A method for improving the edge bulging of thin strip steel coil

Abstract

The present invention belongs to the field of thin strip continuous casting, and relates to the plate shape control of thin strip steel and the coil shape control of steel coils, and specifically to a method for improving the local plate shape of thin strip steel and the coil shape of the edge of steel coils. The present invention achieves the purpose of improving the plate shape profile of the continuously cast thin strip steel and the coil shape of the thin strip steel by adjusting the water flow rate of the cooling water of the casting roller in real time during the continuous casting of the thin strip steel. The present invention detects the plate shape profile during the continuous casting of the thin strip steel, and calculates the maximum value of the difference between the actual plate shape profile value of the edge of the strip steel and the fitted quadratic curve fitting value through quadratic curve fitting, and establishes a mathematical model with the water flow rate of the casting roller cooling water and the maximum value. Through the method of the present invention, the plate shape profile of the edge of the thin strip steel can be improved, the problems of unstable thickness of the edge of the continuously cast thin strip steel and bulging of the edge of the thin strip steel coil can be solved, and the coil shape quality of the thin strip steel coil and the qualified rate of the product can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of thin strip steel continuous casting, and in particular to a production control method for improving bulging of a steel curling edge of a continuously cast thin strip steel. Background Art

[0002] The twin-roller thin strip continuous casting process is to let the liquid molten steel enter the molten pool formed by a pair of oppositely rotating casting rollers through the water distribution nozzle. The molten steel contacts the surface of the casting rollers with a lower temperature to form a solid shell. As the casting rollers rotate, it is guided out of the casting roller surface to form a continuous casting strip. The edge of the thin strip steel casting strip contacts the edge of the casting roller and the side sealing area of ​​the molten pool. The stress field, temperature field, and flow field in the area are greatly different from those in the central area. It is extremely difficult to control the strip quality in the edge area of ​​the strip.

[0003] The edge quality of continuous casting thin strip steel is closely related to the quality of the final thin strip steel hot-rolled coil. In the actual production process, the edge temperature of continuous casting thin strip steel is relatively high, the strength of the cast strip is relatively low, the thickness control of the thin strip steel edge is extremely difficult, and the edge thickness is uneven, which leads to instability in the subsequent hot rolling process and increases the difficulty of controlling the wave shape of the strip steel edge. The bulging of the hot-rolled thin strip steel edge caused by the thick edge thickness of the strip steel and the hot rolling edge wave has a serious impact on the quality of the thin strip steel coil.

[0004] In the prior art, the solution to the bulging of the edge of the strip steel coil mainly involves hot rolling control, annealing control or just early warning of the bulging of the steel coil. Chinese patent document 200710061593.2 discloses a finishing mill device that can control the bulging of the edge of medium and wide cold-rolled steel coils. By using a special curved roller type with a concave middle part for the working rolls of each finishing rolling stand, and a curved roller type with a chamfered end formed by a curve or a broken line for the support roll, the edge bulging problem is basically solved. Chinese patent document 201810691080.8 discloses a IF steel bulging defect control method, which adjusts the top roller chamber temperature of the flash cooling section of the annealing furnace according to the plate temperature of the flash cooling section, reduces the temperature difference between the plate rollers to improve the bulging, and the patent does not involve the solution to the edge bulging defect. Chinese patent document 201310134395.X discloses an online prediction method for the bulging defect of hot-rolled steel coils, which quantitatively predicts the degree of bulging defects by calculation methods, and does not involve edge bulging defects, let alone solutions to edge bulging defects.

[0005] It can be seen that the existing technologies all improve the local bulging of steel coils by improving hot rolling and subsequent processes, and do not involve the control of the thin strip steel continuous casting process. The existing technologies do not solve the problem of edge thickness control of thin strip steel continuous casting strips, and do not involve the control of edge bulging defects of thin strip steel coils under the thin strip continuous casting process.

[0006] Therefore, improving the edge bulging of thin strip steel during the thin strip continuous casting process is still a technical problem that needs to be solved in the art. Summary of the invention

[0007] The purpose of the present invention is to provide a production control method for improving the bulging of the edge of a thin strip steel coil. By comparing the thickness difference between the thin strip steel plate profile in the edge area and the ideal quadratic curve profile, a correlation model between the cooling water flow rate of the casting roller and the thickness difference is established, thereby improving the edge plate profile of the continuous casting thin strip steel, stabilizing the thickness of the edge area of ​​the thin strip steel, and improving the edge coil shape of the thin strip steel coil.

[0008] Specifically, the purpose of the present invention is achieved through the following technical solutions.

[0009] According to the method for improving the edge bulging of a thin strip steel coil of the present invention, the method comprises the following steps:

[0010] (1) measuring the thickness of the thin strip at multiple sampling points along the strip width L by a thickness measuring device to obtain data corresponding to multiple thicknesses at multiple sampling points;

[0011] (2) performing quadratic curve fitting on the data of multiple thicknesses and multiple sampling point positions, and obtaining the function value of the corresponding quadratic curve;

[0012] (3) taking multiple sampling points within the edge width E, measuring the actual thickness of the strip at each sampling point, and calculating the theoretical thickness of the strip at each sampling point based on the quadratic curve;

[0013] (4) calculating the difference between the theoretical thickness of the steel strip and the actual thickness of the steel strip at each sampling point, and obtaining the maximum value B among the multiple differences;

[0014] (5) The water inlet temperature T is measured at the water inlet and outlet of the cooling water channel of the casting roller. in , water outlet temperature T out , initial flow rate F0 of cooling water;

[0015] (6) According to the following formula:

[0016]

[0017] Calculate the required cooling water feedback flow F,

[0018] Where, F0 is the initial flow rate of cooling water, F is the feedback flow rate of cooling water, k is the thickness extreme value adjustment parameter (empirical parameter, determined according to actual conditions), w is the cooling water property parameter (related to the heat transfer properties of cooling water), B is the maximum value of the thickness difference of the sampling point, and h is the cooling water flow control parameter (depending on the quality control threshold of the edge bulge);

[0019] (7) The flow rate of cooling water is adjusted in real time according to the feedback flow rate F.

[0020] According to the method for improving edge bulging of a thin steel strip coil of the present invention, preferably, the steel strip width L is in the range of 400-2000 mm.

[0021] According to the method for improving edge bulging of a thin strip steel coil of the present invention, preferably, the edge width E has a value range of less than L / 2.

[0022] According to the method for improving edge bulging of a thin steel strip coil of the present invention, preferably, when measuring the thickness of the steel strip by a thickness measuring device, the interval between adjacent sampling points is 2-50 mm.

[0023] According to the method for improving edge bulging of a thin strip steel coil of the present invention, preferably, the value range of the thickness extreme value adjustment parameter k is k:5-25.

[0024] According to the method for improving edge bulging of a thin strip steel coil of the present invention, preferably, the value range of the cooling water property parameter w is w: 0.1-0.5.

[0025] According to the method for improving edge bulging of a thin strip steel coil of the present invention, preferably, the value range of the cooling water flow control parameter h is h≤0.3 mm.

[0026] According to the method for improving the edge bulging of a thin strip steel coil of the present invention, preferably, the water entering the cooling water channel of the casting roller is cooled by a cooling system.

[0027] According to the method for improving the edge bulging of a thin strip steel coil of the present invention, preferably, the inlet water temperature T in Specific outlet water temperature T out Low 2-15℃.

[0028] According to the method for improving edge bulging of a thin strip steel coil of the present invention, preferably, the thickness measuring device is a thickness measuring instrument.

[0029] Beneficial technical effects

[0030] The present invention fully considers the causes of bulging of the edge of steel coils during the production of thin strip steel, and for the first time compares and analyzes the plate profile of the continuously cast thin strip steel, especially the edge strip thickness. By fitting a quadratic curve, the deviation between the measured strip edge thickness and the ideal profile strip thickness is calculated. The edge thickness of the thin strip steel is controlled by controlling the water flow rate of the cooling water of the casting roller, thereby achieving the purpose of solving the problems of thick edge thickness of the thin strip steel, unstable edge thickness of the thin strip steel, and improving the plate profile of the edge of the thin strip steel and the curling shape of the edge of the steel coil.

[0031] The present invention establishes a feedback response model between the deviation between the actual edge thickness of thin strip steel and the ideal quadratic curve thickness and the water flow rate of cooling water of the casting roller, and timely responds to and adjusts the water flow rate of cooling water of the casting roller, thereby solving the problems of poor edge plate contour of thin strip steel and bulging of steel coil edges, and at the same time solves the difficulties in hot rolling and edge wavy problems caused by poor edge plate shape, thereby improving the product quality of thin strip steel and the quality of steel coils. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly introduce the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings of the embodiments. Obviously, the drawings in the following description only relate to some implementation cases of the present invention, and are not intended to limit the present invention.

[0033] Figure 1 It is a schematic diagram of the bulging edge of a thin strip steel coil in the prior art.

[0034] Figure 2 It is a schematic diagram of the shape of a continuously cast thin strip steel plate with bulging edges of the thin strip steel coil.

[0035] Figure 3 It is the thin strip steel coil shape of the present invention.

[0036] Figure 4 It is a schematic diagram of the plate shape profile of the continuous casting thin strip steel of the present invention.

[0037] Figure 5 It is a difference diagram between the actual thickness of the sampling point and the thickness of the quadratic curve in Example 1 of the present invention.

[0038] Figure 6 It is a difference diagram between the actual thickness of the sampling point and the thickness of the quadratic curve in Example 2 of the present invention.

[0039] Figure 7 It is a difference diagram between the actual thickness of the sampling point and the thickness of the quadratic curve in Example 3 of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one of ordinary skill in the art to which the present invention belongs.

[0042] See also Figure 1-Figure 4, showing the comparison between the prior art and the steel coil edge schematic diagram and the plate profile schematic diagram of the present invention. It can be seen that the problem of poor plate profile of the edge of thin strip steel and bulging of the steel coil edge is solved through the timely response and adjustment of the water flow rate of the cooling water of the casting roll of the present invention, and the product quality of thin strip steel and the quality of steel coil are improved.

[0043] The following will explain in conjunction with specific implementation methods.

[0044] Example 1

[0045] Twin-roller thin strip continuous casting of 500mm wide thin strip steel, real-time detection of the initial flow rate F0 of the casting roll cooling water during the continuous casting of thin strip steel is 800m 3 / h, inlet water temperature T in is 26℃, the outlet water temperature is T out It is 31 degrees Celsius.

[0046] The thickness tester is used to measure the thickness and plate shape profile data of the thin strip along the width direction. A sampling point is taken every 4 mm. The quadratic curve is fitted through the actual plate shape profile curve to obtain the quadratic curve function as follows:

[0047] y=1.64+9.15×10 -4 x-1.80×10 -6 x 2 .

[0048] Take the edge width E of the thin strip as 200mm, and measure the actual thickness of the strip at multiple sampling points within the edge width E, such as Figure 5 As shown by the solid line in the figure; and the theoretical thickness of the strip steel at multiple sampling points is calculated according to the above quadratic curve function, as shown in Figure 5 As shown by the dotted line in Figure 5 In the figure, the horizontal axis is the strip width and the vertical axis is the thickness value of the sampling point.

[0049] The difference between the theoretical thickness of the steel strip and the actual thickness of the steel strip at each sampling point was calculated, and the maximum value B (absolute value) among the multiple differences was 0.059 mm.

[0050] Take the thickness extreme value adjustment parameter k as 20, the cooling water property parameter w as 0.25, and the cooling water flow control parameter h as 0.05mm, according to the following formula:

[0051]

[0052] The calculated cooling water feedback flow rate F is 1395m 3 / h.

[0053] According to the feedback flow rate of the cooling water, the water flow rate F of the casting roll cooling water is adjusted to 1395m in real time. 3 / h, so as to gradually eliminate the edge thickness deviation of the continuously cast thin strip steel. In this embodiment, when the maximum value of the edge thickness deviation is less than 0.05mm, the water flow rate F0 of the cooling water of the casting roll is maintained constant.

[0054] Through the real-time feedback adjustment of the water flow rate of the casting roller cooling water, the thickness stability of the edge of the thin strip steel is improved, the plate profile is smooth, the hot rolling process is stable, and after coiling, the edge of the thin strip steel coil has no bulging and the coil shape is good.

[0055] Example 2

[0056] Twin-roller thin strip continuous casting 1400mm wide thin strip steel, real-time detection of the initial flow rate F0 of the casting roll cooling water during the thin strip continuous casting process is 1100m 3 / h, inlet water temperature T in is 20℃, the outlet water temperature is T out is 27℃.

[0057] Use a thickness detector to measure the thickness and plate profile data of thin strip steel along the width direction. Take a sampling point every 10 mm. Fit a quadratic curve through the actual plate profile curve to obtain the quadratic curve function as follows:

[0058] y=1.66+2.14×10 -4 x-1.53×10 -7 x 2 .

[0059] Take the edge width E of the thin strip as 500mm, and measure the actual thickness of the strip at multiple sampling points within the edge width E, such as Figure 6 As shown by the solid line in the figure; and the theoretical thickness of the strip steel at multiple sampling points is calculated according to the above quadratic curve function, as shown in Figure 6 As shown by the dotted line in Figure 6 In the figure, the horizontal axis is the strip width and the vertical axis is the thickness value of the sampling point.

[0060] The difference between the theoretical thickness of the steel strip and the actual thickness of the steel strip at each sampling point was calculated, and the maximum value B (absolute value) among the multiple differences was 0.047 mm.

[0061] Take the thickness extreme value adjustment parameter k as 14, the cooling water property parameter w as 0.18, and the cooling water flow control parameter h as 0.02mm, according to the following formula:

[0062]

[0063] The calculated cooling water feedback flow rate F is 1447m 3 / h.

[0064] According to the feedback flow rate of the cooling water, the water flow rate F of the casting roll cooling water is adjusted to 1447m in real time. 3 / h, so as to gradually eliminate the edge thickness deviation of the continuously cast thin strip steel. In this embodiment, when the maximum value of the edge thickness deviation is less than 0.02mm, the water flow rate F0 of the cooling water of the casting roll is maintained constant.

[0065] Through the real-time feedback adjustment of the water flow rate of the casting roller cooling water, the thickness stability of the edge of the thin strip steel is improved, the plate profile is smooth, the hot rolling process is stable, and after coiling, the edge of the thin strip steel coil has no bulging and the coil shape is good.

[0066] Example 3

[0067] Twin-roller thin strip continuous casting 1800mm wide thin strip steel, real-time detection of the initial flow rate F0 of the casting roll cooling water during the thin strip continuous casting process is 400m 3 / h, inlet water temperature T in is 36℃, the outlet water temperature is T out is 38℃.

[0068] The thickness tester is used to measure the thickness and plate shape profile data of thin strip steel along the width direction. A sampling point is taken every 18 mm. The quadratic curve is fitted through the actual plate shape profile curve to obtain the quadratic curve function as follows:

[0069] y=1.67+2.05×10 -4 x-1.21×10 -7 x 2 .

[0070] Take the edge width E of the thin strip as 750mm, and measure the actual thickness of the strip at multiple sampling points within the edge width E, such as Figure 7 As shown by the solid line in the figure; and the theoretical thickness of the strip steel at multiple sampling points is calculated according to the above quadratic curve function, as shown in Figure 7 As shown by the dotted line in Figure 7 In the figure, the horizontal axis is the strip width and the vertical axis is the thickness value of the sampling point.

[0071] The difference between the theoretical thickness of the steel strip and the actual thickness of the steel strip at each sampling point was calculated, and the maximum value B (absolute value) among the multiple differences was 0.106 mm.

[0072] Take the thickness extreme value adjustment parameter k as 8, the cooling water property parameter w as 0.36, and the cooling water flow control parameter h as 0.06mm, according to the following formula:

[0073]

[0074] The calculated cooling water feedback flow F is 1027m 3 / h.

[0075] According to the feedback flow rate of the cooling water, the water flow rate F of the casting roll cooling water is adjusted to 1027m in real time. 3 / h, so as to gradually eliminate the edge thickness deviation of the continuously cast thin strip steel. In this embodiment, when the maximum value of the edge thickness deviation is less than 0.06mm, the water flow rate F0 of the cooling water of the casting roll is maintained constant.

[0076] Through the real-time feedback adjustment of the water flow rate of the casting roller cooling water, the thickness stability of the edge of the thin strip steel is improved, the plate profile is smooth, the hot rolling process is stable, and after coiling, the edge of the thin strip steel coil has no bulging and the coil shape is good.

[0077] The above description is only a specific implementation of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for improving the edge bulging of a thin strip steel coil, characterized in that: The method comprises the following steps: (1) measuring the thickness of the thin strip at multiple sampling points along the strip width L by a thickness measuring device to obtain data corresponding to multiple thicknesses at multiple sampling points; (2) performing quadratic curve fitting on the data of multiple thicknesses and multiple sampling point positions, and obtaining the function value of the corresponding quadratic curve; (3) taking multiple sampling points within the edge width E, measuring the actual thickness of the strip at each sampling point, and calculating the theoretical thickness of the strip at each sampling point based on the quadratic curve; (4) calculating the difference between the theoretical thickness of the steel strip and the actual thickness of the steel strip at each sampling point, and obtaining the maximum value B among the multiple differences; (5) The water inlet temperature T is measured at the water inlet and outlet of the cooling water channel of the casting roller. in , water outlet temperature T out , initial flow rate F0 of cooling water; (6) According to the following formula: Calculate the required cooling water feedback flow F, In the formula, F0 is the initial flow rate of cooling water, F is the feedback flow rate of cooling water, k is the thickness extreme value adjustment parameter, w is the cooling water property parameter, B is the maximum value of the thickness difference of the sampling point, and h is the cooling water flow control parameter; (7) The flow rate of cooling water is adjusted in real time according to the feedback flow rate F.

2. The method for improving the edge bulging of a thin strip steel coil according to claim 1, characterized in that: The strip width L ranges from 400 to 2000 mm.

3. The method for improving the edge bulging of a thin strip steel coil according to claim 1, characterized in that: The value range of the edge width E is less than L / 2.

4. The method for improving the edge bulging of a thin strip steel coil according to claim 1, characterized in that: When measuring the thickness of the strip by a thickness measuring device, the interval between adjacent sampling points is 2-50mm.

5. The method for improving the edge bulging of a thin strip steel coil according to claim 1, characterized in that: The value range of thickness extreme value adjustment parameter k is k:5-25.

6. The method for improving the edge bulging of a thin strip steel coil according to claim 1, characterized in that: The value range of the cooling water property parameter w is w:0.1-0.

5.

7. The method for improving the edge bulging of a thin strip steel coil according to claim 1, characterized in that: The value range of the cooling water flow control parameter h is h≤0.3mm.

8. The method for improving the edge bulging of a thin strip steel coil according to claim 1, characterized in that: The water entering the cooling water channel of the casting roller is cooled by the cooling system.

9. The method for improving the edge bulging of a thin strip steel coil according to claim 1, characterized in that: The water temperature entering the casting roller cooling water channel is T in Specific outlet water temperature T out Low 2-15℃.

10. The method for improving the edge bulging of a thin strip steel coil according to claims 1 to 9, characterized in that: The thickness measuring device is a thickness gauge.

Images