JP2008254061A - Method and equipment of cold-rolling steel sheet having improved rolling stability when temper-rolled and cold-rolled steel sheet for use in the same method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling method and the like by which plated steel sheets for cans, of materials different in hardness, elongation, tensile strength or the like can be manufactured for each material and also steel sheets having various surface states can be manufactured for each surface state by making the temper rolling at wide rolling rate possible by eliminating the problem of jumping in wet temper rolling. <P>SOLUTION: When performing the wet temper rolling after tandem cold rolling or reverse cold rolling of the steel sheet, rolling rolls on the surface of which many minute hollows having a diameter of 60-250 μm, a depth of 2-250 μm and a height of swollen part around the hollow of ≤5 μm are formed at the pitch of 80-1,500 μm are used for rolling in the final cold rolling, thereby the rolling stability of the steel sheet when subjected to the wet temper rolling after the cold rolling is improved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for improving rolling stability during wet temper rolling, rolling equipment used in the method, and cold cooling when a steel sheet is temper-rolled through annealing after tandem cold rolling or reverse cold rolling. It relates to rolled steel sheets.

Steel plates for cans such as tinplate to be plated in a subsequent process are given a certain degree of roughness by a dull roll having minute irregularities on the surface in order to improve surface beauty, weldability, and workability.
In addition, steel sheets for cans are made into steel sheets with different materials such as hardness, elongation, tensile strength, etc. by controlling the rolling reduction range in the temper rolling process. Wet temper rolling may be used because the rolling reduction is greater than rolling.

  Since wet temper rolling is performed using a rolling liquid, rolling in a range of about 4% or more, which is commonly referred to as HRT rolling, is possible. When dull rolls are used for wet temper rolling, As a result, the phenomenon of excessive rolling lubrication caused by the rolling fluid being taken into the roll bite and the excessive lubrication due to the increase in friction coefficient due to the dull mountain cannot be controlled at the same time. On the other hand, there is a problem that it is easy to cause a jumping phenomenon that one reduction ratio cannot be determined. For this reason, if the rolling reduction is less than 5%, stable rolling is difficult.

  In order to cope with such a problem, a scratch reduction (bright roll) is conventionally used for wet temper rolling to ensure a stable reduction rate, but since the flat part increases on the surface of the steel plate, the dry type It has a drawback that it has a higher gloss than the surface of the temper rolled material and is not suitable for a tin plate for beverage cans that require a low surface gloss.

  On the other hand, Patent Document 1 discloses that a dull roll having a low surface roughness is used for wet temper rolling to solve the problem of high gloss without causing jumping. Since the color tone of the steel sheet surface changes with the deterioration of the roughness due to the wear of the steel sheet, there is a problem that the gloss in the strip longitudinal direction cannot be stably produced.

JP-A-6-328103 JP 2004-1021 A JP-A-63-10013 JP 2006-167782 A

  In the situation as described above, the present invention can form a plurality of protrusions having a predetermined shape at a predetermined pitch on a steel sheet before temper rolling, even if a scratch roll is used for wet temper rolling. The shape and pattern of protrusions can be inherited even after temper rolling, and the use of scratch rolls as described above may increase the rolling stability during wet temper rolling. We examined the use of dull rolls.

Conventionally, rolling using a dull roll after the tandem cold rolling has been known from, for example, Patent Document 2 and Patent Document 3.
However, the purpose of using dull rolls in each document is to improve the sharpness and workability of the steel sheet surface in Patent Document 2, and in Patent Document 3 to stabilize the plate through such as meandering prevention in continuous annealing. The method for solving the above-mentioned problem in wet temper rolling has not been shown.

  Also, it is known from Patent Document 4 that a dull roll is used in all the stands of tandem cold rolling. In addition, when dull rolls are used in all the stands, there is a problem that transfer patterns are randomly superimposed and a predetermined pattern cannot be obtained.

  Therefore, the present invention eliminates the problem of jumping in wet temper rolling by using a rolling roll having a plurality of holes with a predetermined shape formed on the surface at a predetermined pitch, and temper rolling at a wide rolling rate. A cold rolling method and its equipment, or a temper rolling method using the steel plate obtained by the method and the steel plate obtained by the method, which makes it possible to separately produce steel plates for cans having different materials and surface conditions. It was made as an issue.

The gist of the present invention for solving the above problems is as follows.
(1) In a rolling method of a steel sheet that is wet temper rolled after tandem cold rolling or reverse cold rolling, the final stand of tandem cold rolling or the final pass rolling of reverse cold rolling is applied to the roll surface. Using a rolling roll having a diameter of 60 to 250 μm, a depth of 2.0 to 250 μm, and a plurality of fine holes in which the height of the raised portion around the hole is 5 μm or less arranged in a pitch of 80 to 1500 μm A cold rolling method for a steel sheet, characterized by improving rolling stability during subsequent wet temper rolling.
(2) The cold rolling method according to (1), wherein the rolling reduction of the final stand of tandem cold rolling or the final pass of reverse cold rolling is 1.0 to 40%.

(3) A plurality of protrusions with a diameter of 60 to 250 μm and a height of 2.0 to 95 μm are formed on the surface at a pitch of 80 to 1500 μm by cold rolling in the final stand of tandem cold rolling or the final pass of reverse cold rolling. A cold-rolled steel sheet for wet temper rolling.

(4) A temper rolling method comprising wet temper rolling the cold-rolled steel sheet according to (3) at a rolling reduction of 2.5 to 10%.

(5) In a rolling mill for steel sheets to be wet tempered after tandem cold rolling or reverse cold rolling, the rolling roll in the final stand of tandem cold rolling or the final pass of reverse cold rolling is placed on the roll surface. A plurality of fine holes having a diameter of 60 to 250 μm, a depth of 2.0 to 250 μm, and a height of a raised portion around the hole of 5 μm or less are arranged at a pitch of 80 to 1500 μm. Features cold rolling equipment.

  According to the present invention, the problem of jumping in wet temper rolling can be solved and the rolling stability can be improved, so temper rolling is performed at a wide rolling rate, and materials such as hardness, elongation, tensile strength, etc. Different plated steel plates for cans can be made separately, and a plurality of protrusions of a predetermined shape are formed at a predetermined pitch on the steel plate before temper rolling in advance, so even if scratch rolls are used for temper rolling Steel sheets with various surface states can be made separately. In addition, since a rolling roll having a plurality of holes with a predetermined shape and formed at a predetermined pitch is used, even if the roll surface is worn, protrusions can be stably formed on the steel sheet. Later, a stable and glossy steel plate can be obtained.

Embodiments of the present invention will be described below.
The present inventors have studied the surface shape of a rolling roll that can inherit a rough surface in which a large number of protrusions of a predetermined shape formed by cold rolling are arranged at a predetermined pitch after temper rolling, and can achieve the above-mentioned problem. .

As a result, a steel plate is rolled using a rolling roll that is processed so that a plurality of processing holes of a predetermined shape are regularly arranged in the final roll stand of tandem cold rolling or the final pass of reverse cold rolling. It has been found that rolling can improve rolling stability even if the subsequent temper rolling is wet temper rolling, and can carry over the rough surface formed on the steel sheet after temper rolling.
Here, the rolling roll processed so that a plurality of processing holes are regularly arranged is obtained by dull processing that irradiates the roll surface with a high energy beam such as a laser beam as described in Patent Document 3. This refers to a roll in which processed holes are regularly formed on the surface.

  When the final roll stand of tandem cold rolling or the final pass of reverse cold rolling is cold-rolled using a rolling roll that is laser-dulled so that the processing holes are regularly arranged (ie, a dull roll), the surface of the roll When a dull formed by a large number of processed holes is transferred to the surface of the steel plate, the portion without the processed holes on the surface of the steel plate remains as a flat portion as it is. Profile changes can be reduced.

  On the other hand, the surface of the roll dulled by means such as shot blasting or electric discharge machining is a rough surface having irregular irregularities with almost no flat part, and a steel plate formed by such a roll. The upper concave portion is easily crushed in the next temper rolling, and the steel sheet roughness cannot be inherited as it is after the temper rolling.

FIG. 1 schematically shows a part of the surface of the rolling roll used for the final roll stand of tandem cold rolling or the final pass of reverse cold rolling, and FIG. 2 shows a part of the cross section of the surface. Shown in
The processed holes 2 regularly arranged on the surface of the rolling roll 1 have a hole diameter (hole diameter) 3 in the range of 60 to 250 μm, a hole depth 4 in the range of 2.0 to 250 μm, and a hole pitch. (Distance between centers of processed holes) 5 needs to be arranged in a range of 80 to 1500 μm. Further, when the hole is processed, the swelled portion 6 may be formed around the hole. In this case, the height 7 is set to 5 μm or less.

The reason why the hole diameter is so determined is that when the hole diameter is less than 60 μm, the hole diameter is too small to obtain a sufficient effect. When the hole diameter exceeds 250 μm, the transfer mark of the processed hole to the steel plate is clearly visible to the naked eye. This is because the appearance can be discriminated and the appearance is not suitable. The hole is preferably circular, but if it is not circular, the average value of the major and minor diameters is taken as the diameter of the hole.
The depth of the processed hole is determined as such, and if the height is less than 2.0 μm, the protrusion height of the steel sheet becomes less than 2.0 μm, and the coefficient of friction during temper rolling can be secured. This is because rolling is not stable and, on the other hand, if it exceeds 250 μm, the fatigue strength of the roll surface is lowered, and a roll surface defect accident tends to occur.

  Further, the reason why the pitch (center-to-center distance) of the processing holes is determined in this way is that when the number is 1500 μm or more, the number of holes is too small to obtain a sufficient effect. This is because a moire pattern is generated on the surface of the steel plate, and the probability that the product is unacceptable in appearance increases. The hole pitch is preferably the same in the circumferential direction and the width direction of the roll, but is not necessarily the same as long as it is in the above range. The hole area ratio is preferably 0.19 to 78.5%.

  If the height 8 of the raised portion around the hole is 5 μm or less, if it exceeds 5 μm, the pattern formed by the raised portion at the time of cold rolling remains on the steel plate surface even after temper rolling, This is because it is not preferable in appearance.

  By rolling using the dull roll described above in the final stand of tandem cold rolling or the final pass of reverse cold rolling, the dull eyes due to the processed holes in the roll are transferred to the surface of the steel sheet, and protrusions are formed on the entire surface of the steel sheet. A rough surface is formed. In order to do so, the rolling reduction is preferably 1.0 to 40%. If it is less than 1.0%, a sufficiently large protrusion cannot be formed on the steel plate, and if it exceeds 40%, the shape of the steel plate becomes poor.

By performing rolling in the final stand of tandem cold rolling or the final pass of reverse cold rolling using the rolling roll described above, as shown in FIG. 3, a steel plate having protrusions formed on the surface at a predetermined pitch is obtained. can get.
The diameter and pitch of the projections 9 of the steel plate 8 are the same as the diameter and pitch of the processing holes of the roll, the diameter 10 is 60 to 250 μm, and the pitch is 80 to 1500 μm. Moreover, the height 11 of the protrusion of the steel plate is 2.0 to 95 μm.
The reason why the height of the protrusions of the steel sheet is set in such a range is that if it is less than 2.0 μm, the friction coefficient in temper rolling cannot be increased, and the effect of rolling stabilization cannot be enjoyed. This is because the pattern remains after temper rolling and is not preferable in appearance.

  If the steel plate with protrusions formed in this way is rolled using a scratch roll in the next wet temper rolling, the problem of jumping in the wet temper rolling is eliminated, and a wide rolling reduction of 2.5 to 10%. Therefore, various steel sheets for cans having different materials such as hardness can be made separately.

  In addition, since the above-mentioned dull stitches are formed on the steel plate before temper rolling, even if scratch rolls are used for temper rolling, temper rolling can be performed without crushing the galling, so tandem cold rolling By adjusting the shape and pitch of the processed holes on the surface of the rolling roll used in the final roll stand or the final pass of reverse cold rolling, steel sheets having various surface states can be made separately. Also, since rolls that are dulled so that the processing holes are regularly arranged are used, even if the roll surface is worn, the surface shape of the roll remains unchanged if the processing holes have a sufficient depth. Since it is held, a dull eye can be formed stably on the steel sheet, and as a result, a stable glossy steel sheet can be obtained after temper rolling.

  Examples of the present invention will be described below. However, the conditions adopted in the examples are conditions for confirming the feasibility and effects of the present invention, and the present invention is limited to these conditions. However, various conditions can be adopted as long as the object of the present invention is achieved without departing from the present invention.

The hot-rolled steel sheet for cans prepared by a normal method was tandem cold-rolled and wet-tempered after continuous annealing. In the final stand of tandem cold rolling, the hole diameter is 100μm, the hole depth is 50μm, and the height of the raised part is 5μm or less so that the holes are regularly arranged at a pitch of 500μm (area ratio 3.14%) The processed laser dull roll was used to form a rough surface in which protrusions having flat top portions were regularly formed on both surfaces of the steel plate.
Wet temper rolling was performed using a two-stand rolling mill, using a scratch roll in the first stand and a bright roll in the second stand at a reduction rate of 3.8%.
As a result, a steel sheet having a hardness of 60 and a surface roughness of Ra 0.38 μm was obtained without occurrence of jumping.

Also, wet temper rolling was performed in the same manner for the final stand of tandem cold rolling without rolling a dull roll.
As a result, when the laser dull roll was not used, jumping occurred at a rolling reduction of 4.5%.

In Example 1, the hole diameter, hole depth, and hole pitch of the laser dull roll used in the final stand of the tandem cold rolling (the height of the raised portion is 5 μm or less), the rolling conditions of the final stand, Cold-rolled steel sheets were obtained by changing the rolling reduction ratio of wet temper rolling.
The obtained results are shown in Tables 1 and 2. From Tables 1 and 2, it can be seen that in the examples according to the present invention, steel sheets having various surface states can be obtained without causing jumping. On the other hand, in the comparative example, it can be seen that jumping may occur or a steel sheet having a preferable surface state may not be obtained.

It is a figure which shows typically a part of rolling roll with which several fine holes were formed in the surface. It is sectional drawing which shows the hole formed in the roll surface. It is sectional drawing of the steel plate rolled with the roll shown to FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Roll roll 2 Processed hole 3 Hole diameter (hole diameter)
4 Hole depth 5 Hole pitch 6 Swelling part 7 Swelling part height 8 Steel plate 9 Protrusion formed on steel plate 10 Protrusion diameter 11 Protrusion height

Claims (5)

In tandem cold rolling or reverse cold rolling, in the cold rolling method of the steel sheet to be wet temper rolled,
The final stand of tandem cold rolling or the final pass of reverse cold rolling is rolled onto the roll surface with a diameter of 60 to 250 μm and a depth of 2.0 to 250 μm, and the height of the raised portion around the hole is Cold rolling of a steel sheet characterized in that rolling stability during subsequent wet temper rolling is enhanced by using a rolling roll in which a plurality of fine holes of 5 μm or less are arranged at a pitch of 80 to 1500 μm. Rolling method.   The method for cold rolling a steel sheet according to claim 1, wherein the rolling reduction of the final stand of tandem cold rolling or the final pass of reverse cold rolling is 1.0 to 40%.   By cold rolling in the final stand of tandem cold rolling or the final pass of reverse cold rolling, a plurality of protrusions having a diameter of 60 to 250 μm and a height of 2.0 to 95 μm are formed on the surface at a pitch of 80 to 1500 μm. A cold-rolled steel sheet for wet temper rolling.   A temper rolling method comprising subjecting the cold rolled steel sheet according to claim 3 to wet temper rolling at a rolling reduction of 2.5 to 10%. In cold rolling equipment for steel sheets to be wet temper rolled after tandem cold rolling or reverse cold rolling,
The rolling roll in the final stand of tandem cold rolling or the final pass of reverse cold rolling has a diameter of 60 to 250 μm and a depth of 2.0 to 250 μm on the roll surface, and the height of the raised portion around the hole A cold rolling facility, wherein a plurality of fine holes having a pitch of 5 μm or less are arranged at a pitch of 80 to 1500 μm.

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