JP2679518B2 - Reflow control method for continuous tin plating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflow control apparatus for a continuous tin plating facility for heating a plate to be continuously fed from a tin plating tank, followed by rapid cooling and reflow treatment.

[0002]

2. Description of the Related Art Tin-plated steel sheets are used as surface-treated steel sheets for food cans and other general cans, and the tin-plated steel sheets are plated by a continuous tin plating facility. In such continuous tin plating equipment, reflow treatment is performed after tin plating on the surface of the steel sheet or tin plating on the Ni plating layer on the surface of the steel sheet. In this reflow treatment, after the surface of a steel sheet is electroplated with tin, the temperature is raised and heated to the melting point of tin by a tin melting device, and thereafter, the steel is permeated into a quench tank and rapidly cooled.

FIG. 7 is a block diagram of a reflow controller for continuous tin plating equipment. The steel plate 1 to be processed is sent from the tin plating tank,
From the first power feeding roll 2 to the induction heating device 5 through the guide rolls 3 and 4, the induction heating device 5 sends the induction heating device 5 to the quench tank 6. Then, the steel sheet 1 to be processed passes between the cooling nozzles 7 in the quench tank 6, and is then sent from the guide roll 8 to the chemical conversion treatment through the second power supply roll 9 and the guide roll 10.

In this case, a power supply is connected to each of the power supply rolls 2 and 9, and a current flows through the steel plate 1 to be processed between the power supply rolls 2 and 9 to perform resistance heating. Therefore, the steel plate 1 to be processed is resistance-heated between the power supply rolls 2 and 9, is induction-heated by the induction heating device 5, and is then rapidly cooled by the quench tank 6.

[0005] Incidentally, the steel sheet 1 to be processed has a portion (hereinafter, referred to as a shape changing portion) in which the shape size, that is, the plate thickness and the plate width are not uniform and the shape size is changed. For this reason, in the resistance heating, the resistance value increases in a portion where the cross-sectional area of the steel sheet 1 to be processed is small, resulting in overheating, and the resistance value decreases in a portion where the cross-sectional area is large, resulting in insufficient heating. For example, as shown in FIG. 8, the thin portion of the steel plate 1 to be processed is overheated, and as shown in FIG. 9, the plate temperature is lowered at the welded portion of the steel plate 1 to be processed. In the case of overheating, the steel sheet 1 to be treated is blackened and melted, and in the case of insufficient heating, a defect called no-melt without gloss due to insufficient tin melting occurs.

Therefore, in order to uniformly control the plate temperature of the steel plate 1 to be treated, as an example thereof, a feedforward (FF) control method in which the set power for the induction heating device 5 is changed is adopted. In this method, a radiation thermometer 11 is arranged upstream of the induction heating device 5 to detect the plate temperature of the steel plate 1 to be processed. Then, the temperature difference between the measured temperature and the target temperature is obtained, and the induction heating device 5 is set so that the temperature difference becomes zero.
The heating temperature of the steel plate 1 to be processed is controlled by changing the set temperature of.

[0007]

However, in such a method, a highly accurate radiation thermometer 11 is required depending on the detection accuracy of the radiation thermometer 11. Also, it is very difficult to match the measured temperature and the target temperature to make the temperature difference zero.
The current situation is that control is performed with a temperature difference.

Therefore, an object of the present invention is to provide a reflow control method for a continuous tin plating equipment capable of stably heating a plate to be processed without causing overheating and underheating of the plate to be processed.

[0009]

SUMMARY OF THE INVENTION The present invention is a continuous tin for resistance-heating and induction-heating a plate to be continuously fed from a tin plating tank, and then quenching the plate. In the reflow process of the plating equipment, the plate temperature of the plate to be processed before induction heating is measured, and the moving average value of this plate temperature is obtained. Then, this moving average value is set as the target temperature of the feedforward control. For this target temperature, a dead zone for the feedforward control operation of the induction heating device is provided. Thus, the feedforward control operation is performed when the plate temperature is continuously out of the dead zone on the plate to be processed for a predetermined length or longer. As a result, the plate to be processed is stably heated without being overheated or insufficiently heated.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. The same parts as those in FIG. 7 are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 is a configuration diagram of continuous tin plating equipment to which a reflow control method for continuous tin plating equipment is applied. A resistance heating control device 20 is connected to each of the power feeding rolls 2 and 9, and an induction heating control device 21 is connected to the induction heating device 5. Further, a power setting device 22 is provided, the resistance heating control device 20 is connected to the power setting device 22 via an adder 23, and the induction heating control device 21 is connected to the resistance setting control device 21 via an adder 24. The power setting device 22 is the resistance heating control device 2
0 and the induction heating control device 21 for each power setting signal P
It has a function of transmitting a and Pb.

On the other hand, a temperature feedback (FB) controller 25 and a temperature feedforward controller 26 are connected to the radiation thermometer 11. The temperature feedback control device 25 takes in the plate temperature signal from the radiation thermometer 11, finds the temperature difference between this plate temperature and the target temperature of the feedback control, and adds the feedback control signal Sa that makes this temperature difference zero to the adder 23. It has the function of sending to.

The temperature feedforward controller 26 is also provided.
Has a function of fetching the plate temperature signal from the radiation thermometer 11 at a predetermined sampling period, obtaining a moving average value of these plate temperatures, and setting this as a target temperature for feedforward control. For example, the plate temperature data is x1, x2, ...
If xn, moving average values (target temperatures) A1, A2, ... Are obtained from 175 pieces of plate temperature data. For example, A1 = (x1, x2, ... x175) / 175 A2 = (x2, x3, ... x176) / 175.

The temperature feedforward controller 26 is also provided.
Has a function of providing a dead zone H of the feedforward control operation with respect to the target temperatures A1, A2 .... The dead zone H is a temperature range in which the upper limit temperature Hh and the lower limit temperature Hl are set for the target temperatures A1, A2 .... That is, Hl ≦ A1 ≦ Hh is set.

The temperature feedforward controller 26 is also provided.
Has a function of performing a feedforward control operation for the induction heating control device 21 when the plate temperature of the steel plate 1 to be processed is outside the dead zone H and this state is continued even if the steel plate 1 to be processed moves by several mm. doing. Next, the operation of the apparatus configured as described above will be described.

The steel plate 1 to be treated is sent from the tin plating tank and
From the power feeding roll 2 to the induction heating device 5 through the respective guide rolls 3 and 4, the induction heating device 5 sends the induction heating device 5 to the quench tank 6. Then, the steel sheet 1 to be processed passes between the cooling nozzles 7 in the quench tank 6, and is then sent from the guide roll 8 to the chemical conversion treatment through the second power supply roll 9 and the guide roll 10.

At this time, electric power is supplied to the power feeding rolls 2 and 9 by the resistance heating control device 20, and the steel plate 1 to be treated between the power feeding rolls 2 and 9 is resistance-heated.
At the same time, the induction heating device 5 is operated by the induction heating control device 21, and the steel sheet 1 to be processed is induction heated.

In this state, the radiation thermometer 11 detects the plate temperature of the steel plate 1 to be treated before entering the induction heating device 5, and outputs the plate temperature signal. This plate temperature signal is supplied to the temperature feedback controller 25 and the temperature feedforward controller 2.
Sent to 6.

Of these, the temperature feedback control device 2
Reference numeral 5 denotes a feedback control signal Sa which receives a plate temperature signal from the radiation thermometer 11 and obtains a temperature difference between this plate temperature and a target temperature for feedback control, and makes this temperature difference zero.
To the adder 23. Therefore, the resistance heating control device 20 uses the temperature control signal Ta and the feedback control signal Sa.
When the control signal is added, the amount of electric power supplied to each of the power feeding rolls 2 and 9 is controlled according to the control signal.

On the other hand, the temperature feedforward controller 2
As shown in FIG. 2, 6 retrieves each plate temperature signal and sequentially obtains the moving average values A1, A2 ... From the 175 pieces of plate temperature data x1, x2 ,.

A1 = (x1, x2, ... X175) / 175 A2 = (x2, x3, ... X176) / 175 Then, the moving average values A1, A2 ... Are set as the target temperature of the feedforward control.

Next, the temperature feedforward controller 26
As shown in FIG. 3, a dead zone H having an upper limit temperature Hh and a lower limit temperature Hl of ± several degrees Celsius, for example ± 3 ° C., is provided with respect to the target temperature A1.

In this way, the temperature feedforward controller 26 sequentially takes in the plate temperature data and obtains the temperature difference between the target temperature A1 and the plate temperature data x176, for example. If the temperature difference is within the dead zone H, the temperature feedforward controller 26 stops its operation.

On the other hand, as shown in FIG. 4, plate temperature data x17
When 6 is outside the dead zone H, and this state continues even if the steel sheet 1 to be processed moves by several mm, for example, 800 mm, the temperature feedforward control device 26 performs the feedforward control operation. That is, the temperature feedforward control device 26 obtains the temperature difference between the plate temperature and the target temperature A1 of the feedforward control, and sends the feedforward control signal Sb that makes the temperature difference zero to the adder 24.

The induction heating controller 21 controls the temperature control signal Tb.
And the feedforward control signal Sb are added, and the amount of electric power supplied to the induction heating device 5 is controlled according to the control signal.

Therefore, in the temperature feedforward control device 26, the plate temperature change in the length direction of the steel plate 1 to be processed is shown in FIG.
The feedforward control is not executed when the temperature gradually rises and decreases as shown in FIG. 6, and the feedforward control is executed when the temperature rapidly increases and decreases (Q and P portions) as shown in FIG. As a result, the plate temperature of the steel plate 1 to be processed is made substantially uniform in the length direction.

As described above, in the above-described embodiment, the moving temperature average value of the plate temperature of the steel sheet 1 to be processed is obtained as the target temperature,
A dead zone is provided for this target temperature, and the plate temperature of the steel sheet 1 to be treated is outside the dead zone H, and this state is the steel sheet 1 to be treated.
Since the feedforward control for the induction heating device 5 is added when the movement continues for several mm, the feedforward control of the induction heating device 5 is detected by detecting the rapid change in the plate temperature of the steel plate 1 to be treated. It is possible to eliminate overheating and insufficient heating in the shape-changed portion of the steel sheet 1 to be treated, and to reduce blackening and melting loss of the steel sheet 1 to be treated due to overheating, and to reduce the occurrence of no melt due to insufficient heating, and to stably treat the steel sheet to be treated. 1 can be heated.

The present invention is not limited to the above-mentioned embodiment, and may be modified within the scope of the invention. For example, when setting the target temperature, 175 pieces of plate temperature data were used, but the number of pieces of data is not limited to this.
Further, the temperature range of the dead zone H and the distance at which the plate temperature is outside the dead zone H may be set arbitrarily.

[0029]

As described above in detail, according to the present invention, it is possible to provide a reflow control method for a continuous tin plating equipment capable of stably heating a plate to be processed without causing overheating or insufficient heating of the plate to be processed. .

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a continuous tin plating facility to which a reflow control method for a continuous tin plating facility according to the present invention is applied.

FIG. 2 is a diagram showing setting of a target temperature in the same method.

FIG. 3 is a schematic diagram showing a dead zone in the same method.

FIG. 4 is a diagram showing additional timing of feedforward control in the same method.

FIG. 5 is a diagram showing a change in plate temperature when the feedforward control is not performed by the same method.

FIG. 6 is a diagram showing changes in plate temperature when feedforward control is performed by the same method.

FIG. 7 is a configuration diagram of a conventional continuous tin plating facility.

FIG. 8 is a diagram showing a heating temperature change in a thin portion of a steel plate to be treated.

FIG. 9 is a diagram showing a heating temperature change in a welded portion of a steel sheet to be treated.

[Explanation of reference numerals] 1 ... Steel plate to be treated, 2, 9 ... Power supply roll, 5 ... Induction heating device, 6 ... Quenching tank, 11 ... Radiation thermometer, 20 ...
Resistance heating control device, 21 ... Induction heating control device, 22 ... Power setting device, 25 ... Temperature feedback control device, 26
… Temperature feedforward controller.

Claims (1)

(57) [Claims] 1. A reflow control device for a continuous tin plating facility, wherein a plate to be treated continuously sent from a tin plating tank is resistance-heated and induction-heated, and then the plate to be treated is rapidly cooled for reflow treatment. In, the plate temperature of the plate to be processed before induction heating is measured to obtain a moving average value, and this moving average value is set as a target temperature of feedforward control for the induction heating, and The continuous tin plating is characterized in that a dead zone for feedforward control operation is provided, the plate temperature is outside the dead zone, and the feedforward control operation is performed when the plate temperature appears on the plate to be processed for a predetermined length or more. Equipment reflow control method.