KR19980052531A - Apparatus for controlling coating amount of plating using a plating amount profile and its control method - Google Patents

Abstract

The present invention relates to a plating amount control apparatus and a control method thereof using a plating amount profile, wherein when the plating amount sensor is in a mode for scanning the steel sheet in the width direction, the profile storing means stores an average value of the profile and profile at the previous scanning, It is checked whether or not the detection sensor is being scanned. The profile storage means extracts an adhesion amount corresponding to the portion, subtracts an average value from the extracted plating adhesion amount to calculate a deviation, and calculates the deviation as a correction amount, Subtracting it from the deposition amount, and outputting it as a feedback amount to the control means. Therefore, it is possible to calculate the value corresponding to the average value in the axial difference value of the plating amount, so that the feedback control can be performed even in the state where the average deposition amount is not detected by the deposition amount detection sensor, the switching time to the feedback control can be reduced, It is possible to calculate the plating deposition amount with high precision by correcting the value of the plating amount by the correction means, and it is possible to quickly switch the feedforward control to the feedback control and to increase the precision by using the plating deposition amount thus calculated as the feedback amount of the feedback control have.

Description

Apparatus for controlling coating amount of plating using a plating amount profile and its control method

The present invention relates to an apparatus and method for controlling a coating amount of a plating using a plating amount profile, and more particularly, to a method of controlling a coating amount of a steel sheet continuously moving in a steel cold rolling process for producing a plating product, The present invention relates to a plating adherence amount control apparatus and a control method thereof, which use a plating amount profile for controlling the amount of plating zinc by a target amount by correcting a plating adhesion amount according to a stored profile.

As a conventional technique for controlling the deposition amount of the plating, there is a method of controlling the nozzle gas pressure, the height of the nozzle, the gap between the nozzle and the steel plate using a control model equation or the like immediately after changing the specification of the deposition amount as described in Iron and Steel Engineer (June, 1994) And FEED FORWARD control is performed in accordance with the set value. After the specification changing point arrives at the plating deposition amount detection sensor and the deposition amount is detected, the deviation between the detected value and the target deposition amount is detected There is a method of performing FEED BACK control in the direction of reducing this deviation.

However, when there is a deviation between the value obtained when the control set value for the desired target plating amount is calculated in this feed forward and the actual state value of the controlled object, this causes a decrease in the accuracy of the deposition amount control. Therefore, in the plating amount control, it is preferable that the plating adhesion amount precision at the portion where the feedforward control is generally performed is lower than that at the portion where the feedback control is performed, so that it is preferable to switch to the feedback control as soon as possible after the specification change of the plating adhesion amount.

In addition, since the control set value is calculated by using the control model that is constructed in advance, it is not possible to reflect the change of the control target state or the control environment with the lapse of time, which causes the accuracy of the deposition amount control to be lowered.

Even when switching to the feedback control, the position of the nozzle and the position of the coating adhesion detecting sensor are distant (usually 50 m or more), and the control delay time becomes large. In addition, when a plating amount detection sensor is used as a plating amount average value output mode, a scanning time of several tens of seconds is required in order to obtain an average plating amount in the width direction, and therefore, there is a delay time according to the detection of the plating amount. Therefore, it is impossible to quickly switch to the feedback control because the feedforward control must be maintained while scanning the plating amount in the width direction.

In order to solve this problem, when the center position of the steel plate is used as the scanning mode, the detection delay time is greatly reduced, but the nonuniformity in the width direction of the plating amount is not considered, which causes the accuracy of the detection value to deteriorate.

An object of the present invention is to provide a plating adherence amount control apparatus using a plating amount profile for hot-dip galvanizing a continuously moving steel sheet in a steel cold rolling process and a control method thereof.

Another object of the present invention is to provide a plating adherence amount control apparatus using a plating amount profile that scans the plating amount detection sensor in the width direction of a steel sheet and performs a feedback control using a value of a sequential plating adhering amount and an average adhering amount in a width direction obtained at this time, And to provide a control method.

It is still another object of the present invention to provide a plating deposition amount control apparatus using a plating amount profile that stores a profile of a plating amount in a width direction of a steel sheet and performs feedback control by correcting the present deposition amount detected by the plating amount detection sensor with reference to the profile, And a control method thereof.

In order to achieve the above object, an apparatus according to the present invention includes a specification table for storing a target plating deposition amount data set in advance and a setting table for storing a target plating deposition amount setting value, A control calculation unit for calculating and outputting a control amount set value by a calculation using a predetermined model expression by the set value calculation means and for outputting the control amount set value in the control calculation unit, Calculating a deviation by subtracting an average value from the extracted plating deposition amount and correcting the deposition deposition amount measured by the plating deposition amount detection sensor by using the deviation as a correction amount to calculate a control amount input from the control calculation section as a feedback feedback amount, A predetermined calculation expression is set for the set value An air knife nozzle for adjusting the amount of gas injected in response to a control signal from the plating control unit to control zinc plating on the steel plate, and a control unit for controlling the air knife nozzle, And a plating deposition amount detecting sensor for detecting a deposition amount of plating adhered to the steel sheet discharged through the discharge port.

FIG. 1 is a block diagram showing a configuration of a plating amount control apparatus according to the present invention.

Fig. 2 is an embodiment of the operation of the plating deposition amount detecting means.

FIG. 3 is a flow chart showing a set value calculation operation process according to the present invention.

FIG. 4 is an embodiment of a flowchart showing a control method executed by the control means according to the present invention.

FIG. 5 is a flow chart showing a process executed by the correction coefficient calculation means according to the present invention.

FIG. 6 is a configuration diagram of the plating adhesion amount correcting means.

Description of the Related Art [0002]

100: plating control unit 103: observation means

104: Observation control means 107: Correction coefficient calculation means

108: profile storage means 109: deposition amount correction means

140: control calculation unit 141: specification table

142: set value calculating means 143: setting table

151: steel plate 152: input roll

153: Plating bath 154: Discharge roll

155: Air knife nozzle 156: Plated deposition amount detection means

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a plating amount control apparatus according to the present invention.

The apparatus according to the present invention is provided with a specification table 141 for storing a target plating deposition amount data set in advance and a setting table 143 for storing a target plating deposition amount setting value so that the specification table 141 and the setting table 143 A control calculation section (140) for calculating and outputting a control amount set value by calculation using a predetermined model expression on the basis of the extracted value, and a control calculation section The plating amount profile output from the plating amount detection sensor 156 installed in the apparatus 150 is stored and the deposition amount corresponding to the portion is extracted from the stored profile and the average value is subtracted from the extracted plating amount to calculate the deviation, And corrects the accumulated plating adhesion amount measured by the plating adhesion amount detecting sensor 156 using the spreading amount as a correction amount, A plating control unit 100 for calculating a plating control amount by executing a predetermined calculation formula on the control amount set value input from the control calculation unit 140 as a quantity and outputting a plating control signal, An air knife nozzle 155 for regulating the zinc plating attached to the steel plate 151 coming out of the plating bath 153 by adjusting the amount of gas to be injected through the air knife nozzle 155, And a plating deposition amount detection sensor 156 for detecting the plating deposition amount attached to the plating deposition amount sensor 156.

The operation and effect of the present invention will be described below.

The input roll 152 of the plating apparatus 150 moves the steel plate 151 in the direction of the arrow to be immersed in the plating bath 153 so that the steel plate 151 is plated with molten zinc contained therein. The steel strip 151 discharged from the plating bath 153 is partly melted and adhered to the surface of the steel strip 151 by the high pressure gas ejected from the air knife nozzle 155,

The plating apparatus 150 is provided with plating deposition amount detection means 156. FIG. 2 shows an embodiment of the operation of the plating deposition amount detecting means.

The plating deposition amount detection means 156 scans the steel strip 151 in the width direction and outputs the deposition amount detected at the timing when the scanning ends in the scanning direction and the width direction ends. The measured adhesion amount detected during scanning is the partial adhesion amount detected on a part of the scanning object on the steel sheet and the detected adhesion amount detected at the timing when the scanning ends is the detection of the average adhesion amount in the width direction. Actually, since the steel strip 151 is moving at the speed V, the coating deposit detection means 156 measures the steel strip 151 obliquely with respect to the steel strip 151 as shown in FIG. The plating deposition amount thus detected is transmitted to the plating control section 100.

In the present invention, the height H of the air knife nozzle 155 and the molten zinc bath surface, the distance D between the air knife nozzle 155 and the steel sheet, and the pressure P of the gas jetted by the air knife nozzle 155 And is shown as a control parameter of the air knife nozzle 155.

The control calculation unit 140 is provided with a specification table 141 in which the target amount of plating W1 is stored and a setting table 143 in which a part of the control settings are stored. The set value calculating means 142 searches for these and calculates the final gas pressure setting value P2, the interval setting value between the steel plate 151 and the air knife nozzle 155 D2), and the height setting value H2 of the zinc melt bath surface and the air knife nozzle 155 is calculated. These are output to the plating control section 100 through the communication interface section 144 and the network 130 together with the desired target plating amount W1.

The plating control section 100 outputs these values obtained through the communication interface section 101 to the plating apparatus 150 after appropriately correcting them as necessary. FIG. 1 shows a case where the interval D is set as the object of correction. The plating control section 100 outputs the gas pressure setting value P1 and the height setting value H1 of the air knife nozzle 155 obtained from the control calculation section 140 directly to the plating apparatus 150 from the control setting value. The detected plating amount W detected by the plating amount detection means 156 and obtained through the input means 102 is stored in the profile storage means 108 and output to the deposition amount correction means 109. [

The profile storage means 108 stores the partial deposition amount when the plating deposition amount detection means 156 scans the steel strip 151 in the width direction for the distance from the steel strip front end. The deposition amount correction means 109 refers to the contents of the profile storage means 108 and outputs to the control means 104 a value W0 obtained by correcting the plating deposition amount obtained through the input means 102. [

The control means 104 calculates the difference DELTA W between the output detected plating amount W0 of the deposition amount correction means 109 and the desired target plating amount W1 obtained by the control calculation unit 140 and uses the correction coefficient Ks And corrects the interval setting value D1 obtained from the control calculation unit 140. [ Then, the result of the correction is output to the plating apparatus 150 as a final gap control value D2. The height setting value H1 of the air knife nozzle 155 and the gas pressure setting value K ejected from the air knife nozzle 155 can be obtained by correcting the gap setting value D1 calculated by the control calculation unit 140, P1) and the like can be corrected.

FIG. 3 is a flowchart showing a set value calculation operation process according to the present invention.

The set value calculation operation is executed before the desired target plating amount set value W1 is changed or the welding point of the coil and coil in which the steel sheet is wound passes through the plating nozzle 155. [ The desired target plating amount setting value W1 is read in the specification table 141 in step S31. Table 1 shows one embodiment of the specification table.

[Table 1]

Table 1 shows that the first coating amount W1 of the coil 1 was 80 g / m 2, the coating amount W 1 of 300 m thereafter was 180 g / m 2, etc. do. The setting value calculating means 142 receives data such as the moving speed V of the steel sheet, the temperature of the hot-dip zinc and the temperature of the steel plate 151 from the plating control section 100 and passes through the position of the plating nozzle 155 The coil number of the steel plate 151 and the distance from the coil tip are recognized and the corresponding plating deposition amount set value W1 is extracted.

In step S32, the set value calculating means 142 uses the setting table 143 to determine the gas pressure set value P1 and the height set value H1. Table 2 shows an example of the setting table.

[Table 2]

In Table 2, an appropriate gas pressure setting value P1 and a height setting value H1 are displayed for the plating adhesion amount set value W1 and the moving speed V of the steel plate 151, respectively. The specification table 141 is determined according to the production schedule of the steel plate 151, and the setting table 143 is prepared in advance by the user on the basis of the current experience.

In step S33, the inverse function f- ¹ of f is used for f, which is a relational expression of the gas pressure P, the velocity V of the steel plate 151, the interval D, the height H and the plating deposition amount W at that time , W1, P1, and H1 are substituted for this

[Equation 1]

D1 = f- ¹ (W1, P1, V, H1)

The gap setting value D1 is calculated. As an example of the relationship f,

&Quot; (2) "

W = f (P, V, D, H) = 0.45P ^0.68 D ^0.88 V ^0.50 exp (8.3 / V) H ^0.01

The relationship of f is known

&Quot; (3) "

.

P1, D1, H1, and W1 calculated in step S34 to the plating control section 100 through the communication interface section 144. [ In the present embodiment, P1 and H1 are extracted from the setting table 143 and substituted into the model equation to determine D1. Alternatively, D1 and H1 may be extracted from the setting table 143 and P1 may be determined by the model equation. Combinations can also be extracted by the above process. It is also possible to omit some of the parameters if necessary. For example, when H1 is not a control target, it may be considered to calculate D1 by a model equation as follows.

&Quot; (4) "

FIG. 4 shows an embodiment of a flowchart showing a control method executed by the control means according to the present invention.

The observation control means 104 detects the deviation ΔW between the plating deposition amount set value W1 and the correction plating deposition amount W0 and corrects the interval setting value D1 calculated by the control calculation unit 140 according to the degree of the deviation do. This process will be described in detail as follows.

The deviation ΔW of the plating deposition amount is calculated by subtracting the correction plating deposition amount W0 output from the observation means 103 from the plating amount setting value W1 received from the control calculation unit 140 in step S41. V, H, D and the current state value of the plating apparatus 150 are different from each other when the control unit 140 calculates the control set value. In the present embodiment, the distance between the air knife nozzle 155 and the steel plate 151 is modified to reduce the influence to improve the degree of control.

In step S42, the interval correction amount? D is calculated using the deviation? W and the correction coefficient Ks. For example, when the correction coefficient Ks is an integer, it can be calculated as? D = Ks 占? W.

In step S43, when there is a correction history in the interval setting value D1, the correction amount? D, and the interval setting value D1 input from the control calculation unit 140 via the communication interface unit 101, the current gas pressure correction amount (D) prev to calculate the final spacing correction (D2) by D2 = D1 + (D) prev. When there is no correction history in the interval setting value D1, the interval correction value D2 is calculated by D2 = D1 +? D.

In step S44, the interval correction value D2 is output to the plating apparatus 150 via the output unit 105 to change the interval between the air knife nozzle 155 and the steel plate 151. [

FIG. 5 is a flowchart showing the process of the correction coefficient calculation means according to the present invention.

The correction coefficient calculation means 107 optimizes the value of the correction coefficient Ks. And receives the plating amount set value W1 from the control calculation unit 140 through the communication interface unit 101 in step S51. In step S52, the rate of change? D /? W of the gap with respect to the coating adhesion amount is calculated based on the plating amount set value W1. And the rate of change of the interval (? D /? W) = (P / 0.88 W1) when the model equation is expressed by the equation (2). The rate of change of the gap? D /? W can be calculated by substituting the plating amount set value W1 and the gap D into this equation. The correction coefficient calculation means 107 calculates the correction coefficient Ks of the observation control means 104 by calculating this value every time the plating amount set value W1 and the interval D are changed.

One embodiment of the profile storage means 108 is shown in Table 3.

[Table 3]

Profile storage means

In Table 3, it is shown that the value of the adhesion amount of the plating deposit detected at the portion of 100 g / m 2, 0.2 m detected at the 0.1 m portion from the edge of the steel sheet is 110 g / m 2 or the like.

And the average value of the detected amounts detected in the stored profile is 103 g / m 2. The content of the profile storage means 108 is obtained in the case where there is no change in the set value of the lower level and the state amount of the control target during the width direction scanning of the plating amount detection means 156 and is changed to a form overwriting the previous stored profile do. The plating adhesion amount correcting means 109 calculates the correction value of the partial adhesion amount from the partial adhesion amount of the steel plate 151 obtained by the input means 102 and the information stored in the profile storage means 108. [

FIG. 6 shows the configuration of plating amount correction means.

The plating adhesion amount detecting means 156 detects the partial adhesion amount W _temp and the distance from the front end of the steel plate when this value is detected. Next, the profile storage means 108 extracts the partial adhesion amount (W _temp-prev ) corresponding to the average value (W _ave-prev ) of the adhesion amount and the distance from the tip of the steel sheet at the working day. Then, ΔW obtained by subtracting the average partial adhesion amount (W _ave-prev ) of the adhesion amount from the adhesion amount (W _temp-prev ) is used as a correction amount and this value is subtracted from the partial adhesion amount W _temp to obtain the remaining amount (W _filtered ) And outputs it to the control means 104 as an amount. Thus, the difference between the adhesion amount in the width direction and the adhesion amount average is corrected by the correction, and a value corresponding to the average adhesion amount can be used as the feedback signal.

As described above, according to the present invention, a deviation is calculated by extracting an adhesion amount corresponding to a part being scanned, subtracting the average value of the profile storage means from the extracted adhesion amount, and calculating the deviation as a correction amount, It is possible to calculate the value corresponding to the average value in the axial difference value of the plating deposition amount. Therefore, even when the deposition amount detection sensor does not detect the average deposition amount, the feedback control can be performed using this value, The switching time to the control can be reduced. Further, the sequential output of the plating amount sensor for scanning the steel sheet in the width direction and the average value of these values can be stored in the profile storage means and the coating amount adjustment amount can be corrected by the plating amount correction means to calculate the plating amount with high accuracy. The feed forward control can be quickly switched to the feedback control and the precision can be increased by adjusting the position of the air knife nozzle with the calculated amount of plating deposition as the feedback amount of the feedback control.

Claims (5)

A plating amount control apparatus for a plating apparatus for plating a steel sheet produced in a steel cold rolling process, And a setting table for storing a target plating deposition amount set value, and based on the values extracted from the specification table and the setting table, the set value calculation means calculates the target plating deposition amount data A control calculation unit for calculating and outputting a control amount set value, A control unit that receives a target plating amount set value from the control calculation unit, stores a plating amount profile output from a plating amount detection sensor provided in the plating apparatus, extracts an amount of deposition corresponding to the target portion from the stored profile, And calculates a deviation, corrects the accumulated plating adhesion amount measured by the plating adhesion amount detecting sensor by using this deviation as a correction amount, and executes a predetermined calculation formula on the control amount set value inputted from the control calculation section as a feedback feedback amount, And outputs a plating control signal, An air knife nozzle for adjusting the amount of gas injected into the plating control unit to adjust the amount of gas to be sprayed on the steel plate to control the galvanization applied to the steel plate and a plating amount detection unit for detecting a coating amount attached to the steel plate discharged through the air knife nozzle And a sensor for measuring the amount of deposition of the coating material on the surface of the substrate. The method according to claim 1, The plating control unit A communication interface unit for receiving and outputting various data input and output from the outside, Profile storage means for storing a plating amount profile output from a plating amount detection sensor provided in the plating apparatus, An adhesion amount correction means for calculating a deviation by extracting an adhesion amount corresponding to the portion in the profile storage means and subtracting an average value from the extracted plating adhesion amount and outputting the deviation as a correction amount; A control means for calculating a plating control amount from a plating deposition amount set value inputted from the degree-of-control controlling apparatus and a correction plating deposition amount inputted from the deposition amount correcting means; (W1) from the control calculation unit and calculates a rate of change? D /? W of the interval with respect to the amount of plating on the basis of the set value every time the plating amount set value W1 and the interval D change And correction coefficient calculation means for setting a correction coefficient (Ks) of said control means. 3. The method of claim 2, Wherein the profile storage means stores a plating adhesion amount and an average plating adhesion amount with respect to a distance from a front end of the steel sheet. The method according to claim 2 or 3, The plating deposition amount correcting means (W _temp ) detected by the plating deposition amount detecting means and a distance from the front end of the steel plate when this value is detected, and the average value (W _ave-prev ) of the deposition amount in the profile storing means and the distance partial coating weight (W _temp-prev) extraction, and the coating weight (W _temp-prev) the average partial coating weight (W _ave-prev) partial coating weight the value to an ΔW to the correction amount obtained by subtracting the amount of deposition on the corresponding to (W _temp (W _filtered ), and outputs the amount of adhesion as a feedback amount of the plating adhesion amount to the control means. A method for controlling a plating amount of a plating apparatus for plating a steel sheet produced in a steel cold rolling process, A specification table in which a desired target plating amount W is stored and a setting table in which a control set value is stored are provided and the set values of the target plating amount set value and the plating control amount are calculated using the model formula based on the values extracted from the specification table and the setting table , (W _temp ) detected when the current plating deposit amount is detected, and the detected amount of the plating deposit amount (W _temp ) in the profile of the stored plating deposit amount when this value is detected, wherein the profile of the plating deposit amount attached to the steel sheet discharged from the plating apparatus is stored, (W _temp-prev ) corresponding to the average distance (W _ave-prev ) of the steel plate and the distance from the front end of the steel plate is calculated and the deviation W is corrected as a correction amount to correct the partial adhesion amount W _temp , And outputs it as a feedback amount of, The target plating amount set value is input and a change rate? D /? W of the gap with respect to the plating amount is calculated on the basis of the target plating amount set value by a predetermined model formula, and when the plating amount set value and the gap are changed The correction coefficient Ks is set, And the set value of the plating control amount is modified with the correction factor.