JPH06322498A - Method for preventing dross from sticking to strip in hot dip galvanizing equipment - Google Patents

Abstract

PURPOSE:To provide a method for preventing dross from sticking to a strip, in which the stickness of the dross is effectively prevented in a hot dip galvanizing equipment. CONSTITUTION:In the method for preventing the dross from sticking to the product, a U-shaped weir 1 surrounding the strip is arranged in a molten zinc pot and clean molten zinc dipped up from the molten zinc pot is flowed into the place partitioned with this weir 1 to form the molten zinc in the inner part of the weir to the flow 5 in the fixed direction and the dross 7 is rejected from the neighborhood of the strip. By this method, the dross rejecting capacity is large in the simple equipment and the surface contamination caused by the floated dross generated at the time of producing the galvanized steel sheet can effectively be prevented and further, since the structure can be simplified, the maintenance work can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing dross from adhering to strips in hot dip galvanizing equipment.

[0002]

2. Description of the Related Art Conventionally, hot-dip galvanized steel sheets are generally heat-treated in an oxidizing atmosphere to burn off impurities on the original sheet, and then uniformly heated in a reducing atmosphere to anneal them. Is immersed in a molten zinc pot in a state of being clean and activated, and plating is performed.

[0003] Such a method is generally widely used because it is not necessary to activate the surface of the steel sheet by using flux and a large amount of continuously plated steel sheet can be produced.

However, in such a method, since the molten zinc in the molten zinc pot for immersing the steel sheet has a free surface in contact with the atmosphere, it reacts with oxygen to form zinc oxide (dross). To do.

Further, the iron element is released from the surface of the steel sheet in the activated state and forms a compound (dross) with the molten zinc. Part of the dross of these oxides and compounds floats in the molten zinc pot. The floating dross is rolled up when the steel sheet passes, and adheres to the plated surface to impair the surface quality.

As a method of preventing such floating dross from adhering to the steel plate, for example, as shown in FIG. 2, an operating operator 8 scrapes the floating dross 10 with an iron handle ladle 9 and collects and removes it from the molten zinc pot. It was

As another example, JP-A-2-34755.
The technology proposed in Japanese Patent Publication is known. This technique will be described below with reference to FIG.

The above publication discloses that the floating dross is discharged to the outside by installing the screw conveyor 11 shown in FIG. 3 in the molten zinc pot.

[0009]

However, in this method,
When applied to the existing equipment, there is a problem that the molten zinc pot and the equipment around the molten zinc pot must be greatly modified in order to secure a mounting space.

Further, it is difficult to collect dross in one place due to its structure, and molten zinc precipitates and grows on the screw shaft immersed in molten zinc, which requires frequent maintenance. As described above, in the related art, there are many practical constraints such as a small dross discharge capacity, large-scale facility remodeling, and frequent maintenance.

In view of the above-mentioned problems, the present invention provides a method for preventing dross adhesion to a strip, which is compact, has a large collection capacity and does not require major equipment modification, and effectively prevents dross adhesion.

[0012]

DISCLOSURE OF THE INVENTION According to the present invention, a U-shaped weir surrounding a strip is installed in a molten zinc pot, and clean molten zinc pumped from the molten zinc pot to a place partitioned by the weir. Is a method for preventing dross from adhering to the strip in a hot dip galvanizing facility, which is characterized by pouring a unidirectional flow into the molten zinc inside the weir and eliminating dross from the vicinity of the strip to prevent it from adhering to the product. .

[0013]

According to the present invention, a steel plate rising vertically from a molten zinc pot is surrounded by a U-shaped weir having an open side, and a metal pump attached to the outside of the molten zinc pot melts the outside of the weir. Pump up zinc.

The pumped molten zinc is discharged into the weir. This molten zinc creates a unidirectional flow inside the weir, and the floating dross is trapped in the flow and discharged to the outside of the weir.

[0015]

FIG. 1 is a diagram showing an embodiment of the present invention. Reference numeral 1 is a U-shaped weir surrounding the strip, 2 is a metal pump, 3 is a pump suction port, and 4 is a pump discharge port.

The pump suction port 3 is installed at an appropriate depth in the plating tank in which clean molten zinc is present. The molten zinc is pumped up by the metal pump 2, and from the pump discharge port 4, clean zinc whose discharge pressure is changed between 1 to 3 kg / cm ² and discharge speed between ² and 5 m / sec according to operating conditions is discharged. To do.

Since the pump discharge port 4 is installed near the surface layer on the side opposite to the opening side of the weir 1, the molten zinc discharged forms a flow 5. Since this flow 5 is generated only in the surface layer, only the floating dross 7 is trapped and discharged outside the weir without winding up the bottom dross 6. Therefore, the floating dross 7 does not adhere to the strip to be plated.

[0018]

As described above, according to the present invention, it is possible to effectively prevent the plating surface stains due to floating dross generated during the production of hot-dip galvanized steel sheets, and the dross discharging capacity is large with simple equipment. By applying it to equipment, the load on the operator can be reduced, and since the apparatus used in this method can be simplified in structure, it can be maintenance-free equipment, and maintenance work can be reduced.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of the present invention and showing a state in which a flow of clean zinc is formed to eliminate floating dross outside the weir and prevent dross adhesion.

FIG. 2 is a view showing an example of a conventional dross removing method by an operator.

FIG. 3 is a view showing a conventional screw conveyor used for removing dross.

[Explanation of symbols]

 1 U-shaped weir surrounding a strip 2 Metal pump 3 Pump suction port 4 Pump discharge port 5 Clean zinc flow 6 Bottom dross 7 Floating dross 8 Operation operator 9 Iron handle ladle 10 Floating dross 11 Floating dross removal screw conveyor

Claims (1)

[Claims] 1. A molten zinc inside a weir is provided by installing a U-shaped weir surrounding a strip in a molten zinc pot, and pouring clean molten zinc pumped up from the molten zinc pot into a place partitioned by this weir. A method for preventing dross adhesion to strips in hot dip galvanizing equipment, characterized in that a flow in one direction is made to eliminate the dross from the vicinity of the strips to prevent adhesion to products.