A heating system for continuous casting billet deformation and a control method thereof, and a continuous casting machine

Abstract

The application discloses a heating system for continuous casting billet deformation and a control method and a continuous casting machine thereof. The heating system comprises a first induction heating unit, a second induction heating unit, a first power supply device, a second power supply device, a first temperature detection unit, a second temperature detection unit and a control device. The first power supply device is connected with the first induction heating unit, the second power supply device is connected with the second induction heating unit, and the control device is connected with the first power supply device, the second power supply device, the first temperature detection unit and the second temperature detection unit. The control device controls the first induction heating unit to be turned on according to the steel grade information of the continuous casting billet, controls the operation power of the first induction heating unit according to the temperature detected by the first temperature detection unit and a first target temperature, and controls the operation power of the second induction heating unit according to the temperature detected by the second temperature detection unit and a second target temperature. The application solves the cracking problem in the deformation process of the continuous casting billet.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of continuous casting billet heating, and particularly relates to a heating system for continuous casting billet deformation and a control method thereof, and a continuous casting machine. BACKGROUND

[0002] There are several ways for steel production, such as traditional mold casting, semi-continuous casting and continuous casting. Since the production efficiency of mold casting and semi-continuous casting is far lower than that of continuous casting, a considerable part of steel products has been converted from mold casting and semi-continuous casting to continuous casting production. However, after the conversion to continuous casting production, cracks in the process of bending and straightening become a major problem to be solved.

[0003] On the continuous casting production line, molten steel is vertically cast into the final horizontal transmission billet, so that the continuous casting billet must pass through the arc segment in this process. The continuous casting billet will be bent and straightened twice when it enters the arc segment from the vertical segment and when it enters the horizontal segment from the arc segment. In terms of the overall temperature distribution of the billet, the surface temperature of the billet is low and the core temperature is high during the two bending and straightening processes. Moreover, the billet is in two different time stages during the two bending and straightening processes, so the state and form of the billet are not the same. When the billet enters the bending segment from the vertical segment, the overall temperature of the billet is relatively high, the thickness of the billet shell is thin, and the proportion of molten steel in the cross section of the billet is large. When the billet enters the horizontal segment from the bending segment, the overall temperature of the billet is low, and due to the continuous solidification of the molten steel, the thickness of the billet shell increases and the proportion of molten steel in the cross section of the billet decreases. In addition, the slower the casting speed (the larger the cross-sectional size of the billet and the slower the casting speed when the production capacity is certain), the lower the overall temperature of the billet and the thicker the thickness of the billet shell at this stage. During the continuous casting stage, the temperature of the billet continuously decreases and the thickness of the billet shell continuously increases from the front segment to the end segment of the continuous casting line, until the center molten steel is completely solidified to form a full solid billet. Before the bending and straightening of the billet, on the one hand, a certain thickness of the billet shell is required to prevent the leakage of molten steel and cause serious safety accidents due to the excessively thin billet shell during the bending and straightening process; on the other hand, the thickness of the billet shell is too thick and the temperature of the billet is too low, which leads to a large force required for bending and straightening, and larger power mechanical equipment needs to be equipped. When the thickness of the billet shell is thick and the temperature is low, the billet surface is prone to cracking and other defects due to insufficient plasticity of the billet during the bending and straightening process.

[0004] Since the 21st century, with the rapid development of domestic wind power, high-speed rail, engineering machinery and other industries, the demand for raw materials has put forward higher requirements for scale, large-scale and high-end. The demand for large-section billets with larger size, more reliable quality and more stable performance is increasing in the market (such as wind power flanges). During the production of large-section billets, the casting speed of the billet is slower, the thickness of the billet shell before bending and straightening is thicker, and the deformation is larger, which is more likely to cause surface cracking of the billet.

[0005] In the present stage of continuous casting technology, the main means of temperature control in the production of casting blanks is full water cooling, gas mist cooling or natural cooling, in addition, the casting blank is kept warm with a heat preservation cover, there is no method and equipment for temperature compensation, and the traditional temperature compensation equipment cannot be arranged on the production line. Such temperature control means has the following defects:

[0006] On the one hand, although the thickness of the blank shell and the temperature of the casting blank (reducing the surface temperature of the casting blank) can be ensured by adjusting the amount of cooling medium, but the temperature control precision is low; on the other hand, when producing different steel grades, different section specifications and different production processes, the control of the cooling medium needs to be adjusted constantly, the control is complex and difficult, and quality defects (such as cracks) often occur due to inaccurate control of the amount of cooling medium, it is difficult to ensure the production of casting blanks at different times, different steel grades and different production processes by controlling the amount of the same cooling medium.

[0007] Electromagnetic induction heating has a series of advantages such as fast heating speed, high production efficiency, less oxidation damage, high steel yield, accurate temperature control area, high temperature control precision, no fuel, no pollution, compact system and small floor area. With the promotion of green manufacturing and the implementation of "carbon peak" and "carbon neutral" two-carbon work, electromagnetic induction heating technology will become a trend due to its own advantages and matching with steel metallurgy. At present, only a few foreign steel enterprises use induction heating technology in steel blank bending and straightening, but this aspect is still in the blank stage in China. SUMMARY

[0008] The purpose of the present application is to provide a heating system for continuous casting blank deformation and a control method thereof, and a continuous casting machine, to solve the problem of low temperature control precision caused by adjusting the cooling medium to ensure the temperature of the casting blank during the production of the casting blank, which in turn leads to cracks during the deformation of the casting blank.

[0009] The present application solves the above technical problems by the following technical solutions: a heating system for continuous casting blank deformation applied to a continuous casting machine, the model curve of the continuous casting machine includes a vertical section, a bending section, a circular arc section and a straightening section in sequence, and the heating system comprises:

[0010] A first induction heating unit arranged at the end of the vertical section or the front end of the bending section, the first induction heating unit is used for heating before the casting blank enters the bending section from the vertical section;

[0011] A second induction heating unit arranged at the end of the circular arc section or the front end of the straightening section, the second induction heating unit is used for heating before the casting blank enters the straightening section from the circular arc section;

[0012] a first power supply device for supplying power to the first induction heating unit, power modules in the first power supply device corresponding to the induction heaters in the first induction heating unit one by one;

[0013] a second power supply device for supplying power to the second induction heating unit, power modules in the second power supply device corresponding to the induction heaters in the second induction heating unit one by one;

[0014] a first temperature detection unit arranged at the front end of the first induction heating unit and used for detecting the temperature of the cast blank before entering the bending section;

[0015] a second temperature detection unit arranged at the front end of the second induction heating unit and used for detecting the temperature of the cast blank before entering the straightening section;

[0016] a control device connected with the first power supply device, the second power supply device, the first temperature detection unit and the second temperature detection unit respectively, the control device being used for controlling the first induction heating unit to be turned on according to the steel grade information of the cast blank, controlling the operating power of the first induction heating unit through the first power supply device according to the temperature detected by the first temperature detection unit and the first target temperature, and controlling the operating power of the second induction heating unit through the second power supply device according to the temperature detected by the second temperature detection unit and the second target temperature;

[0017] wherein the front end of the first induction heating unit refers to one end close to the vertical section, and the front end of the second induction heating unit refers to one end close to the circular arc section.

[0018] In the present application, the first temperature detection unit is used to detect the temperature of the cast blank before entering the bending section, the operating power or heating power of the first induction heating unit is controlled according to the temperature and the first target temperature, so that the cast blank does not crack or have cracks in this deformation stage, and the first target temperature is the temperature required for the cast blank to not crack or have cracks in this deformation stage; the second temperature detection unit is used to detect the temperature of the cast blank before entering the straightening section, the operating power or heating power of the second induction heating unit is controlled according to the temperature and the second target temperature, so that the cast blank does not crack or have cracks in this deformation stage, and the second target temperature is the temperature required for the cast blank to not crack or have cracks in this deformation stage. The present application can realize accurate control of the heating temperature of different steels and different positions, greatly improve the temperature control precision, avoid the problem of shell crack of the cast blank in the deformation process, and at the same time ensure the effective use of electric energy and save the heating cost.

[0019] Further, the second induction heating unit includes N induction heaters, the widths of the N induction heaters gradually increase from small to large, wherein the first induction heater is close to the circular arc section and has the smallest width, and the Nth induction heater is close to the straightening section and has the largest width.

[0020] Preferably, the width of the induction heater in the first induction heating unit is less than the width of the first induction heater in the second induction heating unit.

[0021] Further, the second temperature detection unit comprises N temperature sensors, the N temperature sensors correspond to the N induction heaters in the second induction heating unit one by one, and each temperature sensor is arranged at the front end of the corresponding induction heater.

[0022] The control device is further used for controlling the operating power of the corresponding induction heater in the second induction heating unit according to the second target temperature and the temperature detected by each temperature sensor.

[0023] Further, the induction heating system further comprises a cooling water device, the cooling water device comprises a plurality of cooling units, the number of the cooling units is equal to the sum of the number of the induction heaters in the first induction heating unit and the second induction heating unit and the number of the power modules in the first power device and the second power device, and the cooling units are used for cooling the corresponding induction heaters or power modules.

[0024] Based on the same inventive concept, the present application further provides a control method of the continuous casting billet deformation heating system, comprising the following steps:

[0025] Obtaining the steel grade information of the continuous casting billet and the temperature detected by the first temperature detection unit and the second temperature detection unit;

[0026] Controlling the first induction heating unit to be turned on according to the steel grade information of the continuous casting billet, and controlling the operating power of the first induction heating unit through the first power device according to the temperature detected by the first temperature detection unit and the first target temperature;

[0027] Controlling the operating power of the second induction heating unit through the second power device according to the temperature detected by the second temperature detection unit and the second target temperature.

[0028] Further, the calculation formula of the operating power of the first induction heating unit or the second induction heating unit is as follows:

[0029]

[0030] Wherein, P is the running power or heating power of the first or second induction heating unit; C is the specific heat capacity of the casting blank; m is the casting blank mass delivered in unit time, which only refers to the casting blank mass of the skin depth part of the induction current generated by the first or second induction heating unit; ΔT is the difference between the target temperature and the initial temperature, the target temperature is the first or second target temperature, and the initial temperature is the temperature detected by the first or second temperature detection unit; η is the heating efficiency; and ε is the skin depth coefficient.

[0031] Further, the specific process of sequentially controlling the running power of the N induction heaters in the second induction heating unit is as follows:

[0032] When the second target temperature T 2m is greater than the temperature T 21 detected by the first temperature sensor by the temperature that can be raised by full-power running of the first induction heater, the first induction heater runs at full power; when the second target temperature T 2m is less than or equal to the temperature T 21 detected by the first temperature sensor by the temperature that can be raised by full-power running of the first induction heater, the first induction heater runs at the power required to heat the casting blank from the temperature T 21 to the second target temperature T 2m .

[0033] When the second target temperature T 2m is greater than the temperature T 22 detected by the second temperature sensor by the temperature that can be raised by full-power running of the second induction heater, the second induction heater runs at full power; when the second target temperature T 2m is less than or equal to the temperature T 22 detected by the second temperature sensor by the temperature that can be raised by full-power running of the second induction heater, the second induction heater runs at the power required to heat the casting blank from the temperature T 22 to the second target temperature T 2m .

[0034] By analogy, when the second target temperature T 2m is greater than the temperature T 2i detected by the i-th temperature sensor by the temperature that can be raised by full-power running of the i-th induction heater, the i-th induction heater runs at full power, until the second target temperature T 2m is less than or equal to the temperature T 2i detected by the i-th temperature sensor by the temperature that can be raised by full-power running of the i-th induction heater; when the second target temperature T 2m is less than or equal to the temperature T 2iwhen the temperature of the casting blank is less than or equal to the temperature that can be raised by the i th induction heater operating at full power, the i th induction heater operates at a power that raises the temperature of the casting blank from T 2i to a second target temperature T 2m ;

[0035] wherein the first induction heater refers to the induction heater close to the circular arc segment.

[0036] Further, when the n induction heaters cause the temperature of the casting blank to reach the second target temperature T 2m , and n < N, the (n+1) th to (N-1) th induction heaters are controlled to be inoperative, and the N th induction heater is controlled to perform temperature compensation on the casting blank.

[0037] Further, the control method further comprises:

[0038] obtaining the inlet and outlet water temperatures of each cooling unit, and the power of each induction heater or each power module;

[0039] controlling the inlet and outlet water flow rates of the cooling unit according to the inlet and outlet water temperatures of the cooling unit and the power of the corresponding induction heater or power module, and the specific control formula is:

[0040] P w (1-η w )·ζ=C 水 m 水 (T 出 -T 进 )

[0041] wherein P w is the power of the induction heater or the power module; η w is the heating efficiency or the power supply efficiency; ζ is the safety factor; C 水 is the specific heat capacity of water, m 水 is the water flow rate per unit time; T 出 is the outlet water temperature of the cooling unit; and T 进 is the inlet water temperature of the cooling unit.

[0042] Based on the same inventive concept, the application also provides a continuous casting machine, which comprises the heating system for continuous casting blank deformation as described above.

[0043] Advantages

[0044] Compared with the prior art, the application has the following advantages:

[0045] The heating system for continuous casting billet deformation and its control method and continuous casting machine provided by the application detect the temperature of the billet before entering the bending section by using a first temperature detecting unit, control the operating power or heating power of the first induction heating unit according to the temperature and a first target temperature, so that the billet does not crack or have cracks in the deformation stage, and the first target temperature is the temperature required for the billet not to crack or have cracks in the deformation stage; the temperature of the billet before entering the straightening section is detected by using a second temperature detecting unit, the operating power or heating power of the second induction heating unit is controlled according to the temperature and a second target temperature, so that the billet does not crack or have cracks in the deformation stage, and the second target temperature is the temperature required for the billet not to crack or have cracks in the deformation stage.

[0046] The application can realize accurate control of the heating temperature of different steel types and different positions, greatly improve the temperature control accuracy, avoid the billet shell crack problem in the deformation process, and ensure effective use of electric energy and saving of heating cost. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the application, the drawings needed in the following embodiment description will be briefly introduced. Obviously, the drawings in the following description are only one embodiment of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0048] Figure 1 Fig. 1 is a structure schematic diagram of the heating system for continuous casting billet deformation in the embodiment of the application;

[0049] Figure 2 Fig. 2 is a layout diagram of the first induction heating unit and the second induction heating unit on the machine type curve in the embodiment of the application;

[0050] Figure 3 Fig. 3 is a control circuit diagram of the heating system for continuous casting billet deformation in the embodiment of the application, in which the double-dot dashed line is a control line, and the dashed line is a power cable;

[0051] Figure 4 Fig. 4 is a schematic diagram of the mass m of the billet conveyed in unit time in the embodiment of the application;

[0052] Figure 5 Fig. 5 is a structure schematic diagram of the induction heater in the embodiment of the application;

[0053] Fig. 6(a) is a front view of the induction heater in the embodiment of the application;

[0054] Fig. 6(b) is a side view of the induction heater in the embodiment of the application;

[0055] Fig. 6(c) is a top view of the induction heater in the embodiment of the application;

[0056] Figure 7 is the structure diagram of the induction coil of the induction heater in the embodiment of the present application;

[0057] Figure 8 is the control flow chart of the heating system for the deformation of the continuous casting billet in the embodiment of the present application.

[0058] Wherein, 1-first power supply device, 2-control device, 3-second temperature detection unit, 4-second power supply device, 5-cooling water device, 6-second induction heating unit, 61-first induction heater in the second induction heating unit, 611-annular shell, 612-first power supply bus / second power supply bus, 613-insulating plate, 614-water inlet box / water outlet box, 615-pouring material, 616-induction coil, 7-casting billet, 8-first induction heating unit, 81-induction heater in the first induction heating unit. DETAILED DESCRIPTION

[0059] The technical solutions in the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work belong to the scope of protection of the present application.

[0060] The technical solutions of the present application will be described in detail in combination with specific embodiments. The following specific embodiments can be combined with each other, and some embodiments may not be described again for the same or similar concepts or processes.

[0061] In the production process of continuous casting billets, the billet enters the curved section from the initial vertical section, and then enters the horizontal section from the curved section. In the two connection stages, the billet must be plastically deformed to ensure that the billet is turned from the vertical direction to the horizontal direction. When the vertical section enters the curved section, the temperature of the billet is relatively high, and the plasticity is good, so the billet is easy to bend. However, for some steel grades with extremely high crack sensitivity, surface cracking or cracks are prone to occur in this stage. When the billet enters the horizontal section from the curved section, the temperature of the billet is relatively low, and the plasticity is poor, so the required straightening mechanical force is larger. The most difficult to avoid is the surface cracking or cracking of the billet during the straightening process, especially when producing large-section billets, the possibility of surface cracking is larger and the frequency is higher.

[0062] At present, in the continuous casting production process, the bending deformation and straightening temperature control of the casting blank mainly adopts water cooling, air mist cooling, air natural cooling and related heat preservation device (heat preservation cover) heat preservation, without any heating, heating method and equipment. The total water quantity control requirement is high when using water cooling method, the water quantity directly acting on the casting blank and playing a cooling role cannot be controlled at each point, precise temperature control cannot be achieved, and the original temperature control is also affected by the environment temperature, the cooling medium quantity and related production process need to be adjusted according to the environment temperature, the operation is complex and uncontrollable.

[0063] Based on the above technical problems, as shown in Figures 1-3 A heating system for continuous casting blank deformation is provided, wherein the model curve of the continuous casting machine comprises a vertical section, a curved section, an arc section and a straightening section in sequence, and the heating system comprises a first induction heating unit 8, a second induction heating unit 6, a first power supply device 1, a second power supply device 4, a first temperature detection unit, a second temperature detection unit 3 and a control device 2. Figure 2 The first power supply device 1 is connected with the first induction heating unit 8, the second power supply device 4 is connected with the second induction heating unit 6, and the control device 2 is connected with the first power supply device 1, the second power supply device 4, the first temperature detection unit and the second temperature detection unit 3.

[0064] The first induction heating unit 8 is arranged at the end of the vertical section or the front end of the curved section, and is used for heating the casting blank before entering the curved section from the vertical section. Since the overall temperature of the casting blank at the end of the vertical section or the front end of the curved section is high, and the shell is thin, the first induction heating unit 8 is mainly used for heating the crack-sensitive steel grade, and a smaller number of induction heaters can be used. The second induction heating unit 6 is arranged at the end of the arc section or the front end of the straightening section, and is used for heating the casting blank before entering the straightening section from the arc section. Since the overall temperature of the casting blank at the end of the arc section or the front end of the straightening section is low, and the shell thickness becomes thicker as it approaches the end of the arc section, one, two or more induction heaters of different sizes or the same size can be matched according to the different casting blank steel grades.

[0065] In this embodiment, the first induction heating unit 8 includes one induction heater, and the second induction heating unit 6 includes N induction heaters (N=4).

[0066] The first power supply device 1 is used to supply power to the first induction heating unit 8, and the second power supply device 4 is used to supply power to the second induction heating unit 6. In order to independently supply power to the induction heaters in the first induction heating unit 8 and the second induction heating unit 6, the first power supply device 1 contains the same number of power supply modules as the number of induction heaters in the first induction heating unit 8, and the second power supply device 4 contains the same number of power supply modules as the number of induction heaters in the second induction heating unit 6. In this embodiment, the first power supply device 1 contains one power supply module (corresponding to one induction heater in the first induction heating unit), and the second power supply device 4 contains N power supply modules (corresponding to N induction heaters in the second induction heating unit), and each power supply module independently supplies power to the corresponding induction heater.

[0067] The first temperature detection unit is arranged at the front end of the first induction heating unit 8 and is used to detect the temperature of the cast blank before entering the bending section, and the second temperature detection unit 3 is arranged at the front end of the second induction heating unit 6 and is used to detect the temperature of the cast blank before entering the straightening section. The control device 2 controls the first induction heating unit 8 to be turned on according to the steel grade information of the cast blank, controls the operating power of the first induction heating unit 8 through the first power supply device 1 according to the temperature detected by the first temperature detection unit and the first target temperature, and controls the operating power of the second induction heating unit 6 through the second power supply device 4 according to the temperature detected by the second temperature detection unit 3 and the second target temperature.

[0068] The front end of the first induction heating unit 8 refers to the end close to the vertical section, and the front end of the second induction heating unit 6 refers to the end close to the circular arc section. The first target temperature is the temperature required for the cast blank to not crack or crack in the first deformation stage (vertical to bending deformation stage), and the second target temperature is the temperature required for the cast blank to not crack or crack in the second deformation stage (circular arc to straightening deformation stage).

[0069] When the cast blank is a crack-sensitive steel grade or the temperature of the cast blank is too low to reach the target temperature of deformation without cracking, the first induction heating unit 8 needs to be heated, and the first induction heating unit 8 does not need to be heated in other cases. Regardless of the steel grade, the second induction heating unit 6 needs to be heated, but the heating power required is different for different cast blank temperatures. In this embodiment, the calculation formula of the operating power of the first induction heating unit 8 or the second induction heating unit 6 is:

[0070]

[0071] Wherein, P is the operating power or heating power of the first induction heating unit 8 or the second induction heating unit 6; C is the specific heat capacity of the billet; m is the mass of the billet transferred per unit time, which refers only to the mass of the billet in the skin depth portion of the induced current generated by the first induction heating unit 8 or the second induction heating unit 6; ΔT is the difference between the target temperature and the initial temperature, where the target temperature is the first target temperature or the second target temperature, and the initial temperature is the temperature detected by the first temperature detection unit or the second temperature detection unit 3; η is the heating efficiency; and ε is the skin depth coefficient.

[0072] For example, if P is the operating power or heating power of the second induction heating unit 6, then ΔT is the difference between the second target temperature and the temperature detected by the second temperature detection unit 3. The second induction heating unit 6 includes N induction heaters, and the temperature detected by the second temperature detection unit 3 is the temperature at the front end of the first induction heater 61 in the second induction heating unit 6. Then P is the sum of the operating power or heating power of the N induction heaters.

[0073] m represents the mass of the cast billet transmitted per unit time. This mass refers only to the mass of the cast billet within the skin depth portion of the induced current generated by the first induction heating unit 8 or the second induction heating unit 6. Figure 4 The black filled portion shown represents the billet outer diameter (H1), the molten steel region outer diameter (H2), and the billet shell thickness (δ). m is related to the billet casting speed, which in turn is related to the width of the induction heater, i.e., L = νt, where L is the width of the induction heater, ν is the billet casting speed (the speed at which the billet moves within the induction heater), and t is the heating time within the corresponding induction heater. Higher temperatures, faster casting speeds, a greater number of induction heaters operating in the second induction heating unit 6, higher heating power, and larger induction heater widths are all required.

[0074] The number of temperature sensors in the first temperature detection unit is the same as the number of induction heaters in the first induction heating unit 8, and the number of temperature sensors in the second temperature detection unit 3 is the same as the number of induction heaters in the second induction heating unit 6. In this embodiment, if the number of induction heaters in the first induction heating unit 8 is 1, then the number of temperature sensors in the first temperature detection unit is 1; if the number of induction heaters in the second induction heating unit 6 is N, then the number of temperature sensors in the second temperature detection unit 3 is N. Each temperature sensor is located at the front end of the corresponding induction heater.

[0075] The full power or rated power of the induction heater in the first induction heating unit 8 should be greater than or equal to the power required to heat the casting blank from the temperature detected by the first temperature detection unit to the first target temperature; the sum of the full power or rated power of the N induction heaters in the second induction heating unit 6 should be greater than or equal to the power required to heat the casting blank from the temperature detected by the first temperature sensor in the second temperature detection unit 3 to the second target temperature. The control device 2 can also control the operating power of the corresponding induction heater in the second induction heating unit 6 according to the second target temperature and the temperature detected by each temperature sensor in the second temperature detection unit 3.

[0076] The closer to the solidification end of the casting blank, the thicker the shell thickness and the lower the casting blank temperature, in order to ensure the heating power or operating power of the induction heater and the heating time of the casting blank, the closer to the solidification end of the casting blank, the greater the width of the induction heater, that is, the closer to the solidification end, the more the number of turns of the induction coil of the induction heater, and vice versa, the farther away from the solidification end, the fewer the number of turns of the induction coil of the induction heater. As shown in Figure 1 The width of the N induction heaters in the second induction heating unit 6 is shown in order from small to large, wherein the first induction heater 61 is close to the circular arc segment and has the smallest width, and the Nth induction heater is close to the straightening segment and has the largest width; the width of the induction heater 81 in the first induction heating unit 8 is smaller than the width of the first induction heater 61 in the second induction heating unit 6. The solidification end of the casting blank refers to the position where the molten steel in the center of the cross section is solidified into a solid state during the production of the casting blank. The width of the induction heater refers to the axial length of the induction coil, that is, the length of the casting blank in the induction heater during the conveying process of the casting blank.

[0077] The fewer the number of turns of the induction coil of the induction heater, the higher the frequency output at the required power, and the higher the frequency can ensure that the induction current with a shallower skin depth can heat the shell, better adapt to the thinner shell thickness, and reduce or avoid the influence of eddy current heat on the temperature of the molten steel, further avoiding the crack problem.

[0078] In one specific embodiment of the present application, the induction heating system further comprises a cooling water device 5, the cooling water device 5 comprising a plurality of cooling units, the number of cooling units being equal to the sum of the number of induction heaters in the first induction heating unit 8 and the second induction heating unit 6, and the number of power modules in the first power supply device 1 and the second power supply device 4, the cooling unit being used to cool the corresponding induction heater or power module.

[0079] In this embodiment, the first induction heating unit 8 includes one induction heater, the second induction heating unit 6 includes N induction heaters, the first power supply device 1 includes one power module, and the second power supply device 4 includes N power modules. Therefore, the number of cooling units is 2N+2. In this embodiment, the control device 2 controls the inlet and outlet water flow rates of the cooling unit based on the inlet and outlet water temperatures and the power of the corresponding induction heaters or power modules. The specific control formula is as follows:

[0080] P w (1-η w )·ζ=C 水 m 水 (T 出 -T 进 (2)

[0081] Among them, P w The power of the induction heater or power module; η w For heating efficiency or power supply efficiency; ζ is the safety factor; C 水 m is the specific heat capacity of water. 水 T is the water flow rate per unit time. 出 T represents the outlet water temperature of the cooling unit. 进 This refers to the inlet water temperature of the cooling unit.

[0082] Control device 2 monitors and adjusts the temperature at the front end of each induction heater and the water flow rate of the corresponding cooling unit. It also compares the sum of the water flow rates of each cooling unit with the total water output of the cooling water system to determine the water leakage situation. Control device 2 adjusts the water supply of each cooling unit based on the outlet water temperature of each unit. When the outlet water temperature is too high, the pump speed is increased and the water pressure is increased, thereby increasing the water flow rate. When the outlet water temperature is too low, the pump speed is reduced and the water supply pressure is reduced, thereby reducing the water flow rate. In this way, it ensures that each power module and induction heater that needs to be cooled operates within the normal temperature range.

[0083] like Figures 5-7As shown, each induction heater comprises a ring-shaped shell 611, an induction coil 616 arranged in the ring-shaped shell 611, a first power supply copper bar and a second power supply copper bar 612 connected to both ends of the induction coil 616, and an insulating plate 613 arranged between the first power supply copper bar and the second power supply copper bar. The induction coil has a spiral structure, and its inlet and outlet ends are led out through the first power supply copper bar and the second power supply copper bar for external power supply; the insulating plate 613 ensures the insulation between the first power supply copper bar and the second power supply copper bar; the induction coil 616 is fixed to the ring-shaped shell 611 through casting material 615, and the casting material 615 also serves the purpose of insulating the induction coil 616 from the ring-shaped shell 611. Water inlet box and water outlet box 614 are also arranged on the ring-shaped shell 611, and water pipes and joints are welded on the water inlet box and the water outlet box 614 for easy connection with corresponding cooling units to ensure the water cooling of the induction coil 616. Figure 6a In the formula, H is the width of the induction heater.

[0084] Based on the same inventive concept, as Figure 8 shown, the embodiment of the present application also provides a control method of the heating system for continuous casting billet deformation as described above, comprising the following steps:

[0085] Step 1: obtaining the steel grade information of the continuous casting billet, and the temperatures detected by the first temperature detection unit and the second temperature detection unit;

[0086] Step 2: controlling the first induction heating unit to be turned on according to the steel grade information of the continuous casting billet, and controlling the operating power of the first induction heating unit through the first power supply device according to the temperature detected by the first temperature detection unit and the first target temperature;

[0087] Step 3: controlling the operating power of the second induction heating unit through the second power supply device according to the temperature detected by the second temperature detection unit and the second target temperature.

[0088] When the continuous casting billet is a crack-sensitive steel grade or the temperature of the continuous casting billet is too low to reach the target temperature of deformation without cracking, the first induction heating unit needs to be heated, and the first induction heating unit does not need to be heated in other cases; regardless of the steel grade, the second induction heating unit needs to be heated, and only the heating power required for different continuous casting billet temperatures is different. In this embodiment, the operating power of the first induction heating unit or the second induction heating unit is calculated according to the formula (1) shown below.

[0089] The number of temperature sensors in the first temperature detection unit is the same as the number of induction heaters in the first induction heating unit, and the number of temperature sensors in the second temperature detection unit is the same as the number of induction heaters in the second induction heating unit. In the embodiment, the number of induction heaters in the first induction heating unit is 1, and the number of temperature sensors in the first temperature detection unit is 1; the number of induction heaters in the second induction heating unit is N, and the number of temperature sensors in the second temperature detection unit is N. Each temperature sensor is arranged at the front end of the corresponding induction heater.

[0090] The full power or rated power of the induction heater in the first induction heating unit should be greater than or equal to the power required to heat the casting blank from the temperature detected by the first temperature detection unit to the first target temperature; the sum of the full power or rated power of the N induction heaters in the second induction heating unit should be greater than or equal to the power required to heat the casting blank from the temperature detected by the first temperature sensor in the second temperature detection unit to the second target temperature. The control device controls the operating power of the corresponding induction heater in the second induction heating unit according to the second target temperature and the temperature detected by each temperature sensor in the second temperature detection unit.

[0091] In the embodiment, the specific process of controlling the operating power of the N induction heaters in the second induction heating unit in turn is as follows:

[0092] When the second target temperature T 2m is greater than the temperature T 21 detected by the first temperature sensor, and the difference is greater than the temperature that can be raised by full power operation of the first induction heater, it indicates that even if the first induction heater is operated at full power, the temperature of the casting blank cannot be raised from T 21 to the second target temperature T 2m Therefore, the first induction heater is controlled to operate at full power.

[0093] When the second target temperature T 2m is greater than the temperature T 21 detected by the first temperature sensor, and the difference is less than or equal to the temperature that can be raised by full power operation of the first induction heater, it indicates that even if the first induction heater is operated at full power or below full power, the temperature of the casting blank can be raised from T 21 to the second target temperature T 2m Therefore, the first induction heater is controlled to operate at a power required to heat the casting blank from the temperature T 21 to the second target temperature T 2m At this time, the first induction heater can raise the temperature of the casting blank from T 21 to the second target temperature T 2m , and the second to Nth induction heaters are not working. In this case, the first induction heater is operated at full power or below full power (adapted power).

[0094] When the second target temperature T 2m is greater than the temperature T 22 determined by the second temperature sensor by an amount greater than the temperature that can be raised by the second induction heater operating at full power, it is indicated that even if the second induction heater is operated at full power, the temperature of the casting blank cannot be raised from T 22 to the second target temperature T 2m Therefore, the second induction heater is controlled to operate at full power. In this case, both the first induction heater and the second induction heater are operated at full power.

[0095] When the second target temperature T 2m is less than or equal to the temperature T 22 determined by the second temperature sensor by an amount less than or equal to the temperature that can be raised by the second induction heater operating at full power, it is indicated that the temperature of the casting blank can be raised from T 22 to the second target temperature T 2m Therefore, the second induction heater is controlled to operate at a power required to raise the temperature of the casting blank from T 22 to the second target temperature T 2m In this case, the first induction heater and the second induction heater can raise the temperature of the casting blank from T 21 to the second target temperature T 2m , the third induction heater to the Nth induction heater are not operated. In this case, the first induction heater is operated at full power, and the second induction heater is operated at full power or at a power lower than full power (adapted power).

[0096] By analogy, when the second target temperature T 2m is greater than the temperature T 2i determined by the i-th temperature sensor by an amount greater than the temperature that can be raised by the i-th induction heater operating at full power, the i-th induction heater is operated at full power until the second target temperature T 2m is less than or equal to the temperature T 2i determined by the i-th temperature sensor by an amount less than or equal to the temperature that can be raised by the i-th induction heater operating at full power (i.e., the first i induction heaters can meet the requirement of raising the temperature of the casting blank to the second target temperature). In this case, the first induction heater to the i-th induction heater are operated at full power.

[0097] When the second target temperature T 2m is less than or equal to the temperature T 2i determined by the i-th temperature sensor by an amount less than or equal to the temperature that can be raised by the i-th induction heater operating at full power, the i-th induction heater is controlled to operate at a power required to raise the temperature of the casting blank from T 2i to the second target temperature T 2mWhen the casting billet is heated to the second target temperature, the first to the i-th induction heater is in full power operation, and the i+1-th to the N-th induction heater is not in operation. In this case, the first to the i-1-th induction heater is in full power operation, and the i-th induction heater is in full power operation or in operation below full power (adapted power).

[0098] When the casting billet has a high incoming temperature, the first to the n-th induction heater (n 2m < N) can heat the casting billet to the second target temperature, but the casting billet temperature is lower than the second target temperature due to temperature drop during conveying to the designated position (without heating), so temperature compensation is needed. In the embodiment, when the n-th induction heater makes the casting billet temperature reach the second target temperature T 2m , and n

[0099] In the embodiment, the specific value of the temperature compensation can be obtained from the temperature compensation database, and the specific construction of the temperature compensation database is as follows: when the environment temperature is T h , the temperature drop of the casting billet from the n-th induction heater to the designated position is ΔT nN ; the temperature drop of the casting billet from different induction heaters to the designated position under different environment temperatures is obtained by measurement and stored in the control device. The control device controls the corresponding power module in the second power supply device according to different conditions, so that the N-th induction heater outputs adapted power to compensate for the temperature drop of the casting billet without heating, and ensures that the casting billet reaches the second target temperature again when conveying to the designated position, i.e. the target temperature before straightening.

[0100] In a specific embodiment of the present application, the control method further comprises:

[0101] obtaining the inlet and outlet water temperature of each cooling unit, and the power of each induction heater or each power module;

[0102] controlling the inlet and outlet water flow of the cooling unit according to the inlet and outlet water temperature of the cooling unit and the power of the corresponding induction heater or power module, and the specific control formula is shown in formula (2).

[0103] The above only discloses specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or modifications within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A heating system for shape change of a continuous casting billet, which is applied to a continuous casting machine, a machine profile curve of the continuous casting machine successively including a vertical section, a curved section, a circular arc section, and a straightening section, characterized in that, The heating system comprises: a first induction heating unit arranged at the end of the vertical section or the front end of the curved section, the first induction heating unit being used for heating the cast slab before entering the curved section from the vertical section; a second induction heating unit arranged at the end of the arc section or the front end of the straightening section, the second induction heating unit being used for heating the cast slab before entering the straightening section from the arc section; a first power supply device for supplying power to the first induction heating unit, the power supply modules in the first power supply device corresponding to the induction heaters in the first induction heating unit one by one; a second power supply device for supplying power to the second induction heating unit, the power supply modules in the second power supply device corresponding to the induction heaters in the second induction heating unit one by one; a first temperature detection unit arranged at the front end of the first induction heating unit and used for detecting the temperature of the cast slab before entering the curved section; a second temperature detection unit arranged at the front end of the second induction heating unit and used for detecting the temperature of the cast slab before entering the straightening section; a control device connected with the first power supply device, the second power supply device, the first temperature detection unit and the second temperature detection unit respectively, the control device being used for controlling the first induction heating unit to be turned on according to the steel grade information of the cast slab, controlling the running power of the first induction heating unit through the first power supply device according to the temperature detected by the first temperature detection unit and the first target temperature, and controlling the running power of the second induction heating unit through the second power supply device according to the temperature detected by the second temperature detection unit and the second target temperature; wherein the front end of the first induction heating unit refers to one end close to the vertical section, and the front end of the second induction heating unit refers to one end close to the arc section.

2. The heating system for shape change of a continuous cast billet according to claim 1, characterized by: The second induction heating unit comprises N induction heaters, the widths of the N induction heaters gradually increase from small to large, wherein the first induction heater is close to the arc section and has the smallest width, and the Nth induction heater is close to the straightening section and has the largest width. Preferably, the width of the induction heater in the first induction heating unit is smaller than the width of the first induction heater in the second induction heating unit.

3. The heating system for shape change of a continuous cast billet according to claim 1, characterized by: The second temperature detection unit comprises N temperature sensors, the N temperature sensors correspond to the N induction heaters in the second induction heating unit one by one, and each temperature sensor is arranged at the front end of the corresponding induction heater. The control device is further used for controlling the running power of the corresponding induction heater in the second induction heating unit according to the second target temperature and the temperature detected by each temperature sensor.

4. The heating system for shape change of a continuous cast billet according to any one of claims 1 to 3, characterized by: The induction heating system further comprises a cooling water device, the cooling water device comprises a plurality of cooling units, the number of the cooling units being equal to the sum of the number of the induction heaters in the first induction heating unit and the second induction heating unit and the number of the power supply modules in the first power supply device and the second power supply device, and the cooling units are used for cooling the corresponding induction heaters or power supply modules. The method comprises the following steps:

5. A method of controlling a heating system for shape change of a continuous casting billet as claimed in any one of claims 1 to 4, characterized by, obtaining the steel grade information of the cast slab and the temperatures detected by the first temperature detection unit and the second temperature detection unit; ​ The first induction heating unit is controlled to be turned on according to the steel grade information of the casting blank, and the operating power of the first induction heating unit is controlled by the first power supply device according to the temperature detected by the first temperature detection unit and the first target temperature; The operating power of the second induction heating unit is controlled by the second power supply device according to the temperature detected by the second temperature detection unit and the second target temperature.

6. The method of controlling a continuous casting billet heating system according to claim 5, wherein The calculation formula of the operating power of the first induction heating unit or the second induction heating unit is: Wherein, P is the operating power or heating power of the first induction heating unit or the second induction heating unit; C is the specific heat capacity of the casting blank; m is the mass of the casting blank conveyed in unit time, which only refers to the mass of the casting blank in the skin depth part of the induction current generated by the first induction heating unit or the second induction heating unit; ΔT is the difference between the target temperature and the initial temperature, the target temperature is the first target temperature or the second target temperature, and the initial temperature is the temperature detected by the first temperature detection unit or the temperature detected by the second temperature detection unit; η is the heating efficiency; and ε is the skin depth coefficient.

7. The method of controlling a continuous casting billet heating system according to claim 5, wherein The specific process of sequentially controlling the operating power of the N induction heaters in the second induction heating unit is: When the second target temperature T 2m is greater than the temperature T 21 detected by the first temperature sensor by an amount greater than the temperature increase that can be achieved by operating the first induction heater at full power, the first induction heater is operated at full power; when the second target temperature T 2m is greater than the temperature T 21 detected by the first temperature sensor by an amount less than or equal to the temperature increase that can be achieved by operating the first induction heater at full power, the first induction heater is operated at a power level that will heat the cast slab from the temperature T 21 to the second target temperature T 2m . When the second target temperature T 2m is greater than the temperature T 22 detected by the second temperature sensor by more than the temperature that the second induction heater can raise at full power, the second induction heater is operated at full power; when the second target temperature T 2m is less than or equal to the temperature T 22 detected by the second temperature sensor, the second induction heater is operated at a power required to heat the cast blank from the temperature T 22 to the second target temperature T 2m . By analogy, when the second target temperature T 2m is greater than the temperature T 2i that the i th temperature sensor detects by more than the temperature that the i th induction heater can raise by running at full power, the i th induction heater runs at full power until the second target temperature T 2m is less than or equal to the temperature T 2i that the i th temperature sensor detects; when the second target temperature T 2m is less than or equal to the temperature T 2i that the i th temperature sensor detects, the i th induction heater runs at the power required to heat the casting blank from the temperature T 2i to the second target temperature T 2m . Wherein, the first induction heater refers to the induction heater close to the circular arc segment.

8. The method of controlling a continuous casting billet heating system according to claim 7, wherein When the n number of induction heaters bring the temperature of the casting blank to the second target temperature T 2m , and n < N, the (n+1) to (N-1) induction heaters are controlled not to operate, and the Nth induction heater is controlled to perform temperature compensation on the casting blank.

9. The method of controlling a continuous casting billet deformation heating system according to any one of claims 5 to 8, characterized by, The control method further comprises: Obtaining the inlet and outlet water temperature of each cooling unit, the power of each induction heater or each power module; According to the inlet and outlet water temperature of the cooling unit and the power of the corresponding induction heater or power module, the inlet and outlet water flow of the cooling unit is controlled, and the specific control formula is: P w (1-η w )·ζ=C 水 m 水 (T 出 -T 进 ) where P w is the power of the induction heater or power module; η w is the heating efficiency or power supply efficiency; ζ is the safety factor; C 水 is the specific heat capacity of water, m 水 is the water flow rate per unit time; T 出 is the outlet water temperature of the cooling unit; T 进 is the inlet water temperature of the cooling unit.

10. A continuous caster characterized by: The continuous casting machine comprises the heating system for continuous casting blank deformation according to any one of claims 1-4.

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