JP6809275B2 - Rolling machine - Google Patents

Description

The present invention relates to rolling mills (particularly 4-step and 6-step rolling mills), and relates to rolling mills such as backup rolls and intermediate rolls that can reduce the load on rolls that receive rolling loads due to contact between rolls.

For example, when rolling a rolled material that requires a high rolling load with a four-stage hot rolling mill at a high reduction rate, the load becomes large, so the contact surface pressure (hertz pressure) between the work roll and the backup roll increases. It can be excessive. This causes a problem that fatigue fracture of the backup roll occurs.

To solve such a problem, there is a measure to reduce the rolling load generated in rolling by reducing the diameter of the work roll. However, there is a limit to reducing the diameter of the work roll from the viewpoint of ensuring the transmission of the driving torque. There is also a limit to the load capacity of the rolling mill.

On the other hand, for example, Patent Document 1 discloses a technique for reducing a rolling load by using a lubricant.

Further, Patent Document 2 and Patent Document 3 disclose a technique for arranging a support roll.

Japanese Patent No. 5573583 Japanese Unexamined Patent Publication No. 5-317917 Japanese Unexamined Patent Publication No. 2014-223646

However, as described in Patent Document 1, when a lubricant is used, the tip of the rolled material cannot penetrate between the work rolls and slips occur (poor biting property), and there is a troublesome problem in handling the lubricant. To do.

Further, the support rolls such as Patent Document 2 and Patent Document 3 have not been examined and configured to reduce the contact pressure between the work roll and the backup roll, and the problem cannot be solved.

There is also a method of supporting work rolls with multiple rolls in a multi-stage rolling mill other than a four-stage rolling mill (a rolling mill having two work rolls and two backup rolls) (for example, a cluster rolling mill having two backup rolls on one side). Although it has been proposed, the size of the rolling mill is large for use in a tandem rolling mill such as hot-rolled finish rolling, and the structure for roll replacement is too complicated to use.

Therefore, in view of the above problems, the present invention can reduce the occurrence of defects due to the contact load of rolls that receive rolling load due to contact between rolls, such as backup rolls and intermediate rolls, particularly for 4-stage and 6-stage rolling mills. The subject is to provide a rolling mill.

As a result of diligent studies, the inventors often have a problem with the upper limit of the contact surface pressure between the work roll and the backup roll when designing a four-stage rolling mill, and the contact surface pressure is set to, for example, about 10%. If it can be lowered, the situation will be balanced with the limit of the load capacity of the rolling mill, and we have obtained the knowledge that efficient rolling mill design is possible. Similar findings were obtained regarding the contact surface pressure between the intermediate roll and the backup roll of the 6-stage rolling mill. Further, since the work roll and the intermediate roll are manufactured with higher strength than the backup roll, when the same contact surface pressure is applied, a problem occurs on the backup roll side having a lower strength. From the above, it is assumed that the above problems can be solved by reducing the load due to the contact between the work roll and the backup roll in the 4-stage rolling mill and the load due to the contact between the intermediate roll and the backup roll in the 6-stage rolling mill. The invention was completed. Hereinafter, the present invention will be described with reference to a four-stage rolling mill for easy understanding.

One desirable aspect of the present invention is that in the case of a four-stage rolling mill, the work roll and the outer peripheral surface of the work roll are brought into contact with each other so that the roll center position is substantially vertical to the center position of the work roll. It is provided with a backup roll arranged so as to be, and a pressing head arranged on each of the upstream side and the downstream side of the work roll and in contact with the work roll and the backup roll, and the pressing head is in contact with the backup roll. It has a pressing portion and a second pressing portion that comes into contact with the work roll, and the first pressing portion and the second pressing portion have a wedge shape so that the distance approaches the tip, and the tip has a wedge shape. A rolling mill arranged toward the side where the work roll and the backup roll come into contact with each other.
On the other hand, in the case of a 6-stage rolling mill, the work roll described in the 4-stage rolling mill may be replaced with an intermediate roll.

In this rolling mill, at least one of the first pressing portion and the second pressing portion may be configured to have an injection port into which cooling water is injected.

Further, at least one of the first pressing portion and the second pressing portion is provided with a contact roller, and the contact roller is configured to come into contact with at least one of a work roll, an intermediate roll, and a backup roll. You can also do it.

According to the present invention, the contact surface pressure between the rolls such as the contact surface pressure between the work roll and the backup roll or the contact surface pressure between the intermediate roll and the backup roll can be reduced by the pressing pressure of the pressing head. It is possible to suppress problems such as damage to the product.

It is a figure which showed the part of the manufacturing equipment 1 of a hot-rolled steel sheet schematically. It is a figure explaining the rolling mill 27 provided with the pressing device 30. It is a figure explaining the pressing device 30. FIG. 4A is a diagram for explaining the first pressing portion 31a, and FIG. 4B is a diagram for explaining the second pressing portion 31b. FIG. 5A is a diagram for explaining the first pressing portion 31a of another example, and FIG. 5B is a diagram for explaining a second pressing portion 31b of another example. It is a figure explaining the 1st pressing part 31a of another example. It is a figure explaining the force generated by the contact when the pressing device 30 is not arranged. It is a figure explaining the effect when the pressing device 30 is arranged. FIG. 9A is a diagram for explaining the pressing member 130, and FIG. 9B is a diagram for explaining the first pressing portion 131a. It is a figure explaining the example of the 6-stage rolling mill 227. It is a graph which shows the result of an Example.

The present invention will be described based on the embodiments shown in the drawings. However, the present invention is not limited to these forms.

FIG. 1 shows the hot finish rolling mill row 10 and the output side cooling device 40 of the hot-rolled steel sheet manufacturing facility 1 (hereinafter, may be referred to as “manufacturing facility 1”) according to the first embodiment. It is a conceptual diagram showing the part of. In FIG. 1, the steel plate S is conveyed from the left side (upstream side, upper process side) to the right side (downstream side, lower process side) of the paper surface, and the top and bottom of the paper surface are in the vertical direction. Here, the pass line is shown by a broken line. The direction from the upstream side (upper process side) to the downstream side (lower process side) may be described as the plate width direction, and the plate width direction of the steel plate S to be passed is the plate width direction in the direction orthogonal to this. May be described. Further, in the figure, the description of the repeated reference numerals may be omitted for the sake of readability.

As shown in FIG. 1, the manufacturing facility 1 includes a hot finish rolling mill row 10 and a discharge side cooling device 40. Although illustration and description are omitted, a deskler, a heating furnace, a rough rolling mill row, and the like are arranged on the upstream side of the hot finish rolling mill row 10. On the other hand, a winder or the like is arranged on the downstream side of the cooling device 40. Further, in order to convey the steel sheet, a transfer roll (for example, the transfer roll 2 in FIG. 1) is provided as needed.

The hot finish rolling mill row 10 of this embodiment has first stands 11 to seventh stands 17 from the upstream side, and these are arranged along the plate passing direction. In this embodiment, each stand is provided with rolling mills 21 to 27, and the rolling mill 27 of the final stand 17 is provided with a pressing device 30. In the present embodiment, in the rolling mills 21 to 26 of the first stand 11 to the sixth stand 16, backup rolls 21a to 26a are provided in a housing (not shown), and work rolls 21b to 26b are provided between the two backup rolls 21a to 26a. Is placed. Then, rolling is performed by passing the steel plate S, which is a rolled material, between the two work rolls 21b to 26b.
Such a rolling stand is known, and each component provided in the rolling stand is also known.

As described above, in the present embodiment, the rolling mill 27 is provided in the seventh stand 17, which is the final stand. FIG. 2 shows the configuration of the rolling mill 27 in FIG. 1 in a schematic diagram. As can be seen from FIG. 2, the rolling mill 27 includes a backup roll 27a, a work roll 27b, a housing 27c, and a pressing device 30 as a first roll. Here, as the housing 27c, the backup roll 27a, and the work roll 27b, the same ones as those of the rolling mills of other rolling stands can be used.
Here, an example in which the pressing device 30 is arranged on the rolling mill 27 of the final stand will be described, but the rolling mill provided with the pressing device 30 is not particularly limited, and is a rolling mill of another stand. May be good.

The backup roll 27a and the work roll 27b are usually located at positions where the roll centers of both rolls are substantially perpendicular (vertical) to the rolling direction, that is, the horizontal direction, in order to efficiently receive the rolling reaction force in the housing 27c of the rolling mill. Is located in. However, this center position is often set with an offset amount of several mm in the rolling direction, thereby stabilizing the horizontal position of the work roll. In this embodiment, the above offset amount is not particularly limited, but the case where a value of 0 mm to about 2% or less with respect to the work roll diameter is set as the offset amount is also targeted.

In the present embodiment, the pressing device 30 contacts both the work roll and the first roll arranged so as to contact the outer peripheral surface of the work roll, and generates a force in the direction of separating the two. It is a device. As a result, the contact surface pressure generated between the two can be reduced. In this embodiment, the pressing device 30 is applied to the work roll 27b and the backup roll 27a as the first roll. Therefore, in the present embodiment, the pressing device 30 is arranged between the work roll 27b and the backup roll 27a at each of the four locations in total, the upper and lower two locations on the upstream side and the upper and lower two locations on the downstream side.
FIG. 3 shows an enlarged view focusing on one of the pressing devices 30 in FIG. 2. Further, FIG. 4A shows the first pressing portion 31a viewed from the side facing the backup roll 27a, and FIG. 4B shows the second pressing portion 31b viewed from the side facing the work roll 27b. The figures are shown respectively.

The pressing device 30 of this embodiment includes a pressing head 31 and a driving device 35.

As can be seen from FIG. 3, the pressing head 31 has a first pressing portion 31a facing the backup roll 27a and a second pressing portion 31b facing the work roll 27b. Therefore, the first pressing portion 31a has the same curvature as the outer circumference of the backup roll 27a, and the second pressing portion 31b has a curvature having the same curvature as the outer circumference of the work roll 27b.
The first pressing portion 31a and the second pressing portion 31b are arranged so as to approach each other toward the tip end (opposite side of the driving device 35). This is the same as the form in which the outer peripheral surfaces approach each other as the contact point between the backup roll 27a and the work roll 27b approaches. As a result, the pressing head 31 has a wedge shape that tapers as it approaches the tip.

The first pressing portion 31a and the second pressing portion 31b are curved as described above from the viewpoint of FIG. 3, have a wedge shape, and are shown in FIGS. 4 (a) and 4 (b) in the plate width direction. As shown in the above, the backup roll 27a and the work roll 27b are rectangular so that they can face each other over the entire length in the width direction.

In this embodiment, as can be seen from FIGS. 3, 4 (a) and 4 (b), the first pressing portion 31a is provided with a contact roller 32, and the second pressing portion 31b is provided with a contact roller 33. .. The contact rollers 32 and 33 are arranged on one end side and the other end side in the bending direction of the first pressing portion 31a and the second pressing portion 31b to form two rows, and the rotation axes of both rows are parallel to the plate width direction. .. In this embodiment, a plurality of contact rollers 32, 33 are arranged on the same rotation axis in the plate width direction in each row.
In this embodiment, the contact rollers 32 and 33 are arranged as described above, but the present invention is not limited to this, and for example, as shown in FIGS. 5 (a) and 5 (b), FIG. 5 (a) The contact rollers 32 and 33 are arranged so as to alternate between the surface of the first pressing portion 31a and the surface of the second pressing portion 31b of FIG. 5B so that the positions of the opposing rolls do not overlap. You may. This makes it possible to increase the diameter of the contact roller and improve the durability of the device.

As can be seen from FIG. 3, the contact rollers 32 and 33 are arranged so that a part thereof protrudes, the contact roller 32 of the first pressing portion 31a comes into contact with the surface of the backup roll 27a, and the contact roller of the second pressing portion 31b. 33 is configured to come into contact with the surface of the work roll 27b and rotate.

Further, the first pressing portion 31a and the second pressing portion 31b are provided with cooling water injection ports 31c between the contact rollers 32 and 33 arranged in two rows, and cooling water is provided from equipment (not shown). The water is injected from the injection port 31c. As a result, the backup roll 27a and the work roll 27b can be cooled at the same time. The cross-sectional shape and arrangement of the injection port 31c are not particularly limited and may be appropriately changed.

Further, in the above embodiment, the contact rollers 32 and 33 are arranged on one end side and the other end side in the bending direction of the first pressing portion 31a and the second pressing portion 31b to form two rows, and the rotation shafts of both rows are plates. It is parallel to the width direction and has an injection port 31c between the two rows of contact rollers 32 and 33. However, the present invention is not limited to this, and as shown in FIG. 6, for example, four rows of contact rollers 32 are arranged between one end side and the other end side in the bending direction, and the contact rollers 32 are arranged between adjacent rows. They may be staggered in a staggered pattern. At this time, the injection port 31c can be arranged between the adjacent contact rollers 32. With such a structure, the number and diameter of the contact rollers can be increased to improve the durability of the device, and the uniformity of water cooling can be ensured at the same time.

By contacting the work roll 27b and the backup roll 27a with the contact rollers 32 and 33 as described above, even if there is a slight change in the diameter of the work roll 27b or the backup roll 27a, it can be dealt with.

The drive device 35 is a drive device that presses the pressing head 31 so as to push it between the backup roll 27a and the work roll 27b. In this embodiment, the drive device 35 includes a drive source 36 and a cylinder 37. One end of the cylinder 37 is connected to the drive source 36, and the other end of the cylinder 37 is connected to a portion of the pressing head 31 opposite to the wedge-shaped tip side. As a result, the driving force generated by the driving source 36 can be transmitted to the pressing head 31 through the cylinder 37 to apply the pressing force to the pressing head 31.
The form of the drive device 35 is not particularly limited as long as the pressing force can be applied to the pressing head 31, and a known driving device can be applied.

Such a pressing device 30 is arranged as shown in FIGS. 2 and 3. That is, the first pressing portion 31a faces the backup roll 27a, the contact roller 32 contacts the surface of the backup roll 27a, the second pressing portion 31b faces the work roll 27b, and the contact roller 33 faces the work roll 27b. Arranged to contact the surface. At this time, the thin wedge-shaped tip of the pressing head 31 is positioned so as to face the contact portion side between the backup roll 27a and the work roll 27b.

When the pressing head 31 is pressed by the driving device 35 in the state where the pressing device 30 is arranged in this way, the pressing device 30 acts as follows. 7 and 8 are diagrams for explanation. FIG. 7 is a diagram illustrating a case where the pressing device 30 is not used, and FIG. 8 is a diagram illustrating a case where the pressing device 30 is used. Since the top and bottom can be considered to be symmetrical with the steel plate S in between, the work roll and the backup roll arranged on the upper side will be mainly described here.
When the pressing device 30 is not used, as shown in FIG. 7, as the steel plate S is rolled, a reaction force of magnitude a indicated by the arrow A is generated from the steel plate S with respect to the work roll. The backup roll receives a force of magnitude b indicated by arrow B from the contact portion with the work roll, and receives a force of magnitude c indicated by arrow C from the backup roll bearing portion. Here, when the rolling reaction force is much larger than the weight of the roll, the magnitudes a, b, and c of the force are all substantially equal. A force of the same magnitude acts as an action / reaction on the contact area between the work roll and the backup roll, but if this force becomes too large, the backup roll, which is weaker than the work roll, has a problem. It was.

On the other hand, when the pressing member 30 is used as shown in FIG. 8, a pressing force is applied so that the pressing head 31 approaches the contact portion between the backup roll 27a and the work roll 27b. The pressing force is such that the pressing head 31 has a wedge shape, so that the first pressing portion 31a presses the backup roll 27a in the direction indicated by the arrow B2 with the size of b2. Similarly, the second pressing portion 31b presses the work roll 27b in the direction indicated by the arrow B3 with the size of b3. Then, the pressing force by the pressing head 31 is received at the portion where the pressing member 30 is attached by transmitting the force of the magnitude b4 as shown by the arrow B4.

Here, considering the direction and magnitude of the force in the pressing head 31, it is as follows.
The vertical component of the force of magnitude b2 indicated by the arrow B2 acts in the direction of pushing the backup roll 27a upward as indicated by the arrow B2'. On the other hand, the vertical component of the force of magnitude b3 indicated by arrow B3 works in the direction of pushing down the work roll 27b downward as indicated by arrow B3'. Since all of these forces act in the direction of weakening the contact force generated between the backup roll 27a and the work roll 27b, as a result, the force due to the contact between the backup roll 27a and the work roll 27b indicated by the arrow B1 is large. The value is b1, and the magnitude b1 of the force is smaller than the magnitude b of the force due to the contact between the backup roll and the work roll shown by the arrow B in FIG. 7. As a result, the contact surface pressure (Hertz pressure) between the backup roll 27a and the work roll 27b can be reduced.

Here, the vertical component of the force received by the backup roll 27a from the contact portion with the work roll 27b and the force received from the pressing head 31 will be considered. Then, when the two force magnitudes b1 indicated by the arrow B1 and the force magnitude b2'indicated by the arrow B2'are summed up, the magnitude of the force received from the work roll by the backup roll indicated by the arrow B in FIG. It is the same as b. That is, even if the pressing member 30 is used in this way, the magnitude a of the force indicated by the arrow A and the magnitude c of the force indicated by the arrow C can be the same regardless of the presence or absence of the pressing member 30. Therefore, it is possible to reduce only the force generated at the contact portion between the backup roll 27a and the work roll 27b while keeping the rolling load the same.

On the other hand, considering the horizontal component of the force acting by the pressing head 31, the two force magnitudes b2 ″ indicated by the arrow B2 ″ and the force magnitude b3 ″ indicated by the arrow B3 ″. Since the two are in opposite directions and have the same size, they are balanced, so no force is generated in the horizontal direction. Therefore, even if the pressing member 30 is present, a force that hinders rolling is not generated.

As described above, according to the pressing member 30, the force transmission path is dispersed to the contact portion between the backup roll 27a and the work roll 27b while keeping the rolling load the same, as compared with the case where the pressing member 30 is not used. Since only the generated force is reduced and the contact surface pressure and the Hertz pressure are reduced accordingly, it is possible to prevent the backup roll from being damaged.

The degree of pressing pressure by the pressing device 30 can be adjusted as needed, and is not limited, but can be considered as follows, for example. That is, it can be said that even reducing the contact surface pressure between the backup roll and the work roll by 10% with respect to the case where there is no pressing device is sufficiently effective in suppressing fatigue fracture of the backup roll. Therefore, since the pressing devices are arranged on both the upstream side and the downstream side with respect to one backup roll, the contact surface pressure may be reduced by 5% on one side.
Currently, work roll benders for crown control operate between the work roll chock and the rolling mill housing, which is often designed in the range of 5% to 10% of the maximum load of the rolling mill, which is the same. It suffices if a certain degree of pressing force is secured. From this point of view, it can be assumed that a hydraulic device is used as a drive source, but it is possible to configure the pressing device without increasing the scale so much.
In the above embodiment, the pressing head integrated in the plate width direction has been described, but if the pressing head is divided in the plate width direction and can be individually controlled, it is possible to provide the crown control capability.

At that time, cooling water is injected from the injection ports 31c provided in the first pressing portion 31a and the second pressing portion 31b, and the backup roll 27a and the work roll 27b can be cooled at the same time.
When the diameter of the work roll is reduced, the number of contacts between the work roll and the steel plate is increased, so that heat transfer is increased and the surface area for cooling the work roll is reduced. Therefore, the work roll is generally cooled. The problem of shortage arises. If cooling is performed as in the present embodiment for such a problem, the insufficient cooling can be solved.
Since the injection area is smaller than that of cooling alone, the effect is small, but the effect of work roll cooling is sufficient because cooling can be performed on both the upstream side and the downstream side.
Further, this cooling water can be expected to have an effect of reducing friction between the first pressing portion and the backup roll, and the second pressing portion and the work roll, and can extend the life of the pressing device.

9A and 9B are views for explaining the second mode, FIG. 9A corresponds to FIG. 3, and FIG. 9B corresponds to FIG. 4A. The second embodiment is an example in which a pressing device 130 to which the pressing head 131 is applied is provided instead of the pressing head 31. Since the other aspects are the same as those of the first embodiment, the pressing head 131 will be described here.

The pressing head 131 also has a first pressing portion 131a facing the backup roll 27a and a second pressing portion 131b facing the work roll 27b. Therefore, the first pressing portion 131a has a curvature that has the same curvature as the outer circumference of the backup roll 27a, and the second pressing portion 131b has a curvature that has the same curvature as the outer circumference of the work roll 27b. I have.
The first pressing portion 131a and the second pressing portion 131b are arranged so as to approach each other toward the tip thereof (the side opposite to the driving device 35). This is similar to the form in which the outer peripheral surfaces approach each other as they approach the contact portion between the backup roll 27a and the work roll 27b. As a result, the pressing head 131 has a wedge shape that tapers as it approaches the tip.

The first pressing portion 131a and the second pressing portion 131b are curved as described above from the viewpoint of FIG. 9A, have a wedge shape, and appear in the plate width direction in FIG. 9B. As described above, the backup roll 27a and the work roll 27b are rectangular so that they can face each other over the entire length in the width direction (the second pressing portion 131b can be considered in the same manner as the first pressing portion 131a). Therefore, it is omitted.).

And in this embodiment, as can be seen from FIGS. 9 (a) and 9 (b), the contact roller is not provided. Therefore, in this embodiment, the first pressing portion 131a and the second pressing portion 131b come into contact with the backup roll 27a and the work roll 27b on the surface instead of the contact roller.

Further, the first pressing portion 131a and the second pressing portion 131b are provided with a plurality of cooling water injection ports 31c so that cooling water is provided from equipment (not shown) and water is injected from the injection ports 31c. It is configured. As a result, the backup roll 27a and the work roll 27b can be cooled at the same time. The cross-sectional shape and arrangement of the injection port 31c are not particularly limited and may be appropriately changed.
However, in this embodiment, as described above, the first pressing portion 131a and the second pressing portion 131b come into contact with the backup roll 27a and the work roll 27b on the surface, so that a drainage channel for cooling water from the injection port 31c is required. Become. Therefore, as shown in FIG. 9B, each injection port 31c is formed with a groove 131c that communicates with the outside of the pressing head 131. The sprayed water can be discharged from here.

A rolling mill provided with such a pressing device 130 also operates in the same manner as a rolling mill provided with the pressing device 30.

Although an example of applying the pressing device to the 4-stage rolling mill has been described here, the pressing device may be applied to the 6-stage rolling mill as shown in FIG. In the rolling mill 227, which is a 6-stage rolling mill, the work roll 27b, the intermediate roll 227a which is a second roll arranged in contact with the outer peripheral surface of the work roll 27b, and the outer peripheral surface of the intermediate roll 227a. A backup roll 27a, which is a first roll arranged in contact with the outer peripheral surface, is provided only on the surface. Then, in the pressing member 30, the first pressing portion 31a comes into contact with the backup roll 27a, which is the first roll farther from the steel plate S, and the second pressing portion 31b is closer to the steel plate S. It is arranged so as to come into contact with the intermediate roll 227a, which is the roll of 2.
As described above, the 6-stage rolling mill also has the same effect as described above. Although the pressing device is applied between the first roll and the second roll here, the pressing device may be applied between the work roll and the second roll.

As one example, a rolling mill having a work roll diameter of 500 mm, a backup roll diameter of 1500 mm, and a pressing device according to the pressing device 130 (FIGS. 9A and 9B) was prepared. The pressing devices are arranged at four locations according to the example of FIG.

The damage of the backup roll was evaluated when rolling was performed using this rolling mill with a rolling load of 4000 tons and rolling of 150 km in terms of coil length under the same conditions. The damage of the backup roll was evaluated by the presence or absence of cracks due to fatigue.

The composition of the steel material to be rolled is C: 0.12%, Mn: 2.5%, Si: 1%, Nb: 0.01%, Al: 0.03%, and the balance is Fe. And unavoidable impurities. The rolling temperature was 830 ° C.

The rolling was performed by rolling the plate thickness from 3.5 mm to 2.0 mm (rolling 1) and rolling the plate thickness from 3.2 mm to 2.0 mm (rolling 2).

For each of rolling 1 and rolling 2, the pressing force of the pressing head was changed by 100 tons from 0 to 500 tons, and the presence or absence of cracks in the backup roll was evaluated as described above. The graph of the result is shown in FIG. The horizontal axis is the pressing force of the pressing head, and the vertical axis is the maximum value of the contact surface pressure between the backup roll and the work roll.
Here, since the pressing head pressing force on the horizontal axis is the total pressing force of the upstream and downstream pressing devices arranged on one backup roll, the pressing force of one pressing device is half of that. The pressing pressure of the pressing head was obtained from the hydraulic pressure acting on the cylinder (hydraulic cylinder).
A longitudinal axis contact surface maximum value of pressure (Hertz pressure) sigma _max subtracts the vertical component force P ₂ is calculated from the pressing force to the roll diameter from the rolling load P _1, the width L of it contacts the rolls are The contact load P between the rolls per unit width is obtained by dividing by (Equation (1)), and the roll radii R ₁ , R ₂ and the roll longitudinal elastic modulus E _{1 of the} two rolls in contact with the contact load P are obtained. , E ₂ , Poisson's ratio ν ₁ , ν ₂ and the Hertz formula (Equation (2), Eq. (3)) was used.

In FIG. 11, those in which cracks were found in the backup roll were represented by “x”, and those in which no cracks were found in the backup roll were represented by “◯”. As shown in FIG. 1, when there was no pressing force by the pressing head, the Hertz pressure was high in both rolling 1 and rolling 2, and cracks due to fatigue were found in the backup roll. As the pressing force by the pressing head was increased, the Hertz pressure could be reduced in both rolling 1 and rolling 2.
Then, in the case of rolling 1, the pressing force by the pressing head was set to 300 tons or more, and in the case of rolling 2, the pressing force by the pressing head was set to 100 tons or more, so that cracks due to fatigue could be reliably avoided in the backup roll. ..
In addition, the work roll was not cooled sufficiently and the thermal expansion did not grow abnormally.

1 Hot-rolled steel sheet manufacturing equipment 10 Hot-finished rolling mill row 27 Rolling mill 27a Backup roll (first roll)
27b Work roll 30, 130 Pressing device 31, 131 Pressing head 31a, 131a First pressing part 31b, 131b Second pressing part 31c Injection port 32 Contact roller 33 Contact roller 40 Outer side cooling device 131c Groove 227a Intermediate roll (second) roll)

Claims (7)

Work roll and
A first roll arranged in contact with the outer peripheral surface of the work roll,
Pressing heads arranged on the upstream side and the downstream side of the work roll and in contact with the work roll and the first roll,
A drive device for pressing the pressing head from a position closer to the steel plate than the position where the first roll and the work roll come into contact with each other in a direction away from the steel plate is provided.
The pressing head
The first pressing portion in contact with the first roll and
It has a second pressing portion that comes into contact with the work roll, and has
The first pressing portion and the second pressing portion have a wedge shape so that the distance approaches the tip.
A rolling mill whose tip is arranged toward the side where the work roll and the first roll come into contact with each other. The rolling mill according to claim 1, wherein the first roll is a backup roll, which is a four-stage rolling mill including the work roll and the backup roll. A claim that at least one of the first pressing portion and the second pressing portion is provided with a contact roller, and the contact roller contacts at least one of the work roll and the first roll. The rolling mill according to 1 or 2. Work roll and
A second roll arranged in contact with the outer peripheral surface of the work roll,
With the first roll arranged in contact with the outer peripheral surface of the second roll,
A pressing head arranged on each of the upstream side and the downstream side of the work roll and contacting both of the rolls arranged in contact with the outer peripheral surface, and
A drive device for pressing the pressing head from a position closer to the steel sheet than the position where the first roll and the second roll come into contact with each other in a direction away from the steel sheet is provided.
The pressing head
Of the rolls arranged in contact with the outer peripheral surface, the first pressing portion that contacts the roll farther from the steel sheet and
It has a second pressing portion that comes into contact with the roll that is closer to the steel plate among the rolls that are arranged in contact with the outer peripheral surface.
The first pressing portion and the second pressing portion have a wedge shape so that the distance approaches the tip.
The tip is a rolling mill arranged so that the rolls arranged in contact with the outer peripheral surfaces are arranged toward the side in contact with each other. The first roll is a backup roll, the second roll is an intermediate roll, and a six-stage rolling mill including the work roll, the intermediate roll, and the backup roll.
The rolling mill according to claim 4, wherein the pressing head is arranged so as to come into contact with both the first roll and the second roll. At least one of the first pressing portion and the second pressing portion is provided with a contact roller, and the contact roller is a work roll, the first roll, and the second roll. The rolling mill according to claim 4 or 5, which is in contact with at least one. The rolling mill according to any one of claims 1 to 6, wherein at least one of the first pressing portion and the second pressing portion is provided with an injection port into which cooling water is injected.

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