JPS5910403A - Cold tandem rolling device - Google Patents

Abstract

PURPOSE:To enable the increase in rolling speed without decreasing the quality of the surface characteristics of a treated steel plate in a cold tandem rolling device by making the surface roughness of the rolls in the rotating axis direction of work rolls different in the central part and both end parts. CONSTITUTION:In a roll stand having large rolling force in a cold tandem rolling device, large projecting crowns are used and work rolls 4 of which the surface roughness in the rotating axis direction is rough in the central part and fine in both end parts are used. In a roll stand having small rolling force, small projecting crowns are used and further work rolls 4 of which the surface roughness is fine in the central part and is rough in both end parts are used. Then, even if an ordinary rolling mill lubricant is used, the generation of heat streaks is suppressed and the rolling speed can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cold tandem rolling apparatus, and particularly to a cold tandem rolling apparatus which is suitable for cold rolling stainless steel and whose surface properties and productivity are improved.

Traditionally, cold rolling of stainless steel has been carried out to take advantage of the special characteristics of stainless steel, namely that it is a harder material than ordinary steel, and to improve the surface properties that determine the quality of stainless steel products.

It is frequently rolled by a rolling mill with small work rolls (for example, a 20-high roll rolling mill). however.

Usually, such a small diameter roll multi-stage rolling mill Vil stand is often used, and it is necessary to repeatedly roll the material many times to obtain a predetermined finished thickness, resulting in very low production efficiency. In response to this, in recent years, a method has been developed to significantly improve productivity by arranging small-diameter multi-roll mills in tandem and rolling stainless steel with a proportional or cold tandem mill with one ordinary large-diameter roll. ing.

This cold tandem rolling mill generally has a line as schematically shown in No. 1, in which the rolled material 2 is rolled from an unwinding reel 1 to a work roll 4 having a backing roll 5, and then rolled to a take-up reel 3. is wound up. At this time, rolling oil is injected onto the rolling plate 2 or the rolls 4 from a rolling oil header (not shown).

Generally speaking, straight mineral oil is used as a rolling oil for stainless steel, as it has both lubrication and cooling properties to improve the surface gloss, but 5-line rolling oil has a small cooling capacity and a rolling speed of 300 to 400 m/s at most. I can only produce about min. The reason for this is that as the rolling speed increases, the oil film of the rolling oil between the roll and the rolled material breaks due to the rolling turbidity and the temperature rise of the work roll, resulting in surface defects caused by metal contact between the roll and the material. This is thought to be due to the occurrence of heat streaks. (According to past rolling results, it has been found that this heat streak is likely to occur in areas where the rolling pressure is high in the width direction of the rolled plate.) In particular, stainless steel is a material that is prone to heat streaks. Therefore, in order to improve production efficiency by rolling stainless steel at high speed using a tandem rolling mill, a rolling oil with excellent lubrication performance and surface properties is required. However, lubrication performance and surface performance are contradictory properties for rolling oil, and it is extremely difficult to obtain a rolling oil that fully satisfies both of these properties. Therefore, it is necessary to prevent heat streaks when rolling stainless steel using a cold tandem rolling mill. The rolling speed had to be reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cold tandem rolling apparatus that can increase the rolling speed without deteriorating the quality of the surface texture using conventional rolling oil.

The cold tandem rolling equipment of the present invention has a plurality of work rolls for rolling processed steel sheets. #Work roll has a roll surface roughness in the direction of the rotation axis of the roll in the central part. The main feature is that the two ends are different from each other.

Hereinafter, an embodiment of the present invention will be explained in detail with reference to FIG. 3.

The present invention requires rolling using work rolls having different roughness in the direction of the rotational axis, or preferably in combination.
Generally speaking, the rougher the roll surface, the greater the amount of rolling oil drawn between the roll and the material.
As a result, the oil film becomes thicker and the lubricity improves. On the other hand, when the oil film becomes thicker, the material deforms without being constrained by the rolls, and the surface of the material after rolling becomes rough and has poor gloss due to free deformation. In this way, roll surface roughness becomes a factor that has opposite effects on rolling lubricity and surface gloss.

The present invention effectively utilizes the above factors.

A rolled steel sheet with excellent both lubrication performance and surface performance is obtained.

In the present invention, as shown in FIG. 3, the roll surface roughness in the direction of the roll rotation axis is coarse at the center and fine at both ends (FIG. 3(a)), and the roll surface roughness is at the center. The work roll is fine and coarse at both ends (Fig. 3(b) 'I
It is suitable to use them in combination depending on the t- and roll reduction blades.

For example, in a cold tandem rolling machine as shown in FIG. 1, the thickness of the rolling blade is 1, - (1500 to 2000).

2) In the roll stand, a large convex crown is usually used to improve the surface roughness of the stone in the direction of the roll rotation axis as shown in Figure 3 (a).
Use a work roll that is coarse at the center and fine at both ends, as shown in the figure. In addition, the reduction blade is small (1000~1200
) A roll stand usually uses a small convex crown, but also uses a work roll whose surface roughness in the direction of the roll rotation axis is fine at the center and rough at both ends. By arranging the work rolls in this way, in a stand with a large rolling blade, the roll surface roughness is rough in the center of the roll rotation axis where the rolling pressure is high, so the surface gloss tends to deteriorate compared to both ends. However, rolling lubricity is improved, which suppresses the occurrence of heat streaks. −
Since the roll surface roughness is fine at both ends, the rolling lubricity is poor, but since the rolling pressure is lower than at the center, the occurrence of heat streaks can be suppressed here as well.

In addition, even though the roll surface roughness is fine at the center in the direction of the roll axis, the rolling pressure is lower than at both ends, so rolling lubricity improves and surface gloss does not decrease with a stand with a small rolling blade. do not have. - Although the rolling pressure is higher at both ends than at the center, rolling lubricity improves because the roughness is rougher.

Therefore, by arbitrarily arranging such a work roll on the stand of the cold tandem rolling mill of the present invention, it is possible to avoid the complete loss of surface gloss, which is required with conventional rolling oil for stainless steel, and to avoid surface defects. It is possible to increase the rolling speed more than before without generating a certain heat streak.

Table 1 shows heat loss in the conventional method and the method according to the present invention), the presence or absence of IJ-ri, the rolling speed at that time, and the same conditions for surface gloss (inlet side plate thickness).

This shows a comparison in terms of exit side plate thickness). In case (■) of Table 1, the conventional method and the method of the present invention set the rolling reduction ratio and roll crown of each stand to the same conditions]7. In the conventional method, rolls with uniform roughness are used in all the stands, whereas in the method of the present invention, rolls with different roughness are used in the 1st to 4th stands.

The rolling reduction and roll crown of the 7X ζν band are smaller than those of the conventional method. Comparing the conventional method of Case ■ and Case ■, the rolling speed of Case ■ is higher due to the difference in roughness, but on the other hand, the gloss is poorer. Looking at the method of the present invention in case ① and case ②, the rolling speed in case ② is increased by about 30%, but the gloss does not decrease much. As shown in Table 1, it is recognized that the rolling speed of the present invention can increase the rolling speed by about 3 degrees without causing heat streaks.

As described above, according to the present invention, rolling oil conventionally used in cold tandem rolling equipment is used.

It is possible to increase the rolling speed without reducing the surface quality of the steel sheet.

Note that the present invention is applicable depending on the type of rolling oil.

In addition to rolling stainless steel, the present invention is also applicable to thin materials that require high-speed, high-reduction rolling and high-grade surface quality. For example, recently there has been an increase in the number of beer cans and soft drink cans used as products after cold rolling. However, the present invention is directed to steel materials that are made into final products such as beer cans, soft drink steel, or steel treated with electrolytic chromic acid, in which the surface texture after force rolling remains unchanged even after surface treatment. It can also be applied to

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing a general cold tandem rolling apparatus, and FIG. 2 is a diagram illustrating the surface roughness of a conventional rolling work roll. FIG. 3 is a diagram illustrating the surface roughness of the rolling work roll according to the present invention. FIG. ) indicates that the center part in the direction of the roll rotation axis is fine and both ends are coarse. 1... Rewinding reel, 2... Steel plate. 3... Take-up reel, 4... Work roll, 5
°°° Holding roll, X゛0°0° roll axis 1) Fig. 1

Claims (1)

[Scope of Claims] (1) In a cold tandem rolling machine having a plurality of work rolls for rolling treated steel sheets, the work rolls have roll surface roughness in the direction of the rotational axis of the rolls at the center and at both ends. A cold tandem rolling device characterized by being different in: (2. The cold tandem rolling apparatus according to claim 1, characterized in that the roll surface roughness is coarse at the center and fine at both ends. (3) % Scope of Claims The cold tandem rolling apparatus according to claim 1, wherein the roll surface roughness is fine at the center and rough at both ends. (4) Cold rolling according to claim 1. A tandem rolling device is characterized in that the device is equipped with a work roll whose surface roughness is coarse at the center and fine at both ends, and a work roll whose surface roughness is fine at the center and rough at both ends. Device.