KR102371055B1 - Cold rolling method of metal strip - Google Patents

Abstract

When rolling a metal strip using a multi-rolling machine having at least a pair of top and bottom work rolls, a pair of top and bottom intermediate rolls, and a pair of top and bottom backup rolls, at least one intermediate roll is reciprocally moved in the roll axis direction, preferably Preferably, the position of the intermediate roll end is within the range of 30 mm inward and 80 mm outward from the wide end of the metal band, the stroke is within the range of 5 to 60 mm, and the movement speed is set within the range of 0.5 to 4.0 mm/sec. A method of rolling a metal strip that effectively prevents the occurrence of plate marks by rolling while reciprocating, without attaching special equipment to the rolling mill, and without causing a decrease in productivity or an increase in manufacturing cost.

Description

Cold rolling method of metal strips {COLD ROLLING METHOD OF METAL STRIP}

The present invention relates to a method of cold rolling a metallic band, and more particularly, to a method of cold rolling a metallic band having excellent surface properties.

For example, as a rolling mill used for cold rolling of a metal strip (metal strip) such as a steel sheet, various types of rolling mills have been put to practical use. A quadruple (4Hi) rolling mill having a pair of upper and lower backup rolls, a six-fold (6Hi) rolling mill in which a pair of upper and lower intermediate rolls are provided between the upper and lower work rolls and the backup roll, etc. are common.

With a rolling mill having a pair of upper and lower work rolls and a backup roll as described above, when a metal strip of the same width is continuously rolled for a long time, the part in contact with the metal strip as a material to be rolled (generally, “rolling trace) wears out, and in particular, the surface of the work roll at the part in contact with the wide end of the metal band is worn out abnormally, and the shape or level difference called a "rolling trace mark" on the roll surface occurs When a metal strip having a wider width than before is rolled using the work roll on which the plate mark is formed, the plate mark generated on the surface of the work roll is transferred to the surface of the metal strip after rolling, causing surface defects.

However, since the work roll is directly related to the surface quality of the product, it is replaced in a short period of time, and its replacement is also relatively easy, so the influence on the product quality is relatively small. However, the plate mark generated on the surface of the work roll is also transferred to the backup roll. A backup roll is generally used continuously for a long period of time, and its replacement is not easy, and a long-term line stop is required. Therefore, also in a backup roll, the request|requirement with respect to the technique which prevents a board mark is large. In addition, the plate mark can be generated in any cold rolling mill (rolling stand) including temper rolling, if it is a multi-stage (multi-stage) rolling mill.

As a technology for preventing plate mark, the rolling equipment relates to, for example, Patent Document 1, in a cold tandem rolling mill equipped with a circulating oil supply mechanism for emulsion rolling oil, a nozzle header for spraying emulsion rolling oil to a backup roll is provided And, when spraying the emulsion rolling oil from the nozzle header to the backup roll, by spraying with vibration in the megahertz band, the circulating emulsion itself as a grinding medium A method of grinding the plate mark formed on the backup roll This is proposed.

Further, Patent Document 2 proposes a backup roll grinder for cold rolling that grinds the roll surface on-line by pushing a rotating grindstone to the rotating roll while rotating the rolling roll in a state incorporated in the rolling mill. In addition, as a technology for preventing plate marks in hot rolling, Patent Document 3 provides an on-line roll grinder for grinding the work rolls by moving in the width direction of the material to be rolled with respect to the upper and lower work rolls, and the grinder is applied to the material to be rolled. A method of moving in point symmetry with respect to the center of gravity has been proposed.

On the other hand, as a plate mark prevention technique when cold rolling a metal strip using a tandem cold rolling mill, a dull roll having a rough surface roughness is used for the work roll, and rolling is performed at a remarkably low reduction ratio. , a technique for minimizing abnormal wear of a work roll at a metal to end portion is known. In addition, in the 4Hi rolling machine composed of a pair of work rolls and a pair of backup rolls, the line is stopped before rolling a material with a width wider than the plate mark position, and the backup roll and the work roll are removed with the roll bite open. There is also known a method of grinding a board mark transferred to a backup roll by rotating it for a certain period of time in a contact state.

Japanese Laid-Open Patent Publication No. 2010-162546 Japanese Laid-Open Patent Publication No. 2006-055895 Japanese Laid-Open Patent Publication No. 2003-300134

However, in the methods disclosed in Patent Documents 1 to 3 described above, special equipment other than the cold rolling mill is required, such as a device that excites the sprayed emulsion rolling oil with vibration in the megahertz band, or an online grinder device. Therefore, there is a problem that not only the equipment cost but also the maintenance load increase. In addition, in the method of rolling at a low reduction ratio using a Dull roll in the work roll, or in the method of grinding the plate mark by revolving in a state in which the backup roll and the work roll are in contact, there is a problem that productivity decreases and manufacturing cost increases. there is.

The present invention has been made in view of the above problems of the prior art, and its object is to produce a plate mark without attaching special equipment to the rolling mill, and without causing a decrease in productivity or an increase in manufacturing cost. It is to propose the rolling method of the metal strip which can prevent generation|occurrence|production effectively.

The inventors repeated earnest examination in order to solve the said subject. As a result, the metal strip is rolled using a rolling mill of 6Hi or more having at least one pair of work rolls, a pair of intermediate rolls and a pair of backup rolls, and having a shift function capable of moving the intermediate roll in the direction of the roll axis. In this case, by automatically reciprocating the intermediate roll in the direction of the roll axis, it is possible to significantly reduce the transfer of the plate mark to the backup roll, and also to grind the plate and mark transferred to the backup roll. developed an invention.

The present invention based on the above recognition is a method for cold rolling a metal strip using a rolling mill having at least a pair of top and bottom work rolls, a pair of top and bottom intermediate rolls, and a pair of top and bottom backup rolls, at least one of A method of cold rolling a metal strip is proposed, characterized in that the metal strip is rolled while the intermediate roll is reciprocally moved in the roll axis direction.

The cold rolling method of the metal strip of the present invention is characterized in that the position of the roll end of the intermediate roll is reciprocated within a range of 30 mm inward and 80 mm outward from the wide end of the metal strip.

Moreover, in the cold rolling method of the metal strip of this invention, the stroke of the reciprocating movement of the said intermediate|middle roll shall be made into the range of 5-60 mm, It is characterized by the above-mentioned.

Moreover, the cold rolling method of the metal strip of this invention sets the moving speed of the reciprocating movement of the said intermediate|middle roll to 0.5-4.0 mm/sec, It is characterized by the above-mentioned.

Further, the cold rolling method of the metal strip of the present invention is characterized in that the pair of intermediate rolls are reciprocated in opposite directions to each other.

According to the present invention, by automatically reciprocating the intermediate roll in the direction of the roll axis during the rolling of the metal strip, the transfer of the board mark from the work roll to the back-up roll can be significantly reduced, and at the same time, the board mark transferred to the back-up roll can be reduced. A grinding effect is obtained. Therefore, according to the present invention, a metal base product with a good surface quality can always be produced without requiring special auxiliary equipment for the rolling mill and without causing adverse effects on productivity accompanying a long rolling line stop. it becomes possible to obtain

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structural example of the apparatus in this invention.
It is a figure which shows the situation at the time of the relative movement to the axial direction movement of the intermediate|middle roll in this invention.
It is a figure explaining the pattern when an intermediate|middle roll reciprocates.

(Form for implementing the invention)

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated concretely.

First, the present invention is a technique for preventing the transfer of the board mark to the back-up roll by reciprocating the intermediate roll in the roll axis direction, and reducing and removing the board mark by grinding the back-up roll surface. Accordingly, the cold rolling mill used in the present invention for rolling a metal strip has at least a pair of top and bottom work rolls, a pair of top and bottom middle rolls, and a pair of top and bottom backup rolls, and moves the intermediate rolls in the roll axis direction. It is necessary to have a multi-rolling mill of 6Hi or higher with a shift function that can make 1 shows, as an example, a pair of top and bottom work rolls 1 and 1 ′, a pair of top and bottom intermediate rolls 2 and 2 ′, and a pair of top and bottom backup rolls 3 that can be used in the present invention as an example. , 3'), and is a schematic diagram showing a 6Hi rolling mill having a shift function capable of moving (shifting) the intermediate rolls 2 and 2' in the roll axis direction. In addition, the said rolling mill may be a single rolling machine which consists of a stage stand, or a tandem type rolling machine which consists of a plurality of stands may be sufficient as it.

Further, in the cold rolling method of the metal strip of the present invention, the roll end of the intermediate roll is reciprocated within the range of 30 mm inward (side in the sheet width center direction) and 80 mm outward (opposite to the inner side) from the wide end of the metal strip. It is preferable to move It is because rolling can be performed without exerting a bad influence on the shape of the metal strip after rolling if it is a movement of an intermediate|middle roll within this range. Preferably it is in the range of 10 mm inward and 60 mm outward. Here, the roll end of the intermediate roll refers to the long end of the intermediate roll literally as shown in Fig. 2(a) when the intermediate roll is a flat roll, and when the intermediate roll is a tapered roll is, as shown in Fig. 2(b), a boundary portion (shoulder portion) between the flat portion and the tapered portion.

In addition, as shown in FIG. 3, the pattern when the said intermediate roll reciprocates, (a) a sine wave pattern, (b) a triangular wave pattern, (c) a trapezoidal wave pattern, (d) a (stepped wave+triangle wave) pattern, etc. Any pattern may be used, but from the viewpoint of stabilizing the shape of the metal strip after rolling and stabilizing the rolling load, it is most preferable to adopt the (step wave + triangular wave) pattern of (d).

In addition, as described above, it is preferable that the roll end of the intermediate roll reciprocate within a range of 110 mm of 30 mm inward and 80 mm outward from the wide end of the metal band, but within the range of the intermediate roll The stroke in the axial direction (in the case of the pattern (d), the amount of movement per step) is preferably in the range of 5 to 60 mm. If the movement amount is less than 5 mm, the effect of preventing plate slip is small. On the other hand, if it exceeds 60 mm, a bad influence occurs on the shape of the metal strip after rolling, causing shape defects such as corner extension (end extension). Because. More preferably, it exists in the range of 10-30 mm.

Moreover, when reciprocating the said intermediate|middle roll in the roll axis direction, it is preferable that a moving speed shall be 0.5-4.0 mm/sec regardless of whether a rolling speed is a low speed and a high speed. When the moving speed is less than 0.5 mm/sec, the effect of preventing the plate is small. On the other hand, when it exceeds 4.0 mm/sec, a sharp change occurs in the shape of the metal strip after rolling, which causes rolling troubles such as drawing. am. More preferably, it exists in the range of 1.0-2.0 mm/sec.

Further, in the cold rolling method of the present invention, only the upper intermediate roll or only the intermediate roll among the pair of upper and lower intermediate rolls may be reciprocally moved in the roll axis direction. It is preferable to reciprocate simultaneously and in the opposite direction to each other.

In addition, when the cold rolling method of the present invention is applied to a tandem cold rolling mill, it is preferable to apply it to a rear end stand, for example, in the case of a 5 stand tandem cold rolling mill, #4 and/or #5 It is desirable to apply to the stand. This is because it is the rear end stand that has a great influence on the surface quality of the product, and there are many examples in which multiple rolling mills having intermediate rolls are installed on the rear end stand.

Example 1

The present invention is applied to the #4 stand of a tandem cold rolling mill composed of 5 stands and equipped with a 6Hi rolling mill having an intermediate roll on the #4 stand, and hot rolling with a plate thickness: 2.0 to 7.0 mm × plate width: 762 to 1880 mm An experiment of cold-rolling a steel plate to the final plate|board thickness: 0.5-3.3 mm was done. Table 1 shows the rolling conditions at this time.

At this time, the length of the steel sheet on the exit side of the #5 stand during the 10 mm movement of the intermediate roll, that is, the rolling length at the #5 stand, was variously changed from 100 m to 400 m, and the plate generated on the surface of the steel sheet after rolling The occurrence situation of the mark was evaluated. Moreover, the board|boarding mark was evaluated also about the case where an intermediate roll is not made to reciprocate.

Here, the plate mark was evaluated by visually observing the surface of the steel plate on the #4 stand and the steel plate on the exit side of the #5 stand over a length of 30 m, and evaluated according to the following criteria. In addition, in this invention, the board mark made (circle) and (triangle|delta) into the "pass" range.

energy

○: No transfer of board mark (No board mark was confirmed on the surface of the steel plate on the exit side of #4 and #5 stands)

△: There is slight transfer of the plate mark (transfer is confirmed on the surface of the steel plate on the exit side of stand #4, but no transfer is confirmed on the surface of the steel plate on the exit side of stand #5)

×: A plate mark is generated (transfer is confirmed on the surface of the steel plate on the exit side of stand #4, and transfer is also confirmed on the surface of the steel plate on the exit side of stand #5)

The above evaluation results are shown in Table 2 below. From this result, when the rolling length at the final stand between moving the intermediate roll by 10 mm was in the range of 100 to 300 m, transfer of the plate mark to the surface of the steel sheet was not confirmed, and good surface quality was always obtained. In addition, by being able to prevent transfer of the plate mark to the surface of the steel plate, the frequency of replacement of the work roll, the intermediate roll, and the backup roll was reduced.

Example 2

In the above embodiment 1, within the range of 100 to 300 m in rolling length in the final stand between moving the intermediate roll by 10 mm, the strokes of the intermediate roll of the #4 stand were 2 mm, 30 mm and 80 mm. Changed in three steps, and the other rolling conditions were as shown in Table 1, and the same hot-rolled steel sheet as in Example 1 was cold-rolled. The condition and the shape of the steel plate on the exit side of the rolling mill were evaluated.

Here, the plate also marks were evaluated according to the evaluation criteria of Example 1, and the steel plate shape was evaluated according to the following criteria. In addition, in this invention, the steel plate shape made (circle) and (triangle|delta) into the "pass" range.

energy

○: Good shape (the difference in steepness in the plate width direction is less than 0.3%)

△: Corner extension (short extension) slight (the difference in steepness in the plate width direction is 0.3 to 0.5%)

×: Corner extension (short extension) occurred (the difference in steepness in the plate width direction exceeds 0.5%)

Table 3 shows the results of the above measurements. From this table, it can be seen that, as long as the stroke of the intermediate roll is within the range of the present invention, the occurrence of plate marks can be prevented without impairing the shape of the steel plate after rolling.

Example 3

Similar to Example 1, an experiment was conducted in which a hot-rolled steel sheet having a sheet thickness of 2.0 to 7.0 mm × sheet width: 762 to 1880 mm was cold rolled to a final sheet thickness of 0.5 to 3.3 mm. At this time, the cold rolling conditions are based on the conditions shown in Table 1, the moving range of the intermediate roll end part, the moving speed of the intermediate roll, and the intermediate roll to be moved are changed as shown in Table 4, and the intermediate roll is changed to 10 The rolling length in the final stand between moving mm was varied in the range of 100 to 300 m. Then, about the steel plate after the said cold rolling, about the generation|occurrence|production level of a plate|board also mark and the steel plate shape, the criteria similar to the above-mentioned Examples 1 and 2 were evaluated.

The said evaluation result was written together in Table 4. From this result, even under any of the above rolling conditions, both the plate mark and the steel plate shape were within the allowable ranges, but the moving range of the intermediate roll end was -30 mm to +80 mm, and the moving speed of the intermediate roll was 0.5 to 4.0 mm/sec. In the range of , and under the conditions of moving the upper and lower intermediate rolls, the best plate also mark level and steel plate shape were obtained.

1: Upper work roll
1' : ha work roll
2: Upper middle roll
2' : Roll between loads
3: Phase backup roll
3' : lower backup roll
4: metal strip (metal strip)

Claims (5)

A method of cold rolling a metal strip using a rolling mill having at least a pair of top and bottom work rolls, a pair of top and bottom intermediate rolls, and a pair of top and bottom backup rolls, the method comprising:
Metal characterized in that the metal strip is rolled while reciprocating the position of the roll end of at least one of the intermediate rolls within the range of 30 mm inward and 80 mm outward from the width end of the metal strip in the roll axis direction. stand cold rolling method. According to claim 1,
The cold rolling method of the metal strip characterized by making the stroke of the reciprocating movement of the said intermediate roll into the range of 5-60 mm. 3. The method of claim 1 or 2,
The cold rolling method of a metal strip, characterized in that the moving speed of the reciprocating movement of the intermediate roll is 0.5 to 4.0 mm/sec. 3. The method of claim 1 or 2,
A method for cold rolling a metal strip, characterized in that the pair of intermediate rolls are reciprocally moved in opposite directions to each other. 4. The method of claim 3,
A method for cold rolling a metal strip, characterized in that the pair of intermediate rolls are reciprocally moved in opposite directions to each other.

Images