Edge heater control device

Abstract

The present invention provides an edge heater control device that can suppress the temperature drop at the widthwise end of the tail end of a rolled material, even when the leading edge of the rolled material enters the finishing rolling mill and the conveying speed of the rolled material decreases. [Solution] The edge heater control device includes a processing circuit that controls the edge heater installed upstream of the finishing rolling mill. The processing circuit calculates the reference power to be supplied to the edge heater based on the conveying speed of the rolled material at the edge heater. The processing circuit is further configured to calculate a corrected power that increases the reference power in response to the longitudinal center of the rolled material passing through the edge heater, and to supply the corrected power as the final power to the edge heater after the longitudinal center of the rolled material has passed through the edge heater.

Description

Technical Field

[0001] The present disclosure relates to a control device for an edge heater.

Background Art

[0002] In a hot rolling line, an edge heater is often provided upstream of a finishing rolling mill. The edge heater heats both end portions in the width direction of the rolled material, which are at a lower temperature than the central portion in the width direction of the rolled material. By this heating, prevention of quality deterioration such as cracking of the rolled material and prevention of uneven wear of the rolls of the finishing rolling mill can be achieved. As the edge heater, a so-called induction heating type that supplies AC power to an inductor provided near both end portions in the width direction of the rolled material is usually used. A control device for this type of edge heater is known, for example, from Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, usually, the power supplied to the inductor of the edge heater is set based on the speed of a conveyance table corresponding to the conveyance speed of the rolled material in the edge heater. Therefore, when the tip of the rolled material enters the finishing rolling mill, the conveyance speed of the rolled material in the edge heater becomes slow, and accordingly, the supplied power becomes small. As a result, there is a problem that the heating of both end portions in the width direction of the trailing end of the rolled material becomes insufficient and a temperature drop occurs.

[0005] The present disclosure has been made to solve the above-described problems. An object of the present disclosure is to provide a control device for an edge heater capable of suppressing a temperature drop at both end portions in the width direction of the trailing end of a rolled material even when the tip of the rolled material enters the finishing rolling mill and the conveyance speed of the rolled material decreases. [Means for solving the problem]

[0006] The first aspect of this disclosure relates to a control device for an edge heater, comprising a processing circuit for controlling an edge heater installed upstream of a finishing rolling mill. The processing circuit performs the task of calculating a reference power to supply to the edge heater based on the conveying speed of the rolled material at the edge heater. The processing circuit is further configured to perform the tasks of calculating a corrected power that increases the reference power in response to the longitudinal center of the rolled material passing through the edge heater, and supplying the corrected power to the edge heater as the final power after the longitudinal center of the rolled material has passed through the edge heater.

[0007] The second aspect, in addition to the first aspect, has the following further features: The processing circuit further includes a counter that increments the count value from the moment the longitudinal center of the rolled material passes the edge heater. The correction power is calculated by multiplying the reference power by the count value. [Effects of the Invention]

[0008] According to this disclosure, when the longitudinal center of the rolled material passes the edge heater, a correction power greater than the reference power is supplied to the edge heater as the final power. Therefore, even if the leading edge of the rolled material enters the finishing rolling mill and the conveying speed of the rolled material decreases, it is possible to suppress the temperature drop at the widthwise end of the trailing edge of the rolled material. This makes it possible to suppress quality deterioration such as cracking of the rolled material. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example of a hot rolling line to which the edge heater control device according to the embodiment of the present disclosure is applied. [Figure 2] This is a circuit diagram of the processing circuit of the control device for achieving tail end heating control. [Figure 3] This is a time chart to explain the flow of tail end heating control. [Figure 4]This diagram illustrates the effect of tail end heating control compared to conventional control. [Figure 5] This is a conceptual diagram showing an example of the hardware configuration of a control device. [Modes for carrying out the invention]

[0010] Embodiments of this disclosure will be described below with reference to the drawings. Common or corresponding elements in each drawing are denoted by the same reference numerals, and their descriptions are simplified or omitted.

[0011] Figure 1 shows an example of a hot rolling line 2 to which the edge heater control device 1 according to the embodiment of this disclosure is applied. The hot rolling line 2 is equipped with the following main rolling equipment: a heating furnace 21, a roughing mill 22, a finishing mill 24, a cooling device 25, and a winding machine 26. The hot rolling line 2 is also equipped with a transport table 27 for transporting rolled material (steel plate) 20. The transport table 27 is equipped with a speedometer (not shown) and is configured to measure the speed of the transport table 27 corresponding to the transport speed of the rolled material 20. The transport speed of the rolled material 20 can also be measured by plate speedometers (not shown) installed at key locations in the hot rolling line 2.

[0012] The heating furnace 21 heats the rolled material (slab) 20 to a predetermined temperature (for example, 1200°C). The roughing mill 22 has 1 to 3 rolling stands (1 in the example shown in Figure 1) and reverse-rolls the rolled material (slab) 20. The finishing mill 24 is a tandem rolling mill equipped with multiple rolling stands F1 to F7 (7 in the example shown in Figure 1) arranged in parallel in the direction of transport of the rolled material 20. Each rolling stand F1 to F7 is equipped with two upper and lower work rolls 241, two upper and lower backup rolls 242, and a motor 243 for rotating the rolls. The backup rolls 242 are provided with a reduction device 244, which is configured to adjust the gap between the upper and lower work rolls 241 into which the rolled material 20 is gripped. The cooling device 25 cools the rolled material 20 by injecting water into the rolled material (strip) 20 using a cooling bank. The winding machine 26 winds the cooled rolled material 20 into a coil.

[0013] Between the roughing mill 22 and the finishing mill 24, that is, upstream of the finishing mill 24, an edge heater 23 is installed to heat both ends of the rolled material 20 in the width direction. As the edge heater 23, a so-called induction heating type can be used, which supplies AC power from an AC power source (not shown) to an inductor (not shown) provided near both ends of the rolled material 20 in the width direction. Since induction heating type edge heaters 23 are well known, a detailed explanation is omitted here. Various controls, including power control of the edge heater 23, are performed by the processing circuit 10 of the control device 1. The processing circuit 10 receives various rolling information input from the higher-level computer 3, calculates setting data including the set values ​​of each rolling equipment including the edge heater 23, and transmits the calculated design data to the hot rolling line 2, thereby executing the control of each rolling equipment including the edge heater 23. The setting data includes the reference power, which will be described later.

[0014] Here, the power supplied to the edge heater 23 is normally set based on the conveying speed of the rolled material 20 in the edge heater 23 (the speed of the conveying table 27). When the leading edge of the rolled material 20 enters the finishing rolling mill 24, the conveying speed of the rolled material 20 in the edge heater 23 slows down compared to before entry, and consequently, the power supplied to the edge heater 23 decreases. As a result, as shown by the dashed line in Figure 4 described later, the heating of the widthwise end of the tail end of the rolled material 20 becomes insufficient, causing a temperature drop.

[0015] In this embodiment, tail end heating control is performed by the processing circuit 10 of the control device 1. The tail end heating control will be described in detail below. Figure 2 is a circuit diagram of the processing circuit 10 of the control device 1 for realizing tail end heating control.

[0016] As shown in Figure 2, the control device 1 for the edge heater 23 calculates the reference power supplied to the edge heater 23 based on the conveying speed of the rolled material 20 on the edge heater 23. The conveying speed of the rolled material 20 can be determined from the speed of the conveying table 27. The AND circuit turns on the tail end heating control when a setup signal for the edge heater 23 is input from the host computer 3 and the longitudinal center of the rolled material 20 passes the edge heater 23. The setup signal is a signal to prepare the edge heater 23 for heating. The position of the rolled material 20 can be determined using known tracking techniques or load sensors.

[0017] The tail heating control is OFF until the longitudinal center of the rolled material 20 passes the edge heater 23. When the tail heating control is OFF, the counter count value is held at "1" without being incremented. In this case, the reference power is supplied to the edge heater 23 as is without correction (same as conventional control).

[0018] When the end heating control is turned on, the count value of the counter is incremented by a predetermined amount of change (gain). By multiplying the count value of the counter by the reference power, the reference power is corrected to increase. The multiplication value of the count value and the reference power is output as corrected power after the change rate is limited by the DLM circuit and the upper limit is limited by the LMT circuit. As a result, corrected power greater than the reference power is supplied to the edge heater 23 as the final power.

[0019] Note that when the end heating control is OFF or the initial flag is turned on, the OR circuit turns on the counter reset signal. When the counter reset signal is turned on, the count value of the counter is reset to "1".

[0020] Figure 3 is a time chart for explaining the flow of the end heating control. At time t1 in Figure 3, when the initial flag is turned on, the counter reset signal is turned on and the count value of the counter is reset to "1". Next, at time t2, the setup signal is turned on. After that, at time t3, the speed of the conveyance table 27 corresponding to the conveyance speed of the rolled material 20 increases. At this time, since the end heating control is OFF, the reference power calculated based on the speed of the conveyance table 27 is supplied to the edge heater 23 as the final power. At time t4, when the tip of the rolled material 20 enters the finishing rolling machine 24, the speed of the conveyance table 27 is gradually decreased under the control of the finishing rolling machine 24, and accordingly, the reference power as the final power also gradually decreases. After time t5, the speed of the conveyance table 27 becomes constant.

[0021] At time t6, when the central portion in the longitudinal direction of the rolled material 20 passes through the edge heater 23, the tail-end heating control is turned on. As a result, the increment (count-up) of the counter value of the counter is started. By multiplying the incremented counter value (>1) by the reference power, the correction power is calculated, and the calculated correction power is supplied to the edge heater 23 as the final power. That is, a bias is applied to the reference power, and the final power increases. The change amount (gain) of the counter can be set so that the tail end of the rolled material 20 is sufficiently heated by the edge heater 23, that is, so that the correction power as the final power reaches the upper limit value at time t7 when the tail end of the rolled material 20 has not passed through the edge heater 23.

[0022] At time t8, when the tail end of the rolled material 20 passes through the edge heater 23, the tail-end heating control is turned off. As a result, the counter reset signal is turned on, and the count value of the counter is reset to "1". Also, the setup signal is turned off.

[0023] FIG. 4 is a diagram for explaining the effect of the tail-end heating control in comparison with the conventional control. FIG. 4 shows the temperature distribution along the longitudinal direction of the widthwise end portion of the rolled material 20 corresponding to the power supplied to the edge heater 23. As shown by the solid line in FIG. 4, from the tip end to the central portion in the longitudinal direction of the rolled material 20, the temperature is the same as that of the conventional control shown by the broken line, but from the central portion in the longitudinal direction to the tail end, the temperature can be raised more than the conventional control.

[0024] As described above, according to the present embodiment, when the central portion in the longitudinal direction of the rolled material 20 passes through the edge heater 23, a correction power larger than the reference power is supplied to the edge heater 23 as the final power. Therefore, even if the tip end of the rolled material 20 enters the finishing rolling mill 24 and the conveyance speed of the rolled material 20 decreases, it is possible to suppress the temperature drop of the widthwise end portion of the tail end of the rolled material 20. Thereby, quality deterioration such as cracking of the rolled material 20 can be suppressed.

[0025] Figure 5 shows an example of the hardware configuration of the processing circuit 10 of the control device 1. Each of the functions of the control device 1 described above can be realized by the processing circuit 10 having the configuration shown in Figure 5. This processing circuit 10 may be dedicated hardware 10a. This processing circuit 10 may also include a processor 10b and memory 10c. This processing circuit 10 may be partially formed as dedicated hardware 10a and further include a processor 10b and memory 10c. In the example shown in Figure 5, a part of the processing circuit 10 is formed as dedicated hardware 10a, and the processing circuit 10 also includes a processor 10b and memory 10c. The processing circuit 10 may include at least one dedicated hardware 10a. In this case, the processing circuit 10 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. The processing circuit 10 may also include at least one processor 10b and at least one memory 10c. In this case, each function of the control device 1 is realized by software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in memory 10c. The processor 10b realizes each function of the control device 1 by reading and executing the programs stored in memory 10c. The processor 10b is also called a CPU (Central Processing Unit), processing unit, arithmetic unit, microprocessor, microcomputer, or DSP. Memory 10c is a storage device such as a non-volatile or volatile semiconductor memory, such as RAM, ROM, flash memory, EPROM, or EEPROM. Memory 10c can also serve as a database DB. In this way, the processing circuit 10 can realize each function of the control device 1 through hardware, software, firmware, or a combination thereof.

[0026] Although embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments and can be implemented in various modified forms without departing from the spirit of the present disclosure. In the above embodiments, the increment of the counter count value starts at the same time that the tail end heating control is turned ON, but it may also be configured so that the increment starts after a predetermined time has elapsed after the tail end heating control is turned ON. This makes it possible to save energy. Moreover, since the temperature near the longitudinal center of the rolled material 20 does not drop as easily as the tail end, delaying the correction of the reference power does not adversely affect the tail end temperature of the rolled material 20.

[0027] Furthermore, when referring to the number, quantity, amount, range, etc., of each element in the embodiments described above, this disclosure is not limited to the number referred to, unless otherwise explicitly stated or clearly defined in principle. Also, the structures, etc., described in the embodiments described above are not necessarily essential to this invention, unless otherwise explicitly stated or clearly defined in principle. [Explanation of symbols]

[0028] 1...Control device, 10...Processing circuit, 10a...Dedicated hardware, 10b...Processor, 10c...Memory, 2...Hot rolling line, 20...Rolled material, 21...Heating furnace, 22...Roughing mill, 23...Edge heater, 24...Finishing mill, 25...Cooling device, 26...Winding machine, 27...Conveyor table, 3...Host computer

Claims

1. An edge heater control device comprising a processing circuit for controlling an edge heater installed on the upstream side of a finishing rolling mill, The processing circuit performs the calculation of a reference power to be supplied to the edge heater based on the conveying speed of the rolled material at the edge heater, The aforementioned processing circuit is In response to the fact that the longitudinal center of the rolled material has passed through the edge heater, a corrected power is calculated to increase the reference power, After the longitudinal center of the rolled material passes through the edge heater, the correction power is supplied to the edge heater as the final power. A control device for an edge heater configured to perform the following further.

2. A control device for an edge heater according to claim 1, The aforementioned processing circuit is The rolling material is further provided with a counter that increments a count value from the moment the longitudinal center of the rolled material passes the edge heater, The correction power is calculated by multiplying the reference power by the count value in the control device for the edge heater.

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