JP3237510B2 - Spray nozzle suitable for preventing quench stain on tin-plated steel sheet and cooling device using this spray nozzle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spray nozzle for cooling a tin layer of a tin-plated steel sheet by reflow treatment in a line for continuously electroplating a steel sheet, and a cooling apparatus using the spray nozzle. About.

[0002]

BACKGROUND OF THE INVENTION Many tinned steel sheets used in cans and other containers are manufactured on continuous electrotinning lines. Usually, a tin-plated steel sheet is required to have an excellent metallic glossy surface. However, a desired metallic glossy surface cannot be obtained with electroplating as it is. In order to obtain a desired metallic glossy surface, a so-called reflow treatment is performed in which the steel sheet after the electro-tin plating is heated, and the tin layer is temporarily melted and then rapidly cooled.

[0003] Usually, the rapid cooling is performed by immersing a steel plate in a water tank called a quench tank. During this quenching, a stain pattern (hereinafter referred to as quench stain) as if sewage adhered and dried is likely to occur on the surface of the tin-plated steel sheet. When quench stain occurs, there is a problem in that the appearance of the tin-plated steel sheet is deteriorated and the commercial value of the tin-plated steel sheet is impaired.

The cause of the quench stain is that when a steel sheet heated to a temperature exceeding the melting point of tin (232 ° C.) is quenched by a quench tank, steam generated at an early stage of the quenching is caught on the surface of the steel sheet, and water and It is considered that the difference in heat transfer with steam causes uneven cooling of the steel sheet, and the steel sheet is not cooled uniformly.

[0005] Various proposals have been made to prevent the occurrence of quench stain. JP-A-54-137440
In the publication, based on the knowledge that the occurrence of quench stain is related to the surface temperature of the steel sheet before entering the quench tank and the water temperature of the quench tank, the surface temperature of the steel sheet before entering the quench tank was measured. Describes a technique for controlling the water temperature of a quench tank to a temperature range in which quench stain is unlikely to occur (hereinafter referred to as prior art 1).

Japanese Patent Publication No. 54-36976 discloses that at a position immediately before entering a quench tank, a cooling liquid is sprayed uniformly over the entire width of the steel sheet from a slit-shaped spray nozzle to cool the steel sheet, and then the steel sheet is immersed in the quench tank. The technique is described (hereinafter referred to as prior art 2).

In the case of the technique described in Prior Art 1,
It is difficult to change the water temperature of the quench tank rapidly,
Even if the water temperature can be changed, the entrainment of steam generated when the steel sheet is immersed in the quench tank is large, and it is difficult to prevent the occurrence of quench stain.

According to the technique described in Prior Art 2,
It is difficult to uniformly cool the steel sheet in the width direction and the front and back surfaces, and it is difficult to stably prevent the occurrence of quench stain.

[0009] In addition to cooling the steel sheet by simply immersing it in the quench tank, cooling water is sprayed on the steel sheet immersed in the quench tank to promote uniform cooling of the steel sheet, thereby preventing the occurrence of quench stain. It has also been done.

For example, JP-A-4-6294 discloses that
In the case of quenching by injecting cooling water into the steel sheet after immersion in the quench tank, paying attention to the fact that quench stain is likely to occur when the steel sheet surface temperature is different between the center and the end in the width direction, A technique is described in which a spray nozzle having a variable flow rate of cooling water in the width direction is used to uniformly cool the steel sheet in the width direction to prevent the occurrence of quench stain. This publication describes a spray nozzle 20 in which a nozzle header 21 having a circular cross section as shown in FIG.

[0011]

The technique described in the prior art 3 is a simple facility, but has a greater quench stain prevention effect than the prior arts 1 and 2. However, quench stain may still occur in this technique.

Furthermore, in recent years, the environment has been changed to be more susceptible to quench stain, such as an increase in the production of thin tin-plated steel sheets or highly alloyed tin-plated steel sheets having a large amount of alloy tin and an increase in line speed. In part, the need to prevent the occurrence of quench stain has increased.

The present invention has been made in view of such circumstances, and in a quench tank of a reflow treatment of a tin plating line, a quench stain generated when cooling water is injected by cooling water to cool a steel sheet. The present invention relates to a simple spray nozzle that can be prevented and a cooling device using the spray nozzle.

[0014]

The present inventor has set forth the situation of the occurrence of quench stain in a cooling device using the spray nozzle shown in FIG. 6 in a quench tank as described in the prior art 3. Was investigated in detail.

As a result, as shown in FIG. 7, at the place where the steel sheet enters the quench tank, the cooling water sprayed from the spray nozzle toward the steel sheet contains steam generated by cooling the steel sheet. , Liquid level 1 on both sides of steel plate
A phenomenon was observed in which the bulge 7 was greatly raised, and when the bulged portion was greatly wavy and fluctuated, it was noticed that quench stain was frequently generated.

Further, since the upper surface of the spray nozzle has an arc shape curved upward, the curved portion becomes an obstacle, and the cooling water injected from the spray nozzle and cooling the steel plate is located behind the spray nozzle, that is, from the steel plate. It cannot flow smoothly in the away direction, and stays in a region near the steel plate intrusion portion of the quench tank in a state where steam after cooling the steel plate is involved. As a result, the water temperature in this region rises, and a large amount of steam is entrained, so that the liquid surface rises greatly, and the rising portion is wavy and fluctuates. As a result, uneven cooling of the steel sheet Was found to be increasing.

From this, the flow state of the cooling water after cooling the steel sheet is involved in the generation of quench stain,
It has been found that to prevent the occurrence of quench stain, it is necessary to improve the flow state of the cooling water containing the steam generated by cooling the steel sheet as described above.

In general, a spray nozzle used in a cooling device for a quench tank is provided with a slit-shaped injection port protruding from a nozzle header having a circular cross section as shown in FIG. It has a structure in which the arranged nozzle tips are provided. In these spray nozzles, there is no recognition of the necessity of improving the flow state of the cooling water after spraying the steel sheet, and no consideration is given to the improvement of the flow state.

The inventor of the present invention has proposed an improvement in the flow state of cooling water containing steam after being sprayed on a steel sheet, that is, a cooling method involving spraying steam from a spray nozzle toward a steel sheet and involving steam generated by cooling the steel sheet. It has been considered that if the water can flow smoothly behind the spray nozzle, it is possible to reduce the swelling and waving of the liquid surface at the steel plate intrusion portion of the quench tank, and to prevent the occurrence of quench stain.

The present invention is based on the above-mentioned idea, and the following are features of the present invention for solving the above-mentioned problems.

A first aspect of the present invention is a spray nozzle for cooling a steel sheet by injecting cooling water in a quench tank of a reflow treatment of a tin plating line, wherein the upper surface of the injection port of the spray nozzle is positioned with respect to the steel sheet. Prevention of quench stain of a tin-plated steel sheet which is a plane inclined by 30 to 75 degrees and wherein the upper surface of the spray nozzle adjacent to the upper surface of the injection port is inclined at an angle greater than the upper surface of the injection port with respect to the steel sheet. Spray nozzle suitable for

According to a second aspect of the present invention, the spray nozzle of the first aspect of the present invention is installed on both sides of a steel plate in a quench tank of a reflow treatment of a tin plating line, and a foam preventing plate wider than the steel plate is provided with the spray nozzle. This is a cooling apparatus for tin-plated steel sheets suitable for preventing quench stain, which is installed so that the upper end of the anti-foaming plate and the upper end of the anti-foaming plate protrude from the liquid surface of the quench tank.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below.

FIG. 1 is a diagram for explaining an embodiment of the first invention. In the figure, reference numeral 2 denotes a spray nozzle, and only one of a pair of spray nozzles provided so as to sandwich the steel plate 9 is shown. Further, the upper nozzle member 13 and the lower nozzle member 14 constituting the spray nozzle 2
Are attached to the nozzle header member 15 by bolts (not shown).

The upper surface of the injection port of the spray nozzle is a plane inclined by 30 to 70 degrees with respect to the steel plate, and the upper surface of the spray nozzle adjacent to the upper surface of the nozzle is the upper surface of the injection port with respect to the steel plate. The plane is inclined at the above angle.
The cooling water pressurized and supplied from the cooling water supply port 16 to the nozzle header 15 is jetted onto the steel plate 9 from a slit formed by the upper nozzle member 13 and the lower nozzle member 14.

FIG. 3 (a) shows a swelling state of the liquid surface near the steel plate intrusion portion of the quench tank when the spray nozzle 2 is disposed so as to sandwich the steel plate and cooling water is sprayed on the steel plate.

The upper surface of the spray nozzle of the spray nozzle 2 is a plane inclined by 30 to 70 degrees with respect to the steel plate, and the upper surface of the spray nozzle adjacent to the upper surface of the spray nozzle has the upper surface of the spray nozzle with respect to the steel plate. Since the plane is inclined at an angle equal to or greater than the upper surface, the cooling water injected toward the steel sheet and entraining the steam generated when cooling the steel sheet flows smoothly behind the spray nozzle. Therefore, the amount of steam caught in the cooling water in the vicinity of the steel plate intrusion portion of the quench tank is reduced, so that the rising of the liquid level due to the cooling water containing the steam in this region is reduced, and the ripples and fluctuations of the rising portion are also reduced. You. As a result, the steel sheet entering the quench tank can be cooled more uniformly, so that the occurrence of quench stain on the steel sheet can be prevented.

FIG. 2 is a diagram for explaining an embodiment of the second invention. Foaming prevention plates 3a and 3b are provided above the spray nozzles 2a and 2b and close to the nozzles. Further, the foam prevention plate 3a,
3b is provided in parallel on the both sides of the steel plate so as to oppose each other in parallel, has a width wider than that of the steel plate, and has an upper end protruding from the liquid surface 17 of the quench tank.

FIG. 3 (b) shows the state of the rise of the cooling water in the vicinity of the steel plate intrusion portion of the quench tank when the cooling water is injected to the steel plate using this apparatus.

The lower end of the foam prevention plate 3 is the spray nozzle 2
, The cooling water injected from the spray nozzle 2 entrains the steam generated by cooling the steel plate, overflows from the upper end of the foam prevention plate 3 provided to protrude from the liquid surface, and Spills out. The injected cooling water can be efficiently used for cooling the steel sheet, and the cooling water containing steam does not stay in the region where the steel sheet sandwiched between the foam prevention plates enters the quench tank. Further, since the lower end of the bubbling prevention plate 3 is located at a position lower than the liquid level of the quench tank and is close to the spray nozzle 2, the cooling water flowing out over the upper end of the bubbling prevention plate 3 causes Even if the liquid level fluctuates outside of this, the influence does not reach the inside of the foam prevention plate 3.

For these reasons, the ripples and fluctuations of the liquid surface in the region sandwiched by the foam preventing plate 3 in which the steel sheet enters the quench tank are suppressed, and the occurrence of quench stain can be prevented.

The upper surface of the injection port of the spray nozzle is
It is necessary that the plane is inclined by 30 to 75 degrees with respect to the steel plate. If the inclination angle (θ) is less than 30 degrees, the swelling of the liquid surface becomes large, so that the swelling of the liquid surface in the width direction becomes non-uniform, and if it exceeds 75 degrees, the steel sheet enters the quench tank. Because the generated steam is difficult to be discharged, transition boiling or film boiling occurs on the steel sheet surface,
In any case, quenching stain is likely to occur.

Further, the upper surface of the spray nozzle adjacent to the upper surface of the injection port of the spray nozzle needs to be a plane inclined at an angle equal to or more than the upper surface of the injection port with respect to the steel plate. When the inclination angle is smaller than the inclination angle of the upper surface of the injection port of the spray nozzle with respect to the steel plate, the swelling of the liquid surface becomes large, so that the swelling of the liquid surface in the width direction becomes non-uniform, and quench stain easily occurs. .
More preferably, the inclination angle with respect to the steel plate is 90 degrees.

The width (L) of the upper surface of the spray nozzle adjacent to the upper surface of the spray port of the spray nozzle is 20 to 1
Desirably, it is 50 mm. The width (L) is 20
If it is less than mm, the cooling water will not easily flow behind the spray nozzle, and quench stain will easily occur. Also,
If it exceeds 150 mm, this effect is saturated, and conversely, an adverse effect occurs due to an increase in the size of the apparatus.

The diameter (H) of the spray nozzle is 5
mm or less. If it exceeds 5 mm, the swelling of the liquid surface becomes large due to the increase of the cooling water injection amount, so that the swelling of the liquid surface in the width direction becomes non-uniform,
Quench stainless easily occurs. Diameter (H) is 3m
m or less is more preferable.

Regarding the depth of the spray nozzle, the distance (D) from the upper surface of the spray nozzle adjacent to the upper surface of the injection port of the spray nozzle to the liquid surface is preferably within 100 mm. If it exceeds 100 mm, it becomes difficult to rapidly cool the steel sheet, and it is difficult to discharge the cooling water containing the generated steam, so that transition boiling or film boiling occurs on the steel sheet surface, and quenching stain occurs in each case. Easier to do.

The distance (d) between the spray nozzle and the steel plate is
It is desirable to be 15 to 30 mm. If it is less than 15 mm, the spray nozzle may come into contact with the steel sheet, and if it is more than 30 mm, the steel sheet is less likely to be rapidly cooled,
Quench stain tends to occur.

The injection direction of the cooling water is -3 with respect to the steel plate.
Preferably, it is 0 to +30 degrees (+ indicates an upward direction from horizontal). When the angle is higher than +30 degrees, the swelling of the liquid surface becomes large. Therefore, the swelling of the liquid surface in the width direction becomes non-uniform. When the angle is lower than -30 degrees, the cooling capacity is reduced, and quench stain tends to occur.

The distance (d ₀ ) between the foam preventing plate and the steel plate is
It is preferable that the distance is 15 to 30 mm, which is substantially equal to the distance between the steel plate and the spray nozzle.

It is necessary that the upper end of the foam prevention plate protrudes above the liquid surface. The height (h) projecting from the liquid surface is preferably not more than half the height at which the overflow of the liquid does not occur. Beyond this height,
Since the steam contained between the foam preventing plates is likely to increase, transition boiling or film boiling occurs on the steel sheet surface, and quenching stain is easily generated in each case.

Since the lower end of the bubbling prevention plate is close to the spray nozzle, most of the injected cooling water passes between the bubbling prevention plates and overflows from the upper portion of the bubbling prevention plate, which is effective in rapidly cooling the steel plate. .

The material of the spray nozzle and the foam preventing plate is not particularly limited.
Commonly used materials can be used.

The apparatus of the present invention can be widely applied to a known apparatus for cooling a steel sheet using a spray nozzle in a quench tank of a reflow process. There is no particular limitation on the method of heating and melting the tin layer in the reflow treatment.

In order to equalize the pressure of the cooling water sprayed from the spray nozzle, a known technique such as a double pipe for the nozzle header or a pressure regulating plate provided between the nozzle header and the slit is applied. It is also possible.

The cooling water jetted from the spray nozzle may be a mixture of gas containing air bubbles in advance and cooling water.

If necessary, the spray nozzle may have a structure in which the flow rate in the width direction is variable.

[0047]

【Example】

(Example 1) A case of performing a cooling method of a reflow process using the spray nozzle described in the embodiment of the first invention will be described with reference to FIG.

In FIG. 4, 1 is a quench tank, 2
a and 2b are spray nozzles arranged with a steel plate interposed therebetween;
Is a pump for circulating and supplying the water in the quench tank to the spray nozzle. Cooling water is supplied to the quench tank 1 from a cooling water supply pipe 5, and excess cooling water overflows from an overflow pipe 6. The water temperature of the quench tank is adjusted to a predetermined water temperature by heating the heating pipe 7 or adjusting the flow rate of the supplied cooling water.
Reference numeral 8 denotes a heating furnace for heating and melting the tin layer.

Steel plate 9 in which tin layer is heated and melted in heating furnace 8
Enters the quench tank 1. After the steel sheet 9 is cooled rapidly by spraying cooling water from the spray nozzles 2a and 2b at the entrance to the quench tank 1, the steel sheet 9 is turned by the roll 10 in the quench tank and then travels outside the quench tank 1. I do. The cooling water sprayed from the spray nozzles 2a and 2b entrains steam generated when cooling the steel plate. The cooling water containing the steam flows through the upper surfaces of the spray nozzles 2a and 2b toward the rear of the spray nozzle (in a direction away from the steel plate). The surface fluctuation is reduced, and the occurrence of quench water can be prevented.

(Embodiment 2) Next, a case of performing rapid cooling in a reflow process using the apparatus described in the second embodiment of the present invention will be described with reference to FIG.

In FIG. 5, in addition to the apparatus shown in FIG. 4, foam preventing plates 3a and 3b are provided above the spray nozzles 2a and 2b in proximity to the spray nozzles. The upper ends of the foam prevention plates 3a and 3b protrude above the liquid surface, and the lower ends thereof are located below the liquid surface. The cooling method of the reflow process in this apparatus can be performed by the same method as that of the first embodiment shown in FIG.

The anti-foaming plates 3a and 3b improve the cooling effect of the steel plate immersed in the quench tank 1, reduce the retention of water in the anti-foaming plate after cooling by entraining steam, and reduce the outside of the anti-foaming plate. The effect of the liquid level fluctuation does not reach the steel sheet intrusion part inside the foam prevention plate, which is effective in preventing the occurrence of quench stain.

[0053]

According to the spray nozzle and the cooling apparatus of the present invention, the quench stain of the tin-plated steel sheet generated when cooling water is injected to cool the steel sheet in the quench tank of the reflow treatment of the tin plating line. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a view for explaining an embodiment of the first invention of the present invention.

FIG. 2 is a diagram for explaining an embodiment of the second invention of the present invention.

FIG. 3 is a diagram for explaining the operation of the device of the present invention.

FIG. 4 is a diagram for explaining a reflow processing method when the apparatus of the first invention of the present invention is used.

FIG. 5 is a diagram for explaining a reflow processing method when the apparatus according to the second invention of the present invention is used.

FIG. 6 is a diagram showing a conventional spray nozzle.

FIG. 7 is a diagram for explaining the operation when a conventional spray nozzle is used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Quench tank 2, 2a, 2b Spray nozzle 3, 3a, 3b Foaming prevention plate 4 Pump 5 Cooling water supply pipe 6 Overflow pipe 7 Heating pipe 8 Heating furnace 9 Steel plate 17 Liquid level 20 Spray nozzle

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-9-263991 (JP, A) JP-A-5-9783 (JP, A) JP-A-8-176885 (JP, A) 48821 (JP, U) JP-A 60-78875 (JP, U) JP-A 2-94257 (JP, U) JP-B 43-26977 (JP, B1) (58) Fields surveyed (Int. Cl. ⁷ , DB name) C25D 5/50 C25D 5/26

Claims (2)

(57) [Claims] 1. A spray nozzle for injecting cooling water to cool a steel sheet in a quench tank of a reflow treatment of a tin plating line, wherein an upper surface of the spray nozzle is 30 to 75 degrees with respect to the steel sheet. A quench stain of a tin-plated steel sheet, wherein the quench stain is a plane that is inclined and an upper surface of the spray nozzle adjacent to an upper surface of the injection port is inclined at an angle equal to or greater than an upper surface of the injection port with respect to the steel plate. Spray nozzle suitable for prevention. 2. The spray nozzle according to claim 1 is installed on both sides of a steel plate in a quench tank of a reflow treatment of a tin plating line, and a foam prevention plate wider than the steel plate is placed above the spray nozzle. A cooling apparatus for a tin-plated steel sheet suitable for preventing quench stain, wherein an upper end of the foam prevention plate is installed so as to protrude from a liquid surface of the quench tank.