JPH0318498Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a device for removing contaminants in a snout in a continuous molten metal plating line.

(Prior art) A steel strip that has been annealed and whose surface has been reduced and purified by passing through an annealing path in a reducing atmosphere is introduced into a plating bath through a snout with its surface unoxidized.
In continuous molten metal plating, in which zinc is deposited on the surface of a steel strip while passing through molten metal (e.g. molten zinc), the surface of the steel strip has a portion surrounded by a snout that is immersed in the surface of the plating bath. A large amount of molten metal adheres to the surface.

However, the molten metal in this part is mixed with iron eluted from the steel strip, and the concentration of iron gradually increases. As described above, if the iron content in the molten metal gradually increases within the snout, the plating layer will fluctuate, leading to a decrease in quality.

In addition, attempts have been made to improve the plating layer by adding an appropriate amount of aluminum to the molten metal, but when aluminum is added, the iron eluted from the steel strip preferentially reacts with the aluminum, forming a solid phase called Fe ₂ Al ₃ . This substance floats to the surface and turns into dross. Further, molten metal evaporated from the bath surface in the area surrounded by the snout adheres to the inner wall of the snout as metal ash, and a portion of the ash falls onto the bath surface inside the snout.

The impurities consisting of the dross and metal ash adhere to the steel strip entering the steel strip, or adhere to the plating surface due to the entrainment phenomenon when entering the steel strip, degrading the quality. In addition, due to the generation of dross, the amount of aluminum in the molten metal decreases, causing fluctuations in the plating layer and hindering the stabilization of quality.

Therefore, a technology was proposed in Japanese Patent Application Laid-Open No. 1983-1981 that was designed to effectively remove the impurities and improve quality and productivity without stopping the continuous molten metal line.
- It was made according to Publication No. 230969.

(Problems to be Solved by the Invention) In this technique, the impurities on the molten metal surface within the snout are sucked together with the molten metal by an electromagnetic pump, and are discharged from the snout.

However, in the above configuration, the structure for attaching the electromagnetic pump to the snout becomes large-scale, and the ease of attachment is poor. In addition, it is necessary to seal the coil part of the pump very tightly and to surround the entire pump with a casing with high sealing performance, which leads to a complicated structure and an increase in the number of parts, resulting in a high price. . Moreover, when performing maintenance and inspection on the electromagnetic pump, it is necessary to lower the bath level of the zinc bath considerably below the position of the electromagnetic pump and remove the electromagnetic pump, making the preparation work before maintenance and inspection of the electromagnetic pump 8 extremely troublesome. becomes. Furthermore, the electromagnetic pump cannot be maintained or inspected during the plating operation because the bath level of the zinc bath must be lowered significantly below the level of the electromagnetic pump.

Therefore, if the electromagnetic pump breaks down during the plating work, there are various problems such as having to stop the electromagnetic pump until periodic inspection of the line.

Further, a mechanical pump may be used instead of the electromagnetic pump, but in a mechanical pump, foreign matter is interposed between the impeller and the casing, which significantly reduces pump performance. Therefore, there are problems such as poor removal efficiency of foreign matter and troublesome maintenance and inspection.

The present invention has been developed in view of the background of the prior art described above, and can simplify the structure and improve the efficiency of removing impurities, as well as facilitate installation and maintenance and inspection, and reduce costs. An object of the present invention is to provide a device for removing contaminants in a snout in a continuous molten metal plating line.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a duct between the internal plating bath surface of the snout which is immersed in the surface of the plating bathtub and the external plating bath surface. The inner and outer openings are provided so as to be submerged under the bath surface, and the inner and outer openings are set at the same height, and the outer opening has a propulsion device fixed at a desired position. The propeller is arranged to be removable.

(Function) In the present invention, when the propeller of the propulsion device, which is disposed in and out of the external opening of the duct, is rotated, its thrust moves the molten metal under the bath surface, including foreign matter inside the snout, into the internal opening. It is drawn into the duct and discharged to the outside of the snout through the external opening to remove foreign matter near the steel strip. Therefore, impurities do not adhere to the surface of the steel strip.

In addition, since the propeller of the propulsion device installed in the external opening of the duct can be taken in and out, maintenance and inspection of the propulsion device and its propeller is extremely easy, and maintenance and inspection can be performed even during plating work. .

Furthermore, since the external opening of the duct submerged below the surface of the plating bath outside the snout and the internal opening of the duct submerged below the surface of the plating bath inside the snout are set at the same height, the surface of the plating bath The immersion depth of the external opening and the immersion depth of the internal opening in the snout are the same, and by looking at the immersion depth of the external opening, it is easy to determine the immersion depth of the internal opening in the snout. can be known. Therefore, when the molten plating is consumed and the plating bath level drops, as long as the plating material is supplied while paying attention to the immersion depth of the external opening, the internal opening in the snout will be lower than the plating bath surface. This prevents the molten plating inside the duct from being pumped out by the propeller of the propulsion device, allowing the explosive gas ( _H2 gas) inside the snout to flow from the internal opening of the duct to the outside. The risk of leakage to the outside through the opening can be effectively avoided.

(Example) FIG. 1 is a longitudinal sectional front view showing an example of the present invention, in which a steel strip 1 is annealed and its surface is purified in an annealing furnace having a reducing atmosphere in a pre-process (not shown).

Next, the steel strip 1 passed through the snout 2 and was introduced into the plating bath surface 4a inside the snout 2 in the molten metal (for example, molten zinc or molten zinc alloy) 4 of the plating bath 3 with its surface unoxidized, and was transferred toward the back of the page. It is then pulled up and led out from the plating bath surface 4b outside the snout 2.

The lower end opening of the snout 2 is submerged in the surface of the molten metal, and a duct 5 that connects the lower part of the internal plating bath surface 4a and the lower part of the outer plating bath surface 4b is provided in the width direction of the steel strip. A pair is provided on each side. Both ducts 5 are made of heat-resistant steel (for example, stainless steel), and are each fixed to the snout 2 via fixing means (not shown) so as to be movable up and down.

One of the ducts 5 has an internal opening 5A that opens under the plating bath surface 4a inside the snout 2, and an external opening 5B that opens under the plating bath surface 4b outside the snout 2. The internal opening 5A and the external opening 5B are set at the same height, so that the depth of the internal opening 5A can be estimated by knowing the depth of the external opening 5B. The depth thereof is approximately 50 mm from the bath surfaces 4a and 4b.

It is said that it is desirable to set the positions of the inner and outer openings 5A and 5B at a depth of approximately 20 mm from the bath surfaces 4a and 4b in order to most effectively remove foreign matter, which will be described later. The depth is set to 50 mm in consideration of the fluctuations in the levels of 4a and 4b.

Reference numeral 5A1 denotes a flow rectifier, which, as shown in FIGS. 2 and 3, is provided at the upper end of the rectangular closed section 5a in the vertical direction, extends upward from the internal opening 5A, and is connected to the bath surface 4.
The steel strip 1 is formed in a U-shape with open portions protruding from a and facing both side surfaces of the steel strip 1. Further, the external opening 5B is provided upward at the upper end of the round closed section 5b in the vertical direction, and is located at the lower part of the square closed section 5a and the round closed section 5b that are inclined in the same direction as the inclination direction of the snout 2. are communicated through a communication portion 5c of a rectangular closed portion.

The propulsion device 6 consists of a rotary drive section 6A formed by a rigid flange motor, and a propeller shaft 6B and a propeller 6C that are driven to rotate in forward and reverse directions by this. In this embodiment, the three-blade propeller 6C is arranged in two stages, upper and lower. Each has a fixed configuration. The propeller shaft 6B is removably fixed to the plating bathtub 3 by a fixing means (not shown).
and a propeller 6C are arranged so as to be removable in and out of the external opening 5B of the duct 5. In addition, the gap between the propeller and the inside of the duct 5 is set to 20 to 30 mm to allow easy insertion and removal. Note that the propeller shaft 6B and the propeller 6C are each made of heat-resistant steel (stainless steel).

Next, the operation of the above configuration will be explained.

When the rotation drive unit 6A of the propulsion device 6 is driven to rotate the propeller shaft 6B and the propeller 6C, for example, in the forward direction, the thrust of the propeller 6C causes the molten metal 4 in the duct 5 to move from the internal opening 5A to the external opening. A flow of arrow A toward 5B occurs.

Therefore, the plating bath surface 4a in the snout surrounded by the snout 2 and the molten metal 4 near the bottom of the bath surface 4a are sucked into the duct 5 from the internal opening 5A, and are introduced into the duct 5 from the external opening 5B. is discharged. Therefore, even if foreign matter is generated on the plating bath surface 4a, it is discharged and removed to the outside of the snout 2 together with the molten metal 4, thereby keeping the inside of the snout 2 clean and preventing the foreign matter from adhering to the steel strip 1. .

Furthermore, even if iron leached from the steel strip 1 mixes into the molten metal 4 surrounded by the snout 2, the iron concentration will not gradually increase only in this part, so fluctuations in the plating layer will not occur. suppressed and stabilizes quality.

Further, one propulsion device 6 (for example, the right side in FIG. 1) is rotated in the forward direction to cause the molten metal 4 in the duct 5 to flow in the direction of arrow A, and the other propulsion device 6 is rotated in the reverse direction to flow the molten metal 4 in the duct 5. By flowing the molten metal 4 in the direction of arrow B, the foreign matter in the snout 2 is pushed to the right, so that the foreign matter can be removed most effectively.
In this case, the periphery of the external opening 5B of the other duct 5 has a cylindrical shape that projects upward from the melting surface 4b and extends downward from the opening surface of the external opening 5B, as shown by the two-dot chain line in FIG. By providing the weir 10, only clean molten metal that does not contain top loss on the melt surface 4b can be introduced into the snout 2.

Further, maintenance and inspection of the propulsion device 6 can be easily carried out by unfastening the propulsion device 6 from the plating tank 3 and then pulling it up.

In the above embodiment, the contaminant removal device is connected to the steel strip 1.
Although one pair is provided on both sides in the width direction, it is of course possible to provide only one pair on one side.

(Effect of the invention) As explained above, according to the invention, the internal opening of the duct is provided below the surface of the plating bath inside the snout which is immersed in the surface of the plating bath, and the plating bath outside the snout is The external opening of the duct is provided below the surface, and the propeller of the propulsion device fixed at a desired position is placed in and out of the external opening, simplifying the structure and improving the efficiency of removing foreign matter. Moreover, the installation and maintenance of the propulsion device is easy, and furthermore, by paying attention to the depth of immersion of the external opening of the duct, explosives in the snout can be easily removed from the internal opening of the duct through the external opening. This has useful effects such as being able to effectively avoid the danger of gas (H ₂ gas) leaking outside.

[Brief explanation of the drawing]

Figures 1 to 3 show one embodiment of the present invention, with Figure 1 being a longitudinal sectional front view, Figure 2 being a front view of the duct, and Figure 3 being a cross-sectional plan view of the main part of Figure 1. . 2... Snout, 3... Plated bathtub, 4... Molten metal, 4a... Plated bath surface in snout, 4b
...Metted bath surface outside the snout, 5...Duct, 5
A... Internal opening, 5 B... External opening, 6...
Propulsion device, 6C...propeller.

Claims (1)

[Scope of utility model registration request] A duct is provided between the internal plating bath surface and the external plating bath surface of the snout that is immersed in the surface of the plating bathtub, and the duct is provided so that its internal opening and external opening are submerged below the bath surface. A snout for a continuous molten metal plating line, characterized in that an internal opening and an external opening are set at the same height, and a propeller of a propulsion device fixed at a desired position is removably disposed in the external opening. Internal contaminant removal device.