RU2245514C2 - Method for laser control of rolled strip shape - Google Patents

Abstract

FIELD: laser control technologies.

SUBSTANCE: method includes sweep of light beam to straight line with providing for projection of this beam on surface of rolled strip, video capture of projection area of current beam on portion of controlled surface and point of nearby edge of rolled strip, projection area is separated on given number of ranges and for each range received image is separated on components, forming respectively line of edge points of beam light projection, being portion of measurement area, line of brightest points inside light beam projection range and line of edge points of beam projection, quitting measurement area, to determine their coordinates along rolling strip surface, coordinates of lines of brightest points and edge points within light beam projection are straightened, and value of total coordinate is determined, from which with consideration of coordinates of points of lines of brightest points within light beam projection, by geometric interpretation, total parameter of rolled strip shape SARK_(i,j) is determined.

EFFECT: higher trustworthiness and efficiency.

8 dwg

Description

The invention relates to measuring technique and relates to a method for controlling the shape of the rolled strip.

The main controlled parameters during rolling of metal strips are the thickness, its transverse and longitudinal thickness thicknesses, characterized by the profile of the strips, as well as the shape and flatness (flatness) of the strips. Due to the fact that in the rolling industry there is no single certainty in the application of the terms of profile, shape and flatness, and in various literary and patent publications you can find different interpretations of their application, brief definitions of the terms used are given below (for the purpose of unambiguous semantic understanding).

The strip profile is a measure of the lateral change in thickness. The main technological parameters that affect the profile are the thermal and mechanical barrel, as well as the elastic flattening of the work rolls.

The shape of the strip characterizes the lateral change in elongation across the width of the rolled strip. A transverse change in elongation occurs when the percent reduction in width changes and the corresponding advance in width is not equal. The main reason leading to this is an inappropriate incoming strip profile, along with the same parameters that affect the profile. The shape of the strip is evaluated when rolling on a rolling mill. Rolling is carried out under tension created by additional external load.

The shape of the rolled strip can be controlled by thermal (differentiated supply of cutting fluid along the length of the work rolls), power (additional bending or anti-bending of the work rolls), or by joint profiling of the rolls. The flatness of the strip is its ability to lie on a flat ideal surface without the use of additional external load. To assess the flatness, it is possible to use threshold values of the external load. She is evaluated at the stand after rolling.

Flatness is associated with the shape in such a way that any transverse change in pressure can lead to the formation of defects (waves) in the strip if the tension applied during rolling is removed, for example, on a measuring stand after rolling or removing, and reducing the tension on the mill. When the profile changes, the shape and, accordingly, flatness change. And vice versa, a change in shape can lead to a change in profile.

Thus, during the rolling process, the shape of the rolled strips is controlled, by measuring which the process is adjusted and the flatness of the finished strips is evaluated. At the same time, the shape of the strips is of industrial importance as an important parameter that affects not only the final product, but primarily the productivity of the equipment. An inappropriate form reduces the rolling speed, and when critical values are reached, the process is destabilized, up to a stop, due to breaks, etc.

There is a method of optical control of the shape of the rolled strip, which consists in scanning the surface of the rolled strip in the transverse direction with a light beam, determining the given parameters of individual points of the given beam on the specified surface and comparing these parameters with the reference ones (RU No. 2179328, G 02 B 21/00, publ. 10.02.2002).

The known method consists in the fact that the reference surface is pre-scanned with a light beam, and then the test surface is scanned along the same paths, with each point of both the test and reference surfaces being sequentially scanned by at least the first and second light beams, said light beams are divided into two paraxial rays, one of which is shifted relative to the others in frequency and space along the first axis in the first light beam and along the second axis orthogonal to it in the second a light beam, while measuring the phase difference of the reflected rays for a selected number of points of the scanned surface, approximating the data on the phase difference of the reflected rays obtained by scanning the reference surface, two-dimensional polynomials, then carry out two-dimensional integration of these approximated data along the paths of the light beams and approximate these integrated data by two-dimensional polynomials, then correct the data on the phase difference of the reflected rays obtained by scanning According to the approximated data on the phase difference of the reflected rays at the corresponding points of the reference surface, two-dimensional integration of the corrected data obtained by scanning the investigated surface along the paths of the light beams is carried out, and these integrated data are corrected based on the mentioned approximated and integrated data the phase difference of the reflected rays at the corresponding points of the reference surface, according after which they build an image and / or determine the profile parameters of the investigated surface.

The disadvantages of this method are its hardware complexity and complexity in the algorithmic solution, which does not allow to obtain the final indicators in express mode, which could be used as correction parameters and control parameters of the technological process of rolling the strip, which is controlled in the current time.

The present invention is aimed at expanding the arsenal of hardware that allows for a new algorithm to control the shape of the rolled strip with the simultaneous generation of control signals for the rolling process of this strip.

The technical result achieved in this case is to increase the reliability and time efficiency of the method for controlling the shape of the rolled strip, allowing the use of the control results as control signals for the rolling process of this strip.

The specified technical result is achieved in that in the method of laser control of the shape of the rolled strip, which consists in scanning the surface of the rolled strip in the transverse direction with a laser beam, determining the specified parameters of individual points of the beam on the specified surface and comparing these parameters with the reference ones, characterized in that when scanning ensure the projection of the laser beam on the surface of the rolled strip, carry out video capture of the projection of this beam on the surface of the rolled strip the points of the adjacent edge of the rolled strip, then the resulting video image of the projection of the laser beam is divided into a predetermined number of intervals along the width of the rental and for each interval the resulting video image is decomposed into a line of the most extreme points of the projection of the beam included in the projection, the line of the brightest points inside the projection of the beam, the line the most extreme points of the projection of the beam, leaving the measurement zone, and make the coordinates of the component lines, and then, using the taken coordinates, calculate the generalizing parameter SARK, evaluating the shape (flatness) of the rental according to the formula

Sy _i = Y _pi × Yno _i = ly;

Sx _i = ((Yno _i + Xno _i ) / 2) × (Xp _i -Yp _i ) = Ix;

S = Sx _i + Sy _i = I;

SARK _{(i, j)} = I $\genfrac{}{}{0ex}{}{\text{1 / z}}{\text{(i, j)}}$ or (log _{i (i, j)} SARK _{(i, j)} ) × z _{(i, j)} = 1,

where Yp _i is the coordinate of the line of the brightest points within the range of projection of the light beam at the i-th point along the width of the rental;

Xp _i - the coordinate of the line of the most extreme points of the light projection of the beam, leaving the measurement zone, at the i-th point along the width of the rental;

Yno _i - normalized coordinate of the line of the brightest points within the range of projection of the light beam at the i-th point along the width of the rental;

Xno _i is the normalized coordinate of the line of the most extreme points of the light projection of the beam emerging from the measurement zone at the i-th point along the width of the rental;

Z (ij) is the value summing the coordinates of Yno _i and Xno _i .

These features are significant and interconnected with the formation of a stable set of essential features sufficient to obtain the desired technical result.

The present invention is illustrated by a specific example, which, however, is not the only possible, but clearly demonstrates the possibility of obtaining the desired technical result.

Figure 1 - diagram of the scanning system with respect to the rolled strip, top view;

figure 2 is the same as in figure 1, side view;

figure 3 - diagram of the decomposition of the video into component lines;

figure 4 - illustration of the calculation of the summing coordinates Zn _i ;

5 is an illustration of a geometric interpretation;

6 is a graph comparing the speed of a Wi signal with a reference value (first example of a reference);

Fig.7 is the same as in Fig.6, a second example of a standard;

Fig.8 is the same as in Fig.6, a third example of a standard;

According to the present invention, the method of laser control of the shape of the rolled strip consists in scanning the surface of the rolled strip in the transverse direction with a light beam, determining the given parameters of individual points of the given beam on the specified surface, and comparing these parameters with the reference ones. When scanning, the light beam is scanned in a straight line with the projection of this beam on the surface of the rolled strip, then the video captures the projection zone of this beam on the area of the controlled surface and the point of the adjacent edge of the rolled strip, breaks the light beam measurement zone into a predetermined number of intervals and for each interval the resulting video image is decomposed into constituent points, respectively forming a line of the most extreme points of the light projection of the beam included in measurement, the line of the brightest points inside the projection area of the light beam and the line of the most extreme points of the light projection of the beam leaving the measurement zone, to determine their coordinates along the length of the rental surface, normalize the coordinates of the lines of the brightest points inside the measurement zone and the most extreme points of the light projection of the beam leaving the measurement zone, and determine the value of the summing coordinate, which is the resulting speed of the normalized optical coordinates, according to which, taking into account the coordinates of the points of the lines of the most bright points inside the measurement zone and the most extreme points of the light projection of the beam emerging from the measurement zone, by means of geometric interpretation determine the generalizing shape parameter of the rolled strip SARK _{(i, j)} according to the following formula:

Sy _i = Y _pi × Yno _i = ly;

Sx _i = ((Yno _i + Xno _i ) / 2) × (Xp _i -Yp _i ) = Ix;

S = Sx _i + Sy _i = I;

SARK _{i, j)} = I $\genfrac{}{}{0ex}{}{\text{1 / z}}{\text{(i, j)}}$ or (log _{i (i, j)} sark _{(i, j)} ) × z _{(i, j)} = 1,

where Yp _i is the coordinate of the line of the brightest points within the range of projection of the light beam at the i-th point along the width of the rental;

Xp _i - the coordinate of the line of the most extreme points of the light projection of the beam, leaving the measurement zone, at the i-th point along the width of the rental;

Yno _i - normalized coordinate of the line of the brightest points within the range of projection of the light beam at the i-th point along the width of the rental;

Xno _i is the normalized coordinate of the line of the most extreme points of the light projection of the beam emerging from the measurement zone at the i-th point along the width of the rental;

Z (i, j) is the value summing the coordinates of Yno _i and Xno _i .

The following is a discussion of a specific example implementation of the method of the present invention.

The proposed method is as follows.

To implement the method, the scanning system shown in Figs. 1 and 2 is used. The source of laser radiation 1 is an optical scan of the beam in a straight line 2, which is projected onto the surface of the rolled (controlled) metal 3.

The receiving system 4 captures the projected area of the laser beam 5 on a controlled surface and point 6 of the adjacent edge of the rolled strip. A GN15, GN25 helium-neon laser is used as a laser radiation source with a built-in mirror lens that scans the laser beam in a straight line, and the scan thickness is adjustable in the range from 4 to 12 mm depending on the requirements of rolling and measuring conditions, such as high-speed mode works, background illumination, etc. As a receiving system, any video capture system is used that allows video surveillance of the range of the controlled band in real time with a frequency of 25-50 n, the transfer of information in the computing processing unit (not shown). As a computing technique, a personal computer is used, equipped with a block for receiving and digitizing the image with the corresponding software, which processes the data in accordance with a given algorithm.

The resulting video image of the projection of the laser beam is decomposed into the following component lines (figure 3):

- “O” - the line of the most extreme points of the laser projection of the beam entering the measurement zone;

- “Y” - the line of the brightest points inside the measurement zone;

- “X” is the line of the most extreme points of the laser projection of the beam emerging from the measurement zone.

Then, the projection area of the laser beam is divided into i intervals along the rolled width. Moreover, the number of breakdown intervals in width can be from 0 to 600 or more, depending on the installation angles of the scanning system and the characteristics of the receiving system.

The coordinates of the laser line projections are taken:

- Yo _{(i, j)} - coordinate of the “Y” line at the i-th point along the width of the rental and at the corresponding j-th point along the length of the rental;

- Xo _{(i, j)} - the coordinate of the line “X” at the i-th point along the width of the rental and at the corresponding j-th point along the length of the rental;

- Yp _{(i, j)} - coordinate of the “Y” line at the i-th point along the width of the rental and at the corresponding j-th point along the length of the rental (origin in T.O);

- Хр ( _{i, j)} - coordinate of the “X” line at the i-th point along the rental width and at the corresponding j-th point along the rental length (origin in t.O);

- Yh _(j) is the coordinate of the edge (Fig. 1, 2, item 6) along the length of the rolled product at the j-th point, which characterizes the change in thickness (longitudinal profile).

Evaluation of values for each of the divided intervals i is carried out according to the maximum value inside the i-th interval, the arithmetic mean value inside the measured interval, and the standard deviation inside the measured interval.

Normalization optical values and YO Ho _{i i} by the formula

Xn _i = (Xo _i -Xo ^min ) / Xo ^min ,

Yn _i = (Yo _i -Yo ^min ) / Yo ^min ,

where Хо ^min and Yo ^min - the minimum value of the corresponding coordinates over the entire width of the rolled metal.

The calculation of the values of the summing coordinates Zn _i (figure 4), the physical meaning of which reflects the resulting speed of the horizontal Xn _i and vertical Yn _i component, is carried out according to the formula

Zn _i = (Xn $\genfrac{}{}{0ex}{}{\text{2}}{\text{i}}$ + Yn $\genfrac{}{}{0ex}{}{\text{2}}{\text{i}}$ ) ^0.5 .

Next, a geometric interpretation (Fig. 5) and calculation of the generalizing parameter SARK (i, j), evaluating the shape (flatness) of the rental:

Sy _i = Yp _i × YnO _i = ly;

Sx _i = ((Yno _i + Xno _i ) / 2) × (Xp _i -Yp _i ) = Ix;

S = Sx _i + Sy _i = I;

SARK _{(i, j)} = l $\genfrac{}{}{0ex}{}{\text{1 / z}}{\text{(i, j)}}$ or (log _{i (i, j)} SARK _{(i, j)} ) × Z _{(i, j)} = 1.

SARK _{(i, j)} and Yh _j indicators are a system that characterizes the profile, shape and flatness of rolled products, which allow us to visualize the form and are the initial data for the correct control of the technological process. They can also be used as source (input) data in automated regulation and control systems.

However, the proposed method allows to evaluate the surface quality of the rolled material and the defects of the controlled surface. This is feasible when the area of controlled rolling width is divided into the maximum number of areas (m > 200).

The SARK parameter is used to correctly control the process by adjusting the shape of the rental. Using the method of detecting moving objects, spatio-temporal filtering of the SARK parameter is performed according to the algorithm:

- determination of the absolute values of Li Laplacians by the formula

Li (SARK) = SARKi _{i, (j + 1)} -2 × SARK _{i, (j)} + SARK _{i, (j-1)} ,

where (j + i), (j), (j-i) are three consecutive points in time at the i-th point along the width of the rolled strip;

- determining the speed of movement of the image of the Wi signal by dividing the threshold values of the Laplacians that underwent space-time filtering by the time interval during which the shift

Wj = l _{(i, j)} (SARK) / τ;

τ = 3 / Vskan,

where τ is the time during which the three measured values changed:

(j + i, j and j-1): l _i (SARK).

After that, the Wi values are binarized by setting the thresholds of the obtained values. Values less than a given threshold Q are assigned a binarized level “O”, values equal to and greater than a given threshold Q are assigned a binarized level “1”.

Next, the obtained values of the speed of movement of the Wi signal at the i-th point along the rolling width are converted into the longitudinal axis j, and comparison is made with one of the proposed three standards (Fig.6, 7, 8).

Correct process control by comparison with the developed standards is carried out by identifying the actual value of Wi at the binarized level with the corresponding standard, deciding on the use of one or another standard and regulation method (feedback). Operational feedback can be carried out by purely thermal, power or joint profiling of the rolls.

Purely thermal profiling is carried out in the case of a random arrangement of certain standards across the width of the rolled strip. In the identification section with the first reference (Fig. 6) (shortening the strip at the i-th point), the supply of cutting fluid cutting fluid is reduced from 50% (nominal) to 25% in the nozzle corresponding to the width of the rolled strip, thereby local an increase in the diameter of the work roll and elongation of the strip at this point (thermal profiling of the rolls). The nozzle operating mode returns to its original (nominal value - 50%) when identifying the actual Wi value to the third standard (Fig. 8) (ideal or acceptable value at the binarized level). In the identification area with the second standard (Fig. 7) (strip elongation at the i-th point), the supply of cutting fluid cutting fluid is increased from 50% (nominal) to 75% in the nozzle corresponding to the width of the rolled strip, thereby local reducing the diameter of the work roll and shortening the strip at this point (thermal profiling of the rolls). The nozzle operating mode returns to its original (nominal value - 50%) when identifying the actual Wi value to the third standard (Fig. 8) (ideal or acceptable value at the binarized level). As follows from the above, in the area of identification of the actual value of Wi with the third standard (ideal or acceptable value at the binarized level), the nozzle supplies the cutting fluid at the nominal level (for example, 50%, depending on the rolling conditions, the nominal level and the level of correction can be adjusted initial setting of the process).

Power roll profiling is performed in the following cases. The width of the rolled strip is conventionally divided into three equal segments (left, middle and right side), and with the appropriate location of the standard in the considered zone in 50% or more cases or with a sequential arrangement of 30% or more in the transverse direction, force profiling is applied: additional bending (first standard) or anti-bending of work rolls (second standard).

If it is impossible to eliminate the defects in the shape and reach the specified shape (third standard) within 7-15 seconds, a joint thermal and power profiling is performed, and the priority control channel in this case is power profiling, and then joint.

According to the recorded values of the form and its adjustment to a file or other source of archival information, the proposed method also allows for the initial adjustment of the rolling mill: mechanical profiling and roughness of the rolls, the composition of the technological lubricant, additives added to it, etc.

Claims (1)

The method of laser control of the shape of the rolled strip, which consists in scanning the surface of the rolled strip in the transverse direction with a laser beam, determining the specified parameters of individual points of the given beam on the specified surface and comparing these parameters with the reference ones, characterized in that during scanning they provide a projection of the laser beam on the surface of the rolled stripes, carry out video capture of the projection of this beam on the surface of the rolled strip and the point of the nearby edge of the rolled strip, d Next, the resulting video image of the projection of the laser beam is divided into a specified number of intervals along the rental width and for each interval the resulting video image is decomposed into the line of the most extreme points of the projection of the beam included in the projection, the line of the brightest points inside the projection of the beam, the line of the most extreme points of the projection of the beam emerging from measurement zone, and make the coordinates of the component lines and then, using the taken coordinates, calculate the generalizing parameter SARK, evaluating the shape (flatness) of the rental.

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