JP2005118803A - Device and method for producing metallic sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metallic sheet of high quality having a uniform sheet thickness and free from wrinkles, in a device where the metallic sheet is produced from molten metal using a pair of cooling rollers, by measuring the positions of the meniscuses in molten metal on the cooling rollers and suppressing the variation in the positions of the meniscuses. <P>SOLUTION: Eddy current sensors are buried in the slit of a tundish feeding molten metal to cooling rollers. The distances to the meniscuses are measured by the eddy current sensors. When the positions of the meniscuses are varied, any of the rotary speed of the cooling rollers, the cooling capacity of the cooling rollers, the temperature of the molten metal and the amount of the molten metal to be fed is controlled, thus, the variation in the positions of the meniscuses is suppressed, and the metal sheet of high quality can be obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a metal sheet manufacturing technique. In particular, the present invention relates to a technique for manufacturing a metal sheet having a uniform thickness by passing a molten metal through a gap between a pair of cooling rollers.

  In order to manufacture a metal sheet from a molten metal, a technique using a pair of cooling rollers is known. The pair of cooling rollers rotate with a constant gap. When the molten metal is supplied to the entrance of the gap between the cooling rollers, the molten metal is fed into the gap by the rotation of the cooling roller. While passing through the gap between the cooling rollers, the molten metal is cooled and solidified to form a metal sheet and is sent out from the cooling roller. With this technique, a metal sheet having a certain thickness can be continuously produced.

The molten metal immediately before entering the gap between the cooling rollers forms a meniscus that spreads toward the cooling roller due to surface tension. The position of the meniscus varies depending on various factors such as the rotational speed of the cooling roller, the cooling capacity of the cooling roller, the temperature of the molten metal, and the amount of molten metal delivered. When the position of the meniscus changes, the thickness of the metal sheet to be manufactured changes so as to wave, or striped wrinkles are generated on the surface of the metal sheet. The uneven thickness of the metal sheet and the striped wrinkles formed on the surface are very difficult to remove in the subsequent processing step (for example, rolling step), which causes the quality of the metal sheet to deteriorate. Yes.
A technique for preventing fluctuations in plate thickness is disclosed in Patent Document 1. In the technique of Patent Document 1, a pair of cooling rollers are arranged horizontally, and a molten metal is supplied to the upper portion of the gap between the cooling rollers from a tundish nozzle installed at the upper portion of the gap between the cooling rollers. The supplied molten metal forms a hot water pool between the cooling rollers. In the technique of Patent Document 1, the height of the liquid level of the hot water puddle is measured using a sensor, and the height of the liquid level of the hot water puddle is controlled to a constant height based on the measurement result. The quality of the metal sheet is kept constant by feedback-controlling the level of the liquid level in the hot water pool.
Japanese Patent Laid-Open No. 07-132349

In the technique of Patent Document 1, a molten metal pool is formed in the upper part of the gap between a pair of cooling rollers, and feedback control is performed so that the liquid level of the pool is maintained constant. By adopting a system in which a pair of cooling rollers are arranged horizontally and a pool of molten metal is formed at the top of the gap, it is easy to measure the liquid level and feedback so that the liquid level is kept constant. Can be controlled. However, when forming a puddle in the upper part of the gap between the cooling rollers, there is a problem that a defective molding is likely to occur at the start of molding when the puddle starts to form and at the end of molding when the puddle is eliminated. Exists.
A technique has been developed in which molten metal is sent directly from a slit of a Danish to a gap between cooling rollers without forming a hot water pool. In this method, since it is not necessary to form a hot water pool, there is little waste at the start of molding and at the end of molding. The molten metal delivered from the slit of the Danish toward the gap between the cooling rollers spreads toward the cooling roller by surface tension immediately before being fed into the gap between the pair of cooling rollers, thereby forming a meniscus. As described above, the position of the meniscus is very important for maintaining the thickness of the metal sheet to be formed constant. However, in the system in which the molten metal is sent directly from the slit of the Dandy into the gap between the cooling rollers, it is necessary to arrange the Danish slit and the pair of cooling rollers very close to each other, and the position of the meniscus is monitored by a camera. It is difficult to install a sensor for measuring the position of the meniscus. At present, the position of the meniscus of the molten metal cannot be measured. With the technology to send molten metal directly from the slit of the Dandy into the gap between the cooling rollers, the position of the meniscus cannot be measured and controlled to be maintained at a constant position, and a metal sheet with a uniform plate thickness is produced. It has become an obstacle.

In an apparatus for manufacturing a metal sheet by directly sending molten metal from the Dandy slit to the gap between the cooling rollers, the position of the meniscus of the molten metal immediately before entering the gap between the cooling rollers is measured and based on the measurement result. Therefore, there is a need for a technique that feedback-controls the operating conditions of the metal sheet manufacturing apparatus and suppresses changes in the meniscus position. If fluctuations in the meniscus position can be suppressed, the thickness of the metal sheet to be manufactured can be made uniform. Moreover, a wrinkle does not generate | occur | produce on the metal sheet surface but a metal sheet with high surface quality can be obtained.
The present invention has been made in view of the above problems, and when manufacturing a metal sheet from a molten metal, accurately measure the position of the meniscus of the molten metal, feedback control the operating conditions based on the measurement results, The present invention provides a manufacturing apparatus and a manufacturing method capable of manufacturing a high-quality metal sheet having a uniform plate thickness and no wrinkles on the surface by suppressing fluctuations in the position of the meniscus.

  The apparatus of this invention is an apparatus which manufactures a metal sheet from a molten metal, Comprising: The following means are provided. That is, a pair of cooling rollers opposed to each other with a gap, a dandy that feeds the molten metal from the slit toward the gap, and a meniscus where the molten metal delivered from the slit spreads toward the pair of cooling rollers Based on the output of the eddy current sensor and the eddy current sensor, increase or decrease at least one of the rotation speed of the cooling roller, the cooling capacity of the cooling roller, the temperature of the molten metal, and the delivery amount of the molten metal It has a controller to adjust.

The metal sheet manufacturing apparatus of the present invention includes an eddy current sensor. The eddy current sensor can be miniaturized and can be arranged at a position where the distance to the meniscus can be measured even when the Danish and the pair of cooling rollers are arranged close to each other. In addition, it can withstand the high temperatures resulting from molten metal. If an eddy current sensor is used, the position of the meniscus can be measured and the change in the position of the meniscus can be known.
The position of the meniscus can be adjusted by increasing / decreasing the value of any one of the rotation speed of the cooling roller, the cooling capacity of the cooling roller, the temperature of the molten metal, and the delivery amount of the molten metal. When a change in the meniscus position is detected, it is possible to keep the meniscus position substantially constant by adjusting the operating conditions of the apparatus so as to suppress the change by the controller. By stabilizing the position of the meniscus, the thickness of the metal sheet to be produced can be made uniform, and a high-quality metal sheet having no wrinkles on the surface can be obtained.

  It is preferable that the rotational speed of the pair of cooling rollers can be controlled independently, and eddy current sensors are provided on both the front and back sides of the slit. The controller increases or decreases the rotational speed of the front cooling roller based on the output of the front eddy current sensor, and adjusts the rotational speed of the back cooling roller based on the output of the back eddy current sensor.

  Knowing the position of the meniscus of the molten metal that spreads toward the front cooling roller and the position of the meniscus of the molten metal that spreads toward the back cooling roller by providing eddy current sensors on both sides of the slit of the tundish Can do. When the position of the meniscus that spreads to the front side and the position of the meniscus that spreads to the back side are different, the rotation speed of the front cooling roller and the rotation speed of the back cooling roller are controlled independently, so that the positions of both the front and back meniscuses are respectively It is possible to maintain a constant position.

  The present invention has also created a method for producing a high-quality metal sheet having a uniform thickness and no wrinkles on the surface from a molten metal. This manufacturing method includes a step of measuring a distance to the meniscus using an eddy current flowing in a meniscus in which a molten metal delivered from a slit spreads toward a pair of cooling rollers, and cooling based on the measured distance. And a step of feedback-controlling the distance to the meniscus by adjusting at least one of the rotational speed of the roller, the cooling capacity of the cooling roller, the temperature of the molten metal, and the feed amount of the molten metal.

  According to the metal sheet manufacturing apparatus and method of the present invention, the molten metal is sent from the slit to the gap between the pair of cooling rollers, and the molten metal fed into the gap is cooled by the cooling roller. During manufacturing, the position of the meniscus where the molten metal spreads toward the cooling roller can be measured by an eddy current sensor. By knowing the position of the meniscus from the measurement results of the eddy current sensor, and adjusting the value of any of the rotation speed of the cooling roller, the cooling capacity of the cooling roller, the temperature of the molten metal, and the delivery amount of the molten metal based on that Therefore, it is possible to suppress a change in the position of the meniscus and keep the position of the meniscus substantially constant. By stabilizing the position of the meniscus, the thickness of the metal sheet to be produced can be made uniform, and a high-quality metal sheet having no wrinkles on the surface can be obtained.

Below, the best form for implementing the manufacturing apparatus and manufacturing method of the metal sheet which concern on this application is listed.
(Mode 1) A pair of cooling rollers are arranged vertically. A gap having a predetermined interval is provided between the upper cooling roller and the lower cooling roller.
(Mode 2) Cooling water passes through the cooling water passage inside the cooling roller. A valve is provided in the cooling water passage to control the flow rate of the cooling water per unit time. The cooling capacity of the cooling roller is adjusted by the flow rate of the cooling water.
(Mode 3) A dundish is disposed on the side of a pair of cooling rollers disposed above and below. A slit having a width substantially the same as the width of the cooling roller is opened toward the gap between the cooling rollers at the tip of the dandy, and the molten metal fed from the slit is fed into the gap between the cooling rollers.
(Mode 4) The eddy current sensor is embedded at a plurality of locations along the slit of the Danish.
(Embodiment 5) At least one eddy current sensor is embedded on both the front and back sides of the Danish with the slit interposed therebetween.
(Mode 6) The controller increases / decreases the cooling capacity of the upper cooling roller based on the output of the eddy current sensor on the upper side of the slit, and controls the lower cooling roller based on the output of the eddy current sensor on the lower side of the slit. Increase or decrease the cooling capacity.
(Mode 7) The eddy current sensor is arranged at a position corresponding to the passage of the cooling water of the cooling roller. The controller independently controls the flow rate of the cooling water at the position corresponding to the eddy current sensor based on the position data of the meniscus output from the eddy current sensor.

Embodiments of a metal sheet manufacturing method and a manufacturing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.
First Example FIG. 1 schematically shows the configuration of a metal sheet manufacturing apparatus according to a first example of the present invention.
In the metal sheet manufacturing apparatus of the present embodiment, a pair of cooling rollers 2 and 22 are arranged vertically. A gap of a predetermined distance is provided between the cooling roller 2 and the cooling roller 22. A cooling water passage 4 is provided inside the upper cooling roller 2, and a predetermined amount of cooling water is supplied from a cooling water valve 8. A cooling water passage 24 is provided inside the lower cooling roller 22, and a predetermined amount of cooling water is supplied from the cooling water valve 28. A motor 6 is connected to the cooling roller 2, and a motor 26 is connected to the cooling roller 22. The motors 6 and 26 cause the cooling rollers 2 and 22 to rotate in a direction in which the molten metal supplied to the gap is fed into the gap. That is, the cooling roller 2 rotates clockwise in FIG. 1, and the cooling roller 22 rotates counterclockwise. The rotational speeds of the motors 6 and 26 can be controlled independently, and the rotational speeds of the cooling rollers 2 and 22 vary depending on the rotational speeds of the motors 6 and 26.

Dandysh 50 is made of a heat-resistant ceramic and can store molten metal 46. The Dandysh 50 includes a pressurizing means 42 that pressurizes the molten metal 46 and feeds it toward the gap between the cooling rollers 2 and 22, and a heater 44 that heats the molten metal 46 to a predetermined temperature.
A slit 52 is opened at the tip of the Danish 50. The width of the slit 52 is substantially the same as the width of the cooling rollers 2 and 22. The dundish 50 is disposed on the side of the cooling rollers 2 and 22, and the molten metal 46 fed from the slit 52 reaches the outer peripheral surface of the cooling rollers 2 and 22. The dundish 50 and the cooling rollers 2 and 22 of this embodiment are arranged very close to each other, and the gap between the cooling roller 2 and the cooling roller 22 is observed from the outside, or the cooling rollers 2 and 22 and the dundish 50 are connected to each other. It is very difficult to insert a sensor or the like between them.
The molten metal 46 sent out from the slit 52 toward the gap between the cooling rollers 2 and 22 spreads toward the outer peripheral surface of the cooling rollers 2 and 22 due to surface tension, and is sent into the gap as the cooling rollers 2 and 22 rotate. . The molten metal 46 fed into the gap starts to solidify from the portion in contact with the cooling rollers 2 and 22, and solidifies all the way to the center to form a metal sheet 48 and is sent out from the gap between the cooling rollers 2 and 22.

  Immediately before entering the gap between the cooling rollers 2 and 22, the molten metal 46 sent toward the gap between the cooling rollers 2 and 22 spreads toward the outer periphery of the cooling rollers 2 and 22 to form meniscuses 54 and 56. To do. The positions of the meniscuses 54 and 56 are the temperature of the molten metal 46, the pressing force of the pressurizing means 42 (this changes the feed amount of the molten metal 46), the rotational speed of the cooling rollers 2 and 22, and the cooling rollers 2 and 22 Fluctuates due to changes in cooling capacity. In addition, the meniscus 54 expanding toward the cooling roller 2 and the meniscus 56 expanding toward the cooling roller 22 may fluctuate at different positions.

The sensor coil 10 of the eddy current sensor 60 is embedded above the slit 52 of the tundish 50. The sensor coil 30 of the eddy current sensor 62 is embedded below the slit 52. The sensor coils 10 and 30 are coreless coils with high heat resistance.
The eddy current sensor 60 supplies a high-frequency current to the sensor coil 10 from the AC power supply 12. The sensor coil 10 generates a high frequency magnetic field when a high frequency current flows. Due to the high-frequency magnetic field of the sensor coil 10, an eddy current perpendicular to the direction in which the magnetic flux passes flows on the surface of the meniscus 54. When the distance between the meniscus 54 and the sensor coil 10 is short, the generated eddy current increases, and the impedance of the sensor coil 10 increases due to the action of the eddy current. When the distance between the meniscus 54 and the sensor coil 10 is long, the eddy current generated becomes small and the impedance of the sensor coil 10 becomes small. In this way, the distance between the meniscus 54 and the sensor coil 10 is measured as an impedance value by the eddy current sensor 60.
Similarly, the eddy current sensor 62 generates an eddy current in the meniscus 56 by the high-frequency magnetic field of the sensor coil 30, and measures the distance between the meniscus 56 and the sensor coil 30 as an impedance value.
The impedance meter 14 of the eddy current sensor 60 converts the measurement result of the impedance of the sensor coil 10 into the distance between the sensor coil 10 and the meniscus 54 and outputs it to the controller 40. The impedance meter 34 of the eddy current sensor 62 converts the measurement result of the impedance of the sensor coil 30 into the distance between the sensor coil 30 and the meniscus 56 and outputs the distance to the controller 40.

Since the distance between the cooling rollers 2 and 22 and the dundish 50 is fixed and the eddy current sensors 60 and 62 are embedded in the tundish 50, the distance between the measured sensor coils 10 and 30 and the meniscus 54 and 56 is The change indicates a change in the position of the meniscus 54, 56.
The controller 40 receives changes in the distance between the meniscus 54 and the sensor coil 10 and changes in the distance between the meniscus 56 and the sensor coil 30 from the eddy current sensors 60 and 62. The controller 40 monitors the change in distance, and controls the operating conditions of the cooling rollers 2 and 22 to suppress the change when the position of the meniscus 54 and 56 changes beyond the allowable range.

The contents of control by the controller 40 will be described with reference to the flowchart of FIG. The controller 40 starts control simultaneously with the start of operation. First, the standard of the distance between the meniscus 54 and 56 and the sensor coils 10 and 30 is read as the maximum distance value Lmax and the minimum distance value Lmin (step S2). In the standard value, the positions of the meniscus 54 and 56 where the thickness of the metal sheet 48 to be manufactured is constant and the surface is not wrinkled are defined as the distance from the sensor coils 10 and 30.
Next, the controller 40 reads the distance to the meniscus 54, 56 output from the eddy current sensors 60, 62 in step S4.

In step S6 and subsequent steps, the controller 40 makes a determination by comparing the distance standard value of the meniscus 54, 56 read in step S2 with the distance measurement value read in step S4. As a result of the comparison determination, when it becomes clear that the positions of the meniscuses 54 and 56 have moved beyond the standard value, the controller 40 controls the rotational speeds of the motors 6 and 26 to control the rotational speeds of the cooling rollers 2 and 22. It adjusts and suppresses the change of the position of the meniscus 54,56.
In step S6, the controller 40 compares the measured value of the distance between the meniscus 54 and the sensor coil 10 with the minimum value Lmin of the distance standard. When the measured distance value is smaller than the standard minimum value Lmin, step S6 becomes no and the control of step S8 is performed. At this time, the meniscus 54 has spread too far to the outer periphery of the cooling roller 2 and is too close to the sensor coil 10. In step S8, the controller 40 increases the rotational speed of the motor 6. Increasing the rotation speed of the motor 6 increases the rotation speed of the cooling roller 2, and the cooling roller 2 feeds the molten metal 46 around the gap quickly into the gap. Return to the position of the distance. .
If the measured value of the meniscus 54 distance is greater than the standard minimum value Lmin, step S6 is YES. The control of the controller 40 proceeds to step S10 and performs the next comparison determination.

  In step S10, the controller 40 compares the measured value of the distance between the meniscus 54 and the sensor coil 10 with the maximum value Lmax of the distance standard. When the measured value of the distance is larger than the standard maximum value Lmax, step S10 becomes no and the control of step S12 is performed. At this time, the meniscus 54 enters the gap between the cooling rollers 2 and 22 too much, and the distance from the sensor coil 10 is too long. The controller 40 decreases the rotation speed of the motor 6 in step S12. Lowering the rotational speed of the motor 6 slows the rotational speed of the cooling roller 2 and slows the speed at which the cooling roller 2 feeds the molten metal 46 around the gap, so that the meniscus 54 spreads to an appropriate position, Return to the distance within. After completing the control in step S12, the controller 40 proceeds to step S14 and performs the next comparison determination. When the measured value of the meniscus 54 distance is smaller than the standard maximum value Lmax, step S10 is YES. The control of the controller 40 proceeds to step S14 and performs the next comparison determination.

  In step S14, the controller 40 compares the measured value of the distance between the meniscus 56 and the sensor coil 30 with the minimum value Lmin of the distance standard. When the measured value is smaller than the standard minimum value Lmin, step S14 becomes no and the control of the controller 40 proceeds to step S16. In step S <b> 16, the controller 40 increases the rotation speed of the motor 26. By this control, the meniscus 56 that has been expanded too much is returned to a position within a standard distance. When the measured value is larger than the standard minimum value Lmin, step S14 becomes yes and the control of the controller 40 proceeds to step S18.

  In step S18, the controller 40 compares the measured value of the distance between the meniscus 56 and the sensor coil 30 with the maximum value Lmax of the distance standard. When the measured value is larger than the standard maximum value Lmax, S18 becomes no, and the control of the controller 40 proceeds to step S20. In step S <b> 20, the controller 40 decreases the rotation speed of the motor 26. By this control, the meniscus 56 that has entered the gap too much returns to a position within the standard distance. When the measured distance value is smaller than the standard maximum value Lmax, the answer to step S20 is yes, and the control of the controller 40 proceeds to step S22.

If the distance between the meniscus 54 and 56 and the sensor coils 10 and 30 deviates from the standard value due to the determination and control processing performed by the controller 40 in steps S6 to S20, the rotational speed of the cooling rolls 2 and 22 immediately increases. Adjusted to keep meniscus 54, 56 in a preferred position. The manufactured metal sheet 48 has a uniform plate thickness and no wrinkles on the surface.
In step S22, the controller 40 checks whether or not a device stop command has been issued. When the device stop command is issued, the process is terminated. When the apparatus stop command is not issued, the process returns to the process of step S4, the measurement result of the distance between the meniscus 54, 56 and the sensor coils 10, 30 is newly read, and the determination and control processes are repeated.

The controller 40 controls the cooling capacity of the cooling rollers 2 and 22 instead of controlling the rotational speed of the motors 6 and 26 when the meniscuses 54 and 56 are moved to non-standard positions. You may make it suppress a fluctuation | variation.
When the distance of the meniscus 54 becomes larger than the standard maximum value, the controller 40 throttles the cooling water valve 8. Then, the amount of cooling water passing through the cooling water passage 4 is reduced. Since the cooling roller 2 with a reduced amount of cooling water has a reduced ability to cool the molten metal 46, the molten metal 46 on the side in contact with the cooling roller 2 is sent to the gap between the cooling rollers 2 and 22 with low viscosity. Is included. For this reason, the meniscus 54 easily spreads to the outer peripheral portion of the cooling roller 2, and the position of the meniscus 54 can be returned to a position within the standard. On the contrary, when the distance of the meniscus 54 becomes smaller than the minimum value of the standard, the opening amount of the cooling water valve 8 is increased. Then, the amount of cooling water increases, and the cooling roller 2 has an increased ability to cool the molten metal 46. The molten metal 46 in contact with the cooling roller 2 whose cooling capacity has been increased has increased viscosity and is difficult to spread around the outer periphery of the cooling roller 2. The position of the meniscus 54 that has spread too much on the outer periphery of the cooling roller 2 can be returned to a position within the standard. By performing the same control for the cooling water valve 28 of the cooling roller 22, the fluctuation of the meniscus 56 can be suppressed.

  When the meniscus 54 or the meniscus 56 changes to a non-standard position, the controller 40 rotates the motors 8 and 28 connected to the cooling rollers 2 and 22, and supplies the cooling water to the cooling rollers 2 and 22. The opening amounts of the valves 8 and 28 may be controlled together. If the rotation speed and the cooling capacity of the cooling rollers 2 and 22 are changed at the same time, fluctuations in the meniscus 54 and 56 are more quickly suppressed and kept at a position within the standard.

  Two or more eddy current sensors can be embedded in the upper and lower portions along the slit 52 of the tundish 50, respectively. FIG. 3 shows a part of a tundish 50 in which a plurality of eddy current sensors are embedded. The eddy current sensors 60 a and 60 b are embedded above the slit 52, and the eddy current sensors 62 a and 62 b are embedded below the slit 52. The controller 40 averages the distance values of the meniscus 54 output from all the eddy current sensors arranged above the slit 52, and controls the rotational speed or cooling capacity of the cooling roller 2 based on the average value. it can. Similarly, the distance value of the meniscus 56 output from all the eddy current sensors arranged on the lower side of the slit 52 is averaged, and the rotational speed or cooling capacity of the cooling roller 22 is controlled based on the average value. it can. By measuring the positions of the meniscuses 54 and 56 at a plurality of locations, it is possible to know the fluctuations in the positions of the meniscuses 54 and 56 with high accuracy and control the positions.

In the metal sheet manufacturing apparatus of the present embodiment, the molten metal 46 is fed into the gap between the cooling rollers 2 and 22 from the slit 52 of the adjacent dundish 50. By using the eddy current sensors 10 and 30 embedded above and below the slit 52, it becomes possible to measure the positions of the meniscuses 54 and 56 of the molten metal 46, which has heretofore been difficult to measure. It is possible to know the fluctuations of The controller 40 that reads the fluctuations in the positions of the meniscuses 54 and 56 controls the rotational speed and / or cooling capacity of the cooling rollers 2 and 22, thereby suppressing the fluctuations in the positions of the meniscuses 54 and 56, and the manufactured metal. The uneven thickness of the sheet 48 and the generation of wrinkles on the surface can be suppressed. As a result, a high-quality metal sheet 48 is manufactured.
The controller 40 of this embodiment controls the operating condition of the upper cooling roller 2 based on the data of the eddy current sensor 10 that measured the position of the meniscus 54, and uses the data of the eddy current sensor 30 that measured the position of the meniscus 56. Based on this, the operating conditions of the lower cooling roller 22 are controlled. By controlling the operating conditions of the cooling roller 2 and the cooling roller 22 independently, the positions of the meniscus 54 and the meniscus 56 that have fluctuated to different positions can be adjusted at the same time and kept at a position within the standard.

(2nd Example) The structure of the manufacturing apparatus of the metal sheet of a present Example is the same as 1st Example, The same code | symbol is provided and duplication description is abbreviate | omitted. The contents of control by the controller 40 of this embodiment will be described with reference to the flowchart of FIG.
The controller 40 not only determines the measurement result of the distance between the meniscus 54, 56 and the sensor coils 10, 30, but also determines the average value of the distance between the meniscus 54 and the meniscus 56, compares this value with the standard value, and determines it. . If any of the distances between the meniscuses 54 and 56 falls outside the standard as a result of the determination, the opening amounts of the cooling water valves 8 and 28 are controlled to suppress fluctuations in the meniscuses 54 and 56. When the average value of the distance between the meniscus 54 and the meniscus 56 becomes out of specification, the temperature of the heater 44 of the tundish 50 is controlled to suppress fluctuations in the meniscus 54 and 56.

  When the control is started, the controller 40 of the present embodiment reads the standard of the distance between the meniscus 54, 56 and the sensor coil 10, 30 as the maximum allowable distance value Lmax and the minimum distance value Lmin ( Step S32). Next, the controller 40 reads the distance to the meniscus 54, 56 output from the eddy current sensors 60, 62 in step S34. The controller 40 obtains the average value Lave of the read distance values of the meniscus 54, 56 (step S36).

In step S38 and subsequent steps, the controller 40 advances the comparison determination between the standard value of the distance between the meniscus 54 and 56, the distance measurement result, and the average value Lave of the measurement result.
As a result of the determination in step S38 and step S42, when it becomes clear that the position of the meniscus 54 has moved beyond the standard value, the controller 40 adjusts the opening amount of the cooling water valve 8 by the control in step S40 and step S44. Thus, the movement of the meniscus 54 is suppressed. As a result of the determination in step S46 and step S50, when it becomes clear that the position of the meniscus 56 has moved beyond the standard value, the controller 40 adjusts the opening amount of the cooling water valve 28 by the control in step S48 and step S52. Thus, the movement of the meniscus 56 is suppressed.

In step S54, the controller 40 compares the average value Level of the distance with the standard minimum value Lmin. When the average value Lave of the distance is smaller than the standard minimum value Lmin, step S54 becomes no and the control of step S56 is performed. At this time, the positions of the meniscus 54 and 56 are too wide on the outer periphery of the cooling roller and are too close to the sensor coils 10 and 30. In step S56, the controller 40 decreases the temperature of the heater 44 of the Danish 50. When the temperature of the heater 44 is lowered, the viscosity of the molten metal 46 of the Danish 50 is increased, the expansion of the entire meniscus 54, 56 is suppressed, and the sensor coil 10, 30 returns to a position within the standard. .
When the average value Lave of the distance is larger than the standard minimum value Lmin, step S54 is YES. Control of the controller 40 proceeds to step S58.

In step S58, the controller 40 compares the average value Level of the distance with the standard maximum value Lmax. When the average value Lave of the distance is larger than the standard maximum value Lmax, step S58 becomes no and the control of step S60 is performed. At this time, the position of the entire meniscus 54, 56 enters the gap between the cooling rollers 2, 22 too much, and the distance from the sensor coils 10, 30 is longer than the standard value. The controller 40 increases the temperature of the heater 44 and decreases the viscosity of the molten metal 46 in step S60. Since the molten metal 46 easily spreads on the cooling roller, the entire meniscus 54, 56 returns to an appropriate position where the distance from the sensor coils 10, 30 is within the standard.
When the average value Lave of the distance is smaller than the standard maximum value Lmax, step S58 is YES. When both steps S54 and S58 are YES, the controller 40 does not change the temperature of the heater 44. At this time, the distances from the sensor coils 10 and 30 of the meniscus 54 and 56 are maintained within the standard as a whole.
Control of the controller 40 proceeds to step S62. If a device stop command is issued in step S62, the controller 40 ends the process. When the command to stop the apparatus is not issued, the process returns to step S34, and the measurement result of the distance between the meniscus 54, 56 and the sensor coils 10, 30 is newly read.

When the average value of the distance between the meniscuses 54 and 56 becomes out of specification, the controller 40 controls the pressure of the pressurizing means 42 instead of controlling the temperature of the heater 44 of the tundish 50, and controls the meniscus 54 and 56. You may make it suppress a fluctuation | variation.
The controller 40 reduces the amount of the molten metal 46 delivered from the slit 52 by reducing the pressure of the pressurizing means 42 when the average distance between the meniscuses 54 and 56 is smaller than the minimum value of the standard. Thereby, the expansion of the meniscus 54, 56 can be suppressed. When the average value of the distance between the meniscuses 54 and 56 is larger than the standard maximum value, the amount of the molten metal 46 delivered from the slit 52 is increased by increasing the pressure of the pressurizing means 42. As a result, the meniscus 54, 56 can be expanded.

  The controller 40 of this embodiment determines the average value Lave of the distances of the meniscus 54 and 56 in addition to the single measured value of the distance of the meniscus 54 and 56 by comparing with the standard values Lmin and Lmax. . When the average value Lave of the distance is out of the range of the standard value, the operation conditions of the heater 44 and / or the pressurizing means 42 of the tundish 50 are controlled to keep the positions of the meniscus 54 and 56 within the standard. be able to. Further, the position of the meniscus 54, 56 is individually specified by controlling the number of rotations and / or the cooling capacity of the cooling rollers 2, 22 from the result of comparison between the measured value of the meniscus 54, 56 and the standard value. Can be kept inside.

Third Embodiment FIG. 5 shows a list of control contents performed by the controller 40 according to the third embodiment of the present invention. The controller 40 of the present embodiment compares and determines the distance value with the meniscus 54 and 56 output from the eddy current sensors 10 and 30 with the standard value, and based on the determination result, the rotational speed of the motors 6 and 26 or the Danish 50 The pressurizing force of the pressurizing means 42 is controlled.

  The controller 40 of the present embodiment controls the pressure applied by the pressurizing means 42 of the Danish 50 when the measured value of the distance between the meniscus 54 and the meniscus 56 fluctuates out of the standard with the same tendency. That is, when both of the measured distance values are smaller than the minimum value of the standard, control is performed to reduce the pressurizing force of the pressurizing means 42, and the delivery amount of the molten metal 46 is reduced. When both measured values of the distance are larger than the maximum value of the standard, control to increase the pressurizing force of the pressurizing means 42 is performed to increase the delivery amount of the molten metal 46.

When the measured value of the distance of one of the meniscus 54 and the meniscus 56 deviates from the standard value and the other is within the standard, the controller 40 controls the rotational speed of the motor on the side deviating from the standard value. The rotational speed of the cooling rollers 2 and 22 is adjusted to suppress fluctuations in the meniscus position on the side deviating from the standard value.
Further, the controller 40, when the measured value of the distance of either the meniscus 54 or the meniscus 56 becomes a value smaller than the minimum value of the standard, and the other value becomes a value larger than the maximum value of the standard, By reducing the rotation speed of one motor and increasing the rotation speed of the other motor, the amount of the molten metal 46 taken in the cooling rollers 2 and 22 is adjusted, and the positions of the meniscuses 54 and 56 are both within the standard. Return to position.

(4th Example) FIG. 6: has shown typically arrangement | positioning of the molten metal and eddy current sensor which are supplied to the cooling roller of the metal sheet manufacturing apparatus concerning 4th Example of this invention.
In the metal sheet manufacturing apparatus of the present embodiment, a pair of cooling rollers 70 and 80 are arranged above and below with a constant gap. Four cooling water passages 72 a, 72 b, 72 c, 72 d are provided in parallel inside the upper cooling roller 70. The amount of cooling water in each cooling water passage is independently adjusted by the opening / closing amount of a cooling water valve (not shown). Four cooling water passages (not shown) are provided in parallel inside the lower cooling roller 80, and the amount of cooling water in each cooling water passage is independently adjusted by each cooling water valve.

  In the tundish 50 of this embodiment, eddy current sensors 60a, 60b, 60c, 60d are embedded above the slits 52. The embedded positions of the eddy current sensors 60a to 60d substantially coincide with the positions in the width direction of the cooling water passages 72a to 72d. Under the slit 52, four eddy current sensors (not shown) are embedded. The position of the lower eddy current sensor substantially coincides with the position of the cooling water passage of the lower cooling roller 80.

The controller 40 of the present embodiment compares and determines the output of each eddy current sensor with a standard value, and independently controls the opening / closing amount of the cooling water valve based on the determination result.
In FIG. 6, the meniscus portion 54 a that spreads around the outer periphery of the cooling roller 70 is too wide than the standard value. The controller 40 sequentially compares and determines the measurement values of all the eddy current sensors with the standard value, so that the values output from the eddy current sensors 60a and 60b that measure the distance 54a exceed the standard value. It is detected that the measured values of the eddy current sensors 60c and 60d that measure the distance of the remaining meniscus 54b are within the standard. In such a case, the controller 40 increases the opening amount of the cooling water valves of the cooling water passages 72a and 72b corresponding to the positions of the eddy current sensors 60a and 60b whose measured values of the distance are out of specification, and the cooling roller Increase the cooling capacity of 70. The meniscus 54a is prevented from spreading due to the increased cooling capacity of the cooling roller 70. Under the control of the controller 40, the meniscus 54a and 54b are both kept at a position within the standard.

  The metal sheet manufacturing apparatus of this embodiment independently controls a plurality of cooling water supply valves even when a part of the meniscus 54, 56 on the cooling rollers 70, 80 causes a position variation and exceeds a standard value. By doing so, the position of only the part that has changed can be returned to the position within the standard. It becomes possible to respond finely by the fluctuations of the meniscus 54, 56, and it is possible to produce a higher quality metal sheet.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. For example, in the embodiments, the configuration in which the arrangement of the pair of cooling rollers is vertically vertical has been described. However, the present technology also applies to an apparatus in which the cooling rollers are arranged horizontally and an apparatus arranged at an angle with respect to a horizontal plane. Is applicable. The combination in the case where the controller controls two or more operating conditions during operation is free, and the control flow by the controller can be freely changed within the range where the same effect can be obtained.

The figure which shows typically the structure of the manufacturing apparatus of the metal sheet of this invention. The flowchart which shows the control content of the controller of 1st Example. The figure which shows typically arrangement | positioning of the eddy current sensor of 1st Example. The flowchart which shows the control content of the controller of 2nd Example. The figure which shows the control content of the controller of 3rd Example. The figure which shows typically arrangement | positioning of the eddy current sensor of 4th Example, and a cooling water channel | path.

Explanation of symbols

2, 22, 70, 80 ... Cooling rollers 4, 24, 72 ... Cooling water passages 6, 26 ... Motors 8, 28 ... Cooling water valves 10, 30 ... Sensor coils 12, 32 ... AC power supply 14 34 .. Impedance meter 40. Controller 42. Pressurizing means 44. Heater 46. Metal melt 48. Metal sheet 50. Tundish 52. Slit 54, 56. Meniscus 60, 62. Vortex Current sensor

Claims (3)

An apparatus for producing a metal sheet from molten metal,
A pair of cooling rollers facing each other across a gap;
A dandy that feeds molten metal from the slit toward the gap,
An eddy current sensor that measures the distance to the meniscus where the molten metal delivered from the slit spreads toward a pair of cooling rollers;
A metal sheet manufacturing apparatus having a controller that increases or decreases at least one of the rotational speed of the cooling roller, the cooling capacity of the cooling roller, the temperature of the molten metal, and the delivery amount of the molten metal based on the output of the eddy current sensor . The rotational speed of the pair of cooling rollers can be controlled independently,
Eddy current sensors are provided on both sides of the slit,
Based on the output of the front eddy current sensor, the rotation speed of the front cooling roller is adjusted to increase or decrease,
2. The metal sheet manufacturing apparatus according to claim 1, wherein the rotation speed of the back side cooling roller is adjusted to increase or decrease based on the output of the back side eddy current sensor. It is a method for producing a metal sheet by sending molten metal from a slit to a gap between a pair of cooling rollers and cooling the molten metal fed into the gap with a cooling roller.
A step of measuring the distance to the meniscus using eddy current flowing in the meniscus where the molten metal delivered from the slit spreads toward the pair of cooling rollers;
Based on the measured distance, feedback control of the distance to the meniscus is made by adjusting at least one of the rotation speed of the cooling roller, the cooling capacity of the cooling roller, the temperature of the molten metal, and the delivery amount of the molten metal. The manufacturing method of the metal sheet which has a process to do.

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