JPH05138221A - Method for shifting work roll at the time of rolling - Google Patents

Abstract

PURPOSE:To uniformize dispersion of thermal crown and wear of work roll at the time of continuous rolling by shifting work rolls in a state where the axial center of back-up roll is inclined to the axial center of work roll on the horizontal plane. CONSTITUTION:In the arrangement of a work roll 2 and buck-up roll 1 on the horizontal plate at the time of rolling, the back-up roll 1 is inclined to the work roll 2 on the horizontal plane at the time of rolling so that one end part of the back-up roll which is situated in the direction to which the work roll 2 is desired to be shifted is directed to the outlet side of the rolling mill with respect to the other end part and a shifting force is added. Since a thrust force acts on the work roll 2 toward that direction and frictional resistance is reduced by the amt. of thrust force in the case of shifting in that direction, small shift is enabled. And meandering of the rolled stock isn't generated and stable rolling is enabled even when the work roll 2 is shifted at the time of rolling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work roll shifting method during rolling. More specifically, the present invention, in particular, joins the preceding rolled material and the trailing rolled material on the entry side of the finishing rolling mill row of hot rolling, and continuously supplies the rolling material to the finishing rolling mill row to generate heat. The present invention relates to a work roll shifting method during rolling, in which a work roll is shifted in the axial direction during rolling when a continuous rolling method in which hot rolling is performed.

[0002]

2. Description of the Related Art Conventionally, a hot-rolled steel strip is roughly finished by rolling a slab with a weight of about 30 tons and then a finishing rolling mill consisting of 6 to 7 stand rolling mills with a minimum strip thickness of 1.2 mm. It was manufactured by a non-continuous rolling method for each coil, in which hot rolling was performed to a certain degree, further cooling to a predetermined temperature with a hot run table, and then winding into a coil by a down coiler. In this discontinuous rolling method, finish rolling, which has a great influence on the quality of the hot-rolled steel strip, has been performed by a tandem rolling mill having a plurality of stands.

By the way, in order to prevent the rolling trouble at the tip of the rolled material at the time of finish rolling from occurring, it is necessary to prevent the occurrence of rolling troubles due to the defective shape of the tip such as meandering, camber, rising nose and descending nose. I had to do it in.
For this reason, the temperature of the tip during rolling is lowered, not only the mechanical properties of the hot-rolled steel strip obtained are deteriorated, but also the plate thickness of the rolled material, the plate crown, and the flatness are deteriorated. There was a problem that it would end up. This problem has been particularly noticeable in thin and wide strips, which are in great demand, but as mentioned above, in the past, measures were taken to perform rolling at a low speed in order to prevent the occurrence of defective shape at the tip of the strip. Other than that, there was a problem that the yield and rolling efficiency were extremely low.

In order to solve this problem, the trailing end of the preceding rolled material and the leading end of the trailing rolled material are joined by welding or the like between the rough rolling mill and the finish rolling mill to continue the finish rolling. A finishing continuous rolling method has been proposed. This finishing continuous rolling method is, in brief, joined by a joining machine to integrate the trailing end portion of the preceding rolled material and the leading end portion of the trailing rolled material before performing the finishing rolling into a continuous, i.e., joined portion. When passing through a rolling mill, the rolling speed is not significantly reduced, finish rolling and cooling with a hot run table are performed to cool to a specified temperature, and then these two types of rolled materials are cut and divided with a flying shear. Then, the preceding rolled material and the following rolled material are branched into different down coilers and wound up.

However, in the above-mentioned finishing continuous rolling method, as compared with the discontinuous rolling method, about 5 or more rolled materials in the discontinuous rolling method, or about 10 minutes or more in terms of time, are continuously rolled. If this is not done, the manufacturing cost will rather increase due to the increased cost required for joining. Therefore, it is necessary to perform the finish rolling continuously for at least about 10 minutes, but for this reason, it was not possible to reduce and uniform the thermal crown and wear of the work roll.

That is, in the conventional discontinuous rolling method, the rolling time per rolled material is about 3 minutes at the most, so that the non-existence between the rolling of the preceding rolling material and the rolling of the following rolling material. By cooling the work rolls or shifting the work rolls in the axial direction during the rolling time, the thermal crown and roll wear generated by the temperature rise of the work rolls are reduced or made uniform, and the plate profile of the product after rolling is reduced. It was possible to prevent deterioration of the shape.

However, in the continuous rolling method, since the non-rolling time cannot be secured, the above-described roll cooling and work roll shift cannot be performed, and thermal crown and wear of work rolls can be reduced and uniformed. It is impossible. Therefore, the continuous rolling method actually causes rolling troubles due to abnormal profile of the product or defective shape, so that there is a limit to the number of rolled materials that can be continuously rolled, and the continuous rolling method is At present, the objective improvement of yield and rolling efficiency has not been achieved sufficiently.

[0008]

In the continuous rolling method, in order to prevent thermal crown of work rolls, abnormal plate profile due to wear, and defective shape, work is performed at the time of rolling as in the discontinuous rolling method. By shifting the roll in the axial direction, it is possible to disperse a rapid thermal crown change and local wear in the vicinity of the end in the plate width direction so that the work roll profile approaches a quadratic curve distribution. There is no end. If the profile of the work roll changes in a form close to a quadratic curve distribution,
This is because the profile and shape of the rolled material can be controlled to be constant by using a conventional crown control means such as a work roll bender.

However, the shift of the work roll in the axial direction in the discontinuous rolling method is carried out during non-rolling as described above, and not during rolling. When this is done during rolling, the thrust resistance due to rolling load is extremely large and a very large shift force is required, but due to the mechanical constraints of the work roll itself, especially the lack of strength of the shaft neck of the work roll, This is because it is practically impossible to shift the work roll in the axial direction during rolling.

Therefore, in the continuous rolling method, in order to realize the shift of the work roll in the axial direction during rolling, the shift resistance due to the rolling load is reduced so that even a small shift force can be easily performed in the axial direction of the work roll. It is necessary to establish technology that enables shifts.

An object of the present invention is to make it possible to easily shift the work rolls in the axial direction during rolling in order to evenly disperse the thermal crown and wear of the work rolls during continuous rolling. It is to provide a work roll shift method.

[0012]

In order to shift the work rolls in the axial direction during rolling by a normal multiple rolling mill, the work rolls are provided with friction resistance between the rolled material and the work rolls, the work rolls and the work rolls. A shift force sufficient to overcome the wear resistance between the backup rolls in contact with the rolls must be applied.Especially in hot rolling, the friction resistance between the rolled material and the work rolls is large, and a very large shift force is required. Become. FIG. 2 shows a conventional quadruple rolling mill. In FIG. 2, the axis of the backup roll 1 and the axis of the work roll 2 were arranged parallel to each other in a plane substantially perpendicular to the rolling direction. In the rolling mill of this structure, in order to shift the work roll 2 in the axial direction during rolling, it is necessary to apply a shift force equal to or greater than the frictional resistance due to the rolling load, which is about 20% of the rolling load. It is a great power. Therefore, due to the strength of the work roll, in reality, it was impossible to shift the work roll in the axial direction during rolling. In the figure, 3
Is a rolled material.

However, as a result of further study by the present inventor, when the rolling is performed in a state in which the backup roll is inclined so that the axis of the backup roll intersects with the axis of the work roll in the horizontal plane, rolling is performed. A thrust force in the axial direction is applied to the work roll from the backup roll. The acting direction of the thrust force is from the inlet side of the rolling mill of the two end portions of the backup roll that is inclined. The present invention has been completed by finding that it is a direction toward the exit side of the rolling mill, and further, if the work roll is shifted in the direction, the shift force of the work roll is significantly reduced by the thrust force. ..

Here, the gist of the present invention is a work roll shifting method during rolling, in which a work roll supported by a backup roll is shifted in the axial direction of the work roll during rolling. The end of the backup roll located on the side to be shifted is on the rolling mill delivery side with respect to the other end, so that the axis of the backup roll is in the horizontal plane with respect to the axis of the work roll, Is a work roll at the time of rolling characterized in that the work roll is shifted in a tilted state so that the axis of the backup roll and the axis of the work roll intersect at the barrel center of the backup roll. It is a shift method.

Since the thrust force acting on the work roll increases in accordance with the rolling load and the crossing angle of the shaft core, by providing an appropriate crossing angle according to the rolling conditions, even during rolling with a small shift force. Work roll shift is possible.

In the practice of the present invention, the pair of upper and lower work rolls of the same rolling mill are shifted in opposite directions, so that the symmetric property of the rolled material profile can be ensured. Furthermore, in order to apply the present invention to a tandem rolling mill comprising a plurality of rolling mills, upper work rolls of adjacent rolling mills, and lower work rolls of the rolling mills may be shifted in opposite directions, for the same reason. ,desirable.

[0017]

The operation of the present invention will be described in detail below. In the present invention, as shown in FIG. 1 which schematically shows the arrangement of the work rolls and the backup rolls on the horizontal plane during rolling, the backup rolls 1 are shifted from the work rolls 2 on the horizontal plane during rolling. The backup roll located in the desired direction (the same direction as the white arrow in FIG. 1) is inclined and a shift force is applied in that direction so that the end of the backup roll is on the delivery side of the rolling mill with respect to the other end.

Then, since a thrust force acts on the work roll 2 in the direction, the frictional resistance is reduced by the thrust force when the work roll 2 is shifted in this direction. It is possible to shift work rolls during rolling. As shown in FIG. 3, the work roll shift force required to shift the work rolls during rolling is set so that the cross angle θ in FIG.
It decreases as it gradually increases from 0 °, and greatly decreases when θ = 3 °.

The data shown in FIG. 3 is the case of hot rolling with a quadruple rolling mill having a work roll diameter of 200 mm and a barrel length of 400 mm, which is generally used for the production of hot rolled steel strip. For a rolling machine with a work roll diameter of 800 mm and a barrel length of 2000 mm, a shift force of about 10 times this result is required.
When the cross angle θ is 0 °, it is impossible to shift the work roll during rolling only when the rolling load is 1000 tons or less due to the strength of the work roll. = 3 °, the work rolls can be shifted even with a rolling load of 2000 tons, and the effect of the present invention is very large. From the viewpoint of reducing the shift force, a cross angle θ of 0.1 ° is sufficient to obtain the effect.
If the rolling angle exceeds 3.5 °, the thrust force becomes too large, and in the case where the rolling load is large, the shift amount cannot be controlled unless a reverse shift force is applied. Therefore,
The desirable range of the cross angle θ is 0.1 to 3.5 °.

In the present invention, the work rolls may be shifted at any time during rolling, and there is no particular limitation. For example, the hot rolling steel strip may be continuously rolled for about 10 minutes by the finishing continuous rolling method. When carrying out, it is desirable to carry out a work roll shift of 30 mm at least once every 3 minutes. Further, the backup roll may be tilted only during the shift, or may be tilted during rolling other than the shift and may be shifted by applying a shift force only during the shift. Further, in the case where the continuous rolling time becomes long, when the shift stroke end is reached, the inclination direction of the backup roll may be reversed and the shift may be performed in the opposite direction again.

In the present invention, the intersection of the axis of the work roll and the axis of the backup roll is preferably the center of the barrel of the backup roll 1, as shown in FIG. This is because if the cross angle θ is increased to the extent that the present invention is implemented, the plate crown is likely to change, so it is desirable to intersect at the barrel center of the backup roll because of the lateral symmetry of the plate profile. Further, when the intersection is shifted to the left and right, the rolled material meanders, so it is desirable to intersect at the center of the barrel from the viewpoint of the stability of the strip.

It is desirable that the shift directions of the pair of upper and lower work rolls of the same rolling mill are opposite to each other in order to ensure the lateral symmetry of the plate profile. That is, when the material is shifted in the same direction and rolled at a barrel end portion having a small thermal crown, the strip thickness of the rolled material is partially thinned, and the strip thickness becomes uneven in the strip width direction. Further, if the material is shifted in the same direction, the rolled material tends to meander in the shifted direction. Therefore, it is desirable to shift the upper and lower work rolls in opposite directions from the viewpoint of the stability of the threaded strip.

For the same reason, in order to carry out the present invention using a tandem rolling mill consisting of a plurality of rolling mills, the shift directions of the upper work rolls and the lower work rolls of adjacent rolling mills are It is desirable that the directions are opposite to each other. In addition, a mechanism that tilts the backup roll,
The mechanism for shifting the work roll does not require any limitation. It may be appropriately performed by a known means. For example, in order to shift the work roll, a mode in which the work roll neck portion is supported by a thrust bearing and a shift cylinder is engaged with the thrust bearing to shift the work roll can be exemplified. Further, the present invention will be described in detail with reference to examples, but this is merely an example of the present invention, and the present invention is not limited thereby.

[0024]

EXAMPLE FIG. 4 is a schematic explanatory view schematically showing a rolling mill for carrying out the work roll shifting method during rolling according to the present invention. The backup rolls 1 and 1 are held in the rolling mill housing 5 by the backup roll chocks 4 and 4. The backup roll chock 4 is in contact with the chock moving guides 6, 6 for crossing the backup roll 1 with respect to the work roll 2, and the jack 7 attached to the chock moving guide 6 is put in and taken out to move the backup roll chock 4. The cross angle θ is set to a predetermined angle. A similar mechanism is provided on the upper and lower backup rolls and on the operation side and the drive side, and the position control of each jack causes the work roll 2 to intersect at the barrel center of the backup roll 1 and the upper and lower rolls in opposite directions. The chock of the backup roll is moved so that it can be shifted to, that is, the cross direction of the upper and lower backup rolls is opposite.

Using the rolling machine shown in FIG. 4 having such a configuration, low carbon steel having a plate thickness of 1200 mm is continuously rolled for 9 minutes in continuous rolling, and the thickness is rolled from 7 mm to 5 mm at a speed of 400 m / min. Then, the effect of work roll shift during rolling was investigated. The results are shown in FIGS. 5 and 6.

5 (a) and 5 (b) are both schematic explanatory views showing the work roll profile after rolling.
5 (a) is an example in which the work rolls are not shifted during rolling, and Fig. 5 (b) is rolling at a cross angle θ2 °, and the shift force is intermittently applied to shift the work rolls at a speed of 20 mm / min. 1
An example is shown in which the shift time is 1 minute and the shift time is 1 minute. As shown in Fig. 5 (a), when the work roll is not shifted, a thermal crown of about 50 μm per radius is generated at the rolling material contact part other than near the strip width edge,
While the roll profile has a thermal crown that decreases rapidly near the edge of the strip width, as shown in Fig. 5 (b), when the work roll is shifted, the center of the sheet width direction makes contact. Although a thermal crown of about 50 μm is generated in the region where the heat treatment is performed as in FIG. 5 (a), a sharp roll profile disappears in the vicinity of the edge, resulting in a smooth roll profile.

FIGS. 6 (a) and 6 (b) are respectively shown in FIGS.
The plate profile corresponding to the case of rolling with the work roll shown in (b) is shown. When rolling with a roll profile as shown in FIG. 5 (a), when using a work roll bender so that a predetermined plate crown is obtained, as shown in FIG. 6 (a), the plate thickness becomes thicker near the edge. It became an abnormal profile.

On the other hand, in the case of the roll profile as shown in FIG. 5 (b), if the work roll bender force is set to an appropriate value, the plate crown can be made small as shown in FIG. It was possible to prevent the generation of profiles.

The work roll shift force according to the present invention under the above conditions was 100 ton, and there was no problem in shifting the work roll during rolling.

Further, rolling mills 8a, 8b and 8c having the same structure as the rolling mill shown in FIG. 4 described above are arranged in tandem as shown in FIG. 7 and the backup rolls 1a to 1c of the backup rolls 1a to 1c are arranged by the method according to the present invention. Work roll 2a with cross angle of 2 °
Shifted by 2c. In this example, as shown in FIG. 7, the work rolls were shifted so that the upper work rolls of the adjacent stands, the lower work rolls of the adjacent stands, and the upper and lower work rolls of the adjacent stands were in opposite directions. As a result, it was possible to perform stable rolling without causing meandering of the rolled material throughout rolling.

[0031]

As described in detail above, according to the present invention, the work roll during rolling can be easily shifted in the axial direction, and even if the work roll is shifted during rolling, meandering of the rolled material occurs. Instead, stable rolling became possible.
In particular, even when continuous rolling for a long time such as a finish continuous rolling method is performed, it is possible to disperse the thermal crown and roll wear, and it is possible to greatly contribute to the realization of finish continuous rolling of the hot rolled steel sheet. The significance of the present invention having such an effect is extremely remarkable.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing a work roll shift method during rolling according to the present invention.

FIG. 2 is a schematic explanatory view showing a conventional work roll shift method.

FIG. 3 is a graph showing the effect of reducing the work roll shift force by the work roll shift method during rolling according to the present invention.

FIG. 4 is a schematic explanatory view that schematically shows the configuration of the apparatus used in the examples of the present invention.

5 (a) and 5 (b) are schematic explanatory views showing the results of the examples of the present invention. FIG. 5 (a) shows a thermal roll of a work roll when the backup roll is not crossed, and FIG. 5 (b) shows a backup roll as a work roll. The thermal crowns of the work rolls when they intersect with each other by 2 ° are shown.

FIG. 6 is a schematic explanatory view showing results of an example of the present invention, FIG. 6 (a) shows a plate profile of a rolled material which is rolled by a work roll having the roll profile shown in FIG. 5 (a), Figure
6 (b) shows the plate profile of the rolled material rolled by the work roll having the roll profile shown in FIG. 5 (b).

FIG. 7 is a schematic explanatory view showing a rolling mill train according to an embodiment of the present invention.

[Explanation of symbols]

1,1a, 1b, 1c: Backup roll 2,2a, 2b, 2c: Work roll 3: Rolled material 4: Backup roll chock 5: Rolling mill housing 6: Chock moving guide 7: Jack 8a, 8b, 8c: Rolling mill

Claims (4)

[Claims] 1. A work roll shifting method at the time of rolling in which a work roll supported by a backup roll is shifted in the axial direction of the work roll at the time of rolling, wherein the backup roll located on the side for shifting the work roll. The work roll is shifted in a state where the axis of the backup roll is inclined in the horizontal plane with respect to the axis of the work roll so that the end is on the rolling mill exit side with respect to the other end. A work roll shift method during rolling, which is characterized by the above. 2. The work roll shifting method during rolling according to claim 1, wherein the axis of the backup roll and the axis of the work roll intersect at the center of the barrel of the backup roll. 3. The pair of upper and lower work rolls of the same rolling mill are shifted in opposite directions to each other.
Alternatively, the work roll shift method during rolling according to claim 2. 4. A tandem rolling mill comprising a plurality of rolling mills, wherein upper work rolls of adjacent rolling mills and lower work rolls of adjacent rolling mills are shifted in opposite directions to each other. The work roll shift method at the time of rolling according to any one of 1.