JP2001239309A - Rolling machine and method of rolling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling machine which can roll under high pressure without getting poor in being in gear with a pair of work rolls even when rolling a rolled material having a large plate thickness. SOLUTION: The rolling machine 1 is equipped with a pair of work rolls consisting of a first work roll 2 driving for rotation and a second work roll 3 being driven for rotation whose outer diameter is 70% or less of that of the first work roll 2, a backup roll 8 driving for rotation while supporting the second work roll 3 and a subsidiary driving mechanism 4 which subsidiarily drives the second work roll 3 with smaller torque than that of the first work roll 2 at least while since a tip portion of a hot rolling steel in coil 9 is geared into the second work roll 3, till the tip portion reaches a position which is a tip portion in the rolling direction of a roll bite of the second work roll 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a rolling mill and a rolling method. Specifically, the present invention relates to, for example, a rolling mill and a rolling method for performing high-pressure rolling with a high rolling reduction when performing finish rolling on a thin hot-rolled material having a plate thickness of 30 mm or less.

[0002]

2. Description of the Related Art For example, when hot finishing rolling is performed using a hot rolling mill for plate rolling comprising 5 to 7 stands of rolling mills, or a single machine such as a thick plate rolling mill or a Steckel rolling mill is used. When hot finishing rolling is performed by reversing rolling in multiple passes using a reversible rolling mill, the number of passes in hot finishing rolling is reduced, thereby reducing the cost of compact rolling equipment and finishing temperature for thin materials. There is a growing need for high-pressure rolling in which the rolling reduction of each pass is increased in order to secure the required rolling speed.

In order to perform high-pressure rolling in each pass of the hot finish rolling, the rolling load is reduced, and a stable rolling operation is performed by preventing a shape defect of the material to be rolled, which is called ear waves or medium elongation. It is important to do both. For this reason, it is known that high-pressure rolling can be performed by hot finish rolling by reducing the rolling load by using a work roll having a smaller diameter than a conventionally used work roll. However, simply reducing the diameter of each of the pair of work rolls makes it impossible to directly transmit the torque required for rolling to the work roll that is driven and rotated.

[0004] Therefore, there has been proposed a hot rolling mill in which only one of the pair of work rolls has an extremely small diameter and only the other work roll which does not have a small diameter is driven. For example, Journal of the Japan Society for Technology of Plasticity “Plasticity and Processing”, Vol. 31, No. 359 (December, 1990) 138
On pages 1-1389, a quadruple rolling mill having an upper work roll with a driven rotation of 300 mm in diameter and a lower work roll with a driven rotation of 600 mm in diameter is used as a sheet rolling heat source comprising a 6-stand rolling mill. It is disclosed that a hot-rolled steel strip having a thickness of 1 mm can be manufactured at a high rolling reduction of 65% by applying the present invention to the final stand of the finishing rolling equipment.

[0005]

However, according to a number of experiments conducted by the present inventor, one of the pair of work rolls has a very small diameter, and only the other work roll which does not have a small diameter. , It was found that, depending on the rolling conditions, rolling was frequently impossible due to a marked deterioration of the workability of the material to be rolled into the work roll pair.

[0006] That is, as disclosed in the above-mentioned document, a quadruple rolling mill provided with an upper work roll having a driven rotation of 300 mm in diameter and a lower work roll having a driven rotation of 600 mm in diameter is provided on a six-stand rolling mill. If applied to the final stand of the hot finishing rolling equipment for sheet rolling consisting of rolling mills, the sheet thickness is small and the bite angle is only about 6 degrees at most at most for the normal rolled material, Rolling can be performed without causing a rolling problem such as poor engagement of the material to be rolled into the work roll pair.

However, the rolling stand on the upstream side of the hot finishing rolling equipment for sheet rolling has a greater thickness of the material to be rolled,
The amount of reduction also increases. For this reason, when the above-mentioned quadruple rolling mill is applied to the rolling stand on the upstream side of the hot finishing rolling equipment for sheet rolling, the bite angle of the material to be rolled becomes extremely large, for example, about 10 degrees or more, for example, about 10 degrees. Therefore, a biting failure of the material to be rolled occurs. In the hot finishing rolling equipment for sheet rolling, if such a biting failure occurs, there is a high possibility that a serious trouble requiring a long time for recovery will occur.
Therefore, it is practically difficult to apply the above-mentioned quadruple rolling mill to a rolling stand on the upstream side of a hot finishing rolling mill for sheet rolling.

In the initial pass of finish rolling using a reversible rolling mill such as a thick rolling mill or a Steckel rolling mill, the material to be rolled is as thick as 30 mm or more. When using, poor biting tends to occur. In order to suppress the occurrence of this biting failure, it is necessary to increase the number of passes by reducing the rolling reduction of each pass. However, in this case, the number of passes is reduced by high-pressure rolling in the subsequent pass where the plate thickness is reduced. The effect is offset. Therefore, the above 4
It is practically difficult to apply a heavy rolling mill to a reversible rolling mill.

An object of the present invention is to provide a rolling mill and a rolling method capable of performing high-pressure rolling without causing a biting defect even when the material to be rolled has a large thickness. For example, when performing finish rolling on a thin hot-rolled material having a sheet thickness of 30 mm or less, a rolling mill and a rolling method capable of performing high-pressure rolling with a large reduction ratio are provided. Another object of the present invention is to increase the rolling limit of a rolling mill including a work roll, which is a driven roll having an extremely small diameter, and a work roll, which is a drive roll having a normal diameter.

[0010]

The inventor of the present invention has conducted various studies to solve the above-mentioned problems. As a result, in the case of a normal rolling mill which drives both upper and lower work rolls, the bite angle is, for example, 15 mm. Even when the rolled material is larger than the degree, the material to be rolled can be reliably engaged with each of the upper and lower work rolls and rolled, whereas when only one of the upper and lower work rolls is driven, the engagement angle is increased. Is too small to be rolled at a stage as small as about 6 degrees, that is, when only one of the upper and lower work rolls is driven, the bite of the material to be rolled is greatly deteriorated. I learned that

The present inventor has made further studies based on this finding, and as a result, one of the pair of work rolls has a very small diameter, and the other work roll, which has not been reduced, is set as the main drive. When the work roll having the extremely small diameter is reached, at least when the leading end of the material to be rolled reaches a position at which the work roll pair can pass from the time when the leading end of the work roll is bitten by the one work roll having the extremely small diameter. Until then, by driving auxiliary, the biting ability,
It can be greatly improved to the same level as existing rolling mills that drive both upper and lower work rolls,
The present inventors have found that even when the material to be rolled has a large thickness, it is possible to perform high-pressure rolling without causing biting failure of the material to be rolled, and have further studied to complete the present invention.

According to the present invention, there is provided a work roll pair comprising a first work roll which is driven and rotated, a second work roll which is smaller in diameter than the first work roll and is driven to rotate, and a second work roll. And a supplementary driving mechanism for supplementarily driving the rolling mill.

In the rolling mill according to the present invention, the auxiliary drive mechanism switches the second work roll at least when the leading end of the material to be rolled is bitten by the second work roll. It is desirable to drive until it reaches a passable position.

In the rolling mill according to the present invention, the position at which the work roll pair can pass is the position that is the leading end in the rolling direction of the roll bite of the second work roll.
Is exemplified.

In these rolling mills according to the present invention, it is desirable that the auxiliary drive mechanism drives the second work roll with a smaller torque than the first work roll.

In the rolling mill according to the present invention, the second
It is preferable that the outer diameter of the first work roll is 70% or less of the outer diameter of the first work roll.

Further, in the rolling mill according to the present invention, the auxiliary drive mechanism supports the second work roll and rotates the drive roll or the second work roll.
Having a rotary drive system connected to the work roll.

From another viewpoint, the present invention provides a work comprising a first work roll driven and rotated and a second work roll smaller in diameter than the first work roll and driven to rotate. This rolling method is characterized in that the second work roll is engaged with a pair of rolls while being driven auxiliary to reduce the roll.

In the rolling method according to the present invention, the second work roll is moved to a position where at least the leading end of the material to be rolled can pass through the pair of work rolls from the time when the leading end of the material is bitten by the second work roll. It is desirable to drive until it reaches.

In the rolling method according to the present invention, it is exemplified that the position that can pass through the work roll pair is the position that is the leading end of the roll bite of the second work roll in the rolling direction.

In the rolling method according to the present invention, it is desirable that the second work roll is driven with a smaller torque than the first work roll.

In the rolling method according to the present invention, the outer diameter of the second work roll is desirably 70% or less of the outer diameter of the first work roll.

Further, in the rolling method according to the present invention, the second work roll supports the second work roll and is driven and rotated by a backup roll, or a rotary drive connected to the second work roll. The auxiliary driving by the system is exemplified.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) Hereinafter, embodiments of a rolling mill and a rolling method according to the present invention will be described in detail with reference to the accompanying drawings. In the following description, the rolling mill according to the present invention is applied to a rolling stand on the upstream side of a hot rolling mill for plate rolling composed of a plurality of rolling stands, and the rolling mill according to the present invention includes a pair of backup mills. The case of a quadruple rolling mill provided with rolls is taken as an example.

FIG. 1 is an explanatory view schematically showing the configuration of a rolling mill 1 according to the present embodiment. In the following drawings, the rolls painted in black and white indicate rolls that are driven and rotated, and the rolls painted white are rolls that are driven and rotated.

As shown in FIG.
Is a first work roll 2 and a second work roll 3
And an auxiliary driving mechanism 4. Hereinafter, these components of the rolling mill 1 will be sequentially described.

[First work roll 2] The first work roll 2 has a normal outer diameter (for example, about 600 mm) as a work roll applied to a rolling stand on the upstream side of a hot finishing rolling mill for sheet rolling. It is a work roll having. A main drive motor 6 is connected to the first work roll 2 via a drive shaft 5. The drive shaft 5 may not be directly connected to the main drive motor 6 as shown, but may be connected to the main drive motor 6 via a speed reducer (not shown). Thereby, the drive torque of the first work roll 2 can be increased without increasing the motor power of the main drive motor 6.

The first work roll 2 is supported by a backup roll 7 that rotates following the first work roll 2.

As described above, the first work roll 2 is driven and rotated by the main drive motor 6. For this reason, the torque required for rolling, that is, rolling energy, is supplied to the first work roll 2 by the main drive motor 6.

The other structure of the first work roll 2 may be the same as the structure of a well-known and ordinary work roll.
Further description of the first work roll 2 will be omitted.

In the present embodiment, the first work roll 2 is configured as described above.

[Second work roll 3] The second work roll 3 is an extremely small diameter work roll having a smaller diameter than the first work roll 2.

FIG. 2 is a graph showing an example of the relationship between (diameter of second work roll 3 / diameter of first work roll 2) and the rolling load ratio. The outer diameter of the second work roll 3 is preferably smaller in order to obtain a large effect of reducing the rolling load, but the rolling load ratio in the conventional rolling using a rolling mill having the same outer diameter of each of the pair of work rolls ( =
If the rolling load can be reduced by 10% or more with respect to 1.0), shape control characteristics can be improved and high-pressure rolling can be performed. Therefore, from the graph shown in FIG. 2, it is desirable to set the roll diameter to 70% or less in diameter ratio with the first work roll 2. The diameter ratio with the first work roll 2 is 50
% Is more desirable, and in this case, the effect of reducing the rolling load is 25% or more, and high-pressure rolling can be performed at the same load and the same shape control ability with the rolling reduction increased by about 10%.

Neither the main drive motor nor the drive shaft is connected to the second work roll 3, and the second work roll 3 is driven to rotate.

The second work roll 3 is supported by a backup roll 8 having substantially the same diameter as the backup roll 7.

The second work roll 3, together with the first work roll 2, performs finish rolling of a hot-rolled steel strip 9 as a material to be rolled.

The other structure of the second work roll 3 is described in, for example, the aforementioned Journal of the Japan Society for Technology of Plasticity, “Plasticity and Working”, Vol. 31, No. 359 (December 1990), 1381.
Since the upper work roll disclosed on pages 1 to 1389 may be the same, further description of the second work roll 3 will be omitted. In the present embodiment, the second work roll 3 is configured as described above.

[Auxiliary drive mechanism 4] Rolling mill 1 of the present embodiment
Has an auxiliary drive mechanism 4. This auxiliary driving mechanism 4
In the present embodiment, the backup roller 8 includes a backup roll 8, a drive shaft 10 connected to the backup roll 8, and an auxiliary drive motor 11 connected to the drive shaft 10.

The backup roll 8 is driven to rotate by an auxiliary drive motor 11. Thereby, the second work roll 3 supported by the backup roll 8 is also driven auxiliary.

The auxiliary drive motor 11 for driving the backup roll 8 drives the backup roll 8 and the second work roll 3 at least from before the rolling until the tip of the hot-rolled steel strip 9 is rolled. It is not necessary to supply the rolling energy over the entire region from the start of rolling to the completion of rolling. Accordingly, the power required for the auxiliary drive motor 11 may be very small, and may be about 5% or more of the motor power of the main drive motor 6 required for rolling. In order to secure a stable biting property even when the rolling conditions such as the steel type and the temperature drop of the hot-rolled steel strip 9 fluctuate,
Although it is advantageous that the motor power of the auxiliary drive motor 11 is large, it is sufficient if the auxiliary drive motor 11 has a capacity of about 20% of the main drive motor 6. As a result, the second work roll 3 is driven auxiliary by the auxiliary drive mechanism 4 with a torque smaller than that of the first work roll 2.

The auxiliary drive of the second work roll 3 by the auxiliary drive mechanism 4 is performed at least at a position where the leading end of the hot-rolled steel strip 9 can pass through the work roll pair from the time when the tip end of the hot rolled steel strip 9 bites the second work roll 3. If such a process is carried out until the time when the steel strip 9 is reached, the biting failure of the hot-rolled steel strip 9 does not occur. Also, the time during which the tip of the hot-rolled steel strip 9 bites into the first work roll 2 and the second work roll 3, that is, the time when it passes through the roll bite, is usually about 10 ^-2 to 10 ^-1 seconds. Extremely short. Therefore, in the present embodiment, the position that can pass through the work roll pair is set to a position that is the leading end in the rolling direction (right direction in FIG. 1) of the roll bite of the second work roll 3 in consideration of safety.

Before the leading end of the hot-rolled steel strip 9 reaches the leading end of the second work roll 3 in the rolling direction of the roll bite, the auxiliary driving mechanism 4 stops the auxiliary driving of the second work roll 3. However, at this time, if the tip of the hot-rolled steel strip 9 has reached a position where it can pass through the work roll pair,
Due to the inertia of the second work roll 3 during rolling, the hot rolled steel strip 9 can pass through the work roll pair. Therefore, in the present invention, the auxiliary drive of the second work roll 3
It may be performed at least from the time when the tip end portion of the hot-rolled steel strip 9 is bitten by the second work roll 3 to the time when it reaches a position where it can pass through the work roll pair. The “position at which the end of the hot-rolled steel strip 9 can pass through the work roll pair” is determined according to the rolling conditions.

In the present embodiment, the control device (not shown) starts to move the tip end of the hot-rolled steel strip 9 between the second work roll 3 and the second work roll 3 in the rolling direction of the roll bite. Until it reaches the position of the tip,
The second work roll 3 is auxiliary-driven by the auxiliary drive mechanism 4.

In the present embodiment, the auxiliary drive mechanism 4 is configured as described above.

Next, the first work roll 2, the second work roll 3, and the backup rolls 7 and 8
The situation in which the hot rolling steel strip 9 is rolled by the double rolling mill 1 will be described.

In this embodiment, the tip of the hot-rolled steel strip 9 conveyed rightward in FIG. 1 is bitten by the second work roll 3 while driving and rotating the first work roll 2. From time to the time when the second work roll 3 reaches a position which is the leading end in the rolling direction of the roll bite, the second work roll 3 is driven with a torque smaller than that of the first work roll 2. Then, the hot-rolled steel strip 9 is bitten and reduced.

In the present embodiment, the auxiliary drive mechanism 4 operates from the time when the hot-rolled steel strip 9 is bitten by the second work roll 3 to the time when the hot-rolled steel strip 9 reaches the position of the leading end in the rolling direction of the roll bite. Since the second work roll 3 is auxiliary driven, the upper and lower work rolls have substantially the same sufficient biting properties as an existing rolling mill in which both upper and lower work rolls are drive rolls having the same diameter. Among the hot-rolling finishing equipment for plate rolling consisting of a stand, poor biting does not occur even in the upstream rolling stand where the bite angle is likely to be 10 degrees or more due to the large thickness of the hot-rolled steel strip 9. .

In this rolling, the peripheral speed of each of the first work roll 2 and the second work roll 3 is such that the warp of the hot-rolled steel strip at the exit side of the rolling mill is different from that of the above-mentioned existing rolling mill. It is not necessary to control with high accuracy of 0.1% in order to prevent occurrence. The peripheral speed of the first work roll 2 transmitting the rolling torque determines the traveling speed of the hot-rolled steel strip 9, and the peripheral speed of the second work roll 3 corresponds to the peripheral speed of the first work roll 2. May be determined as appropriate. For this reason, the peripheral speed of the second work roll 3 may be appropriately set so as to be substantially equal to the peripheral speed of the first work roll 2.

When the end of the hot-rolled steel strip 9 that has passed through the first work roll 2 and the second work roll 3 is warped, the installation position of the second work roll 3 is appropriately adjusted in the rolling direction. It is desirable to install the hot-rolled steel strip 9 at an offset by an appropriate distance, whereby the warpage of the end of the hot-rolled steel strip 9 is eliminated.

As described above, in the present embodiment, briefly, the roll diameter of the second work roll 3 is set to 70% or less of the roll diameter of the first work roll 2 having a normal roll diameter. The second work roll 3 is driven auxiliary until the tip of the hot-rolled steel strip 9 as the material to be rolled is rolled. Thereby, according to the present embodiment, even when the thickness of the hot-rolled steel strip 9 is large, high-pressure rolling can be performed without causing poor biting. Specifically, for example, when performing finish rolling on a thin hot-rolled material 9 having a thickness of 30 mm or less, a rolling mill 1 and a rolling method capable of performing high-pressure rolling with a large reduction ratio are provided. be able to.
For this reason, the rolling mill 1 including the second work roll 3 having an extremely small diameter and the first work roll 2 having a normal diameter.
Rolling limit can be expanded.

Furthermore, according to the present embodiment, the effect of the second work roll 3 having a very small diameter enables the rolling with a low load even in the high-pressure rolling, whereby the hot-rolled steel strip 9 after the finish rolling is formed.
Can be made smaller, and the thickness accuracy can be improved.

(Second Embodiment) Next, a second embodiment will be described. In the following description of each embodiment, portions different from the above-described first embodiment will be described, and common portions will be denoted by the same reference numerals in the drawings, and redundant description will be omitted.

FIG. 3 is an explanatory view schematically showing the configuration of the rolling mill 1-1 of the present embodiment. In the first embodiment, the backup roll 8 is driven by the auxiliary drive mechanism 4, thereby auxiliary driving the second work roll 3. In the present embodiment, however, the second work roll 3 and the backup roll 8 are connected to each other. In between, a backup roll 8-1 having a small diameter is provided to form a five-fold rolling mill 1-1, and the backup roll 8-1 is driven by the auxiliary drive mechanism 4 to auxiliary-drive the second work roll 3. Things.

According to the present embodiment, by making the diameter of the backup roll 8-1 substantially the same as that of the work roll 2, the roll rotation speeds of the backup roll 8-1 and the work roll 2 can be made substantially the same. Accordingly, the peripheral speeds of the small-diameter work roll 3 and the work roll 2 can be made substantially the same, and the merit that warpage can be reliably prevented can be obtained.

(Third Embodiment) FIG. 4 is an explanatory view schematically showing a configuration of a rolling mill 1-2 of the present embodiment. In this embodiment, the second work roll 3 is provided with an auxiliary drive mechanism 4 as a rotation drive system, and the auxiliary work mechanism 4 directly auxiliary-drives the second work roll 3.

According to the present embodiment, since the small-diameter work roll 3 is rotated, there is an advantage that the rotary drive system equipment becomes more compact. Note that the maximum transmittable torque decreases in proportion to the third power of the roll diameter, so that the second work roll 3 is smaller than the first embodiment.
The limit of diameter reduction becomes lower.

(Fourth Embodiment) FIGS. 5A and 5B are explanatory views showing the structure of a backup roll 8-1 used in this embodiment. FIG. 5A is a longitudinal sectional view, and FIG. It is an AA sectional view in (a).

In this embodiment, as in the first to third embodiments, an auxiliary drive mechanism 4 including a drive shaft 10 and an auxiliary drive motor 11 is provided to drive a backup roll 8 or a second work roll 3. Instead, the auxiliary drive mechanism 4-1 is built in the backup roll 8-1 to auxiliary-drive the second work roll 3.

That is, as shown in FIGS. 5 (a) and 5 (b), the backup roll 8-1 comprises a rotary sleeve 12 and a fixed arbor 13,
The backup roll 8-1 itself is driven by an auxiliary drive mechanism 4-1 including an auxiliary drive motor 14 incorporated in the arbor 13 and a drive wheel 15 for transmitting the rotation of the auxiliary drive motor 14 to the sleeve 12. It is a drive roll.

That is, the auxiliary driving mechanism 4 in the present invention
Since -1 only needs to be able to generate a small torque, a versatile and compact auxiliary drive mechanism as exemplified in the present embodiment can be used.

[0061]

EXAMPLES The present invention will be described more specifically with reference to examples.

(Example 1) A rolling mill 1 according to the present invention shown in FIG. 1, a conventional rolling mill 16 schematically shown in FIG. 6, and a comparison schematically shown in FIG. Each of the rolling mills 22 of the example was incorporated into an upstream rolling stand in a hot finishing rolling mill for sheet rolling, and the sheet thickness was 2 to 10 mm.
hot rolled steel strip 9 (rolling temperature: 1000 ° C.) made of low carbon steel having a thickness of 100 to 300 mm and a width of 100 m / m
Finish rolling was performed at a rolling speed of 1 minute, and the biting property was investigated.

The conventional rolling mill 16 shown in FIG.
The upper and lower work rolls 17 and 18 have the same diameter and are both connected to a main drive motor 21 via a drive shaft 19 and a cam waltz 20. The rolling mill 22 of the comparative example shown in FIG. 7 is the same as the above-mentioned Journal of the Japan Society for Technology of Plasticity “Plasticity and Working”, Vol. 31, No. 359 (December 1990) 1381.
To 1389, except that the auxiliary drive mechanism 4 is not connected to the second work roll 3 in the same manner as the rolling mill 1 according to the present invention shown in FIG. It is configured.

The diameter of the work rolls in each of the rolling mill 1, the rolling mill 16 and the rolling mill 22 is 100 mm for the second work roll 3, and 200 mm for the other work rolls 2, 17 and 18, respectively. did.

FIG. 8 is a graph showing the results. In addition, as shown in the graph of FIG.
The evaluation was made based on the maximum bite angle θ (deg) of the hot-rolled steel strip (rolled material) at a rolling reduction (mm) of 0 to 15 mm. In addition, in the graph of FIG. 8, a circle indicates that the rolling mill 1 was able to bite, and a black circle indicates that the rolling mill 1 was not bitable. In addition, □ indicates that the rolling mill 16 could bite, and Δ indicates that the rolling mill 16 could not bite. In addition, △
The mark indicates that the rolling mill 22 could bite, and the symbol ▲ indicates that the rolling mill 22 could not bite.

As is apparent from the graph of FIG. 8, in the rolling mill 22 of the comparative example, when the bite angle exceeds about 6 degrees, the hot-rolled steel strip 9 does not bite into the second work roll 3 and cannot be rolled. Becomes For this reason, the rolling mill 22 of the comparative example can be applied only to the finishing mill final stand or a stand one stand upstream from the final stand in consideration of the manufacturing dimensional configuration and the rolling operation stability.

On the other hand, in the rolling mill 1 of the embodiment of the present invention, the second driving mechanism 4
Since the work roll 3 is auxiliary-driven, a biting failure does not occur until the biting angle becomes about 17 degrees, and a biting property substantially equal to that of the conventional rolling mill 16 is obtained. As described above, since the rolling mill 1 of the example of the present invention can secure substantially the same biting property as that of the rolling mill 16 of the conventional example, the rolling mill 1 of the sheet finishing hot finishing rolling equipment having ordinary 5 to 7 stands can be used. The present invention can be sufficiently applied to not only the downstream rolling stand but also the upstream rolling stand.

(Embodiment 2) A rolling mill 1 according to the present invention shown in FIG. 1 and a conventional rolling mill 16 whose structure is schematically shown in FIG. Of the hot-rolled steel strip 9 was subjected to finish rolling, and the biting property was investigated. Table 1 shows test conditions
Are shown together.

[0069]

[Table 1]

In the rolling mill 1, the second work roll 3
In the case where is not auxiliary-driven, the limit of engagement was 15% when the opening degree was initially set to 1.4 mm (tip engagement angle was 6.1 degrees) and the thickness after rolling was 1.85 mm. On the other hand, when the second work roll 3 is auxiliary-driven, even if the opening degree is set to 0 mm (the upper and lower work rolls are kissed), biting and rolling are possible, and the sheet thickness after rolling is reduced to 1.17 mm. And high-pressure rolling with a reduction of 45%. At this time, the bite angle θ of the leading end of the material 9 to be rolled was 10.3 (deg).

FIGS. 9 and 10 are graphs showing the effects of the high-pressure rolling of the rolling mill 1 according to the present invention and the rolling mill 16 of the conventional example, respectively. FIG.
(%) And the rolling load P (ton) are shown in FIG.
Indicates the relationship between the sheet thickness h (mm) after rolling and the sheet crown C ₅ (μm). 9 and 10 indicate the results of the rolling mill 1 according to the present invention, and ● indicates the results of the rolling mill 16 of the conventional example.

As shown in the graph of FIG. 9, the rolling load P (ton) by the rolling mill 1 is 2
5 to 35%, and the same rolling load, e.g.
At 00 tons, the rolling reduction was 30% in the rolling mill 16, whereas the rolling reduction was 45% in the rolling mill 1.

As shown by the graph in FIG. 10, the rolling mill 1 according to the present invention, which can reduce the rolling load by reducing the diameter of the work roll, can reduce the edge drop by the small-diameter work roll. In the same rolling conditions, the sheet crown can be greatly reduced. Therefore,
Since the sheet crown is small, the occurrence of the rim wave shape defect can be reduced, and the high-pressure rolling becomes easy.

That is, as is apparent from the graph shown in FIG. 10, if the steepness of 2.5% is considered as the rolling limit due to the shape defect, the rolling mill 16 of the conventional example has a thickness h after rolling.
= 1.65 mm (rolling reduction about 20%) is the rolling limit, but the rolling mill 1 according to the present invention has a thickness h = 1.2 after rolling.
Rolling to 5 mm (reduction rate of about 40%) is possible, and a high-pressure reduction effect of doubling the reduction rate is obtained.

(Embodiment 3) A rolling mill 1 according to the present invention shown in FIG. 1 (diameter of first work roll 2: 400 mm, second work roll 2
Diameter of work roll 3: 750 mm, work roll diameter ratio: 0.53, diameter of backup rolls 7 and 8: 145
0 mm) is applied to each of the five upstream stands of the seven-stand hot rolling mill for plate rolling, and a sheet width 1 of 0.05% carbon steel under the conditions shown in Table 2.
A finish rolling simulation of a 300 mm hot-rolled steel strip 9 was performed. The hot-rolled steel strip 9 is the rolled material having the smallest finished plate thickness among the rolled materials rolled by the hot rolling mill for plate rolling.

[0076]

[Table 2]

The results are shown in Table 3 together with the case of the rolling mill 22 of the comparative example described with reference to FIG.

[0078]

[Table 3]

As is clear from Table 3, if the rolling mill 1 according to the present invention is applied to each of the five upstream stands,
While reducing the load by reducing the diameter of the work roll and preventing shape defects, it is possible to perform stable rolling of thin materials without operation troubles such as narrowing down at all the rolling stands F1 to F7.

(Modification) In the description of each of the embodiments and examples, the rolling mill according to the present invention is applied to a rolling stand on the upstream side of a hot rolling mill for plate rolling comprising a plurality of rolling stands. Was taken as an example. However, the present invention is not limited to the rolling stand on the upstream side of the hot rolling mill for plate rolling, and the rolling stands on the downstream side other than the upstream side of the hot finishing rolling mill for plate rolling, and the rolling for thick plates. The present invention can be similarly applied to a reversible rolling mill such as a mill or a Steckel rolling mill.

In the description of each embodiment and each example, the case where the rolling mill according to the present invention is a quadruple rolling mill or a quintuple rolling mill provided with a pair of backup rolls is taken as an example. However, the present invention relates to a quadruple rolling mill or 5
The present invention is not limited to heavy rolling mills, and is similarly applied to other multiple rolling mills.

Further, in the description of each embodiment and each example, the case where the material to be rolled is a hot-rolled steel strip is taken as an example. However, the present invention is not limited to a hot-rolled steel strip, and is equally applicable to a rolled material other than a hot-rolled steel strip, such as a material for a thick plate.

[0083]

As described above in detail, according to the present invention, there is provided a rolling mill and a rolling method capable of performing high-pressure rolling without causing poor biting even when the material to be rolled has a large thickness. To provide, specifically, for example, when performing finish rolling on a thin hot-rolled material having a thickness of 30 mm or less, a rolling mill and a rolling method capable of performing high-pressure rolling with a large rolling reduction. Could be provided. This makes it possible to increase the rolling limit of a rolling mill including a work roll, which is a driven roll having an extremely small diameter, and a work roll, which is a drive roll having a normal diameter.

Therefore, the effects listed below, that is, (i) the number of rolling stands of the hot rolling equipment for sheet rolling can be reduced, and (ii) the hot rolled steel strip having a small sheet thickness can be stably rolled without a defective shape. (Iii) Since high-pressure rolling can be performed, the temperature drop in the finishing mill is reduced, and high-temperature finishing can be performed even with a thin material to improve the product characteristics. (Iv) The temperature drop of the material to be rolled is reduced. Since the number is reduced, various advantageous effects such as lowering of the heating temperature and (v) easy rolling of a hard and difficult-to-roll material such as a high-tensile steel plate can be achieved. The significance of the present invention having such an effect is extremely remarkable.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram schematically showing a configuration of a rolling mill according to a first embodiment.

FIG. 2 is a graph showing an example of a relationship between (diameter of second work roll / diameter of first work roll) and a rolling load ratio.

FIG. 3 is an explanatory diagram schematically showing a configuration of a rolling mill according to a second embodiment.

FIG. 4 is an explanatory view schematically showing a configuration of a rolling mill according to a third embodiment.

FIG. 5 is an explanatory view showing a structure of a backup roll used in a fourth embodiment, FIG. 5 (a) is a longitudinal sectional view, and FIG.
FIG. 5B is a cross-sectional view taken along the line AA in FIG.

FIG. 6 is an explanatory view schematically showing a configuration of a conventional rolling mill in Embodiment 1.

FIG. 7 is an explanatory view schematically showing a configuration of a rolling mill of a comparative example in Example 1.

FIG. 8 is a graph showing the results of Example 1.

FIG. 9 is a graph showing the relationship between the rolling reduction r (%) and the rolling load P (ton) of the rolling mill according to the present invention and the rolling mill of the conventional example in Example 2.

FIG. 10 is a graph showing the relationship between the strip thickness h (mm) and the strip crown C ₅ (μm) of each of the rolling mill according to the present invention and the conventional rolling mill in Example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rolling machine 2 1st work roll 3 2nd work roll 4 Auxiliary drive mechanism 8 Backup roll 9 Hot rolled steel strip

Claims (6)

[Claims] 1. A work roll pair including a first work roll that is driven and rotated, a second work roll that is smaller in diameter than the first work roll and that is driven to rotate, and assists the second work roll. A rolling mill, comprising: an auxiliary drive mechanism for driving the rolling mill. 2. The auxiliary drive mechanism according to claim 1, wherein the second work roll is provided at least at a tip end of a material to be rolled.
2. The rolling mill according to claim 1, wherein the rolling mill is driven from a time when the work roll is caught by the work roll to a time when the work roll reaches a position where the work roll pair can pass. 3. The outer diameter of the second work roll is 70% or less of the outer diameter of the first work roll.
Or the rolling mill according to claim 2. 4. A work roll pair comprising a first work roll that is driven and rotated and a second work roll that is smaller in diameter than the first work roll and that is driven and rotated by the second work roll. And rolling the work roll while assisting the work roll. 5. The method according to claim 5, wherein the second work roll is moved at least when the leading end of the material to be rolled reaches a position where the work roll pair can pass from the time when the leading end portion is bitten by the second work roll. The rolling method according to claim 4, wherein the rolling method is performed until the rolling is completed. 6. The outer diameter of the second work roll is 70% or less of the outer diameter of the first work roll.
Or the rolling method according to claim 5.