JPH07180021A - Method for controlling nozzle gap of plating equipment - Google Patents

Abstract

PURPOSE:To provide a method for controlling a nozzle gap capable of making the coating weight on the front and rear of a sheet uniform in spite of presence of sheet warpage with plating equipment. CONSTITUTION:The actual value of the coating weight on the front and rear is taken in (step 101) and the deviation between the actual value of the coating weight on the front and rear of the steel sheet and the target value of the total adhesion of the front and rear is checked (step 102) with the plating equipment for regulating the coating weight of the steel sheet coated with molten zinc on the surfaces by controlling the pressure of the gas to be blown out of the nozzles and the nozzle gap. In addition, the deviation between the actual value of the coating weight on the front and the actual value of the coating weight on the rear is checked (step 105). The set value of the nozzle gap described above is corrected in accordance with these deviations (step 106).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a nozzle gap in a plating facility for making the amount of plating adhered even when the surface of a steel sheet is plated with hot-dip galvanizing even if the plate is warped. Is.

[0002]

2. Description of the Related Art For example, hot-dip galvanizing is applied to high-grade steel sheets used in automobiles, home electric appliances and the like, and the hot-dip galvanizing line is the final step in the production of high-grade steel sheets. Explaining an example of the hot dip galvanizing line, immediately after the annealed steel plate passes through the hot dip zinc pot, excess hot dip zinc adhering to the steel plate surface is removed by the injection pressure of the nitrogen gas injected from the nozzle, and the target zinc The structure is such that the adhesion amount (thickness) is set. Such a hot dip galvanizing process is also an important process for determining the quality of the product and the manufacturing cost.

The amount of zinc adhered (usually evaluated by the amount of gram of zinc per unit area) is determined by the application and the customer's specifications. Conventionally, the control is based on the injection gas pressure from the nozzle and the nozzle gap. This is done by setting the operation amount. Specifically, the target zinc adhesion amount is received from a host computer (vidicon) from a process computer (hereinafter referred to as "pro computer") which is a lower computer, and this is used as a control target value. A control method is adopted in which the manipulated variable is calculated for each book and the nozzle gas pressure is corrected by the feedback control means based on the actual amount of zinc deposited in the steel sheet.

In controlling the nozzle gap,
The gap setting value for the front surface of the steel plate and the gap setting value for the back surface are the same.

[0005]

However, in the above-mentioned prior art, the control design is made on the assumption that the gap setting value is the front gap setting value = the back gap, that is, the steel sheet passes through the center of the nozzle gap. However, when the steel plate is warped, the gap is partially different, so that the amount of zinc deposited on the front and back becomes non-uniform and the quality of the product deteriorates.

That is, the structure of the molten zinc pot portion of the hot dip galvanizing line is as shown in FIG. 5, and a U-shaped roll 52 is horizontally arranged near the bottom of the molten zinc pot 51 filled with molten zinc. A steel plate 53 is suspended on the.
At the upper part of the molten zinc pot 51, a pair of support rolls 5 for supporting the steel plate exiting the molten zinc pot 51.
No. 4 is provided, and a nozzle 55 for adjusting the zinc coating thickness is provided on the upper part of the No. 4 so as to interpose the steel plate 53.

As shown in FIG. 5, the steel plate 53 enters the molten zinc pot 51 from the direction of the arrow, contacts the roll 52 so as to make a half turn, passes through the support roll 54 between the nozzles 55, and a guide roll (not shown). Is taken out through. At this time, if the steel plate 53 passes between the nozzles 55 while maintaining the flatness, the intervals between the nozzles and the entire surface of the steel plate 53 will be uniform, and the amount of zinc deposited on the front and back surfaces will be uniform.

However, as shown in FIG. 6, when there is a warp in the width direction of the steel sheet, a continuous distance difference occurs between the nozzles on the front and back sides, resulting in a difference in the nozzle gap, resulting in uneven zinc adhesion on the front and back sides. become. It is considered that such plate warpage is caused by the influence of the pressing pressure on the support roll 54 and the like. Conventionally, plate warping has been dealt with by manually adjusting the gap difference by the operator so that the adhered amounts on the front and back sides are the same.

Therefore, an object of the present invention is to provide a nozzle gap control method in a plating facility which can make the amount of plating adhered on both surfaces of a steel plate even if there is warpage.

[0010]

In order to achieve the above object, the present invention relates to a hot-dip galvanized metal by controlling the gas pressure and nozzle gap blown from a nozzle for a steel sheet having hot-dip galvanized metal adhered to its surface. In the plating equipment that adjusts the adhesion amount, check the deviation between the actual adhesion amount on the front and back of the steel sheet and the target value of the total adhesion amount on the front and back, and the deviation between the actual adhesion amount on the front and the actual adhesion amount on the back. The set value of the nozzle gap is corrected based on these deviations.

[0011]

According to the above-mentioned means, the deviation between the actual value of the adhered amount on each of the front and back of the steel sheet and the target value of the total adhered amount on the front and back sides,
Also, the set value of the nozzle gap is determined based on the deviation between the actual adhesion amount values on the front and back sides, and the nozzle gap is corrected. Therefore, even if the plate warps, the amount of plating adhered on the front and back of the steel plate can be made uniform.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a flow chart showing a processing example of a nozzle gap control method in plating equipment according to the present invention. Further, FIG. 2 is a functional explanatory diagram of a zinc adhesion amount control system that achieves the method of the present invention.

As shown in FIG. 2, a proc-con 2 is connected to the vidicon 1 through a communication line. On the other hand, the hot-dip galvanizing equipment includes a hot-dip zinc pot 4 filled with hot-dip zinc (hot-dip galvanized metal) 3, a roll 5 installed in the hot-dip zinc pot 4 for inserting a steel plate 6 into the hot-dip zinc 3, A pair of front and back nozzles 7a, 7b arranged on the upper portion of the molten zinc pot 4 for adjusting the thickness of the molten zinc adhering to the steel plate 6 to a required thickness, and arranged on the upper portion of the nozzles 7a, 7b so as to be movable up and down. The zero spangle device 8 for removing the zinc crystal pattern (spangle pattern) on the steel plate surface, the plurality of rolls 9 for guiding and conveying the steel plate after the zinc adhesion, and the zinc adhesion amount (plating adhesion amount) on the steel plate 6 The zinc adhesion amount meters 10a and 10b to be measured, a speed meter 11 to detect the conveying speed of the steel plate 6, a gas pressure control unit 12 to control the gas pressure of the nozzles 7a and 7b, and a gap between the nozzles 7a and 7b. It is configured to include a respective gap control unit 13 for.

The process controller 2 is a zinc adhesion meter 10a, 10
b and the output signal of the speedometer 11 are taken in, and a predetermined calculation is executed based on this information and the information from the vidicon 1,
The nozzles 7a and 7b, the zero spangle device 8, the gas pressure controller 12 and the gap controller 13 are controlled based on this result. Furthermore, the process control 2 is provided with an input / output device 14 for inputting data, calculation results, setting contents, etc. and displaying them. Further, the process control 2 includes peripheral devices (printer, storage device, etc.) not shown.

The process control 2 has a plurality of control functions and a plurality of calculation functions. The control function includes a feedback control unit 21 and a feedforward control unit 22, and the calculation function includes a preset calculation unit 23 and a learning calculation unit 24. Further, a control target calculation unit 25 is provided to give a target value to each control unit and calculation unit 23.

The preset calculation unit 23 is executed at the timing when the coil welding point reaches the soaking furnace, and the standard gas pressure determination means determines the gas pressure of the nozzles 7a and 7b based on the output signal of the control target calculation unit 25. The gas pressure control unit 12 determines the determined value when passing through the welding point pot (or soaking furnace).
Send to. Further, the nozzle gap is calculated based on this, and the gap controller 13 is controlled. Further, the initial position of the zero spangle device 8 is calculated, and the position of the zero spangle device 8 is controlled based on this.

Further, the feedforward control unit 22 is
Similar to the case of the preset calculation, standard gas pressure determination, nozzle gap calculation, zero device position calculation, etc. are performed to control the gas pressure control unit 12 and the gap control unit 13. .
This process allows the operator to correct the target value itself, and recalculates at the timing when the correction value is entered.

Further, the feedback control unit 21 is activated at the timing when the coil welding point reaches the iron-zinc analyzers (zinc deposit amount meters) 10a, 10b, and absorbs the deviation between the deposit amount target value and the actual value. Specifically, at the time when the coil welding point passes through the zinc adhesion amount meters 10a and 10b installed at a position 130 meters from the nozzle position, the current adhesion amount actual result and the line speed are determined by the 10-m cycle of the plate passing. The correction calculation of the gap (total gap and front and back gap) of the nozzles 7a and 7b is executed so as to reach the target value based on the actual pressure and the like, and the gap control unit 13 is controlled based on this result.

Further, the learning calculation section 24 executes learning calculation. This learning calculation is a process of correcting the nozzle gap calculation parameter using the zinc adhesion amount and the actual value of the nozzle gap to calculate the model parameter in order to improve the preset accuracy for each coil. This model parameter is applied to the feedforward control unit 22 and the preset calculation unit 23 and used for each processing.

Next, the nozzle gap control method according to the present invention will be described with reference to FIG. In the figure,
"S" means a step.

First, the process controller 2 takes in information such as the current actual zinc adhesion amount of the nozzles 7a and 7b (S101),
Based on this, the target zinc adhesion amount, the actual zinc adhesion amount, and the deviation are checked (S102). Then, the total gap correction amount is calculated (S103). Since the actual adhesion value of the total front and back is lower than the target value, the total gap should be widened to increase the adhesion amount. Furthermore, the nozzle 7a,
Calculation for correcting the gap difference between 7b and the steel plate 6 is performed (S104).

This calculation includes front-back adhesion amount difference cumulative counter up processing, front-back adhesion difference pointer up processing, processing for calculating front-back adhesion difference and storing it in a predetermined address of the current value information table, front-back adhesion difference time series. It is composed of a process of totaling data, a process of obtaining a time-series average of front-back adhesion amount difference, and a front-back adhesion amount difference difference check process. In the process of executing this process, a process of fetching the model parameter from the learning calculation unit 24 and outputting the current value information of the nozzle is also performed.

Further, the difference between the actual amount of front adhesion and the actual amount of back adhesion is checked based on the model parameter (S10).
5). At this time, if [actual front adhesion amount-back adhesion amount result ≤ adhesion amount actual front / back difference dead band parameter], the process proceeds to step 107. Thereafter, the front and back gap correction calculation is performed based on the current nozzle value information (S10
6), and outputs the result to the gap controller 13.

Here, the front gap is obtained by [front actual nozzle gap + front / back gap correction amount + front / back gap feedback gain × front / back adhesion amount difference time series average value]. Gap + front-back gap correction amount + front-back gap feedback gain x front-back adhesion amount difference time series average value]. In this case, the average value is corrected based on the deviation of the average value of the front and back adhesion amount actual result data of the last 10 times so that the gap setting value does not change due to the vibration of the steel plate 6.

Then, the pressure correction calculation of the nozzles 7a and 7b is performed (S107). The calculation contents include a gap operating range check process, a front / back gap upper / lower limit clamp process, a pressure parameter correction calculation process, a pressure parameter output process, and the like. The actual value is acquired from the nozzle current information.

Further, front and back gap correction calculation is performed based on the model parameter (S108). Also check the gap operating range. If it is outside the operating range,
The upper and lower limits of the gap are clamped and the pressure correction calculation is performed. After that, the pressure set value is output to the gas pressure control unit 12.

FIG. 3 and FIG. 4 show the results of the above-described control. According to the difference in the adhesion amount as shown in FIG. 3, the gap setting value shows the difference in the adhesion amount as shown in FIG. It is modified so that it is close to zero. As a result, the difference between the front and back adhesion amounts can be reduced, the zinc adhesion amount between the front and back surfaces can be made uniform, and the plating accuracy can be improved.

In the above embodiment, the galvanization is explained, but the present invention is applicable not only to the galvanization but also to the same plating equipment.

[0030]

As is apparent from the above, according to the present invention, the amount of hot-dip galvanized metal is adjusted by controlling the gas pressure blown out from the nozzle and the nozzle gap for the steel sheet having the hot-dip galvanized metal attached to the surface. In the plating equipment, the deviation between the actual adhesion amount on the front and back of the steel sheet and the target value of the total adhesion amount on the front and back, and the deviation between the actual adhesion amount on the front and the actual adhesion amount on the back are checked, and based on these deviations. Since the set value of the nozzle gap is corrected by the above, even if there is a warp of the plate, the amount of adhered plating on the front and back can be made uniform.

[Brief description of drawings]

FIG. 1 is a flowchart showing a processing example of a nozzle gap control method in plating equipment of the present invention.

FIG. 2 is a functional explanatory diagram of a zinc adhesion amount control system that achieves the method of the present invention.

FIG. 3 is a characteristic diagram showing actual results of front and back adhesion amount difference in the present invention.

FIG. 4 is a characteristic diagram showing a gap setting value front / back difference in the present invention.

FIG. 5 is a schematic diagram showing a configuration of a molten zinc pot portion of a hot dip galvanizing line.

FIG. 6 is an explanatory view showing the warp of the steel plate in FIG.

[Explanation of symbols]

 1 Vidicon 2 Procon 3 Molten Zinc 4 Molten Zinc Pot 5 Roll 6 Steel Plate 7a, 7b 8 Zero Spangle Device 9 Rolls 10a, 10b Zinc Adhesion Meter 11 Speedometer 12 Gas Pressure Controller 13 Gap Controller 14 Input / Output Device 21 Feedback Control Part 22 Feedforward control part 23 Preset calculation part 24 Learning calculation part 25 Control target calculation part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masatsugu Market No. 1 Kimitsu, Kimitsu City, Chiba Shin Nippon Steel Co., Ltd. Kimitsu Steel Co., Ltd.

Claims (1)

[Claims] 1. In a plating facility for adjusting the deposition amount of a molten plating metal by controlling a gas pressure and a nozzle gap blown from a nozzle for a steel plate having a molten plating metal deposited on its surface, the actual deposition amount of the steel sheet on the front and back sides. Check the deviation between the value and the target value of the total front and back adhesion amount, and the deviation between the actual adhesion amount on the front and the actual adhesion amount on the back, and correct the set value of the nozzle gap based on these deviations. A method for controlling a nozzle gap in a characteristic plating facility.