JP5598313B2 - Alloying control method and alloying control device - Google Patents

Description

  The present invention relates to an alloying control method and an alloying control apparatus.

  An alloyed hot-dip galvanized steel sheet having strength, malleability, ductility and corrosion resistance at the same time is widely used in automobiles and the like. In recent years, in addition to these performances, strength and thickness have been reduced in order to achieve both weight reduction for cost reduction, and the plating phase itself is required to have a thin and uniform property.

  In recent alloying hot dip galvanizing, an alloy layer having a thickness of about several μm has the above-mentioned properties, so that as many desired phases (δ phase) as possible are formed, and undesirable phases (for example, Γ phase, (Γ1 phase, ζ phase, etc.) are required to be as small as possible.

  The alloy layer to be generated is basically controlled by the conditions of the zinc bath and the heating conditions of the alloying furnace, but when a subtle change such as a change in bath temperature occurs, the change in the alloy layer accompanying such change is changed. There is a problem that there are few good methods for determining in a short time.

  As a method for judging such a change, there is a method of making a judgment by measuring a plated steel sheet by X-rays when it is cooled to room temperature in the latter stage of the alloying furnace, but at that time, an overalloy or an unalloyed alloy is found. If a lot of loss material has already occurred in such a case, an undesirable phase is as thin as 1 μm or less, or an alloy phase that does not exist on the surface, such as a Γ phase, has occurred. There were drawbacks such as that measurement errors were likely to occur.

  In addition, there is an empirical method such as judging the degree of alloying by visually observing the steel plate immediately after alloying, but it is a method that relies on personal judgment and evaluation, and it is only possible to make a determination based on surface information In addition, the alloy phase such as the Γ phase that is not present on the surface cannot be judged.

  In order to cope with such a problem, the following Patent Document 1 focuses on the fact that the emissivity change of the plating layer surface occurs depending on the progress of alloying, and determines the alloying by the emissivity change of the plating layer surface. A method of performing is disclosed. Moreover, in the following Patent Document 2, the emissivity is obtained from the radiant energy at a plurality of positions, and the position corresponding to the range where the emissivity is 0.4 to 0.7 is defined as the alloying position. A method of controlling to do so is disclosed. In Patent Document 3 below, the plate temperature in the plate traveling direction is measured at three or more locations, the temperature difference between adjacent plate temperatures is evaluated to determine the alloying position, and the plate temperature is determined based on the alloying position. A method of controlling is disclosed.

JP-A-57-185966 JP-A-7-150328 JP-A-4-218654

  Here, the methods disclosed in Patent Document 1 and Patent Document 2 are methods for calculating emissivity and assuming that the absolute value of radiant energy is reliable and used for control. On the other hand, the absolute value of radiant energy needs to be corrected by taking into account all differences in plate type and steel plate temperature, steel plate temperature fluctuation error, calculation error due to furnace wall temperature fluctuation, error due to plate speed difference, etc. In the said patent document 1 and the patent document 2, this point is not mentioned.

  The emissivity is a value that depends on the wavelength and the object temperature, but it is well known that in actual measurement, it is affected by surface contamination, oxidation state, roughness of the plate surface, and the like. Although the state of contamination on the surface of the steel sheet can be controlled to some extent by the cleaning process, it is difficult to actively control the oxidation state, roughness, etc. when priority is given to optimal alloying, resulting in a difference in the measured emissivity. is the current situation. Therefore, when it is assumed that the plate type and the temperature of the alloying furnace accompanying the plate type change frequently, management of the absolute value of the radiant energy is complicated and not effective.

  Moreover, in the said patent document 3, it is a technique which evaluates alloying by the difference of relative radiation thermometer measurement temperature, measures the temperature measured value of a radiation plate thermometer, and the temperature difference of an adjacent plate thermometer When the temperature is equal to or lower than the average reference temperature, one of the plate thermometer positions is set as the alloying completion position, and the temperature is set as the set value of the control plate thermometer. If the control thermometer and the measurement thermometer are different and there is a temperature difference, control may diverge. Basically, the control thermometer and the measurement plate Should be consistent with a thermometer. In addition, there is no problem if the plate thermometer used for the initial control and the plate thermometer at the alloying completion position (that is, the position to be used as a reference) match, but in other cases Since the temperature at each measurement point is basically different, control may be diverged. Furthermore, there is no mention of items that the radiometer is basically affected, such as differences due to the thickness of the main plate, furnace wall temperature, etc., and a method applicable when a certain plate type is used under certain conditions. It is.

  Then, this invention is made | formed in view of the said problem, The place made into the objective of this invention is following the fluctuation | variation of the operation which manufactures an alloyed hot dip galvanized steel plate, and the coating layer provided on the steel plate It is an object of the present invention to provide an alloying control method and an alloying control apparatus capable of stably controlling alloying of the alloy.

In order to solve the above-mentioned problem, according to a certain aspect of the present invention, for a steel sheet conveyed through a hot dip galvanizing line, the emissivity in the first half of the hot dip in the hot dip galvanizing line is measured along the steel sheet conveying direction. An emissivity measurement step for measuring at at least four measurement positions as S1, S2, S3, S4... In order from the side close to the alloying furnace provided in the previous stage of the retentive zone ;
Based on the measurement result of the emissivity, a difference calculating step for calculating the difference of the emissivity between measurement positions adjacent to each other, and whether the calculated difference of the emissivity is equal to or greater than a predetermined threshold value. An alloying determination step for determining whether the plating layer provided on the steel sheet is alloyed based on the above, and specifying the alloying region where the plating layer is alloyed in the tropical region, and the specified alloying region And an alloying furnace control step for controlling the output of the alloying furnace provided in the preceding stage of the retentive zone so that the plating layer is alloyed between the measurement position S2 and the measurement position S3 according to the position of The measurement position S2 is set inside the retentive zone, and the measurement position S3 is calculated based on the position of the measurement position S2, the emissivity change pattern of the steel plate, and the conveyance speed of the steel plate. Done Is set to, in the emissivity measurement step, the measurement results and L radiance with a radiation thermometer at each of the measurement positions, and the steel sheet temperature T _p which is calculated on the basis of the temperature drop pattern of the steel sheet, the coercive tropical Based on the wall surface temperature _Tw , the emissivity is calculated by the following formulas 1 to 3, and in the alloying furnace control step, the alloying region is positioned before the measurement position S2 to the measurement position S3. An alloy that reduces the output of the alloying furnace when positioned, and increases the output of the alloying furnace when the alloying region is located at a later stage than between the measurement position S2 and the measurement position S3. A control method is provided.

ここで、上記式１〜式３において、
ｚ：測定位置
ε：放射率
Ｌ：放射温度計による放射輝度の測定結果
Ｌ _ｐ ：鋼板からの自発光による放射輝度
Ｌ _ｗ ：保熱帯の内壁からの熱放射に起因する放射輝度
Ｔ _ｐ ：鋼板温度
Ｔ _ｗ ：保熱帯の壁面温度
ｃ _１ 、ｃ _２ ：定数
λ：放射温度計の観察波長
である。

Here, in the above formulas 1 to 3,
z: Measurement position
ε: Emissivity
L: Measurement result of radiance by radiation thermometer
L _p : Radiance due to self-emission from steel plate
L _w : Radiance due to thermal radiation from the inner wall of the tropical zone
T _p : steel plate temperature
T _w : Wall temperature in the tropical zone
c ₁ , c ₂ : constant
λ: Observation wavelength of radiation thermometer
It is.

In the alloying determining step, before Symbol refers to database described for each type of steel sheet, wherein the data including the difference in the emissivity of the steel sheet, it is preferable that the plating layer is to determine alloyed.

  The measurement positions of the emissivity after the fifth place are preferably set between the measurement position S1 and the measurement position S2, or between the measurement position S3 and the measurement position S4.

  The furnace temperature set value or output of the alloying furnace may be varied at predetermined time intervals.

In order to solve the above-mentioned problems, according to another aspect of the present invention, for a steel sheet transported through a hot dip galvanizing line, the emissivity in the first half of the hot dip in the hot dip galvanizing line is calculated as the same location of the steel sheet. for the emissivity measuring step of measuring over a predetermined section in the first half of the coercive tropical on the basis of the measurement of the emissivity result, the emissivity between the measurement end position and the measurement start position of the emissivity A difference calculating step for calculating a difference, and an alloy for determining whether the plating layer provided on the steel sheet is alloyed by comparing the measured emissivity and the calculated emissivity difference with a predetermined threshold. In accordance with the alloying determination step and the alloying determination result, the output of the alloying furnace provided in the preceding stage of the retentive zone is controlled so that the plating layer is alloyed within the predetermined section. That alloyed furnace controlling step comprises, in the emissivity measurement step, the measurement results and L radiance with a radiation thermometer at each of the measurement positions, the steel sheet temperature is calculated based on the temperature drop pattern of the steel sheet T and _p, and the wall temperature T _w of the coercive tropical based on, is the emissivity calculated by the formula 1 formula 3, in the alloying furnace control step, emissivity at the measurement start position is first An alloying control method for reducing the output of the alloying furnace when the threshold is exceeded, and increasing the output of the alloying furnace when the emissivity at the measurement end position is less than a second threshold. Is provided.

  In the alloying furnace control step, when the emissivity difference increases with time, it is preferable to reduce the output of the alloying furnace.

  In the alloying determination step, it is determined whether or not the plating layer is alloyed by referring to a database in which the steel plate characteristic data including the first threshold value and the second threshold value is described for each type of steel plate. Is preferred.

In order to solve the above problems, according to still another aspect of the present invention, for a steel sheet transported through a hot dip galvanizing line, the emissivity in the first half portion of the hot dip in the hot dip galvanizing line is measured in the steel sheet transport direction. An emissivity calculation unit that calculates at least four measurement positions in the order of S1, S2, S3, S4... From the side close to the alloying furnace provided in the preceding stage of the retentive zone,
Based on the measurement result of the emissivity, an emissivity difference calculation unit that calculates the emissivity difference between the measurement positions adjacent to each other, and whether the calculated emissivity difference is equal to or greater than a predetermined threshold value It is determined whether the plating layer provided on the steel sheet is alloyed based on whether or not , the alloying position specifying part for specifying the alloying region where the plating layer is alloyed in the tropical region, and the specified An alloying furnace control unit for controlling the output of the alloying furnace provided in the preceding stage of the retentive zone so that the plating layer is alloyed between the measurement position S2 and the measurement position S3 according to the position of the alloying region; The measurement position S2 is set inside the retentive zone, and the measurement position S3 includes the position of the measurement position S2, the emissivity change pattern of the steel plate, and the conveyance speed of the steel plate. Set to a position calculated based on Is the emissivity calculating unit, the measurement result and L radiance with a radiation thermometer at each of the measurement positions, and the steel sheet temperature T _p which is calculated on the basis of the temperature drop pattern of the steel sheet, the wall temperature of the coercive tropical and T _w, based on, by the formula 1 formula 3 calculates the emissivity, the alloying furnace control unit, when the alloyed region is positioned upstream than between said predetermined measurement position An alloying control device is provided that reduces the output of the alloying furnace and increases the output of the alloying furnace when the alloying region is located at a later stage than between the predetermined measurement positions.

In order to solve the above problems, according to still another aspect of the present invention, the steel sheet transported through the hot dip galvanizing line has the same emissivity as that of the steel sheet in the first half of the hot dip in the hot dip galvanizing line. An emissivity calculation unit that calculates a predetermined section in the first half of the retentive zone with respect to the location, and the emissivity between the emissivity measurement start position and the measurement end position based on the emissivity measurement result An emissivity difference calculation unit for calculating the difference between the measured emissivity and the calculated emissivity difference is compared with a predetermined threshold value to determine whether the plating layer provided on the steel sheet has been alloyed. An alloying determination unit for determining and an output of an alloying furnace provided in the preceding stage of the retentive zone so that the plating layer is alloyed within the predetermined section according to the determination result of the alloying. alloy Comprising a furnace controller, wherein the emissivity calculating unit, the measurement result and L radiance with a radiation thermometer at each of the measurement positions, and the steel sheet temperature T _p which is calculated on the basis of the temperature drop pattern of the steel sheet, and wall surface temperature T _w of the coercive tropical based on, calculates the emissivity according to equation 1 to equation 3, the alloying furnace control unit, the measurement start emissivity exceeds a first threshold value at the position Is provided, an alloying control device is provided that reduces the output of the alloying furnace and increases the output of the alloying furnace when the emissivity at the measurement end position is less than a second threshold. The

  As described above, according to the present invention, the alloying state of the plating layer is determined based on the measured emissivity and the difference in emissivity, and the output of the heating furnace is controlled according to the determination result. It is possible to follow the fluctuations in the operation for producing the hot dip galvanized steel sheet and to stably control the alloying of the plated layer.

It is explanatory drawing which showed the outline of the hot dip galvanizing line which concerns on the 1st Embodiment of this invention. It is the block diagram which showed the structure of the alloying control apparatus which concerns on the same embodiment. It is explanatory drawing for demonstrating the measuring method of the emissivity which concerns on the same embodiment. It is explanatory drawing for demonstrating the determination method of alloying which concerns on the embodiment. It is explanatory drawing for demonstrating the determination method of alloying which concerns on the embodiment. It is explanatory drawing for demonstrating the determination method of alloying which concerns on the embodiment. It is explanatory drawing which showed an example of the alloying related database which concerns on the same embodiment. It is the flowchart which showed an example of the flow of the alloying control method which concerns on the same embodiment. It is explanatory drawing which showed the outline of the hot dip galvanizing line which concerns on the 2nd Embodiment of this invention. It is explanatory drawing for demonstrating the measuring method of the emissivity which concerns on the same embodiment. It is the block diagram which showed the structure of the alloying control apparatus which concerns on the same embodiment. It is explanatory drawing for demonstrating the determination method of alloying which concerns on the embodiment. It is the flowchart which showed an example of the flow of the alloying control method which concerns on the same embodiment. It is the block diagram which showed the hardware constitutions of the alloying control apparatus which concerns on embodiment of this invention. It is explanatory drawing for demonstrating 1st Example of this invention. It is explanatory drawing for demonstrating 2nd Example of this invention.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

(First embodiment)
<About hot dip galvanizing line>
First, an outline of a hot dip galvanizing line according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is an explanatory view showing an outline of a hot dip galvanizing line according to the present embodiment.

  As shown in FIG. 1, the steel sheet S conveyed from the annealing furnace is immersed in a zinc bath 10 containing molten zinc and various additives. The direction of the steel sheet S is changed by the sink roll 11 installed in the zinc bath 10 and conveyed in a substantially vertical direction.

  The steel sheet S coming out of the zinc bath 10 has a hot dip galvanized layer (hereinafter also simply referred to as a plated layer) formed on the surface thereof. The steel plate S with the plating layer formed on the surface is conveyed to the alloying furnace 20 such as an induction heater and heated to a predetermined steel plate temperature. The steel sheet S exiting the alloying furnace 20 (the steel sheet S with a plating layer formed on the surface) is subsequently transported to the retentive zone 30.

  In the steel sheet S formed on the surface of the plating layer, the plating layer is alloyed at any position within the tropical zone 30. The steel sheet S exiting the retentive zone 30 is cooled in the cooling zone 40 and cooled to near normal temperature.

  Here, the zinc bath 10 is controlled to a substantially constant temperature (for example, about 450 ° C.). In the zinc bath 10, the temperature of the steel sheet S is substantially the temperature of the zinc bath 10. Although the temperature of the steel sheet S exiting the zinc bath 10 decreases before it enters the alloying furnace 20, the steel sheet temperature rises by being carried into the alloying furnace 20 using an induction heater or the like. To go. As a result, the temperature of the steel sheet rises to about 520 ° C. at the time of leaving the alloying furnace 20 and entering the retentive zone 30.

  Here, in the hot dip galvanizing process which has been introduced in recent years, it has become clear that the steel plate temperature is not constant in the retentive zone 30 and the steel plate temperature is gradually decreasing. The steel sheet with the plating layer formed on the surface is alloyed at a certain place in the retentive zone 30 while the temperature gradually decreases in the retentive zone 30. The alloyed plated steel sheet is carried into the cooling zone 40 when it leaves the retentive zone 30 and is further cooled to near normal temperature.

  Further, in the hot dip galvanizing line 1, by providing a device (not shown) for blowing high temperature gas into the retentive zone 30, it becomes possible to keep the temperature inside the retentive zone 30 high. As a result, it is possible to produce a steel type that is required to maintain a high temperature in the retentive zone 30 and advance alloying.

  Here, in the hot dip galvanizing line 1 according to the present embodiment, in order to specify the spectral emissivity (hereinafter, also simply referred to as emissivity) of the steel sheet S on which the plated layer is formed, At least four alloying sensors 50 are installed. These alloying sensors 50 are an example of an emissivity measuring apparatus. The alloying sensor 50 may be any sensor that can measure the emissivity or the physical quantity used for calculating the emissivity of the steel sheet conveyed through the hot dip galvanizing line 1. As an example of the physical quantity used for calculating the emissivity of the steel plate, the temperature (radiation temperature) of the steel plate, radiance, and the like can be given. Further, as an aid for specifying the emissivity of the steel sheet S, a thermometer (not shown) that can measure the wall temperature of the tropical zone 30 such as a thermocouple, for example, with respect to the wall surface of the tropical zone 30 and the like. It may be provided.

  The vicinity of the retentive zone 30 refers to an area composed of the retentive zone 30 of the hot dip galvanizing line 1 and the area between the alloying furnace 20 and the retentive zone 30. In addition, the alloying sensor 50 at the position closest to the zinc bath 10 among the at least four radiation thermometers 50 may be installed in the alloying furnace 20 instead of in the vicinity of the retentive zone 30.

  Measurement results from at least four alloying sensors 50 and the like are output to the alloying control device 100 according to the present embodiment. The alloying control device 100 uses the measurement result output from the alloying sensor 50 to calculate the emissivity of the plating layer formed on the steel sheet S transported through the hot dip galvanizing line 1, and the alloy of the plating layer The degree of conversion is determined. Moreover, the alloying control apparatus 100 controls alloying of a plating layer according to the determination result of the degree of alloying. Specifically, the alloying control apparatus 100 outputs a control signal or the like to various alloying furnace control means 60 capable of controlling the alloying furnace 20 to control the alloying furnace 20. .

  The alloying control device 100 will be described in detail below again.

<Change in emissivity with the progress of alloying>
Next, a change in emissivity with the progress of alloying will be briefly described.
It is known that when the zinc on the plating surface is alloyed with the base iron, an abrupt emissivity (or reflectivity) change occurs. The steel plate surface immediately after plating is specular and has a low emissivity. However, in the process where iron diffuses into the zinc layer due to alloying, the surface roughness of the steel sheet increases rapidly, and as a result, the emissivity increases. For example, although the emissivity immediately after plating is about 0.2, although it varies depending on the steel type, it is known that the emissivity increases to 0.6 to 0.8 by alloying. Therefore, by paying attention to the change in emissivity measured by the alloying sensor, it can be determined whether or not the alloying of the plating layer is completed.

<About the structure of the alloying control device>
Next, the configuration of the alloying control apparatus 100 according to the present embodiment will be described in detail with reference to FIG. FIG. 2 is a block diagram showing the configuration of the alloying control apparatus according to the present embodiment.

  In the following description, the alloying control device 100 described below calculates the emissivity of the steel sheet S using the measurement result output from the alloying sensor 50 provided in the hot dip galvanizing line 1. However, the present invention is not limited to such an example. That is, if the alloying sensor 50 provided in the hot dip galvanizing line 1 can directly output the emissivity of the steel sheet S, the emissivity itself output by the alloying sensor 50 is used to It is also possible to carry out the processing as described in.

  As shown in FIG. 2, the alloying control apparatus 100 according to the present embodiment includes a steel plate measurement information acquisition control unit 101, an emissivity calculation unit 103, an emissivity difference calculation unit 105, and an alloying position specifying unit 107. And an alloying furnace control unit 109, a display control unit 111, and a storage unit 113.

  The steel plate measurement information acquisition control unit 101 is realized by, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a communication device, and the like. The steel plate measurement information acquisition control unit 101 performs control to acquire steel plate measurement information related to the measurement result of the steel plate output from the alloying sensor 50 installed in the vicinity of the tropical rain reservoir 30. In addition, when a wall surface thermometer for measuring the wall temperature of the retentive zone 30 is installed in the vicinity of the retentive zone 30, the steel plate measurement information acquisition control unit 101 outputs output from the wall surface thermometer. Also get data.

  Here, in the hot dip galvanizing line 1 according to the present embodiment, as shown in FIG. 3, at least four alloying sensors 50 are installed in order to measure the emissivity of at least four places. These alloying sensors 50 are preferably installed in the first half portion of the retentive zone 30, as shown in FIG.

  As shown in FIG. 3, the installation positions of these at least four alloying sensors 50 (that is, emissivity measurement positions) are S1, S2, S3, S4... In order from the side closer to the alloying furnace 20. As shown in FIG. 3, the alloying sensor 50 corresponding to the measurement position S1 may be provided on the entry side of the retentive zone 30, and between the alloying furnace 20 and the retentive location 30. It may be installed, and may be provided inside the alloying furnace 20 or on the outlet side of the alloying furnace 20. Moreover, it is preferable to provide the alloying sensor 50 corresponding to the measurement position S2 inside the retentive zone 30 as shown in FIG.

  Further, as shown in FIG. 3, the alloying sensor 50 corresponding to the measurement position S3 is provided inside the retentive zone 30, but the installation position of the alloying sensor 50 corresponding to the measurement position S3 is It is determined according to the position of the alloying sensor 50 corresponding to the measurement position S2.

  That is, in the alloying control apparatus 100 according to the present embodiment, as will be described below, the plating layer formed on the steel sheet S is alloyed in the region between the measurement position S2 and the measurement position S3 (region A2 in FIG. 3). The setting and output of the alloying furnace 20 are controlled so that Therefore, the installation position of the alloying sensor 50 corresponding to the measurement position S3 is important in performing appropriate alloying control. Alloying of the plating layer formed on the steel sheet S proceeds as iron atoms of the steel sheet S as a base material diffuse into the plating layer. Therefore, in the hot dip galvanizing line 1 according to the present embodiment, the alloying speed and emissivity at which the plating layer is alloyed based on various information such as past operation record data, laboratory experimental results, literature descriptions, and the like. The speed information such as the change speed is specified in advance. Since the alloying rate in the plating thickness direction is considered to be almost constant for steel plates of the same steel type, the change pattern of emissivity on the plating surface in time units is almost constant for the same steel plate, and the same transmission rate. Since the change in emissivity at the plate speed is considered to change the position in the longitudinal direction depending on the degree of alloying, in the hot dip galvanizing line 1 according to the present embodiment, based on the speed information and the conveyance speed of the steel plate S. Thus, the position of the measurement position S3 is determined. For example, as shown in FIG. 4A, which will be described later, the measurement position S3 and the installation interval of the alloying sensor 50 are determined so that the portion where the change in emissivity is large is located between the measurement position S2 and the measurement position S3. .

  Specifically, when operating at a constant speed, a large number of holes are made in the wall of the retentive zone 30, the inside (radiation chamber) is measured from each hole, and a rapid change pattern of emissivity is obtained. The position where the emissivity starts to change and the position where the emissivity changes gradually are specified in advance, and the measurement position S2 and the measurement position S3 are determined from the positions of the nearest holes before and after the position including the position. That's fine.

  In addition, in order to specify the position where the emissivity starts to change suddenly, it is only necessary to specify a part that is equal to or higher than a preset emissivity change rate. For example, a value such as 10% can be used as the emissivity change rate set in advance. Similarly, when specifying the position where the change in emissivity is moderate, it is only necessary to specify a portion that is equal to or less than a preset change rate of emissivity. For example, a value such as 10% can be used as a change in emissivity set in advance.

  Further, when alloying another steel type whose steady speed changes, the alloying sensor 50 is moved manually or automatically to a position specified in advance.

  Further, when the fifth and subsequent alloying sensors 50 are installed in the hot dip galvanizing line 1 according to the present embodiment, between the measurement position S1 and the measurement position S2, or between the measurement position S2 and the measurement position S3 (that is, 3 is preferably installed in the area A1 or the area A3) in FIG. As will be described below, in the alloying control apparatus 100 according to the present embodiment, the position where alloying of the plating layer occurs (also referred to as alloying position) is located in any one of the areas A1, A2, and A3. Accordingly, it is determined whether alloying of the plating layer is appropriate or whether a phenomenon such as overalloy or unalloy has occurred. Here, the case where the region A1 is an alloying position corresponds to overalloy, and the case where the region A3 is an alloying position corresponds to unalloyed. Therefore, when it is desired to determine in more detail whether or not an overalloy has occurred, it is only necessary to install the fifth and subsequent alloying sensors 50 in the region A1, and in more detail whether or not an unalloyed state has occurred. If it is desired to make a determination, the fifth and subsequent alloying sensors 50 may be installed in the area A3. Further, when it is desired to make a more detailed determination regarding overalloy and unalloy, an alloying sensor 50 may be further installed in both the region A1 and the region A3.

  In addition, the space | interval of the adjacent alloying sensor 50 may be equal intervals, and may differ for every place.

  The steel plate measurement information acquisition control unit 101 according to the present embodiment acquires the steel plate measurement information corresponding to the measurement result from each alloying sensor 50 installed in this manner, and acquires it in the emissivity calculation unit 103 described later. Outputs steel plate measurement information. Further, when the steel plate measurement information acquisition control unit 101 acquires the output data output from the wall surface thermometer for measuring the wall temperature of the tropical region 30, the output data is included in the steel plate measurement information and radiated. The result is output to the rate calculation unit 103.

  The steel plate measurement information acquisition control unit 101 may associate the acquired steel plate measurement information with time information related to the date and time when the information is acquired and store the information in the storage unit 113 as history information.

  The emissivity calculation unit 103 is realized by, for example, a CPU, a ROM, a RAM, and the like. The emissivity calculation unit 103 is based on the steel plate measurement information output from the steel plate measurement information acquisition control unit 101, and calculates the emissivity of the steel plate S conveyed through the hot dip galvanizing line 1 at the position where the alloying sensor 50 is installed. It calculates with each of. With this emissivity calculation process, the emissivity of the steel sheet S at each measurement position is measured. The emissivity calculation unit 103 can calculate the emissivity by appropriately using various calculation methods according to the content of the steel plate measurement information output from the steel plate measurement information acquisition control unit 101.

  When the emissivity calculating unit 103 calculates the emissivity of the steel sheet S at each measurement position, the emissivity calculating unit 103 outputs information on the calculated emissivity to the emissivity difference calculating unit 105 described later. The emissivity calculating unit 103 may output information on the calculated emissivity to the alloying position specifying unit 107 described later. In addition, the emissivity calculation unit 103 may output information on the calculated emissivity to the display control unit 111 described later, and display the calculation result on a display unit (not shown) such as a display. . The emissivity calculation unit 103 may associate the time information related to the date and time when the information is calculated with the information related to the calculated emissivity and store the information in the storage unit 113 as history information.

  The emissivity difference calculation unit 105 is realized by, for example, a CPU, a ROM, a RAM, and the like. The emissivity difference calculation unit 105 calculates an emissivity difference between measurement positions adjacent to each other based on information on the emissivity output from the emissivity calculation unit 103. For example, as shown in FIG. 3, it is assumed that four alloying sensors 50 are installed in the hot dip galvanizing line 1, and the emissivities at the measurement positions are ε1, ε2, ε3, and ε4, respectively. In such a case, the emissivity difference calculation unit 105 calculates three types of differences, ε2-ε1, ε3-ε2, and ε4-ε3.

  When the calculation of the emissivity difference is completed, the emissivity difference calculation unit 105 outputs the obtained calculation result to the alloying position specifying unit 107 described later. Further, the emissivity difference calculation unit 105 may output information on the calculated emissivity difference to the display control unit 111 and display the calculation result on a display unit (not shown) such as a display. . The emissivity difference calculation unit 105 may associate the time information related to the date and time when the information is calculated with the information related to the calculated emissivity difference and store the information in the storage unit 113 as history information.

  The alloying position specifying unit 107 is realized by a CPU, a ROM, a RAM, and the like, for example. The alloying position specifying unit 107 determines whether the plating layer formed on the steel sheet is alloyed based on the difference in emissivity calculated by the emissivity difference calculating unit 105, and the plating layer is alloyed in the tropical region. The position of the alloyed region (alloying position) is specified.

  As described above, when zinc existing on the surface of the galvanized layer is alloyed with the ground iron, an abrupt increase in emissivity occurs. Therefore, the alloying position specifying unit 107 determines that the plating layer is alloyed based on whether or not the difference in emissivity calculated by the emissivity difference calculating unit 105 is equal to or greater than a predetermined threshold set for each steel type. It can be determined whether or not.

  Below, it demonstrates concretely taking the case where the four alloying sensors 50 are installed in the hot dip galvanizing line 1 as an example, referring FIG. 4A-FIG. 4C.

  Here, as shown in FIG. 4A, when the difference in emissivity defined by ε3−ε2 is equal to or greater than a predetermined threshold value, the alloying position specifying unit 107 determines the region A2 (measurement shown in FIG. It is determined that alloying has occurred in the plating layer between position S2 and measurement position S3). Further, as described below, the alloying control apparatus 100 according to the present embodiment determines that appropriate alloying is in progress when alloying occurs in the region A2.

  Further, as shown in FIG. 4B, when the difference in emissivity defined by ε2−ε1 is equal to or larger than a predetermined threshold, the alloying position specifying unit 107 displays the region A1 (measurement position) shown in FIG. It is determined that alloying has occurred in the plating layer between S2 and measurement position S1). Further, as will be described below, in the alloying control apparatus 100 according to the present embodiment, when alloying occurs in the region A1, the plated steel sheet manufactured in the hot dip galvanizing line 1 is in an overalloyed state. to decide.

  Further, as shown in FIG. 4C, when the difference in emissivity defined by ε4−ε3 is equal to or greater than a predetermined threshold, the alloying position specifying unit 107 displays the region A3 (measurement position) shown in FIG. It is determined that alloying has occurred in the plating layer between S4 and measurement position S3). Further, as described below, in the alloying control device 100 according to the present embodiment, when alloying occurs in the region A3, the plated steel sheet manufactured in the hot dip galvanizing line 1 is in an unalloyed state. to decide.

  Here, the alloying position specifying unit 107 calculates a threshold used for determining whether or not alloying is performed by referring to an alloying-related database as shown in FIG. This alloying-related database is stored in the storage unit 113 and the like, and can be referred to by the alloying position specifying unit 107 as needed. In this alloying-related database, as shown in FIG. 5, for each steel type, the emissivity at the measurement position S2 and the measurement position S3 and the difference (S3-S2) when proper alloying occurs, A difference β (S4−S3) between the final emissivity value of the alloyed plating layer and the emissivity at the measurement position S3 is described.

  Note that the value of the difference β is a value between the time when the plating phase is almost stabilized and solidified (S3) until the iron slowly diffuses and finally the phase is fixed (S4), and is 0. It shows a value of about .1 to 0.2 and is almost constant depending on the steel sheet type. Therefore, regarding the alloying control in the present embodiment, the change in emissivity represented by (S3-S2) is used as an index as will be described later, but the alloying control accuracy is improved, especially overalloying is prevented. For example, the following control can be performed. That is, when the threshold value for the difference β is set to a predetermined value (for example, 0.1) and the difference (S3−S2) is equal to or greater than the threshold value, Controls such as an output reduction that is about half of the output reduction performed in S3-S2 are performed. Thereby, finer control becomes possible.

  Further, the alloying related database is not limited to the database format, and may be stored in the storage unit 113 or the like in a format such as a lookup table.

  In the above description, the case where the emissivity is sharply increased in any one of the regions A1 to A3 has been described. However, the determination of unalloyed or overalloyed can be performed in addition to the method described above. is there. That is, when a high emissivity that can be determined to be alloying is observed at the measurement position S1, it is determined that the plated steel sheet manufactured in the hot dip galvanizing line 1 is in an overalloyed state. Can do. Also, at the measurement position S4, if the emissivity that can be determined to be alloying is not observed, it is determined that the plated steel sheet manufactured by the hot dip galvanizing line 1 is in an unalloyed state. be able to.

  When the alloying position specifying unit 107 specifies the alloying position by the above-described method, the alloying position specifying unit 107 outputs information indicating the result of specifying the alloying position to the alloying furnace control unit 109. Further, the alloying position specifying unit 107 may output information regarding the specified alloying position to the display control unit 111 and display the specifying result on a display unit (not shown) such as a display. The alloying position specifying unit 107 may associate the time information related to the date and time when such information is generated with the information related to the specified alloying position and store the information in the storage unit 113 as history information.

  The alloying furnace control unit 109 is realized by, for example, a CPU, a ROM, a RAM, a communication device, and the like. The alloying furnace control unit 109 controls the alloying furnace so that the plating layer is alloyed in a predetermined region according to the position (alloying position) of the alloying region specified by the alloying position specifying unit 107. .

  In the present embodiment, attention is paid to the case where it is appropriate to alloy the plating layer formed on the steel sheet S in the region A2 (between the measurement position S2 and the measurement position S3). Therefore, the alloying furnace control unit 109 refers to the information on the alloying position specified by the alloying position specifying part 107, and controls the alloying furnace 20 when the alloying position is not the region A2. .

  Specifically, when the alloying position is located before the region A2, that is, when the alloying position is the region A1, the alloying furnace control unit 109 avoids being in an overalloy state. In order to cause alloying in the region A2, the output of the alloying furnace is reduced. Further, when the alloying position is located at a later stage than the area A2, that is, when the alloying position is the area A3, the alloying furnace control unit 109 avoids being in an unalloyed state, and the area A2 In order to allow alloying to occur, the power of the alloying furnace is increased.

  Here, the control for increasing or decreasing the output of the alloying furnace may be appropriately selected according to the type of the alloying furnace to be used. For example, the maximum temperature setting value TH of the alloying furnace is set. What is necessary is just to increase / decrease or to increase / decrease the output (for example, the amount of electric current etc. which flows into a heater) of the heating apparatus for heating an alloying furnace.

  Further, the degree of increase / decrease of the output of the alloying furnace may be appropriately selected according to the type of the alloying furnace used, the size of the equipment, the steel type, etc., for example, the maximum temperature setting value of the alloying furnace It is only necessary to increase / decrease TH by 5 ° C. or increase / decrease the amount of current flowing through the heater by 2.5%.

  When the alloying furnace control unit 109 selects a control method as described above according to the alloying position, the alloying furnace control unit 109 generates a control signal corresponding to the selected control method and outputs the control signal to the alloying furnace control means 60. The alloying furnace control means 60 controls the alloying furnace 20 based on the control signal output from the alloying furnace control unit 109. Thereby, the alloying furnace 20 is controlled so that the alloying position is in the region A2.

  The display control unit 111 is realized by, for example, a CPU, a ROM, a RAM, a communication device, and the like. The display control unit 111 displays information related to the alloying position transmitted from the alloying position specifying unit 107, such as a display unit provided in the alloying control device 100, or other information provided outside the alloying control device 100. Display control is performed when displaying on a display unit such as a display of the apparatus. In addition to the information on the alloying position, the display control unit 111 can cause the display unit to display various types of information such as calculated values such as emissivity and graphs showing transitions of these values. . The display control unit 111 causes the display unit to display the result of the alloying position on the display unit, so that the user of the alloying control apparatus 100 grasps the information about the alloying position of the steel sheet S being conveyed on the spot. It becomes possible.

  The memory | storage part 113 is an example of the memory | storage device with which the alloying control apparatus 100 which concerns on this embodiment is provided. The storage unit 113 stores a database used when the alloying position specifying unit 107 specifies the alloying position. Further, the storage unit 111 stores various databases and programs used when the emissivity calculation unit 103 calculates emissivity, information on the installation order and installation positions of the plurality of alloying sensors 50, and the like. Good. Further, in the storage unit 113, the alloying control apparatus 100 according to the present embodiment stores various parameters, the progress of the processing, etc. that need to be saved when performing some processing, or various databases, etc. Stored as appropriate. Each storage unit included in the alloying control device 100 can freely read from and write to the storage unit 113.

Heretofore, the alloying control apparatus 100 according to the present embodiment has been described in detail.
In addition, the alloying control apparatus 100 according to the present embodiment continuously measures the emissivity, and may continuously perform various determinations regarding alloying, or continuously measure the emissivity. In addition, various determinations regarding alloying may be performed intermittently at predetermined time intervals. Moreover, the alloying control apparatus 100 according to the present embodiment may intermittently perform various determinations regarding emissivity measurement and alloying at predetermined time intervals.

  Further, the alloying furnace control means 60 according to the present embodiment constantly changes the maximum temperature setting value of the alloying furnace and the output of the heating device for heating the alloying furnace every time interval of about 1 second. May be. In this case, the fluctuation range of the maximum temperature setting value of the alloying furnace is preferably about ± 2 ° C., and the fluctuation range of the output of the heating device is preferably about ± 1%. By varying the setting of the alloying furnace in this way, it is possible to improve the determination accuracy of the unalloyed state or the overalloyed state.

  Heretofore, an example of the function of the alloying control device 100 according to the present embodiment has been shown. Each component described above may be configured using a general-purpose member or circuit, or may be configured by hardware specialized for the function of each component. In addition, the CPU or the like may perform all functions of each component. Therefore, it is possible to appropriately change the configuration to be used according to the technical level at the time of carrying out the present embodiment.

  A computer program for realizing each function of the alloying control apparatus according to the present embodiment as described above can be produced and installed in a personal computer or the like. In addition, a computer-readable recording medium storing such a computer program can be provided. The recording medium is, for example, a magnetic disk, an optical disk, a magneto-optical disk, a flash memory, or the like. Further, the above computer program may be distributed via a network, for example, without using a recording medium.

<About the alloying control method>
Next, the flow of the alloying control method according to the present embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing an example of the flow of the alloying control method according to the present embodiment.

  First, at least four alloying sensors 50 provided in the vicinity of the hot dip galvanizing line 1 measure the emissivities of the steel sheets S at at least four locations (step S101) and output them to the alloying control device 100. Here, when the alloying sensor 50 is a sensor that measures a physical quantity that can be used for calculating the emissivity, not the emissivity of the steel sheet, as described above, the emissivity calculating unit of the alloying control apparatus 100. In step 103, the emissivity of the steel sheet may be calculated based on the information obtained as a result of the measurement.

  The emissivity difference calculation unit 105 of the alloying control apparatus 100 calculates an emissivity difference between adjacent measurement positions based on the measured emissivity of the steel sheet (step S103), and obtains the obtained calculation result. And output to the alloying position specifying unit 107.

  The alloying position specifying unit 107 specifies a position (alloying position) where the plating layer formed on the steel plate is alloyed based on the difference in emissivity calculated by the emissivity difference calculating unit 105 (step S105). The obtained specific result is output to the alloying furnace control unit 109.

  The alloying furnace control unit 109 refers to the result of specifying the alloying position in the alloying position specifying unit 107 and determines what control is to be performed (step S107). That is, when the alloying position is a desired region (for example, region A2 in FIG. 3), the alloying furnace control unit 109 changes the setting of the alloying furnace, assuming that appropriate alloying is in progress. do not do. In addition, the alloying furnace control unit 109 avoids the overalloy state when the alloying position is in the preceding stage of the desired region (for example, the region A1 in FIG. 3) so that alloying occurs in the desired region. Next, control for reducing the output of the alloying furnace is performed (step S109). Also, the alloying furnace control unit 109 avoids the unalloyed state and causes alloying to occur in the desired region when the alloying position is in the subsequent stage of the desired region (for example, the region A3 in FIG. 3). Next, control for increasing the output of the alloying furnace is performed (step S111).

  After performing such control, the alloying furnace control unit 109 determines whether to end the control of the alloying furnace (step S113). If the user or the like of the alloying control device 100 has not performed an operation to end the control, the alloying control device 100 returns to step S101 and continues the process. In addition, when the control end operation has been performed, the alloying control apparatus 100 ends the control of the alloying furnace.

  By carrying out the processing in the flow as described above, in the hot dip galvanizing line 1 according to the present embodiment, the fluctuation of the operation for producing the alloyed hot dip galvanized steel sheet is followed, and the alloying of the plating layer is stabilized. Can be controlled.

(Second Embodiment)
1st Embodiment of this invention demonstrated above controls alloying of the plating layer formed in the steel plate based on the emissivity of at least four places where the steel plates conveyed on the hot dip galvanizing line are different from each other. It was something to do. 2nd Embodiment of this invention demonstrated below controls alloying of the plating layer formed in the steel plate based on the emissivity which measured the same location of the steel plate conveyed by the hot dip galvanizing line. is there.

<About hot dip galvanizing line>
First, an outline of a hot dip galvanizing line according to the second embodiment of the present invention will be described with reference to FIGS. 7 and 8. FIG. 7 is an explanatory view showing an outline of a hot dip galvanizing line according to the present embodiment. FIG. 8 is an explanatory diagram for explaining the emissivity measurement method according to the present embodiment.

  Regarding the zinc bath 10, the alloying furnace 20, the retentive zone 30, the cooling zone 40, and the alloying furnace control means 60 provided in the hot dip galvanizing line 1 according to the present embodiment, the zinc bath 10 according to the first embodiment. The alloying furnace 20, the retentive zone 30, the cooling zone 40, and the alloying furnace control means 60 have the same configuration and exhibit the same effects, and thus detailed description thereof is omitted.

  In the hot dip galvanizing line 1 according to the present embodiment, one alloying sensor 50 is installed in the vicinity of the tropical zone 30. Further, as shown in FIG. 8, the alloying sensor 50 is connected to a sensor position changing means 70 such as a belt conveyor, and the position thereof can be changed in accordance with the conveying speed of the steel sheet S. ing. Thereby, the alloying sensor 50 which concerns on this embodiment can measure the same position of a steel plate, moving the predetermined area of the tropical rain 30 with the steel plate S. FIG. As shown in FIG. 8, the alloying sensor 50 according to the present embodiment continuously measures the steel sheet S in the section between the measurement start position SA and the measurement end position SB, and alloyes the obtained measurement results. Output to the control device 100.

  Here, the measurement start position SA of the alloying sensor 50 shown in FIG. 8 is preferably in the vicinity of the entrance side of the retentive zone 30, and more preferably about 5 m from the entrance to the retentive location. The measurement end position SB of the alloying sensor 50 is about several meters later than the measurement start position SA (position about one second after passing through the measurement start position SA) so that it falls within the first half of the retentive zone 30. It is preferable to set.

  The alloying control apparatus 100 according to the present embodiment includes the steel plate measurement information output from the alloying sensor 50 and the presence position of the alloying sensor 50 output from the sensor position changing means 70 (that is, the alloying sensor is currently measured). Information on the position where Then, the alloying control device 100 determines the alloying of the plating layer formed on the steel sheet S, and controls the output of the alloying furnace 20 when appropriate alloying is not progressing. To allow proper alloying to proceed.

  Note that the sensor position changing means 70 shown in FIG. 8 is merely an example, and any one can be used as long as the position can be changed according to the conveying speed of the steel sheet S.

<About the structure of the alloying control device>
Next, the configuration of the alloying control apparatus 100 according to the present embodiment will be described in detail with reference to FIG. FIG. 9 is a block diagram showing the configuration of the alloying control apparatus according to the present embodiment.

  As shown in FIG. 9, the alloying control apparatus 100 according to the present embodiment includes, for example, a steel plate measurement information acquisition control unit 101, an emissivity calculation unit 103, a display control unit 111, a storage unit 113, and an emissivity difference calculation unit. 151, the alloying determination part 153, and the alloying furnace control part 155 are mainly provided.

  The steel plate measurement information acquisition control unit 101 according to the present embodiment acquires steel plate measurement information from the alloying sensor 50 while acquiring information related to the current position of the alloying sensor 50 from the sensor position changing unit 70, and the alloying sensor 50. The present embodiment has the same configuration as the steel plate measurement information acquisition control unit 101 according to the first embodiment except that the current position and the acquired steel plate measurement information are output in association with each other. Therefore, detailed description is omitted below.

  The emissivity calculation unit 103 according to the present embodiment is the same as the emissivity calculation unit 103 according to the first embodiment, except that information regarding the calculated emissivity is output to the emissivity difference calculation unit 151 and the alloying determination unit 153. And having the same effect. Therefore, detailed description is omitted below.

  Further, the display control unit 111 and the storage unit 113 according to the present embodiment have the same configuration as the display control unit 111 and the storage unit 113 according to the first embodiment, and thus detailed description thereof will be omitted below.

  The emissivity difference calculation unit 151 according to the present embodiment is realized by, for example, a CPU, a ROM, a RAM, and the like. The emissivity difference calculation unit 151 calculates the emissivity difference between the measurement end position SB and the measurement start position SA based on the emissivities at the measurement start position SA and the measurement end position SB calculated by the emissivity calculation unit 103. calculate. The emissivity difference calculation unit 151 outputs the calculated emissivity difference to the alloying determination unit 153 described later.

  The alloying determination unit 153 is realized by, for example, a CPU, a ROM, a RAM, and the like. Based on the emissivity in the measurement interval calculated by the emissivity calculation unit 103 and the emissivity difference calculated by the emissivity difference calculation unit 151, the alloying determination unit 153 has a plating layer formed on the steel plate. It is determined whether or not alloyed.

  More specifically, the alloying determination unit 153 determines that the emissivity εA at the measurement start position SA exceeds the first threshold and the emissivity at the measurement end position SB as shown in (i) of FIG. If εB is less than the second threshold, it is determined that alloying is appropriate.

  In addition, as shown in FIG. 10 (ii), the alloying determination unit 153 has an emissivity εA at the measurement start position SA that is equal to or higher than the third threshold, and is already suspected of being alloyed at the measurement start position SA. When it has a value, the alloying determination unit 153 determines that it is in an overalloy state.

  Further, as shown in (iii) of FIG. 10, the alloying determination unit 153 has an emissivity εB at the measurement end position SB that is equal to or lower than the fourth threshold value, and no alloying occurs at the measurement end position SB. If it has a low value that is suspected, the alloying determination unit 153 determines that it is in an unalloyed state.

  Note that the above four types of threshold values are values defined for each steel type, and the alloying determination unit 153 refers to the alloying-related database stored in the storage unit 113 and the like to determine what value the threshold value is. Determine if it exists.

  Further, in addition to the above-described determination criteria, the alloying determination unit 153 has a case where the difference in emissivity calculated by the emissivity difference calculation unit 151 increases with time, and the increase amount is equal to or greater than a predetermined threshold ( That is, when the emissivity difference calculated at time t2 is a value greater than or equal to a predetermined threshold value compared to the emissivity difference calculated at time t1, the hot dip galvanizing line 1 is excessive. Judged to be alloying.

  The alloying determination unit 153 outputs information representing the determination result as described above to the alloying furnace control unit 155. Further, the alloying determination unit 153 may output information on the determination result to the display control unit 111 to display the specific result on a display unit (not shown) such as a display. The alloying determination unit 153 may associate time information related to the date and time when such information is generated with information related to the determination result, and store the information in the storage unit 113 as history information.

  The alloying furnace control unit 155 is realized by, for example, a CPU, a ROM, a RAM, a communication device, and the like. The alloying furnace control unit 155 controls the alloying furnace so that the plating layer is alloyed in a desired region according to the determination result of alloying by the alloying determination unit 153.

  Specifically, when the alloying determination unit 153 determines that the alloy is in the overalloy state, the alloying furnace control unit 155 avoids the alloying state, and alloying occurs in a desired region. In order to do so, the power of the alloying furnace is reduced. Further, when it is determined that the alloying determination unit 153 is in an unalloyed state, the alloying furnace control unit 155 avoids being in an unalloyed state and causes alloying to occur in a desired region. Therefore, the power of the alloying furnace is increased. Further, when the alloying determination unit 153 determines that there is a tendency to overalloy, the alloying furnace control unit 155 reduces the output of the alloying furnace in order to avoid an overalloy state.

  Here, the control for increasing or decreasing the output of the alloying furnace may be appropriately selected according to the type of the alloying furnace to be used. For example, the maximum temperature setting value TH of the alloying furnace is set. What is necessary is just to increase / decrease or to increase / decrease the output (for example, the amount of electric current etc. which flows into a heater) of the heating apparatus for heating an alloying furnace.

  Further, the degree of increasing / decreasing the output of the alloying furnace may be appropriately selected according to the type of the alloying furnace used, the size of the equipment, the steel type, etc., for example, in the overalloyed state / unalloyed state. In some cases, the maximum temperature set value TH of the alloying furnace may be increased / decreased by 5 ° C., or the amount of current flowing through the heater may be increased / decreased by 2.5%. Further, when the alloy tends to be overalloyed, the maximum temperature set value TH of the alloying furnace may be reduced by 3 ° C., or the amount of current flowing through the heater may be reduced by 1.5%.

  When the alloying furnace control unit 155 selects a control method as described above according to the determination result, the alloying furnace control unit 155 generates a control signal corresponding to the selected control method and outputs the control signal to the alloying furnace control means 60. The alloying furnace control means 60 controls the alloying furnace 20 based on the control signal output from the alloying furnace control unit 155. Thereby, the alloying furnace 20 is controlled so that the alloying position is in a desired region.

Heretofore, the alloying control apparatus 100 according to the present embodiment has been described in detail.
Note that the alloying control apparatus 100 according to the present embodiment may continuously perform various determinations regarding alloying, or intermittently perform various determinations regarding alloying at predetermined time intervals. Also good.

  Moreover, the alloying control apparatus 100 according to the present embodiment measures the emissivity only at two positions of the measurement start position and the measurement end position (the two positions are movable), and between the measurement start position and the measurement end position. The alloying furnace may be controlled so as to cause alloying.

  Heretofore, an example of the function of the alloying control device 100 according to the present embodiment has been shown. Each component described above may be configured using a general-purpose member or circuit, or may be configured by hardware specialized for the function of each component. In addition, the CPU or the like may perform all functions of each component. Therefore, it is possible to appropriately change the configuration to be used according to the technical level at the time of carrying out the present embodiment.

  A computer program for realizing each function of the alloying control apparatus according to the present embodiment as described above can be produced and installed in a personal computer or the like. In addition, a computer-readable recording medium storing such a computer program can be provided. The recording medium is, for example, a magnetic disk, an optical disk, a magneto-optical disk, a flash memory, or the like. Further, the above computer program may be distributed via a network, for example, without using a recording medium.

<About the alloying control method>
Next, the flow of the alloying control method according to the present embodiment will be described with reference to FIG. FIG. 11 is a flowchart illustrating an example of the flow of the alloying control method according to the present embodiment.

  First, one alloying sensor 50 provided in the vicinity of the hot dip galvanizing line 1 measures the emissivity of the same portion of the steel sheet S in a predetermined section of the retentive zone 30 (step S151), and the alloying control device 100. Output to. Here, when the alloying sensor 50 is a sensor that measures a physical quantity that can be used for calculating the emissivity, not the emissivity of the steel sheet, as described above, the emissivity calculating unit of the alloying control apparatus 100. In step 103, the emissivity of the steel sheet may be calculated based on the information obtained as a result of the measurement.

  The emissivity difference calculation unit 151 of the alloying control apparatus 100 calculates the emissivity difference between the measurement start position and the measurement end position based on the measured emissivity of the steel sheet (step S153). The calculated result is output to the alloying determination unit 153.

  Based on the emissivity calculated by the emissivity calculation unit 103 and the emissivity difference calculated by the emissivity difference calculation unit 151, the alloying determination unit 153 determines whether or not the plating layer formed on the steel sheet is alloyed. (Step S155), and the obtained determination result is output to the alloying furnace control unit 155.

  The alloying furnace control unit 155 refers to the determination result in the alloying determination unit 153 to determine what control is to be performed (step S157). That is, the alloying furnace control unit 155 avoids the overalloy state when the determination result is in the overalloy state and tends to be overalloyed, so that the alloying occurs in a desired region. The control for reducing the output of is performed (step S159). Further, when the determination result is an unalloyed state, the alloying furnace control unit 155 avoids the unalloyed state and performs control to increase the output of the alloying furnace so that alloying occurs in a desired region. Implement (step S161). The alloying furnace control unit 155 does not change the setting of the alloying furnace when the difference in emissivity satisfies a predetermined condition and appropriate alloying is in progress.

  After performing such control, the alloying furnace control unit 155 determines whether or not to end the control of the alloying furnace (step S163). If the user or the like of the alloying control device 100 has not performed an operation to end the control, the alloying control device 100 returns to step S151 and continues the process. In addition, when the control end operation has been performed, the alloying control apparatus 100 ends the control of the alloying furnace.

  By carrying out the processing in the flow as described above, in the hot dip galvanizing line 1 according to the present embodiment, the fluctuation of the operation for producing the alloyed hot dip galvanized steel sheet is followed, and the alloying of the plating layer is stabilized. Can be controlled.

(About hardware configuration)
Next, the hardware configuration of the alloying control apparatus 100 according to the embodiment of the present invention will be described in detail with reference to FIG. FIG. 12 is a block diagram for explaining a hardware configuration of the alloying control apparatus 100 according to the embodiment of the present invention.

  The alloying control apparatus 100 mainly includes a CPU 901, a ROM 903, and a RAM 905. The alloying control device 100 further includes a bus 907, an input device 909, an output device 911, a storage device 913, a drive 915, a connection port 917, and a communication device 919.

  The CPU 901 functions as an arithmetic processing device and a control device, and controls all or a part of the operation in the alloying control device 100 according to various programs recorded in the ROM 903, the RAM 905, the storage device 913, or the removable recording medium 921. . The ROM 903 stores programs used by the CPU 901, calculation parameters, and the like. The RAM 905 primarily stores programs used by the CPU 901, parameters that change as appropriate during execution of the programs, and the like. These are connected to each other by a bus 907 constituted by an internal bus such as a CPU bus.

  The bus 907 is connected to an external bus such as a PCI (Peripheral Component Interconnect / Interface) bus via a bridge.

  The input device 909 is an operation unit operated by the user, such as a mouse, a keyboard, a touch panel, a button, a switch, and a lever. Further, the input device 909 may be, for example, remote control means (so-called remote control) using infrared rays or other radio waves, or an external connection device 923 such as a PDA corresponding to the operation of the alloying control device 100. There may be. Furthermore, the input device 909 includes, for example, an input control circuit that generates an input signal based on information input by a user using the operation unit and outputs the input signal to the CPU 901. The user of the alloying control device 100 can input various data and instruct a processing operation to the alloying control device 100 by operating the input device 909.

  The output device 911 is configured by a device that can notify the user of the acquired information visually or audibly. Examples of such devices include CRT display devices, liquid crystal display devices, plasma display devices, EL display devices and display devices such as lamps, audio output devices such as speakers and headphones, printer devices, mobile phones, and facsimiles. The output device 911 outputs results obtained by various processes performed by the alloying control device 100, for example. Specifically, the display device displays the results obtained by various processes performed by the alloying control device 100 as text or an image. On the other hand, the audio output device converts an audio signal composed of reproduced audio data, acoustic data, and the like into an analog signal and outputs the analog signal.

  The storage device 913 is a data storage device configured as an example of a storage unit of the alloying control device 100. The storage device 913 includes, for example, a magnetic storage device such as an HDD (Hard Disk Drive), a semiconductor storage device, an optical storage device, or a magneto-optical storage device. The storage device 913 stores programs executed by the CPU 901, various data, various data acquired from the outside, and the like.

  The drive 915 is a recording medium reader / writer, and is built in or externally attached to the alloying control apparatus 100. The drive 915 reads information recorded on a removable recording medium 921 such as a mounted magnetic disk, optical disk, magneto-optical disk, or semiconductor memory, and outputs the information to the RAM 905. The drive 915 can also write a record on a removable recording medium 921 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory. The removable recording medium 921 is, for example, a CD medium, a DVD medium, a Blu-ray medium, or the like. The removable recording medium 921 may be a CompactFlash (registered trademark) (CompactFlash: CF), a flash memory, an SD memory card (Secure Digital memory card), or the like. Further, the removable recording medium 921 may be, for example, an IC card (Integrated Circuit card) on which a non-contact IC chip is mounted, an electronic device, or the like.

  The connection port 917 is a port for directly connecting a device to the alloying control device 100. Examples of the connection port 917 include a USB (Universal Serial Bus) port, an IEEE 1394 port, a SCSI (Small Computer System Interface) port, and an RS-232C port. By connecting the external connection device 923 to the connection port 917, the alloying control apparatus 100 acquires various data directly from the external connection device 923 or provides various data to the external connection device 923.

  The communication device 919 is a communication interface configured with, for example, a communication device for connecting to the communication network 925. The communication device 919 is, for example, a communication card for wired or wireless LAN (Local Area Network), Bluetooth (registered trademark), or WUSB (Wireless USB). The communication device 919 may be a router for optical communication, a router for ADSL (Asymmetric Digital Subscriber Line), or a modem for various communication. The communication device 919 can transmit and receive signals and the like according to a predetermined protocol such as TCP / IP, for example, with the Internet and other communication devices. The communication network 925 connected to the communication device 919 is configured by a wired or wireless network, and may be, for example, the Internet, a home LAN, infrared communication, radio wave communication, satellite communication, or the like. .

  Heretofore, an example of the hardware configuration capable of realizing the function of the alloying control apparatus 100 according to the embodiment of the present invention has been shown. Each component described above may be configured using a general-purpose member, or may be configured by hardware specialized for the function of each component. Therefore, it is possible to change the hardware configuration to be used as appropriate according to the technical level at the time of carrying out this embodiment.

<About alloying sensor and emissivity calculation method>
Prior to describing the embodiment of the present invention, first, the alloying sensor used in the first and second embodiments described below, and the emissivity calculation method using the output data of the alloying sensor. explain.

  In the embodiment described below, a radiation thermometer is used as the alloying sensor. This radiation thermometer measures the radiance of a steel sheet conveyed through a hot dip galvanizing line. Below, the outline is demonstrated about the calculation method of the emissivity based on the measured radiance which the emissivity calculating part 103 implements.

In the following description, it is assumed that the z-axis positive direction is the conveyance direction of the steel sheet S, the steel plate temperature is T _p (z) [° C.], and the emissivity is ε (z) inside the retentive zone 30. It is assumed that the steel plate S is being conveyed. Further, it is assumed that the inner wall (heat insulating material) of the retentive zone 30 is heated by thermal radiation of the steel sheet S conveyed at a high temperature, and the inner wall temperature reaches T _W (z) [° C.].

  Here, the radiation thermometer which is the alloying sensor 50 installed in the vicinity of the retentive zone 30 measures thermal radiation (that is, self-luminous) emitted by the steel sheet S. In addition, since the inner wall (insulating material) of the tropical zone has heat, the inner wall of the tropical zone also emits heat radiation. This thermal radiation is reflected by the steel sheet S and is simultaneously observed by the radiation thermometer as stray light. Thus, the radiance L (z) observed by the radiant thermometer is the sum of the radiance due to the self-luminance of the steel sheet and the radiance due to the thermal radiation of the inner wall, as shown in the following equation 101.

・・・（式１０１）

... (Formula 101)

  Here, in the above formula 101, ε (z) represents the true emissivity of the steel sheet, and L (z) is the radiance measured by the radiation thermometer. Further, the first term on the right side represents the radiance due to self-emission from the steel sheet S at the position z, and the second term on the right side represents the radiance (that is, the heat radiation from the inner wall of the tropical zone reflected and mixed into the steel plate (that is, Stray light noise).

Here, L _p (z) and L _w (z) in the above equation 101 are expressed as the following equations 102 and 103, respectively. In the following formulas 102 and 103, the constant c ₁ is a value expressed using the light velocity c in vacuum and the Planck constant h, and the constant c ₂ is the light velocity c in vacuum. , And a Plank constant h and a Boltzmann constant k. Details of these values are shown in Equation 104 and Equation 105 below. Λ is the observation wavelength of the radiation thermometer, and is a value set in the infrared region (more specifically, the near infrared region, for example, 1.5 μm).

・・・（式１０２）

・・・（式１０３）

・・・（式１０４）

・・・（式１０５）

... (Formula 102)

... (Formula 103)

... (Formula 104)

... (Formula 105)

Here, the steel plate temperature T _p (z) existing in the equation 102 and the wall surface temperature T _w (z) existing in the equation 103 can be specified by a method as outlined below. is there. The emissivity calculation unit 103 calculates the radiance expressed by the above formulas 102 and 103 using such temperature values and the constants c ₁ , c _2, and λ.

When the calculation of the radiance based on the above formulas 102 and 103 is completed, the emissivity calculation unit 103 uses the measured value of the radiation thermometer output from the steel plate measurement information acquisition control unit 101 to calculate the following formula 106: Based on this, the emissivity ε (z) is calculated. Note that, in the alloying process that has recently been introduced as noted in this embodiment, the wall surface temperature is lower than the steel plate temperature, and L _p (z) ≠ L _w (z) is established. ing.

・・・（式１０６）

... (Formula 106)

  The emissivity calculation unit 103 can accurately calculate the emissivity based on the measurement value related to the radiance obtained from the radiation thermometer by using the method described above.

In the alloying process that has been introduced in recent years, the difference between the steel plate temperature and the wall surface temperature may increase. In such a case, the value of L _w (z) represented by Expression 103 is sufficiently smaller than L _p (z) represented by Expression 102, and therefore L _w (z) is ignored in Expression 106 above. The following expression 107 may be used.

・・・（式１０７）

... (Formula 107)

[Steel temperature T _p (z)]
The steel plate temperature Tp (z) is obtained by using the information related to the temperature drop pattern of the steel plate accompanying the change in the transport direction position of the steel plate and the information related to the installation position of the radiation thermometer. It can be calculated as an estimated value of temperature.

  Here, the information on the steel plate temperature decrease pattern (hereinafter, also simply referred to as “steel plate temperature decrease pattern”) is obtained from the past operation result data for each condition such as the manufacturing conditions, that is, the steel type, thickness, and conveyance speed of the steel plate. In addition, it is stored in the storage unit 113 in advance. Alternatively, the steel plate temperature decrease pattern can be calculated from a heat transfer model simulation result of heat removal of the steel plate by the furnace atmosphere and the inner wall. In this case, since the simulation by the heat transfer model is calculated in the form of a temperature drop with respect to the passage of time of the steel sheet transport inside the retentive zone 30, in that case, it is combined with the information on the transport speed to transport the steel sheet. A temperature drop pattern of the steel sheet accompanying the change in the direction position is calculated.

  Such a steel plate temperature decrease pattern is stored in the storage unit 113, for example. The steel plate temperature decrease pattern may be stored in the storage unit 113 in the form of a database for each type of steel plate, or may be stored in the storage unit 113 in the form of a lookup table for each type of steel plate.

  As such a steel plate temperature decrease pattern, the slope of a straight line indicating the degree of decrease in the steel plate temperature inside the retentive zone 30 can be used. The straight line indicating the degree of decrease in the steel plate temperature can be represented as a straight line in a coordinate system defined by the distance from the tropical retentive entry side and the steel plate temperature (° C.). That is, the distance from the tropical retreat entry side corresponds to the installation position of the radiation thermometer.

By using such a straight line, the emissivity calculation unit 103 calculates the temperature decrease amount of the steel sheet based on the installation position (z coordinate) of the radiation thermometer. For example, if the steel plate temperature decrease pattern is known as an inclination representing the degree of decrease in the steel plate temperature, the emissivity calculation unit 103 first calculates the temperature decrease amount ΔT using the distance from the tropical retentive entry side. calculate. Next, the emissivity calculation unit 103 is calculated from the steel plate temperature T ₀ immediately before being carried into the retentive zone 30 calculated using the radiance L ₀ of the radiation thermometer at the measurement position S1 or the measurement start position SA. Subtract the temperature drop amount ΔT. Thereby, the estimated steel plate temperature T _p (z) at the position z in the tropical region can be calculated. That is, the estimated steel plate temperature is an amount represented by T _p (z) = T ₀ −ΔT. Note that the temperature T ₀ is before the start of alloying at this position, so that the emissivity is 0.2 (or more precisely 0.17), and the observed radiance L ₀ is observed. Can be obtained by converting to temperature.

[Wall temperature T _w (z)]
The steel plate temperature Tp (z) is obtained by using, for example, an output (wall surface temperature) from a wall surface thermometer installed in the tropical region 30 and information on the installation position of the wall surface thermometer stored in the storage unit 113 or the like. The wall surface temperature at the required position can be calculated by linear interpolation.

That is, if the wall surface temperature at at least two locations, for example, the wall surface temperature T _w (z ₁ ) at z = z _{1 and} the wall surface temperature T _w (z ₂ ) at z = z ₂ are measured, the wall surface temperature It is possible to define a straight line representing the transition of. Therefore, the emissivity calculation unit 103 uses the acquired wall surface temperature to calculate an equation that gives the wall surface temperature at an arbitrary position (z coordinate position), and uses the equation to calculate the wall temperature at a required position. Calculate the wall temperature.

  Here, the emissivity calculation unit 103 may perform wall surface temperature calculation by nonlinear interpolation instead of wall surface temperature calculation by linear interpolation.

<First embodiment>
In the following examples, mild steel having a plate width of 1100 mm and a thickness of 0.7 mm was used, and the mild steel was conveyed on the hot dip galvanizing line 1 at a plate passing speed of 120 mpm. Here, the temperature of the zinc bath was 450 ° C., and the maximum temperature of the alloying furnace was 515 ° C.

  Moreover, the alloying furnace 20 in the hot dip galvanizing line 1 in the present embodiment has a height of 9 m as shown in FIG. 13, and the retentive zone 30 is as shown in FIG. It had a height of 50 m. Further, as shown in FIG. 13, four radiation thermometers were used to calculate the emissivity, and the separation distance between adjacent radiation thermometers was 8 m, respectively.

[Stable operation]
The average difference in emissivity at the measurement position S3 and measurement position S2 during the measurement time (about 1600 minutes / 40 coils: non-continuous) was 0.55, indicating a stable value as an appropriate alloy of mild steel. Here, although the measurement of the radiation thermometer was continuously performed, the determination of alloying was performed every minute, and the difference average of emissivity was calculated using the value of about 1700 points. The overalloy ratio at this time was 0%, and the unalloyed ratio was 0%.

  The overalloy rate is the length of the overalloy (the length of the overalloy determined by the determination process after cooling in the subsequent stage of the hot dip galvanizing line 1 and removed) / the effective total length (about 200 km for 40 coils: It is a numerical value expressed by × 100. Further, the unalloyed ratio is the unalloyed length (the length that has been unalloyed and removed by the determination process after cooling in the subsequent stage of the hot dip galvanizing line 1) / the effective total length (about 200 km for 40 coils: It is a numerical value expressed by × 100.

[When judging unalloyed]
During the measurement time (about 40 minutes / one coil), the difference in emissivity between the measurement position S3 and the measurement position S4 was 0.25. Here, in this embodiment, in order to make a fine determination, less than 0.20 is an appropriate area, 0.20 or more and less than 0.25 is a caution area, and 0.25 is a threshold value or more, an adjustment execution area or more. Was set. Therefore, output adjustment was performed once so that the induction heater current in the alloying furnace 20 was + 2.5%.

  The difference in emissivity in the next measurement after output adjustment returned to less than 0.25, but it took 15 minutes for the difference between the measurement position S3 and the measurement position S4 to be less than 0.20. The unalloyed ratio of the coil was 1%.

[When overalloy is judged]
During the measurement time (about 40 minutes / one coil), the emissivity difference between the measurement position S1 and the measurement position S2 was 0.29. As described above, in this embodiment, in order to make fine determination, less than 0.20 is an appropriate area, 0.20 or more and less than 0.25 is an attention area, and 0.25 is a threshold value or more. Area, and was set. Therefore, output adjustment was performed once so that the induction heater current in the alloying furnace 20 was -2.5%.

  The emissivity difference in the next measurement after the output adjustment has returned to less than 0.25, but it takes 20 minutes for the difference between the measurement position S1 and the measurement position S2 to be less than 0.20. The overalloy ratio of the coil was 2%.

<Second embodiment>
In the following examples, mild steel having a plate width of 1100 mm and a thickness of 0.7 mm was used, and the mild steel was conveyed on the hot dip galvanizing line 1 at a plate passing speed of 120 mpm. Here, the temperature of the zinc bath was 450 ° C., and the maximum temperature of the alloying furnace was 515 ° C.

  Moreover, the alloying furnace 20 in the hot dip galvanizing line 1 in the present embodiment has a height of 9 m as shown in FIG. 14, and the retentive zone 30 is as shown in FIG. It had a height of 50 m. Further, as shown in FIG. 14, the steel sheet was measured with one radiation thermometer in a section of 1 m from a position 2 m from the entrance side of the retentive zone 30.

  In this example, in order to continuously measure one point of the steel plate S, a radiation thermometer that moves in parallel with the steel plate was installed on the belt conveyor. At this time, in order to avoid a blank in the time zone until the position of the radiation thermometer returns, two radiation thermometers were installed at positions facing each other on the belt conveyor. Although the parallel section (that is, the measurement section) is set to 1 m due to installation space and heat radiation limitations, if a longer section can be measured, the measurement accuracy can be further improved.

[Stable operation]
The average difference in emissivity between the measurement start position SA and the measurement end position SB during the measurement time (about 400 minutes / ten coils: non-continuous) is 0.54, which is a stable value as an appropriate alloy of mild steel. Indicated. Here, the time required for one measurement was 0.5 seconds. The overalloy ratio at this time was 0%, and the unalloyed ratio was 0%. The overalloy rate and unalloyed rate are the same as defined in the first embodiment.

[When judging unalloyed]
Three times during the measurement time (about 40 minutes / one coil), an emissivity at the measurement start position SA was less than 0.25 and an emissivity at the measurement end position SB was 0.35 or less. . Therefore, output adjustment was performed so that the induction heater current in the alloying furnace 20 was + 2.5%. In the next measurement after the output adjustment, the emissivity at the measurement end position SB returned to exceed 0.35. The unalloyed ratio of this coil was 0.1%. The control conditions (conditions relating to the emissivity threshold) in the present embodiment will be described collectively below.

[When overalloy is judged]
A situation in which the emissivity at the measurement start position SA was 0.40 or more once during the measurement time (about 40 minutes / one coil). Here, in the present embodiment, in order to make a fine determination, less than 0.35 is an appropriate region, 0.35 or more and less than 0.40 is a caution region, and 0.40 is a threshold value or more, an adjustment execution region, Was set. Therefore, output adjustment was performed once so that the induction heater current in the alloying furnace 20 was -2.5%. In the next measurement after the output adjustment, the emissivity at the measurement end position SA returned to less than 0.40, but it took 7 minutes until the emissivity at the measurement start position SA became less than 0.35. The overalloy ratio of the coil was 0.1%.

The conditions relating to the emissivity threshold in this embodiment are as follows.
First threshold at SA (although less than this value, alloying is appropriate): 0.25
SB second threshold (if this value is exceeded, alloying is appropriate): 0.35
Third threshold value at SA (over this value, overalloying): 0.40
SB fourth threshold (below this value, not alloyed): 0.20

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Hot dip galvanizing line 10 Zinc bath 20 Alloying furnace 30 Heat retention 40 Cooling zone 50 Alloying sensor 60 Alloying furnace control means 70 Sensor position change means 101 Plywood measurement information acquisition control part 103 Emissivity calculation part 105,151 Emissivity Difference calculation unit 107 Alloying position specifying unit 109, 155 Alloying furnace control unit 111 Display control unit 113 Storage unit 153 Alloying determination unit

Claims (9)

For the steel sheet transported through the hot dip galvanizing line, the emissivity in the first half of the retentive zone of the hot dip galvanizing line is in order from the side closer to the alloying furnace provided in the front stage of the retentive zone along the steel sheet transport direction. An emissivity measurement step for measuring at at least four measurement positions as S1, S2, S3, S4 .
Based on the measurement result of the emissivity, a difference calculating step for calculating the difference of the emissivity between the measurement positions adjacent to each other, and
An alloy in which the plating layer provided on the steel sheet is alloyed based on whether or not the calculated difference in emissivity is equal to or greater than a predetermined threshold, and the plating layer is alloyed in the retentive zone An alloying determination step for identifying the alloying region;
Alloying for controlling the output of the alloying furnace provided in the previous stage of the retentive zone so that the plating layer is alloyed between the measurement position S2 and the measurement position S3 according to the specified position of the alloying region. Furnace control step;
Including
The measurement position S2 is set inside the retentive zone,
The measurement position S3 is set to a position calculated based on the position of the measurement position S2, the emissivity change pattern of the steel plate, and the conveyance speed of the steel plate,
In the emissivity measurement step,
Based on the measurement result L of the radiance by the radiation thermometer at each of the measurement positions, the steel plate temperature T _p calculated based on the temperature drop pattern of the steel plate, and the wall temperature T _w of the retentive zone, The emissivity is calculated by Equations 1 to 3,
In the alloying furnace control step,
In the case where the alloying region is located in a preceding stage than between the measurement position S2 and the measurement position S3 , the output of the alloying furnace is reduced,
When the alloying region is located at a later stage than between the measurement position S2 and the measurement position S3 , an output of the alloying furnace is increased.

Here, in the above formulas 1 to 3,
z: Measurement position
ε: Emissivity
L: Measurement result of radiance by radiation thermometer
L _p : Radiance due to self-emission from steel plate
L _w : Radiance due to thermal radiation from the inner wall of the tropical zone
T _p : steel plate temperature
T _w : Wall temperature in the tropical zone
c ₁ , c ₂ : constant
λ: Observation wavelength of radiation thermometer
It is.
In the alloying determination step, the steel sheet feature data including the difference of the previous SL emissivity by referring to the database described for each type of steel sheet, said plating layer and judging whether alloyed, The alloying control method according to claim 1 . 2. The alloying according to claim 1 , wherein a measurement position of the emissivity after the fifth position is set between the measurement position S <b> 1 and the measurement position S <b> 2 or between the measurement position S <b> 3 and the measurement position S <b> 4. Control method. The alloying control method according to any one of claims 1 to 3 , wherein a furnace temperature set value or an output of the alloying furnace is changed at predetermined time intervals. Emissivity measurement for a steel sheet transported through a hot dip galvanizing line , and measuring the emissivity in the first half of the hot dip in the hot dip galvanizing line over a predetermined section in the first half of the hot dip in the same location of the steel sheet. Steps,
Based on the measurement result of the emissivity, a difference calculating step of calculating a difference of the emissivity between the measurement start position and the measurement end position of the emissivity,
An alloying determination step for determining whether the plating layer provided on the steel sheet is alloyed by comparing the measured emissivity and the calculated difference between the emissivities with a predetermined threshold ;
In accordance with the determination result of the alloying, an alloying furnace control step for controlling the output of the alloying furnace provided in the preceding stage of the retentive zone so that the plating layer is alloyed within the predetermined section;
Including
In the emissivity measurement step,
Based on the measurement result L of the radiance by the radiation thermometer at each of the measurement positions, the steel plate temperature T _p calculated based on the temperature drop pattern of the steel plate, and the wall temperature T _w of the retentive zone, The emissivity is calculated by Equations 1 to 3,
In the alloying furnace control step,
If the emissivity at the measurement start position is above the first threshold, reduce the power of the alloying furnace,
The alloying control method, wherein when the emissivity at the measurement end position is less than a second threshold, the output of the alloying furnace is increased.

Here, in the above formulas 1 to 3,
z: Measurement position
ε: Emissivity
L: Measurement result of radiance by radiation thermometer
L _p : Radiance due to self-emission from steel plate
L _w : Radiance due to thermal radiation from the inner wall of the tropical zone
T _p : steel plate temperature
T _w : Wall temperature in the tropical zone
c ₁ , c ₂ : constant
λ: Observation wavelength of radiation thermometer
It is.
The alloying control method according to claim 5 , wherein, in the alloying furnace control step, when the difference in emissivity increases with time, the output of the alloying furnace is reduced. In the alloying determination step, it is determined whether or not the plating layer is alloyed by referring to a database in which the steel plate characteristic data including the first threshold value and the second threshold value is described for each type of steel plate. The alloying control method according to claim 5 or 6 , wherein: For the steel sheet transported through the hot dip galvanizing line, the emissivity in the first half of the retentive zone of the hot dip galvanizing line is in order from the side closer to the alloying furnace provided in the front stage of the retentive zone along the steel sheet transport direction. An emissivity calculation unit that calculates at least four measurement positions as S1, S2, S3, S4 .
An emissivity difference calculation unit that calculates the difference in emissivity between measurement positions adjacent to each other based on the measurement result of the emissivity,
An alloy in which the plating layer provided on the steel sheet is alloyed based on whether or not the calculated difference in emissivity is equal to or greater than a predetermined threshold, and the plating layer is alloyed in the retentive zone An alloying position specifying part for specifying an alloying region;
Alloying for controlling the output of the alloying furnace provided in the previous stage of the retentive zone so that the plating layer is alloyed between the measurement position S2 and the measurement position S3 according to the specified position of the alloying region. A furnace control unit;
With
The measurement position S2 is set inside the retentive zone,
The measurement position S3 is set to a position calculated based on the position of the measurement position S2, the emissivity change pattern of the steel plate, and the conveyance speed of the steel plate,
The emissivity calculator is
Based on the measurement result L of the radiance by the radiation thermometer at each of the measurement positions, the steel plate temperature T _p calculated based on the temperature drop pattern of the steel plate, and the wall temperature T _w of the retentive zone, The emissivity is calculated by Equations 1 to 3,
The alloying furnace controller is
In the case where the alloying region is located in a preceding stage than between the measurement position S2 and the measurement position S3 , the output of the alloying furnace is reduced,
The alloying control apparatus, wherein the output of the alloying furnace is increased when the alloying region is located at a later stage than between the measurement position S2 and the measurement position S3 .

Here, in the above formulas 1 to 3,
z: Measurement position
ε: Emissivity
L: Measurement result of radiance by radiation thermometer
L _p : Radiance due to self-emission from steel plate
L _w : Radiance due to thermal radiation from the inner wall of the tropical zone
T _p : steel plate temperature
T _w : Wall temperature in the tropical zone
c ₁ , c ₂ : constant
λ: Observation wavelength of radiation thermometer
It is.
Emissivity calculation for calculating the emissivity in the first half of the hot dip galvanizing line for the steel sheet transported through the hot dip galvanizing line over the predetermined section in the first half of the hot dip tempering for the same location of the steel sheet And
Based on the measurement result of the emissivity, an emissivity difference calculation unit that calculates the difference of the emissivity between the measurement start position and the measurement end position of the emissivity,
An alloying determination unit that determines whether the plating layer provided on the steel sheet has been alloyed by comparing a difference between the measured emissivity and the calculated emissivity with a predetermined threshold value ;
In accordance with the determination result of the alloying, an alloying furnace control unit that controls the output of the alloying furnace provided in the previous stage of the retentive zone so that the plating layer is alloyed within the predetermined section;
With
The emissivity calculator is
Based on the measurement result L of the radiance by the radiation thermometer at each of the measurement positions, the steel plate temperature T _p calculated based on the temperature drop pattern of the steel plate, and the wall temperature T _w of the retentive zone, The emissivity is calculated by Equations 1 to 3,
The alloying furnace controller is
If the emissivity at the measurement start position is above the first threshold, reduce the power of the alloying furnace,
The alloying control apparatus, wherein when the emissivity at the measurement end position is less than a second threshold, the output of the alloying furnace is increased.

Here, in the above formulas 1 to 3,
z: Measurement position
ε: Emissivity
L: Measurement result of radiance by radiation thermometer
L _p : Radiance due to self-emission from steel plate
L _w : Radiance due to thermal radiation from the inner wall of the tropical zone
T _p : steel plate temperature
T _w : Wall temperature in the tropical zone
c ₁ , c ₂ : constant
λ: Observation wavelength of radiation thermometer
It is.

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