JPS6314848A - Method for coating material onto steel sheet - Google Patents

Abstract

PURPOSE:To easily produce an Al-plated extra-thin steel sheet by applying ultrasonic oscillation to a hot dipping metal and subjecting the steel sheet traveling in a nonoxidizing atmosphere to spray deposition. CONSTITUTION:The steel sheet 1 is heated to >=150 deg.C and below the m.p. of the hot dipping metal (Al) and is run in a heating zone 3 in a nonoxidizing or reducing atmosphere box 2. The hot dipping metal 6 is introduced from a thermal spraying tank 4 into a molten metal storage vessel 5 and is oscillated by an ultrasonic oscillator 7, by which the molten metal is sprayed from spray holes 5a onto the surfaces of the steel sheet 1 and is deposited thereto. The molten metal in the vessel 5 is maintained at a constant level during this time and the top end face of the oscillator 7 is formed to a rough surface having recesses or ruggedness. The steel sheet 1 is then rolled at about 0.5-30% draft by press rolls 8, by which the roughness of the coated surfaces is adjusted and the coating adhesiveness is improved. The production of the Al-plated thin steel sheet which is difficult-to-produce is thereby facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of coating a steel plate with a molten plating metal.

(Prior art) Steel sheets coated with metals with a lower melting point than iron, such as metals such as AX, Sn, Zn, and Pb, and alloys containing these as main components, are used for automobiles, cans, electrical equipment, etc. Widely used as a material.

Manufacturing methods for these coated steel plates include immersion plating, which involves dipping the steel plate into molten plated metal and pulling it up;
Other methods include electroplating methods and vapor deposition methods.

The immersion plating method is widely used as a method of plating a steel plate with a metal having a low melting point, and has the advantages of high productivity and low cost compared to other methods such as electroplating.

(Problems to be Solved by the Invention) However, the immersion plating method requires a large amount of molten metal compared to the amount of steel plate processed, and it does not form an alloy layer at the interface between the metal and the steel plate that deteriorates plating adhesion. This also causes υ dross and large metal loss.
There are drawbacks such as difficulty in controlling the amount of adhesion.

Furthermore, it is difficult to perform single-sided plating, and the baking of the paint film cannot be applied to hardenable high-strength steel sheets, or Af
In the case of metals with a relatively high melting point, such as metals, the shape of the steel sheet deteriorates, so there are various limitations such as the inability to apply to ultra-thin steel sheets with a thickness of about 0.4 mm or less.

In the case of electroplating, many of the drawbacks of immersion plating mentioned above are solved, but in addition to the difficulty of plating electrically neutral metals such as A2, there are other problems such as high equipment costs and running costs. It has its drawbacks.

Furthermore, methods such as thermal spraying or vapor deposition are not suitable as mass production techniques due to productivity or equipment costs.
It is only used for processing relatively small quantities.

In order to eliminate the drawbacks of these metal coating methods, many studies and proposals have been made in the past. For example, JP-A-57
Publication No. 58987 discloses a method and apparatus for producing a thermally sprayed clad steel plate, including a method in which a thermally sprayed metal plate having approximately the same width as the steel plate is used as an electrode, continuously supplied to a thermal spraying machine, and thermally sprayed onto the surface of a traveling steel plate; Or, JP-A-59-6735
Publication No. 7 proposes a method of coating a steel plate with metal by depositing molten metal onto a traveling steel plate through a nozzle.

In the case of JP-A-57-58987, an attempt was made to improve production efficiency by making the sprayed metal into a wide strip, but in principle, the conventional wire arc type spray gun could be
It is not much different from having multiple coils arranged in the width direction. Therefore, the thermal sprayed metal has the disadvantage that it tends to cause uneven adhesion due to its non-uniform and coarse particle size, and when the amount of adhesion is small, it is difficult to produce a uniformly coated steel sheet.

Similarly, in the case of JP-A-59-67357, problems such as clogging occur when the slit width of the nozzle is made small or a porous nozzle is used in order to obtain a homogeneous coated steel plate.
If the slit width is increased to avoid this, the plating will become too thick, or the surface tension of the molten metal will be large, resulting in significant uneven adhesion when the steel plate is run at high speed. There are many problems in practical application.

(Means to Solve the Problem) The present inventors focused on the atomization phenomenon of liquids such as water caused by ultrasonic vibration, and conducted intensive studies on a method of atomizing molten metal such as aluminum and depositing it on a steel plate. However, we have completed a completely new metal coating method for steel sheets that eliminates the various drawbacks seen in conventional immersion plating.

That is, the present invention arranges a hot-dip plated metal storage container in a non-oxidizing or reducing atmosphere and close to a traveling steel plate, and applies ultrasonic vibration to the hot-dip plated metal in the container. This is a method for metal coating a steel plate, characterized in that the hot-dip plating metal is sprayed onto the surface of the steel plate to deposit it.

The method of the present invention will be described in detail below.

FIG. 1 is a diagram illustrating the basic line configuration of the method of the present invention.

Heating zone 3 in non-oxidizing or reducing atmosphere box 2
The molten plated metal 6 introduced from the thermal spray tank 4 into the molten metal storage container 5 is applied to the heated steel plate 1 using an ultrasonic vibrator 7.
By applying vibration, the sprayed material is deposited on the surface of the steel plate through the spray holes 5a, and then rolled by the heating roll 8 to adjust the surface.

The steel type of the steel plate used in the present invention is not limited to hot rolled steel plates such as rimmed steel, aluminum killed steel, and silicon killed steel, as-cold rolled steel plates, and annealed steel plates.

It is more effective to heat the steel plate with a heating zone before applying the molten metal to the steel plate. There are two purposes: one is to improve the cleanliness of the steel sheet surface, or surface modification such as surface activation by reducing the oxide film, and the other is to appropriately control the temperature of the steel sheet during adhesion. This improves coating adhesion.

From this point of view, the gas atmosphere in the atmospheric gas box 2 is a non-oxidizing, preferably reducing gas atmosphere. In addition, the heating temperature of the steel plate is 150° at the time of adhesion.
It is desirable to control the temperature to be above C and below the melting point of the plated metal.If the steel plate temperature at the time of deposition is below 150℃, the chemical reaction between the plated metal and the steel plate surface will be small.
Coating adhesion is poor, and when the temperature exceeds the melting point of the plated metal, rationalization progresses, which not only deteriorates adhesion but also deteriorates the shape of thin steel plates.

Here, as a method for depositing molten metal on a steel plate, the present invention utilizes ultrasonic vibration and has an important component of spraying molten metal onto the steel plate from a spray hole provided in a molten metal storage container. be.

The method of spraying molten metal is basically the same whether it is above or below the steel plate, and the tip of the ultrasonic sensor is brought close to the spray hole and immersed in the molten metal. The longitudinal frequency and amplitude of the ultrasonic vibrator and the distance j from the tip of the ultrasonic vibrator in a stationary state to the liquid surface greatly affect the size and amount of atomized particles. The larger the frequency and amplitude and the smaller the distance l, the smaller the atomized particles tend to be.

Therefore, in order to apply a uniform coating with a small amount of coating, it is desirable to increase the frequency and amplitude and make the distance 1 small.On the other hand, when the amount of coating is large, the uniformity of the coating is From the viewpoint of emphasizing efficiency because it is easy to secure, it is not necessarily necessary to sufficiently atomize it, and in short, it is sufficient to be able to spray it onto the steel plate, so the frequency and amplitude may be small and the distance 1 may be large.

The bath molten metal is continuously supplied from the melting tank to the molten metal storage container by adjusting the flow rate with a solenoid valve etc. to keep the liquid level constant. It is necessary to incorporate a heating element to keep the temperature of the molten metal constant during spraying.

The capacity of the molten metal storage container is desirably kept small to the extent that it does not cause any problems when controlling the amount of coating (C) from the viewpoint of suppressing the thermal effect on the ultrasonic transducer. It is sufficient that the area is 10x or less.

When a large amount of molten metal is deposited, such as when the coating thickness exceeds 100 μm, the influence of the size of the deposited particles on the uniformity of the coating becomes smaller, making it easier to achieve uniformity, so it is not always necessary to apply enough molten metal. It is not necessary to atomize the steel plate, and the molten metal may be applied to the steel plate by attaching a porous nozzle or the like to the spray hole and extruding and ejecting the molten metal by longitudinal vibration of an ultrasonic vibrator.

In this case, as a method to prevent clogging of the porous nozzle, a part of the ultrasonic transducer may be placed in contact with the porous nozzle, or
Alternatively, it is also effective to separately apply ultrasonic vibration to the porous nozzle.

Rather than simply having a smooth surface, the tip surface of the ultrasonic vibrator may be a concave surface or a rough surface with unevenness in order to hold the molten metal at the tip and efficiently spray or eject it forward. desirable.

After depositing the molten metal, the steel plate is rolled down by pressure rolls. There are two purposes for rolling down: one is to adjust the roughness of the coating surface, and the other is to improve coating adhesion.

If the rolling reduction is less than 0.5%, it is difficult to adjust the roughness of the coated surface and improve the coating adhesion, and if it exceeds 30%, the material becomes significantly hardened and the workability deteriorates. The temperature of the steel plate during rolling also affects the coating adhesion, and if the steel plate temperature is too low,
Since the effect of improving adhesion will be reduced, it is desirable that the reduction be carried out quickly so that the plated metal adheres.

The method of the present invention is not limited in any way to the positional relationship between the steel plate and the direction of spraying when molten metal is sprayed onto the steel plate. You can also spray it on.

(Example) In a 10% H, +90% N2 gas atmosphere,
A cold-rolled aluminum killed steel plate with a thickness of 0.30mm and a width of 200mm was rolled at 50m/! [After holding the steel plate at 640°C for 20 seconds while running at a threading speed of 11 nm, when the temperature of the steel plate during cooling was 400°C, the steel plate was heated to a molten state using an apparatus having the configuration shown in Fig. 1. Applying ultrasonic vibration to g,
The composition was applied from above (front side) and below (back side) of the steel plate.

As for the adhesion conditions, the melting temperature of M is 700°C. The slit width of the injection hole and the width of the tip of the ultrasonic vibrator are 4.2mm and 4.0mm, respectively, and the distance from the liquid level of the molten metal to the steel plate is The distance, that is, the injection distance is 10 mm above, 5 mm below, and 1 distance from the tip of the ultrasonic vibrator to the liquid surface.
For example, the longitudinal frequency of the ultrasonic transducer is 60 KHz.
, the amplitude was 45 μm.

Subsequently, when the temperature of the steel plate coated with M was 360° C., the steel plate was rolled with a pressure roll at a rolling reduction ratio of 1 inch.

After going through these steps, the final coating thickness of A2 is 4 on the front and back sides.
An M-coated steel plate having a thickness of 0 μm and a thickness of 0.34 mm was obtained.

This steel plate has a cup diameter of 65 mm and a drawing ratio (can height/can diameter) of 0.
．． 6. After drawing at 70℃, 98S RH, 3.
After aging for a week, the rate of occurrence of red rust (corrosion resistance) and peeling of the coating layer due to taping (plating adhesion) was determined in terms of area ratio.

For comparison, a plate with a thickness of 0.0 mm was prepared by cutting a plate using a known method.
In the case of a 34τ hot-dip aluminum-plated steel plate (plating thickness is 30 μm on one side), the area ratio of red rust occurrence is 40 cm and the area ratio of peeling off the coating is 30%, whereas the coated steel sheet prepared by the method of the present invention has no red rust occurrence and no peeling area ratio. No peeling of the coating was observed.

(Effects of the Invention) According to the method of the present invention, it is possible to easily manufacture aluminum-plated ultra-thin steel sheets, which were difficult to manufacture using conventional methods, as well as single-sided plated steel sheets, as well as high-tensile steel sheets with bake-hard properties. It also becomes possible to manufacture steel plates, etc.

In terms of quality, it is possible to prevent the development of an alloy layer that inhibits plating adhesion, so S
Addition of l becomes unnecessary, and a coated steel sheet with excellent corrosion resistance and adhesion can be obtained.

Also, in terms of equipment, it is different from conventional hot-dip plating, with a huge melting tank. It has various advantages, such as not requiring it and furthermore, it can be carried out in a small space on the cooling side of a continuous annealing line.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of the line configuration of the method of the present invention. 1... Steel plate 2... Atmosphere box 5
... Heating zone 4 ... Melting tank 5 ... Molten metal storage container 5a ... Spray hole 6 ... Molten plated metal 7 ... Ultrasonic vibrator 8 ... Pressure roll agent Patent attorney Tatsuo Chanoki Procedural Amendment (Voluntary) April 3, 1986

Claims (1)

[Claims] 1. A hot-dip plated metal storage container is placed in a non-oxidizing or reducing atmosphere and close to a traveling steel plate, and the hot-dip plated metal in the container is subjected to ultrasonic vibrations. A method of metal coating a steel plate, comprising spraying the hot-dip plated metal onto the surface of the steel plate to deposit the metal. 2. The method of metal coating a steel plate according to claim 1, wherein the temperature of the steel plate is in a temperature range of 150° C. or higher and lower than the melting point of the hot-dip plated metal. 3. The method of metal coating a steel plate according to claim 1, wherein the hot dip plated metal is aluminum.