JPH07243084A - Equipment for preventing quenching stain of electrolytic tin plated steel sheet - Google Patents

Abstract

PURPOSE:To prevent the occurrence of quenching stain by previously storing the relaions among the difference between the temp. of a steel sheet to be quenched and the saturation temp. of cooling water, the amount of quenching spray injection water, the temp. of the water, and the angle of injection in a control device and performing control so that the difference between the temp. of the steel sheet and the saturation temp. of the cooling water takes a value within the prescribed range. CONSTITUTION:A tin plated steel sheet 4 is fed into a muffle furnace 1 and heated, by which a surface tin layer is melted. The steel sheet is introduced, in this state, into a quenching tank 5 containing a couple of quenching sprays 10, 10a and filled with supplementary cooling water 16, where the steel sheet is sprayed with main cooling water 12 and quenched. At this time, the temp. of the tin plated steel sheet 4 just before cooling is measured by a radiation thermometer 7, and simultaneously, respective temps. of the main cooling water 12 sprayed via the sprays 10, 10a are measured by a cooling water thermometer 8 set in the vicinity of spray headers. Both of these measured signals 19 are inputted to a storage control device 9, and the amount of spray injection, angle, and water temp. are controlled so that the difference between the temp. of the tin plated steel sheet 4 and the saturation temp. of the main cooling water 12 is made constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a manufacturing facility for continuously electroplating a steel sheet, and after the tin layer is subjected to a melting treatment or an alloying treatment, the tin layer on the surface of the electrotin-plated steel sheet is subjected to a reflow treatment. The present invention relates to a quench stain preventive device that is generated during rapid cooling.

[0002]

2. Description of the Related Art Electric tin-plated steel sheets are used for steel sheets for cans and the like. Some steel sheets are electrically tin-plated. Further, on the tin-plated layer, chromium, nickel, iron,
There is also one in which a metal layer such as cobalt is formed and an oxide film is formed on the metal layer.

[0003] Such a steel sheet is usually required to have a glossy plated surface, but if electroplating is simply performed,
Since the desired gloss cannot be obtained, the surface of the tin-plated layer is melted by heating after electroplating with tin and quenching (this quenching is usually called quenching) causes the formation of tin oxide on the surface. And has given the appearance of having a good metallic luster.

During this rapid cooling, a stain pattern (hereinafter referred to as "quench stain") often appears on the plating surface as if water droplets were attached.

As a method for improving such a problem,
As in JP-A-4-350197, the boiling sound of cooling water in a quench tank is used as an output signal with an underwater microphone, and the plate temperature, the spray water amount, the water temperature, and the injection stored in advance are set so that the signal becomes zero. Depending on the angle, the amount of water sprayed,
A quench stain prevention device including a control device that controls the water temperature and the injection angle has been proposed.

[0006]

However, in the device described above (Japanese Patent Laid-Open No. 4-350197), feedback control is performed until the explosion sound in water disappears, and quench stain can be completely prevented. This is not possible, and it is particularly difficult to prevent quench stain when the steel material temperature decreases (for example, during acceleration / deceleration for cutting a tin-plated steel sheet). For this reason, there is a demand for the development of a technique for preventing quench stain and preventing a defective appearance at an industrially low cost.

[0007]

The present invention has been made to solve the above-mentioned problems, and its features are: (1) a device for melting a tin layer of an electro-tinned steel sheet or an alloying device A temperature measuring device for the steel plate before cooling provided on the outlet side, a cooling water temperature measuring device and a cooling water temperature control device, a rotatable quench spray for injecting cooling water onto the steel plate surface, Difference between plate temperature and saturation temperature of cooling water,
The relationship between the spray water volume, water temperature, and spray angle is stored in advance, and the spray water volume, water temperature, and spray angle are controlled so that the difference between the plate temperature and the saturation temperature of the cooling water falls within a certain range. A quench stain prevention device for an electric tinned steel sheet, comprising a memory control device.

(2) A temperature measuring device for the steel plate before cooling, which is provided on the exit side of a tin layer melting device or an alloying treatment device of an electrotin-plated steel plate, a cooling water temperature measuring device, and the cooling water temperature. Control device, a rotatable quench spray for spraying cooling water onto the surface of the steel plate, the difference between the plate temperature and the saturation temperature of the cooling water, the relationship between the spray water amount of the spray, the water temperature, and the spray angle are stored in advance. Then, the spray water amount of the spray, the water temperature, so that the difference between the plate temperature and the saturation temperature of the cooling water is within a certain range,
A quench of an electro-tinned steel sheet, comprising a storage control device for controlling an injection angle, and further comprising a heating control device for controlling a temperature of a melting device and / or an alloying treatment device by a signal of the storage control device. Anti-stain device.

[0009]

[0010]

As a result of various tests, the present inventors have found that the generation of quench stain is caused by non-uniform cooling due to a decrease in heat transfer efficiency, and further, in order to maintain high heat transfer efficiency, Superheat of boiling surface ΔT _SAT = (plate temperature-
(Saturation temperature of water) = (plate temperature + water temperature−boiling point), as shown in FIG. 1, the change in cooling water entry plate temperature is controlled by the quench temperature to keep ΔT _SAT within a certain range (point A to point B). Between the points, more preferably near the point B) and the heat transfer efficiency can be maintained at a high level, resulting in non-uniform cooling and at the time of lowering the temperature of the steel material where quench stain is likely to occur (for example, for cutting a plated steel sheet). The inventors have found that it is possible to prevent the occurrence of quench stain even at the time of acceleration / deceleration or at the time of changing the molten metal amount (alloying amount) at 260 ° C. or less), and have achieved the present invention.

As described above, in order to keep ΔT _SAT within a certain range, the relationships among the steel plate temperature, the cooling water temperature, the water injection amount, the water temperature, and the injection angle are stored in advance, and the plate temperature and the saturation temperature of the cooling water are stored. It was clarified that the amount of water in the nozzle, the water temperature, and the injection angle should be controlled so that the difference between the two is within a certain range. Further, it was clarified that the quench stain can be prevented more effectively by controlling the temperature of the melting device or the alloying treatment device based on the above memory control.

The electrotin-plated steel sheet of the present invention can be applied to any electrotin-plated steel sheet having a tin-plated layer. In addition to the usual electrotin-plated steel sheet, chromium, nickel, etc. are formed on the tin-plated layer. A metal-plated layer of iron, cobalt, or the like, and a tin-plated steel sheet having the metal oxide film thereon can be applied.

The tin layer melting device or alloying treatment device may be any ordinary commercial heating means (electrical heating, combustion heating, etc.), as long as it can be heated above the melting point of tin. From the viewpoint of control accuracy of heating temperature and responsiveness, electric heating (resistance heating, induction heating, etc.) is preferable as the heating means.

As the temperature measuring device for the steel sheet, a non-contact thermometer is preferable because it does not scratch the plating layer. As a temperature measuring method, a jet type (infrared camera, thermoviewer, etc.) which is usually used, Either radiation type or the like may be used.

The temperature measuring device may be installed anywhere on the outlet side of the melting device or alloying treatment device before the steel sheet enters the cooling water, but immediately before the entry, the temperature due to steam generation In order to prevent a decrease in measurement accuracy, it is preferable to attach a suction device or a diffusion device for the generated vapor to prevent the vapor from staying on the measurement surface.

The cooling water temperature measuring device may be measured by an electromotive force difference thermometer (for example, thermocouple type) or the like. It is measured at a plurality of positions in the width direction near the steel plate cooling portion in the quench tank. Although preferable, if the convection of the cooling water is generated near the surface of the steel sheet, the present invention can be sufficiently achieved even if the cooling water is provided at one place instead of a plurality of places.

In a spray for spraying cooling water onto the surface of the steel sheet, the spray tip shape (slit thickness t of the spray header and spray water pressure may be spray water, mist state, or mixed state thereof). .

As shown in FIG. 2, when the spray slit thickness t, the header angle θ, and the steel body and the header distance d are:
As an embodiment, preferably t ≦ 5 mm, θ is ± 40
Within ° (+ (+) is the traveling direction of the steel plate, θ is the reverse direction of the traveling direction of the steel plate), d = 30 to 100 m
However, in order to prevent quench stain more accurately, t ≦ 3 mm, θ is −20 ° or more and + 35 °.
Below (in order to improve heat transfer uniformity, more than 0 ° + 35
It is desirable to suppress the jet water from becoming a vortex near the surface of the steel plate at a temperature of not more than 0 °), and d = 50 to 80 mm. In particular, with respect to the direction of the header, it is preferable that the direction is the same as the traveling direction of the tin-plated steel sheet, as shown in FIG. 2, because the above heat transfer efficiency can be maintained high. If the direction of the header is opposite to the direction of travel of the tin-plated steel sheet, the relative speed of the jet water to the steel sheet rises, and a swirl of jet water tends to be generated near the surface of the steel sheet. It is desirable to lower the cooling water temperature (preferably the water temperature is 80 ° C. or lower) in order to obtain the same cooling efficiency as in the same direction.

As the storage control device for controlling the water amount, water temperature, and injection angle of the nozzle of the present invention, a device for automatic storage control is desirable, but a device for presenting control conditions from storage items may be used. It is more preferable that the control function of this device has a learning function, an Al function, a fuzzy function, a feedforward function, and the like. When controlling the water amount, the water temperature, and the injection angle, the above three factors may be controlled simultaneously, but each factor may be weighted for control.

The quench spray material may be any ordinary cooling spray material.

[0021]

【Example】

Example-1 FIG. 3 is an explanatory diagram of an apparatus according to an example of the present invention, in which a tin-plated steel plate 4 is continuously supplied from the left side, and the steel plate is a muffle furnace 1 via an energizing roll 3. Inside, the temperature is raised by electric heating to melt the tin layer on the surface at the melting point of tin (232 ° C. or higher). In this state, the tin-plated steel sheet discharged from the muffle furnace 1 is guided to the quench tank 5 in which the auxiliary cooling water 16 is filled and the pair of quench sprays 10 and 10a are internally provided. The quench sprays 10, 10a are supplied with the main cooling water 12 in the main cooling water tank 17, the temperature of the steel sheet immediately before the auxiliary cooling water is measured by the radiation thermometer 7, and the vicinity of the headers 18, 18a of the sprays 10, 10a is measured. The temperature of the cooling water jetted by the cooling water thermometer 8 provided in the storage controller 9 is measured based on this measurement signal 19.
The relational expression in (the difference between the plate temperature and the saturation temperature of the cooling water sprayed on the plate, the spray water amount of the main cooling water, the water temperature of the main cooling water, and the relationship shown with the injection angle of the main cooling water to the steel plate ) To control the spray amount of the main cooling water, the temperature of the main cooling water, and the spray angle of the main cooling water to the steel plate, and ΔT _{SAT in} FIG.
Range of points (In the case of electro-tinned steel plate, the steel plate temperature is 25
0 to 300 ° C. is desirable). In this main cooling, the spray injection water amount is stored in the pump P by the storage controller 9
The temperature of the main cooling water 12 is controlled by the main cooling temperature controller 13 in the main cooling water tank 17 based on the information of the storage controller 9, and the main cooling water to the steel plate is controlled. The injection angle is based on the information of the storage control device 9,
The rotary motor 11 is operated to set the quench sprays 10 and 10a at appropriate angles with the rotary shafts 15 and 15a as axes. The sufficiently cooled tin-plated steel sheet 4 is guided to the outside of the quench tank 5 through the sink roll 6.

When the plate temperature rises, in order to suppress the rise of ΔT _SAT , at least one of controlling the spray water temperature of the main cooling water to decrease, increasing the spray water amount and increasing the spray angle is controlled. Then, ΔT _SAT is kept within a certain range and the heat flux is increased to prevent cooling nonuniformity and quench quenching. On the contrary, when the plate temperature decreases, ΔT
_In order to suppress the fall of the _SAT , at least one of increasing the spray water temperature of the main cooling water, decreasing the spray water amount, and decreasing the injection angle is controlled to keep ΔT _SAT within a certain range and to keep the heat flow. Raise the bundle to prevent non-uniform cooling and prevent quench stain. At this time, since the variation of the steel plate temperature due to the control of the spray water temperature of the main cooling, the spray water amount and the spray angle is not large, it is sufficient to keep ΔT _SAT within a certain range, and the quench of the heat transfer efficiency is sufficient. Since it is carried out in a high nucleate boiling state, the steel sheet can be uniformly cooled in the traveling direction and the width direction, and therefore quench stain does not occur.

Embodiment-2 FIG. 4 is also an explanatory view of an embodiment of the present invention. The embodiment of FIG. 2 is further provided with heating control devices 14 and 14a for controlling heating of the muffle furnace 1 and / or the alloying furnace 2 based on the information of the storage control device 9. In such a device, the heating control devices 14 and 14a are the storage control device 9
Since the temperature of tin-plated steel sheet can be controlled with higher accuracy, the accuracy of maintaining ΔT _SAT within a certain range is further improved and is sufficient, and quenching is performed in a nucleate boiling state with high heat transfer efficiency. Therefore, the steel sheet can be uniformly cooled in the traveling direction and the width direction, so that quench stain does not occur.

[0024]

According to the present invention, quench stain, which is caused by non-uniform cooling during quenching of an electrotin-plated steel sheet, can be prevented. As a result, the product value of the electrotin-plated steel sheet is prevented from degrading due to quench stain, and the product yield of the electrotin-plated steel sheet is improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a boiling curve.

FIG. 2 is an explanatory diagram of an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a quench spray.

FIG. 4 is an explanatory diagram of an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Muffle furnace 2 ... Alloying furnace 3 ... Energizing roll 4 ... Tin-plated steel plate 5 ... Quench titanium 6 ... Sink roll 7 ... Radiation thermometer 8 ... Cooling water thermometer 9 ... Memory controller 10, 10a ... Quench spray 11 ... Rotating motor 12 ... Main cooling water 13 ... Main cooling water temperature controller 14,14a ... Heating control device 15,15a ... Rotating shaft 16 ... Auxiliary cooling water 17 ... Main cooling water tank 18,18a ... Header 19 ... Measurement signal 20 … Control signal P… Pump t… Slit thickness θ… Header angle d… Steel plate and header distance

Claims (2)

[Claims] 1. A temperature measuring device for a steel layer before cooling, which is provided on the exit side of a tin layer melting device or an alloying treatment device of an electrotin-plated steel plate, a cooling water temperature measuring device, and the cooling water temperature control device. , A rotatable quench spray for spraying cooling water onto the surface of the steel plate, the difference between the plate temperature and the saturation temperature of the cooling water, the amount of sprayed water of the spray, the water temperature, and the relationship between the spray angle are stored in advance, A quench stain prevention device for an electrotin-plated steel sheet, comprising a storage control device that controls the amount of water sprayed, the water temperature, and the spray angle of the spray so that the difference between the plate temperature and the saturation temperature of the cooling water falls within a certain range. . 2. A temperature measuring device for a steel layer before cooling, which is provided on the exit side of a tin layer melting device or an alloying treatment device of an electrotin-plated steel plate, a cooling water temperature measuring device, and the cooling water temperature control device. , A rotatable quench spray for spraying cooling water onto the surface of the steel plate, the difference between the plate temperature and the saturation temperature of the cooling water, the amount of sprayed water of the spray, the water temperature, and the relationship between the spray angle are stored in advance, The storage controller controls the spray water amount, the water temperature, and the spray angle of the spray so that the difference between the plate temperature and the saturation temperature of the cooling water falls within a certain range. Alternatively, a quench stain preventing device for an electrotin-plated steel sheet, comprising a heating control device for controlling the temperature of the alloying treatment device.