Method for on-line control of the length of hot rolling of seamless steel pipes

Abstract

A method for online control of the hot rolling length of seamless steel pipes first establishes tracking for each steel pipe from the start of the self-heating furnace steel extraction signal to the end of the steel pipe rolling process in the tension reduction mill. Then, for each steel pipe, before the tension reduction mill receives the signal after the continuous rolling mill has finished rolling, the dynamic tension strength coefficient based on the current continuous rolling measurement length of the steel pipe is calculated and issued. The issued dynamic tension strength coefficient is used as the set tension strength coefficient for the steel pipe entering the tension reduction mill for rolling, thus completing the rolling operation of the current steel pipe in the tension reduction mill. This method for online control of the hot rolling length of seamless steel pipes improves the yield of hot-rolled products by establishing dynamic rolling length control for each steel pipe, and can also adapt well to small-batch steel pipe production.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical production technology, specifically relating to an online control method for the hot rolling length of seamless steel pipes. Background Technology

[0002] The basic production process of hot-rolled seamless steel pipes is as follows: after the billet is heated in a furnace, it passes through a piercing mill and a continuous rolling mill to obtain a steel pipe with an intermediate wall thickness and length. Then, it is rolled by a tension reduction mill to obtain the finished hot-rolled steel pipe. Hot-rolled seamless steel pipes are managed and produced in batches, with each batch corresponding to the same product specifications and generally using the same rolling process parameters for production control. In actual control, fluctuations in equipment status and process control, such as inconsistent oxidation loss due to heating time and temperature fluctuations, and uneven wall thickness during rolling, can affect the final length of the finished steel pipe. When online pipe length measurement devices are lacking, on-site production mainly relies on sampling inspection, i.e., randomly selecting a portion of the steel pipes in a batch and measuring their length offline to ensure they are within acceptable limits, thus preventing batches of steel pipes from failing to meet finished product requirements. Now, advanced hot-rolled seamless steel pipe production lines install online laser length measuring devices. When on-site production technicians detect abnormal pipe lengths, they adjust the rolling parameters based on production experience to achieve effective control over the pipe length. Existing control methods cannot achieve online dynamic control of the length of each individual steel pipe. In particular, the intervention and adjustment of length control by different technicians based on production experience introduces human differences, which is not conducive to precise product control. Furthermore, the current trend in seamless steel pipe production is shifting from large-scale centralized production to multi-variety, small-batch production, making the necessity of online dynamic control of steel pipe length even more urgent.

[0003] The invention application with application number CN201710272775.8 discloses "a method for controlling the thickness of intermediate billets and the length of ingots in hot continuous rolling mills". This method calculates the intermediate billet thickness reference value and the reduction amount of each rolling pass based on the set reduction rate of each stand in the continuous rolling mill and the finished product thickness of the rolled piece. The intermediate billet thickness reference value is then checked and corrected using rolling force. If the calculated rolling force exceeds the maximum allowable rolling force value of the stand, the reduction amount of that pass is reduced. This process is iterated repeatedly until the calculated rolling force is less than or equal to the maximum allowable rolling force value. The intermediate billet thickness reference value is then corrected, and the billet is rolled to the calculated intermediate billet thickness in the roughing mill. The ingot length is calculated based on the corrected intermediate billet thickness value, the length of the roller table between the roughing mill and the continuous rolling mill, and the ingot thickness. The ingot is then cast according to the calculated ingot length. Summary of the Invention

[0004] To address the above problems, this invention provides an online control method for the hot rolling length of seamless steel pipes, the specific technical solution of which is as follows:

[0005] A method for online control of the hot rolling length of seamless steel pipes, characterized in that:

[0006] First, a tracking system is established for each steel pipe from the start of the self-heating furnace steel extraction signal to the end of the steel pipe rolling process in the tension reduction mill. Then, for each steel pipe, before the tension reduction mill receives the signal after the continuous rolling mill has finished rolling, the dynamic tension strength coefficient based on the current continuous rolling measurement length of the steel pipe is calculated and issued. The issued dynamic tension strength coefficient is used as the set tension strength coefficient for the steel pipe to enter the tension reduction mill for rolling, thus completing the rolling operation of the current steel pipe in the tension reduction mill.

[0007] According to the present invention, a method for online control of the hot rolling length of seamless steel pipes is characterized in that:

[0008] The calculation of the dynamic tensile strength coefficient based on the current continuous rolling measurement length of the steel pipe is specifically determined by the following formula:

[0009]

[0010] In the formula,

[0011] a and b: Both are regression coefficients.

[0012] According to the present invention, a method for online control of the hot rolling length of seamless steel pipes is characterized in that:

[0013] The regression coefficients a and b are determined based on historical continuous rolling measurement lengths, historical tension reduction measurement lengths, historical actual tensile strength coefficients, and the following formula, using least squares regression:

[0014]

[0015] in:

[0016] y: Tension reduction length of steel pipe;

[0017] x: tensile strength coefficient;

[0018] L: Continuous rolling length.

[0019] According to the present invention, a method for online control of the hot rolling length of seamless steel pipes is characterized in that:

[0020] The historical data used for regression is used to classify the sample space according to three parameters: steel grade, finished product outer diameter, and finished product wall thickness. Different categories are formed based on the same steel grade, finished product outer diameter, and finished product wall thickness. Then, regression coefficients corresponding to different categories are obtained.

[0021] According to the present invention, a method for online control of the hot rolling length of seamless steel pipes is characterized in that:

[0022] The online rolling length control method also establishes anomaly detection and handling mechanisms for steel pipe length control through the following anomaly detection settings:

[0023] First, after each steel pipe is rolled by the tension reduction mill, the post-calculated tensile strength coefficient of the steel pipe is determined based on the obtained corresponding tension reduction measurement length.

[0024] Then, the determined post-calculated tensile strength coefficients are compared laterally and analyzed longitudinally; the anomalies in the steel pipe are determined by combining the comparison of laterally and the analysis of longitudinally.

[0025] According to the present invention, a method for online control of the hot rolling length of seamless steel pipes is characterized in that:

[0026] The aforementioned lateral numerical comparison is accomplished by calculating the difference between the post-calculated tensile strength coefficient and the theoretical tensile strength coefficient for each current steel pipe.

[0027] The longitudinal numerical analysis is completed by statistically analyzing the overall distribution of all post-tension strength coefficients before the current steel pipe relative to the theoretical tension strength coefficient.

[0028] When the absolute value of the difference is greater than or equal to the set threshold, and the overall distribution of the post-tension strength coefficient relative to the theoretical tension strength coefficient is oscillating, it is determined that the current steel pipe length control is abnormal and a prompt is issued.

[0029] When the overall distribution of the post-tension strength coefficient relative to the theoretical tension strength coefficient shows a unidirectional and gradually increasing trend of difference, a risk warning is issued regarding the deterioration of the current steel pipe length control trend.

[0030] According to the present invention, a method for online control of the hot rolling length of seamless steel pipes is characterized in that:

[0031] The post-calculated tensile strength coefficient is determined according to the following formula:

[0032]

[0033] In the formula,

[0034] a and b: Both are regression coefficients.

[0035] According to the present invention, a method for online control of the hot rolling length of seamless steel pipes is characterized in that:

[0036] The theoretical tensile strength coefficient is determined according to the following formula:

[0037]

[0038] In the formula,

[0039] a and b: Both are regression coefficients.

[0040] According to the present invention, a method for online control of the hot rolling length of seamless steel pipes is characterized by the following specific steps:

[0041] S1: When issuing process parameters and set values ​​based on the current rolling plan to L2, determine the regression coefficients that match the current rolling plan together;

[0042] S2: When L1 receives the steel extraction signal from the heating furnace, it establishes queue-based tracking for the steel pipes exiting the furnace.

[0043] S3: After the steel pipe completes continuous rolling based on the continuous rolling mill, the dynamic tensile strength coefficient of the steel pipe is calculated based on the real-time obtained continuous rolling measurement length, and the tensile strength coefficient of the steel pipe is issued before the steel pipe enters the rolling operation of the tension reduction mill.

[0044] S4: After the steel pipe is rolled using a tension reduction mill, obtain the corresponding tension reduction measurement length.

[0045] According to the present invention, a method for online control of the hot rolling length of seamless steel pipes is characterized by the following specific steps:

[0046] SS1: When L1 receives the steel extraction signal from the heating furnace, it establishes queue-based tracking for the steel pipes exiting the furnace.

[0047] SS2: After the steel pipe completes continuous rolling based on the continuous rolling mill, the dynamic tensile strength coefficient of the steel pipe is calculated based on the real-time obtained continuous rolling measurement length, and the tensile strength coefficient of the steel pipe is issued before the steel pipe enters the rolling operation of the tension reduction mill.

[0048] SS3: After the steel pipe is rolled using a tension reduction mill, the corresponding tension reduction measurement length is obtained, and the post-calculated tensile strength coefficient is calculated based on the continuous rolling measurement length and the tension reduction measurement length.

[0049] SS4: Based on the comparison of transverse and longitudinal numerical values ​​using the post-calculated tensile strength coefficient, complete the anomaly determination of the steel pipe and provide an anomaly alert.

[0050] According to the present invention, a method for online control of the hot rolling length of seamless steel pipes is characterized in that:

[0051] The anomaly determination can also be based on a comparison between the measured length of the tension reduction and the theoretical length of the tension reduction.

[0052] This invention discloses an online control method for the hot rolling length of seamless steel pipes. First, it uses historical data to linearly regress the regression coefficients of the tension strength coefficient equation of the tension reduction mill. During regression, a classification regression is established according to steel grade and specification, forming regression coefficients matched with different steel grades and specifications. Then, during actual rolling, the regression coefficients matched with the current rolling plan are acquired along with other process parameters and setpoints. In actual production, a pipe-by-pipe tracking system is established from the start of the self-heating furnace steel extraction signal to the end of the pipe rolling process on the tension reduction mill. Based on the calculation and distribution of the dynamic tension strength coefficient for each pipe, the rolling length of each pipe is controlled. Simultaneously, anomaly detection and handling for pipe length control are established based on the post-calculated tension strength coefficient. In summary, this invention's online control method for the hot rolling length of seamless steel pipes improves the yield of hot-rolled products by establishing dynamic rolling length control for each pipe, and also adapts well to small-batch steel pipe production. Attached Figure Description

[0053] Figure 1 This is a schematic diagram illustrating the overall working principle of the present invention;

[0054] Figure 2 This is a flowchart of the dynamic control steps based on different steel grades in this invention;

[0055] Figure 3 This is a schematic diagram of the dynamic control steps of the present invention. Detailed Implementation

[0056] The following is a detailed description of an online control method for the hot rolling length of seamless steel pipes according to the present invention, based on the accompanying drawings and specific embodiments.

[0057] like Figure 1 , 2 The following is a method for online control of the hot rolling length of seamless steel pipes, as shown in Figure 3. First, the tracking of each steel pipe is established from the start of the steel extraction signal from the self-heating furnace to the end of the steel pipe rolling in the tension reduction mill. Then, for each steel pipe, before the steel pipe rolling in the continuous rolling mill is completed and before the tension reduction mill receives the signal, the dynamic tension strength coefficient based on the current continuous rolling measurement length of the steel pipe is calculated and issued. The issued dynamic tension strength coefficient is used as the set tension strength coefficient for the steel pipe to enter the tension reduction mill for rolling, thus completing the rolling operation of the current steel pipe in the tension reduction mill.

[0058] in,

[0059] The calculation of the dynamic tensile strength coefficient based on the current continuous rolling measurement length of the steel pipe is specifically determined by the following formula:

[0060]

[0061] In the formula,

[0062] a and b: Both are regression coefficients.

[0063] in,

[0064] The regression coefficients a and b are determined based on historical continuous rolling measurement lengths, historical tension reduction measurement lengths, historical actual tensile strength coefficients, and the following formula, using least squares regression:

[0065]

[0066] in:

[0067] y: Tension reduction length of steel pipe;

[0068] x: tensile strength coefficient;

[0069] L: Continuous rolling length.

[0070] in,

[0071] The historical data used for regression is used to classify the sample space according to three parameters: steel grade, finished product outer diameter, and finished product wall thickness. Different categories are formed based on the same steel grade, finished product outer diameter, and finished product wall thickness. Then, regression coefficients corresponding to different categories are obtained.

[0072] The specific steps are as follows:

[0073] S1: When issuing process parameters and set values ​​based on the current rolling plan to L2, determine the regression coefficients that match the current rolling plan together;

[0074] S2: When L1 receives the steel extraction signal from the heating furnace, it establishes queue-based tracking for the steel pipes exiting the furnace.

[0075] S3: After the steel pipe completes continuous rolling based on the continuous rolling mill, the dynamic tensile strength coefficient of the steel pipe is calculated based on the real-time obtained continuous rolling measurement length, and the tensile strength coefficient of the steel pipe is issued before the steel pipe enters the rolling operation of the tension reduction mill.

[0076] S4: After the steel pipe is rolled using a tension reduction mill, obtain the corresponding tension reduction measurement length.

[0077] in,

[0078] The online rolling length control method also establishes anomaly detection and handling mechanisms for steel pipe length control through the following anomaly detection settings:

[0079] First, after each steel pipe is rolled by the tension reduction mill, the post-calculated tensile strength coefficient of the steel pipe is determined based on the obtained corresponding tension reduction measurement length.

[0080] Then, the determined post-calculated tensile strength coefficients are compared laterally and analyzed longitudinally; the anomalies in the steel pipe are determined by combining the comparison of laterally and the analysis of longitudinally.

[0081] in,

[0082] The aforementioned lateral numerical comparison is accomplished by calculating the difference between the post-calculated tensile strength coefficient and the theoretical tensile strength coefficient for each current steel pipe.

[0083] The longitudinal numerical analysis is completed by statistically analyzing the overall distribution of all post-tension strength coefficients before the current steel pipe relative to the theoretical tension strength coefficient.

[0084] When the absolute value of the difference is greater than or equal to the set threshold, and the overall distribution of the post-tension strength coefficient relative to the theoretical tension strength coefficient is oscillating, it is determined that the current steel pipe length control is abnormal and a prompt is issued.

[0085] When the overall distribution of the post-tension strength coefficient relative to the theoretical tension strength coefficient shows a unidirectional and gradually increasing trend of difference, a risk warning is issued regarding the deterioration of the current steel pipe length control trend.

[0086] The specific steps are as follows:

[0087] SS1: When L1 receives the steel extraction signal from the heating furnace, it establishes queue-based tracking for the steel pipes exiting the furnace.

[0088] SS2: After the steel pipe completes continuous rolling based on the continuous rolling mill, the dynamic tensile strength coefficient of the steel pipe is calculated based on the real-time obtained continuous rolling measurement length, and the tensile strength coefficient of the steel pipe is issued before the steel pipe enters the rolling operation of the tension reduction mill.

[0089] SS3: After the steel pipe is rolled using a tension reduction mill, the corresponding tension reduction measurement length is obtained, and the post-calculated tensile strength coefficient is calculated based on the continuous rolling measurement length and the tension reduction measurement length.

[0090] SS4: Based on the comparison of transverse and longitudinal numerical values ​​using the post-calculated tensile strength coefficient, complete the anomaly determination of the steel pipe and provide an anomaly alert.

[0091] in,

[0092] The post-calculated tensile strength coefficient is determined according to the following formula:

[0093]

[0094] In the formula,

[0095] a and b: Both are regression coefficients.

[0096] in,

[0097] The theoretical tensile strength coefficient is determined according to the following formula:

[0098]

[0099] In the formula,

[0100] a and b: Both are regression coefficients.

[0101] in,

[0102] The anomaly determination can also be based on a comparison between the measured length of the tension reduction and the theoretical length of the tension reduction.

[0103] Working principle and process

[0104] The implementation of this technical solution consists of two parts. The first part is to determine the regression coefficients based on historical data; the second part is to perform dynamic length control and anomaly detection for each steel pipe based on real-time tracking of the rolling plan, using the determined regression coefficients. To understand this solution, the following sections will elaborate on the two parts separately (for further explanation, please refer to...). Figure 1 , 2 3):

[0105] I. On the determination of regression coefficients

[0106] Based on the following functional relationship,

[0107] (y: steel pipe tension reduction length; x: tension strength coefficient; L: continuous rolling length), based on historical continuous rolling measurement length, tension reduction measurement length, and actual tension strength coefficient, the regression coefficients a and b in the formula are determined; the regression adopts the least squares method; in specific regression, the sample space composed of historical data used for regression will also be classified according to three parameters: steel grade, finished product outer diameter, and finished product wall thickness, forming different categories based on the same steel grade, same finished product outer diameter, and same finished product wall thickness, and then regression coefficients corresponding to different categories will be derived. In specific control, regression coefficients matching the current rolling plan can be selected according to the actual rolling plan (because different control processes correspond to different stand pass types and standard tensions), and the system will be established when the rolling process parameters and target setpoints are issued to L2.

[0108] In the above formula, x is the tension strength coefficient, which adjusts the tension strength based on the standard tension. It uses a normalized value space of [-1, 1], theoretically following the following principle: a value of 0 indicates the use of standard tension. The smaller the value of x, the greater the tension between the frames. That is, when x < 0, the speed of the front frame is reduced based on the base speed corresponding to the standard tension, increasing the speed difference between the front and rear frames, thereby increasing the overall tension between the frames; when x > 0, the speed of the front frame is increased based on the base speed corresponding to the standard tension, decreasing the speed difference between the front and rear frames, thereby decreasing the overall tension between the frames. a and b are regression coefficients. Physically, a is the slope of the effect of the tension strength coefficient on the tension reduction extension length, and b is the extension coefficient of the tension reduction unit under standard tension conditions.

[0109] II. Dynamic Length Control and Anomaly Judgment for Each Steel Pipe

[0110] Tracking of each steel pipe begins when L2 receives the furnace extraction signal from L1. Upon receiving the extraction signal from L1, the current digitized information of the steel pipe is established and added to the rolling mill pipe tracking queue, with the current pipe status set to 1. Upon receiving the continuous rolling mill pipe rolling end signal, the continuous rolling measurement length information measured by the rolling mill is linked to the currently completed continuous rolling steel pipe in the rolling mill pipe tracking queue, and the steel pipe status is set to 2. Before the tension reduction mill receives the signal, the dynamic tension strength coefficient based on the current continuous rolling measurement length of the steel pipe is calculated and sent. The dynamic tension strength coefficient sent to L1 is used as the dynamic setting tension for the steel pipe to enter the tension reduction mill for rolling. The tensile strength coefficient is used to complete the rolling of the tension reduction mill. When the rolling end signal of the steel pipe of the tension reduction mill is obtained, the tension reduction measurement length measured by the rolling line and the post-calculated tensile strength coefficient information are linked to the current tension reduction rolling end steel pipe in the steel pipe tracking queue of the rolling line, and the status of the steel pipe is set to 3. Real-time numerical analysis is performed on all steel pipes updated to status setting 3, and anomaly judgment and handling are completed according to the analysis results. The data analysis here refers to: firstly, comparing the post-calculated tensile strength coefficient of each steel pipe with the theoretical tensile strength coefficient in real time. When the comparison value exceeds the set threshold, the distribution characteristics of the post-calculated tensile strength coefficients of all steel pipes before that steel pipe are judged.

[0111] When the absolute value of the difference is greater than or equal to the set threshold, and the overall distribution of the post-tension strength coefficient relative to the theoretical tension strength coefficient is oscillating, it is determined that the current steel pipe length control is abnormal and a prompt is made to remove it.

[0112] When the overall distribution of the post-calculated tensile strength coefficient relative to the theoretical tensile strength coefficient shows a unidirectional, gradually increasing trend of difference, a risk warning is issued regarding the deterioration of the current steel pipe length control trend. This anomaly judgment based on the post-calculated tensile strength coefficient can also be based on the determination of the tension reduction measured length and the tension reduction theoretical length; their essence is the same.

[0113] Example

[0114] Let's take a rolling batch of 20 steel pipes as an example. The initial information for rolling batch A is as follows:

[0115] Number of steel pipes Tracking status Finished product outer diameter Finished wall thickness Continuous rolling outer diameter Continuous rolling wall thickness Theoretical length of continuous rolling Zhang Jian Theoretical Length 20 0 73.03 5.6 151.5 6.75 31.702 81.620

[0116] in,

[0117] The units for variables such as billet diameter, finished product outer diameter, finished product wall thickness, continuous rolling outer diameter, and continuous rolling wall thickness are all mm; the units for fields such as feeding length, continuous rolling theoretical length, and tension reduction theoretical length are all m.

[0118] For ease of understanding, the formulas upon which the calculations are based are listed below:

[0119]

[0120]

[0121]

[0122] The dynamic tension strength coefficient in the above formula is the set value of the tension strength coefficient during the tension reduction rolling of steel pipe.

[0123] Once the first billet in the plan is extracted, rolling line tracking queue information can be established:

[0124]

[0125] In the above information, the tracking number is 1, and the current steel pipe tracking status is set to 1 after steel extraction. Therefore, the information such as continuous rolling measurement length, tension reduction measurement length, and post-calculated tensile strength coefficient are not obtained at this time, so they are all defaulted to 0.

[0126] When the first billet in the planned continuous rolling process is completed, it can be assumed that four billets have been extracted from the current rolling batch. The rolling line tracking queue information corresponding to the current rolling batch is as follows:

[0127]

[0128] At this point, in the rolling mill tracking queue information, the billet with tracking sequence number 1 has completed continuous rolling, the tracking status changes to 2, and the collected continuous rolling measurement length information is updated. Then, the dynamic tension coefficient is calculated. In this embodiment, the regression coefficients for the current specification are a = -0.098 and b = 2.523, therefore:

[0129] Dynamic tension coefficient:

[0130]

[0131] When the first billet leaves the continuous rolling mill but does not reach the tension reduction mill, the steel pipe length control system sends the corresponding dynamic tension coefficient of -0.738 to the L1 system for tension control.

[0132] When the first billet in the planned tension reduction rolling process is completed, the system acquires and updates the tension reduction measurement length and calculates the post-calculation tension coefficient information. Assuming there are four steel pipes in the tension reduction mill and continuous rolling mill, the tracking information is as follows:

[0133]

[0134] After all rolling processes of the current batch are completed, the tracking queue information is as follows:

[0135]

[0136] In the display screen of the steel pipe length control system, the steel pipe with tracking sequence number 3 has a tension reduction measurement length of 82.836m, and the calculated tension coefficient is -1.171, which deviates significantly from the theoretical tension coefficient, indicating an anomaly, which is highlighted in red on the screen. In addition to the table display of the steel pipe rolling tracking queue, the system also graphically displays the changing trends of the steel pipe tension reduction length and tension coefficient.

[0137] In the embodiment, the steel pipe length control system established according to this method uses dynamic tension coefficient for control, rejects the abnormal third steel pipe, and controls the steel pipe tension reduction length deviation within 0.3m with an average deviation of 0.1m, which can significantly improve the yield of hot-rolled steel pipe products.

[0138] This invention discloses an online control method for the hot rolling length of seamless steel pipes. First, it uses historical data to linearly regress the regression coefficients of the tension strength coefficient equation of the tension reduction mill. During regression, a classification regression is established according to steel grade and specification, forming regression coefficients matched with different steel grades and specifications. Then, during actual rolling, the regression coefficients matched with the current rolling plan are acquired along with other process parameters and setpoints. In actual production, a pipe-by-pipe tracking system is established from the start of the self-heating furnace steel extraction signal to the end of the pipe rolling process on the tension reduction mill. Based on the calculation and distribution of the dynamic tension strength coefficient for each pipe, the rolling length of each pipe is controlled. Simultaneously, anomaly detection and handling for pipe length control are established based on the post-calculated tension strength coefficient. In summary, this invention's online control method for the hot rolling length of seamless steel pipes improves the yield of hot-rolled products by establishing dynamic rolling length control for each pipe, and also adapts well to small-batch steel pipe production.

Claims

1. A method for online control of the hot rolling length of seamless steel pipes, characterized in that: First, a tracking system is established for each steel pipe from the start of the self-heating furnace steel extraction signal to the end of the steel pipe rolling process in the tension reduction mill. Then, for each steel pipe, before the tension reduction mill receives the signal after the continuous rolling mill has finished rolling, the dynamic tension strength coefficient based on the current continuous rolling measurement length of the steel pipe is calculated and issued. The issued dynamic tension strength coefficient is used as the set tension strength coefficient for the steel pipe entering the tension reduction mill for rolling, thus completing the rolling operation of the current steel pipe in the tension reduction mill. The calculation of the dynamic tensile strength coefficient based on the current continuous rolling measurement length of the steel pipe is specifically determined by the following formula: ， In the formula, a and b: Both are regression coefficients. The regression coefficients a and b are determined based on historical continuous rolling measurement lengths, historical tension reduction measurement lengths, historical actual tensile strength coefficients, and the following formula, using least squares regression: ， in: : Reduction in length of steel pipe; : Tensile strength coefficient; Continuous rolling length, The online rolling length control method also establishes anomaly detection and handling mechanisms for steel pipe length control through the following anomaly detection settings: First, after each steel pipe is rolled by the tension reduction mill, the post-calculated tensile strength coefficient of the steel pipe is determined based on the obtained corresponding tension reduction measurement length. Then, the determined post-calculated tensile strength coefficients are compared laterally and analyzed longitudinally; the anomalies in the steel pipe are determined by combining the comparison of laterally and the analysis of longitudinally.

2. The method for online control of the hot rolling length of seamless steel pipes according to claim 1, characterized in that: The historical data used for regression is used to classify the sample space according to three parameters: steel grade, finished product outer diameter, and finished product wall thickness. Different categories are formed based on the same steel grade, finished product outer diameter, and finished product wall thickness. Then, regression coefficients corresponding to different categories are obtained.

3. The method for online control of the hot rolling length of seamless steel pipes according to claim 1, characterized in that: The aforementioned lateral numerical comparison is accomplished by calculating the difference between the post-calculated tensile strength coefficient and the theoretical tensile strength coefficient for each current steel pipe. The longitudinal numerical analysis is completed by statistically analyzing the overall distribution of all post-tension strength coefficients before the current steel pipe relative to the theoretical tension strength coefficient. When the absolute value of the difference is greater than or equal to the set threshold, and the overall distribution of the post-tension strength coefficient relative to the theoretical tension strength coefficient is oscillating, it is determined that the current steel pipe length control is abnormal and a prompt is issued. When the overall distribution of the post-tension strength coefficient relative to the theoretical tension strength coefficient shows a unidirectional and gradually increasing trend of difference, a risk warning is issued regarding the deterioration of the current steel pipe length control trend.

4. The method for online control of the hot rolling length of seamless steel pipes according to claim 1, characterized in that: The post-calculated tensile strength coefficient is determined according to the following formula: ， In the formula, a and b: Both are regression coefficients.

5. The method for online control of the hot rolling length of seamless steel pipe according to claim 3, characterized in that: The theoretical tensile strength coefficient is determined according to the following formula: ， In the formula, a and b: Both are regression coefficients.

6. The method for online control of the hot rolling length of seamless steel pipes according to claim 2, characterized in that, The specific steps are as follows: S1: When issuing process parameters and set values ​​based on the current rolling plan to L2, determine the regression coefficients that match the current rolling plan together; S2: When L1 receives the steel extraction signal from the heating furnace, it establishes queue-based tracking for the steel pipes exiting the furnace. S3: After the steel pipe completes continuous rolling based on the continuous rolling mill, the dynamic tensile strength coefficient of the steel pipe is calculated based on the real-time obtained continuous rolling measurement length, and the tensile strength coefficient of the steel pipe is issued before the steel pipe enters the rolling operation of the tension reduction mill. S4: After the steel pipe is rolled using a tension reduction mill, obtain the corresponding tension reduction measurement length.

7. The method for online control of the hot rolling length of seamless steel pipes according to claim 1, characterized in that, The specific steps are as follows: SS1: When L1 receives the steel extraction signal from the heating furnace, it establishes queue-based tracking for the steel pipes exiting the furnace. SS2: After the steel pipe completes continuous rolling based on the continuous rolling mill, the dynamic tensile strength coefficient of the steel pipe is calculated based on the real-time obtained continuous rolling measurement length, and the tensile strength coefficient of the steel pipe is issued before the steel pipe enters the rolling operation of the tension reduction mill. SS3: After the steel pipe is rolled using a tension reduction mill, the corresponding tension reduction measurement length is obtained, and the post-calculated tensile strength coefficient is calculated based on the continuous rolling measurement length and the tension reduction measurement length. SS4: Based on the comparison of transverse and longitudinal numerical values ​​using the post-calculated tensile strength coefficient, complete the anomaly determination of the steel pipe and provide an anomaly alert.

8. The method for online control of the hot rolling length of seamless steel pipes according to claim 1, characterized in that: The anomaly determination can also be based on a comparison between the measured length of the tension reduction and the theoretical length of the tension reduction.

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