  In the present embodiment, each of the pair of slits 12 is formed with respect to the guide unit 10 by incorporating the hood 20 having the slits 12 into the guide unit 10. FIG. 6 is a perspective view showing the configuration of the hood 20. The hood 20 has an insertion portion 20b and a base portion 20c. The insertion portion 20b is provided with an arcuate groove portion 20a having a size along the inner periphery of the guide hole 11 in the upper bottom portion of a member formed in a trapezoidal shape. The insertion portion 20b is inserted into a hood insertion slit 21 (see FIGS. 3 and 5) formed in the guide portion 10 so as to extend in the vertical direction with the guide hole 11 interposed therebetween. The base portion 20 c is a portion that is connected to the lower base side of the trapezoidal member that forms the insertion portion 20 b and is fixed to the guide portion 10. The slit 12 is formed so as to penetrate the base portion 20c, the insertion portion 20b, and the groove portion 20a of the hood 20. Then, the insertion portion of the hood portion 20 is inserted into the hood insertion slit 21 of the guide portion 10 so that the groove portion 20a is along the inner periphery of the guide hole 11, and in this state, the base portion 20c is fixed to the guide portion 10 with a bolt or the like. Thus, the slit 21 is formed in the guide portion 10.

  As described above, the slit 12 of the present embodiment opens in the guide hole 11, extends radially in the radial direction, and opens on the upper surface or the lower surface of the guide portion 10. Each slit 12 has the same axial dimension of the guide hole 11, but the circumferential dimension increases as the distance from the guide hole 11 increases. That is, each slit 12 has a fan shape when viewed from the axial direction of the guide hole 11, and the opening cross section increases as the distance from the guide hole 11 increases.

An air case 13 is provided so as to cover an opening portion opened to the upper surface or the lower surface of the guide portion 10 of each slit 12. Each air case 13 is a box that is open on the guide portion 10 side, covers the opening, and extends in the same direction as the slit 12.
Of the wall surface of the air case 13, the bottom surface facing the opening of the guide portion 10 is formed of a transparent body 13 a. The transparent body 13a is made of, for example, a transparent acrylic plate.

  In addition, a duct connection portion 14 is provided on the side surface of the air case 13, and an air compressor 16 is connected to the duct connection portion 14 via a pipe line 15. The air compressor 16 constitutes a gas pumping unit, and pumps air that is a gas into the air case 13. As a result, the space pumped into the air case 13 is injected from the slit 12 into the guide hole 11 with a predetermined injection pressure. Of course, a gas other than air may be used.

  In this embodiment, as shown in FIG. 3, a small slit-like opening 19 is also formed in the inlet side portion 11a of the guide hole 11, and air is jetted from the opening toward the upstream side. ing. The pressure feeding to the opening of the inlet side portion 11a uses a gas feeding mechanism different from the air case 13 and the air compressor 16, but may be realized using the same gas feeding mechanism. .

  A camera 6 for detecting misalignment is disposed outside the bottom surface of the air case 13. In the present embodiment, as shown in FIG. 4, three cameras 6 are arranged for each slit 12, that is, for each detection surface. As shown in FIG. 4, the imaging axis S of each camera 6 images the steel material surface in the guide hole 11 through the transparent bottom surface (transparent body 13 a) of the air case 13, the air case 13, and the slit 12. Is set to The imaging axes S of the three cameras 6 are arranged so as to be inclined with respect to each other by a predetermined angle in the circumferential direction of the steel material 1 around the pass line. Specifically, the center camera 6 is disposed with the imaging axis S oriented vertically, and the left and right cameras 6 are disposed so as to be inclined in the circumferential direction by, for example, 20 degrees in the left-right direction from the center camera 6. As a result, the left and right cameras 6 can image the upper surface side or the lower surface side of the steel rod from the direction inclined in the circumferential direction by 20 degrees with respect to the vertical direction.

Here, the camera 6 is housed in a housing 17 for the camera 6 opened on the guide portion 10 side, and each camera 6 is attached to the inner wall of the housing 17. The camera 6 is composed of a CCD camera, for example.
In addition, it sets so that the magnitude | size of the imaging screen in each camera 6 may become equal by setting so that the distance from the light-receiving part of all the cameras 6 to the steel material surface may become substantially equal. Further, the transparent body 13a constituting each bottom portion of the air case 13 is set to be a flat plate orthogonal to the imaging axis S of the camera 6 facing the air case 13.

As shown in FIG. 3, a thickness gauge 18 is attached to the exit side of the guide portion 10. And the diameter of the steel material 1 rolled by the rolling rolls 3 and 4 is measured by the thickness gauge 18 while being guided by the guide portion 10.
Each camera 6 images the upper surface side and the lower surface side of the steel material surface guided by the guide unit 10 on the exit side of the rolling rolls 3 and 4. That is, each camera 6 can image the detection surface, which is the steel material surface including the non-pressing surface 1a that is not in contact with the hole mold of the roll, from above and below.

The paired cameras 6 capture images in synchronization with a command from a control unit (not shown), and output the captured image data to an image display unit 7 made of liquid crystal or the like by wire or wirelessly.
There may be two image display units 7 for the upper camera and the lower camera for each camera 6, and two types of image data on the upper and lower sides are arranged side by side or superimposed on the display surface of one image display unit 7. It may be displayed. In the present embodiment, three cameras 6 are arranged on the upper side and three cameras 6 are arranged on the lower side. Therefore, when the upper and lower images are overlapped, the images of the cameras 6 that are subject to the axis are viewed from the pass line direction. It is better to overlap.

In the present embodiment, since the same detection surface is captured by the three cameras 6, the images of the three cameras 6 may be displayed as they are, and the width of the non-pressing surface with respect to the detection surface is large. Only an image may be displayed.
The display surface of the image display unit 7 is preferably provided with a scale. When the scale is displayed, the position and size of the displayed image can be easily recognized. As for the scale, a transparent sheet with a scale may be superimposed on the display surface, or the scale image and the input image may be superimposed on the image display.

(Operation other)
In the embodiment, the steel material 1 (hot-rolled steel material 1) coming out of the heating furnace is rolled in order by a multi-stage rolling mill, so that the outer contour of the cross section gradually approaches a circle from a polygon. Then, the steel material 1 rolled from above and below by the rolling mill of the final stand and guided from the rolling mill 10 is positioned by being guided by the guide portion 10, that is, in a state where the shaking is reduced, the diameter is measured by the thickness gauge 18. Is measured.

The guide portion 10 is configured such that the steel material 1 is guided to the center of the guide hole 11 by the taper of the inlet side portion 11a, and water adhering to the steel material surface by the gas sprayed obliquely upstream from the opening of the inlet side portion 11a. The steel material 1 is guided into the guide hole 11 while blowing off a falling scale or the like.
In this embodiment, when the steel material 1 is guided by the guide hole 11 of the guide part 10, the upper part and lower part of the surface are imaged with the camera 6 which makes a pair from the up-down direction, respectively, and the image is obtained. The image is displayed on the image display unit 7. FIG. 7 is an example of an image captured by each camera 6.

As described above, the steel material 1 is guided by the guide hole 11 so that the steel material 1 is positioned and the shaking of the steel material 1 is suppressed and the steel material surface is imaged by the camera 6. The state of the steel surface can be imaged with higher accuracy.
Further, although moisture or the like adhering to the surface of the steel material may fly in the direction of the camera 6 (outward in the diameter direction of the steel material), the camera 6 takes an image through a closed space through a specific gap formed by the slit 12. By doing so, it becomes difficult for moisture or the like to enter the camera 6 side, and by blowing gas from the slit 12 to the steel material 1 side, moisture or the like does not surely enter the slit 12.

Here, even when there is no gas injection from the inlet side portion 11a, when the gas injection speed from the slit 12 is set to 20 m / s or more, moisture can be prevented from entering the camera 6 for a long time. Have confirmed.
Further, since the opening cross section of the slit 12 is set to be smaller toward the guide hole 11, the gas injection pressure from the slit 12 into the guide hole 11 can be increased.

Here, since the steel material surface has a lower steel surface temperature of the non-crushing surface 1a than the pressing surface 1b rolled by the rolling rolls 3 and 4, on the rolling mill exit side, as shown in FIG. The non-pressing surface 1a on the surface can be visually recognized as a band-like portion having a different color from the pressing surface 1b.
For this reason, the upper surface image (detection surface image) and the lower surface image (detection surface image) of the steel surface displayed on the image display unit 7 are respectively belt-shaped non-pressing surfaces extending along the axial direction. 1a can be visually observed, and by measuring the width of the band portion, the position and size of the width of each non-pressing lower surface 1a paired up and down can be obtained.

  And if the width | variety magnitude | size of the non-pressing lower surface 1a which makes a pair up and down is the same, there is no centering up and down, the core of the rolling rolls 3 and 4 and the core of the guide roll 5 of the guide roll 5 Can be regarded as matching. On the other hand, if the positions of the widths of the uncompressed portions that form a pair at the top and bottom are different (biased), the core of the steel material 1 is shifted up and down with respect to the rolling rolls 3 and 4, that is, the rolling rolls 3 and 4 It can be considered that the core of the guide roll 5 is displaced up and down with respect to the core.

  For example, when viewed from the rolling mill exit side, when the steel material 1 is fed to the upper side of the cores of the paired rolling rolls 3 and 4 as shown in FIG. A relatively large number of the rolls of the rolling rolls 3 and 4 are brought into contact with each other and rolled. For this reason, the band of the non-pressing surface 1a in the imaged upper image is displayed with a small width. On the other hand, since the band of the non-cushion surface 1a appearing in the captured lower image is captured from the lower side, it is displayed with a larger width than the band of the upper non-cushion surface 1a. .

Thus, the amount of misalignment of the steel material 1 with respect to the rolling rolls 3 and 4, that is, the rolling roll of the guide roll 5 disposed on the entry side of the rolling rolls 3 and 4, due to the difference in the width of the non-pressed surface in the upper and lower images. The actual misalignment amount with respect to 3 and 4 is estimated, and the position of the guide roll 5 is adjusted based on the estimated value.
Here, the steel material 1 may be twisted while it reaches the measurement position by the camera 6 after leaving the rolling mill. In this case, if the opposing direction of the pair of cameras 6 is installed only in the direction perpendicular to the rolling direction of the rolling mill, and the imaging axis of the camera 6 is only in the direction perpendicular to the rolling direction of the rolling mill, the steel material 1 is twisted. Depending on the degree, the width of the band of the non-pressing surface 1a is small and the image is taken. When the width of the band of the non-pressing lower surface 1a becomes small, even if there is a difference in the width of the non-pressing lower surface 1a that forms a pair, it becomes difficult to recognize the difference from the captured image. In this embodiment, since the three pairs of cameras 6 and 6 in which the imaging axis S is inclined with respect to each other in the circumferential direction of the steel material 1 are provided, when the above-described twist occurs in the steel material 1, any pair of cameras 6 and 6 are provided. It is possible to avoid an image captured by the cameras 6 and 6 being captured with a small width of the band of the non-pressing surface 1a. Therefore, among the three pairs of picked-up images, if the pair of images picked up with the largest width of the non-crushing surface 1a is selected, even if the above-described twist occurs in the steel material 1, it is selected. It becomes possible to easily recognize the difference in the width of the non-pressing lower surface 1a forming a pair from the pair of images.

As described above, since the misalignment is detected in a non-contact manner with respect to the hot-rolled steel material 1, it is safe, and the misalignment can be detected easily and accurately.
In addition, for example, since the misalignment is measured visually and the guide adjustment is performed manually, the image display unit 7 is set near the rolling line and in a place considered to be safe so that the position adjustment can be performed early. Good.

Here, although the CCD camera 6 is illustrated as the camera 6, the embodiment detects not a shape of the steel surface but a temperature difference, so that a heat sensing camera such as an infrared camera may be used.
In the embodiment, the centering process at the final stand is exemplified. However, in the rolling mill other than the final stand, the guide unit 10 is arranged at the exit side position and the camera 6 that makes a pair is installed. Centering may be performed by the above detection method.

  Further, as described above, since the misalignment is detected based on at least the bias of the non-pressing lower surface 1a, the misalignment is determined based on the size (width) of the non-pressing lower surface 1a in the image captured by one camera 6. However, in the present embodiment, in consideration of the vibration of the steel material 1 and the like, the misalignment is detected by relative evaluation regarding the width of the upper and lower unstressed surfaces 1a, and the accuracy of the misalignment detection is detected. Has improved.

  Furthermore, in this embodiment, by disposing the three cameras 6 with respect to the detection surface including each non-pressing surface by shifting each other by a predetermined angle (for example, a range of 10 degrees to 30 degrees) in the circumferential direction of the steel material, Even when the position of the non-pressurized lower surface 1a is displaced from the vertical direction, the accuracy of detecting the misalignment is improved by displaying the width (band) of the non-compressed lower surface 1a with higher accuracy. For example, in the case of simple confirmation by visual recognition or the like, it is only necessary to evaluate by applying an image having the widest width (band) of the non-pressing surface 1a among the images of the three cameras 6.

Here, in the embodiment, a description is given assuming a still image as a captured image of the camera 6, but a moving image may be used. The position of the guide roll 5 or the like may be adjusted while continuously confirming the difference between the widths of the detection surfaces that are paired up and down in real time.
In addition, the captured image captured by each camera 6 may be subjected to image processing by the image control unit, and the above-described width and position deviation may be converted into numerical values and output.

DESCRIPTION OF SYMBOLS 1 Steel material 1a Non-pressed surface 1b Compressed surface 3, 4 Rolling roll 5 Guide roll 6 Camera 7 Image display part 10 Guide part 11 Guide hole 11a Entrance side part 12 Slit 13 Air case (box)
13a Transparent body 14 Duct connection portion 15 Pipe line 16 Air compressor 17 Housing P for camera P Pass line S Imaging axis

Claims (6)

A misalignment detection device for detecting misalignment of the steel material with respect to the rolling roll when rolling a steel material made of a wire rod or a bar material sent along a pass line with a pair of rolling rolls,
The steel material rolled by the paired rolling rolls is provided with a guide portion that guides through a guide hole made of a through hole,
A steel surface including a non-crushing surface forming a pair located between a crushing surface forming a pair that is rolled down by the rolling roll that forms a pair on the surface of the steel material rolled by the rolling roll that forms the pair, and a detection surface, respectively.
A slit that is formed in the guide portion and that opens on the wall surface of the guide hole that can face each of the detection surfaces, and faces the detection surface;
A camera that images the detection surface of the steel material through the slit in a non-contact manner;
A box that is interposed between the slit and the camera, covers a camera-side opening of the slit, and overlaps with an imaging region of the camera that images the detection surface through the slit;
A gas pumping section for pumping a purge gas into the box;
A misalignment detecting apparatus comprising: The guide hole has a circular cross section,
The slit is formed in the wall surface of the guide hole so as to extend in the circumferential direction of the guide hole, and is formed so that a cross-sectional area becomes smaller as it approaches the wall surface of the guide hole. The misalignment detection device described in 1. The number of cameras for imaging the detection surface is three or more for one detection surface, and the cameras are arranged at intervals along the circumferential direction of the steel material. The misalignment detection apparatus according to claim 2. A core misalignment detection method for detecting a misalignment of the steel material with respect to the rolling roll when rolling a steel material consisting of a wire rod or a bar material sent along a pass line with a pair of rolling rolls,
The steel material rolled by the paired rolling rolls is provided with a guide portion that guides through a guide hole made of a through hole,
A pair of steel surfaces including a pair of non-crushing surfaces located between the squeezing surfaces formed by the paired rolling rolls on the surface of the steel material rolled by the paired rolling rolls are imaged by a camera. Then, the image is used as a detection surface, and a misalignment is detected based on a difference in the width of the non-pressing surface on the pair of detection surfaces,
Each of the detection surfaces can be imaged by the camera through a slit formed in the guide portion and opened in the wall surface of the guide hole so as to be opposed to the detection surfaces.
A method of detecting misalignment, wherein a purge gas is pumped into the slit, and the gas is ejected from the slit toward the steel surface to perform air purge.   5. The misalignment detection method according to claim 4, wherein the slit is set so that a cross-sectional area becomes smaller as it approaches the opening of the wall surface of the guide hole. The number of cameras for imaging the detection surface is three or more with respect to one detection surface, and the cameras are arranged at intervals along the circumferential direction of the steel material. The method for detecting misalignment according to claim 5.

Images