JPH0467888B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention can detect the position of a hot metal lump in the width direction even if disturbances such as water or steam block the field of view of the detector. The present invention relates to a method and apparatus for detecting the widthwise position of a metal lump, which enables the width end position of the metal lump to be detected with high precision.

[Prior Art] In rolling or continuous processing, precise sheet width control is desired in order to improve product yield. Particularly in the case of hot rolling, horizontal rolling in a rolling mill causes the rolled material to widen in width, but if this is left as is and rolling is repeated, the width of the product will be much larger than the set value, resulting in side The portion to be cut off due to trimming or the like increases, resulting in a decrease in yield.

On the other hand, meandering tends to occur in reverse rolling on a single stand and in tensionless rolling when passing the leading and trailing ends on a continuous stand, so it is necessary to detect the amount of meandering in the rolled material and adjust the left and right roll gaps. . However, with the conventional method of detecting and controlling meandering based on the difference in rolling load, it is possible to detect and control meandering based on the difference in rolling load that occurs when two pieces of the rolled material are bent due to end bending or when rolling irregularly shaped parts at the leading and trailing ends. It was determined that this was a phenomenon, and the reduction level adjustment was disrupted.
On the contrary, there were fatal defects that caused the rolling operation to be interrupted.

Therefore, in recent years, it has become desirable to control the plate width or meandering of heated metal ingots such as hot-rolled materials and continuously cast materials with high precision, and optical methods are being used as a means of detecting the plate width or meandering, etc. A widthwise position detector has been developed. This device is based on the principle shown in FIG.

That is, the rolled material 1 is illuminated by a light emitter 2 from below the rolled material 1, and the amount of light received in the portion not shielded by the rolled material 1 is measured by the light receiver 3 provided above, that is, in the surface direction of the rolled material 1. This is to detect the board width. The light receiver 3 includes one using a photoelectric element (photodiode), one using a television camera type image pickup tube, etc., and the one using a photoelectric element will be explained below. The principle remains the same even when a television camera type image pickup tube is used. A plurality of photoelectric elements 4 are arranged in a straight line in parallel with the light projector 2 (a "bit" is generally used as a unit of number), and emit an electric signal 6 proportional to the amount of light received from the image focused through the lens 5. By thresholding the amount of received light at a constant level using a predetermined converter, the electrical signal is converted into two types of synchronization signals 7, on and off. Since the focusing distance per 1 bit is determined by the focusing angle 2α (or focusing range L) of the lens 5 and the distance H between the rolled material 1 as the object to be measured and the lens 5, the total number of photoelectric elements is Assuming that W is N bits, the plate width W can be determined by the following formula.

W=L×{N-(N ₁ +N ₂ )}/N = 2H tanα×{N-(N ₁ +N ₂ )}/N
...() Therefore, it is possible to apply such a strip width detection means to detect meandering in rolled materials, etc., and this has already been done in some cases, but especially in hot rolling, when the rolled material itself Since the temperature is around .degree. C., it is effective to eliminate the light projector 2 shown in FIG. 4 and detect the light from the rolled material itself. The principle in this case will be explained with reference to FIG.
are provided, and the light from the rolled material 1 is detected by the light receivers 8 and 9. At the time of detection, the light receiving element 10,
Light is focused for each of the 11 bits, and a voltage proportional to the intensity of the focused light is generated for each bit. For example, if the relationship between the voltage detected by the light receiving element 10 and each bit of the light receiving element 10 is illustrated, the sixth
As shown in the figure, the position where the voltage difference begins to occur is detected as the work side end of the rolled material 1. Note that FIG. 6 is referred to as a video signal. In FIG. 6, ts is a scanning period required to scan all the bits of each of the light receiving elements 10 and 11, and V is a voltage representing the difference in light amount at the width end of the rolled material.

Incidentally, since the temperature generally varies depending on the type of rolled material, a difference occurs in the amount of light entering the light receivers 8 and 9 shown in FIG. 5 depending on the temperature. That is, when the scanning time ts is increased for a hot rolled material, the time for light to enter the light receiving elements 10, 11 becomes longer, and a large amount of weak light emitted from the rolled material and reflected on the roller table etc. is also transmitted to the light receiving elements 10, 11. As a result of the light being received by the rolled material 1, the voltage V increases as shown in FIG.
It rises sharply at a position far from , deteriorating the detection accuracy at the width end. Conversely, if the scanning time ts is too short, the time for light to enter each bit of the light-receiving elements 10, 11 becomes short, and as a result, the light is not sufficiently received by the light-receiving elements 10, 11, as shown in FIG. so that the voltage V
There is a possibility that the level of the plate width end detection signal will not reach the reference threshold voltage _VL , and detection will become impossible. Therefore, the scanning time ts
automatically controls the light receiving elements 10, 11.
It is necessary to maintain the amount of light received at all times constant and to adjust the voltage V as shown in FIG. 7C.

Therefore, the inventor of the present application, for example,
As shown in the specification of No. 77214, when detecting the width end position of a metal lump using a detector composed of a light receiving element group and a lens that receive light emitted from a heated metal lump, the light receiving element is The scanning period is determined from the amount of light received by a light-receiving element near a light-receiving element that generates a voltage at a preset level in the video signal obtained by scanning from the center side toward the width edge, and the detection The light-receiving element of the device is scanned from the center of the metal mass in the width direction at a determined scanning period, and the address of the light-receiving element that generates a voltage at a preset level is determined to accurately position the metal mass in the width direction. We proposed a method and device for detecting this.

[Problems to be Solved by the Invention] However, in the above-described method and device for detecting the position in the width direction of a metal lump, if the field of view of the detector is blocked by a disturbance such as water vapor, water, or oxide scale, There is a problem that the width end position of the metal lump cannot be detected accurately.

The present invention has been made in view of the above-mentioned circumstances, and has an object of making it possible to accurately detect the width end position of a metal lump without being affected by disturbances.

[Means for Solving the Problems] The present invention provides a method for detecting the width end position of a metal lump using a detector consisting of a lens and a group of light receiving elements that receive light emitted from a heated metal lump. The voltage difference between the video signals for each bit obtained by scanning the metal block in the width direction is calculated, the video signal is compared for each bit with a predetermined threshold voltage, and the sign of the difference is determined. The address at the time when the change occurred is memorized, and the voltage difference between the current video signal and the voltage difference between the video signals at one point before is compared and calculated, and the difference in the voltage difference between the video signals at that point within several points is determined. If there is a change in the positive or negative sign of the voltage difference between the video signal and the video signal at one point before, the stored address of the light receiving element is discarded and the voltage difference between the video signal and the video signal at that point changes. If there is no change in the positive or negative sign of the difference in voltage between the video signals one time before, the light receiving element at the time when the video signal voltage became lower than a predetermined threshold voltage. It has a configuration that recognizes the address as the width end position of the metal block.

[Function] Accordingly, in the present invention, the light receiving element is scanned in the width direction of the metal lump, and a comparison calculation is made between the voltage of the video signal and the threshold voltage for each bit.
In addition, the voltage difference of the video signal for each bit is calculated, and if the sign of the difference between the voltage difference of the video signal at the current time and the voltage difference of the video signal at a point before changes in sign, the voltage difference at that point is calculated. The address is not set to the width end position of the metal block, and if there is no change in the positive or negative sign of the voltage difference, the voltage of the video signal at that point is lower than the preset threshold voltage. The address is the width end position of the metal block.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings.

First, the principle of the present invention will be explained with reference to FIGS. 2 and 3. The video signal shown in FIG.
The video signal shown in FIG. 3 is unaffected by disturbances such as water and oxide scale, and the video signal shown in FIG. 3 is affected by disturbances. It was obtained by scanning in the direction at a predetermined scanning period. In addition, the method of scanning and how to adjust the scanning period are explained in the patent application.
Since it is disclosed in the specification of No. 58-238540, the specification of Japanese Patent Application No. 59-77214, etc., the explanation will be omitted.

Now, in Fig. 2, assuming that the video signal is scanned from the center of the rolled material 1 in the width direction, the preset threshold voltage V _L and the voltage at each address are sequentially compared, and it is determined that the voltage at each address is smaller than V _L. The address N _E of the light-receiving element that gives the reduced voltage V _E is determined to be the edge of the plate width.

By the way, as shown in FIG. 3, for example, when a scale 12 is placed on the rolled material 1 and the amount of light entering the light receiving element from that part decreases, the voltage of the video signal of the corresponding light receiving element decreases. In this state, if the width end position of the rolled material 1 is determined by the method explained in FIG. 2, the width end position will be determined as the part on which the scale 12 is placed, resulting in a large error in detection.

In the present invention, in order to prevent this, the voltage difference between the video signal at each address and the one before it, that is, ΔV _i+1 =V _i −V _i+1 , is sequentially determined, and the obtained ΔV _{i+ 1} , and if a sign change occurs, the address that gives a voltage smaller than the threshold in the video signal obtained at that time is discarded. That is, in FIG. 3, i
=k+1, ΔV _k+1 =V _k −V _i+1 >0 is obtained, and since V _k+1 <V _L , address N _k+1 is determined to be the width end position. However, at the next i=k+2 time point, ΔV _k+2 =V _k+1 −V _k+2 <0, and the sign changes from positive to negative. As can be seen from FIG. 3, such a sign change never occurs at the width end position or outside the width end position.
This is because a detector with a group of light-receiving elements is apertured so that the voltage of the video signal decreases near the width end position, and the voltage becomes zero 2 to 3 bits outside the width end position, as shown in Figure 7C. is adjusted appropriately, and the intensity of the reflected light outside the width end position is very weak, ranging from a few tenths to a few hundredths of the intensity of the light emitted by the metal block, so it can be detected. That's because there aren't many.

Therefore, when this sign change is detected and occurs, the address N k ₊₁ that has been obtained so far where V _k+1 <V _L is discarded. By doing this,
The address corresponding to the width end position of the rolled material on the light receiving element can be determined with high precision without being affected by disturbances such as scale. Although FIGS. 2 and 3 show the case where the scanning direction is scanned from the center of the rolled material 1 toward the width end, the same applies to the case where the scanning direction is scanned from the width end toward the center. In this case, the sign of the voltage difference changes from negative to positive, and the address at which the voltage difference first becomes larger than the threshold voltage V _L is the width end position. Therefore, regardless of which direction scanning is performed, it is sufficient to compare the video signal and the threshold voltage and find the address of the video signal at the time when a sign change occurs.

Next, with reference to FIG. 1, a specific example of the present invention will be described regarding scanning from the center side to the width end direction.

In the figure, A is a video signal obtained by scanning the photoelectric element of the detector in the width direction of the rolled material as disclosed in the above-mentioned specification, and 13 is the image signal of the address currently being scanned for each pulse of the clock pulse C. A comparator 15 is a comparator that compares and calculates the voltage V _i+1 of the video signal obtained by the light receiving element and the voltage V _i of the video signal obtained by the light receiving element at the first address sent from the shift register 14. The voltage difference ΔV _i+1 =V _i+1 −V _i sent from the comparator 13 and the voltage difference ΔV _i =V _i −V _i-1 at the previous point sent from the shift register 16. 17 is a sign determination circuit that determines the sign of the calculation result of the comparator 15. 18 is a comparator that compares the voltage V _i+1 of the video signal A and the threshold voltage V _L. 19 stores the address of the video signal that gives a voltage smaller than the threshold voltage V _L compared by the comparator 18, and the sign discriminator circuit 1
A memory circuit 20 discards the stored address when the clear pulse CE from 7 is input, and a counter 20 counts the number of clock pulses C and sends the number to the memory circuit 19 as an address.

When detecting the width end position of the rolled material, the voltage V _i+1 of the video signal A of the rolled material and the voltage V of the video signal before the address 1 stored in the shift register 14 are detected by the comparator every pulse of the clock pulse C. 13, the difference between them is compared and calculated as ΔV _i+1 =V _i −V _i+1 , and the voltage difference ΔV _i+1 is sent from comparator 13 to comparator 1
5 and the shift register 16. Further, in the shift register 14, the value of the video signal A is updated every pulse of the clock pulse C.

The voltage difference ΔV _i+1 output from the comparator 13 is compared in the comparator 13 with the voltage difference ΔV _i at a point before stored in the shift register 16 and ΔV _i −ΔV _i+1 , and the signal is is output to the sign discriminator 17, and the sign discriminator 17 discriminates whether the output from the comparator 15 is positive or negative.

On the other hand, the voltage V _i+1 of the video signal A is constantly compared with the threshold voltage V _L by the comparator 18 and sent to the _storage circuit ₁₉ .
>V _k+1 , so the value at address N _k remains in the storage circuit 19 at this time. Therefore, if this continues, the N _k address will be recognized as the width end of the rolled material, but
When the output of the comparator 15 becomes negative, a clear pulse CE is sent to the storage circuit 19 from the sign discrimination circuit 17.
address _Nk is rejected. Through this operation, the address N _E of the light receiving element representing the true width position of the rolled material 1 remains in the memory circuit 19. In the shift register 16, the value of the voltage difference is updated every pulse of the clock pulse C.

As described above, even if the field of view of the detector is partially blocked by steam, water, etc., or even if water, oxide scale, etc. remain on the rolled material, the width end portion of the rolled material can be accurately determined.

In the embodiments of the present invention, a case has been described in which the position of the width end of a rolled material is detected, but the present invention is applicable not only to rolled materials but also to any high-temperature metal lump. It goes without saying that it can be constructed by a computer or by hardware such as an electronic circuit, and that various changes can be made without departing from the gist of the present invention.

[Effects of the Invention] According to the method and device for detecting the position in the width direction of a metal lump of the present invention, moisture, water, oxide scale, etc. can be detected when measuring the end position of a heated metal lump with an optical detector. This has the excellent effect of eliminating the influence of unavoidable disturbances and enabling highly accurate measurements.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an example embodying the method and device for detecting the position in the width direction of a metal lump according to the present invention, and FIGS. An explanatory diagram of the principle, Fig. 4 is an explanatory diagram of the principle of detecting the widthwise position of a material such as a metal lump, Fig. 5 is an explanatory diagram of the principle of detecting the widthwise position of a heated metal lump, Fig. 6 5 is a graph showing the relationship between the signal representing the difference in light amount occurring at the width edge and the scanning time in the case of width direction position detection, and FIG. FIG. 3 is an explanatory diagram showing changes in output signals due to changes in scanning time. In the figure, 13 is a comparator, 14 is a shift register, 1
5 is a comparator, 16 is a shift register, 17 is a sign discrimination circuit, 18 is a comparator, 19 is a storage circuit, 20
indicates a counter.

Claims (1)

[Claims] 1. When detecting the width end position of a metal lump using a detector consisting of a group of light receiving elements and a lens that receive light emitted from a heated metal lump, the light receiving element is moved in the width direction of the metal lump. The video signal voltage for each bit obtained by scanning is compared with a predetermined threshold voltage, and the address of the video signal at the time when a sign change occurs is recorded. A position in the width direction of a metal block, characterized in that the voltage difference between the current video signal and the video signal one time before is calculated, and if a sign change occurs in the voltage difference, the stored address is discarded. Detection method. 2. A detector capable of scanning the metal lump in the width direction, consisting of a light receiving element group and a lens that receive light emitted from the heated metal lump, and a video signal of the detected predetermined location and an image of the nearest location. A comparator that compares and calculates the voltage difference between signals, a comparator that compares and calculates the voltage difference between the current video signal sent from the comparator and the voltage difference between the video signal at a point before, and the current video signal. A sign discrimination circuit that determines the positive or negative sign of the voltage difference between the voltage difference between the voltage difference of A comparator that compares and calculates the difference with the threshold voltage, and when a sign change occurs in the output of the comparator, the address of the light receiving element at that time is memorized and a clear pulse is sent from the sign discrimination circuit. A device for detecting a position in the width direction of a metal lump, further comprising a memory circuit for discarding the stored address of the light-receiving element.