A method for accurately determining the position of a continuously cast mixed billet based on a surrounding magnetic field sensor

Abstract

This invention relates to a method for accurately determining the position of continuously cast mixed billets based on a surround magnetic field sensor. It enables the identification, correction, and precise determination of the initial position and cutting timing of continuously cast mixed billets (transition sections between different steel grades). It addresses the problem of cutting deviation in the mixed section caused by slippage and iron oxide scale interference in traditional positioning methods (incremental rotary encoders, infrared detection). It is applicable to the dynamic positioning of mixed billets before flame cutting in continuous casting machines of steel enterprises, providing data support for precise cutting of the mixed section, control of the consistency of the composition of subsequent rolled products, and optimization of the continuous casting process.

Description

Technical Field

[0001] This patent application belongs to the field of positioning and cutting control technology of mixed billets in continuous casting production. More specifically, it relates to a method for accurately determining the position of mixed billets in continuous casting based on a surrounding magnetic field sensor. Background Technology

[0002] In continuous casting production, a "mixed casting" mode (continuous casting of one steel grade with the next) is often used to improve production efficiency or switch steel grades. However, the mixed casting section has a transition zone for steel composition (usually 300-800mm in length), where the composition does not meet the requirements of downstream products and needs to be precisely cut off. If the positioning deviation of the mixed casting section is greater than 20mm, it can easily lead to "overcutting" (wasting qualified billets) or "undercutting" (unqualified billets flow into the rolling process, increasing the scrap rate of finished products by more than 30%), thus increasing production costs. Currently, the positioning methods for mixed casting billets are mainly divided into three categories, all of which have significant limitations, and "magnetic signal interference" and "position drift" are the core pain points. 1. Traditional incremental rotary encoder positioning method Using incremental rotary encoders (hereinafter referred to as encoders) on the continuous casting machine roller conveyor to record the billet displacement and calculate the position of the mixed-cast billet has three major drawbacks: (1) Significant error: Roller slippage (caused by high temperature deformation of the billet) and mechanical wear cause positioning error > 50 mm, which is far from meeting the requirement of ≤ 10 mm for the cutting accuracy of the mixed casting section of high-end steel grades (such as steel for automotive outer panels); (2) No ability to distinguish composition: It relies solely on displacement data and cannot identify changes in steel composition. If the length of the mixed casting section is abnormal (e.g., due to fluctuations in casting speed), it can easily lead to deviations in the cutting position. (3) Poor anti-interference: Vibration (roller operation) and electromagnetic radiation (motor equipment) at the continuous casting site will affect the encoder counting accuracy, with a bit error rate of >3%.

[0003] 2. Infrared temperature detection method Location is determined by capturing temperature differences in the casting section using an infrared camera (different steel grades have different thermal conductivity), but this method is highly susceptible to environmental interference. (1) Iron oxide scale obscuring: The absorption rate of infrared signals by the iron oxide scale (thickness 50~100μm) on the surface of the billet (85%~90%) is much higher than that of the billet body (60%~70%), which can easily obscure the temperature difference in the mixing section, resulting in a misjudgment rate of >25%; (2) Dust interference: The dust concentration at the continuous casting site is ≤15mg / m³, which will scatter infrared light, causing a temperature detection deviation of ±30℃, further amplifying the positioning error; (3) Response lag: Infrared image processing takes 0.5 to 1 second. If the casting speed is ≥1.5m / min, the billet has moved 12.5 to 18.75mm. The lag leads to cutting deviation.

[0004] 3. Manual marking and judgment methods Manually spraying markings (such as chalk or paint) onto the surface of the cast billet, and then using visual identification for positioning, has inherent defects: (1) Severe lag: Manual marking needs to be done 30 to 60 minutes after the billet exits the crystallizer (when the temperature drops below 400℃). The test results lag behind the production process by 1 to 2 hours. If the positioning of the mixing section is incorrect, a batch of unqualified billets has already been produced (the output of a single-strand continuous casting machine is about 180 tons per hour). (2) High subjectivity: The marking position depends on human experience, and the marking deviation between different operators can reach 30-50mm, resulting in insufficient consistency; (3) Low safety: High-temperature casting billets can easily cause burns, and dusty environments can harm the health of operators.

[0005] As the steel industry raises its quality requirements for high-end steel grades (such as pipeline steel and high-end automotive steel), the cutting accuracy of mixed-cast sections needs to be ≤8mm, making traditional positioning methods inadequate. The steel industry urgently needs a high-precision, interference-resistant, and real-time technology for determining the position of mixed-cast billets. Specific requirements are as follows: (1) Precision requirements: The positioning error of the concrete pouring section is ≤8mm, and the cutting position deviation is ≤10mm; (2) Real-time requirements: Magnetic signal detection response time ≤ 0.5 seconds, cutting timing calculation ≤ 1 second, to avoid deviation caused by billet movement; (3) Environmental adaptability requirements: withstand high temperature (ambient temperature ≤ 70℃), dust (concentration ≤ 20mg / m³), and electromagnetic interference at the continuous casting site; (4) Flexible adaptation requirements: It can adapt to billet specifications (width 800~2200mm, thickness 150~300mm) and common steel grades (low alloy steel, carbon steel, stainless steel) without stopping the machine to replace the sensor; (5) Linkage requirements: It can communicate with the PLC of the flame cutting machine in real time to realize the "positioning-cutting" closed-loop control.

[0006] In summary, to address the shortcomings of traditional positioning methods, such as "lack of component differentiation capability, poor anti-interference, and low accuracy," developing a mixed-cast billet positioning technology based on a surround magnetic field sensor and combining "magnetic permeability difference identification + position correction algorithm" is a key path to solve existing pain points and adapt to the production of high-end steel grades. Summary of the Invention

[0007] To address the problems of "inability to distinguish composition, large positioning error, and weak anti-interference" in the positioning of mixed casting billets in existing continuous casting, this invention provides a method for accurately determining the position of mixed casting billets based on a surround magnetic field sensor. Through a collaborative scheme of "surround magnetic field sensor deployment (capturing differences in magnetic permeability of steel grades) + magnetic signal feature recognition (distinguishing between mixed casting transition sections) + position correction algorithm (optimizing the cutting range according to the 80 / 20 principle) + PLC-linked cutting", the method achieves non-contact, high-precision, and real-time determination of the initial position identification, correction, and cutting timing of the mixed casting billet, providing support for precise cutting of the mixed casting section.

[0008] To solve the above problems, the technical solution adopted by the present invention is as follows: A method for accurately determining the position of continuously cast mixed billets based on a surround magnetic field sensor includes the following steps: S1. System deployment and parameter design of the surround magnetic field sensor: At a distance of 12 to 15m from the zero point of the flame cutting machine, the surround magnetic field sensor and the matching incremental rotary encoder are deployed to ensure that there are no blind spots covering the surface of the billet (including the edges and corners). At the same time, a cooling and dustproof device is deployed on the outside of the surround magnetic field sensor. S2. Magnetic signal acquisition and feature recognition: Based on data from a surround magnetic field sensor, a three-level model was developed: "synchronous acquisition and filtering of magnetic signals - magnetic signal feature recognition of the concrete pouring section - initial position determination," to accurately identify the concrete pouring section. S3. Correction of the position of the mixed casting billet and calculation of the cutting timing: Based on the "80 / 20" principle, the cutting range is optimized, and the cutting timing is calculated by combining the fixed distance between the surrounding magnetic field sensor and the cutting machine. S4. After the model completes position correction and time calculation, it sends the cutting time of the mixed casting blank head and tail to the flame cutting machine PLC, which are recorded as Now_Start and Now_End respectively. The flame cutting machine PLC then completes the cutting of the mixed casting blank according to the time sent by the system.

[0009] Furthermore, in S1, the surrounding magnetic field sensor includes three high-precision magnetic permeability detection sensors evenly distributed along the circumference of the billet, and each of the three magnetic field sensors is equipped with a high-temperature resistant protective cover; the cooling and dust prevention device includes a matching circulating water cooling unit and a high-pressure air dust prevention unit.

[0010] Furthermore, the three high-precision magnetic permeability detection sensors have the following permeability detection ranges: 100~1000μH / m; detection accuracy: ±1μH / m; response frequency: ≥100Hz; environmental adaptability: operating temperature -30~80℃, protection level IP68.

[0011] Furthermore, in S2, the filtering algorithm involved in "synchronous acquisition and filtering of magnetic signals" is a combination of "Kalman filtering + moving average filtering" to remove interference signals.

[0012] Furthermore, in S2, "Magnetic signal feature identification of the casting section" includes the following: S21. Stable Section Judgment: When the fluctuation of the filtered magnetic permeability data is ≤5% (e.g., Q355B is stable at 350±17.5μH / m), and the duration is ≥0.5 seconds, it is judged as "single steel grade stable section"; S22. Transition Section Judgment: When the magnetic permeability data fluctuates by more than 5% (e.g., from 350μH / m to 280μH / m, a fluctuation of 20%), and the duration is ≥0.1 seconds, it is judged as a "mixing transition section". S23. Initial position determined: ① The initial start position of the mixed-cast billet is recorded as A_Start: When the magnetic signal switches from the "stable section" to the "transition section", the matching incremental rotary encoder feeds back the position of the billet from the meniscus of the crystallizer; ② The initial end position of the mixed casting billet is recorded as A_End: When the magnetic signal switches from the "transition section" back to the "stable section", the matching incremental rotary encoder feeds back the position of the casting billet from the meniscus of the crystallizer, and records the time Now0 at this moment. ③ The initial length of the mixed-cast billet L = |A_End - A_Start| (e.g., A_Start = 15000mm, A_End = 23000mm, then L = 8000mm).

[0013] Furthermore, S3 specifically includes the following steps: S31. Calculation of the correction position for the mixed-cast billet; S32, Calculation of distance to cutting position; S33, Calculation of cutting timing.

[0014] Furthermore, in S31, the "calculation of the correction position for the mixed-cast billet" specifically refers to... ① The starting position of the corrected mixed-cast billet is recorded as A'_Start, A'_Start = A_Start + 20%×L, which is used to remove the front 20% transition zone and reduce the influence of the mixed-cast billet; ② The corrected end position of the mixed-cast billet is recorded as A'_End, where A'_End = A_End - 20%×L, to remove the 20% transition zone at the rear end and reduce the impact of the mixed-cast billet; ③ The effective length of the corrected concrete pouring section is recorded as L', where L' = A'_End - A'_Start = 60% × L (e.g., if L = 8000mm, then L' = 5600mm).

[0015] Furthermore, in S32, the distance L0 from the surround magnetic field sensor to the zero point of the cutting machine is a fixed value, and the "cutting position distance calculation" is specifically as follows: 1) The distance from the head of the mixed-cast billet to the zero point of the flame cutting machine after correction is L_Start = L0 - (A_End - A'_Start) = L0 - L×(100% - 20%) (Derivation: A_End - A'_Start = L - 20% L = 80% L, therefore L_Start = L0 - 0.8L). 2) The distance from the tail of the cast billet to the zero point of the flame cutting machine after correction is L_End = L0 - (A_End - A'_End) = L0 - L×20% (Derivation: A_End - A'_End = 20% L, therefore L_End = L0 - 0.2L); Example: L0=14000mm, L=8000mm, then L_Start=14000 - 0.8×8000=7600mm, L_End=14000 - 0.2×8000=12400mm.

[0016] Furthermore, in S33, based on the continuous casting speed V, in m / min, the "cutting timing calculation" is specifically as follows: 1) The time for the mixed casting billet head to reach the zero point of the flame cutting machine after correction is t_Start = L_Start / (V×1000)×60, unit: seconds, continuous casting speed V is converted to mm / s; 2) The time for the tail of the mixed casting billet to reach the zero point of the flame cutting machine after correction is t_End = L_End / (V×1000)×60, unit: seconds, and the continuous casting speed V is converted to mm / s; Example: V = 1.2 m / min = 20 mm / s, then t_Start = 7600 / 20 = 380 seconds = 6 minutes 20 seconds, t_End = 12400 / 20 = 620 seconds = 10 minutes 20 seconds.

[0017] Then, calculate the moment when the head of the cast billet reaches the zero point of the flame cutting machine: Now_Start = Now0 + t_Start The moment when the tail of the cast billet reaches the zero point of the flame cutter: Now_End = Now0 + t_End Now0 represents the current moment.

[0018] Due to the adoption of the above technical solution, the beneficial effects achieved by this invention are: At a distance of 12-15m from the zero point of the flame cutting machine (when the surface temperature of the billet drops to 700-800℃, completing the transformation from austenite to ferrite / pearlite and acquiring stable magnetism), a surrounding magnetic field sensor is deployed. By detecting the difference in magnetic permeability of different steel grades through the sensor, the "stable-fluctuating-stable" magnetic signal characteristics of the mixing section are identified, and the initial position of the mixed billet (A_Start, A_End) is determined. The positioning range is corrected based on the "80 / 20" principle, and the cutting timing is calculated in combination with the continuous casting speed. Finally, the data is transmitted to the PLC of the flame cutting machine to achieve precise cutting.

[0019] Compared with existing technologies, it has the following significant advantages: 1. High positioning accuracy: Through "magnetic permeability difference recognition + '80 / 20' correction algorithm", the positioning error of the mixed casting billet is ≤8mm and the cutting position deviation is ≤10mm, which is more than 6 times higher than the traditional encoder positioning (error >50mm). The qualified rate of the mixed casting section cutting is increased from 70% to 99.8%. 2. High real-time performance: The response frequency of the surround magnetic field sensor is ≥100Hz, and the magnetic signal processing and cutting time calculation is ≤1 second. There is no lag, which can avoid the cutting deviation caused by the movement of the billet (when the casting speed is 1.5m / min, the billet only moves 25mm in 1 second, which can be fully compensated after correction). 3. Outstanding anti-interference capability: The "cooling and dustproof device + combined filtering algorithm" can effectively resist high temperature (ambient environment ≤70℃), dust (≤20mg / m³), and electromagnetic interference. The magnetic permeability detection error is ≤1μH / m, and the effective data rate is >99.5%, which is a significant improvement over infrared detection (false judgment rate >25%). 4. Low cost and flexible adaptation: The cost of a single unit of the surround magnetic field sensor is less than 20,000 yuan (only 30% of that of the infrared temperature detection system), making it easy to promote on a large scale; it is compatible with billet specifications (width 800-2200mm, thickness 150-300mm) and common steel grades. When switching, only the "steel grade-permeability" library needs to be updated (time taken < 5 minutes), without downtime. 5. Intelligent linkage: The detection data communicates with the flame cutting machine PLC in real time to realize the "positioning-cutting" closed-loop control, reducing manual intervention (it can replace 2-3 manual marking operators). At the same time, the data traceability function provides support for the optimization of continuous casting process (such as adjusting the cooling water volume of the crystallizer by the fluctuation of the mixing section length), reducing production costs by 15% to 20%. Attached Figure Description

[0020] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the embodiments.

[0022] A method for accurately determining the position of continuously cast mixed billets based on a surround magnetic field sensor, such as... Figure 1 The process shown includes the following steps: S1. System deployment and parameter design of the surround magnetic field sensor: At a distance of 12 to 15m from the zero point of the flame cutting machine, the surround magnetic field sensor and the matching incremental rotary encoder are deployed to ensure that there are no blind spots covering the surface of the billet (including the edges and corners). At the same time, a cooling and dustproof device is deployed on the outside of the surround magnetic field sensor. S2. Magnetic signal acquisition and feature recognition: Based on data from a surround magnetic field sensor, a three-level model was developed: "synchronous acquisition and filtering of magnetic signals - magnetic signal feature recognition of the concrete pouring section - initial position determination," to accurately identify the concrete pouring section. S3. Correction of the position of the mixed casting billet and calculation of the cutting timing: Based on the "80 / 20" principle, the cutting range is optimized, and the cutting timing is calculated by combining the fixed distance between the surrounding magnetic field sensor and the cutting machine. S4. After the model completes position correction and time calculation, it sends the cutting time of the mixed casting blank head and tail to the flame cutting machine PLC, which are recorded as Now_Start and Now_End respectively. The flame cutting machine PLC then completes the cutting of the mixed casting blank according to the time sent by the system.

[0023] Furthermore, in S1, the surrounding magnetic field sensor includes three high-precision magnetic permeability detection sensors evenly distributed along the circumference of the billet, and each of the three magnetic field sensors is equipped with a high-temperature resistant protective cover; the cooling and dust prevention device includes a matching circulating water cooling unit and a high-pressure air dust prevention unit.

[0024] Furthermore, the three high-precision magnetic permeability detection sensors have the following permeability detection ranges: 100~1000μH / m; detection accuracy: ±1μH / m; response frequency: ≥100Hz; environmental adaptability: operating temperature -30~80℃, protection level IP68.

[0025] Furthermore, in S2, the filtering algorithm involved in "synchronous acquisition and filtering of magnetic signals" is a combination of "Kalman filtering + moving average filtering" to remove interference signals.

[0026] Furthermore, in S2, "Magnetic signal feature identification of the casting section" includes the following: S21. Stable Section Judgment: When the fluctuation of the filtered magnetic permeability data is ≤5% (e.g., Q355B is stable at 350±17.5μH / m), and the duration is ≥0.5 seconds, it is judged as "single steel grade stable section"; S22. Transition Section Judgment: When the magnetic permeability data fluctuates by more than 5% (e.g., from 350μH / m to 280μH / m, a fluctuation of 20%), and the duration is ≥0.1 seconds, it is judged as a "mixing transition section". S23. Initial position determined: ① The initial start position of the mixed-cast billet is recorded as A_Start: When the magnetic signal switches from the "stable section" to the "transition section", the matching incremental rotary encoder feeds back the position of the billet from the meniscus of the crystallizer; ② The initial end position of the mixed casting billet is recorded as A_End: When the magnetic signal switches from the "transition section" back to the "stable section", the matching incremental rotary encoder feeds back the position of the casting billet from the meniscus of the crystallizer, and records the time Now0 at this moment. The core function of the incremental rotary encoder is to provide accurate position data. Specifically, at the critical moment when the surrounding magnetic field sensor detects the switching of the magnetic signal (stable section → transition section, transition section → stable section), it feeds back the specific position of the billet from the meniscus of the crystallizer, which is used to determine the initial start position (A_Start) and initial end position (A_End) of the mixed billet. At the same time, it can assist in completing the sensor positioning calibration and supplement the position data support. The core function of the surround magnetic field sensor is to identify the characteristics of the mixed casting section and the trigger positioning time: it collects the magnetic permeability signal of the billet, removes interference through a combined filtering algorithm, and distinguishes between the "single steel grade stable section" and the "mixed casting transition section" by the magnetic permeability fluctuation characteristics, and locks the start and end switching nodes of the mixed casting section; at the same time, it is adapted to the high temperature and dust environment of the continuous casting site, providing the core trigger basis for subsequent position correction and cutting timing calculation.

[0027] ③ The initial length of the mixed-cast billet L = |A_End - A_Start| (e.g., A_Start = 15000mm, A_End = 23000mm, then L = 8000mm).

[0028] Furthermore, S3 specifically includes the following steps: S31. Calculation of the correction position for the mixed-cast billet; S32, Calculation of distance to cutting position; S33, Calculation of cutting timing.

[0029] Furthermore, in S31, the "calculation of the correction position for the mixed-cast billet" specifically refers to... ① The starting position of the corrected mixed-cast billet is recorded as A'_Start, A'_Start = A_Start + 20%×L, which is used to remove the front 20% transition zone and reduce the influence of the mixed-cast billet; ② The corrected end position of the mixed-cast billet is recorded as A'_End, where A'_End = A_End - 20%×L, to remove the 20% transition zone at the rear end and reduce the impact of the mixed-cast billet; ③ The effective length of the corrected concrete pouring section is recorded as L', where L' = A'_End - A'_Start = 60% × L (e.g., if L = 8000mm, then L' = 5600mm).

[0030] Furthermore, in S32, the distance L0 from the surround magnetic field sensor to the zero point of the cutting machine is a fixed value, and the "cutting position distance calculation" is specifically as follows: 1) The distance from the head of the mixed-cast billet to the zero point of the flame cutting machine after correction is L_Start = L0 - (A_End - A'_Start) = L0 - L×(100% - 20%) (Derivation: A_End - A'_Start = L - 20% L = 80% L, therefore L_Start = L0 - 0.8L). 2) The distance from the tail of the cast billet to the zero point of the flame cutting machine after correction is L_End = L0 - (A_End - A'_End) = L0 - L×20% (Derivation: A_End - A'_End = 20% L, therefore L_End = L0 - 0.2L); Example: L0=14000mm, L=8000mm, then L_Start=14000 - 0.8×8000=7600mm, L_End=14000 - 0.2×8000=12400mm.

[0031] Furthermore, in S33, based on the continuous casting speed V, in m / min, the "cutting timing calculation" is specifically as follows: 1) The time for the mixed casting billet head to reach the zero point of the flame cutting machine after correction is t_Start = L_Start / (V×1000)×60, unit: seconds, continuous casting speed V is converted to mm / s; 2) The time for the tail of the mixed casting billet to reach the zero point of the flame cutting machine after correction is t_End = L_End / (V×1000)×60, unit: seconds, and the continuous casting speed V is converted to mm / s; Example: V = 1.2 m / min = 20 mm / s, then t_Start = 7600 / 20 = 380 seconds = 6 minutes 20 seconds, t_End = 12400 / 20 = 620 seconds = 10 minutes 20 seconds.

[0032] Then, calculate the moment when the head of the cast billet reaches the zero point of the flame cutting machine: Now_Start = Now0 + t_Start The moment when the tail of the cast billet reaches the zero point of the flame cutter: Now_End = Now0 + t_End Now0 represents the current moment.

[0033] The specific implementation method is as follows: Based on an application case of a 1800mm slab continuous casting machine at a steel plant (producing a mixture of Q355B low-alloy steel and SPHC low-carbon steel), the implementation steps are explained in detail: Step 1: System Deployment and Calibration (1) Installation of cooling and dust prevention device: An integrated device of "circulating water cooling + high-pressure air dust prevention" is deployed on the roller support at a distance of 14m from the zero point of the flame cutting machine (L0=14000mm). 1) Circulating water cooling unit: Deionized water flow rate 2.5L / min, inlet water temperature 28℃, sensor temperature stabilizes at 45℃ after cooling; 2) High-pressure air dust removal unit: pressure 0.5MPa, flow rate 5m³ / h, 6 nozzles distributed around the sensor circumference, dust removal effect reaches 98%.

[0034] (2) Installation and calibration of the surround magnetic field sensor: 1) Sensor selection: Select MTS-800 high-precision magnetic field sensor, parameters: magnetic permeability range 100~1000μH / m, accuracy ±1μH / m, response frequency 100Hz, protection IP68, Profinet interface; 2) Installation location: 3 sensors are distributed along the circumference of the billet (with an included angle of 120°), with the inner ring 12cm away from the surface of the billet, and a stainless steel protective cover (temperature resistant to 120℃) is installed on the outside. 3) Calibration: ① Establish a "steel grade - magnetic permeability" library: Q355B (magnetic permeability of 350μH / m at 750℃), SPHC (magnetic permeability of 280μH / m at 750℃); ② Position calibration: Using a 20m standard casting billet, the incremental rotary encoder displays 20000mm, and the sensor detects the position at 20001mm. After correction using the least squares method, the positioning error is 1.5mm.

[0035] Step 2: Magnetic signal acquisition and feature recognition (1) Magnetic signal acquisition: continuous casting speed V=1.2m / min (20mm / s), billet temperature 750℃, sensor acquires 1 set of magnetic permeability data every 0.01 seconds, and synchronously records the position of incremental rotary encoder; When the magnetic permeability changes from 350μH / m (fluctuation ≤5%, stable section) to 320~340μH / m (fluctuation >5%, transition section), the incremental rotary encoder feedback position A_Start = 15000mm; When the magnetic permeability stabilizes at 280μH / m (fluctuation ≤5%, stable segment), the incremental rotary encoder feedback position A_End = 23000mm, and the computer records the current time 10:00:00. The initial length of the mixed-cast blank is L = |23000-15000| = 8000 mm.

[0036] (2) Magnetic signal filtering: The electromagnetic interference of the motor is eliminated by Kalman filtering (the magnetic permeability changes by ±10μH / m before filtering and ±2μH / m after filtering). After moving average filtering (10-point average), the smoothness of the magnetic permeability curve in the transition section is improved by 90%, and there is no random noise.

[0037] Step 3: Position Correction and Cutting Timing Calculation (1) Correction position calculation: A'_Start=15000 + 20%×8000=16600mm; A'_End=23000 - 20%×8000=21400mm; The corrected effective length L' = 21400 - 16600 = 4800 mm.

[0038] (2) Calculation of distance to cutting position: L_Start=14000 - 0.8×8000=7600mm; L_End=14000 - 0.2×8000=12400mm.

[0039] (3) Calculation of cutting timing: t_Start = 7600mm / 20mm / s = 380 seconds = 6 minutes 20 seconds; t_End=12400mm / 20mm / s=620 seconds=10 minutes 20 seconds (i.e. 10:16:37).

[0040] Therefore, the time from the start of the cast billet to the zero point of the flame cutting machine is: Now_Start = 10:00:00 + 6 minutes 20 seconds = 10:06:20 The time from the end of the cast billet to the zero point of the flame cutting machine is: Now_End = 10:00:00 + 10 minutes 20 seconds = 10:10:20 Step 4: Cutting with a linked flame cutting machine The model transmits Now_Start=10:06:20 and Now_End=10:10:20 to the PLC of the flame cutting machine. The PLC completes the cutting of the mixed casting blank according to the transmission time.

Claims

1. A method for accurately determining the position of continuously cast mixed billets based on a surround magnetic field sensor, characterized in that, Includes the following steps: S1. System deployment and parameter design of the surround magnetic field sensor: At a distance of 12 to 15m from the zero point of the flame cutting machine, the surround magnetic field sensor and the matching incremental rotary encoder are deployed to ensure that there are no blind spots covering the surface of the billet. At the same time, a cooling and dustproof device is deployed on the outside of the surround magnetic field sensor. S2. Magnetic signal acquisition and feature recognition: Based on data from a surround magnetic field sensor, a three-level model was developed: "synchronous magnetic signal acquisition and filtering - magnetic signal feature recognition of the concrete pouring section - initial position determination," to accurately identify the concrete pouring section. S3. Correction of the position of the mixed casting billet and calculation of the cutting timing: Based on the "80 / 20" principle, the cutting range is optimized, and the cutting timing is calculated by combining the fixed distance between the surrounding magnetic field sensor and the cutting machine. S4. After the model completes position correction and time calculation, it sends the cutting time of the mixed casting blank head and tail to the flame cutting machine PLC. The flame cutting machine PLC then completes the cutting of the mixed casting blank according to the time sent by the system.

2. The method for accurately determining the position of continuously cast mixed billets based on a surround magnetic field sensor according to claim 1, characterized in that, In S1, the surrounding magnetic field sensor includes three high-precision magnetic permeability detection sensors evenly distributed along the circumference of the billet. All three magnetic field sensors are equipped with high-temperature resistant protective covers. The cooling and dust prevention device includes a matching circulating water cooling unit and a high-pressure air dust prevention unit.

3. The method for accurately determining the position of a continuously cast mixed billet based on a surrounding magnetic field sensor according to claim 2, characterized in that, The three high-precision magnetic permeability sensors have a magnetic permeability detection range of 100~1000μH / m, a detection accuracy of ±1μH / m, a response frequency of ≥100Hz, and an environmental adaptability of -30~80℃ and an IP68 protection rating.

4. The method for accurately determining the position of continuously cast mixed billets based on a surround magnetic field sensor according to claim 1, characterized in that, In S2, the filtering algorithm involved in "synchronous acquisition and filtering of magnetic signals" is a combination of "Kalman filtering + moving average filtering" to remove interference signals.

5. The method for accurately determining the position of continuously cast mixed billets based on a surrounding magnetic field sensor according to claim 1, characterized in that, In S2, "Magnetic Signal Feature Identification of the Casting Section" includes the following content. S21. Stable Section Judgment: When the fluctuation of the filtered magnetic permeability data is ≤5% and the duration is ≥0.5 seconds, it is judged as "single steel grade stable section"; S22. Transition Section Judgment: When the permeability data fluctuation is >5% and the duration is ≥0.1 seconds, it is judged as "casting transition section"; S23. Initial position determined: ① The initial start position of the mixed casting billet is recorded as A_Start: When the magnetic signal switches from the "stable section" to the "transition section", the matching incremental rotary encoder feeds back the position of the casting billet from the meniscus of the crystallizer; ② The initial end position of the mixed casting billet is recorded as A_End: When the magnetic signal switches from the "transition section" back to the "stable section", the matching incremental rotary encoder feeds back the position of the casting billet from the meniscus of the crystallizer, and records the time Now0 at this time. ③ The initial length of the mixed-cast blank is L = |A_End - A_Start|.

6. A method for accurately determining the position of a continuously cast mixed billet based on a surround magnetic field sensor, as described in any one of claims 1-5, characterized in that, S3 specifically includes the following steps: S31. Calculation of the correction position for the mixed-cast billet; S32, Calculation of distance to cutting position; S33, Calculation of cutting timing.

7. The method for accurately determining the position of a continuously cast mixed billet based on a surround magnetic field sensor according to claim 6, characterized in that, In S31, the "Calculation of Correction Position for Mixed Casting Billet" specifically refers to... ① The starting position of the corrected mixed-cast billet is recorded as A'_Start, A'_Start = A_Start + 20%×L, which is used to remove the front 20% transition zone and reduce the influence of the mixed-cast billet; ② The corrected end position of the mixed-cast billet is recorded as A'_End, where A'_End = A_End - 20%×L, to remove the 20% transition zone at the rear end and reduce the impact of the mixed-cast billet; ③ The effective length of the corrected concrete pouring section is recorded as L', where L' = A'_End - A'_Start = 60% × L.

8. The method for accurately determining the position of continuously cast mixed billets based on a surround magnetic field sensor according to claim 6, characterized in that, In S32, the distance L0 from the surround magnetic field sensor to the zero point of the cutting machine is a fixed value. The "cutting position distance calculation" is specifically... 1) The distance from the head of the mixed-cast billet to the zero point of the flame cutting machine after correction is L_Start = L0 - (A_End - A'_Start) = L0 - L×(100% - 20%); 2) The distance from the tail of the cast billet to the zero point of the flame cutting machine after correction is L_End = L0 - (A_End - A'_End) = L0 - L×20%.

9. A method for accurately determining the position of a continuously cast mixed billet based on a surrounding magnetic field sensor, as described in claim 6, is characterized in that... In S33, based on the continuous casting speed V, in m / min, the "cutting timing calculation" is specifically as follows: 1) The time for the mixed casting billet head to reach the zero point of the flame cutting machine after correction is t_Start = L_Start / (V×1000)×60, unit: seconds, continuous casting speed V is converted to mm / s; 2) The time for the tail of the mixed casting billet to reach the zero point of the flame cutting machine after correction is t_End = L_End / (V×1000)×60, unit: seconds, and the continuous casting speed V is converted to mm / s; Then, calculate the moment when the head of the cast billet reaches the zero point of the flame cutting machine: Now_Start = Now0 + t_Start The moment when the tail of the cast billet reaches the zero point of the flame cutter: Now_End = Now0 + t_End Now0 represents the current moment.

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