JP2006169603A - Heating facility and heating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating facility and a heating method for metal strip with which the productivity can be improved by preventing the stop of an induction heating apparatus or a line-stop for a long period of time caused by breakage of the induction heating apparatus. <P>SOLUTION: In the heating facility arranged at a reheating zone inlet side or a reheating zone inner part in a continuous annealing process for metal strip, the heating facility is provided with the induction-heating apparatus and a heat-insulating material is arranged at least in a part of an induction heating coil surface faced to the passed-through metal strip in the induction heating apparatus. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a metal band heating facility and a heating method in a continuous annealing process of a metal band in which reheating treatment is performed for material adjustment after continuous annealing and rapid cooling.

  In the continuous annealing process of the metal strip, the mechanical properties of the metal strip to be processed vary greatly depending on the heat treatment conditions of heating and cooling. Therefore, control of the heat treatment conditions for heating and cooling is important. In particular, in recent years, the demand for high-tensile materials has increased, and the importance of rapid cooling technology advantageous for the production of high-tensile materials has increased. Rapid cooling methods include, for example, water quenching method, roll cooling method, air-water mixing (mist) cooling method, gas jet cooling method, etc., and the most suitable among these methods to obtain the necessary materials. A method is appropriately selected.

  Further, in the reheating zone performed after the rapid cooling, a method of applying an appropriate mechanical crown to the in-furnace roll is used so that the continuous feeding of the metal strip continuously conveyed is performed. However, a thermal crown occurs in the in-furnace roll due to the influence of the metal strip plate temperature and the ambient temperature around the in-furnace roll. The difference between the initial amount of mechanical crown of the in-furnace roll and the amount of thermal crown of the in-furnace roll during operation is within the appropriate range, and the plate is stable when the automatic centering function works effectively. To be done. However, when the difference in the crown amount becomes significantly large and deviates from the appropriate range, a compressive force in the width direction acts on the metal band, thereby causing the metal band to buckle in the width direction and causing a restriction, There is a risk that the plate will become unstable and operation will become impossible due to meandering.

As means for solving this problem, for example, in JP-A-2-274823 (Patent Document 1), an induction heating device is arranged as a rapid heating device between a cooling zone and a reheating zone, and the induction heating device is used. A technique is disclosed in which the temperature of the metal strip is controlled to adjust to an appropriate thermal crown amount so as to stabilize the threading plate.
JP-A-2-274823

  Since the technique described in Patent Document 1 uses an induction heating device having excellent temperature controllability and responsiveness, the amount of thermal crown is adjusted by appropriately controlling the temperature of the metal band passing through the induction heating device. This is an effective method for stabilizing the plate.

  However, in the continuous annealing process, since heating and cooling are repeated, a shape defect of the metal band is likely to occur. Such a defective shape of the metal band is particularly prominent in the metal band after water quenching.

  When the metal strip having such a defective shape enters the induction heating device, the metal strip frequently contacts the induction heating coil surface of the induction heating device. When the metal strip comes into contact with the induction heating coil surface, the induction heating device stops and the heating stops. Therefore, in order to secure a predetermined tempering temperature, the sheet feeding speed of the metal strip must be reduced, and the productivity is greatly reduced. . In addition, when the metal strip comes into contact with the surface of the induction heating coil that is energized in the induction heating device, melting of the induction heating coil due to sparks, etc. occurs. There is a problem that the cooling water passing through leaks into the heating furnace, causing a long-term facility shutdown.

  Note that the technique described in Patent Document 1 is incapable of dealing with such a problem.

  Accordingly, the present invention provides a metal band heating facility and heating method capable of improving productivity by preventing the induction heating device from being stopped or the line from being stopped for a long time due to the breakage of the induction heating device. The purpose is to provide.

In order to achieve the above object, the present invention has the following features.
[1] A heating facility provided on the reheating zone entry side or inside the reheating zone in the continuous annealing process of the metal strip,
The heating facility comprises an induction heating device;
A heating facility characterized in that an insulator is disposed on at least a part of the induction heating coil surface facing the metal band through which the induction heating device passes.
[2] In the above [1], comprising a roll for restraining the metal strip on the entry side and the exit side of the induction heating device,
A heating facility characterized in that an insulator is disposed at an intermediate position of a roll for binding the metal strip and in the vicinity thereof.
[3] A heating facility according to the above [1] or [2], wherein the insulator is an alumina-based ceramic.
[4] A method for heating a metal strip, comprising heating the cooled metal strip using the heating facility according to any one of [1] to [3].

  ADVANTAGE OF THE INVENTION According to this invention, the heating equipment and heating method of a metal strip which can aim at the improvement of productivity by preventing the stop of an induction heating apparatus or the long-time line stop accompanying the failure | damage of an induction heating apparatus Is provided.

  Hereinafter, an example of the best mode for carrying out the present invention will be described.

  FIG. 1 is a schematic view showing an example of the equipment configuration on the reheating zone entry side in the continuous annealing process of the metal strip provided with the heating equipment 10 according to the present invention.

  In FIG. 1, for example, after the metal band 2 that has passed through the rapid cooling zone 3 such as water quenching is wound around the transport roll 4 a and turned 90 degrees, after passing through the guide roll 5 a for restraining the metal band 2. The induction heating device 1 is introduced. The metal strip 2 heated to a predetermined temperature by the induction heating device 1 is unloaded from the induction heating device 1, passes through a guide roll 5b for restraining the metal strip 2, and then wraps around the transport roll 4b and rotates 90 degrees. It is converted and introduced into the reheating zone 6 of the next process.

  Here, according to the present invention, in the induction heating apparatus 1 constituting the heating facility, an insulator is disposed on at least a part of the induction heating coil surface facing the metal band 2 passing through the induction heating apparatus 1. .

  Here, alumina ceramics can be used as the insulator. Alumina-based ceramics are preferably used in the present invention because they are excellent in heat resistance and wear resistance.

  In addition, the insulator formed in a plate shape may be attached to the induction heating coil surface of the induction heating apparatus 1, or a method of performing thermal spraying or the like may be used.

  The insulator may be arranged on the entire surface of the induction heating coil surface of the induction heating apparatus 1, but it is preferable to arrange the insulator only in a part of the range where the metal strip 2 may come into contact. This is to reduce equipment costs.

  Here, as a range in which the metal band 2 on the induction heating coil surface of the induction heating apparatus 1 may come into contact, the metal band 2 provided in the immediate vicinity of the entrance side of the induction heating apparatus 1 is restrained. An intermediate position between the guide roll 5a and the guide roll 5b for constraining the metal strip 2 provided in the immediate vicinity of the exit side of the induction heating apparatus 1 and its vicinity are conceivable. This is because the vicinity of the intermediate position is considered to be the position where the vibration width becomes the largest when the metal strip 3 vibrates in the direction orthogonal to the traveling direction. The intermediate position and the vicinity thereof refer to a minimum range effective for preventing contact between the metal band and the induction heating coil surface from the intermediate position and the intermediate position toward the entry side and the exit side of the metal band, For example, it may be within about ± 20% of the length of the coil surface of the induction heating coil from the intermediate position.

  In addition, when the said intermediate | middle position remove | deviates from the induction heating apparatus 1, it is preferable to provide in the coil surface edge vicinity near the said intermediate position.

  Further, as a range in which the metal band 2 may come into contact, a portion through which the width direction end portion or the width direction center portion of the metal band 2 passes can be considered. This is because, when a shape defect occurs in a metal band after water quenching, the metal band 2 generally has a shape curved in an arc shape in the width direction.

  FIG. 2 shows an example of a preferable range when the insulator 1a is arranged on a part of the coil surface of the induction heating device 1. FIG. 2 is a front view of the coil surface viewed from the metal band 2 side. Further, the range of the area A shown in FIG. 2 represents an intermediate position between the guide roll 5a and the guide roll 5b and an area in the vicinity thereof.

  In the above embodiment, as shown in FIG. 1, the heating equipment 10 according to the present invention restrains the induction heating device 1 and the metal bands provided in the immediate vicinity of the entrance side and the exit side of the induction heating device 1. It is comprised by the guide rolls 5a and 5b for doing. However, in the present invention, it is not an essential requirement to provide the guide rolls 5a and 5b. However, in the case where the guide roll is not provided, it is preferable that an insulator is disposed at least on the end portion of the induction heating device 1 on the entry side and / or exit side, and is disposed on the entire surface of the induction heating coil. It is more preferable.

  In the absence of the guide rolls 5a and 5b, when a shape defect occurs in the metal band 2 passed through the induction heating device 1, the metal band 2 and the inner surface of the induction heating device 1 are in contact with each other. There is a case. However, even in this case, since an insulator is disposed on the coil surface of the induction heating apparatus 1, the occurrence of sparks due to contact can be prevented. As a result, it is possible to prevent the induction heating device 1 from being stopped due to the occurrence of a spark or a long-time line stop due to the breakage of the induction heating device 1, and further to improve productivity without having to reduce the plate passing speed. It becomes possible.

  On the other hand, when the guide rolls 5a and 5b or one of them is installed, the shape defect of the metal strip 2 passed through the induction heating device 1 is corrected. This has the effect of greatly reducing contact with the inner surface of the induction heating device 1. Thereby, the abrasion of the said insulator accompanying the contact with the metal strip 2 and an insulator can be reduced, and it becomes possible to reduce significantly the maintenance frequency, such as replacement | exchange of an insulator.

  As described above, in FIG. 1, the case where the induction heating device 1 is arranged vertically has been described, but the present invention can be similarly applied to the case where it is arranged horizontally. In this case, an insulator may be disposed only on the coil surface located below the induction heating device. This is because there is little possibility that the metal band contacts the upper side.

  In the above description, as shown in FIG. 1, the case where the induction heating device 1 is provided immediately before the reheating zone 6 on the reheating zone entrance side, that is, on the downstream side of the cooling zone 3 has been described. The apparatus 1 may be provided inside the reheating zone 6. However, in that case, it is preferable to provide in the first pass on the upstream side in the reheating zone 6 in the initial stage of temperature rise inside the reheating zone 6.

  In the continuous annealing facility shown in FIG. 1, the efficiency and insulation when continuous annealing is performed using an induction heating device in which an insulator is provided on the coil surface without the installation of guide rolls 5 a and 5 b (Invention Example 1). The efficiency was compared when continuous annealing was performed using an induction heating apparatus in which no object was arranged (comparative example). Here, the said efficiency was evaluated by the average of the processing amount (ton) of the metal strip per hour.

  As a result, in the comparative example, the induction heating device 1 was stopped at a rate of once per 660 tons of the charged metal band, whereas in the inventive example 1, the induction heating device 1 was not stopped. Further, the efficiency (average efficiency) of the comparative example was 44 tons / hour, whereas the efficiency (average efficiency) of the present invention example 1 was 48 tons / hour, and an insulator was provided on the coil surface of the present invention example. In the case where continuous annealing was performed using an induction heating apparatus provided with an improvement in production efficiency of about 10% was confirmed.

  Furthermore, in the case where guide rolls 5a and 5b for restraining the metal strip are provided on the entry side and the exit side of the induction heating device, when continuous annealing is performed using an induction heating device in which an insulator is disposed on the coil surface The efficiency of (Invention Example 2) was evaluated.

  As a result, the average processing amount (ton) of the metal strip per hour was the same as in the case of the above-described Example 1 of the present invention. However, in the case of the present invention example 2, since the contact between the metal strip and the inner surface of the induction heating device can be greatly reduced, the wear of the insulator disposed on the coil surface is the case of the above invention example 1 It was possible to reduce significantly compared to

  As a result of evaluating the difference in the amount of wear of the insulator in the case of the present invention example 2 and the present invention example 1, in the case of the present invention example 1, it is necessary to carry out the replacement work of the insulator once a year. On the other hand, in the case of the present invention example 2, it is sufficient to replace the insulator once every five years, and the further effect of the present invention example 2 was confirmed.

It is the schematic which shows an example of the equipment structure in the reheating zone entrance side in the continuous annealing process of the metal strip provided with the heating equipment concerning this invention. It is a figure which shows an example of the preferable range in the case of arrange | positioning an insulator to a part of coil surface of the induction heating apparatus concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Induction heating apparatus 1a Insulator 2 Metal strip 3 Rapid cooling zone 4a, 4b Transport roll 5a, 5b Guide roll 6 Reheating zone 10 Heating equipment

Claims (4)

Heating equipment provided on the reheating zone entry side or inside the reheating zone in the continuous annealing process of the metal strip,
The heating facility comprises an induction heating device;
A heating facility characterized in that an insulator is disposed on at least a part of the induction heating coil surface facing the metal band through which the induction heating device passes. Provided with a roll for restraining the metal strip on the entry side and the exit side of the induction heating device,
The heating equipment according to claim 1, wherein an insulator is disposed at an intermediate position of the roll for constraining the metal strip and in the vicinity thereof.   The heating equipment according to claim 1 or 2, wherein the insulator is alumina ceramics.   A method for heating a metal strip, comprising heating the metal strip after cooling using the heating facility according to any one of claims 1 to 3.

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