Billet electromagnetic induction heating system and control method, billet production line

Abstract

The application discloses a billet electromagnetic induction heating system and a control method and a billet production line. The system comprises n regional heating units, each of which comprises a power module, a control module, a temperature measuring module, a conveying mechanism for conveying billets, and a plurality of induction heaters. The plurality of induction heaters are arranged at equal intervals on the conveying mechanism, and each induction heater is provided with a through hole for the heated billet to pass through. The control module is used to control the operating power of the induction heater according to the surface temperature of the heated billet and the corresponding surface target temperature, the end face center temperature and the corresponding end face center target temperature, so as to realize the heating of the billet, and to control the corresponding conveying mechanism to move during the heating process, so as to realize the reciprocating motion of the billet and the conveying of the billet to the next process link. The application can realize the heating of the cold billet and meet the continuous production rhythm, and ensure the uniformity of the cross section and the axial temperature of the billet.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic induction heating rolling technology, and particularly relates to an electromagnetic induction heating system and control method for high-end alloy steel billets, and a steel billet production line. Background Technology

[0002] The principle of electromagnetic induction heating of steel billets is as follows: when an alternating current of a certain frequency is passed through an induction coil, an alternating magnetic field is generated around the coil. The steel billet, situated within this magnetic field, generates an induced current. This induced current flows through the billet, forming a circuit and simultaneously producing heat—Joule heating—thus raising the billet's temperature. As can be seen from the principle of electromagnetic induction heating, this technology has the advantages of being green, environmentally friendly, and having zero carbon emissions. In addition, compared with traditional heating methods, electromagnetic induction heating technology also offers a series of advantages such as high heating efficiency, rapid heating rate, good heating quality, high temperature control accuracy, good heating temperature uniformity, small equipment footprint, and high degree of system automation. Based on these advantages, electromagnetic induction heating technology has been widely applied in many industries, including steel rolling, heat treatment, and heat processing.

[0003] Electromagnetic induction heating is generally classified into two types based on the magnetic field form: longitudinal magnetic field heating (longitudinal magnetic heating) and transverse magnetic field heating (transverse magnetic heating). In longitudinal magnetic heating, the inductor coil is typically helical, with its cross-sectional shape matching the cross-section of the steel billet being heated. The billet is located inside the coil channel. Longitudinal magnetic heating is mainly used for heating square and round billets, rails, and structural steel. During heating, the induced current within the steel itself is concentrated on the surface due to the skin effect, thus it is considered surface heating. In transverse magnetic heating, the inductor coil is generally distributed across the upper and lower surfaces of the billet being heated. During heating, the induced current circulates throughout the entire thickness of the billet. It is mainly used for heating steel plates of different thicknesses. During heating, the overall temperature of the steel plate's thickness section rises, thus it is considered overall heating.

[0004] High-end alloy steel billets, such as titanium alloy billets, are generally produced as circular billets, which are then heated and rolled or hot-worked. Titanium, as a rare metal with unique physicochemical properties, is widely used in cutting-edge technological fields such as aerospace, biomedicine, military, and automobiles. It is commonly used to produce high-quality, corrosion-resistant, lightweight structural materials, novel functional materials, and important bioengineering materials. The initial material cost of titanium alloy billets is relatively high, and its production capacity differs from that of continuously cast steel billets, which can reach one or two hundred tons per hour. The production capacity of titanium alloy billets is generally around ten tons per hour, primarily to ensure the quality of the billets.

[0005] In the processing of titanium alloy steel billets, high precision in temperature control is required. To ensure processing quality and reduce waste of high-cost raw materials, electromagnetic induction heating is indispensable for pre-processing titanium alloy steel billets. Based on the circular cross-sectional shape of the titanium alloy steel billet, longitudinal magnetic fields can be used for heating. However, since longitudinal magnetic heating is surface heating, ensuring uniform temperature across the entire cross-section and along the length of the billet during heating is difficult, especially when heating cold billets. The temperature at the center of the billet needs to rise through heat conduction after the surface temperature has increased, and the heating process through heat conduction at the center is relatively slow compared to direct surface heating. Furthermore, especially in situations requiring continuous production and maintaining a consistent processing pace, a single heating system is insufficient.

[0006] Currently, a combination of gas-fired furnaces and induction heating is used to ensure continuous production. The steel billet is heated to a certain temperature in the gas-fired furnace and then transferred to the induction heating furnace. The induction heating furnace provides supplemental heating to bring the steel billet to the temperature required for rolling. However, this method still requires a large gas-fired furnace, which faces the pressure of carbon emissions and remains unsustainable in the long run. Summary of the Invention

[0007] The purpose of this invention is to provide a billet electromagnetic induction heating system and control method, and a billet production line, to solve the problem that longitudinal magnetic heating is difficult to guarantee the uniformity of the billet cross-sectional temperature and axial temperature, as well as the problem that traditional heating methods require gas furnaces, resulting in high cost, large size and carbon emission pressure.

[0008] The present invention solves the above-mentioned technical problems through the following technical solution: a steel billet electromagnetic induction heating system, comprising n regional heating units arranged sequentially along the steel billet conveying direction, wherein n≥1;

[0009] Each of the aforementioned heating units includes a power module, a control module, a temperature measurement module, a conveying mechanism for conveying steel billets, and m induction heaters arranged sequentially along the steel billet conveying direction; the m induction heaters are equally spaced on the conveying mechanism, and each induction heater is provided with a through hole for the steel billet to be heated to pass through.

[0010] The temperature measuring module, power supply module, and conveying mechanism are electrically connected to the control module, and the power supply module is electrically connected to each of the induction heaters. The temperature measuring module is used to measure the surface temperature and end-face center temperature of the heated steel billet. The control module is used to control the electrical parameters output by the power supply module based on the surface temperature and corresponding target surface temperature, end-face center temperature and corresponding target end-face center temperature of the heated steel billet, thereby controlling the operating power of the induction heater to heat the steel billet. It is also used to control the corresponding conveying mechanism during the heating process to achieve the reciprocating motion of the steel billet. When the steel billet reaches the corresponding target surface temperature and end-face center temperature, the control module controls the corresponding conveying mechanism to move the steel billet to the next heating unit or the next production process.

[0011] Furthermore, the overall arrangement length L1 of a single regional heating unit is greater than the length L2 of a single heated steel billet, wherein the overall arrangement length L1 refers to the distance between the first end of the first induction heater and the second end of the last induction heater, the first and the first ends both correspond to the material receiving end, and the last and the second ends both correspond to the material discharging end.

[0012] Preferably, the overall arrangement length L1 of a single heating unit is equal to the sum of the length L2 of a single heated steel billet and the heating area length B2 of a single induction heater;

[0013] The length B2 of the heating area of ​​a single induction heater is equal to the gap S between the heating areas of two adjacent induction heaters;

[0014] In the reciprocating motion, the unidirectional stroke of the billet is equal to twice the length B2 of the heating zone of a single induction heater.

[0015] Furthermore, the number n of the regional heating units is equal to the total heating time t. f With the rhythm duration t of continuous production s The ratio, where the total heating time t f This refers to the time required to heat a steel billet from room temperature to the final target temperature.

[0016] Furthermore, the conveying mechanism includes m+1 conveying units, each of which includes a conveyor roller and a variable frequency motor. The input end of the variable frequency motor is electrically connected to the control module, and its output end is connected to the conveyor roller. Each induction heater is located between two adjacent conveyor rollers.

[0017] Preferably, the conveying section of each of the conveying rollers is V-shaped, and the conveying section refers to the part that contacts the steel billet.

[0018] Furthermore, the temperature measuring module includes a first temperature measuring module and a second temperature measuring module. The first temperature measuring module is located on the heating center line and is used to measure the center temperature of the end face of the steel billet. The second temperature measuring module is located on one side of the heating center line and there are m+1 of them. Among them, m-1 second temperature measuring modules are used to measure the surface temperature of the steel billet between two adjacent induction heaters, and the remaining two second temperature measuring modules are used to measure the surface temperature of the steel billet at the first end of the first induction heater and the surface temperature of the steel billet at the second end of the last induction heater, respectively.

[0019] Based on the same inventive concept, the present invention also provides a control method for the above-described electromagnetic induction heating system for steel billets, comprising the following steps:

[0020] Step S101: Control the first zone heating unit to heat the steel billet. When the steel billet reaches the first surface target temperature and the first end face center target temperature, transfer the steel billet to the next zone heating unit.

[0021] Step S102: Repeat step S101. When the steel billet is heated to the target temperature of the nth surface and the target temperature of the center of the nth end face by the nth region heating unit, the steel billet is transferred to the next production process.

[0022] The specific control process for heating the steel billet by each of the aforementioned regional heating units includes:

[0023] Obtain the surface temperature and end-face center temperature of the steel billet;

[0024] The electrical parameters output by the power supply module are controlled based on the surface temperature and the corresponding target surface temperature, the end face center temperature and the corresponding target end face center temperature, thereby controlling the operating power of m induction heaters to heat the steel billet; during the heating process, the corresponding conveying mechanism is controlled to achieve the reciprocating motion of the steel billet.

[0025] Furthermore, based on the surface temperature and the corresponding target surface temperature, the end face center temperature and the corresponding target end face center temperature, the electrical parameters output by the power supply module are controlled, thereby controlling the operating power of the m induction heaters, specifically including:

[0026] Control the m induction heaters to operate at rated power;

[0027] When the surface temperature of the steel billet reaches the corresponding target surface temperature, the operating power of the induction heater is controlled according to the surface temperature and the corresponding target surface temperature to maintain the surface temperature of the steel billet at the corresponding target surface temperature.

[0028] When the center temperature of the end face of the billet reaches the corresponding target temperature, the billet is transferred to the next heating unit or the next production process.

[0029] Furthermore, the statement that the surface temperature of the steel billet reaches or is maintained at the corresponding target surface temperature means that it is higher than the corresponding target surface temperature, and the excess is 0 to 20°C.

[0030] The term "the end face center temperature of the billet reaches the corresponding end face center target temperature" means that it is higher than the corresponding end face center target temperature, and the excess margin is 0 to 20°C.

[0031] The target temperature of the nth surface is higher than the final target temperature of the billet, and the target temperature of the center of the nth end face is equal to or higher than the final target temperature of the billet.

[0032] Furthermore, the control method also includes: during continuous production, when the steel billets in each heating unit are simultaneously heated to the corresponding target surface temperature and target end face center temperature, while sending the material receiving instruction through the control module of the first heating unit, controlling the steel billet of the nth heating unit to enter the next production process, the steel billet of the (n-1)th heating unit to enter the nth heating unit, the steel billet of the (n-2)th heating unit to enter the (n-1)th heating unit, and so on, the steel billet of the first heating unit to enter the second heating unit, and the incoming cold steel billet to enter the first heating unit.

[0033] Based on the same inventive concept, the present invention also provides a billet production line, including the billet electromagnetic induction heating system as described above.

[0034] Beneficial effects

[0035] Compared with the prior art, the advantages of the present invention are as follows:

[0036] 1. This invention ensures the uniformity of the cross-sectional and axial temperature of the billet by real-time monitoring and control of the center temperature of the billet end face and the surface temperature of the billet, thus effectively guaranteeing the processing quality of the billet in subsequent processes.

[0037] 2. By matching the heating zone with the actual working conditions of the production site, this invention enables continuous production and processing of cold steel billets without the need for traditional gas furnaces, truly achieving green, environmentally friendly, and zero-carbon emission induction heat processing production.

[0038] 3. This invention has a high degree of automation. Attached Figure Description

[0039] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a diagram showing the arrangement of heating units in each region of the electromagnetic induction heating system for steel billets in this embodiment of the invention.

[0041] Figure 2 This is a schematic diagram of the structure of a single-area heating unit in an embodiment of the present invention;

[0042] Figure 3 This is a control circuit diagram of a single-area heating unit in an embodiment of the present invention;

[0043] Figure 4 This is a diagram showing the dimensional relationships of various parts in a single-area heating unit in an embodiment of the present invention;

[0044] Figure 5 This is a control principle diagram of the electromagnetic induction heating system for steel billets in an embodiment of the present invention;

[0045] Figure 6 This is a control circuit diagram of the conveyor roller of a single-area heating unit in an embodiment of the present invention;

[0046] Figure 7 This is a temperature acquisition circuit diagram of the temperature measurement module of a single area heating unit in an embodiment of the present invention.

[0047] Among them, 1-control module, 2-power supply module, 3-second temperature measuring module, 4-induction heater, 5-conveyor roller, 6-frequency conversion motor, 7-first temperature measuring module, and 8-heated steel billet. Detailed Implementation

[0048] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] The technical solutions of this application will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0050] The present invention provides an electromagnetic induction heating system for steel billets, comprising n regional heating units arranged sequentially along the billet conveying direction, wherein n ≥ 1, as shown in the example. Figure 1 As shown; each of the aforementioned heating units includes a power module 2, a control module 1, a temperature measuring module, a conveying mechanism for conveying steel billets, and m induction heaters 4 arranged sequentially along the steel billet conveying direction; the m induction heaters 4 are equally spaced on the conveying mechanism, and each induction heater 4 has a through hole for the heated steel billet 8 to pass through, such as Figure 2 As shown.

[0051] like Figure 1 As shown, the billet is conveyed from right to left. The rightmost heating unit is the first heating unit, and so on, with the leftmost heating unit being the nth heating unit. These n heating units heat the billet from room temperature to the required temperature before rolling (i.e., the final target temperature). Figure 2 As shown, in a single zone heating unit, the rightmost induction heater 4 is the first induction heater 4, and the leftmost induction heater 4 is the last induction heater 4. The steel billet is fed from the right end to the zone heating unit for heating. After heating is completed, it is discharged from the left end and enters the next zone heating unit. The first end of each induction heater 4 is defined as the feeding end, and its second end is the discharging end.

[0052] like Figure 3 As shown, the temperature measuring module, power supply module 2, and conveying mechanism are electrically connected to the control module 1, and the power supply module 2 is electrically connected to each induction heater 4.

[0053] The temperature measuring module is used to measure the surface temperature and end-face center temperature of the heated steel billet 8. In one specific embodiment of the invention, the temperature measuring module includes a first temperature measuring module 7 and a second temperature measuring module 3. The first temperature measuring module 7 is located on the heating center line and is used to measure the end-face center temperature of the steel billet. There are m+1 second temperature measuring modules 3, which are arranged sequentially along the conveying direction of the steel billet and on one side of the heating center line. The middle m-1 second temperature measuring modules 3 are used to measure the surface temperature of the steel billet between two adjacent induction heaters 4, and the first and last two second temperature measuring modules 3 are used to measure the surface temperature of the steel billet at the first end of the first induction heater 4 and the surface temperature of the steel billet at the second end of the last induction heater 4, respectively. That is, the m+1 second temperature measuring modules 3 are used to measure the surface temperature of the heated steel billet 8 along its length. Using m+1 second temperature measuring modules 3 to monitor the surface temperature of the steel billet is beneficial to the uniformity of the overall temperature during the heating of the steel billet. The heating center line is the center line or axis of the heated steel billet 8.

[0054] like Figure 2As shown, the first temperature measuring module 7 is located on the side of the second end of the last induction heater 4 via an electric telescopic rod and is situated at the heating centerline. To ensure smooth billet transfer after induction heating, the control module 1 controls the electric telescopic rod to shorten, thereby lowering the first temperature measuring module 7 and allowing the billet to be smoothly transferred to the next heating unit or the next production process. During heating, the electric telescopic rod is then extended to measure the center temperature of the billet's end face. The extension amount of the electric telescopic rod can be determined through on-site debugging. Each time, the extension and retraction of the electric telescopic rod is controlled according to the determined extension amount, ensuring both accurate measurement of the center temperature of the end face and smooth billet transfer.

[0055] Power module 2 is used to output corresponding electrical parameters according to the instructions of control module 1, so as to control the operating power of induction heater 4, so that induction heater 4 generates an alternating magnetic field under alternating excitation at a specified frequency, thereby heating the steel billet. Multiple power modules 2 can be set according to the number of induction heaters 4 in each zone heating unit. For example, when the number of induction heaters 4 in a zone heating unit is 6, two power modules 2 are set, with each power module 2 corresponding to 3 induction heaters 4.

[0056] like Figure 2 and 3 As shown, the conveying mechanism includes m+1 conveying units. Each conveying unit includes a conveyor roller 5 and a variable frequency motor 6. The input end of the variable frequency motor 6 is electrically connected to the control module 1, and its output end is connected to the conveyor roller 5. Each induction heater 4 is located between two adjacent conveyor rollers 5. The control module 1 controls the speed and forward / reverse rotation of the variable frequency motor 6. That is, the speed control of the variable frequency motor 6 realizes the different speeds required during the billet conveying or reciprocating motion. The forward (or reverse) rotation control of the variable frequency motor 6 realizes the conveying of the billet to the next heating unit or the next process (the conveying motion of the billet). The forward / reverse rotation control of the variable frequency motor 6 realizes the reciprocating motion of the billet during the heating process.

[0057] In one specific embodiment of the present invention, the conveying section of each conveying roller 5 is V-shaped, and the conveying section refers to the part that contacts the steel billet. The V-shaped conveying section ensures that the steel billet does not have any displacement in the direction perpendicular to the heating center line during the conveying and reciprocating motion, so that the first temperature measuring module 7 can stably monitor the end face center temperature of the steel billet during the reciprocating motion.

[0058] The control module 1 is used to control the electrical parameters output by the power module 2 based on the surface temperature and corresponding target surface temperature, end face center temperature and corresponding target end face center temperature of the heated steel billet 8, thereby controlling the operating power of each induction heater 4 to achieve heating of the steel billet; and to control the forward and reverse rotation of the variable frequency motor 6 of the conveying mechanism during the heating process to achieve reciprocating motion control of the steel billet. When the steel billet reaches the target surface temperature and the target end face center temperature (i.e., the heating of the heating unit in this area is completed), the variable frequency motor 6 of the conveying mechanism is controlled to rotate forward (or reverse) to convey the steel billet to the next heating unit or the next production process.

[0059] The control modules 1 of each heating unit communicate with each other. The control module 1 of the first heating unit also communicates with the billet production line so that the billet production line can provide cold billets to the first heating unit for heating in a timely manner.

[0060] To ensure that the total heating time and number of heating cycles are consistent for all parts of the billet along its length in the induction heater 4 when the billet is heated in a single heating unit, the overall length of the single heating unit needs to be matched with the length of a single heated billet 8. The specific matching method is as follows:

[0061] like Figure 4 As shown, the overall arrangement length L1 of a single area heating unit refers to the distance between the first end of the first induction heater 4 and the second end of the last induction heater 4. Let the length of a single heated steel billet 8 be L2, the length of a single induction heater 4 be B1, the length of the induction coil in a single induction heater 4 be B2, and the length of the induction coil in a single induction heater 4 be the length of the heating area of ​​a single induction heater 4. The gap between two adjacent heating areas is S.

[0062] The length of a single induction heater 4 is greater than the length of the induction coil within the single induction heater 4, that is:

[0063] B1>B2 (1)

[0064] The overall length of a single heating unit is greater than the length of a single heated steel billet 8, that is:

[0065] L1>L2 (2)

[0066] The overall length of a single heating unit is equal to the sum of the length of a single heated steel billet 8 and the length of the heating area of ​​a single induction heater 4, that is:

[0067] L1 = L2 + B2 (3)

[0068] The length of the heating area of ​​a single induction heater 4 is equal to the gap between the heating areas of two adjacent induction heaters, that is:

[0069] B2 = S (4)

[0070] When the steel billet is heated in a single-area heating unit, it reciprocates on the conveyor roller 5. During this reciprocating motion, the unidirectional stroke H of the steel billet is equal to twice the length of the heating area of ​​a single induction heater 4, that is:

[0071] H = 2 * B² (5)

[0072] Equation (1) ensures a safe electrical clearance between the induction coil and the outer shell of the induction heater 4, and ensures insulation between the coil and the outer shell; Equation (2) is to ensure that as many areas as possible are inside the induction heater 4 during the heating process of the billet. The through hole of the induction heater 4 is both a heating channel and a heat preservation function - reducing the heat exchange between the heated billet 8 and the air, thereby shortening the heating time, improving the heating speed and heating efficiency, and thus reducing the heating energy consumption; Equations (3) to (5) mainly function to ensure that the heating time of each part of the billet in the length direction is the same when the heated billet 8 is heated in a single area heating unit - since the reciprocating unidirectional stroke of the heated billet 8 in a single area heating unit is twice the length of the heating area of ​​a single induction heater 4, and the length of the heating area of ​​a single induction heater 4 is equal to the gap between two adjacent heating areas, so that the section of the billet in the heating area of ​​the induction heater 4 has the same number of heating times as the billet between two adjacent heating areas, that is, the same heating time, thereby ensuring the uniformity of the overall temperature of the billet in the length direction after heating.

[0073] To achieve continuous production after heating cold steel billets, the number of zone heating units, n, is determined based on the production rhythm of a single steel billet (i.e., the duration of continuous production). s , t s This equals the heating time of the billet in each heating unit (the heating time in each heating unit is equal), the billet specifications, and the final target temperature T required for heating the billet. f The total power capacity of the production line is used to determine this, specifically:

[0074] Through finite element analysis and calculation, combined with the total power capacity of the production line, the method for heating steel billets of the corresponding specifications from room temperature to the final target temperature T is calculated. f The required time, i.e., the total heating time t f , t f This is also equal to the sum of the time required for each heating unit to heat the billet to the corresponding surface target temperature and end face center target temperature (i.e., the heating time of each heating unit).

[0075]

[0076] After determining the number of regional heating units, based on the actual heating situation of the billet during on-site system debugging, the target surface temperature and target end-face center temperature of the billet after a heating time ts in each regional heating unit are determined and stored in the corresponding control module 1 in a database. Dividing the billet electromagnetic induction heating system into n regional heating units is beneficial to improving billet production capacity and ensuring heating uniformity and heating effect while meeting capacity requirements.

[0077] Table 1 shows the target surface temperature and target end-face center temperature of the billet to be achieved within the heating time ts of each heating unit.

[0078]

[0079] Based on the same inventive concept, embodiments of the present invention also provide a control method for the electromagnetic induction heating system for steel billets as described above, such as... Figure 5 As shown, the control method includes the following steps:

[0080] Step S101: Control the first zone heating unit to heat the steel billet. When the steel billet reaches the first surface target temperature T... S1 and the target temperature T at the center of the first end face C1 At that time, the steel billet is transferred to the next heating unit.

[0081] Step S102: Repeat step S101, when the billet is heated to the target surface temperature T of the nth surface through the nth region heating unit. Sn and the target temperature T at the center of the nth end face Cn At that time, the steel billet is transferred to the next production process.

[0082] The specific control process for heating the steel billet in each heating unit includes:

[0083] Step S201: Obtain the surface temperature and end face center temperature of the steel billet;

[0084] Step S202: Based on the surface temperature and the corresponding target surface temperature, the end face center temperature and the corresponding target end face center temperature, control the electrical parameters output by the power supply module, and then control the operating power of m induction heaters to heat the steel billet; during the heating process, control the corresponding conveying mechanism to achieve the reciprocating motion of the steel billet.

[0085] To ensure continuous production, the heating time for the steel billet is equal in each heating unit. When the nth heating unit heats the steel billet to the target surface temperature T of the nth surface, Sn and the target temperature T at the center of the nth end face CnThen, the conveyor rollers of the n heating zones simultaneously drive their respective heated steel billets in one direction—the heated steel billet in the nth heating zone is conveyed out and enters the next production process of the production line, the heated steel billet in the (n-1)th heating zone is conveyed to the nth heating zone, the heated steel billet in the (n-2)th heating zone is conveyed to the (n-1)th heating zone, and so on, the heated steel billet in the 1st heating zone is conveyed to the 2nd heating zone, and the room temperature cold steel billet enters the 1st heating zone, realizing continuous production.

[0086] Step S202 specifically includes:

[0087] Control m induction heaters to operate at full power or rated power so that the surface temperature of the steel billet can quickly reach the corresponding target surface temperature;

[0088] When the surface temperature of the billet reaches the corresponding target surface temperature, the operating power of the induction heater is controlled according to the surface temperature and the corresponding target surface temperature to maintain the surface temperature of the billet at the corresponding target surface temperature.

[0089] During the process of maintaining the surface temperature at the corresponding target surface temperature, the surface temperature is conducted to the center of the billet, and the center temperature rises. When the center temperature of the end face of the billet reaches the corresponding target temperature of the end face, it indicates that the heating in the heating unit of that area has been completed, and the billet is transferred to the next heating unit or the next production process.

[0090] When the steel billet is transferred between heating units, its surface and end-face center temperatures decrease due to heat exchange with the air. To prevent this decrease from causing the billet to fail to meet target temperature requirements, the surface temperature of the billet should be 0–20°C higher than the corresponding target surface temperature, and the excess temperature should be maintained at or above the target surface temperature. Similarly, the end-face center temperature of the billet should be 0–20°C higher than the corresponding target end-face center temperature. For example, after the first heating unit completes heating the billet, its surface temperature should be higher than the first target surface temperature T. S1 The center temperature of the end face of the steel billet should be higher than the target temperature T of the center of the first end face. C1 And the excess is 20℃.

[0091] In each heating zone, when the billet enters, the control module controls the power supply module to energize each induction heater in that heating zone and output rated power or full power. At the same time, it controls the forward and reverse rotation of the conveyor rollers in that heating zone, causing the billet to reciprocate and thus reciprocate for heating. During the heating process, the first and second temperature measuring modules continuously measure the temperature of the heated billet. The measured surface temperature and end-face center temperature are fed back to the control module. The control module compares the fed-back temperature data with the corresponding target surface temperature and end-face center temperature in the database (as shown in Table 1). When both reach the corresponding target surface temperature and end-face center temperature, the power supply module cuts off the power. Meanwhile, to ensure smooth forward conveying of the billet, the first temperature measuring module of that heating zone shortens downward, and the billet is conveyed forward to the next heating zone.

[0092] During continuous heating, the induction heaters operate at rated power until the billet reaches the target surface temperature corresponding to the heating unit in that area, enabling the billet to reach the target surface temperature in the shortest possible time. While maintaining the target surface temperature, heat conduction raises the temperature at the center of the billet's end face, eventually reaching the target temperature at the center of the end face. This effectively reduces the temperature gradient in the radial direction of the billet's cross-section, ensuring the uniformity of the billet's cross-sectional temperature.

[0093] The power margin of the induction heater in the nth heating zone is larger than that in the previous n-1 heating zones (typically 5-10%). When the billet enters the nth heating zone (i.e., the last heating zone), due to the higher power margin of the induction heater, the surface temperature and end-face center temperature of the billet will reach the corresponding target temperature T in a shorter time, even at the rated power output of the induction heater. Sn and T Cn In order to avoid T Sn and T Cn The deviation from the final target temperature Tf of the billet allows more time for heat transfer from the surface to the center, ensuring uniform cross-sectional temperature. Before the billet leaves the nth heating unit, based on production experience data (reaching the temperature requirements for the next processing step, such as rolling), the target surface temperature T of the billet is... Sn The target temperature T at the center of the billet end face should be within 20°C higher than the final target temperature Tf. Cn The cross-sectional temperature of the billet is determined to be equal to or within 20°C above the final target temperature Tf, based on this empirical target temperature difference value, so as to achieve uniformity.

[0094] like Figure 6The diagram shows the control circuit for the conveyor rollers of a single heating zone unit. The LSB1 knob selects the roller for the first heating zone unit. Pressing the SB1 button advances the roller, the SB2 button quickly reverses the roller, the SB3 button slowly advances the roller, the SB4 button slowly reverses the roller, the KSB5 button resets the roller, the SA1 knob controls the roller's emergency stop, and the SA2 knob switches between remote control via a host computer and a local operator console. The PLC digital input module is model 6ES7.

[0095] 323-1BL00-0AA0.

[0096] The control module of the first heating unit communicates with the production line, and the control modules of each heating unit communicate with each other. When the temperature of the heated billet reaches the corresponding target surface temperature and the target end-face center temperature (since the heating time of each heating unit is equal, when each heating unit heats simultaneously, the temperature of the heated billet in each heating unit can simultaneously reach the corresponding target surface temperature and the target end-face center temperature), the control module of the first heating unit notifies the production line to receive the material. At the same time, the billets in each heating unit and the heating units waiting behind the first heating unit are simultaneously conveyed forward. That is, the billet of the nth heating unit enters the next processing step, the billet of the (n-1)th heating unit enters the nth heating unit, the billet of the (n-2)th heating unit enters the (n-1)th heating unit, ... the billet of the 1st heating unit enters the 2nd heating unit, and the cold billet from the production line enters the 1st heating unit, realizing continuous production.

[0097] like Figure 7 The temperature acquisition circuit of the first and second temperature measuring modules of the single-area heating unit shown is provided. The signals from the two temperature measuring instruments are respectively sent to the PLC analog input module, and the PLC analog input module model is 6ES7 331-1KF02-0AB0.

[0098] The above description only discloses specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or modifications that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A billet electromagnetic induction heating system, comprising n regional heating units arranged sequentially along the billet conveying direction, wherein n≥1; characterized in that: Each of the aforementioned heating units includes a power module, a control module, a temperature measuring module, a conveying mechanism for conveying steel billets, and m induction heaters arranged sequentially along the steel billet conveying direction; the m induction heaters are equally spaced on the conveying mechanism, and each induction heater has a through hole for the steel billet to be heated to pass through; the temperature measuring module, the power module, and the conveying mechanism are electrically connected to the control module, and the power module is electrically connected to each of the induction heaters; The temperature measuring module includes a first temperature measuring module and a second temperature measuring module. The first temperature measuring module is located on the heating center line and is used to measure the center temperature of the end face of the steel billet. The second temperature measuring module is located on one side of the heating center line and there are m+1 of them. Among them, m-1 second temperature measuring modules are used to measure the surface temperature of the steel billet between two adjacent induction heaters, and the remaining two second temperature measuring modules are used to measure the surface temperature of the steel billet at the first end of the first induction heater and the surface temperature of the steel billet at the second end of the last induction heater, respectively. The control module is used to control the electrical parameters output by the power module according to the surface temperature and corresponding target surface temperature, end face center temperature and corresponding target end face center temperature of the heated steel billet, thereby controlling the operating power of the induction heater to heat the steel billet, and to control the operation of the corresponding conveying mechanism during the heating process to realize the reciprocating motion of the steel billet. When the steel billet reaches the corresponding target surface temperature and end face center temperature, the control module controls the operation of the corresponding conveying mechanism to transfer the steel billet to the next heating unit or the next production process. Wherein, the overall arrangement length L1 of a single heating unit is greater than the length L2 of a single heated steel billet, and L1 = L2 + B2, where B2 represents the length of the heating area of ​​a single induction heater, and B2 is equal to the gap S between the heating areas of two adjacent induction heaters; the unidirectional stroke of the steel billet in the reciprocating motion is equal to 2 × B2, and the overall arrangement length L1 refers to the distance between the first end of the first induction heater and the second end of the last induction heater, the first and the first ends both correspond to the material receiving end, and the last and the second ends both correspond to the material discharging end.

2. The billet electromagnetic induction heating system according to claim 1, characterized in that: The number n of the regional heating units is equal to the total heating time. t f With the rhythm and duration of continuous production t s The ratio, of which, total heating time t f This refers to the time required to heat a steel billet from room temperature to the final target temperature.

3. The billet electromagnetic induction heating system according to claim 1, characterized in that: The conveying mechanism includes m+1 conveying units, each of which includes a conveyor roller and a variable frequency motor. The input end of the variable frequency motor is electrically connected to the control module, and its output end is connected to the conveyor roller. Each induction heater is located between two adjacent conveyor rollers.

4. The billet electromagnetic induction heating system according to claim 3, characterized in that: Each of the conveying rollers has a V-shaped conveying section, which refers to the part that contacts the steel billet.

5. A control method for a steel billet electromagnetic induction heating system as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Step S101: Control the first zone heating unit to heat the steel billet. When the steel billet reaches the first surface target temperature and the first end face center target temperature, transfer the steel billet to the next zone heating unit. Step S102: Repeat step S101. When the steel billet is heated to the target temperature of the nth surface and the target temperature of the center of the nth end face by the nth region heating unit, the steel billet is transferred to the next production process. The specific control process for heating the steel billet by each of the aforementioned regional heating units includes: Obtain the surface temperature and end-face center temperature of the steel billet; The electrical parameters output by the power supply module are controlled based on the surface temperature and the corresponding target surface temperature, the end face center temperature and the corresponding target end face center temperature, thereby controlling the operating power of m induction heaters to heat the steel billet; during the heating process, the corresponding conveying mechanism is controlled to achieve the reciprocating motion of the steel billet.

6. The control method according to claim 5, characterized in that, Based on the surface temperature and its corresponding target surface temperature, end face center temperature and its corresponding target end face center temperature, the electrical parameters output by the power supply module are controlled, thereby controlling the operating power of the m induction heaters, specifically including: Control the m induction heaters to operate at rated power; When the surface temperature of the steel billet reaches the corresponding target surface temperature, the operating power of the induction heater is controlled according to the surface temperature and the corresponding target surface temperature to maintain the surface temperature of the steel billet at the corresponding target surface temperature. When the center temperature of the end face of the billet reaches the corresponding target temperature, the billet is transferred to the next heating unit or the next production process.

7. The control method according to claim 6, characterized in that, The surface temperature of the steel billet reaching or maintaining the corresponding target surface temperature means being higher than the corresponding target surface temperature, with an excess margin of 0 to 20°C. The term "the end face center temperature of the billet reaches the corresponding end face center target temperature" means that it is higher than the corresponding end face center target temperature, and the excess margin is 0 to 20°C. The target temperature of the nth surface is higher than the final target temperature of the billet, and the target temperature of the center of the nth end face is equal to or higher than the final target temperature of the billet.

8. The control method according to any one of claims 5 to 7, characterized in that, include: During continuous production, when the steel billets in each heating unit are simultaneously heated to the corresponding target surface temperature and target end-face center temperature, while sending the material receiving instruction through the control module of the first heating unit, the steel billet of the nth heating unit is controlled to enter the next production process, the steel billet of the (n-1)th heating unit enters the nth heating unit, the steel billet of the (n-2)th heating unit enters the (n-1)th heating unit, and so on, the steel billet of the first heating unit enters the second heating unit, and the incoming cold steel billet enters the first heating unit.

9. A billet production line, characterized in that, The production line includes a billet electromagnetic induction heating system as described in any one of claims 1 to 4.

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