JP2743774B2 - Continuous hot metal plating method for striped striped steel sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently and continuously hot-dip plating a strip-shaped steel sheet having irregularities on its surface.

[0002]

2. Description of the Related Art A steel plate having a continuous or discontinuous striped or staggered unevenness on its surface (hereinafter referred to as a striped steel plate, sometimes referred to as an anti-slip steel plate) is coated with Zn plating or a Zn-Al alloy. As a method of applying hot-dip metal plating such as plating or Al plating, the striped steel sheet is cut into an appropriate length or processed into a molded product, and then pickled, washed with water, and subjected to flux treatment. A batch method of immersing in a hot-dip metal plating bath by a method called soaking is adopted. This is because if a strip-shaped striped steel sheet with irregularities on its surface (hereinafter referred to as a striped steel strip) is to be subjected to continuous hot-dip metal plating in the same procedure as a normal flat steel strip, it will be applied to a plating bath roll or other in-line roll A flaw caused by the unevenness of the striped steel strip enters, which causes product flaws and also causes plating unevenness, along the convex direction of the striped steel strip surface at the gas wiping part to adjust the amount of plating adhesion Splash occurs, Zn adheres to the nozzle slit portion, and wiping becomes unstable. This is because the gas blown at high speed becomes turbulent due to the unevenness of the surface of the striped steel strip, and the molten metal The difference in heat absorption in the annealing furnace caused by the unevenness of the surface of the striped steel strip, which is considered to be blown away, causes shape distortion in the steel strip, and insufficient reduction (activation) Shortage) Various problems, for example, it is difficult to make the coating weight uniform over the entire uneven portion of the surface of the striped steel strip with normal gas wiping pressure, and a uniform coating weight cannot be obtained. Is caused. Due to such circumstances, continuous hot-dip metal plating of striped steel strip has not been put to practical use, and as described above, it is actually complicated and requires labor and depends on a batch method with low productivity. .

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object the continuous use of the striped steel strip without causing the above-described problems. To provide a method capable of hot-dip metal plating.

[0004]

Means for Solving the Problems The constitution of the continuous hot-dip metal plating method according to the present invention which can solve the above problems is as follows.
After the striped steel strip having irregularities on its surface is pickled, annealing temperature: 450 to 850 ° C. Steel strip tension in the annealing furnace: 0.3 to 2.0 kg / mm ² Steel strip tension in the plating line: 0. 3 to 3.0 kg / mm
⁽²⁾ Gas pressure for wiping molten metal: 0.02 to 1.5 kg /
The gist is that the continuous hot-dip metal plating is performed under the condition satisfying the requirement of cm ² . The bath composition of the hot-dip metal plating used here is Zn / Al = (100
To 0) / (0 to 100), and the preferred plating bath temperature in this case is in the range of 400 to 700 ° C.

[0005]

Operation and Examples Hereinafter, the configuration, operation and effects of the present invention will be specifically described with reference to the history of experiments. In the present invention,
The surface is stripped by hot rolling or further cold rolling, using a striped steel strip as shown in FIG. 1 for example, and the oxide scale adhering to the surface is pickled and removed using hydrochloric acid, sulfuric acid, etc. It is sent to reduce (activate) the surface and raise the temperature to a temperature suitable for hot-dip metal plating, then immersed in a hot-dip metal bath and adjusted the amount of coating by gas wiping, then alloyed if necessary. The plating process is continuously performed by cooling after passing through a heating furnace for processing or the like.

It is preferable that the above-mentioned pickling treatment and annealing be continuously carried out online in connection with the upstream side of the hot-dip metal plating line. However, pickling, annealing and the like are carried out in a separate line, and a heating equipment is provided. Of course, it is also possible to carry out continuous plating through a plated line. Hereinafter, the reason why the annealing temperature, the tension, the wiping gas pressure, and the like are determined in the present invention will be described in detail.

Annealing temperature: 450 to 850 ° C. The striped steel strip after pickling is heated to burn and remove oil and dirt, and to reduce and activate the surface. Further, the temperature is raised to a temperature suitable for hot metal plating. The annealing temperature is 450 to 850 in order to sufficiently clean and activate the surface without causing deformation due to unevenness of the surface of the striped steel strip and to achieve uniform plating adhesion. Must be set in the range of ° C. When the temperature at this time is lower than 450 ° C., plating unevenness tends to occur due to insufficient activation of the surface and insufficient temperature as a hot-dip metal plating material,
It becomes difficult to obtain a uniform plated product. On the other hand, when the temperature is higher than 850 ° C., the flatness is lowered due to the deformation due to the difference in heat capacity due to the surface unevenness of the striped steel strip, and a correction process after the plating process is required.

When this annealing is performed in a non-oxidizing furnace (NOF), the optimum temperature slightly varies depending on the air-fuel ratio of the atmospheric gas. When the air-fuel ratio is 0.90 or less, the annealing temperature is 4 ° C.
When the air-fuel ratio is 50 to 850 ° C and the air-fuel ratio is more than 0.90 and 0.98 or less, the annealing temperature is preferably 500 to 800 ° C. A more preferable range of the annealing temperature is 500 to 800 ° C. As the heating, any of a direct fire system and an indirect heating system can be adopted. If the air-fuel ratio exceeds 0.98, poor plating is likely to occur due to insufficient activation.
It is better to keep it to 98 or less. Table 1 shows the results of examining the effects of various changes in the air-fuel ratio on the plating state and the flatness of the striped steel strip when annealing is performed using a non-oxidizing furnace. 450 to 85
It can be seen that if the temperature is set to 0 ° C., more preferably in the range of 500 to 800 ° C., a good plating adhesion state can be secured without lowering the flatness of the striped steel strip.

[0009]

[Table 1]

[0010] Steel strip tension in the annealing furnace: 0.3 to 2.0 kg / mm ² Steel strip tension in the plating line: 0.3 to 3.0 kg / mm
^{(2) The} tension of the steel strip in the annealing furnace is important for ensuring a stable threading state without causing a shape change such as a width reduction of the striped steel strip or meandering in the running direction. The tension is a stable plating state without causing any flaws on the guide rolls due to the unevenness of the striped steel strip (and, consequently, scratches on the striped steel strip due to the transfer of the flaws) and without meandering the striped steel strip. In order to satisfy these requirements, the steel strip tension in the annealing furnace is 0.3 to
2.0kg / mm ² , steel strip tension in plating line is 0.3
Ｋｇ3.0 kg / mm ² .

Incidentally, Table 2 shows the results of examination of the occurrence of roll flaws and meandering when the tension of the steel strip in the annealing furnace and the plating line was variously changed. It can be seen that meandering of the striped steel strip occurs, making it difficult to obtain a stable running state. On the other hand, if the strip tension is too large, roll flaws are generated, and the quality as a plated product is deteriorated. As is clear from Table 2, the preferable ranges of the steel strip tension in the annealing furnace and the steel strip tension in the plating line are slightly different, but most of them overlap.

[0012]

[Table 2]

The wiping gas pressure: 0.02 to 1.5 kg / cm ^{2 The} wiping gas pressure removes excess molten metal adhering to the surface of the striped steel strip from the plating bath to reduce the amount of plating adhesion. If the gas pressure is insufficient, it is not possible to sufficiently remove excess molten metal adhering to the surface of the striped steel band, especially at the corners of the recess, and the amount of plating applied is uneven. become. On the other hand, if the wiping gas pressure is too high,
Excessive removal of the molten metal attached to the surface of the striped steel band, especially on the top surface of the convex part, causes unevenness in the amount of plating applied.
The droplets not only adhere to the related equipment but also adhere to the surface of the striped steel strip to deteriorate the product appearance.

However, when the wiping gas pressure is set to 0.0
^{2 to} 1.5 kg / cm ² , more preferably 0.05 to
If it is set within the range of 1.2 kg / cm ^2, a uniform and beautiful plated product can be obtained without the above-mentioned difficulties. In addition, the nozzle slit interval of the wiping gas cannot be uniformly defined because it varies depending on the gas pressure, the temperature and viscosity of the plating bath, and the like. However, the preferred nozzle slit interval when the above-mentioned preferred gas pressure is adopted is , 0.5 to 1.5 mm, more preferably 0.6 to
The range is 1.2 mm. It is to be noted that the amount of plating is generally controlled on the basis of the amount of deposition on the plane portion.

Table 3 shows a molten Zn bath (temperature: 46
(0 ° C.), the plating is carried out by immersing the striped steel strip, the nozzle slit interval is set to 0.8 mm and 1.0 m.
This shows the results of examining the plating uniformity and the state of splash generation when the wiping gas pressure was changed variously while the wiping gas pressure was set to m. 02-1.5
kg / cm ² , more preferably 0.05 to 1.2 kg /
It can be seen that when the thickness is set in the range of cm ² , excellent plating uniformity can be ensured without generating splash.

[0016]

[Table 3]

Although the present invention can be applied to various types of hot-dip metal plating, the most commonly used metal is Zn, which has a low melting point and an excellent effect of improving corrosion resistance to steel.
And Al and their alloys, where Zn / Al =
(100-0) / (0-100) weight ratio can be widely used, and when these are used, the preferable plating bath temperature is in the range of 400-700 ° C.

The guide rolls disposed on each line are generally made of cast steel or steel, and the surface thereof is sprayed with an appropriate metal material as needed to improve wear resistance. It is also effective to apply a rubber lining having a hardness of about Hs 50 to 110 to more reliably prevent scratches and the like. In order to make the plating process continuous, it is necessary to weld at the head and tail of the striped steel strip. For this purpose, for example, a service tail is provided downstream of the pickling line and a narrow wrap welder is used. Welding may be used to achieve continuity.

[0019]

The present invention is constructed as described above. Conventionally, it is used as a cut plate or a molded product by "pickling-water-flux-flux processing-immersion in a molten metal plating bath-extra plating metal cutting-cooling". ) Can be continuously processed by a complicated procedure such as that described above, and a striped steel strip of uniform and stable quality can be efficiently manufactured with excellent productivity by setting appropriate conditions.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a striped steel plate used in an example.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masafumi Shimizu 1 Kanazawa-cho, Kakogawa-shi, Hyogo Kobe Steel, Ltd. Kakogawa Works (56) References JP-A-57-114647 (JP, A) JP-A-56 -84451 (JP, A) JP-A-4-362167 (JP, A) JP-A-3-36253 (JP, A)

Claims (3)

(57) [Claims] After the strip- like striped steel sheet is pickled, annealing temperature: 450 to 850 ° C. Steel strip tension in an annealing furnace: 0.3 to 2.0 kg / mm ² Steel strip tension in a plating line: 0.1 to 2.0 kg / mm ² 3 to 3.0 kg / mm
⁽²⁾ Gas pressure for wiping molten metal: 0.02 to 1.5 kg /
A continuous hot-dip metal plating method for band-shaped striped steel sheets, wherein continuous hot-dip metal plating is performed under conditions satisfying the requirement of cm ² . 2. The composition of a hot-dip metal plating bath is Zn / Al =
The method according to claim 1, wherein (100-0) / (0-100). 3. The temperature of the hot-dip metal plating bath is 400 to 70.
3. The method according to claim 2, wherein the temperature is 0 ° C.