A 16-meter billet straight rolling low-energy electromagnetic heat supplement method

Abstract

The present application relates to the technical field of electromagnetic heat supplement of straight rolling of bar billet, and particularly discloses a 16-meter billet straight rolling low-energy electromagnetic heat supplement method, four independent electromagnetic coils are installed on the bar, and each electromagnetic coil is connected with an inverter; a single-branch heating mode and an overall heating mode are designed for the billet heat supplement system, and the head and tail of the billet are heated separately according to the billet incoming temperature; the billet heat supplement system is designed with ten heating temperature sections and equipped with different heating speeds, after setting, the given voltage of the ten temperature sections is automatically selected according to the different billet incoming temperature, so that the temperature after the electromagnetic heat supplement furnace is locked within a limited range; the overall heating or single-branch start-stop can be freely selected according to different steel grades; the head heating and tail heating as well as the priority stop function are realized according to the temperature difference between the head and tail of the billet; the electromagnetic heat supplement of 16-meter billet straight rolling is realized, the temperature difference is effectively controlled, and the energy consumption is reduced.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic heating technology for direct rolling of bar billets, specifically to a low-energy electromagnetic heating method for direct rolling of 16-meter billets. Background Technology

[0002] In steel production, direct billet rolling technology in bar and wire rod production lines effectively reduces energy consumption and improves efficiency. Electromagnetic heating technology is used to precisely control billet temperature, ensuring rolling quality and reducing energy consumption. Electromagnetic heating heats the surface of the billet through electromagnetic induction, bringing it to the required rolling temperature. Compared to traditional heating methods, electromagnetic heating offers advantages such as rapid heating, precise temperature control, and energy efficiency. The direct billet rolling process includes billet preparation, electromagnetic heating, direct rolling, and cooling. Combining direct billet rolling with low-energy electromagnetic heating technology effectively reduces energy consumption, improves production efficiency and product quality, and represents an important development direction for the steel industry.

[0003] The 16-meter billet direct rolling length is relatively large. Currently, while 12-meter billet direct rolling technology has been implemented in China, there is no electromagnetic heating technology for 16-meter billets. Existing electromagnetic heating methods result in uneven billet temperatures, with a temperature difference of approximately 50 degrees Celsius between the beginning and end. Power consumption is also high, reaching around 10 kWh. Uneven incoming temperature of individual billets leads to a large temperature difference of approximately 30 degrees Celsius after heating. Therefore, a low-energy-consumption electromagnetic heating method for 16-meter billet direct rolling is needed to address the gap in existing 16-meter billet direct rolling electromagnetic heating technology and the high energy consumption caused by large temperature differences in electromagnetic heating for other billet sizes. Summary of the Invention

[0004] To address the problems existing in the prior art, the purpose of this invention is to provide a low-energy electromagnetic heating method for direct rolling of 16-meter steel billets.

[0005] The technical solution adopted by this invention to solve its technical problem is: a low-energy electromagnetic heating method for direct rolling of 16-meter steel billets, comprising the following steps:

[0006] S1. The bar wire is equipped with four independently controlled electromagnetic coils, and each electromagnetic coil is connected to an inverter.

[0007] S2. The billet heating system is designed with single-branch heating mode and overall heating mode, and heats the head and tail of the billet separately according to the incoming temperature of the billet.

[0008] S3. The billet heating system is designed with 10 heating temperature segments and different heating rates. After being set, it automatically selects the given voltage for each of the 10 temperature segments according to the different incoming temperatures of the billet, so that the temperature after passing through the electromagnetic heating furnace is locked within a limited range.

[0009] Specifically, in step S1, the continuously cast billet upstream of the bar production line is directly and quickly fed to the induction heating device by the roller conveyor. The induction heating device automatically compensates the billet temperature according to the incoming billet temperature. After the billet reaches the required temperature, it is transported to the downstream rolling mill for rolling. The 16-meter-long hot-delivered billet has a limited surface temperature of ≥830℃ at the head of the billet. When the surface temperature of the billet head is 830℃, the surface temperature of the billet tail is not lower than 890℃.

[0010] Specifically, in step S1, the heating power of the electromagnetic coil is 1800KW, and the four electromagnetic coils are controlled by two sets of rectifier transformers. The heating power of each electromagnetic coil and the target temperature of the billet are controlled in a closed loop. If one set of electromagnetic coils fails, it is discarded and the remaining three sets are used. The heating speed of the electromagnetic coils is ≥320t / h, the reheating temperature is 100℃, and the heating time is ≤36s. The running speed of the electromagnetic reheating roller is ≥0.44m / s, and the maximum speed of the induction heating roller is ≥1.5m / s.

[0011] Specifically, the billet heating system in step S2 is equipped with a power control module, a frequency converter control module, and a production line operation module. The power control module includes a rectifier cabinet, inverter 1, inverter 2, inverter 3, and inverter 4. The frequency converter control module includes frequency converter 1, frequency converter 2, frequency converter 3, and frequency converter 4. The production line operation module includes a parameter setting section and a button control section.

[0012] Specifically, in step S2, the overall heating mode is such that when the segmented temperature is not selected before input, the electromagnetic coil will output voltage according to the four set values ​​of inverter 1, inverter 2, inverter 3, and inverter 4 set by the billet heating system, and the roller conveyor will run according to the set value of roller conveyor heating speed during heating.

[0013] When the single-branch heating mode is selected before segmented temperature input and head heating is selected, if the temperature acquisition value does not meet the temperature range set by the head parameters, the electromagnetic coil will output voltage according to the four set values ​​of inverter 1, inverter 2, inverter 3, and inverter 4. During heating, the roller conveyor will run according to the roller conveyor heating speed set value.

[0014] Specifically, the setting parameters include the head heating time, furnace front deceleration time, furnace rear deceleration time, temperature acquisition time, and speed-up priority shutdown time. The head heating time is set after the No. 4 heat detector detects a signal and the speed is increased to the set value for the roller conveyor speed after a delay when the head heating mode is selected, until the roller conveyor speed is reached. The furnace front deceleration time is set after the No. 1 heat detector detects a signal and the speed is decreased to the set value for the roller conveyor heating speed after a delay when the billet exits the straightener. The furnace rear deceleration time is set after the No. 4 heat detector detects a signal and the speed is decreased to the set value for the roller conveyor heating speed. The set value is set to reduce the speed of the roller conveyor after the furnace, and reduce the speed to the set value of the roller conveyor heating speed; Temperature acquisition time: the timer starts after the billet exits the straightener No. 1 heat detector receives a signal, and the average value of the maximum values ​​of No. 1 pyrometer and No. 2 pyrometer is taken as the acquisition value within the set value time; Speed-up priority shutdown time: when the billet exits the furnace and No. 4 heat detector receives a signal, and after the head heating time set value is delayed, the roller conveyor starts to speed up. After speeding up, the speed-up priority shutdown time set value is delayed, and the selected inverter will be shut down first. Other unselected inverters will be shut down after the billet has completely exited the furnace.

[0015] Specifically, the billet heating system in step S3 is designed with 10 heating temperature segments and different heating rates. According to the production design, the incoming material temperature will not be lower than 830℃ and will not be higher than 970℃. The temperature range of 830℃ to 970℃ is divided into 10 temperature segments, with each segment lasting 14℃. The corresponding heating rate is 0.41m / s to 0.5m / s. The heating rate changes every 0.01m / s, which corresponds to a temperature segment. The heating time is automatically adjusted according to the incoming material temperature.

[0016] Specifically, when the incoming material temperature is between 820℃ and 834℃, the heating voltage given by the four electromagnetic coils is all 1300V, and the heating rate is 0.41m / s. When the incoming material temperature is between 956℃ and 970℃, the heating voltage given by the four electromagnetic coils will automatically adjust to 1200V, 1150V, 1100V, and 950V, and the heating rate will automatically become 0.5m / s.

[0017] The present invention has the following beneficial effects:

[0018] The invention presents a low-energy electromagnetic heating method for direct rolling of 16-meter steel billets. Depending on the type of steel being produced, it allows for the selection of overall heating or single-piece start / stop. It achieves head and tail heating and priority stop functions based on the temperature difference between the head and tail of the billet. Ten different heating temperature ranges are designed according to the different incoming material temperatures, with different voltages applied at different temperatures. This enables electromagnetic heating for direct rolling of 16-meter steel billets, effectively controlling the temperature difference and reducing energy consumption. Attached Figure Description

[0019] Figure 1 This is an interface diagram of the billet heating system.

[0020] Figure 2 This is an interface diagram of the parameter setting section of the production line operation module.

[0021] Figure 3 This is a screenshot of the button control section of the production line operation module.

[0022] Figure 4 This is a screenshot of the overall parameter settings interface for the production line operation module.

[0023] Figure 5 This is a screenshot of the parameter settings interface in the header section of the production line operation module. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] like Figure 1 As shown, a low-energy electromagnetic heating method for direct rolling of 16-meter steel billets includes the following steps:

[0026] 1. The bar mill is equipped with four independently controlled electromagnetic coils, each connected to an inverter. The continuous casting billet upstream of the bar mill is directly and quickly fed to the induction heating device by the roller conveyor. The induction heating device automatically compensates for the temperature of the billet according to the incoming billet temperature. After the temperature is reached, the billet is transported to the downstream rolling mill for rolling. The 16-meter-long hot-delivered billet has a limit of ≥830℃ for the surface temperature of the billet head. When the surface temperature of the billet head is 830℃, the surface temperature of the billet tail is not lower than 890℃.

[0027] The electromagnetic coils have a heating power of 1800KW. The four electromagnetic coils are controlled by two sets of rectifier transformers. The heating power of each electromagnetic coil and the target temperature of the billet are controlled in a closed loop. If one set of electromagnetic coils fails, the remaining three sets can be used. The heating speed of the electromagnetic coils is ≥320t / h, the reheating temperature is 100℃, and the heating time is ≤36s. The running speed of the electromagnetic reheating roller is ≥0.44m / s, and the maximum speed of the induction heating roller is ≥1.5m / s. The power consumption per ton of steel is ≤10kW·h / t. The power factor of the power supply is ≥0.92 across the entire power range (measured at the power input terminal). The diameter of the intermediate roller of the coil is 300mm. The surface temperature difference between the head and tail (length direction) of the heated billet is ≤30℃.

[0028] 2. The billet heating system is designed with both single-branch heating and overall heating modes. Heating is applied separately to the head and tail of the billet based on its incoming temperature; this saves electricity and balances temperature differences and flowability fluctuations between the head and tail. The billet heating system includes a power control module, a frequency converter control module, and a production line operation module. The power control module includes a rectifier cabinet, inverters 1, 2, 3, and 4. The frequency converter control module includes inverters 1, 2, 3, and 4. The production line operation module includes parameter setting and button control sections.

[0029] 2.1 Rectifier Cabinet:

[0030] Internal control mode: Local operation indication for power cabinet;

[0031] External control mode: Remote operation indication of power cabinet;

[0032] Prepare: Power cabinet closing indicator;

[0033] Fault 1: Power cabinet rectifier fault indicator 1;

[0034] Fault 2: Power cabinet rectifier fault 2 indication;

[0035] Flow 1: Status indicator of power cabinet return water flow switch 1, green for normal operation and red for malfunction;

[0036] Flow 2: Status indicator of power cabinet return water flow switch 2, green for normal operation and red for malfunction;

[0037] DC Voltage 1: The displayed value of DC voltage 1 in the power supply cabinet;

[0038] DC Voltage 2: The displayed value of DC voltage 2 in the power supply cabinet;

[0039] Inlet water flow: Water flow rate displayed on the power supply cabinet;

[0040] Inlet water pressure: The displayed value of the inlet water pressure of the power cabinet;

[0041] Inlet water temperature: The displayed value of the inlet water temperature of the power cabinet.

[0042] 2.2 Inverter 1:

[0043] Fault: Power cabinet inverter 1 fault indicator;

[0044] Flow 1: Status indicator of power cabinet return water flow switch 1, green for normal operation and red for malfunction;

[0045] Flow 2: Status indicator of power cabinet return water flow switch 2, green for normal operation and red for malfunction;

[0046] Capacitor pressure: Power cabinet capacitor pressure indicator, red indicates abnormality, gray indicates normal;

[0047] Inlet water flow: Water flow rate displayed on the power supply cabinet;

[0048] Inlet water pressure: The displayed value of the inlet water pressure of the power cabinet;

[0049] Inlet water temperature: The displayed value of the inlet water temperature of the power cabinet.

[0050] 2.3 Inverter 2:

[0051] Fault: Power cabinet inverter 1 fault indicator;

[0052] Flow 1: Status indicator of power cabinet return water flow switch 1, green for normal operation and red for malfunction;

[0053] Flow rate 2: Status indicator of power cabinet return water flow switch 2, green for normal and red for abnormal; Capacitor pressure: Power cabinet capacitor pressure indicator, red for abnormal and gray for normal.

[0054] Inlet water flow: Water flow rate displayed on the power supply cabinet;

[0055] Inlet water pressure: The displayed value of the inlet water pressure of the power cabinet;

[0056] Inlet water temperature: The displayed value of the inlet water temperature of the power cabinet.

[0057] 2.4 Inverter 3:

[0058] Fault: Power cabinet inverter 1 fault indicator;

[0059] Flow rate 1: Status indicator of power cabinet return water flow switch 1, green for normal and red for abnormal; Flow rate 2: Status indicator of power cabinet return water flow switch 2, green for normal and red for abnormal; Capacitor pressure: Power cabinet capacitor pressure indicator, red for abnormal and gray for normal.

[0060] Inlet water flow: Water flow rate displayed on the power supply cabinet;

[0061] Inlet water pressure: The displayed value of the inlet water pressure of the power cabinet;

[0062] Inlet water temperature: The displayed value of the inlet water temperature of the power cabinet.

[0063] 2.5 Inverter 4:

[0064] Fault: Power cabinet inverter 1 fault indicator;

[0065] Flow rate 1: Status indicator of power cabinet return water flow switch 1, green for normal and red for abnormal; Flow rate 2: Status indicator of power cabinet return water flow switch 2, green for normal and red for abnormal; Capacitor pressure: Power cabinet capacitor pressure indicator, red for abnormal and gray for normal.

[0066] Inlet water flow: Water flow rate displayed on the power supply cabinet;

[0067] Inlet water pressure: The displayed value of the inlet water pressure of the power cabinet;

[0068] Inlet water temperature: The displayed value of the inlet water temperature of the power cabinet.

[0069] 2.6 1# Inverter:

[0070] Speed: Real-time speed of motor #1;

[0071] Operation: Operating status of motor #1;

[0072] Fault: Fault status of motor #1;

[0073] Reset: Clicking this button will reset the fault of inverter #1.

[0074] 2.7 #2 Inverter:

[0075] Speed: Real-time speed of motor #2;

[0076] Operation: Operating status of motor #2;

[0077] Fault: Fault status of motor #2;

[0078] Reset: Clicking this button will reset the fault of inverter #2.

[0079] 2.8 3# Inverter:

[0080] Speed: Real-time speed of motor #3 from the frequency converter;

[0081] Operation: Operating status of motor #3;

[0082] Fault: Fault status of motor #3 inverter;

[0083] Reset: Click this button to reset the fault of inverter #3.

[0084] 2.9 4# Inverter:

[0085] Speed: Real-time speed of motor #4 from frequency converter;

[0086] Operation: Operating status of motor #4 of the frequency converter;

[0087] Fault: Fault status of motor #4 of the frequency converter;

[0088] Reset: Clicking this button will reset the fault of inverter #4.

[0089] 2.10 Production line operation module, such as Figure 2 As shown.

[0090] Inverter 1 setpoint: Output voltage setting value of Inverter 1;

[0091] Inverter 2 setpoint: Output voltage setting value of Inverter 2;

[0092] Inverter 3 setpoint: Output voltage setting value of Inverter 3;

[0093] Inverter 4 setpoint: Output voltage setting value of Inverter 4;

[0094] Roller speed: The speed setting of the roller conveyor when the heating furnace is disabled;

[0095] Roller heating speed: The set speed of the roller conveyor during heating.

[0096] The overall heating mode is as follows: when the segmented temperature is not selected before input, the electromagnetic coil will output voltage according to the four set values ​​of inverter 1, inverter 2, inverter 3 and inverter 4 set by the billet heating system. During heating, the roller conveyor will run according to the set value of roller conveyor heating speed.

[0097] When the single-branch heating mode is selected before segmented temperature input and head heating is selected, if the temperature acquisition value does not meet the temperature range set by the head parameters, the electromagnetic coil will output voltage according to the four set values ​​of inverter 1, inverter 2, inverter 3, and inverter 4. During heating, the roller conveyor will run according to the roller conveyor heating speed set value.

[0098] The parameter settings include the head heating time, furnace front deceleration time, furnace rear deceleration time, temperature acquisition time, and speed-up priority shutdown time. The head heating time, when the head heating mode is selected, is the set value for the transmission speed increase after a delay following a signal from the #4 heat detector after the billet exits the furnace, accelerating to the set value for the roller conveyor speed. The furnace front deceleration time is the set value for the transmission speed decrease following a delay following a signal from the #1 heat detector after the billet exits the straightener, decelerating to the set value for the roller conveyor heating speed. The furnace rear deceleration time is the set value for the delay following a signal from the #4 heat detector after the billet exits the furnace. The speed of the roller conveyor after the furnace is reduced to the set value of the roller conveyor heating speed; Temperature acquisition time: the timer starts after the billet exits the straightener No. 1 heat detector receives a signal, and the average value of the maximum values ​​of No. 1 and No. 2 heat meters is taken as the acquisition value within the set time; Speed-up priority shutdown time: when the billet exits the furnace and the No. 4 heat detector receives a signal, and after the head heating time is delayed by the set value, the roller conveyor starts to speed up. After speeding up, the speed-up priority shutdown time is delayed by the set value, and the selected inverter will be shut down first. Other unselected inverters will be shut down after the billet has completely exited the furnace.

[0099] Overall parameter settings are as follows Figure 4 As shown, the header parameter settings are as follows: Figure 5 As shown.

[0100] Production line operation module button control section, such as Figure 3 As shown.

[0101] Selecting temperature segmentation and head heating indicates that the electromagnetic heating will operate in head heating mode. The heating speeds of inverters 1, 2, 3, 4, and the roller conveyor will operate according to the voltage and speed settings in the head parameters corresponding to the temperature acquisition values.

[0102] Electromagnetic heating disabled if not selected: Single-unit start / stop: Inverter 1, Inverter 2, Inverter 3, and Inverter 4 will start / stop according to the signals from heat detector #1 and heat detector #4.

[0103] Start-up: With the rectifier, inverter 1, inverter 2, inverter 3, and inverter 4 all closed, inverter 1 will start automatically when the #1 thermal detector receives a signal. Inverter 2 will start after a 2-second delay, inverter 3 will start after a 4-second delay, and inverter 4 will start after a 6-second delay.

[0104] Stop: 1) If "Speed-up priority shutdown inverter" is not selected, inverters 1, 2, 3, and 4 will be shut down after the #4 thermal detection signal goes from present to absent. 2) If "Speed-up priority shutdown inverter" is selected, the selected inverter cabinet will be shut down first after the roller conveyor speed-up delay setting value, and then the unselected inverter cabinet will be shut down after the #4 thermal detection signal goes from present to absent.

[0105] Continuous operation: After the rectifier and inverter are switched on, the inverter cabinet will start working directly. To stop operation, the inverter must be turned off first, followed by the rectifier.

[0106] Select "Disable Electromagnetic Heating": When selected, the roller conveyor will operate according to the set roller conveyor speed and will not be affected by other factors.

[0107] 3. To further reduce power consumption and solve the problem of large temperature differences between the billets, the billet heating system is designed with 10 heating temperature segments and different heating speeds. After being set, the system automatically selects the given voltage for each of the 10 temperature segments according to the different temperatures of the incoming billets, so that the temperature after passing through the electromagnetic heating furnace is locked within a limited range, reducing the temperature difference between the billets and reducing power consumption.

[0108] Because steelmaking speeds vary, and the time from steelmaking to rolling also differs, the incoming material temperatures inevitably differ. If the same power is used to heat billets at different temperatures, the temperature difference between billets after reheating will be too large. Billets with high incoming material temperatures will reach excessively high temperatures after reheating, while billets with low incoming material temperatures may not even reach the rolling requirements. Furthermore, the large temperature variations between billets make line adjustments impossible. Therefore, the billet reheating system is designed with 10 heating temperature segments and different heating rates. Based on production design, the incoming material temperature will not be lower than 830℃ and will not exceed 970℃. These 10 temperature segments are divided into 14℃ intervals, corresponding to heating rates of 0.41m / s-0.5m / s. Each 0.01m / s change in heating rate corresponds to a temperature segment, and the heating time automatically adjusts according to the incoming material temperature.

[0109] Specifically, when the incoming material temperature is between 820℃ and 834℃, the heating voltage given to each of the four electromagnetic coils is 1300V, and the heating speed is 0.41m / s. When the incoming material temperature is between 956℃ and 970℃, the heating voltage given to the four electromagnetic coils will automatically adjust to 1200V, 1150V, 1100V, and 950V, and the heating speed will automatically become 0.5m / s.

[0110] This invention is not limited to the above-described embodiments. Anyone should know that any structural changes made under the guidance of this invention, and any technical solutions that are the same as or similar to this invention, fall within the protection scope of this invention.

[0111] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. A low-energy electromagnetic heating method for direct rolling of 16-meter steel billets, characterized in that, Includes the following steps: S1. The bar wire is equipped with four independently controlled electromagnetic coils, and each electromagnetic coil is connected to an inverter. S2. The billet heating system is designed with single-branch heating mode and overall heating mode. The billet head and tail are heated separately based on the billet's incoming temperature. In overall heating mode, if the segmented temperature setting is not selected before input, the electromagnetic coil will output voltage according to the four set values ​​of inverter 1, inverter 2, inverter 3, and inverter 4. During heating, the roller conveyor will operate according to the set roller conveyor heating speed. In single-branch heating mode, if the segmented temperature setting is selected before input, head heating is selected. If the temperature collected does not meet the set temperature range of the head parameters, the electromagnetic coil will output voltage according to the four set values ​​of inverter 1, inverter 2, inverter 3, and inverter 4. During heating, the roller conveyor will operate according to the set roller conveyor heating speed. S3. The billet heating system is designed with 10 heating temperature segments and different heating rates. After being set, it automatically selects the given voltage for each of the 10 temperature segments according to the different incoming temperatures of the billet, so that the temperature after passing through the electromagnetic heating furnace is locked within a limited range.

2. The low-energy electromagnetic heating method for direct rolling of 16-meter steel billets according to claim 1, characterized in that, In step S1, the continuously cast billet upstream of the bar production line is directly and quickly fed to the induction heating device by the roller conveyor. The induction heating device automatically compensates the billet temperature according to the incoming billet temperature. After the billet reaches the required temperature, it is transported to the downstream rolling mill for rolling. The 16-meter-long hot-delivered billet has a limit of ≥830°C for the surface temperature of the billet head. When the surface temperature of the billet head is 830°C, the surface temperature of the billet tail is not lower than 890°C.

3. The low-energy electromagnetic heating method for direct rolling of 16-meter steel billets according to claim 1, characterized in that, The heating power of the electromagnetic coil in step S1 is 1800KW. The four electromagnetic coils are controlled by two sets of rectifier transformers. The heating power of each electromagnetic coil and the target temperature of the billet are controlled in a closed loop. If one set of electromagnetic coils fails, it is discarded and the remaining three sets are used. The heating speed of the electromagnetic coils is ≥320 t / h, the reheating temperature is 100℃, and the heating time is ≤36s. The running speed of the electromagnetic reheating roller is ≥0.44 m / s, and the maximum speed of the induction heating roller is ≥1.5m / s.

4. The low-energy electromagnetic heating method for direct rolling of 16-meter steel billets according to claim 1, characterized in that, The billet heating system in step S2 is equipped with a power control module, a frequency converter control module, and a production line operation module. The power control module includes a rectifier cabinet, inverter 1, inverter 2, inverter 3, and inverter 4. The frequency converter control module includes frequency converter 1, frequency converter 2, frequency converter 3, and frequency converter 4. The production line operation module includes a parameter setting section and a button control section.

5. The low-energy electromagnetic heating method for direct rolling of 16-meter steel billets according to claim 4, characterized in that, The parameter settings include head heating time, furnace front deceleration time, furnace rear deceleration time, temperature acquisition time, and speed-up priority shutdown time. The head heating time is set after the #4 heat detector detects a signal after the billet exits the furnace (when head heating mode is selected), with a delay of the set value, and the speed is increased to the set value for the roller conveyor speed. The furnace front deceleration time is set after the #1 heat detector detects a signal after the billet exits the straightener, with a delay of the set value, and the speed is reduced to the set value for the roller conveyor heating speed. The furnace rear deceleration time is set after the #4 heat detector detects a signal after the billet exits the furnace (with a delay of the set value). After the furnace is activated, the roller conveyor speed is reduced to the set value of the roller conveyor heating speed; Temperature acquisition time: the timer starts after the billet exits the straightener #1 heat detector receives a signal, and the average value of the maximum values ​​of the #1 and #2 heat meters is taken as the acquisition value within the set time; Speed-up priority shutdown time: after the billet exits the furnace, when the #4 heat detector receives a signal, and after a delay of the head heating time set value, the roller conveyor starts to speed up. After speeding up, a delay of the speed-up priority shutdown time set value is applied, and the selected inverter will be shut down first. Other unselected inverters will be shut down after the billet has completely exited the furnace.

6. The low-energy electromagnetic heating method for direct rolling of 16-meter steel billets according to claim 1, characterized in that, The billet heating system in step S3 is designed with 10 heating temperature segments and different heating rates. According to the production design, the incoming material temperature will not be lower than 830℃ and will not be higher than 970℃. The temperature range of 830℃ to 970℃ is divided into 10 temperature segments, with each segment lasting 14℃. The corresponding heating rate is 0.41m / s-0.5m / s. The heating rate changes every 0.01m / s, which corresponds to a temperature segment. The heating time is automatically adjusted according to the incoming material temperature.

7. The low-energy electromagnetic heating method for direct rolling of 16-meter steel billets according to claim 6, characterized in that, When the incoming material temperature is between 820℃ and 834℃, the heating voltage given to each of the four electromagnetic coils is 1300V, and the heating rate is 0.41m / s. When the incoming material temperature is between 956℃ and 970℃, the heating voltage given to the four electromagnetic coils will automatically adjust to 1200V, 1150V, 1100V, and 950V, and the heating rate will automatically become 0.5m / s.

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