A method for early warning of friction / lubrication index during online width adjustment of wide and thick slab continuous casting billet

Abstract

A kind of wide plate continuous casting billet online width adjustment friction / lubrication index early warning method, by the detection of continuous casting billet shell thickness, calculate friction index and temperature index are carried out in the online width adjustment process to the early warning judgment of continuous casting billet breakout.By the comprehensive analysis to liquid slag layer thickness, mold friction and the temperature change data of mold inner wall, can accurately, real-time give the risk of breakout due to the change of lubrication condition in the mold in the online width adjustment process in the mold, so as to give width adjustment instruction pause and continue, solve the situation that original detection data is not applicable in the online width adjustment process, reduce the risk of pulling out in the width adjustment process.

Description

Technical Field

[0001] This invention belongs to the field of continuous casting technology, specifically relating to a method for early warning of friction / lubrication index during online width adjustment of wide and thick plate continuous casting billets. Background Technology

[0002] In modern large slab continuous casting technology, with the continuous expansion of the market for small-batch and customized production of slabs and strips, steel enterprises have placed higher demands on the continuous casting process to produce slabs with complex cross-sectional changes in order to increase the number of continuous casting furnaces, improve casting machine efficiency, save energy, and reduce production costs. This has led to the development of online tundish width adjustment technology, which has begun to be applied to industrial production by advanced foreign steel enterprises. my country is a veritable world steel powerhouse, with its steel production exceeding 50% of the world's total steel production for many consecutive years. Currently, apart from a few recently imported advanced large slab continuous casting machines, most continuous casting machines do not have online hot width adjustment capabilities. With advancements in tundish longevity and quick-change technologies, and the increasing demand from steel enterprises for slabs with complex cross-sectional changes, online width adjustment technology has become a limiting factor in improving the efficiency of slab continuous casting and addressing the increased workload and difficulty of customized production in the rolling process.

[0003] The online width adjustment process for thick plate continuous casting billets involves the slow compression of the solidified billet shell by the mold plate under the action of hydraulic pushers during production, thereby reducing the cross-sectional area. During this process, the liquid slag inflow channel between the billet shell and the inner wall of the mold is narrow and unstable, and the thickness of the liquid slag layer also changes significantly. This increases the friction between the solidified billet shell and the inner wall of the mold, leading to unstable lubrication and an increased risk of steel leakage. If steel leakage occurs, the width adjustment progress will be affected, or even the casting process may be halted. Therefore, a method for comprehensively predicting and warning of friction / lubrication indices during online width adjustment is needed to provide guidance for the process. Summary of the Invention

[0004] To overcome the above shortcomings, this invention provides a method for early warning of friction / lubrication index during online width adjustment of thick plate continuous casting billets. This method, by adding an ultrasonic liquid slag thickness measuring device, analyzes the data on liquid slag layer thickness, crystallizer friction force, and crystallizer inner wall temperature change, and can accurately and in real time give the risk level of steel leakage in the crystallizer, so as to control the action command of the width adjustment process during online width adjustment.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for early warning of friction and lubrication during online width adjustment of thick plate continuous casting billets, the specific steps of which are as follows: S1. Install three sets of ultrasonic transmitting and receiving devices with long wavelength, medium wavelength and short wavelength at a distance of 0.5 to 1.5 meters above the mold protective slag, and use the time difference between ultrasonic transmission and reception to detect the thickness of the continuous casting billet shell online. S2. After online width adjustment is started, retrieve the friction force M change data for the period of 1 to 3 minutes before start-up, extract the maximum friction tension M (qmax) and maximum friction pressure M (qymax) during the period before start-up, extract the real-time friction tension M and friction pressure My during online width adjustment, and obtain the friction force index M (v) through mathematical processing methods. S3. After the online width adjustment is started, retrieve the temperature data within 50-500 mm below the meniscus of the crystallizer inner wall in the time period 1-3 minutes before the start and calculate the average temperature value Tq(i) at each position. Extract the real-time temperature T(i) within 50-500 mm below the meniscus of the crystallizer inner wall during the online width adjustment process and obtain the temperature index T(v) through mathematical processing. S4. Based on the friction index in step S2 and the temperature index in step S3, a warning judgment is made. Further optimization involves the long-wavelength signal being reflected as a strong signal at the air-slag interface and received by the receiving antenna, the medium-wavelength signal being reflected as a strong signal at the slag-liquid slag interface and received by the receiving antenna, and the short-wavelength signal being reflected as a strong signal at the slag-steel interface and received by the receiving antenna.

[0006] Further optimization is achieved by specifying that the long wavelength is 4–10 mm, the medium wavelength is 1–2 mm, and the short wavelength is 0.05–0.5 mm.

[0007] Further optimization is achieved by including the following methods for early warning judgment in step S4: (1) When M≥1.2*M(qmax) or My≥1.1*M(qymax) or T(i)-Tq(i)≥40, the online width adjustment warning issues a pause width adjustment instruction, and waits for the online width adjustment warning condition to be met again before continuing the action instruction, and then the online width adjustment process is carried out again. (2) When M<1.2*M(qmax), My<1.1*M(qymax), and T(i)-Tq(i)<40 are satisfied at the same time, the comprehensive friction force / lubrication index Z is judged.

[0008] Further optimization includes the following two cases for determining the comprehensive friction / lubrication index Z: a. When Z≥1.25, the online width adjustment early warning judgment issues a pause width adjustment command, and waits for the online width adjustment early warning condition to be met again before continuing the operation command, and then the online width adjustment process is carried out again. b. When Z < 1.25, the online width adjustment early warning judgment issues a continue action command.

[0009] The beneficial effects of this invention are as follows: By comprehensively analyzing data on the thickness of the liquid slag layer, the friction force of the crystallizer, and the temperature change of the inner wall of the crystallizer, it is possible to accurately and in real time provide information on the risk of steel leakage due to changes in the lubrication conditions inside the crystallizer during the online width adjustment process. This allows for the issuance of instructions to pause or continue the width adjustment, resolving situations where the original detection data is inapplicable during the online width adjustment process and reducing the risk of steel leakage during the width adjustment process. Attached Figure Description

[0010] Figure 1 Schematic diagram of online bandwidth adjustment early warning judgment principle; Figure 2 Principle of measuring the thickness of the liquid slag layer inside the crystallizer; Figure 3 Calculation of frictional force in crystallizer; Figure 4 Temperature at different locations within the crystallizer. Detailed Implementation

[0011] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be described in detail below with reference to specific embodiments. The following embodiments are implemented based on the technical solutions of the present invention, and provide detailed implementation methods and specific operation processes. However, the present invention can also be implemented in other ways different from those described herein, so the scope of protection of the present invention is not limited to the following embodiments.

[0012] A method for judging friction / lubrication early warning during online width adjustment of thick plate continuous casting billets, the specific steps of which are as follows: S1. The ultrasonic liquid slag thickness measurement method is as follows: Three sets of continuous ultrasonic transmitting and receiving devices with long wavelength, medium wavelength, and short wavelength are installed 1.2 meters above the protective slag in the crystallizer. The long wavelength band is 4-10 mm, and its signal is reflected strongly at the air-powder slag interface and received by the receiving antenna. The medium wavelength band is 1-2 mm, and its signal is reflected strongly at the powder slag-liquid slag interface and received by the receiving antenna. The short wavelength band is 0.1 mm, and its signal is reflected strongly at the liquid slag-molten steel interface and received by the receiving antenna. The received echo signal is filtered and amplified after signal processing and converted into a signal containing time and distance information. The difference between the ultrasonic transmitting position and the three different interface positions is calculated by computer to obtain the thickness value of the protective slag liquid slag layer in the crystallizer. The method for calculating the liquid slag thickness index of the protective slag is as follows: After online width adjustment is started, retrieve the liquid slag layer thickness change data for the period 3 minutes before start-up; extract the minimum liquid slag thickness h(qmix) within the period before start-up, such as h(qmix) = 4mm; extract the real-time liquid slag thickness h during online width adjustment, such as h = 6mm; obtain the liquid slag layer thickness index change value h(v) using mathematical processing methods, defined as: h(v)=h / h(qmix)=6 / 4=1.5.

[0013] S2. Friction index calculation method, where the principle of friction calculation is that under the same vibration frequency, amplitude and non-sinusoidal factor conditions, the difference in output force of the hydraulic vibration system in the casting machine in the billet-drawing state and the undrawing state is the crystallizer friction force M. The specific method for calculating the friction index is as follows: After online pulse width adjustment is started, retrieve the crystallizer friction force M change data for the period 1-3 minutes before start-up; extract the maximum friction tension M(qmax) and maximum friction pressure M(qymax) during the period before start-up; extract the real-time crystallizer friction tension M and friction pressure My during online pulse width adjustment, such as M = 18kN, My = 16kN; obtain the friction index M(v) using mathematical processing methods, defined as: M(v)=M(qmax) / M=20 / 18=1.11.

[0014] S3. The method for calculating the temperature index of the inner wall of the crystallizer is as follows: After the online width adjustment is started, retrieve the temperature data within 50-500 mm below the meniscus of the inner wall of the crystallizer during the period of 1-3 minutes before the start-up and calculate the average temperature value Tq(i) at each location, where i is the serial number of different locations; extract the real-time temperature T(i) within 50-500 mm below the meniscus of the inner wall of the crystallizer during the online width adjustment process, where i is the serial number of different locations; Figure 4 The values ​​are the temperature measurements at 45 and 400 mm below the meniscus and the average temperature over the previous minute. For example, at 1580 s, T(1) = 100 ℃ and Tq(1) = 152 ℃. The temperature index (T(v)) is obtained using mathematical processing methods and is defined as follows: T(v)=Tq(i) / T(i)=152 / 100=1.52.

[0015] S4. Warning judgment logic method, specifically including the following situations: (1) When M≥1.2*M(qmax) or My≥1.1*M(qymax) or T(i)-Tq(i)≥40, the online width adjustment warning judgment issues a pause width adjustment command. Taking 1580s as an example, T(1)=100℃, Tq(1)=152℃, |T(i)-Tq(i)|=100-152=42≥40℃. At this time, the online width adjustment warning judgment issues a pause width adjustment command. After the online width adjustment warning judgment condition is met again, the online width adjustment process will be carried out again. (2) When M<1.2*M(qmax), My<1.1*M(qymax), and T(i)-Tq(i)<40 are simultaneously satisfied, the comprehensive friction force / lubrication index Z is judged. If h(v)<1; Z=b*M(v)+c*T(v), b=b1, c=c1, where b1=0.7, c1=0.45; if h(v)>1; Z=b*M(v)+c*T(v), b=b2, c=c2, where b1=0.6, c1=0.5, b, c, b1, c1 are coefficients. This judgment includes the following two cases: a. When Z≥1.25, the online width adjustment early warning judgment issues a pause width adjustment command, and waits for the online width adjustment early warning judgment condition to be met again to continue the operation command before the online width adjustment process is restarted; b. When Z < 1.25, the online width adjustment early warning judgment issues a continue action command.

[0016] By comprehensively analyzing data on the thickness of the liquid slag layer, the friction force of the crystallizer, and the temperature change of the inner wall of the crystallizer, it is possible to accurately and in real time provide information on the risk of steel leakage due to changes in the lubrication conditions inside the crystallizer during the online width adjustment process. This allows for the issuance of instructions to pause or continue the width adjustment, resolving situations where the original detection data is inapplicable during the online width adjustment process, reducing the risk of steel leakage during the width adjustment process, and preventing the width adjustment progress from being affected or even causing a shutdown.

[0017] The foregoing has shown and described the main features, usage methods, basic principles, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention based on actual circumstances without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for early warning of friction / lubrication index during online width adjustment of thick plate continuous casting billets, characterized in that, The specific steps are as follows: S1. Install three sets of ultrasonic transmitting and receiving devices (long-wavelength, medium-wavelength, and short-wavelength) at a distance of 0.5-1.5 meters above the protective slag in the crystallizer. Utilize the time difference between ultrasonic wave transmission and reception to perform online detection of the slag-liquid layer thickness. The slag-liquid layer thickness exponential change value h(v) satisfies the following formula: h is the real-time liquid sludge thickness during the online width adjustment process, and h(qmix) is the minimum liquid sludge thickness within the time period before startup. S2. After online width adjustment is started, retrieve the friction force M change data for the period 1-3 minutes before start-up, extract the maximum friction tension M (qmax) and maximum friction pressure M (qymax) during the period before start-up, extract the real-time friction tension M and friction pressure My during online width adjustment, and obtain the friction force index M (v) through mathematical processing methods. ; S3. After online width adjustment is started, retrieve the temperature data within 50-500 mm below the meniscus of the crystallizer inner wall during the 1-3 minute period before start-up and calculate the average temperature value Tq(i) at each location. Extract the real-time temperature T(i) within 50-500 mm below the meniscus of the crystallizer inner wall during online width adjustment and obtain the temperature index T(v) through mathematical processing. ; S4. Combine the friction index in step S2 and the temperature index in step S3 to make an early warning judgment; The methods for early warning judgment in step S4 include the following situations: (1) When M≥1.2*M(qmax) or My ≥1.1*M(qymax) or T(i)-Tq(i)≥40, the online width adjustment warning judgment issues a pause width adjustment instruction, and waits for the online width adjustment warning judgment condition to be met again before continuing the action instruction, and then the online width adjustment process is carried out again. (2) When M < 1.2 * M(qmax), My < 1.1 * M(qymax), and T(i) - Tq(i) < 40 are simultaneously satisfied, the comprehensive friction / lubrication index Z is judged. If h(v) < 1, Z = b * M(v) + c * T(v), b = b1, c = c1, where b1 = 0.7, c1 = 0.45; if h(v) > 1, Z = b * M(v) + c * T(v), b = b2, c = c2, where b2 = 0.6, c2 = 0.5; the comprehensive friction / lubrication index Z judgment includes the following two cases: a. When Z≥1.25, the online width adjustment early warning judgment issues a pause width adjustment command, and waits for the online width adjustment early warning judgment condition to be met again to continue the operation command before the online width adjustment process is restarted; b. When Z < 1.25, the online width adjustment early warning judgment issues a continue action command.

2. The method for early warning of friction / lubrication index during online width adjustment of thick plate continuous casting billets as described in claim 1, characterized in that, The long-wavelength signal is reflected strongly at the air-slag interface and received by the receiving antenna; the medium-wavelength signal is reflected strongly at the slag-liquid slag interface and received by the receiving antenna; and the short-wavelength signal is reflected strongly at the slag-molten steel interface and received by the receiving antenna.

3. The method for early warning of friction / lubrication index during online width adjustment of thick plate continuous casting billets as described in claim 1, characterized in that, The long wavelength is 4~10mm, the medium wavelength is 1~2mm, and the short wavelength is 0.05~0.5mm.

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