JPH02274302A - Method for preventing generation of oil pattern at cold rolling of stainless steel strip - Google Patents

Abstract

PURPOSE:To prevent the generation of oil patterns on the surfaces of a stainless steel strip by spraying a cooling medium to the stainless steel strip right after the strip is cold rolled to forcibly cool the stainless steel strip down to a specific temp. or below. CONSTITUTION:A rolling mill lubricant of an oil-in-water type emulsion is sprayed from rolling mill lubricant nozzles 3 toward rolling rolls 2 in order to improve the cooling and rolling characteristics of the rolling roll 2 and stainless steel strip 1 and to remove the worn powder to be generated at the time of the cold rolling of the stainless steel strip 1. The cooling medium is sprayed from cooling medium injecting nozzles 4 in order to forcibly cool the stainless steel strip right after the cold rolling by cold rolling mills down to the temp. below 100 deg.C. A high cooling effect and a good result are obtd. if the cooling medium is sprayed from the nozzles 4 in the form of the mists formed of the rolling mill lubricant of the oil-in-water type emulsion and air.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for cold rolling a stainless steel strip using an oil-in-water emulsion rolling oil consisting of rolled crude oil and water, even during high-speed rolling. The present invention relates to a method for preventing the occurrence of uneven gloss patterns (hereinafter referred to as wave patterns) caused by rolling oil on the surface of a stainless steel strip.

[Conventional technology]

Conventionally, in the cold rolling process of metal strips, the rolling rolls and metal strips are cooled, and the rollability of the metal strips is improved.

Rolling oil is used for purposes such as removing wear particles generated from metal bands and the like. In recent years, oil-in-water emulsion rolling oil consisting of rolled crude oil and water has been used as this rolling oil.
Low viscosity mineral oil 80-90%2, consisting of 7-9% rolled crude oil, 5-10% synthetic oil, 5-10% emulsifier, and other small amounts of rust preventives and antifoaming agents, and 93-91% water. is used.

However, when stainless steel strip is cold-rolled, especially at high speed, using such oil-in-water emulsion rolling oil, the surface of the cold-rolled stainless steel strip has a good gloss, but it is coated with oil from the early stage of cold rolling. There was a problem in that an oil film-like pattern in which the flow remained in the form of streaks was generated.

[Problem to be solved by the invention]

To prevent this kind of oil film from occurring.

It is desirable to develop a rolling oil with a composition that does not produce an oil film, but cold rolling of stainless steel strips depends on the cold rolling rate, threading speed, steel type 2 surface properties of the stainless steel strip, and degree of work hardening. Currently, it is impossible to create a composition of rolling oil used under various conditions such as such that oil film-like formations do not always occur, as it has not yet been determined what factors in the rolling oil are responsible for the formation of oil film-like formations. It is no exaggeration to say that.

Therefore, the present invention is directed to cold rolling, particularly high speed rolling, of stainless steel strips using oil-in-water emulsion rolling oil that has come into use in recent years.

An object of the present invention is to provide a method for effectively preventing the occurrence of an oil film-like appearance caused by rolling oil on the surface of a stainless steel strip.

[Means to solve the problem]

The present inventors conducted various experiments to solve the above problems,
In particular, cold rolling of stainless steel strips using oil-in-water emulsion rolling oil is carried out immediately after the rolling exit by varying the rolling speed, rolling ratio, steel type and thickness of the stainless steel strip, and rolling oil temperature. The number of threaded coils at each temperature is 10 so that the temperature of the stainless steel strip becomes various.
As a result of testing the coil, the results shown in Table 1 were obtained.

The results in Table 1 below show that when the temperature of the stainless steel strip on the rolling exit side rises above 100°C, the incidence of oil film-like formation increases dramatically, and this is due to This is thought to be because as the temperature of the stainless steel strip increases, the viscosity of the rolling oil adhering to the surface of the stainless steel strip decreases, causing the rolling oil to be distributed unevenly.

The present invention was made based on this knowledge, and it is possible to prevent the formation of an oil film on the surface of the rolled stainless steel strip by forcibly cooling the stainless steel strip immediately after cold rolling to a temperature of 100°C or less. In particular, if this forced cooling is carried out by spraying oil-in-water emulsion rolling oil, which is the same as the rolling oil used during cold rolling of stainless steel strips, subsequent treatment of the stainless steel strips can be done in the same manner as before, and the cooling process can be completed. The oil-in-water emulsion rolling oil used during rolling and forced cooling can be recovered and used again.

When oil-in-water emulsion rolling oil is used for forced cooling, mixing the oil-in-water emulsion rolling oil with cooling air and spraying it in the form of a mist is more efficient and improves cold rolling of stainless steel strips. The present invention was completed by discovering that when cold rolling mills are installed in tandem, it is only necessary to forcefully cool the stainless steel strip on the outlet side of the final cold rolling mill.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for preventing oil film formation during cold rolling of stainless steel according to the present invention will be explained in detail with reference to the drawings.

FIG. 1 is an explanatory diagram showing a state in which the method of the present invention is implemented;
The second @ is an explanatory diagram showing a state in which the method of the present invention is implemented in cold rolling mills installed in tandem.

In the drawing, 1 is a stainless steel strip to be cold rolled, 2 is a rolling roll of a cold rolling mill, 3 is a rolling oil injection nozzle that sprays oil-in-water emulsion rolling oil toward the rolling roll 2 of the cold rolling mill. 4 is a cooling medium injection nozzle that sprays a cooling medium to forcefully cool the temperature of the stainless steel strip 1 immediately after cold rolling in a cold rolling mill to a temperature of 100° C. or less; 5 is the stainless steel to be cold rolled; a payoff reel that unwinds the strip 1; 6 a deflector roll that changes the traveling direction of the stainless steel strip 1 supplied from the payoff reel 5;
7 is a tension reel for winding the cold-rolled stainless steel strip 1, and 8 is a cold rolling mill for cold-rolling the stainless steel strip 1 when the cold rolling mills are installed in tandem. Input pinch rolls 9 supply the stainless steel strip 1 to be rolled, input pinch rolls 8 and outlet pinch rolls 9 send out the cold-rolled stainless steel strip 1 after passing through a cold rolling mill.

[For production]

A stainless steel strip 1 to be cold rolled is unwound from a payoff reel 5, its traveling direction is changed by a deflector roll 6, and if necessary, the stainless steel strip 1 is passed through an input pinch roll 8 and transferred to a rolling roll 2 of a cold rolling mill. The sheet is passed through a plate and cold-rolled, and then, if necessary, passes through an outlet pinch roll 9, has its traveling direction changed by a deflector roll 6, and is wound onto a tension reel 9. When cold rolling the stainless steel strip 1 in this way, the rolling rolls 2 of the cold rolling mill and the stainless steel strip 1 are cooled, the rollability of the stainless steel strip 1 is improved, and the wear that occurs from the stainless steel strip 1, etc. Oil-in-water emulsion rolling oil is sprayed from a rolling oil injection nozzle 3 toward the rolling rolls 2 of the cold rolling mill for purposes such as removing powder. Conventionally, an uneven luster pattern, that is, an oil film appearance, has occurred on the surface of the stainless steel strip 1 that has been cold rolled in this manner.

Therefore, in the present invention, in order to prevent the occurrence of such an oil film-like appearance on the surface of the stainless steel strip 1, the temperature of the stainless steel strip 1 immediately after being cold rolled in a cold rolling mill is set to 1.
The cooling medium is sprayed from the cooling medium injection nozzle 4 in order to forcefully cool the temperature to below 00°C, and as the cooling medium sprayed from the cooling medium injection nozzle 4, it is impossible to reuse expensive oil-in-water emulsion rolling oil. However, it is not preferable to use cooling air, the same oil-in-water emulsion rolling oil as the oil-in-water emulsion rolling oil sprayed from the rolling oil injection nozzle 3, or the oil-in-water emulsion rolling oil sprayed from the rolling oil injection nozzle 3. A mist-like material composed of an oil-in-water emulsion rolling oil, which is the same as oil, and cooling air is preferably used. In particular, it is preferable to spray a mist composed of an oil-in-water emulsion rolling oil and air because it has a high cooling effect.

As described above, in the method of the present invention, by spraying a cooling medium from the cooling medium injection nozzle 4 to forcefully cool the temperature of the stainless steel IF1 immediately after cold rolling to a temperature of 100°C or less, stainless steel strip 1
It is possible to prevent an oil film from forming on the surface.

〔Example〕

As shown in Figure 2, when cold rolling a stainless steel strip using an oil-in-water emulsion rolling oil consisting of rolled crude oil and water using a tandem cold rolling mill equipped with four Sensimir mills, the final stand A cooling medium injection nozzle is installed immediately after the exit of the stainless steel strip from Senshimia Mill to spray an oil-in-water emulsion rolling oil, which is the same as the rolling oil used during cold rolling, onto the stainless steel strip. Cold rolling was carried out with and without injection of emulsion rolling oil.

Table 2 shows the main specifications of this tandem cold rolling mill.

Table 2 Table 3 shows the results of cold rolling various stainless steel strips using this tandem cold rolling mill.

Margin below As is clear from the results in Table 3, oil-in-water emulsion rolling oil, which is the same as the rolling oil used during cold rolling, was used as a cooling medium on the rolling exit side of stainless steel strips rolled under various conditions. When high-speed rolling was performed without spraying, wave patterns were observed, but when oil-in-water emulsion rolling oil, which is the same as the rolling oil used during cold rolling, was sprayed as a cooling medium, the wave pattern appeared immediately after the rolling exit side. Since the temperature rise of the rolled stainless steel strip can be suppressed in this process, the occurrence of wavy patterns can be prevented. That is, the effect of preventing oil pattern generation by spraying the cooling medium was sufficiently confirmed.

In addition, if the cooling medium is not sprayed, the rolling speed must be regulated due to the generation of an oil film, but by spraying the cooling medium, the temperature rise of the rolled stainless steel strip can be reduced by 100%.
It was also confirmed that there is no need to regulate the rolling speed if it can be kept below ℃.

〔Effect of the invention〕

As described in detail above, the method for preventing oil pattern generation during cold rolling of stainless steel strip according to the present invention has the following effects.

(1) Before implementing the method of the present invention, the oil pattern occurrence rate was 2.7% on average, but after implementation, the occurrence of wavy patterns can be completely prevented.

(2) Equipment costs are extremely low because it is sufficient to newly install a simple coolant injection nozzle for forced cooling of the stainless steel strip on the rolling exit side.

(3) Implementation of the method of the present invention does not require any special labor, and does not impede workability or production efficiency.

(4) In order to prevent the occurrence of wave patterns on the surface of the stainless steel strip on the exit side of rolling, it has been necessary to restrict the rolling speed, but by implementing the method of the present invention, the rolling speed can be increased. This makes it possible to improve production efficiency.

(5) The cooling medium injected from the cooling medium injection nozzle is oil-in-water emulsion rolling oil that is the same as the rolling oil used during cold rolling of stainless steel strips, or a mist made of a mixture of this oil-in-water emulsion rolling oil and cooling air. It is very economical to use the rolling oil used during cold rolling and forced cooling because it can be simply cleaned and reused as is. It can also be used as a pump that pumps rolling oil to the injection nozzle.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a state in which the method of the present invention is implemented;
FIG. 2 is an explanatory diagram showing a state in which the method of the present invention is implemented in cold rolling mills installed in tandem. In the drawings 1...Stainless steel strip 2...Rolling roll 3 of a cold rolling mill...Rolling oil injection nozzle 4...Cooling medium injection nozzle 5...Payoff reel 6... ... Deflector roll 7 ... Tension reel 8 ... Entry side pinch roll 9 ... Output side pinch roll 21 Fig. 12 ! l!

Claims (1)

[Claims] 1. When cold rolling a stainless steel strip using an oil-in-water emulsion rolling oil consisting of rolled crude oil and water, a cooling medium is sprayed onto the stainless steel strip immediately after cold rolling. A method for preventing oil pattern formation during cold rolling of stainless steel, characterized in that oil pattern formation on the surface of a stainless steel strip is prevented by forcibly cooling the stainless steel strip to a temperature of 100° C. or lower. 2. The method for preventing oil pattern generation during cold rolling of stainless steel according to claim 1, wherein oil-in-water emulsion rolling oil, which is the same as the rolling oil used during cold rolling of stainless steel strips, is used as the cooling medium. 3. The stainless steel according to claim 1, wherein an oil-in-water emulsion rolling oil, which is the same as the rolling oil used during cold rolling of the stainless steel strip, is mixed with cooling air as a cooling medium, and the mixture is sprayed in the form of a mist to forcibly cool the stainless steel. Method for preventing oil pattern formation during cold rolling. 4. Any one of claims 1 to 3, wherein the cold rolling mills for cold rolling the stainless steel strip are installed in tandem, and the stainless steel strip is forcibly cooled immediately after exiting the final cold rolling mill. A method for preventing oil pattern formation during cold rolling of stainless steel as described in .