Calculation method for process achievement rate during the heating process of steel billets in a hot rolling heating furnace

Abstract

The present invention relates to a method for calculating the process achievement rate during the heating process of billets in a hot rolling heating furnace, belonging to the technical field of steel rolling. The method is as follows: convert the target heating curve of the billet from the "time - temperature" coordinate to the "position - temperature" coordinate; set the judgment nodes on the curve considering the furnace temperature control and process requirements, and assign node weight coefficients; calculate the dimensionless temperature deviation between the average temperature of the billet at each node and the target temperature; calculate the process achievement rate between the target temperatures at each node using the piecewise function method; calculate the comprehensive process achievement rate of each node using the weighted average method. Through the conversion of the target heating curve, node division, dimensionless temperature deviation of node temperature, piecewise calculation of the hit accuracy of each node, and weighted average calculation of all nodes, the comprehensive process achievement rate of the target heating curve is finally obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of steel rolling, and relates to a calculation method for the process achievement rate during the heating process of steel billets in a hot rolling heating furnace. Background Art

[0002] Hot rolling is one of the very important processes in the steel production line, and the heating furnace is an important equipment in the hot rolling process, which has a great impact on the energy consumption and quality of the products. In modern hot rolling production, for higher-end products, the requirements for process control during the heating process are more stringent. Steel plants usually study the optimal process heating curve for high-end products and use an automatic combustion model to control the heating process of steel billets in order to achieve the purpose of improving and stabilizing the quality. However, the optimal heating curve obtained from process research is usually a "time-temperature" curve. Not only are different positions on the curve of different importance in terms of process, but there are inevitably production pauses such as heat preservation and waiting for rolling in actual production (as Figure 1 shown), which makes it difficult to intuitively evaluate the degree of conformity between the theory and the actual situation of the process heating curve. At present, the evaluation of the heating quality of steel billets in the heating furnace and the accuracy of the automatic combustion model control system generally uses result parameters such as the temperature uniformity at the furnace outlet, the residence time in the furnace, and the soaking time. There has always been a lack of an intuitive and reasonable index for evaluating the degree of conformity between the actual heating curve of the steel billet and the process target heating curve. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a calculation method for the process achievement rate during the heating process of steel billets in a hot rolling heating furnace.

[0004] To achieve the above purpose, the present invention provides the following technical solutions:

[0005] 1. The process heating curve is converted from a "time-temperature" curve to a "position along the furnace length - temperature" curve.

[0006] That is, substitute the relationship function t = f 1 (x) of the heating time and the position of the steel billet into the process curve T = f 2 (t), and obtain

[0007] T = f 3 (x) (1)

[0008] In formula (1), T is the temperature of the steel billet, t is the heating time of the steel billet, and x is the position of the steel billet along the furnace length direction.

[0009] 2. As Figure 1 shown, determine the judgment nodes on the curve by comprehensively considering the furnace temperature control and process requirements. The abscissa of the node is x i , the ordinate is T ti , and a weight coefficient w i. The subscript i represents the number of the node along the advancing direction of the billet in the furnace.

[0010] 3. Perform a thermal tracking model calculation on the heating process of the billet in the furnace. After the billet is discharged from the furnace, obtain the average temperature T of the billet at each node from the historical record data ai and the deviation from the process target temperature T ti , and convert it into a dimensionless temperature error:

[0011] ΔT i = |T ai - T ti | (2)

[0012] Define the process allowable deviation at node i as ΔT ei , then formula (2) can be converted into a dimensionless temperature deviation:

[0013]

[0014] Formulas (2) and (3) can be combined into the following formula:

[0015]

[0016] 4. Use the dimensionless error as the independent variable to calculate the hit accuracy score at each node in segments, so that the score within the process allowable deviation range decreases linearly, and the score outside the process allowable deviation range quickly approaches zero. As Figure 2 shown, define the score when e i = 0 as 100, and the score when e i = 1 as R ei , and calculate the hit accuracy score at each node in segments:

[0017]

[0018] In the above formula, the exponent n >> 1.

[0019] 5. Perform a weighted average calculation on the hit accuracy scores of each node to obtain the comprehensive process achievement rate index as:

[0020]

[0021] The beneficial effects of the present invention are as follows: The present invention can not only evaluate the coincidence degree between the actual heating process of the billet and the process heating curve, but also set different weight coefficients for the nodes of the heating curve to achieve key control of key process nodes, and has good engineering application prospects in aspects such as process control accuracy evaluation, production statistical reports, process quality analysis and improvement of the automatic combustion model of the heating furnace.

[0022] Other advantages, objects, and features of the present invention will be set forth in part in the following description, and in part will be obvious to those skilled in the art upon examination of the following, or may be learned from the practice of the present invention. The objects and other advantages of the present invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, where:

[0024] Figure 1 is a schematic diagram of a process target curve, an actual heating curve, and node division;

[0025] Figure 2 is a segmented curve of the billet temperature hit rate at the node. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The following specific examples illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present invention schematically. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0027] Among them, the drawings are only for illustrative purposes and show only schematic diagrams, not physical diagrams, and should not be construed as a limitation to the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged, or reduced, and do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0028] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and should not be construed as a limitation to the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0029] Please refer to Figures 1 to 2, the following is an example of the model thermal tracking data of a certain billet product produced by a hot rolling reheating furnace, and the hit rate of the heating curve during the billet heating process is calculated.

[0030] 1. Assume that the process target heating curve of the billet is T = f 2 (t). According to the charging and discharging positions of the billet and the condition that the billet moves uniformly in the furnace during normal production, a linear relationship between the heating time t and the billet position x, t = f 1 (x), can be obtained. Substitute this equation into T = f 2 (t) to get the "position - temperature" target curve T = f 3 (x).

[0031] 2. Determine the judgment nodes on the curve by integrating furnace temperature control and process requirements. In this sample, as shown in Table 1, the furnace temperature control nodes are at the end of each furnace temperature control section in the furnace, and the process requirement points are the Fe - C alloy phase transformation points. The abscissa of the node is x i , and the ordinate is T ti , and a weight coefficient w i is given to the node according to the process requirements. The data of this sample is shown in Table 1.

[0032] 3. According to factors such as the billet inlet temperature, steel grade, size, and position in the furnace, use the heat transfer model to track and calculate the average temperature T a of the billet. After the billet is discharged from the furnace, obtain the average temperature T ai of the billet at each node from the historical record data, and calculate the deviation between the average temperature T ti of the billet at each node and the process target temperature T i = |T ai - T ti |, and convert it into a dimensionless temperature error ΔT i = ΔT i / ΔT ei . The data of this sample is shown in Table 1.

[0033] 4. Use the dimensionless error as the independent variable to calculate the hit accuracy score at each node in segments, so that the score within the process tolerance range decreases linearly and the score outside the process tolerance range quickly approaches zero. In this sample, assume that at the segmentation point e i = 1 of the piecewise function, R ei = 60, and the exponent n = 20 in formula (5). Calculate the hit accuracy score at each node according to formula (5). The data of this sample is shown in Table 1.

[0034] According to the data in Table 1 of this sample, calculate the comprehensive process achievement rate R using formula (6). The result of this sample is R = 81.5.

[0035] Table 1 Sample Data Table

[0036]

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A calculation method for the process achievement rate during the heating of steel billets in a hot rolling heating furnace, Characterized in that: This method includes the following steps: S1: Convert the process heating curve from a "time - temperature" curve to a "position in the furnace length direction - temperature" curve; Let the process target heating curve of the billet be T = f 2 (t). According to the charging and discharging positions of the billet and the condition that the billet moves forward uniformly in the furnace during normal production, a linear relationship between the heating time t and the billet position x, t = f 1 (x), is obtained. Substitute this equation into T = f 2 (t) to get the "position-temperature" target curve T = f 3 (x); S2: Set the judgment nodes on the curve by integrating furnace temperature control and process requirements; S3: Perform thermal tracking model calculations on the heating process of the billet in the furnace. After the billet is discharged from the furnace, obtain the average temperature T of the billet at each node from the historical record data ai and the deviation from the process target temperature T ti and convert it into a dimensionless temperature error; S4: Use the dimensionless error as the independent variable, and calculate the hit accuracy scores at each node in segments, making the scores within the process tolerance range decrease linearly and the scores outside the process tolerance range quickly approach zero; S5: Calculate the weighted average of the hit accuracy scores of each node to obtain the comprehensive process achievement rate index.

2. The calculation method for the process achievement rate during the heating of steel billets in a hot rolling heating furnace according to claim 1, Characterized in that: In S2, the abscissa of the node is x i , and the ordinate is T ti , and the weight coefficient w of the node is given according to the process requirements i ; the subscript i represents the number of the node along the advancing direction of the billet in the furnace.

3. The calculation method for the process achievement rate during the heating of steel billets in a hot rolling heating furnace according to claim 2, Characterized in that: In the said S3, the dimensionless temperature error is: ΔT i = |T ai - T ti | (2) Define the process tolerance deviation at node i as ΔT ei , then formula (2) is converted into a dimensionless temperature deviation: Formula (2) and formula (3) are combined into the following formula:

4. The calculation method for the process achievement rate during the heating of steel billets in a hot rolling heating furnace according to claim 3, Characterized in that: In S4, it is defined that when e i = 0, the score is 100, and when e i = 1, the score is R ei , and the hit accuracy scores at each node are calculated in segments: In the above formula, the exponent n >> 1.

5. The calculation method for the process achievement rate during the heating of steel billets in a hot rolling heating furnace according to claim 4, Characterized in that: In the said S5, the comprehensive process achievement rate index is:

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