JP2000064071A - Metal strip cleaning method after cold rolling - Google Patents

Abstract

(57) [Problem] To provide a method for cleaning a metal strip after cold rolling, which can improve the cleanliness by cleaning the metal strip. SOLUTION: A cleaning gas mixture is introduced into a tank,
This is a metal strip cleaning method after cold rolling, in which a gas-dissolved cleaning liquid is generated while maintaining the temperature at 30 to 60 ° C., and the gas-dissolved cleaning liquid is sprayed onto the metal strip for cleaning.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for cleaning a metal strip after cold rolling.

[0002]

2. Description of the Related Art In cold rolling of a metal strip, rolling oil is generally used, and therefore rolling oil adheres to the metal strip after rolling. The metal strip after such cold rolling is subsequently subjected to heat treatment in order to improve workability,
During this heat treatment, stains are generated by the attached rolling oil. Therefore, the metal strip after cold rolling is cleaned and degreased, and then the heat treatment as described above is performed. Then, as a method of cleaning the metal strip, a cleaning liquid is introduced into the tank, gas is pressed into the surface of the cleaning liquid in the tank to maintain a high pressure state, and the gas is mixed into the cleaning liquid from the surface of the cleaning liquid and the gas is removed. It is disclosed in JP-A-6-71233 and JP-A-8-253883 that the gas-dissolved cleaning liquid is dissolved in the cleaning liquid and is sprayed onto the metal strip for cleaning.

[0003]

In the above-described metal strip cleaning method after cold rolling, it is difficult to increase the contact area between the cleaning liquid and the gas, and it is possible to efficiently mix the gas into the cleaning liquid. In addition, the amount of dissolved gas in the cleaning liquid may be insufficient due to gas mixing from the surface of the cleaning liquid. Therefore, the generation of fine bubbles in the cleaning liquid due to the metal band injection of the gas-dissolved cleaning liquid is reduced, and it is difficult to obtain a satisfactory cleaning effect. Further, since the upper space of the cleaning liquid in the tank is maintained at a high pressure, it is necessary to make the tank rigid, and an air supply system such as a compressor is additionally provided, which increases the equipment cost. Moreover, there is a problem that the running cost due to the operation of the compressor and the like increases. The method of the present invention has been made to advantageously solve such a problem, and highly efficiently mixes a gas into the cleaning liquid, and yet the gas is reliably contained in the cleaning liquid, and the sufficiently dissolved cleaning liquid to the metal strip. An object of the present invention is to provide a method for cleaning a metal strip after cold rolling which can be sprayed and reliably cleaned.

[0004]

The method of the present invention is characterized in that a gas-mixed cleaning liquid is introduced into a tank to
A method for cleaning a metal strip after cold rolling, characterized in that a gas-dissolved cleaning liquid is generated while being maintained at -60 ° C, and the gas-dissolved cleaning liquid is sprayed onto a metal band for cleaning.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The gas-mixed cleaning liquid introduced into the tank as described above is provided, for example, with an ejector or the like as a gas-liquid mixer in the cleaning liquid supply pipe on the tank entrance side, and at the same time as supplying the cleaning liquid, air or the like is supplied as gas. By,
The contact area between the gas and the cleaning liquid can be significantly increased, and a large amount of gas is mixed into the cleaning liquid in a short time to generate a gas-mixed cleaning liquid and introduce it into the tank. By thus introducing the gas-mixed cleaning liquid into the tank, a stirring action occurs in the tank, and the gas mixture of the gas-mixed cleaning liquid can be sufficiently and surely dissolved in the cleaning liquid.

In this way, the gas is dissolved in the cleaning liquid in the tank, but the surplus gas that is not dissolved becomes bubbles and floats in the cleaning liquid and moves to the space above the surface of the cleaning liquid. Although it may be diffused outside the tank, this excess gas is recovered and supplied to the gas-liquid mixer as described above,
The shortage is advantageous because the gas pressure in the equipment system can be stably maintained by supplying (supplementing) new gas to supply the required amount.

As described above, when the gas-dissolved cleaning liquid is generated, the temperature of the gas-mixed cleaning liquid in the tank is set to 30-6.
By maintaining it at 0 ° C as a gas-dissolved cleaning solution,
The gas solubility in the gas-mixed cleaning liquid can be improved. Therefore, when the gas-dissolved cleaning liquid is sprayed on the surface of the metal strip, it becomes a fine cleaning liquid containing gas and liquid, and a strong impact force is generated by the collision with the metal strip, further enhancing the action of removing foreign matter such as adhered rolling oil. be able to. However, if the temperature of the gas-mixed cleaning liquid is lower than 30 ° C., the fluidity of the rolling oil is lowered, which is not preferable for removing the foreign matter from the steel sheet. Further, if it exceeds 60 ° C., the gas solubility is similarly lowered, which is not preferable. A more suitable temperature for improving the gas solubility and obtaining a high cleaning effect is 40 to 50 ° C.

After forming the gas-dissolved cleaning liquid in the tank in this way, for example, the high-pressure gas-dissolved cleaning liquid is supplied to the nozzle from the gas-dissolved cleaning liquid supply pipe on the outlet side of the tank via the pump to cool the metal strip after cold rolling. By injecting into, the jetted gas-dissolved cleaning liquid is rapidly depressurized at the same time as being jetted from the nozzle, and the dissolved gas in the gas-dissolved cleaning liquid is vaporized to generate many fine bubbles. In this way, the gas-dissolved cleaning liquid becomes a cleaning liquid containing fine bubbles, and when it impinges on the metal band, it collides with the impact force at the time of collision, and the impact force at which many fine bubbles burst due to the collision causes the rolling oil to adhere to the metal band. It is possible to reliably remove foreign matter such as.

In this manner, as the cold-rolled metal strip that can be washed, for example, a metal strip such as a steel strip, an aluminum strip, or a copper strip can be advantageously washed.

Next, an example of the method of the present invention will be described with reference to the drawings. In FIG. 1, a cleaning liquid supply pipe 2 below the tank 1
The gas-liquid mixer 3 and the pump 4a are provided in the above, and the excess gas recovery pipe 5 is connected to the gas-liquid mixer 3 from the upper part of the tank 1.
A gas supply pipe 6 is provided in the surplus gas recovery pipe 5. on the other hand,
As shown in the figure, in the tank 1, a gas-dissolved cleaning liquid supply pipe 7 is provided with a pump 4b and a water vapor supply pipe 9. Thus, the cleaning liquid is supplied to the gas-liquid mixer 3 via the pump 4a, and the gas is supplied from the gas supply pipe 6 to the gas-liquid mixer 3 to mix the gas with the cleaning liquid to generate the gas-mixed cleaning liquid, which is stored in the tank. Introduce into 1. Tank 1 like this
Steam is supplied from the steam supply pipe 9 to the gas-mixed cleaning liquid 8 introduced thereinto, while maintaining the liquid temperature at 30 to 60 ° C., while the stirring action occurs in the tank 1, the gas-mixed cleaning liquid 8 is generated.
The gas therein is dissolved in the cleaning liquid 8 to form a gas-dissolved cleaning liquid. Thus, the surplus gas in the gas-dissolved cleaning liquid floats upward and is supplied to the gas-liquid mixer 3 from the surplus gas recovery pipe 5, and the shortage is supplied to the gas-liquid mixer 3 from the gas supply pipe 6. The gas-dissolved cleaning liquid thus generated in the tank 1 is supplied from the gas-dissolved cleaning liquid supply pipe 7 to the nozzle (not shown) via the pump 4b, and is sprayed to the metal band (not shown) for cleaning. Is.

[0011]

EXAMPLES Next, examples of the method of the present invention will be given together with comparative examples.

[Table 1]

Note 1: The cleaning liquid is water and the gas is air. Note 2: Ejector is used as the gas mixer. Note 3: The supply amount and supply pressure of the cleaning liquid in Comparative Examples 1 to 3 are the supply amount and supply pressure to the tank (no gas mixed cleaning liquid is used). Note 4: The atmospheric pressure above the tank is the atmospheric pressure between the liquid surface inside the tank and the tank ceiling (lid). In Comparative Examples 1 to 3, gas was pressed into the upper space in the tank by a compressor, and the gas was mixed into the liquid from the surface of the cleaning liquid in the tank and dissolved. Note 5: As described above, the gas was continuously supplied into the tank, and the gas-dissolved cleaning liquid was supplied from the tank to the nozzle to spray-clean the metal strip (passing speed: 750 mpm). Note 6: Metal strips are Fe: steel strip, Al: aluminum strip,
Cu: Copper strips after cold rolling, respectively (width: 800
mm, plate thickness: 0.2 mm). Note 7: Cold rolling oil is steel strip: cationic rolling oil, oil / water emulsion type rolling oil (generally used),
Aluminum and copper strips use nonionic rolling oil of oil / water emulsion type. Note 8: As for the cleaning result, a white paper was brought into contact with the metal strip after cleaning for 5 seconds to visually judge the degree of contamination. ◎: No stain,
◯: Slight stains occurred, Δ: Light black stains occurred (no practical problem), ×: Black stains occurred.

[0013]

According to the method of the present invention, the cleanliness of the metal strip can be improved by cleaning, and the quality and yield of the metal strip can be improved. Further, it is possible to obtain an excellent effect that a gas-dissolved cleaning liquid in which gas is sufficiently and surely dissolved can be produced at low cost.

[Brief description of drawings]

FIG. 1 is a side view showing an example of the method of the present invention.

[Explanation of symbols]

1 tank 2 Cleaning liquid supply pipe 3 gas-liquid mixer 4a pump 4b pump 5 Surplus gas recovery pipe 6 gas supply pipe 7 Gas-dissolved cleaning liquid supply pipe 8 Gas mixture cleaning liquid 9 Water vapor supply pipe

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hisashi Kikukawa             5-3 Tokai-cho, Tokai-shi, Aichi Nippon Steel Corporation             Ceremony Company Nagoya Steel Works F term (reference) 3B116 AA08 AB13 BB21 BB81 BB82                       BB90                 3B201 AA08 AB13 BB21 BB81 BB82                       BB90 BB92 BB98                 4K053 PA02 PA06 PA10 PA12 QA05                       SA05 SA19 TA03 XA11 XA22

Claims (3)

[Claims] 1. A gas mixture cleaning solution is introduced into a tank,
A method for cleaning a metal strip after cold rolling, which comprises producing a gas-dissolved cleaning solution while maintaining the temperature at 30 to 60 ° C., and spraying the gas-dissolved cleaning solution onto a metal strip for cleaning. 2. The method for cleaning a metal strip after cold rolling according to claim 1, wherein a gas-mixed cleaning liquid in which a gas is mixed with the cleaning liquid is introduced into the tank by an ejector at the tank entrance side. 3. An excess gas in the gas-dissolved cleaning liquid generated in the tank is recovered and mixed with the cleaning liquid introduced into the tank to form a gas mixed cleaning liquid, and the gas mixed cleaning liquid is introduced into the tank. Claim 1 or Claim 2
The method for cleaning a metal strip after cold rolling according to 1.