JP2004306046A - 5-stage rolling mill and array of rolling mill, and rolling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a 5-stage rolling mill preferable for producing a hot-rolled steel plate of fine grained steel, an array of rolling mills including the 5-stage rolling mill, and a rolling method using the mills. <P>SOLUTION: The 5-stage rolling mill is composed so that a work roll 13 having a small diameter (around 500 mm or less) and an intermediate roll 14 having a small diameter are arranged on one side so as to apply the high rolling-reduction of ≥40% to a steel plate P. The work roll 13 having a small diameter, the roll 14 in contact with the roll 13, and rolls 15, 16 are not connected to a rotation driving means. The rotation driving means is connected to a work roll 11, which is arranged on the other side paired with the side where the rolls 13, 14 are arranged. The intermediate roll 14 is offset to the downstream side in the rolling direction, and the support roll 16 is pressed, in such a manner that the position of the roll 16 is adjustable, against the intermediate roll 14 from the downstream side in the rolling direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The invention according to the claim is a five-high rolling mill suitable for manufacturing a hot-rolled fine-grained steel sheet having a crystal grain size of a ferrite structure of about 10 μm or less (a rolling mill that performs rolling with five rolls per stand). And a rolling mill train including the same, and a rolling method using them.
[0002]
[Prior art]
The so-called hot-rolled fine-grained steel sheet with a fine structure mainly composed of fine-grained ferrite has excellent mechanical properties, and it has the effect of reducing the weight of equipment and facilities using it as a material, thereby reducing energy consumption. It has attracted the attention of the industrial world.
[0003]
There are Patent Documents 1 described below regarding the production of hot-rolled fine-grained steel sheets, and for example, Patent Document 2 regarding a five-high rolling mill.
[Patent Document 1] JP-A-2002-273501
[Patent Document 2] JP-A-62-38706
[0004]
Patent Document 1 discloses that a rolling mill including a small-diameter work roll (or a large-small-diameter work roll) having an equivalent roll diameter (average diameter of a pair of rolls) of about 500 mm is arranged in a plurality of subsequent stands. A hot rolling mill (rolling mill train) equipped to strongly cool a rolled sheet (steel sheet) at a plurality of appropriate locations is described. By performing sufficient cooling while applying a large reduction to the rolled sheet by a hot rolling mill including such a small-diameter (or different-diameter) work roll, the rolled sheet can be appropriately cooled despite the processing heat generated during rolling. By maintaining the temperature range, the structure is refined and the grain growth is prevented, thereby producing a hot-rolled steel sheet of fine-grained steel.
[0005]
Patent Document 2 describes that an extremely high rolling reduction can be obtained in a five-high rolling mill as shown in FIG. 8 configured by reducing one of the upper and lower work rolls to have a smaller diameter. In FIG. 8, reference numeral P denotes a rolled plate, reference numerals 71 and 73 denote work rolls, reference numeral 74 denotes an intermediate roll, reference numerals 72 and 75 denote backup rolls, and reference numerals 76 and 77 denote motors for rotating the work roll 71 and the intermediate roll 74, respectively. Attached rotation driving means.
[0006]
[Problems to be solved by the invention]
As a matter of course, it is possible to use a five-high rolling mill as the hot rolling mill described in Patent Document 1, but Patent Document 1 exemplifies a four-high rolling mill, No specific description is given as to what characteristics of a five-high rolling mill having the most appropriate characteristics for the production of. On the other hand, Patent Document 2 discloses that a five-high rolling mill as shown in FIG. 2 is suitable for high pressure, but what kind of rolling mill is used and how the fine-grained hot-rolled steel sheet is used Is not described at all.
[0007]
The claimed invention provides a five-high rolling mill, a rolling mill train including the same, and a rolling method using the same, which are preferable for producing a hot-rolled fine-grained steel sheet.
[0008]
[Means for Solving the Problems]
The five-high rolling mill according to claim 1 is characterized in that a small-diameter work roll and a small-diameter intermediate roll are arranged on one side, and a high-pressure reduction of 40% or more with respect to a rolled plate can be performed. . Since it is a five-high rolling mill, a backup roll (supporting roll) is provided outside the above-mentioned intermediate roll (on the side far from the work roll and the rolled plate), and another work roll is provided on the other side that is paired with them. Rolls are arranged, and the total number of rolls contributing to reduction is set to five.
In this specification, the “small diameter” of the roll refers to a roll having a diameter of about 500 mm or less. Therefore, in the present invention, the diameters of the work roll and the intermediate roll are about 500 mm or less. However, since the work roll receives a force from the rolled plate in the rolling direction (the direction in which the rolled plate is fed) although being supported by the intermediate roll, the roll diameter (the diameter of the work roll) is about 400 mm in terms of strength. It is preferable to make the above.
[0009]
Since the diameter of at least one of the work rolls of the pair is small, the five-high rolling mill can smoothly perform rolling with a high draft as described in Patent Document 2. Since the rolling load for realizing a specific rolling reduction becomes smaller as the diameter of the work roll becomes smaller, the smaller the diameter, the higher the rolling reduction with a lower rolling load. If the rolling load is reduced, the phenomenon that high-pressure reduction rolling cannot be performed due to the flattening of the roll is eliminated, and a high load is applied near the edge (widthwise end) of the rolled sheet, and the rolling roll is deformed flat. Therefore, the edge drop phenomenon due to this is also reduced.
[0010]
Since the five-high rolling mill having such a characteristic performs high-pressure reduction with a reduction ratio of 40% or more, by using the four-high rolling mill exemplified in Patent Document 1 described above, the fine-grain Enables production of rolled steel sheets. That is, any one of the exemplified four-high rolling mills arranged at the subsequent stage is replaced with the five-high rolling mill according to the present invention, and a plurality of appropriate rolling mills are formed in the same manner as described above while performing high-pressure reduction at a reduction ratio of 40% or more. If the rolled plate is strongly cooled at a suitable location, the rolled plate can be reduced in pressure while maintaining the rolled plate in an appropriate temperature range, and a fine-grained steel plate can be manufactured.
[0011]
The five-high rolling mill of this claim has the further advantage that it can be constructed by only slightly modifying the existing four-high rolling mill generally arranged in a conventional rolling mill train. This can be explained as follows.
B) A four-high rolling mill that achieves a normal rolling reduction (about 30%) that is not intended to manufacture fine-grained steel sheets generally uses a pair of work rolls having a diameter of about 700 to 1000 mm.
B) The five-high rolling mill according to the present invention has a small-diameter work roll and a small-diameter intermediate roll arranged on one side as described above, and the sum of the diameters of the work roll and the intermediate roll is equal to that in a general case. It is not much larger than the diameter of the work roll (about 700 to 1000 mm as described in (a) above).
C) Therefore, in the above-mentioned general rolling mill, while using the rolling mill housing (a part forming a window) as it is, only one work roll is replaced with a small-diameter work roll and a small-diameter intermediate roll, so that it is simple and low. It is also possible to configure this five-high rolling mill at a low cost.
[0012]
In the five-high rolling mill according to the second aspect of the present invention, the small-diameter work roll and the roll in contact with the small-diameter work roll (that is, the small-diameter intermediate roll and its backup roll, or a support roll described later) are particularly provided with a rotation driving means. The rotation driving means is connected to the other work roll of the pair without being connected.
[0013]
In the five-high rolling mill according to the present invention, in addition to the fact that at least one of the work rolls has a small diameter and the equivalent roll diameter is small, only the other work roll forming a pair is rotated and driven to rotate. Since a shear force is applied to the sheet, it is particularly advantageous for performing a high rolling reduction with a low rolling load, and for example, a 50% rolling reduction is not difficult. For this reason, large reduction rolling or the like for producing a hot-rolled steel sheet can be performed with a relatively small rolling load. Further, since the rolling load is small, inconvenience due to roll flattening and edge drop can be easily avoided.
[0014]
The five-high rolling mill according to claim 3 is characterized in that a pair of work rolls including the small-diameter work roll described above have a CVC function. The CVC function refers to a function in which a roll (CVC roll) whose outer diameter continuously changes in the axial direction moves in the axial direction to control the change of the roll gap shape (see FIG. 4).
[0015]
When performing high-load rolling that results in high-pressure reduction, in addition to the work roll sagging and easily reducing the shape accuracy of the rolled plate, the heat load of the roll is increased based on the processing heat of the rolled plate, and the middle The thermal crown whose diameter increases at the portion is likely to occur. Depending on the degree of the thermal crown, it is difficult to eliminate the thermal crown only by cooling the roll, and the shape of the rolled plate may be deteriorated and stable threading may be difficult. In addition, when rolling is performed at a high reduction rate, wear of the rolls becomes severe, which also tends to reduce the shape accuracy of the rolled plate.
However, in the five-high rolling mill of this claim, since the pair of work rolls have the CVC function, the crown control can be performed by appropriately changing the roll gap shape by the function. Therefore, despite the above circumstances, the shape of the rolled plate can always be kept good. When a bending function (a function of changing the roll gap shape by applying a bending moment to the roll) is added to the pair of work rolls, the control performance of the shape accuracy is further improved.
[0016]
The five-high rolling mill according to claim 4, in particular, a support roll (a roll mainly for supporting in a horizontal direction) so as to be pressed against the small-diameter work roll or the small-diameter intermediate roll from a downstream side in the rolling direction. Are arranged.
[0017]
When the support roll is used in this manner, the small-diameter work roll can be reinforced so as to resist a force acting horizontally (downstream in the rolling direction) from the rolled plate. For example, when the support roll is pressed against the small-diameter work roll from the downstream side in the rolling direction (the case illustrated in FIG. 7A), the support roll acts on the work roll so as to directly resist the horizontal force. I do. When a small-diameter intermediate roll is offset to the downstream side in the rolling direction and is brought into contact with the work roll, and a support roll is pressed against the intermediate roll from the downstream side in the rolling direction (the case illustrated in FIG. 1 and the like), the intermediate roll passes through the intermediate roll. The pressing force of the support roll transmitted to the work roll (the horizontal component force) reduces (cancels) the horizontal force applied to the work roll.
Therefore, according to the five-high rolling mill of the present invention, the diameter of the work roll can be made particularly small, and as a result, it is possible to more smoothly perform high-pressure reduction with a low rolling load.
[0018]
The five-high rolling mill according to claim 5, wherein the small-diameter intermediate roll is offset to the downstream side in the rolling direction, and the support roll is pressed against the intermediate roll from the downstream side in the rolling direction, and the support roll is provided. Is adjustable in the pressing direction (that is, the direction substantially along the rolling direction). FIG. 5 shows an example in which the position of the support roll is adjusted according to the present invention.
[0019]
In such a five-high rolling mill, crown control can be performed on a work roll. By adjusting the position of the support roll in the pressing direction, the bending shape in the horizontal plane of the intermediate roll between the backup roll and the work roll changes, and accordingly, the work roll becomes, for example, as shown in FIG. This is because, as shown in (e) (the sign of the work roll is 13), the bending shape is changed in the vertical plane. If the crown control can be performed on the work roll, the shape of the rolled plate can also be favorably controlled.
[0020]
When a hot-rolled fine steel sheet is manufactured, it is usual to provide a cooling spray and a means for removing (draining) the cooling water from the work roll because the heat load of the work roll is high as described above. . In many cases, a means for supplying a lubricant to the surface of the work roll in consideration of the mechanical load is provided. Therefore, the rolling mill according to the present invention, in which the support roll is pressed against the intermediate roll instead of the work roll, facilitates the arrangement of the support roll, and smoothly cools and drains the entire peripheral surface of the work roll. Therefore, it can be said that it also has a technical merit that the supply of the lubricant is not hindered.
[0021]
In the five-high rolling mill according to claim 6, in particular, the small-diameter work roll and the small-diameter intermediate roll are replaced with one work roll having the same diameter as the work roll on the other side forming a pair with them. Thus, a change to a four-high rolling mill is enabled. The five-high rolling mill F4 shown in FIG. 6 is an example in which such a change is made possible. FIG. 6 (a) shows a state of a five-high rolling mill, and FIG. 6 (b) shows a state of changing to a four-high rolling mill. Is shown.
[0022]
When such a change is made possible, in the state of a five-high rolling mill using a small-diameter work roll and a small-diameter intermediate roll, high-pressure rolling with a reduction ratio of 40% or more is performed, and the two rolls are replaced with the one roll. When a four-high rolling mill is used instead of a work roll, general rolling with a rolling reduction of 40% or less can be performed.
[0023]
General rolling at a low rolling reduction (40% or less) may be performed in a state of a five-high rolling mill.
-The tip of the rolled plate may not be easily bitten by the small-diameter work roll in the five-high rolling mill.
-Since the outer diameters of the pair of upper and lower work rolls are different, it is difficult to match the peripheral speeds, and therefore, the vicinity of the leading end of the rolled plate may be bent upward or downward and fed. To prevent this, it is important to match the peripheral speeds of the pair of work rolls. However, if only one of the pair is driven to rotate, the upper and lower work rolls must be kissed (contacted) once. A complicated operation of rotating the non-driven roll at an appropriate speed and then releasing the kiss is required. Further, when both rolls are driven, it is difficult to control the rolls to have the same peripheral speed even though the outer diameters are different (and the degree of progress of wear on the outer peripheral surface is different). Will be needed.
[0024]
If the rolling is performed at a low rolling reduction after changing to a four-high rolling mill, there is no inconvenience as described above. That is, since the equivalent roll diameter is larger than that of the five-high rolling mill and a pair of work rolls having the same diameter are used, the leading end of the rolled plate is easily bitten, and both of the pair of work rolls are used. It is easy to rotate at the same peripheral speed.
[0025]
A rolling mill row according to claim 7, wherein the above-mentioned five-high rolling mill is provided in a subsequent stand including the final stage, and a curtain wall type for a rolled plate is provided on the output side of a plurality of subsequent rolling mills including the final stage. A cooling means is provided. The curtain wall type cooling means refers to a cooling means of a type in which a large amount of cooling water is flowed in a laminar flow from above and below like a curtain and applied to the upper and lower surfaces of the rolled plate over the entire width. The rolling mill train A shown in FIGS. 2 and 3 is an example of a rolling mill train according to the present invention.
[0026]
As described in Patent Document 1 mentioned above, the conditions for producing a hot-rolled fine-grained steel sheet are such that a large change in temperature is applied to the rolled sheet while sufficiently reducing the temperature change due to the heat generated during the rolling. It is to suppress by cooling. The rolling mill row according to the present invention is provided with the above-mentioned five-high rolling mill in a subsequent stand having a strong influence on the metallographic structure, and a curtain wall type cooling means arranged on the exit side of the rolling mills in a plurality of subsequent stands. is there. The above-mentioned five-high rolling mill can smoothly perform rolling with a high rolling reduction, and the curtain wall type cooling means has a high cooling capacity for the rolled plate, and sets the rolled plate during and after rolling to an appropriate temperature range. Is enough to keep. Therefore, according to the rolling mill train of this claim, it is possible to reliably and smoothly refine the structure of the steel sheet, that is, to manufacture a hot-rolled steel sheet of fine-grained steel.
[0027]
The rolling method according to claim 8 is a rolling method using the five-high rolling mill according to claim 6, characterized in that the following (1) and (2) are performed.
{Circle around (1)} When using small-diameter work rolls and small-diameter intermediate rolls, only the work rolls on the other side that are paired with them are rotationally driven to perform high-pressure reduction with a reduction ratio of 40% or more.
{Circle around (2)} When replacing the small-diameter work roll and the small-diameter intermediate roll with the one work roll described above and changing to a four-high rolling mill, the pair of work rolls on both sides are driven to reduce the rolling reduction to 40% or less. I do.
[0028]
According to this rolling method, the above-mentioned function of the rolling mill according to claim 6 is actually exhibited, so that a hot-rolled steel sheet (in the case of the above (1)) and a general metal sheet that is not a fine-grained steel sheet (In the case of the above (2)) can be appropriately selected for production. When a general metal plate is manufactured by the above (2), a pair of work rolls having a larger diameter and an equal diameter are used than in the case of (1), so that a) the leading end of the rolled plate is easily bitten. B) a pair of work rolls can be driven to rotate at the same peripheral speed to easily prevent an inconvenience in which the vicinity of the leading end of the rolled sheet is bent upward or downward and fed.
[0029]
The rolling method according to claim 9 is a rolling method using the rolling mill train according to claim 7, wherein rolling is performed so that the cumulative strain becomes 0.6 or more, and a plurality of stands at a subsequent stage including a final stage are formed. It is characterized in that a curtain wall type cooling means is used for the rolled plate on the outlet side of the rolling mill. The “distortion” refers to the thickness h of the rolled plate at the entrance side of each stand. ₀ And the thickness h on the delivery side ₁ Divided by the average thickness of both
ε = (h ₀ -H ₁ ) / ｛(H ₀ + H ₁ ) / 2｝
Say. The term “cumulative distortion” refers to the distortion in each of the three subsequent stands (there may be two stands) among the above stands (stands upstream of them are ignored because they have a small influence). Weighted integration taking into account the strength of the effect on _n , Ε _n-1 , Ε _n-2 When
ε _c = Ε _n + Ε _n-1 / 2 + ε _n-2 / 4
Ε represented by _c Shall be referred to. As the temperature of the rolled plate, for example, the plate surface temperature (rolling end temperature) measured immediately after the final stand is Ar ₃ It is preferable to keep the temperature within a range of ± 50 ° C. across the transformation point.
[0030]
According to this rolling method, the fine-grained steel hot-rolled steel sheet can be manufactured smoothly by utilizing the function of the rolling mill train of claim 7. While rolling at a high pressure reduction rate of 0.6 or more, the rolled sheet is strongly cooled by curtain wall type cooling means on the exit side of a plurality of subsequent stands, so that heat generated during rolling is deprived of an appropriate temperature. While maintaining the temperature, the rolled plate immediately after rolling can be strongly cooled to reduce the crystal grain size of the ferrite structure to, for example, about 10 μm or less. When the cumulative strain is further increased to 0.9 or more, the crystal grain size can be reduced to about 4 μm or less.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
One embodiment of the present invention is shown in FIGS. FIG. 1 is a side view showing a rolling mill F4, FIG. 2 is a side view of a rolling mill row A including the rolling mill F4, and FIG. 3 shows the vicinity of a final rolling mill F6 in the rolling mill row A. It is a side view. FIG. 4 is a view for explaining a CVC function in the rolling mill F4 and the like, FIG. 5 is a view showing a crown control function by the support roll 16 in the rolling mill F4 and the like, and FIG. It is a figure which shows that it changes between the state of a rolling mill (FIG. 6 (a)) and the state of a four-high rolling mill (the same (b)).
[0032]
The rolling mill F4 in FIG. 1 is for hot rolling of the steel sheet P included in the rolling mill row A in FIG. 2, and is a five-high rolling mill in which a total of five rolling rolls involved in reduction are arranged. A work roll 11 and a backup roll 12 are provided below the pass line of the rolled plate, that is, the steel sheet P, and a work roll 13, an intermediate roll 14, and a backup roll 15 are arranged above the pass line in this order. The five rolls are arranged in a window 10a in the rolling mill housing 10, and a vertical pressing force is applied in a vertical direction by a pressing means (a hydraulic cylinder or the like, not shown) provided at an upper portion or a lower portion of the housing 10. The steel sheet P passed between the rolls 11 and 13 is rolled. Specifically, both ends (bearing box) of one of the backup rolls 12 and 15 are fixed at a fixed height in the housing 10, and both ends (bearing box) of the other are connected to the screw-down means to move up and down. Enable displacement. By bringing the outer peripheral surfaces of the body portions into contact between the work roll 11 and the backup roll 12 and between the work roll 13 and the intermediate roll 14 and the backup roll 15, The rolling force is transmitted between the work rolls 11 and 13.
[0033]
The diameters of the backup rolls 12 and 15 in the rolling mill F4 are both 1600 mm, while the diameters of the body portions of the work rolls 11 and 13 and the intermediate roll 14 are set to 800 mm, 500 mm, and 350 mm, respectively. Of the five rolls, the intermediate roll 14 offsets the position of its axis to the downstream side in the rolling direction (the direction of the white arrow in FIG. 1), and attaches the downstream side to the outer peripheral surface of its body. From the support roll. The offset amount of the intermediate roll 14 (the horizontal distance from the axis of the other roll to the axis of the intermediate roll 14) is about 30 mm, and the support roll 16 has a body length shorter than the width of the steel plate P (the work roll 13 or the like). The length of the intermediate roll 14 is set to be equal to or less than half the length thereof, and the position thereof can be adjusted in the pressing direction (generally the rolling direction) by moving means (not shown) including a hydraulic cylinder or the like. In addition, the offset amount of the intermediate roll 14 is not limited to the above-mentioned 30 mm, but is determined in a range of about 10 to 50 mm (that is, the contact point between the intermediate roll 14 and the support roll 16 on the work roll 11 is 1 ° to 1 ° above the axis). It should be located at an angle position downstream of about 10 °).
[0034]
The lower work roll 11 is connected to a rotation drive means (not shown) such as a motor, but the upper work roll 13 and the rolls 14, 15, 16 in contact therewith are not connected to the rotation drive means. As described above, the work roll 13 has a small diameter of 500 mm, the equivalent roll diameter of both work rolls 11 and 13 is also small as 650 mm, and a shear force is applied to the steel sheet P in order to rotate only one of the work rolls 11. Since it can act, the rolling mill F4 can perform a high rolling reduction (for example, a rolling reduction of 50%) with a relatively small rolling force. Since the rolling load is small, there is no inconvenience due to roll flattening or edge drop.
[0035]
The rolling mill row A in FIG. 2 is a 6-stand type hot finishing rolling mill including the above rolling mill F4, and is configured as in the following a) to f). That is,
a) Four-high rolling mills F1 to F3 are arranged in tandem in the first three stands including the foremost part. In these four-high rolling mills, work rolls 1.3 having a diameter of about 700 mm and backup rolls 2.4 having a diameter of about 1300 mm are vertically arranged as shown in the figure.
[0036]
b) In the latter half stand including the last stage, the rolling mill F4 shown in FIG. 1 is used as a fourth stand, and rolling mills F5 and F6 having the same roll set as the rolling mill F4 are provided behind the rolling mill F4. Place in tandem in order. In any one of these rolling mills F4 to F6, since the work roll 13 has a small diameter, rolling at a high reduction ratio can be performed without particularly increasing the rolling force. The stand spacing of all six stands including the rolling mills F1 to F3 in the first half is equal to about 5.5 m.
[0037]
c) Curtain wall type cooling means 41, 42, 43 are arranged on each outlet side of the three stand rolling mills F4 to F6 arranged in the latter half. As shown in FIG. 3, the cooling means 42 has a large amount of room temperature cooling water in a laminar flow state from the upper and lower headers 42a and 42b toward the entire width surface of the steel sheet P (curtain wall shape; thickness is 10 mm or more). And the optimum thickness is 16 mm), thereby cooling the steel sheet P strongly. The cooling water amount is 100 to 500 m per unit width (1 m) of the steel sheet P. ³ / H within the range, and the temperature drop of the steel sheet P due to cooling is set to 20 ° C./sec or more. Normally 350m per unit width (including the following examples) ³ / H cooling water is used, and the temperature drop of the steel sheet P in that case is 60 to 80 ° C / sec when the product of the sheet thickness x speed is 1200 mm · mpm (40 ° C / sec). The above configuration and function are the same for the other cooling means 41 and 43 shown in FIG. By using such cooling means 41, 42, and 43, even if high-pressure rolling with intense processing heat is performed in the rolling mills F4 to F6, the temperature rise of the steel sheet P due to the rolling is suppressed, and the metal structure of the steel sheet P is reduced. Miniaturization and prevention of grain growth can be realized. In addition, also in a run-out table (not shown) provided downstream of the rolling mill row A in FIG. 2, the steel sheet P is cooled with cooling water at a rate of 10 ° C./sec or more in order to prevent grain growth.
[0038]
d) On the exit side of the rolling mill F6 which is the last stand of the rolling mill row A, a water jet spray 46 is disposed at a distance of several hundred mm to 1 m from the curtain wall type cooling means 43. The cooling means 43 is for removing the cooling water placed on the upper surface of the steel plate P. As shown in FIG. 3, the spray 46 is applied at a rate of 10 kg / cm so that the angle between the spray 46 and the upper surface of the steel plate P is 50 to 80 °. ² A plurality of nozzles 46a that blow out front and rear pressurized water at a rate of 300 liters per minute are provided (spaced in the length direction of the steel sheet P and spaced in the width direction thereof). Each nozzle 46a blows out water so as to spread in the width direction of the steel plate P, and the spread angle in the width direction of the steel plate P is preferably 15 to 30 °, and the spread angle in the length direction is preferably 1 to 10 °. If such a water spray 46 is used, the cooling water placed on the steel sheet P can be smoothly removed by the action of the cooling means 43 and the like, and the various types of measuring instruments on the downstream side thereof can be used to measure the rolled steel sheet P. Various measurements can be appropriately performed.
[0039]
e) A lubricant supply unit is arranged for each work roll of all rolling mills F1 to F6 in rolling mill row A. The means includes, for example, an injection port facing the surface of the work rolls 11 and 13 (or work rolls 1 and 3 in FIG. 2) as indicated by reference numerals 23 and 26 in FIG. Consists of As the lubricant, grease containing fine solid lubricants such as calcium phosphate, mica, calcium carbonate and the like is used. By the combination of the solid fine particles, the friction coefficient μ is increased to about 0.28 between each work roll and the steel sheet P when the lubricant is used, but the wear on the roll surface is suppressed, and the shape of the steel sheet P is reduced. It is easy to keep long and good. Since the solid fine particles are contained not in the mineral oil but in the grease, there is also an advantage that the solid fine particles are supplied so as to be always uniformly dispersed on the roll surface.
[0040]
f) For each work roll of all the rolling mills F1 to F6, as shown in FIG. 3, an injection nozzle (for example, reference numerals 21 and 24) for roll cooling water and a drain plate (for example, reference numeral) for removing the cooling water therefrom. 22 and 25) are arranged.
[0041]
In the rolling mill train A shown in FIGS. 2 and 3 described above, the heated steel sheet P is subjected to sufficient cooling while being subjected to high-pressure rolling so that the cumulative strain becomes 0.6 or more, so that the temperature thereof is appropriately adjusted. It is possible to manufacture a hot-rolled fine-grained steel sheet having a ferrite grain size of 10 μm or less. In this case, it is possible to control the shape of the steel sheet P satisfactorily in spite of rolling with a high rolling reduction. The reason why the shape can be made good can be explained as follows.
[0042]
The first reason is that the rolling mills F4 to F6 provided in the latter half are so-called CVC mills, each having the CVC function shown in FIG. That is, the work rolls 11 and 13 of each of the rolling mills F4 to F6 are provided with a crown (CVC, that is, a continuous change in diameter) as shown in FIG. 4A, and as shown in FIGS. 4B and 4C. The upper and lower work rolls 11 and 13 can be simultaneously moved (shifted) in opposite axial directions. By performing such a shift, the positional relationship between the work rolls 11 and 13, that is, the roll gap can be adjusted as shown in the figure. The maximum shift amount of each of the work rolls 11 and 13 is about ± 100 mm.
[0043]
In addition, it is also preferable that the rolling mills F1 to F3 arranged in the first half be configured as such a CVC mill. In consideration of the fact that thermal crowns and the like due to the heat generated during processing are likely to be generated in the subsequent rolling mills F4 to F6, the crowns are corrected in advance by the preceding rolling mills F1 to F3, and the middle drawing of the steel sheet P is reduced. is there.
[0044]
The second reason why the shape of the steel sheet P is favorably controlled in the rolling mill row A is that the crown control by the intermediate roll 14 and the support roll 16 can also be performed in the rolling mill F4 or the like as shown in FIG. is there. In the rolling mill F4 (and the rolling mills F5 and F6), as described above (FIG. 3), the injection ports 23 and 26 for supplying the lubricant to the work rolls 11 and 13 and the injection nozzles 21 and 24 for the water for cooling the rolls. In order to attach the draining plates 22 and 25 and the like, the intermediate roll 14 with little interference is offset toward the downstream, and the support roll 16 is pressed against it. The length of the support roll 16 is short, and the position of the support roll 16 can be adjusted in the pressing direction as described above by a moving means (not shown). The crown control by the support roll 16 and the like can be performed as follows.
[0045]
When the support roll 16 shown in FIG. 5A is moved to the upstream side during rolling, for example, as shown in FIG. 5B, and the vicinity of the center of the intermediate roll 14 is brought close to just above the work roll 13, the support roll 16 The roll 13 is pushed in the middle by the intermediate roll 14 and bends so as to project downward as shown in FIG. Conversely, as shown in FIG. 5D, when the support roll 16 is moved to the downstream side and the vicinity of the center of the intermediate roll 14 is moved away from directly above the work roll 13, the work roll 13 is moved by the rolling load as shown in FIG. ) And bend upward to become convex. If the roll gap between the work rolls 11 and 13 is adjusted in this manner, the crown control of the steel sheet P can be favorably performed over a wide range together with the CVC function described above.
[0046]
Although the rolling mills F4 to F6 in the rolling mill row A are five-high rolling mills including the small-diameter work rolls 13 as described above, each of the rolling mills F4 to F6 is a four-high rolling mill shown in FIG. Can be used by switching. That is, as shown in FIG. 6A, the work roll 13 and the intermediate roll 14 used as a five-high rolling mill are replaced with work rolls 33 having a larger diameter and the same diameter as the work roll 11. The rolling rolls 11 to 15 in the rolling mills F4 to F6 are easily replaceable as a normal function in rolling mills in general because the body surface needs to be repeatedly polished. Moreover, the sum of the body diameters of the work roll 13 and the intermediate roll 14 is 850 mm, and the difference from the body diameter (800 mm) of the work roll 33 to be replaced is small. Therefore, in the rolling mills F4 to F6, the housing 10 and its window 10a are not changed at all, and the same rolling-down means is used, and a liner is appropriately added in the rolling-down means or the initial rolling-down amount is slightly changed. Only by this means, it is possible to switch between the state of the five-high rolling mill (FIG. 6 (a)) and the state of the four-high rolling mill (the same (b)). Since the lower rolls 11 and 12 are used without changing the diameter, there is naturally no change in the pass line height.
[0047]
The rolling mills F4 to F6 perform the high-pressure reduction as described above in the state of the five-high rolling mill to enable the production of the fine-grained steel sheet, but as shown in FIG. Is not suitable for such production. This is because it is difficult to increase the rolling reduction because the diameters of the work rolls 11 and 33 are both large. Therefore, in the case of a four-high rolling mill, normal rolling with a rolling reduction of about 30% is performed in each of the rolling mills F4 to F6, and the rolling mill row A does not produce a fine-grained steel sheet. In such a case, the upper and lower work rolls 11 and 33 are connected to a rotation driving means (not shown) and are rotated at a constant speed. Then, the tip of the steel sheet P is easily bitten, and the disadvantage that the steel sheet P is bent upward or downward and sent due to a difference in peripheral speed between the work rolls does not easily occur. In addition, when the rolling mills F4 to F6 are in the state of a four-high rolling mill, since the processing heat generated under high pressure is small, the cooling of the steel sheet P is performed only on the exit side of the rolling mill F6 as a final-stage stand. In many cases, it is sufficient to use the second cooling means 43.
[0048]
In the examples of FIGS. 1 to 6, the support roll 16 is pressed against the intermediate roll 14, but a five-high rolling mill may be configured by pressing the support roll against the work roll. The rolling mill f4 in FIG. 7 (a) is an example thereof. A work roll 51 (having a body diameter of 700 mm) and a backup roll 52 (1300 mm) are provided below the pass line of the steel sheet P, and are provided above the pass line. A work roll 53 (400 mm), an intermediate roll 54 (500 mm), and a backup roll 55 (1300 mm) are disposed on the outer periphery of the body of the work roll 53 and a support roll 56 (350 mm in diameter) slightly above the downstream side. Press. The support roll 56 reinforces the thinnest work roll 53 among the five rolls to prevent the work roll 53 from sagging downstream in the rolling direction.
[0049]
Also in the rolling mill f4 in FIG. 7A, it is easy to replace the small-diameter work roll 53 and the intermediate roll 54 with one work roll 63 as in FIG. It is. If a work roll 63 having the same diameter (700 mm) as the lower work roll 51 is used above, there is no large difference in the total diameter compared with the case where the small-diameter work roll 53 and the intermediate roll 14 are used (FIG. This is because the housing and the pressing-down means can be used as they are in the same manner as in the above-described example (FIG. 6) because the middle dimension h, that is, the difference in height of the upper backup roll 55 does not exceed 200 mm. In the case of FIG. 7B, when the diameters of the work rolls 51 and 63 are set to the same diameter of about 700 mm and both are driven to rotate, the tip of the steel sheet P is easily bitten, and the steel sheet P faces upward or downward. There is also an advantage that the inconvenience of being bent and sent is prevented.
[0050]
【The invention's effect】
According to the five-high rolling mill described in the first aspect, high-pressure rolling with a rolling reduction of 40% or more can be performed smoothly while reducing flattening and edge drop phenomenon of the roll. Therefore, if this rolling mill is appropriately arranged in the rolling mill row and the rolled plate is appropriately cooled, it is possible to produce a hot-rolled fine-grained steel sheet having a ferrite grain size of about 10 μm or less. Further, the five-high rolling mill can be configured simply and at low cost by slightly modifying an existing four-high rolling mill arranged in a general rolling mill row.
The five-high rolling mill according to the second aspect is particularly advantageous in performing high-pressure reduction with a low rolling load, and can produce a fine-grained steel hot-rolled steel sheet more smoothly.
[0051]
Furthermore, in the five-high rolling mill according to claim 3, when performing high-load rolling, despite the fact that the work roll is likely to bend or generate a thermal crown, preferable shape control can be performed, It is possible to obtain a hot-rolled fine-grained steel sheet having high shape accuracy.
[0052]
In the five-high rolling mill according to the fourth aspect, the small-diameter work roll can be appropriately reinforced so as to resist the force acting horizontally. Therefore, the diameter of the work roll can be further reduced, and the rolling at a high pressure reduction rate with a low rolling load can be performed more smoothly.
In the five-high rolling mill according to the fifth aspect, the shape of the rolled plate can be favorably controlled by performing the crown control of the work roll by adjusting the position of the support roll. There is also an advantage that smooth cooling, drainage, lubricant supply, and the like to the work roll are not hindered.
[0053]
In the case of the five-high rolling mill according to the sixth aspect, the type of the rolling mill can be changed by exchanging rolls, so that both high-pressure reduction rolling and other general rolling can be smoothly performed. When performing general rolling, the leading end of the rolled plate is easily bitten between the work rolls, and the vicinity of the leading end of the rolled plate is easily prevented from being bent upward or downward and fed.
[0054]
According to the rolling mill train described in claim 7, it is possible to reliably and smoothly manufacture a fine-grained steel hot-rolled steel sheet.
According to the rolling method described in claim 8, the function of the rolling mill according to claim 6 is actually exerted, and a hot-rolled fine-grained steel sheet and a general non-fine-grained steel sheet are appropriately selected. It becomes possible to manufacture.
According to the rolling method according to the ninth aspect, it is possible to smoothly manufacture a hot-rolled fine-grained steel sheet by utilizing the function of the rolling mill train according to the seventh aspect.
[Brief description of the drawings]
FIG. 1 is a side view showing a rolling mill F4 according to an embodiment of the present invention.
FIG. 2 is a side view schematically showing the entire rolling mill row A including the rolling mill F4 of FIG.
FIG. 3 is a side view showing the vicinity of a final rolling mill F6 in the rolling mill row A of FIG. 2;
FIGS. 4A, 4B, and 4C are schematic diagrams for explaining a CVC function in a rolling mill F4 and the like.
FIG. 5 is a schematic diagram showing a crown control function using a support roll 16 in a rolling mill F4 or the like, and FIG. 5A is a side view showing a roll arrangement. (B) is a view of the work roll 13, the intermediate roll 14 and the support roll 16 when the support roll 16 is moved to the upstream side in the rolling direction as viewed from above, and (c) is in the state of (b). It is the figure which looked at certain work rolls 11 and 13 and steel plate P from the rolling direction downstream. (D) is a top view of the work roll 13 and the like when the support roll 16 is moved downstream in the rolling direction, and (e) is a work roll 13 and the like in the state (d). FIG. 3 is a view of the roller as viewed from the downstream side in the rolling direction.
FIG. 6 is a schematic diagram showing that a rolling mill F4 (or F5 or F6) is changed between a state of a five-high rolling mill (FIG. 6A) and a state of a four-high rolling mill (FIG. 6B). FIG.
FIG. 7 is a view showing a roll arrangement of a rolling mill f4 of another embodiment according to the embodiment of the present invention. FIG. 7 (a) shows a state where a five-high rolling mill is used, and FIG. 7 (b) shows a state where a four-high rolling mill is used. Indicates the status.
FIG. 8 is a side view schematically showing a roll arrangement in a conventional five-high rolling mill.
[Explanation of symbols]
A Rolling mill train
F4 / F5 / F6 rolling mill
P steel plate (rolled plate)
10 Housing
11.13 Work roll
12.15 Backup Roll
14 Intermediate roll
16 Support Roll
41, 42, 43 Curtain wall type cooling means
f4 rolling mill
51 ・ 53 Work roll
52 ・ 55 Backup Roll
54 Intermediate roll
56 Support Roll

Claims (9)

A five-high rolling mill characterized in that a small-diameter work roll and a small-diameter intermediate roll are arranged on one side so that a high reduction of 40% or more can be performed on a rolled plate. The five-stage rolling according to claim 1, wherein the small-diameter work roll and the roll contacting the small-diameter work roll are not connected to the rotation driving means, but the other side of the work roll is connected to the rotation driving means. Machine. The five-high rolling mill according to claim 1, wherein a pair of work rolls including the small-diameter work roll have a CVC function. The five-high rolling mill according to any one of claims 1 to 3, wherein a support roll is disposed so as to be pressed against the small-diameter work roll or the small-diameter intermediate roll from a downstream side in a rolling direction. The small-diameter intermediate roll is offset to the downstream side in the rolling direction, the support roll is pressed against the intermediate roll from the downstream side in the rolling direction, and the position of the support roll can be adjusted in the pressing direction. The five-high rolling mill according to any one of claims 1 to 4, wherein By replacing the small-diameter work roll and the small-diameter intermediate roll described above with a single work roll having the same diameter as the work roll on the other side forming a pair with the small-diameter work roll, it is possible to change to a four-high rolling mill. The five-high rolling mill according to any one of claims 1 to 5, wherein A five-stage rolling mill according to any one of claims 1 to 6, which is provided in a subsequent stand including the last stage, and a curtain wall type cooling means for a rolled plate on an output side of a plurality of subsequent stands including the last stage. A rolling mill train, comprising: A rolling method using a five-high rolling mill according to claim 6,
When using small-diameter work rolls and small-diameter intermediate rolls, only the other side work roll that is paired with them is rotationally driven to perform a high-pressure reduction at a reduction ratio of 40% or more, and a small-diameter work roll and a small-diameter intermediate roll are used. A rolling method characterized in that when the intermediate roll is replaced with the one work roll and changed to a four-high rolling mill, the work rolls on both sides forming a pair are driven to perform a reduction at a reduction ratio of 40% or less. A rolling method using the rolling mill train according to claim 7,
A rolling method, wherein rolling is performed so that the cumulative strain becomes 0.6 or more, and a curtain wall type cooling means is used for a rolled plate on the exit side of a plurality of stands including a final stage.

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