JPS61243183A - Method and apparatus for chemical conversion treatment of metallic strip - Google Patents

Abstract

PURPOSE:To make possible the uniform formation of a specified quantity of chemical conversion film on the surface of a metallic strip by adjusting the controlling the depth at which the metallic strip is dipped into the chemical conversion treatment liquid in a dipping tank according to the increase or decrease in the passing speed of the metallic strip. CONSTITUTION:The method consists in passing continuously the metallic strip 10 via a deflector roll 12 and a dipping roll 13 into the chemical conversion treatment liquid in a dipping tank 11 and forming the chemical conversion film on the surface of the strip 10. The passing speed of the strip 10 in the above-mentioned method is detected by a speed detector 22 installed to the deflector roll 12 and an electric motor 20 is operated by a control device 21 according to the speed thereof to revolve a feed screw 17. A liquid level adjusting tank 14 is vertically moved by a nut 19 engaging with said feed screw by which the liquid level of the chemical conversion treatment liquid in the tank 11 connected with a flexible communicating pipe 15 is controlled. The reaction time for the chemical conversion treatment of the strip 10 is thereby maintained constant and the specified quantity of the uniform chemical conversion film is thus formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for chemical conversion treatment of metal strips such as thin steel sheets and plated steel sheets.

[Prior Art] Conventionally, as a continuous chemical conversion treatment method for metal strips such as thin steel sheets and plated steel sheets, the immersion method as shown in Fig. 2,
A single spray method as shown in FIG. 3 and a combination method of dipping and spraying as shown in FIG. 4 are used.

In FIGS. 2 to 4, 1 is a metal strip, 2 is an external tank, 3 is an immersion tank, 4 is a squeezing roll, 5 is a dam roll, and 6 is a spray nozzle. In this continuous chemical conversion treatment line, when the passing speed of the metal strip changes, the reaction time between the metal strip and the chemical conversion treatment solution in the chemical conversion treatment tank increases or decreases, and the amount of chemical conversion film formed on the surface of the metal strip changes. This not only affects the corrosion resistance and paint adhesion of the metal stop, but also changes the color tone of the metal stop, which impairs its commercial value.

Therefore, in the past, in order to be able to form a uniform and constant amount of chemical conversion film on the surface of the metal strip even when the threading speed of the metal strip changed, a method was used to respond to increases and decreases in the threading speed of the metal strip. Special Publication 59-5887, Japanese Patent Publication No. 5
As shown in 9-IE18878, (a) increasing or decreasing the number of dip tanks used in the immersion method; (b) increasing or decreasing the number of spray nozzles used in the spray method;
c) The concentration, components, temperature, etc. of the chemical conversion treatment solution are controlled.

[Problems to be Solved by the Invention] However, in the method (a) above, if an attempt is made to increase or decrease the number of immersion tanks used in response to a change in the threading speed of the metal strip, many immersion tanks will be used. is required, resulting in significantly higher equipment costs. Furthermore, if a smaller number of immersion tanks are used, it becomes difficult to keep up with the reaction time commensurate with changes in the strip passing speed, and the variation in the amount of chemical conversion coating increases, which adversely affects quality.

In addition, with method 1 (b), it is possible to follow changes in the threading speed of the metal strip by increasing or decreasing the number of sprays used, but equipment costs increase because many valve controls are required. Not only that, troubles such as nozzle clogging tend to occur, and a large amount of man-hours are required to inspect and replace the nozzles, reducing the productivity of the equipment.

In addition, method (e) above involves increasing and decreasing the concentration of the chemical conversion treatment liquid by replenishing and diluting the chemical conversion treatment liquid, which requires large-scale management and requires the necessary steps to homogenize the chemical conversion treatment liquid. Stirring takes time, and there is a delay in following changes in the threading speed. Similarly, the method using temperature adjustment also has a delay in follow-up.

The present invention always ensures a constant chemical conversion reaction time in response to changes in the threading speed of the metal strip, regardless of an increase or decrease in the number of immersion tanks used or the number of spray nozzles used.
The purpose is to make it possible to form a uniform and constant amount of chemical conversion film on the surface of a metal strip.

[Means for Solving the Problems] The first aspect of the present invention is to provide a metal strip in which a metal strip is continuously passed through a chemical conversion treatment solution in a dipping tank to form a chemical conversion film on the surface of the metal strip. In the chemical conversion treatment method, the immersion depth of the metal strip in the chemical conversion treatment solution in the immersion tank is controlled to increase or decrease in accordance with the increase or decrease in the passing speed of the metal strip. In a metal strip chemical conversion treatment apparatus in which a metal strip is continuously passed through a chemical conversion treatment liquid in a dipping tank to form a chemical conversion film on the surface of the metal strip, a liquid level adjustment tank communicating with the dipping tank is used. and a drive device that allows the liquid level adjustment tank to be moved to any position in the vertical direction.The drive device is operated according to the increase or decrease in the passing speed of the metal strip, and the set position of the liquid level adjustment tank is adjusted to prevent immersion. The immersion depth of the metal strip in the chemical conversion treatment liquid in the tank is controlled to increase or decrease.

[Function] According to the metal strip chemical conversion treatment method and apparatus according to the present invention, the immersion depth of the metal strip is increased or decreased in response to an increase or decrease in the passing speed of the metal strip. It is possible to continuously increase and decrease the contact length and keep the reaction time between the metal strip and the chemical conversion treatment liquid constant. This makes it possible to produce a uniform and constant amount of stable chemical conversion film on the surface of the metal strip.

[Example] FIG. 1 is a schematic diagram showing an example of the present invention. In FIG. 1, 10 is a metal strip, 11 is a vertical dipping tank, 12 is a deflector roll, and 13 is a dipping roll. The metal strip 10 is continuously passed through a chemical conversion treatment liquid in an immersion tank 11 so that a chemical conversion film can be formed on its surface.

14 is a liquid level adjustment tank. The liquid level adjustment tank 14 is
It is connected to the bottom of the immersion tank 11 via a flexible communication pipe 15, and is supported by a guide rod 16 so as to be movable in the vertical direction.

17 is a feed screw. The feed screw 17 is rotatably supported by the support portion 18 at both ends thereof, and is screwed into a stop 19 integrated with the liquid level adjustment tank 14, and serves as a drive device in the present invention. By driving the electric motor 20, forward rotation and reverse rotation are possible.

That is, the electric motor 20 makes it possible to move the liquid level adjustment tank 14 to any position in the vertical direction. At this time, the liquid level in the immersion tank 11 moves up and down following the change in the liquid level in the liquid level adjustment tank 14, and is set to the same level as the new liquid level in the liquid level adjustment tank 14.

21 is a control device, and 22 is a speed detector. The speed detector 22 is capable of detecting the threading speed of the metal strip IO via the rotation speed of the deflector roll 12.

Reference numeral 23 denotes an ultrasonic detector or the like for detecting the liquid level in the immersion tank 11, and the detection result can be transmitted to the control device 21. When the passing speed of the metal strip 10 detected by the speed detector 22 increases or decreases, the control device 21 rotates the electric motor 20 in the forward or reverse direction, and adjusts the set position of the liquid level adjustment tank 14 to adjust the immersion tank l.
Adjust the liquid level in the immersion tank l, thereby adjusting the liquid level in the immersion tank l
It is possible to increase or decrease the immersion depth of the metal strip 10 in the chemical conversion treatment liquid in the liquid.

Therefore, when the threading speed of the metal strip 10 is maximum, the contact length of the metal strip 10 with the chemical conversion treatment liquid is maximized in order to keep the reaction time between the metal strip 10 and the chemical conversion treatment liquid constant. Therefore, the control device 21 sets the liquid level adjustment tank 14 to the maximum height position. At this time, the liquid level in the immersion tank 11 is set to the same maximum height level as the liquid level in the liquid level adjustment tank 14, as shown by A in FIG.

On the other hand, when the passing speed of the metal strip 10 is the minimum, the contact length of the metal strip 10 with the chemical conversion treatment liquid is minimized in order to keep the reaction time between the metal strip 10 and the chemical conversion treatment liquid constant. In order to achieve this, the control device 21 sets the liquid level adjustment tank 14 to the minimum height position. At this time, the liquid level in the immersion tank 11 is set to the same minimum height level as the liquid level in the liquid level adjustment tank 14, as shown by B in FIG.

That is, when the threading speed of the metal strip IO increases or decreases between the maximum and minimum values, the control device 21 adjusts the liquid level in the immersion tank 11 to an appropriate level between the maximum height level A and the minimum height level B. Switch to level and set metal strip 10
By increasing or decreasing the immersion depth of the metal strip 10, the contact length of the metal strip 10 with the chemical conversion treatment liquid can be continuously increased or decreased, and the reaction time between the metal strip 10 and the chemical conversion treatment liquid can be kept constant. This allows the metal strip lO
It is now possible to generate a uniform and constant amount of stable chemical conversion film on the surface of the metal strip, preventing unevenness in color tone, corrosion resistance, paint adhesion, etc. within the same metal strip coil, and obtaining high quality products. becomes possible.

Note that 24 is a replenishment tank for chemical conversion treatment liquid.

That is, as the chemical conversion treatment on the metal strip IO progresses, and as the chemical conversion treatment solution in the immersion tank 11 decreases or its composition changes, the chemical conversion treatment solution in the supply tank 24 is transferred to the immersion tank 11 by the operation of the liquid feed pump 25. Replenishment is possible.

In addition, in carrying out the present invention, a plurality of immersion devices are provided that can increase or decrease the immersion depth of the metal strip as described above depending on the speed range of the metal strip and the type of chemical conversion treatment solution, and these are arranged in series. It is also possible to use a multi-tank type.

Also, depending on the speed range of the metal strip and the type of chemical conversion treatment liquid, other chemical conversion treatment tanks such as a one-way spray treatment tank may be used before or after the immersion device that can increase or decrease the immersion depth of the metal strip as described above. It may also be added.

[Effects of the Invention] As described above, according to the metal strip chemical conversion treatment method and apparatus according to the present invention, the threading speed of the metal strip can be increased or decreased without changing the number of dipping tanks used or the number of spray nozzles used. It becomes possible to always ensure a constant chemical conversion treatment reaction time against changes, and to form a uniform and constant amount of chemical conversion coating on the surface of the metal strip.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, FIG. 2 is a schematic diagram showing a conventional example, and FIG. 3 is a schematic diagram showing another conventional example.
FIG. 4 is a schematic diagram showing another conventional example. lO...Metal strip, 11...Immersion tank, 1
4...Liquid level adjustment tank, 17...Feed screw, 19.
... Nut, 20... Electric motor, 21... Control device,
22...Speed detector. Agent Patent Attorney Osamu Shiokawa 2 Figure 3 Figure 4

Claims (2)

[Claims] (1) In a metal strip chemical conversion treatment method in which a metal strip is continuously passed through a chemical conversion treatment solution in an immersion tank to form a chemical conversion film on the surface of the metal strip, an increase or decrease in the passing speed of the metal strip. 1. A method for chemical conversion treatment of a metal strip, characterized in that the depth of immersion of the metal strip in a chemical conversion treatment solution in an immersion tank is increased or decreased according to the method. (2) In a metal strip chemical conversion treatment device in which a metal strip is continuously passed through a chemical conversion treatment liquid in a dipping tank and a chemical conversion film is formed on the surface of the metal strip, liquid level adjustment that communicates with the dipping tank The tank and the drive device that can move the liquid level adjustment tank to any position in the vertical direction, and the drive device is operated according to increases and decreases in the passing speed of the metal strip, and the set position of the liquid level adjustment tank is adjusted. A metal strip chemical conversion treatment apparatus characterized in that the immersion depth of the metal strip in a chemical conversion treatment liquid in an immersion tank is controlled to increase or decrease.