A transverse and longitudinal magnetic alternating induction heating system and heating method

Abstract

The present invention provides an induction heating system and heating method with alternating transverse and longitudinal magnetic fields, defining a channel for a slab to pass through as a slab channel, and the induction heating system includes a first induction heating unit and a second induction heating unit arranged alternately in the running direction of the slab; the first induction heating unit includes K1 first inductors for generating a transverse magnetic field with a magnetic field direction perpendicular to the surface of the slab, thereby heating the slab located on the slab channel; the second induction heating unit includes K2 second inductors for generating a longitudinal magnetic field with a magnetic field direction parallel to the surface of the slab, thereby heating the slab located on the slab channel. The heating system with alternating transverse and longitudinal magnetic fields of the present invention can effectively reduce the temperature deviation between the corners and the surface of the slab.

Description

Technical Field

[0001] The invention belongs to the technical field of steel rolling, and in particular is an induction heating system and a heating method of alternating transverse and longitudinal magnetic fields. Background Art

[0002] In the continuous casting and rolling heat treatment process, induction heating technology has become the preferred technology for plate heat treatment process. It is widely used in: inlet temperature control before finishing or initial rolling, providing temperature basis for rolling of different specifications; used for local heating of slab corners, to supplement the low temperature caused by more serious edge heat loss due to the large width-to-thickness ratio of the slab, so as to reduce corner crack defects.

[0003] The principle of induction heating is to use the skin effect of alternating current to generate eddy currents on the surface of the ingot. From the heating principle, it is mainly divided into two heating methods: transverse and longitudinal magnetic flux. In longitudinal magnetic flux induction heating, the magnetic flux direction is parallel to the surface of the metal sheet. Its advantages are uniform heating and simple structure, and its disadvantages are low heating efficiency, high power supply operating frequency, and large loss of electronic components. The direction of the magnetic flux generated by the transverse magnetic flux sensor is perpendicular to the surface of the heated object, and the eddy currents induced in the slab are parallel to the surface of the plate. There is no problem of mutual cancellation of eddy currents on the cross section of the plate, so the heating efficiency is high and the energy utilization rate is high. However, the disadvantage of transverse magnetic flux induction heating is uneven heating, and eddy currents are easy to gather at the front end or edge of the metal plate and overburn.

[0004] Therefore, in the actual production process, in order to achieve the rolling temperature of the slab without quality defects such as corner cracks, the current processing technology is to first install a set of edge or corner heating systems to increase the temperature of the edges and corners to prevent corner cracks, such as CN106938324A; and then install several sets of induction heating systems to increase the rolling temperature, such as CN105698525A and CN106793226A. Using different induction heating systems to control the edge and corner temperature and rolling temperature at different locations not only has high equipment costs, but also makes equipment maintenance difficult and the coordination of multiple systems difficult. Summary of the invention

[0005] The problem to be solved by the present invention is that heating uniformity and heating efficiency cannot be taken into account in the existing slab induction heating, and an induction heating system and a heating method with alternating horizontal and vertical magnetic fields are provided.

[0006] In order to solve the problems of the prior art, the purpose of the present invention is to overcome the shortcomings of the existing technology and, for the heat treatment technology of continuous casting and rolling slabs, propose an induction heating system and process method of longitudinal and transverse magnetic alternation with compact equipment structure and simple operation.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: an induction heating system with alternating transverse and longitudinal magnetic fields, wherein a channel through which a slab passes is defined as a slab channel, and characterized in that the induction heating system comprises a first induction heating unit and a second induction heating unit which are alternately arranged in a running direction of the slab, and the induction heating unit arranged at the rear in the running direction of the slab is the first induction heating unit, and the number of the first induction heating unit and the number of the second induction heating unit are M1 and M2 respectively, M1≥2, M2≥2;

[0008] Each first induction heating unit includes K1 first inductors for generating a transverse magnetic field with a magnetic field direction perpendicular to the surface of the slab, so as to heat the slab located on the slab channel;

[0009] Each second induction heating unit includes K2 second inductors for generating a longitudinal magnetic field with a magnetic field direction parallel to the surface of the slab, thereby heating the slab located on the slab channel.

[0010] In the present invention, through the above arrangement, the first inductor has high transverse magnetic flux heating efficiency and the magnetic lines of force are easily gathered at the corners, so that the corner temperature can be greatly increased first to compensate for the heat dissipation at the corners before the slab enters the induction heating system, and then the second inductor of the longitudinal magnetic flux is used to uniformly heat the entire ingot, and then the temperature is further uniformed by the heat conduction of the slab itself. Similarly, the first induction heating unit and the second induction heating unit are alternately arranged in the running direction of the slab, so that the purpose of heating and equalizing the slab can be achieved.

[0011] Furthermore, each first inductor includes a first induction coil and a second induction coil which are arranged in pair and respectively located above and below the slab channel. The coil planes of the first induction coil and the coil planes of the second induction coil are arranged relatively to each other. When current is passed through the first induction coil and the second induction coil, a transverse magnetic field is generated with a magnetic field direction perpendicular to the surface of the slab, thereby heating the slab located on the slab channel.

[0012] In a preferred embodiment, the first induction coil and the second induction coil are in a ring shape or a U-shaped shape.

[0013] In a preferred embodiment, the coil planes of the first induction coil and the second induction coil are parallel to the cross section of the slab.

[0014] Furthermore, each second inductor includes a third induction coil having a middle opening, and the slab channel passes through the middle opening of the third induction coil. When current is passed through the third induction coil, a longitudinal magnetic field is generated with a magnetic field direction parallel to the slab surface, thereby heating the slab located on the slab channel.

[0015] In a preferred embodiment, the third induction coil is in a ring shape or a U-shaped shape.

[0016] In a preferred embodiment, the coil plane of the third induction coil is perpendicular to the running direction of the slab.

[0017] Furthermore, M1=M2, K1=K2.

[0018] In a preferred embodiment, M1=M2=2, K1=K2=4.

[0019] Further, the induction heating system also includes a controller, M1 first cooling systems, M2 second cooling systems, M1 first power supplies, and M2 second power supplies;

[0020] Each first cooling system, each second cooling system, each first power supply, and each second power supply are independently arranged;

[0021] The i-th first induction heating unit is powered by the i-th first power supply and cooled by the i-th first cooling system;

[0022] The j-th second induction heating unit is powered by the j-th second power supply and cooled by the j-th second cooling system;

[0023] i=1,2,…,M1, j=1,2,…,M2;

[0024] A first temperature measuring device for measuring the edge temperature of the slab is provided at the inlet position of each first induction heating unit, a second temperature measuring device for measuring the surface temperature of the slab is provided at the inlet position of each second induction heating unit, and a third temperature measuring device for measuring the surface temperature of the slab is provided at the outlet position of the slab passage, the edge temperature of the slab is the temperature of at least one side wall of the slab in the running direction of the slab, and the surface temperature of the slab is at least one of the upper surface temperature of the slab or the lower surface temperature of the slab;

[0025] Each first power supply, each second power supply, each first cooling system, each second cooling system, each first temperature measuring device, each second temperature measuring device, and the third temperature measuring device are all electrically connected to the controller.

[0026] In the present invention, each cooling system and each power supply are independently arranged, so that the heating power or cooling can be adjusted independently when the slab passes through.

[0027] Furthermore, the first induction heating unit arranged at the rear in the running direction of the slab is defined as the tail induction heating unit, and a position sensor is provided at a position with a spacing D1 behind the tail induction heating unit in the running direction of the slab, and the position sensor is electrically connected to the controller, D1≥TC×VC, TC is defined as the time required from the start of each first power supply and each second power supply to reaching the preset power, and VC is the running speed of the slab.

[0028] By arranging a position sensor behind the tail induction heating unit, it is convenient to detect the head end and tail end of the slab before they reach the position of the tail induction unit, so as to facilitate early operation.

[0029] Furthermore, each first sensor is mounted on a first frame corresponding to the first sensor, each second sensor is mounted on a second frame corresponding to the second sensor, and each first frame and second frame are independently arranged.

[0030] In the present invention, by providing the first frame and the second frame, each first sensor and each second sensor are provided independently of each other, so that they can be replaced individually.

[0031] Furthermore, a first pulley that slides along the ground rail is installed on the first frame, and a second pulley that slides along the ground rail is installed on the second frame.

[0032] In the present invention, by setting the ground rail, the first pulley and the second pulley, when the equipment needs to be repaired and replaced, the sensor placed on the frame can be pushed and pulled out along the ground rail and the pulley on the frame, so as to realize the rapid disassembly and maintenance of the sensor.

[0033] Furthermore, the tail induction heating unit is a first induction heating unit.

[0034] The present invention also provides an induction heating method using the above-mentioned induction heating system with alternating transverse and longitudinal magnetic fields, the induction heating method comprising:

[0035] The first inductor is energized to generate a transverse magnetic field with a magnetic field direction perpendicular to the surface of the slab, thereby heating the slab located on the slab channel;

[0036] The second inductor is energized to generate a longitudinal magnetic field with a magnetic field direction parallel to the surface of the slab, thereby heating the slab located on the slab channel.

[0037] In the above technical solution, T is defined as the target heating temperature of the slab; the i-th first induction heating unit is powered by the i-th first power supply; the j-th second induction heating unit is powered by the j-th second power supply;

[0038] The induction heating method further comprises:

[0039] At the entrance position of the i-th first induction heating unit, measure the edge temperature TAi of the slab at the entrance position of the i-th first induction heating unit, calculate the i-th first temperature difference △TAi=T-TAi, and set the output power of the i-th first power supply according to the i-th first temperature difference △TAi;

[0040] The surface temperature TBj of the slab at the jth second induction heating unit entrance position is measured at the jth second induction heating unit entrance position, the jth second temperature difference △TBj=T-TBj is calculated, and the output power of the jth second power supply is set according to the jth second temperature difference △TBj.

[0041] In the above technical solution, the induction heating units arranged at the front and rear in the running direction of the slab are defined as the head induction heating unit and the tail induction heating unit respectively. The slab enters from the tail induction heating unit and leaves from the head induction heating unit.

[0042] The induction heating method further comprises:

[0043] If it is detected that the leading end of the slab is located behind the tail induction heating unit in the running direction of the slab and the distance between the leading end of the slab and the tail end of the tail induction heating unit is D1, each first power supply and each second power supply are started, and the output power of each first power supply and each second power supply is gradually increased until the preset power is reached, wherein D1≥TC×VC, TC is defined as the time required from the start of each first power supply and each second power supply to the time when the first preset power is reached, and VC is the running speed of the slab;

[0044] If it is detected that the rear end of the slab is located in front of the head induction heating unit in the running direction of the slab, the output power of each first power supply and each second power supply is gradually reduced until it reaches 0.

[0045] During the research, the applicant found that the rated power of the power supply for the induction heating unit is usually in the megawatt level. If it is directly operated from the start to such a large working power, it will cause great damage to the electronic components and may damage the power supply. By detecting the position of the head end of the slab in the running direction of the slab, each power supply can be turned on in advance before the slab reaches the tail induction unit and the output power of the power supply can be gradually increased to reach the preset power. When the head end of the slab reaches the tail induction unit, the temperature of the slab is detected again, and the output power of the power supply is increased according to the difference between the slab temperature and the target heating temperature, thereby reserving the system response time and avoiding damage to the power supply. In addition, if it is detected that the tail end of the slab is in front of the head induction heating unit, it means that the induction heating system has completed its work, and the output power of each power supply can be gradually reduced, thereby reducing energy consumption.

[0046] The advantages and positive effects of the present invention are:

[0047] 1) Uniform temperature: This patent adopts the zoning heating with alternating vertical and horizontal magnetic fields, and functionally divides each zone into a heating zone and a heat preservation zone. This arrangement not only greatly improves the uniformity of slab temperature and reduces corner cracks, but also improves the uniformity of slab structure, which is beneficial to the improvement of mechanical properties after casting and rolling;

[0048] 2) Simple structure. Although this patent involves two structures, longitudinal magnetic flux inductor and transverse magnetic flux inductor, the two inductors have the same structure, only the arrangement and combination are different, and they can be used as spare parts. Compared with the common process that uses one corner heating system and multiple rolling heating systems, the utilization rate of the equipment is greatly improved;

[0049] 3) Energy saving and consumption reduction. The present invention adopts heating methods with different electrical parameters in different zones, and determines the operating power of the sensor according to temperature detection, which greatly avoids energy waste and saves electric energy;

[0050] 4) Reduce the temperature difference between the head and the tail. This patent uses a position detector and a temperature measuring device to detect the head and tail of the slab, control the switch state of the induction heating power supply and the temperature closed-loop control of gradually changing the power. According to the heating temperature requirements, the heating power is adjusted in real time, which greatly reduces the temperature difference between the head and the tail and improves the yield of finished products.

[0051] Therefore, the present invention uses an induction heating system and heating method with alternating longitudinal and transverse magnetic fields, which can heat the plate quickly and evenly, and has high equipment utilization, energy saving and consumption reduction, and has broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0053] Figure 1 The working principle diagram of the induction heating system with alternating transverse and longitudinal magnetic fields of the present invention;

[0054] Figure 2 It is a schematic diagram of the structure of the sensor of an embodiment of the present invention being arranged on a frame;

[0055] Figure 3 for Figure 2 A partial enlarged schematic diagram of

[0056] Figure 4 This is a schematic diagram of the structure of a slab passing through the first and second sensors according to an embodiment of the present invention;

[0057] Figure 5 This is a schematic diagram of the structure of a slab passing through a third sensor according to an embodiment of the present invention;

[0058] Figure 6 A schematic diagram of the steps of the induction heating method with alternating transverse and longitudinal magnetic fields according to an embodiment of the present invention;

[0059] Figure 7 A schematic diagram comparing the heating effects of the transverse and longitudinal alternating induction heating of the present invention with the transverse magnetic flux induction heating and the longitudinal magnetic flux induction heating of the prior art;

[0060] In the above drawings, 1-slab, 31-first temperature measuring device, 32-second temperature measuring device, 33-third temperature measuring device, 4-position sensor, 50A-first induction heating unit, 50B-second induction heating unit, 51-first inductor, 52-second inductor, 501-first induction coil, 502-second induction coil, 503-third induction coil, 81-first frame, 9-controller, 101-first pulley, 11-ground rail. DETAILED DESCRIPTION

[0061] The following will be combined with the drawings of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0062] like Figure 1-3As shown, this embodiment adopts the following technical scheme: an induction heating system with alternating transverse and longitudinal magnetic fields, which includes: a position sensor 4, a temperature measuring device (a first temperature measuring device 31, a second temperature measuring device 32, and a third temperature measuring device 33), an induction heating device (a first induction heating unit 50A, a second induction heating unit 50B), a cooling system (a first cooling system, a second cooling system), an induction heating power supply (a first power supply, a second power supply), and a controller 9. The position sensor 4 is used to detect the running state of the slab, and to determine whether the head end or the tail end of the slab 1 is about to enter the induction heating system, so as to determine the switch state of the induction heating system. The temperature measuring device is used to detect the temperature of the slab to determine the running power of the induction heating system. The induction heating device is arranged in a multi-zone continuous distribution, which is functionally divided into a heating zone and a heat preservation zone. Multiple induction heaters are arranged in the induction heating unit of each zone. The induction heaters in the same zone (i.e., the first inductor 51 or the second inductor 52) are powered by the same set of induction heating power supplies (i.e., the first power supply or the second power supply) and cooled by the same set of cooling systems (i.e., the first cooling system or the second cooling system). The controller 9 is responsible for the closed-loop control of the whole system. The position sensor and the temperature meter communicate the detection data to the controller 9. After data processing, the controller 9 controls the switch and operating parameters of the induction heating power supply. The controller 9 can adopt a PLC control system. The cooling system can adopt a cooling water system. The cooling system and the induction heating unit are both commonly used devices in the field, and those skilled in the art can understand how to set them.

[0063] The induction heating system includes a first induction heating unit 50A and a second induction heating unit 50B which are alternately arranged in the running direction of the slab. The induction heating unit arranged at the rear in the running direction of the slab is the first induction heating unit 50A. The number of the first induction heating unit 50A and the second induction heating unit 50B are M1 and M2 respectively, M1≥2, M2≥2. In this embodiment, M1=M2=n. n is mainly determined by the temperature rise requirement of the rolled slab and the temperature rise capacity of the induction heating device. In a preferred embodiment, n=2, and it is divided into 4 zones, the first zone (including the first induction heating unit 50A located at the rear in the running direction of the slab), the second zone (including the second induction heating unit 50B located at the rear in the running direction of the slab), the third zone (including the first induction heating unit 50A located at the front in the running direction of the slab), and the fourth zone (including the second induction heating unit 50B located at the front in the running direction of the slab). The first zone and the second zone are heating zones, and the third zone and the fourth zone are insulation zones. The first and third zones are heated by transverse magnetic flux induction, and the second and fourth zones are heated by longitudinal magnetic flux induction. The power of the heating zone can be W≥800Kw. The power of the insulation zone can be W<800Kw.

[0064] The theoretical basis for the continuous arrangement of multi-zone heating in the patent of the present invention is that the efficiency of transverse magnetic flux induction heating is high, and eddy currents are easy to gather at the corners. Continuous use of transverse magnetic flux heating is easy to cause overburning of the corners. Longitudinal magnetic flux induction heating has good temperature uniformity, but low heating efficiency. Before the slab enters the induction heating device, the temperature of the corners is more than 100 degrees lower than the surface temperature due to the heat dissipation of the two surfaces of the slab corners. Therefore, the patent of the present invention adopts a multi-zone heating method. The heating method of alternating transverse and longitudinal magnetic fields is adopted between each zone, such as: Zone 1 adopts a transverse magnetic flux induction heater, which can quickly increase the temperature of the corners first. Zone 2 adopts longitudinal magnetic heating to further heat and evenly heat the slab. Zone 3 is heated by transverse magnetic flux, and Zone 4 is heated by longitudinal magnetic flux. However, after heating in Zones 1-2, the temperature of the slab is basically close to the rolling target temperature. At this time, the main function of Zones 3-4 is to keep warm and micro-control the temperature, and further reach the rolling temperature. Therefore, the heating method that adopts alternating transverse and longitudinal magnetic fields can effectively reduce the temperature deviation between the corners and the surface of the slab, avoiding the problem of overburning of the corners due to continuous transverse magnetic flux heating, or the problem of too low temperature of the corners due to all longitudinal magnetic flux heating.

[0065] Each first induction heating unit 50A includes K1 first inductors 51. Each second induction heating unit 50B includes K2 second inductors 52. 2≤K1≤10, 2≤K2≤10.

[0066] The multi-zone transverse and longitudinal magnetic alternating induction heating system is arranged alternately as follows: from the rear to the front in the direction of the slab running, first set the first induction heating unit 50A, that is, the first inductor 51 using transverse magnetic flux, and then set the second induction heating unit 50B, that is, the second inductor 52 using longitudinal magnetic flux, and so on, so that the first induction heating unit 50A and the second induction heating unit 50B are arranged alternately. From the rear to the front in the direction of the slab running, first use the first inductor 51 of transverse magnetic flux to heat the slab, and its technical advantages are: using the advantages of high heating efficiency of transverse magnetic flux and easy gathering of magnetic lines of force at corners, first greatly increase the corner temperature, and compensate for the heat dissipation of the corners before the slab enters the induction heating device. Then use the second inductor 52 of longitudinal magnetic flux to evenly heat the entire ingot, and then use the heat conduction of the slab itself to further even the temperature. Similarly, the subsequent heating zones also use the heating method of alternating transverse and longitudinal magnetic induction to achieve the purpose of heating and equalizing the slab.

[0067] The induction heating units are evenly arranged on the rolling line. In a preferred embodiment, each zone is composed of: a set of induction heating units (the first induction heating unit 50A or the second induction heating unit 50B), a set of cooling systems (i.e., the first cooling system or the second cooling system) and a set of induction heating power supplies (i.e., the first power supply or the second power supply). The controller 9 controls the induction heating power supplies, the temperature measuring device, and the position sensor 4.

[0068] The inlet end of each first induction heating unit 50A is provided with a first temperature measuring device 31 for measuring the edge temperature of the slab, the inlet end of each second induction heating unit 50B is provided with a second temperature measuring device 32 for measuring the surface temperature of the slab, and the outlet end of the slab channel is provided with a third temperature measuring device 33 for measuring the surface temperature of the slab. The edge temperature of the slab is the wall temperature of at least one side of the slab 1 in the running direction of the slab, and the surface temperature of the slab is at least one of the upper surface temperature of the slab or the lower surface temperature of the slab. The first temperature measuring device can measure the edge temperature of the slab at the inlet end of the first induction heating unit 50A. The edge temperature of the slab can be the wall temperature of one side of the slab 1 in the running direction of the slab, or the wall temperature of the other side of the slab 1, or the average of the wall temperatures on both sides. The second temperature measuring device 32 can measure the surface temperature of the slab at the inlet end of the second induction heating unit 50B. The slab surface temperature may be the upper surface temperature of the slab 1, the lower surface temperature of the slab 1, or the average of the upper and lower surface temperatures. The third temperature measuring device 33 measures the slab surface temperature of the slab 1 at the outlet end of the slab channel, that is, the third temperature measuring device 33 is arranged to measure the slab surface temperature at the outlet end of the induction heating unit (for example, the second induction heating unit 50B) located at the front in the slab running direction.

[0069] Each first power supply, each second power supply, each first cooling system, each second cooling system, each first temperature measuring device 31 , each second temperature measuring device 32 , and each third temperature measuring device 33 are electrically connected to the controller 9 .

[0070] The measurement results of each temperature measuring device are communicated to the controller 9.

[0071] In a preferred embodiment, the induction heating system further comprises M1 first cooling systems, M2 second cooling systems, M1 first power supplies, and M2 second power supplies;

[0072] Each first cooling system, each second cooling system, each first power supply, and each second power supply are independently arranged;

[0073] The first induction coil 501 and the second induction coil 502 in the i-th first induction heating unit 50A are both powered by the i-th first power supply and are both cooled by the i-th first cooling system;

[0074] The third induction coil 503 in the j-th second induction heating unit 50B is powered by the j-th second power supply and cooled by the j-th second cooling system;

[0075] i=1,2,…,M1, j=1,2,…,M2;

[0076] In a preferred embodiment, the first induction heating unit 50A arranged at the rear in the running direction of the slab is defined as the tail induction heating unit, and a position sensor 4 is provided at a position with a spacing D1 behind the tail induction heating unit in the running direction of the slab, and the position sensor 4 is electrically connected to the controller 9. D1≥TC×VC, TC is defined as the time required from the start of each first power supply and each second power supply to reach the preset power (or the induction heating power supply start-up response time), and VC is the slab running speed. The time required from the start of each first power supply and each second power supply to reach the preset power is the time required for each first power supply and each second power supply to reach its preset power from startup. Figure 1 , Figure 2 As shown, the distance between the position sensor 4 and the end of the first zone is D1. The position sensor is mainly used to detect whether the head and tail ends of the plate have arrived (i.e., detect whether the head and tail ends are at a distance of D1 from the end of the first zone). The controller 9 controls the output power of the induction power supply to prevent the high power heating power from causing overburning of the edge when the head and tail of the slab pass through the induction heating device of zone 1. In a preferred embodiment, VC is not greater than 1m / s, TC is not less than 10s, and D1 is not less than 12m.

[0077] In the present invention, the position sensor 4 can be used to detect whether the tail end of the slab is at a distance D1 from the end of the first zone. Based on the known total length of the induction heating system, the length of D1, and the speed of the slab, it can be determined when the tail end of the slab is located in front of the head induction heating unit.

[0078] In the present invention, the induction heaters in the same zone are powered by the same induction heating power supply, and the heating power can be controlled independently.

[0079] In a preferred embodiment, each first sensor 51 is respectively installed on a first frame 81 corresponding to the first sensor 51, and each second sensor 52 is respectively installed on a second frame corresponding to the second sensor 52, and each first frame 81 and second frame are independently arranged.

[0080] A first pulley 101 that slides along the ground rail 11 is installed on the first frame 81 , and a second pulley that slides along the ground rail 11 is installed on the second frame.

[0081] In the above arrangement, each inductor is installed on a steel rolling frame. The slab is driven by a variable frequency motor and the non-magnetic roller continuously moves the slab 1 through the induction heater. In order to meet the needs of fast-paced production, when the equipment needs to be repaired and replaced, the inductor placed on the frame can be pushed and pulled out along the ground rail and the pulley on the frame with the frame, so as to realize the rapid disassembly and maintenance of the inductor.

[0082] There are two types of induction heaters in the induction heating system of this patent.

[0083] like Figure 4 As shown, the first inductor 51 is a transverse flux induction heater. The first inductor 51 includes a first induction coil 501 and a second induction coil 502 which are arranged in pairs and are respectively located above and below the slab channel. The coil planes of the first induction coil 501 and the coil planes of the second induction coil 502 are arranged opposite to each other. When current is passed through the first induction coil 501 and the second induction coil 502, a transverse magnetic field with a magnetic field direction perpendicular to the surface of the slab is generated, thereby heating the slab 1 located on the slab channel. In this embodiment, the first induction coil 501 and the second induction coil 502 are both U-shaped coils, and are installed opposite to each other in the horizontal direction along the upper and lower surfaces of the slab. The first induction coil 501 and the second induction coil 502 can also be annular coils. The magnetic field lines of force generated by the first induction coil 501 and the second induction coil 502 are perpendicular to the cross section of the slab.

[0084] like Figure 5 As shown, the second inductor 52 is a longitudinal magnetic flux induction heater. The second inductor 52 includes a third induction coil 503 with a middle opening, and the slab channel passes through the middle opening of the third induction coil 503. When the third induction coil 503 is energized with current, a longitudinal magnetic field is generated with a magnetic field direction parallel to the slab surface, thereby heating the slab 1 located on the slab channel. In this embodiment, the third induction coil 503 is a U-shaped coil and is installed upright in the height direction of the slab. The third induction coil 503 can also be a ring coil. The magnetic field lines of force generated by the third induction coil 503 are parallel to the slab surface.

[0085] Since each induction coil adopts a modular U-shaped structure design, the equipment manufacturing process and cost are greatly reduced. Each induction coil is wound with a high-conductivity water-cooled hollow copper tube. Each turn of the copper tube is wrapped with high-temperature and wear-resistant insulating materials, and the outside is cast with high-strength refractory materials to form a whole.

[0086] like Figure 6As shown, when the state detected by the position sensor 4 is the head end of the slab, that is, the process from no slab to slab, the induction heating system is turned on at a low power in advance; when the position sensor detects the tail end of the slab, that is, the process from the continuous state of slab to the state of no slab, the induction heating system will gradually reduce the power of the induction heating power supply until it is turned off. Setting a process for delaying the opening and closing of the induction heating power supply can, on the one hand, avoid damage to components caused by the instantaneous high-power switching of the induction heating power supply, and on the other hand, provide the prerequisite for the induction heating power supply to run to the optimal power before the head and tail ends of the slab pass through. The operating power of the induction heating device in each specific zone is controlled by the temperature closed loop of the temperature meter, and its control method can be adopted as follows:

[0087] (1) The edge temperature T1 of the slab at the inlet end of the first induction heating unit 50A (Zone 1) located at the rear in the running direction of the slab is detected, and the detected temperature T1 is compared with the target temperature T. The temperature rise requirement is obtained by △T=T-T1, and the heating power of the induction heating device in Zone 1 is determined. The controller 9 controls the induction heating device in Zone 1 to operate to the required heating power.

[0088] (2) Detect the slab surface temperature T2 at the inlet end of the second induction heating unit 50B (zone 2) located at the rear in the slab running direction, compare T2 with the rolling target temperature T, and obtain ΔT=T-T1, and determine the operating power of the induction heating device in zone 2;

[0089] (3) The slab edge temperature T3 at the inlet end of the first induction heating unit 50A (zone 3) located in the front in the slab running direction is detected, T3 is compared with the rolling target temperature T, and △T=T-T3 is obtained, and the operating power of the induction heating device in zone 3 is determined;

[0090] (4) The slab surface temperature T4 at the entrance end of the second induction heating unit 50B (4th zone) located in the front in the slab running direction is detected, T4 is compared with the rolling target temperature T, and △T=T-T4 is obtained to determine the operating power of the induction heating device in the 4th zone.

[0091] When the position sensor D1 detects the slab head, the power runs to: 0~100Kw. When the temperature sensor T1 detects the head temperature, the power increases from 100Kw to the rated power P.

[0092] (1) When the position sensor D1 detects the tail of the slab, the power is reduced by 100Kw; when the temperature sensor T1 detects the tail temperature, the power runs to the rated power P1;

[0093] (2) The reason for starting up in advance and gradually reducing the power is to reserve a system response time. This is mainly because the rated power of induction heating is usually in the megawatt level. Directly running at such a high working power will cause great damage to electronic components.

[0094] The present invention provides an induction heating method with alternating transverse and longitudinal magnetic fields, wherein a channel through which a slab 1 passes is defined as a slab channel, and first induction heating units 50A and second induction heating units 50B are alternately arranged in a running direction of the slab, and the numbers of the first induction heating units 50A and the second induction heating units 50B are M1 and M2, respectively, M1≥2, M2≥2;

[0095] Each first induction heating unit 50A includes K1 first inductors 51;

[0096] Each second induction heating unit 50B includes K2 second inductors 52;

[0097] The first inductor 51 includes a first induction coil 501 and a second induction coil 502 respectively located above and below the slab channel, and the first induction coil 501 and the second induction coil 502 are arranged in pairs;

[0098] The second inductor 52 includes a third induction coil 503 having a middle opening, and the slab passage passes through the middle opening of the third induction coil 503;

[0099] The first induction coil 501 and the second induction coil 502 are in a ring shape or a U-shaped shape, and the third induction coil 503 is in a ring shape or a U-shaped shape;

[0100] The induction heating method includes: current is passed through the first induction coil 501 and the second induction coil 502 to generate a transverse magnetic field with a magnetic field direction perpendicular to the slab surface, thereby heating the slab 1 located on the slab channel; current is passed through the third induction coil 503 to generate a longitudinal magnetic field with a magnetic field direction parallel to the slab surface, thereby heating the slab 1 located on the slab channel.

[0101] In a preferred embodiment of the present invention, M1=M2 and both M1 and M2 are even numbers, the preset power of the first power supply corresponding to the M1 / 2 first induction heating units located in the front in the running direction of the slab and the first power supply corresponding to the M2 / 2 second induction heating units located in the front in the running direction of the slab are both W1, the preset power of the first power supply corresponding to the M1 / 2 first induction heating units located in the rear in the running direction of the slab and the first power supply corresponding to the M2 / 2 second induction heating units located in the rear in the running direction of the slab are both W2, and W1<W2. For example, in this embodiment, M1 and M2 are both 2.

[0102] Define T as the target heating temperature of the slab 1; the first induction coil 501 and the second induction coil 502 in the i-th first induction heating unit 50A are both powered by the i-th first power supply; the third induction coil 503 in the j-th second induction heating unit 50B is powered by the j-th second power supply;

[0103] The induction heating method further comprises:

[0104] The edge temperature TAi of the slab at the entrance position of the i-th first induction heating unit 50A is measured, and the controller 9 calculates the i-th first temperature difference △TAi=T-TAi, and the controller 9 sets the output power of the i-th first power supply according to the i-th first temperature difference △TAi;

[0105] The surface temperature TBj of the slab at the entrance position of the jth second induction heating unit 50B is measured at the entrance position of the jth second induction heating unit 50B, and the controller 9 calculates the jth second temperature difference △TBj=T-TBj. The controller 9 sets the output power of the jth second power supply according to the jth second temperature difference △TBj.

[0106] The induction heating unit disposed at the front in the running direction of the slab is defined as a head induction heating unit; the induction heating method further comprises:

[0107] If it is detected that the leading end of the slab 1 is located behind the tail induction heating unit in the running direction of the slab and the distance between the leading end of the slab 1 and the tail end of the tail induction heating unit is D1, the controller 9 starts each first power supply and each second power supply, and gradually increases the output power of each first power supply and each second power supply until it reaches a preset power, wherein D1≥TC×VC, TC is defined as the time required from the start of each first power supply and each second power supply to the time when the preset power is reached, and VC is the running speed of the slab;

[0108] If it is detected that the rear end of the slab 1 is located in front of the head induction heating unit in the running direction of the slab, the controller 9 gradually reduces the output power of each first power supply and each second power supply until it reaches 0.

[0109] In a preferred embodiment, the output power increase rate and decrease rate may be 100 KW / s.

[0110] like Figure 7The figure shows a schematic diagram comparing the heating effects of the induction heating system of the patented alternating transverse and longitudinal magnetic fields with the transverse magnetic flux induction heating and longitudinal magnetic flux induction heating of the prior art. The slab specifications are: 60-80mm thick and 1600mm wide stainless steel plates. The slab runs at a speed of 1.0m / s under the drive of the non-magnetic roller, and the temperature of the plate before entering the inductor is 750-900 degrees. The design adopts a 4-zone arrangement (i.e., two first induction heating units 50A and two second induction heating units 50B are arranged alternately), with 4 induction heaters in each zone, and a total of 16 induction heaters (i.e., including 8 first inductors 51 and 8 second inductors 52).

[0111] like Figure 7 As shown in , for the existing induction heating system using longitudinal magnetic flux, since the longitudinal magnetic flux heating is relatively uniform, the temperature of the corners is more than 100 degrees lower than the surface temperature before entering the induction heating device. After the slab is heated, the edge temperature is still more than 100 degrees lower than the surface temperature, so it is difficult to achieve a uniform rolling temperature; for the existing induction heating system using transverse magnetic flux, since the edge temperature is continuously heated, it is easy to cause overburning, and the edge softens during rolling, causing the slab to easily deviate. The present invention adopts the method of alternating transverse and longitudinal magnetic fields to better solve the above problem of uneven temperature, and the heating efficiency and heating effect are relatively good.

[0112] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0113] The embodiments of the present invention are described in detail above, but the contents are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of this patent. After reading the present invention, modifications of various equivalent forms of the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application. In the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

Claims

1. An induction heating system with alternating transverse and longitudinal magnetic fields, wherein a channel through which a slab (1) passes is defined as a slab channel, and characterized in that: The induction heating system comprises a first induction heating unit (50A) and a second induction heating unit (50B) which are alternately arranged in the running direction of the slab, the induction heating unit arranged at the rear in the running direction of the slab is the first induction heating unit (50A), the number of the first induction heating unit (50A) and the number of the second induction heating unit (50B) are M1 and M2 respectively, M1≥2, M2≥2; Each first induction heating unit (50A) comprises K1 first inductors (51) for generating a transverse magnetic field with a magnetic field direction perpendicular to the surface of the slab, thereby heating the slab (1) located on the slab channel; Each second induction heating unit (50B) comprises K2 second inductors (52) for generating a longitudinal magnetic field with a magnetic field direction parallel to the surface of the slab, thereby heating the slab (1) located on the slab channel; The induction heating system further comprises a controller (9), M1 first cooling systems, M2 second cooling systems, M1 first power supplies, and M2 second power supplies; Each first cooling system, each second cooling system, each first power supply, and each second power supply are independently arranged; The i-th first induction heating unit (50A) is powered by the i-th first power supply and cooled by the i-th first cooling system; The jth second induction heating unit (50B) is powered by the jth second power supply and cooled by the jth second cooling system; i=1,2,…,M1, j=1,2,…,M2; M1=M2, K1=K2; A first temperature measuring device (31) for measuring the edge temperature of a slab is provided at the inlet position of each first induction heating unit (50A), a second temperature measuring device (32) for measuring the surface temperature of a slab is provided at the inlet position of each second induction heating unit (50B), and a third temperature measuring device (33) for measuring the surface temperature of a slab is provided at the outlet position of the slab channel, the edge temperature of the slab being the temperature of at least one side of the wall of the slab (1) in the running direction of the slab, and the surface temperature of the slab being at least one of the upper surface temperature of the slab or the lower surface temperature of the slab; Each first power supply, each second power supply, each first cooling system, each second cooling system, each first temperature measuring device (31), each second temperature measuring device (32), and each third temperature measuring device (33) are electrically connected to the controller (9); The first induction heating unit (50A) arranged at the rear in the running direction of the slab is defined as a tail induction heating unit. A position sensor (4) is provided at a position with a spacing D1 behind the tail induction heating unit in the running direction of the slab. The position sensor (4) is electrically connected to a controller (9). D1≥TC×VC. TC is defined as the time required from the start of each first power supply and each second power supply to reaching a preset power. VC is the running speed of the slab.

2. The induction heating system according to claim 1, characterized in that: Each first inductor (51) comprises a first induction coil (501) and a second induction coil (502) which are arranged in pair and are respectively located above and below the slab channel, wherein the coil planes of the first induction coil (501) and the coil planes of the second induction coil (502) are arranged relative to each other, and when current is passed through the first induction coil (501) and the second induction coil (502), a transverse magnetic field is generated with a magnetic field direction perpendicular to the slab surface, thereby heating the slab (1) located on the slab channel.

3. The induction heating system according to claim 2, characterized in that: The first induction coil (501) and the second induction coil (502) are ring-shaped.

4. The induction heating system according to claim 2, characterized in that: The first induction coil (501) and the second induction coil (502) are in the shape of a Chinese umbilical cord.

5. The induction heating system according to claim 2, characterized in that: The coil planes of the first induction coil (501) and the second induction coil (502) are both parallel to the cross section of the slab (1).

6. The induction heating system according to claim 1, characterized in that: Each second inductor (52) comprises a third induction coil (503) having a middle opening, and the slab channel passes through the middle opening of the third induction coil (503). When current is passed through the third induction coil (503), a longitudinal magnetic field is generated with a magnetic field direction parallel to the slab surface, thereby heating the slab (1) located on the slab channel.

7. The induction heating system according to claim 6, characterized in that: The third induction coil (503) is in a ring shape.

8. The induction heating system according to claim 6, characterized in that: The third induction coil (503) is in the shape of a Chinese umbilical cord.

9. The induction heating system according to claim 6, characterized in that: The coil plane of the third induction coil (503) is perpendicular to the running direction of the slab.

10. The induction heating system according to claim 1, characterized in that: M1=M2=2, K1=K2=4.

11. The induction heating system according to any one of claims 1 to 9, characterized in that: Each first sensor (51) is mounted on a first frame (81) corresponding to the first sensor (51), and each second sensor (52) is mounted on a second frame corresponding to the second sensor (52). Each first frame (81) and second frame are independently arranged.

12. The induction heating system according to claim 11, characterized in that: A first pulley (101) is mounted on the first frame (81) and slides along the ground rail (11), and a second pulley is mounted on the second frame and slides along the ground rail (11).

13. An induction heating method using alternating transverse and longitudinal magnetic fields of an induction heating system, wherein a channel through which a slab (1) passes is defined as a slab channel, and characterized in that: The induction heating system comprises a first induction heating unit (50A) and a second induction heating unit (50B) which are alternately arranged in the running direction of the slab, the induction heating unit arranged at the rear in the running direction of the slab is the first induction heating unit (50A), the number of the first induction heating unit (50A) and the number of the second induction heating unit (50B) are M1 and M2 respectively, M1≥2, M2≥2; Each first induction heating unit (50A) comprises K1 first inductors (51) for generating a transverse magnetic field with a magnetic field direction perpendicular to the surface of the slab, thereby heating the slab (1) located on the slab channel; Each second induction heating unit (50B) comprises K2 second inductors (52) for generating a longitudinal magnetic field with a magnetic field direction parallel to the surface of the slab, thereby heating the slab (1) located on the slab channel; The induction heating method comprises: The first inductor (51) is energized to generate a transverse magnetic field with a magnetic field direction perpendicular to the surface of the slab, thereby heating the slab (1) located on the slab channel; The second inductor (52) is energized to generate a longitudinal magnetic field with a magnetic field direction parallel to the surface of the slab, thereby heating the slab (1) located on the slab channel; T is defined as the target heating temperature of the slab (1); the i-th first induction heating unit (50A) is powered by the i-th first power supply; the j-th second induction heating unit (50B) is powered by the j-th second power supply; The induction heating method further comprises: measuring the edge temperature TAi of the slab at the entrance position of the i-th first induction heating unit (50A), calculating the i-th first temperature difference △TAi=T-TAi, and setting the output power of the i-th first power supply according to the i-th first temperature difference △TAi; The surface temperature TBj of the slab at the entrance position of the jth second induction heating unit (50B) is measured, the jth second temperature difference △TBj=T-TBj is calculated, and the output power of the jth second power supply is set according to the jth second temperature difference △TBj.

14. The induction heating method according to claim 13, characterized in that: The induction heating units arranged at the front and rear in the running direction of the slab are defined as a head induction heating unit and a tail induction heating unit respectively; the induction heating method further comprises: If it is detected that the front end of the slab (1) is located behind the rear induction heating unit in the running direction of the slab and the distance between the front end of the slab (1) and the rear end of the rear induction heating unit is D1, each first power supply and each second power supply are started, and the output power of each first power supply and each second power supply is gradually increased until a preset power is reached, wherein D1≥TC×VC, TC is defined as the time required from the start of each first power supply and each second power supply to the reaching of the preset power, and VC is the running speed of the slab; If it is detected that the rear end of the slab (1) is located in front of the head induction heating unit in the running direction of the slab, the output power of each first power supply and each second power supply is gradually reduced until it reaches 0.

15. The induction heating method according to claim 13, characterized in that: Each first inductor (51) comprises a first induction coil (501) and a second induction coil (502) which are arranged in pair and are respectively located above and below the slab channel, wherein the coil planes of the first induction coil (501) and the coil planes of the second induction coil (502) are arranged relative to each other, and when current is passed through the first induction coil (501) and the second induction coil (502), a transverse magnetic field is generated with a magnetic field direction perpendicular to the slab surface, thereby heating the slab (1) located on the slab channel.

16. The induction heating method according to claim 13, characterized in that: Each second inductor (52) comprises a third induction coil (503) having a middle opening, and the slab channel passes through the middle opening of the third induction coil (503). When current is passed through the third induction coil (503), a longitudinal magnetic field is generated with a magnetic field direction parallel to the slab surface, thereby heating the slab (1) located on the slab channel.

17. The induction heating method according to claim 13, characterized in that: M1=M2, K1=K2.

18. The induction heating method according to claim 13, characterized in that: It also includes a controller (9), M1 first cooling systems, M2 second cooling systems, M1 first power supplies, and M2 second power supplies; Each first cooling system, each second cooling system, each first power supply, and each second power supply are independently arranged; The i-th first induction heating unit (50A) is powered by the i-th first power supply and cooled by the i-th first cooling system; The jth second induction heating unit (50B) is powered by the jth second power supply and cooled by the jth second cooling system; i=1,2,…,M1, j=1,2,…,M2; A first temperature measuring device (31) for measuring the edge temperature of a slab is provided at the inlet position of each first induction heating unit (50A), a second temperature measuring device (32) for measuring the surface temperature of a slab is provided at the inlet position of each second induction heating unit (50B), and a third temperature measuring device (33) for measuring the surface temperature of a slab is provided at the outlet position of the slab channel, the edge temperature of the slab being the temperature of at least one side of the wall of the slab (1) in the running direction of the slab, and the surface temperature of the slab being at least one of the upper surface temperature of the slab or the lower surface temperature of the slab; Each first power supply, each second power supply, each first cooling system, each second cooling system, each first temperature measuring device (31), each second temperature measuring device (32), and each third temperature measuring device (33) are electrically connected to the controller (9).

19. The induction heating method according to any one of claims 13 to 18, characterized in that: Each first sensor (51) is mounted on a first frame (81) corresponding to the first sensor (51), and each second sensor (52) is mounted on a second frame corresponding to the second sensor (52). Each first frame (81) and second frame are independently arranged.

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