JPH04200903A - Hot rolling method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a hot rolling method for hot rolling a hot rolled material while suppressing roughness of the work roll by cooling the material.

[Prior Art and Problems to be Solved by the Invention] In hot rolling, a hot-rolled material (strip) at a high temperature is rolled under a high load by a work roll, so that the surface of the work roll is likely to become rough. This tendency is particularly noticeable in the first stage of finish rolling.

If the surface of the work roll becomes rough as described above, the quality of the strip deteriorates and is lost, so it is important to suppress the rough surface of the work roll.

In order to suppress such rough skin, conventional methods include supplying oil to the backup roll to lubricate it and reduce the pressure exerted on the work roll, and methods to make the reduction blade of the work roll smaller to achieve a lighter reduction. etc. are being attempted.

However, the former method is insufficiently effective, and the latter method involves process difficulties. Therefore, there is a need for an effective method for suppressing work roll surface roughness in place of these methods.

This invention was made in view of such circumstances, and
It is an object of the present invention to provide a hot rolling method that can effectively suppress surface roughening of work rolls without causing any difficulties in the process.

[Means and effects for solving the problem] The hot rolling method according to the present invention involves bringing a cooling medium into contact with the hot rolled material immediately before the hot rolled material is bitten by the work rolls, thereby reducing the temperature of the hot rolled material. It is characterized by hot rolling with the surface cooled.

Conventionally, cooling water has been injected onto the strip surface during hot rolling. However, since the conventional cooling water injection to the strip was aimed at preventing the formation of high-temperature scale, the strip was cooled immediately after exiting the rolling mill. However, there is a long way to go before it gets caught in the work roll of the next rolling mill, so -
Once the surface temperature of the strip has decreased, the temperature will rise again due to internal recuperation, and then the strip will be bitten into the work roll. Therefore, it was not possible to alleviate the thermal shock imparted to the work roll, and there was no effect in suppressing rough skin. In contrast, in the present invention, the strip surface is cooled immediately before the strip is bitten by the work rolls, so the strip can be rolled before the surface temperature rises due to internal recuperation. That is, since the strip surface is hot-rolled by the work roll in a cooled state, roughening of the surface of the work roll can be effectively suppressed.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a side view showing a rolling mill for carrying out the hot rolling method according to the present invention. The strip 1 is guided by a Zide guide 4 and rolled onto the rolling stand 1 along the rolling direction A.
0. In the rolling stand 10, the strip 1 is rolled at an appropriate rolling reduction ratio by a pair of work rolls 2 pulled up by a backup roll 3.

In addition, adjacent cooling water headers 5 are provided above and below near the rolling direction A'' of the work roll 2, and the strip 1 immediately before being bitten by the work roll 2 is cooled from the spout of the cooling water header 5. Water is sprayed.

As shown in FIG. 2, this cooling water header 5 is connected to a cooling water pipe 6, and this pipe 6 is supported by a support member (not shown). Note that the number of cooling water headers 5 may be one of the upper and lower ones.

In this way, the surface of the strip 1 is cooled by the cooling water spouted from the header 5, but since that position is just before it is bitten by the work roll 2, the surface temperature of the strip increases due to recuperation from the inside. The previous strip 1 with a sufficiently cooled surface is transferred to the work roll 2.
It will be caught in. Therefore, thermal shock to the work roll 2 is alleviated, and roughening of the surface of the work roll 2 is effectively suppressed. In addition, since the cooling water in this case is for cooling only the strip surface, the cooling water header 5
From IIl! For example, the flow rate of cooling water is 20Ω/
A flow rate of approximately 1/10 to 1/100 of the cooling water flow rate in conventional roll cooling is sufficient.

Next, the results of actual hot rolling using such a method will be explained in comparison with those obtained using a conventional method.

Here, a proximal cooling water header was installed on the lower surface of Fl (first stand) of the finishing rolling mill, and cooling water was injected onto the strip. After rolling the thin material cycle (approximately 1200"), the work roll was pulled out and its surface properties were evaluated using the skin points. Here, the skin points were taken from the roll skin immediately after grinding, and the roll skin taken out after the rolling was finished. The skin was evaluated on a four-point scale of 8.6 and 4.2 points (the higher the number, the better the skin).The results are shown in Table 1.

Table 1 As is clear from Table 1, in the case of the example employing the method of the present invention, the skin score was the highest at 8 points in all cycles, whereas in the case of the conventional example in which no cooling water was used. The average is 6.
4, which was lower than that of the example. That is, the effect of suppressing rough skin of the work roll of the present invention was confirmed.

In addition, by adopting the present invention, thin plates (1, 2 to 3
The number of times of continuous rolling (mm thickness) increases.

In other words, since the pressure during rolling of thin plates is usually high, a thick plate is rolled after several coils of thin plates are rolled, but by adopting the present invention, roughening of the work roll surface is suppressed, so continuous rolling of thin coils is possible. The number can be increased. Incidentally, for a thin plate with a thickness of 1.6 mm, conventionally a thick plate was rolled after 8 continuous coils were rolled, but by adopting the present invention, continuous rolling of 30 coils became possible. Therefore, it is possible to reduce yield loss and increase production efficiency by 1.

Furthermore, as a result of suppressing rough skin, the ratio of hot flakes in the rolling mill increases.

[Effects of the Invention] According to the present invention, since the hot rolled material whose surface has been cooled is bitten by the work roll, roughening of the surface of the work roll can be effectively suppressed without causing any difficulty in the process. can. Accordingly, the quality of the product after rolling can be improved.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a rolling mill for carrying out the hot rolling method according to the present invention, and FIG. 2 is a plan view showing the main parts thereof. 1; Strip (pressure 0.2; Work roll; 3; Backup roll; 4; Side guide; 5; Cooling water header applicant patent attorney Takehiko Suzue

Claims (1)

[Claims] A hot rolling method characterized by bringing a coolant into contact with a hot rolled material immediately before the hot rolled material is bitten by a work roll, and hot rolling the hot rolled material in a state where the surface of the hot rolled material is cooled.