Induction heating apparatus

Abstract

To provide an induction heating apparatus capable of preventing collision of even a bent steel plate and suppressing reduction in yield of the steel plate.SOLUTION: This induction heating apparatus comprises: a C-type edge heater that heats the edge of a steel plate; a camera provided on the upstream side of the C-type edge heater; an image processing device that measures the size of bending of each of the tip and the tail end of the steep plate on the basis of image data of the steel plate generated by the camera; a drive device that drives a motor for adjusting a gap amount between upper and lower inductors of the C-type edge heater; a control device that feedback-controls the gap amount on the basis of the bending; and a power conversion device that supplies power based on a heating power amount fed to the steel plate to the C-type edge heater. The control device generates a speed command so as to adjust the gap amount in accordance with the bending size, and corrects the heating power amount fed to the steel plate in accordance with the gap amount.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to an induction heating device for heating a steel plate in a steel rolling plant.

Background Art

[0002] In a steel line, a product with a desired plate thickness is obtained by rolling a steel plate heated to a predetermined temperature with a rolling mill. In order to equalize the temperature drop at the edge portions on both sides of the steel material and reduce the load on the equipment in subsequent processes such as the rolling mill, an induction heating device having a C-shaped edge heater for heating the edge portions on both sides of the steel plate may be installed (see, for example, Patent Document 1, etc.).

[0003] In hot rolling of a steel plate, for example, the following processes exist from a heating furnace to a crop shear that cuts the crops at the tip and tail ends of the steel plate. That is, the slab that has exited the heating furnace is reduced in width by pressing the side surfaces with a sizing press. The slab with the side surfaces reduced is rolled by a rough rolling mill. The rolled steel plate passes through a heating process by an induction heating device having a C-shaped edge heater, and the crops at the tip and tail ends are cut by a crop shear.

[0004] In the above process, the side surface of the high-temperature steel plate extracted from the heating furnace is pressed by a sizing press to narrow the plate width, and the steel plate rolled by the rough rolling mill to reduce the plate thickness is heated by a C-shaped edge heater. In the processes of the sizing press and the rough rolling mill, the tip and tail ends of the steel plate may warp in the longitudinal direction. When the warped steel plate enters the C-shaped edge heater, there is a risk that the warped portion of the steel plate may come into contact with or collide with the upper inductor.

[0005] Therefore, a warp detector is installed upstream of the C-shaped edge heater, and when a warped steel plate contacts the warp detector, an alarm is generated to stop the equipment, thereby preventing the warped steel plate from colliding with the upper inductor.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 11-144853 [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] However, even though the above method can protect the equipment, since it stops the equipment itself, there may be a problem of reducing the operation rate of the plant. Also, in such a protection system, since the magnitude of the warp of the steel plate is not measured, the gap between the upper inductor and the lower inductor is set to the maximum gap amount so that the steel plate does not collide with the upper inductor. Therefore, even though the steel plate has passed through the induction heating device, the heating of the steel plate may not be sufficient, and the quality of the steel plate may deteriorate. Also, the wear of the roll rolling in the finishing mill may become uneven, the length of the crop when cutting by the crop shear may increase, and the yield may decrease.

[0008] An embodiment of the present invention aims to provide an induction heating device that can prevent the collision of a steel plate and suppress the decrease in the yield rate of the steel plate even for a warped steel plate. [Means for Solving the Problems]

[0009] The induction heating device according to the present invention includes a C-shaped edge heater 1 including an upper inductor and a lower inductor provided via a gap so as to heat an edge along the conveyance direction of a steel sheet, a camera provided upstream of the C-shaped edge heater, imaging a steel sheet entering the C-shaped edge heater to generate and output image data, an image processing device that performs image processing on the image data to measure and output the magnitude of warpage of each of the tip and tail ends of the steel sheet, a drive device that drives a motor to move the upper inductor up and down to adjust a gap amount representing the size of the gap between the upper inductor and the lower inductor, a control device that calculates a set value of the gap amount based on the data of the magnitude of warpage and generates a speed command so that a measured value of the measured gap amount follows the set value and outputs it to the drive device, and a power conversion device that supplies power to the upper inductor and the lower inductor according to the amount of heating power input to the steel sheet. The control device calculates the amount of heating power based on the measured value and a pre-set temperature rise value for the steel sheet. The control device makes the set value constant with respect to the warpage magnitude of the tip by tracking the position of the tip, and makes the set value constant with respect to the warpage magnitude of the tail end by tracking the position of the tail end, during the period from when the tip of the steel sheet enters the C-shaped edge heater until it exits, and during the period from when the tail end of the steel sheet enters the C-shaped edge heater until it exits.

Advantages of the Invention

[0010] According to an embodiment of the present invention, it is possible to provide an induction heating device that can prevent a steel sheet from colliding and suppress a decrease in the yield rate of the steel sheet even for a warped steel sheet.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments will be described with reference to the drawings. Note that the drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the sizes between parts, etc. are not necessarily the same as those in reality. Also, even when representing the same part, there are cases where the dimensions and ratios are represented differently in the drawings. In the present specification and each drawing, the same reference numerals are given to the same elements as those described above with respect to the previously shown drawings, and detailed descriptions are omitted as appropriate.

[0013] FIG. 1 is a schematic block diagram illustrating an induction heating apparatus according to an embodiment. As shown in FIG. 1, an induction heating apparatus 100 according to an embodiment includes a C-shaped edge heater 1, a camera 6, an image processing device 7, a control device 8, a drive device 9, and a frequency conversion device 10. In FIG. 1, among the induction heating apparatus 100, the C-shaped edge heater 1 within the broken line is schematically shown in order to represent the physical structure and configuration of the C-shaped edge heater 1.

[0014] The C-shaped edge heater 1 includes an upper inductor 2, a lower inductor 14, and an AC motor 11. The upper inductor 2 and the lower inductor 14 have a common iron core 3 in the shape of the letter "C". In the upper inductor 2, a heating coil 4 is wound around the upper iron core 3, and in the lower inductor 14, a heating coil 4 is wound around the lower iron core 3. In the example of FIG. 1, two sets of a combination of the upper inductor 2 and the lower inductor 14 are provided along the conveying direction of the steel plate 5.

[0015] In the C-shaped edge heater 1, the upper inductor 2 is arranged vertically above the lower inductor 14 with a gap on the pass line P1. The size of the gap is represented by a gap amount G1 which is the separation distance between the upper inductor 2 and the lower inductor 14. The steel plate 5 is conveyed along the pass line P1. The pass line P1 is formed by the conveying rollers 12 arranged in the conveying direction. The steel plate 5 conveyed along the pass line P1 passes through the gap of the size of the gap amount G1. As will be described later, the upper inductor 2 can be moved up and down by an AC motor 11 controlled by a drive device 9. By moving the upper inductor 2 up and down, the size of the gap amount G1 is adjusted. The size of the gap amount G1 is determined based on the degree of warping of the steel plate 5.

[0016] Wheels 13 are provided at the lower part of the C-shaped edge heater 1. The wheels 13 are arranged to move the C-shaped edge heater 1 in a direction orthogonal to the conveying direction of the steel plate 5.

[0017] The camera 6 is arranged upstream of the C-shaped edge heater 1. The camera 6 is provided to image the steel plate 5 conveyed on the pass line P1. For example, the camera 6 is arranged above the surface of the steel plate 5 and images the steel plate 5 across the width direction of the steel plate 5. The camera 6 generates image data of the imaged steel plate 5 and outputs it to the image processing device 7.

[0018] The image processing device 7 is connected to the camera 6. The image processing device 7 processes the image data of the steel plate 5 output by the camera 6 and measures the warping of the tip and tail ends of the steel plate 5. The image processing device 7 outputs the respective data of the measured warping of the tip and tail ends of the steel plate 5 to the control device 8.

[0019] The warpage of the front end and the rear end of the steel plate 5 is defined as follows, for example. The warpage of the front end is defined by the warpage height W1 and the warpage length L1. The warpage of the rear end is defined by the warpage height W2 and the warpage length L2. For example, the warpage heights W1 and W2 are the maximum heights in the width direction of the steel plate 5 with respect to the pass line P1. The warpage lengths L1 and L2 are defined as the lengths in the direction of the pass line P1. That is, the warpage length L1 of the front end is the length in the direction of the pass line P1 from the position of the front end of the steel plate 5 to the position where the warpage height becomes less than or equal to a predetermined value. The warpage length L2 of the rear end is the length in the direction of the pass line P1 from the position where the warpage height becomes less than or equal to a predetermined value to the position of the rear end.

[0020] Hereinafter, the end portions in the conveying direction of the steel plate 5 are referred to as the "front end" and the "rear end". The portion of the steel plate 5 within the range of the length L1 including the "front end" is referred to as the "front end portion", and the portion of the steel plate 5 within the range of the length L2 including the "rear end" is referred to as the "rear end portion".

[0021] The control device 8 is connected to the image processing device 7, the drive device 9, and the frequency conversion device 10. The control device 8 has a function of adjusting the magnitude of the gap amount G1 and a function of calculating the heating power amount for heating the steel plate 5 in the case of the adjusted gap amount G1.

[0022] The function of the control device 8 to adjust the magnitude of the gap amount G1 is adjusted using feedback control based on the set value of the gap amount set by measuring the warpage of the steel plate 5. More specifically, the control device 8 sequentially calculates the set value of the gap amount based on the warpage data of the front end portion and the rear end portion of the steel plate 5 output by the image processing device 7. The C-type edge heater 1 is provided with a measuring means for the gap amount G1. The measuring means for the gap amount G1 measures data related to the gap amount G1 and outputs the measured data to the control device 8. The control device 8 generates a speed command so that the measured gap amount G1 follows the set value of the gap amount and outputs it to the drive device 9.

[0023] The function of calculating the heating power of the control device 8 calculates a correction value for the heating power based on the measured gap amount G1 and calculates the corrected heating power. More specifically, the control device 8 calculates the heating power of the steel plate 5 based on a preset temperature rise value of the steel plate 5. The control device 8 corrects the calculated heating power based on the measured gap amount G1 data. The control device 8 adds the correction value of the heating power to the heating power to calculate the corrected heating power, and outputs the calculated heating power as a power command to the frequency conversion device 10.

[0024] The configuration example of the control device 8 will be described in more detail. FIG. 2 and FIG. 3 are schematic block diagrams illustrating a part of the control device constituting the induction heating device according to the embodiment. FIG. 2 shows the configuration of the control device 8 for feedback control of the gap amount G1 according to the warpage data of the steel plate 5. FIG. 3 shows a configuration for generating a correction value so as to obtain an appropriate heating power and calculating the corrected heating power in the case of the gap amount G1 controlled by the configuration of FIG. 2.

[0025] As shown in FIG. 2, the control device 8 has a controller 20. The controller 20 is, for example, a PI controller. In this example, the control device 8 has a position calculation module (denoted as Absolute Encorder Module in FIG. 2) 8b as a means for measuring the gap amount G1. The position calculation module 8b inputs the rotation angle data of the AC motor 11 from the rotation angle detector (denoted as ABS in FIG. 2) 1a and calculates the moving distance of the upper inductor 2. The control device 8 calculates the gap amount G1 using the moving distance of the upper inductor 2. In the control device 8, the calculated gap amount G1 is supplied to the controller 20.

[0026] The control device 8 is preset with a reference gap amount B. The reference gap amount B is a set value of the gap amount when the steel plate 5 has no warp, and is set by a host computer according to attribute values such as the thickness of the steel plate, for example. The control device 8 is sequentially input with a warp amount A, which is data on the warp of the steel plate 5, from the image processing device 7. The control device 8 adds the warp amount A to the reference gap amount B and supplies it to the controller 20.

[0027] The controller 20 generates a speed command so that the calculated gap amount G1 follows the set value (B + A) of the gap amount obtained by adding the warp amount A to the reference gap amount B. The control device 8 sequentially outputs the generated speed command to the drive device 9.

[0028] The control device 8 can be provided with appropriate components according to the characteristics of the AC motor 11, the accuracy of measurement means such as control amounts and physical quantities, and the response speed of the control system. In the specific example of FIG. 2, when the added value of the warp amount A and the reference gap amount B becomes a predetermined value or more, a limiter 8a for providing a limit value, limiters 21 and 24 for speed limits, and an acceleration / deceleration rate setter 22 for setting the acceleration / deceleration of the AC motor 11, a constant setter 23 for PI control, etc. are provided in the controller 20.

[0029] As shown in FIG. 3, the control device 8 has a heating power amount calculation unit 41. The heating power amount calculation unit 41 is supplied with, for example, a temperature rise value preset by the host computer 30 in advance. In the host computer 30, the temperature rise value is set for each steel plate 5, for example, according to the thickness and material of the steel plate 5.

[0030] The heating power calculation unit 41 calculates the heating power based on the temperature rise value. In this example, data on the conveyance speed of the steel sheet 5 (denoted as the material conveyance speed in FIG. 3) is supplied to the heating power calculation unit 41, and the heating power is corrected according to the conveyance speed of the steel sheet 5. The conveyance speed of the steel sheet 5 is calculated, for example, by detecting the rotational speed of the conveyance roll that conveys the steel sheet 5 on the pass line P1. The conveyance speed may be calculated within the control device 8, or of course, data calculated by a control device separate from the control device 8 may be used.

[0031] As described in relation to FIG. 2, the control device 8 has data on the measured gap amount G1. The heating power calculation unit 41 corrects the heating power using the data on the measured gap amount G1. The correction value of the heating power is set to a larger value as the gap amount G1 is larger. For example, the heating power calculation unit 41 has a table in which correction values for the magnitude of the gap amount G1 are set. The heating power calculation unit 41 extracts and applies a correction value corresponding to the magnitude of the gap amount G1.

[0032] In the specific example shown in FIG. 3, the power command is output to the frequency conversion device 10 via the output voltage correction unit 42. The output voltage correction unit 42 corrects the output voltage according to the power command and the gap amount G1, and generates and outputs a corrected power amount command value.

[0033] The frequency conversion device 10 is a power conversion device using a frequency modulation control method, and sets the frequency for driving the heating coil 4 of the C-type edge heater 1 based on the power command output from the control device 8. The frequency conversion device 10 drives the heating coil 4 at the set frequency.

[0034] The operation of the induction heating device 100 according to the embodiment will be described. The overall length of the steel sheet 5 is sufficiently longer than the lengths L1 and L2 of the warpage. Therefore, the front end and the tail end of the warped steel sheet 5 do not exist in the C-type edge heater 1 at the same time. As shown in Fig. 1, the image of the steel plate 5 captured by the camera 6 is converted into image data, and the warpage amount A is measured by the image processing device 7. The warpage amount A decreases with the progress of the steel plate 5 at the tip of the steel plate 5 and increases with the progress of the steel plate 5 at the trailing end side of the steel plate 5.

[0035] The camera 6 sequentially captures the image of the steel plate 5 as the steel plate 5 progresses to generate and output image data, and the image processing device 7 sequentially measures the warpage amount A as the steel plate 5 progresses.

[0036] The control device 8 calculates the time when the tip of the steel plate 5 enters the C-shaped edge heater 1 based on the tracking data of the tip of the steel plate 5, adds the maximum warpage amount Amax1 at the tip to the reference gap amount B, and sets the set value of the gap amount. The control device 8 drives the AC motor 11 via the drive device 9 and performs feedback control so that the measured gap amount G1 follows the set value of the gap amount (B + Amax1).

[0037] The control device 8 sets the set value of the gap amount using the maximum warpage amount Amax1 until the tip of the steel plate 5 exits the C-shaped edge heater 1 based on the tracking data of the tip of the steel plate 5. That is, while the tip of the steel plate 5 is inside the C-shaped edge heater 1, the gap amount G1 is controlled to a constant value so as to match the added value of the maximum warpage amount Amax1 and the reference gap amount B.

[0038] At the timing when the tip of the steel plate 5 exits the C-shaped edge heater 1, the warpage amount A decreases according to the progress of the steel plate 5. The control device 8 sequentially updates the set value of the gap amount and performs feedback control so that the measured gap amount G1 follows the set value.

[0039] When the steel plate 5 is discharged from the C-shaped edge heater 1 by a length L1 or more from the tip, the warpage of the steel plate 5 in the C-shaped edge heater 1 becomes almost zero, and the actual gap amount G1 is controlled to almost match the reference gap amount B.

[0040] During the period when the gap amount is at the maximum set value (B + Amax1), the actual gap amount G1 adjusted following the set value becomes the maximum value Gmax1 of the gap amount at the tip. The control device 8 inputs the maximum value Gmax1 of the gap amount to the heating power amount calculation unit 41, sets a correction value for the heating power amount corresponding to the maximum value Gmax1, and calculates the corrected heating power amount. The control device 8 corrects the output voltage so as to correspond to the calculated corrected heating power amount by the output voltage correction unit 42, and outputs a power command to the frequency conversion device 10.

[0041] The frequency conversion device 10 sets the frequency according to the power command and supplies power to the heating coil 4. The heating power amount when the gap amount is at the maximum value Gmax1 becomes the maximum power input to the steel plate 5 currently being heated.

[0042] After the tip of the steel plate 5 passes through the C-shaped edge heater 1, the set value of the gap amount is set according to the warpage amount A, and the actual gap amount G1 decreases according to the decrease in the warpage amount A from the maximum value Gmax1. In the control device 8, since the smaller the gap amount G1, the smaller the correction value of the heating power amount is set, during this period, the control device 8 adds a small correction value to the reference gap amount B according to the decrease in the warpage amount A to correct the heating power amount.

[0043] During the period when the steel plate 5 has passed through the C-shaped edge heater 1 by the length L1 of the warpage, the control device 8 adds a correction value corresponding to the minimum gap amount Gmin adjusted following the reference gap amount B to the heating power amount and outputs a power command.

[0044] Regarding the case where the tail end of the steel plate 5 enters the C-shaped edge heater 1, similarly to the above, the set value of the gap amount is set according to the warpage amount A, and a speed command is generated so that the actual gap amount G1 follows the set value, and the size of the gap amount G1 is feedback-controlled.

[0045] The control device 8 corrects the heating power amount according to the size of the actual gap amount G1 and generates a power command value.

[0046] When the tail end of the steel plate 5 enters the C-shaped edge heater 1 according to the tracking data of the tail end of the steel plate 5, the control device 8 controls the maximum value Gmax2 of the gap amount G1 at the tail end so as to follow the magnitude of the warp of the tail end until the tail end exits the C-shaped edge heater 1.

[0047] The control device 8 corrects the heating power amount corresponding to the maximum value Gmax2 of the gap amount, generates a power command, and outputs it.

[0048] In the above description, it is assumed that the timing when the leading end or the tail end enters the C-shaped edge heater 1 and exits the C-shaped edge heater 1 is determined by using the tracking data of the leading end and the tail end. However, it is not limited to this as long as the positions of the leading end and the tail end can be determined. For example, by setting the imaging time in the image data of the image captured by the camera 6 and the leading end position in the imaging reference coordinates, and using the data of the conveyance speed of the steel plate 5 and the length of the steel plate 5, the positions of the leading end and the tail end can be tracked.

[0049] In this way, the induction heating device 100 according to the embodiment can adjust the gap amount G1 according to the warp of the steel plate 5, and heat the steel plate 5 with the heating power amount corresponding to the gap amount G1.

[0050] The effect of the induction heating device 100 according to the embodiment will be described. The induction heating device 100 according to the embodiment includes a camera 6 upstream of the C-shaped edge heater 1. The induction heating device 100 includes an image processing device 7 that captures an image by the camera 6 and calculates the magnitude of the warp of the steel plate 5 entering the C-shaped edge heater 1 based on the generated image data. Further, the induction heating device 100 includes a control device 8 that controls the gap amount G1 based on the data of the magnitude of the warp calculated by the image processing device 7. Thereby, the induction heating device 100 can appropriately control the gap amount G1 according to the magnitude of the warp of the steel plate 5 passing through the C-shaped edge heater 1.

[0051] By tracking the leading and trailing ends of the steel plate 5, the control device 8 can increase the gap amount G1 according to the warp of the steel plate 5 during the period when the leading or trailing end of the steel plate 5 passes through the C-shaped edge heater 1. Therefore, it is possible to prevent accidents such as the warped portion of the steel plate 5 coming into contact with or colliding with the upper inductor 4.

[0052] The control device 8 has a heating power calculation unit 41 that can set a correction value according to the actual gap amount G1. In the heating power calculation unit 41, the larger the gap amount G1, the larger the correction value is set. Therefore, even when the gap amount G1 is increased to avoid the warp of the leading or trailing end of the steel plate 5, sufficient electric power can be applied to the steel plate 5. By suppressing an increase in the load on the downstream device due to insufficient heating of the steel plate 5, it becomes possible to improve the product yield.

[0053] In this way, it is possible to realize an induction heating device that can prevent the collision of the steel plate and sufficiently heat the steel plate even for a warped steel plate.

[0054] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and its equivalent scope.

Explanation of Reference Numerals

[0055] 1…C-type edge heater, 1a…Rotation angle detector, 2…Upper inductor, 3…Core, 4…Heating coil, 5…Steel plate, 6…Camera, 7…Image processing device, 8…Control device, 8a, 21, 24…Limiter, 8b…Position calculation module, 9…Drive device, 10…Frequency conversion device, 11…AC motor, 12…Conveyor roller, 13…Wheel, 14…Lower inductor, 20…Controller, 22…Acceleration / deceleration rate setter, 23…Proportional constant setter, 30…Host computer, 41…Heating power calculation unit, 42…Output voltage correction unit, 100…Induction heating device

Claims

1. A C-shaped edge heater including an upper inductor and a lower inductor provided via a gap so as to heat an edge along the conveyance direction of a steel plate; A camera provided upstream of the C-shaped edge heater, for imaging a steel plate entering the C-shaped edge heater to generate and output image data; An image processing device for performing image processing on the image data to measure and output the magnitude of warpage of each of the leading end and the trailing end of the steel plate; A drive device for driving a motor to move the upper inductor up and down to adjust a gap amount representing the size of the gap between the upper inductor and the lower inductor; A control device for calculating a set value of the gap amount based on the data of the magnitude of warpage, and generating a speed command so that a measured value of the measured gap amount follows the set value and outputting the speed command to the drive device; A power conversion device for supplying power to the upper inductor and the lower inductor according to the amount of heating power input to the steel plate; comprising The control device calculates the amount of heating power based on the measured value and a preset temperature rise value for the steel plate; The control device By tracking the position of the leading end, during the period from when the leading end of the steel plate enters the C-shaped edge heater until it exits, the set value is kept such that the warpage of the leading end is constant; An induction heating device that, by tracking the position of the trailing end, during the period from when the trailing end of the steel plate enters the C-shaped edge heater until it exits, keeps the set value such that the warpage of the trailing end is constant.

2. The control device calculates a heating power amount before correction based on the temperature rise value; determines a correction value for the heating power amount based on the measured value, the correction value having a value that increases as the measured value increases; The induction heating device according to claim 1, wherein the heating power amount is calculated by adding the correction value to the heating power amount before correction.

3. The induction heating device according to claim 1 or 2, wherein the control device sequentially updates the set value in each of a period in which the tip portion passes through the C-shaped edge heater and a period in which the tail portion enters the C-shaped edge heater to generate a speed command.

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