Tension setting method applying cross slope

Abstract

The invention relates to a tension setting method applying a cross slope, which is characterized by comprising the following steps of: 1, carrying out range subdivision on the thickness and the width of strip steel according to a product outline; 2, querying four point values of a region boundary in two dimensions; and 3, setting a unit tension value by using a cross slope. According to the scheme, fluctuation of strip steel tension is reduced, the product quality is improved, and field production is more stable and smoother.

Description

TECHNICAL FIELD

[0001] The application relates to a tension setting method using cross slope, and belongs to the field of automatic control of continuous annealing unit. BACKGROUND

[0002] For a continuous annealing unit, the most important control of the production line is stable tension control. A slight deviation can easily cause a series of problems such as slipping, ribbing and deviation of the strip. The thinner the specification is, the more accurate the tension value is required, so the tension value of each specification needs to be accurately calculated. In the current process control system, the calculation of the tension setting value adopts a fixed table lookup method. According to the thickness of the unit that can be produced, the thickness level is divided, according to the width, the width level is divided, and then combined with the steel type. The experience data of the unit tension of each specification and each steel type is stored in a table. The thickness of the strip is in the range of the level, the width is in the range of the level, the actual value is closer to which level, and the unit tension of which level is taken, and then multiplied by the surface area of the strip, so as to calculate the total tension of the strip. The L2 system issues the total tension to L1 for tension control of the production line. This table lookup calculation method has a limited number of thickness points and width points. Unless it falls exactly on the intersection point of the thickness and width, the value of the fixed point obtained by lookup is either too low or too high, which is very unfavorable for accurate control of the tension of the strip and has a great impact on stable production.

[0003] After the novelty search, the invention patent "Artificial intelligence automatic control method for annealing furnace tension" (ZL202110483149.X) applies a roll tension model, covers the length change of the strip due to factors such as temperature and ductility, and takes the line speed of the furnace roller as the control quantity to calculate the stress suffered by the strip between the furnace rollers. The isochoric tension model is applied to control the isochoric change of the tension in the furnace. The change of the tension in the furnace is calculated. The PLC logic of the annealing furnace tension control is optimized by combining the genetic algorithm. Through the data processing of the PLC, the tension in the furnace is calculated and participates in the control of the annealing furnace tension. The invention patent "Cold continuous rolling tension dynamic setting method for stable rolling" (ZL201610785176.1) provides a cold continuous rolling tension dynamic setting method for stable rolling. By dynamically setting the tension in different speed intervals, the smooth transition of the rolling force in different speed intervals is ensured, the risk of strip breakage caused by excessive increase of the rolling force at low speed is reduced, and stable production of the rolling mill is ensured. The present application is completely different from the similar patents. SUMMARY

[0004] The present application is just for the problems existing in the prior art, the setting of tension is optimized, the original rough control of fixed tension value in an interval range is abandoned, the concept of "cross slope" is introduced, the tension control is refined, that is, the dimension of calculation is divided into three dimensions: width, thickness and tension, the value of tension is calculated on the width and tension plane according to the slope, then the value of tension is calculated on the thickness and tension plane, and finally the tangent value of the two planes is taken as the final total tension. The method no longer uses the previous fixed point position to move up or down, but uses independent setting for each coil of strip steel, so that the tension control is more fine, especially when the specification is transitioned, it is more smooth, the fluctuation of the tension of the strip steel is reduced, the product quality is improved, and the on-site production is more stable and smooth.

[0005] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows: a tension setting method using cross slope, the method comprising the following steps:

[0006] Step 1: according to the product outline, the thickness and width of the strip steel are subdivided in range;

[0007] Step 2: query the four point values of the region boundary in two dimensions;

[0008] Step 3: use "cross slope" to realize the setting of unit tension value.

[0009] In the step 1, according to the product outline, the thickness and width of the strip steel are subdivided in range, which is as follows:

[0010] The width and thickness range of the strip steel is not fixed, the original division degree of the unit is determined by the process personnel on site through a large number of experiments, and is optimized many times according to the actual situation in the later production practice according to the product outline of the unit. At present, the thickness range matched with the production capacity of the unit is 0.17-0.55mm, and the width range is 700-1080mm, wherein the thickness is divided into 14 levels, which are 170, 180, 190, 200, 220, 250, 280, 300, 350, 400, 450, 500, 550 and 600, and the width is divided into 5 levels, which are 700, 800, 900, 1000 and 1080

[0011] Step 2: query the four point values of the region boundary in two dimensions;

[0012] The first dimension: strip thickness. The query of the boundary values of the area can be achieved through a data cursor. Based on the previous step, we define the total number of thickness levels TenThkCnt, and then place the cursor at the lowest position. Each time the cursor is moved, a thickness value of TenThk is stored in the thickness array TenThk[i] until all 14 thicknesses in TenThkCnt are stored in the corresponding array.

[0013] The second dimension: strip width. The method is the same as above. Define the total number of width levels TenWidCnt, then place the cursor at the lowest position. Each time the cursor is moved, a width value of TenWid is stored in the width array TenWid[i] until all 5 widths in TenWidCnt are stored in the corresponding array.

[0014] When a new coil arrives at the uncoiler position, the primary automation system will issue a production data request. After receiving the request, the secondary process control system obtains the original information of the current coil based on the tracking position and organizes the corresponding production data. When organizing the tension values of each area segment, first complete the upper and lower thresholds of the thickness in the first dimension. According to the strip thickness coil_thick, judge from low to high in sequence. If coil_thick > TenThk[i], then i is incremented by 1, and the cursor advances one position upward until coil_thick < TenWid[i]. At this time, the two area boundary values of the thickness are obtained as TenThk[i - 1] and TenThk[i]; similarly, the two area boundary values of the width in the second dimension are TenWid[i - 1] and TenWid[i].

[0015] Here is an explanation. If the original value exactly falls on the grade boundary, such as coil_thick = TenThk[i], then both area boundary values are TenThk[i]; if the original value is lower (or higher) than the lowest (or highest) limit of the cursor, then both area boundary values are TenThk[1] (or TenThk[max]).

[0016] Step 3: Use the "cross slope" to set the unit tension value;

[0017] Establish a rectangular coordinate system as shown in the following figure according to the strip thickness grade and width grade. Let the strip thickness be x, the width be y, and the unit tension of the strip be f(x, y). Let the lower limit value of the thickness range where the strip is located be x1, the upper limit value be x2, the lower limit value of the width range where the strip is located be y1, and the upper limit value be y2:

[0018] According to the distribution positions of the strip thickness and width, it can be divided into the following four cases:

[0019] If the thickness and width values ​​of the strip steel fall exactly at the intersection of the thickness grade and width grade boundary values, then the value at that intersection is the unit tension of the strip steel. This value does not require slope correction and can be directly obtained from a table.

[0020] Ifx=x1,y=y1thenf(x,y)=f1

[0021] f(x, y) = f3

[0022] If x = x1, y = y2 then

[0023] Ifx=x2,y=y1thenf(x,y)=f2

[0024] Ifx=x2,y=y2thenf(x,y)=f4

[0025] If the strip thickness falls exactly on the boundary value of the thickness grade, for example, x = x1, then a single slope is used for fine adjustment of the tension value:

[0026]

[0027] Similarly, if the strip width value falls exactly on the boundary value of the width grade, for example, y = y1, then

[0028]

[0029] Since the thickness and width of the strip lie at the right angle points of the region and are not on the boundary lines of the region, the point of tangency needs to be determined using the plane intersection slope:

[0030]

[0031]

[0032] make

[0033]

[0034] Then, the product of the coefficients at the tangency point and the unit tension is used to achieve joint correction:

[0035] f(x,y)=f1(x,y)+(f2(x,y)-f1(x,y))coey

[0036] =f1+(f2-f1)coex+(f3+(f4-f3)coex-f1-(f2-f1)coex)coey

[0037] =f1+(f2-f1)coex+(f3-f1)coey+(f4+f1-f2-f3)coex*coey

[0038] Finally, the total tension is obtained by multiplying the unit tension by the surface area.

[0039] Compared with existing technologies, the advantages of this invention are as follows: It develops a method for accurately calculating the tension of non-boundary value products. By using two planar slope calculations in three-dimensional space, the slope factors on the thickness and width are obtained from the first calculation. The slope factors are then imported into the second tension calculation to obtain a definite tension value. When the strip tension specifications change, the tension curve value is smooth, which makes up for the shortcomings of the past method of obtaining only boundary tension by looking up a fixed table. This reduces tension fluctuations, which is more conducive to improving product quality and stabilizing production. Attached Figure Description

[0040] Figure 1 The present invention relates to a cross-slope tension diagram of two surfaces;

[0041] Figure 2 A comparison diagram of the tension after the implementation of this invention and the original tension.

[0042] Implementation

[0043] To enhance understanding of the present invention, the embodiments will be described in detail below with reference to the accompanying drawings.

[0044] Table 1 is a unit tension storage table that is subdivided according to thickness grade and width grade according to the present invention. This table is stored in the process control system as a constant table and is the base table for tension control. It can be further subdivided according to the production control situation. The unit tension value can be fine-tuned by the process personnel to better meet the actual needs of on-site control. This table includes the critical unit tension values ​​of various specifications of the uncoiler, cleaning section, inlet looper, outlet No. 1 looper, outlet No. 2 looper and coiling machine.

[0045]

[0046]

[0047] Figure 1 This invention relates to a two-plane intersection planar diagram, in which f1, f2, f3, and f4 are the unit tensions at four critical positions, f1(x, y) is the adjusted unit tension in the thickness dimension, f2(x, y) is the adjusted unit tension in the width dimension, and f(x, y) is the adjusted unit tension in the intersection slope.

[0048] Figure 2It is a comparison chart of the tension after the implementation of the present invention and the original tension. Assuming that the width remains unchanged and the thickness gradually increases, it can be seen from this chart that there is an obvious jump in the original tension, while the optimized tension has better smoothness and more fluent control.

[0049] The present invention has been applied to the tension control of the 1420 cold rolling continuous annealing unit in Meigang. It can also be applied to production lines with similar requirements and other control units, such as rolling force, elongation, etc. Specific embodiments

[0050] For the tension control (except the furnace section) of the 1420 cold rolling continuous annealing unit in Meigang, the control system issues commands to the PLC, and then the PLC issues commands to each field device for execution. The execution process of the control system is as follows:

[0051] Example: The incoming material thickness coil_thick is 0.23 cm, and the width coil_width is 925 cm

[0052] Step 1: Obtain the range breakdown table of the strip thickness and strip width;

[0053] See Table 2:

[0054] Set point 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Thickness 170 180 190 200 220 250 280 300 350 400 450 500 550 600 Width 700 800 900 1000 1080

[0055] And store the thickness of the above values into the thickness array TenThk[], and the width into the width array TenWid[].

[0056] Step 2: Query the four point values of the regional boundary in two dimensions;

[0057] Thickness dimension: The total number of thickness levels TenThkCnt = 14, the cursor is placed at the lowest position. At this time, the thickness array TenThk[0] = 170. Determine whether the incoming material thickness coil_thick is less than TenThk[0]. The result is no, so the cursor moves one position, TenThk[1] = 180. At this time, the condition is still not met. By analogy, until TenThk[5] = 250. At this time, coil_thick < TenThk[5] is satisfied. Thus, the two boundary values in the thickness dimension are obtained as TenThk[4] = 220 and TenThk[5] = 250.

[0058] Width dimension: The total number of width levels TenWidCnt = 5, the cursor is placed at the lowest position. At this time, the width array TenWid[0] = 700. It is judged whether the incoming material width coil_width is less than TenWid[0]. The result is no, so the cursor is moved one position, TenWid[1] = 800. At this time, the condition is still not met. And so on until TenWid[3] = 1000. At this time, coil_width < TenWid[3] is satisfied. Thus, the two boundary values in the width dimension are obtained as TenWid[2] = 900 and TenWid[3] = 1000.

[0059] Step 3: Use the "cross slope" to set the unit tension value;

[0060] For a clearer description, we split Step 3 into four sub-steps and explain them step by step.

[0061] (1) First, obtain the four unit tensions at the boundary points.

[0062] As shown in Table 3 below:

[0063]

[0064] The unit tensions of the uncoiler POR are circled in the above table. At this time, f1 = 24.9, f2 = 23.02, f3 = 23.46, f4 = 21.76.

[0065] (2) Calculate the tension adjustment slope factors in the two dimensions.

[0066] Coex = (coil_thick - TenThk[4]) / (TenThk[5] - TenThk[4])

[0067] = (230 - 220) / (250 - 220)

[0068] ≈0.333

[0069] Coey = (coil_width - TenWid[2]) / (TenWid[3] - TenWid[2])

[0070] = (925 - 900) / (1000 - 900)

[0071] ≈0.25

[0072] (3) Calculate the unit tension during the production of this steel coil.

[0073] f(x, y) = f1(x, y) + (f2(x, y) - f1(x, y))coey ​=f1+(f2-f1)coex+(f3-f1)coey+(f4+f1-f2-f3)coex*coey

[0075] =24.9 + (23.02 - 24.9) * 0.333 + (23.46 - 24.9) * 0.25 +

[0076] (21.76+24.9-23.02-23.46)*0.333*0.25

[0077] =23.928

[0078] (4) The total tension of the steel coil is finally obtained.

[0079] F(total) = f(x, y) * mlf

[0080] =23.928*0.23*925

[0081] ≈5091

[0082] The above is an example of illustrative instructions using the tension of the uncoiler as an example. The tension control values ​​for other areas can be found in Table 4 below:

[0083] Table 4:

[0084]

[0085] It should be noted that the above embodiments are not intended to limit the scope of protection of the present invention. Equivalent transformations or substitutions made based on the above technical solutions all fall within the scope of protection of the claims of the present invention.

Claims

1. A tension setting method using cross slope, characterized in that, The method includes the following steps: Step 1: Subdivide the ranges of strip thickness and strip width according to the product outline; Step 2: Query the four point values of the regional boundaries in two dimensions; Step 3: Use the "cross slope" to set the unit tension value.

2. The tension setting method using cross slope according to claim 1, characterized in that, The said Step 1: Subdivide the ranges of strip thickness and strip width according to the product outline, specifically as follows: For the subdivision of the strip width and thickness ranges, currently the thickness range matching the production capacity of the unit is 0.17 - 0.55 mm, and the width range is 700 - 1080 mm. Among them, the thickness is divided into 14 grades, which are 170, 180, 190, 200, 220, 250, 280, 300, 350, 400, 450, 500, 550, 600 respectively, and the width is divided into 5 grades, which are 700, 800, 900, 1000, 1080 respectively.

3. The tension setting method using cross slope according to claim 1, characterized in that, Step 2: Query the four point values of the regional boundaries in two dimensions, specifically as follows: The first dimension: Query the boundary values of the region where the strip thickness is located, which is realized through a data cursor. Define the total number of thickness grades TenThkCnt, then place the cursor at the lowest position. Each time the cursor moves, store a thickness value of TenThk into the thickness array TenThk[i] until all 14 thicknesses in TenThkCnt are stored in the corresponding array. The second dimension: For the strip thickness, do the same as above. Define the total number of width grades TenWidCnt, then place the cursor at the lowest position. Each time the cursor moves, store a width value of TenWid into the width array TenWid[i] until all 5 widths in TenWidCnt are stored in the corresponding array. When a new steel coil arrives at the uncoiler position, the first-level automation system will send a production data request. After receiving the request, the second-level process control system obtains the original information of the current coil based on the tracking position and organizes the corresponding production data. When organizing the tension values of each regional segment, first complete the upper and lower thresholds of the thickness in the first dimension. According to the strip thickness coil_thick, judge from low to high in sequence. If coil_thick > TenThk[i], then i is incremented by 1 and the cursor moves up one position until coil_thick < TenWid[i]. At this time, the two regional boundary values of the thickness obtained are TenThk[i - 1] and TenThk[i]; similarly, the two regional boundary values of the width in the second dimension are TenWid[i - 1] and TenWid[i]. Here is an explanation. If the original value exactly falls on the grade boundary, coil_thick = TenThk[i], then both regional boundary values are TenThk[i]; if the original value is lower (or higher) than the lowest (or highest) limit of the cursor, then both regional boundary values are TenThk[1] (or TenThk[max]).

4. The tension setting method using cross slope according to claim 1, characterized in that, Step 3: Use the "cross slope" to set the unit tension value, specifically as follows: Establish a rectangular coordinate system based on the thickness and width grades of the strip steel. Let the thickness of the strip steel be x, the width be y, and the unit tension of the strip steel be f(x, y). Let the lower limit of the thickness range of the strip steel be x1 and the upper limit be x2, and the lower limit of the width range of the strip steel be y1 and the upper limit be y2.

5. The tension setting method using cross slope according to claim 1, characterized in that, Step 3, based on the distribution of strip thickness and width, is divided into the following four cases: If the thickness and width values ​​of the strip steel fall exactly at the intersection of the thickness grade and width grade boundary values, then the value at that intersection is the unit tension of the strip steel. This value does not require slope correction; the unit tension can be obtained directly from a table. If x=x1, y=y1 then f(x, y)=f1; f(x, y) = f3; If x = x1, y = y2 then; If x=x2, y=y1 then f(x, y)=f2; If x=x2, y=y2 then f(x, y)=f4; In the formula: x: strip thickness; y: strip width x1: Lower limit of the thickness range; y1: Lower limit of the width range. x2: Upper limit of the thickness range; y2: Upper limit of the width range. f1: Tension value in one dimension obtained with x1 as the horizontal axis and y1 as the vertical axis. f2: Tension value in one dimension obtained with x2 as the horizontal axis and y1 as the vertical axis. f2: Tension value in one dimension obtained with x1 as the horizontal axis and y2 as the vertical axis. f2: Tension value in one dimension obtained with x2 as the horizontal axis and y2 as the vertical axis. f(x, y): The final actual tension of the strip steel. If the strip thickness falls exactly on the boundary value of the thickness grade, x = x1, then a single slope is used for fine adjustment of the tension value: Similarly, if the strip width value falls exactly on the boundary value of the width grade, y = y1, then Since the thickness and width of the strip lie at the right angle points of the region and are not on the boundary lines of the region, the point of tangency needs to be determined using the plane intersection slope: make Then, the product of the coefficients at the tangency point and the unit tension is used to achieve joint correction: f(x,y)=f1(x,y)+(f2(x,y)-f1(x,y))coey =f1+(f2-f1)coex+(f3+(f4-f3)coex-f1-(f2-f1)coex)coey =f1+(f2-f1)coex+(f3-f1)coey+(f4+f1-f2-f3)coex*coey, In the formula: coex: slope factor in the thickness dimension coey: Slope factor in the width dimension Finally, the total tension is obtained by multiplying the unit tension by the surface area.

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