JP2010131645A - Method of hot-rolling material to be rolled - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of hot-rolling a material to be rolled, by which the difference between the amounts of scratching on the surface side and the back side of the material to be rolled is minimized when rolling both end sides in the longitudinal direction of the material to be rolled. <P>SOLUTION: When rolling both the end sides in the longitudinal direction of the material to be rolled with a rolling mill having upper and lower rolling rolls, the adjustment of the peripheral speed for adjusting the difference of the peripheral speed between the upper and the lower rolling rolls is performed so that the difference of the amounts of scratching formed on the surface and the back faces of the material to be rolled when performing the rolling is not more than a prescribed value and also the adjustment of the peripheral speeds of the rolls is performed in the range of 100-500 mm from the end part of entering side of the material to be rolled. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a hot rolling method of hot rolling both longitudinal ends of a material to be rolled such as a slab.

When rolling a material to be rolled such as a slab, it is generally known that wrinkles enter the surface and the back surface of the material to be rolled due to various factors. In particular, when rolling at both ends in the longitudinal direction of the material to be rolled, wrinkles resulting from the flow of the edge of the material to be rolled to the other end side (the opposite side from where the material to be rolled enters the rolling mill) are introduced. Sometimes.
Since the cutting process is performed on the part containing the wrinkles with a cutting machine, various techniques for reducing the cutting length (the length of the wrinkles) and improving the yield of the material to be rolled have been developed. (For example, Patent Document 1 and Patent Document 2).

In Patent Document 1, when a metal plate is manufactured through a width direction rolling step and a longitudinal direction rolling step, at least the tail end portion of the plate is rolled in all or part of the rolling passes in the width direction rolling step. In this case, the upper and lower material speeds of the entry-side material are made equal by giving the upper and lower roll peripheral speed difference.
In Patent Document 2, before the longitudinal rolling, the side surface shape corresponding to the front and rear end portions in the longitudinal rolling of the material to be rolled is formed into a tapered shape that is inclined to the surface side having a high heating temperature in the thickness direction of the material to be rolled. Edger rolling is performed.

In Patent Document 3, when rough rolling is performed by hot rolling of a slab, tentering rolling is performed from the first pass, and the tentering ratio (product width / slab width) is 1.3 or more. The tenter rolling is performed at a rolling reduction of 15% or less, and then the slab is turned 90 degrees to perform thickness rolling.
JP 2000-312904 A JP 2002-283021 A JP 2000-61591 A

  In Patent Document 1, although the amount of upper and lower surface wrinkles (front and back wrinkles) can be reduced by giving a difference in the peripheral speed of the upper and lower rolls, this technique is used when performing tentering (rolling for setting the width of the slab). It is a technique, and the rolling for adjusting the thickness is performed under different conditions. In addition, Patent Document 1 does not disclose in detail the relationship between the amount of penetration of the front and back rivets and the difference between the upper and lower roll peripheral speeds, and does not disclose the specific contents for performing the upper and lower roll peripheral speed differences. Therefore, even if the technique of Patent Document 1 is applied to a material that performs rolling on both ends in the longitudinal direction of the material to be rolled, it is actually impossible to sufficiently reduce the amount of wrinkles on the front and back surfaces. is there.

In Patent Document 2, it is possible to reduce wrinkles by performing edger rolling so that the side surface shape corresponding to the front and rear end portions is tapered, but in order to perform such rolling, edger rolling It is necessary to remodel the machine drastically and it is difficult to apply to actual operation.
Patent Document 3 is a technique for carrying out the rolling of the material to be rolled in the same manner as Patent Document 1, and even if it is applied to one that performs rolling on both ends in the longitudinal direction of the material to be rolled, The actual situation is that the amount of intrusion cannot be reduced sufficiently.
The present invention has been made in view of the above-described problem, and when rolling at both ends in the longitudinal direction of the material to be rolled, the difference in the amount of wrinkles between the surface side and the back surface side of the material to be rolled is made possible. An object of the present invention is to provide a hot rolling method for a material to be rolled that can be reduced in size.

In order to achieve the above object, the present invention takes the following technical means.
That is, when rolling at both ends in the longitudinal direction of the material to be rolled by a rolling mill having upper and lower rolling rolls, there is a difference in the amount of soot formed on the front and back surfaces of the material to be rolled when rolling. While performing the roll peripheral speed adjustment to adjust the peripheral speed difference between the upper and lower rolling rolls so as to be a predetermined value or less, the roll peripheral speed adjustment is 100 mm or more and 500 mm or less from the entrance side end of the material to be rolled. There is a point to do in the range.
The roll circumferential speed adjustment is preferably continued from the start of the circumferential speed adjustment to a rolling pass that satisfies the formula (1).

  The peripheral speed difference in the roll peripheral speed adjustment is preferably determined using at least one of a temperature difference between the front and back surfaces of the material to be rolled, a roll diameter difference between the upper and lower rolling rolls, and a pickup amount.

  ADVANTAGE OF THE INVENTION According to this invention, when rolling on the both ends side of the longitudinal direction of a to-be-rolled material, the penetration | invasion amount of the flaw on the surface side and back surface side of a to-be-rolled material can be suppressed as much as possible.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view of a thick plate rolling apparatus for rolling a material to be rolled (thick plate).
The thick plate rolling device 1 is for hot rolling the material 2 to be rolled, a heating furnace 3 for heating the material 2 to be rolled, and rough rolling for rough rolling the material 2 to be rolled heated by the heating furnace 3. And a finish rolling mill 5 that performs finish rolling on the material 2 to be rolled roughly by the rough rolling mill 4.
In the plate rolling apparatus 1, a heating furnace 3 is disposed on the most upstream side, and a rough rolling mill 4 and a finish rolling mill 5 are sequentially disposed from the upstream side to the downstream side. Hereinafter, for convenience of explanation, the rough rolling mill 4 and the finish rolling mill 5 may be collectively referred to as a rolling mill.

The rolling mill (rough rolling mill 4 or finish rolling mill 5) includes a pair of upper and lower work rolls (rolling rolls) 7U and 7D and a pair of backup rolls 8. The drive motor that rotationally drives the upper work roll (upper rolling roll) 7U and the drive motor that rotationally drives the lower work roll (lower rolling roll) 7D are configured separately, and the upper work roll 7U and the lower work roll 7D. And can be rotated individually. Hereinafter, for convenience of explanation, the upper work roll 7U and the lower work roll 7D may be collectively referred to as the upper and lower work rolls 7.
The hot rolling method for the material to be rolled according to the present invention will be described.

FIG. 2 is a flowchart of a rolling process for rolling the material to be rolled.
In the rolling process, the material 2 to be rolled heated to a predetermined temperature by the heating furnace 3 is taken out and conveyed to the roughing mill 4 (S1).
As shown in FIG. 3, first, the both ends of the longitudinal direction of the to-be-rolled material 2 conveyed by the rough rolling mill 4 are orient | assigned to the direction (orthogonal direction) orthogonal to a conveyance direction (rolling direction). And the to-be-rolled material 2 orient | assigned to the said orthogonal direction is introduce | transduced into the rough rolling mill 4, and, thereby, the width of the to-be-rolled material 2 is performed (S2: A widening process). The tentering step S2 is an operation for making the width of the material to be rolled 2 a predetermined size by introducing the material to be rolled 2 into the roughing mill 4.

After the width of the material to be rolled 2 is completed, the direction is changed so that both ends in the longitudinal direction of the material to be rolled 2 coincide with the rolling direction, and the material to be rolled 2 is introduced into the roughing mill 4 for rough rolling. (S3: Rough rolling process).
Now, in rough rolling, when rolling on both ends in the longitudinal direction of the material 2 to be rolled, the peripheral speed difference between the upper and lower work rolls 7 is adjusted.
Usually, the temperatures of the upper and lower surfaces of the material to be rolled 2 taken out from the heating furnace 3 are different. That is, the temperature distribution in the thickness direction of the material to be rolled 2 is different.

Therefore, when the material to be rolled 2 is introduced into the roughing mill 4 (when the material to be rolled 2 is caught in the upper work roll 7U and the lower work roll 7D), the front side (upper side) and the back side of the material 2 to be rolled ( The lower metal flow is different.
Here, considering the case where the peripheral speed of the upper work roll 7U and the peripheral speed of the lower work roll 7D are made constant, as shown in FIGS. 4 (a) and 4 (b), the thickness direction in the material 2 to be rolled. Due to the metal flow, the amount L1 of soot formed on the surface (upper surface) of the material 2 to be rolled differs from the amount L2 of soot formed on the back surface (lower surface). The amount of soot entering L1 is different from the amount of soot entering L2 when rough rolling is performed, so that the edge of the material 2 is on the other side (the side opposite to the material 2 entering the rolling mill). It can be attributed to the flow.

In addition, the amount L1 and L2 of wrinkles are wrinkles that enter the surface from one longitudinal end portion of the material 2 to be rolled 2 toward the other longitudinal end portion.
FIG. 5 shows a difference in peripheral speed between the peripheral speed of the upper work roll and the peripheral speed of the lower work roll (also called different peripheral speed, which is the peripheral speed of the lower work roll / the peripheral speed of the upper work roll) and the material to be rolled. 2 is a summary of the amount of soot entering the front surface (upper surface) and the amount of soot entering the back surface (bottom surface) based on operational results.
As shown in FIG. 5, the sum of the amount of wrinkles (front surface amount) L1 on the surface of the material 2 to be rolled and the amount of wrinkles (back surface amount) L2 on the back surface of the material 2 to be rolled 2 is substantially the same. is there. Here, when the difference between the surface flaw amount L1 and the back flaw amount L2 of the material to be rolled 2 is large, for example, cutting must be performed in accordance with the larger wrinkle (the longer one). Yield decreases.

  Therefore, according to the present invention, in order to prevent a reduction in the yield of the material 2 to be rolled, the amount of penetration of each wrinkle formed on the front and back surfaces of the material 2 (the surface amount L1, the back surface) The yield of the material 2 to be rolled is improved by adjusting the peripheral speed difference between the upper work roll 7U and the lower work roll 7D so that the difference in the amount L2) becomes as small as possible. Specifically, the portion with wrinkles is sheared by a cutting device after rolling, but the difference in the amount of penetration (front and back surfaces) depends on the cutting length measurement accuracy in this shear cutting and the cutting allowance on the front and back surfaces. Difference) is set to 15 mm or less, and the peripheral speed difference between the upper work roll 7U and the lower work roll 7D is adjusted.

Hereinafter, adjusting the peripheral speed difference between the upper work roll 7U and the lower work roll 7D so that the intrusion amounts L1 and L2 are the same may be referred to as roll peripheral speed adjustment.
The roll peripheral speed adjustment is performed in a range of 100 mm or more and 500 mm or less from the biting end with respect to the end on the side (biting side) where the material 2 enters the roughing mill 4. Specifically, the upper work roll 7U and the lower work roll 2U are introduced until the length of the material to be rolled 2 bitten into the roughing mill 4 reaches at least 100 mm after the material 2 is introduced into the roughing mill 4. A circumferential speed difference from the work roll 7D is provided.

  Further, if the length of the material to be rolled 2 bitten into the roughing mill 4 exceeds 500 mm after the material to be rolled 2 is introduced into the roughing mill 4, the circumference of the upper work roll 7U and the lower work roll 7D is increased. Finishing the speed difference. The reason for this will be described later. This roll peripheral speed adjustment is not only performed when one of the longitudinal directions of the material 2 to be rolled is introduced into the roughing mill 4, but the roll peripheral speed adjustment is performed in the same manner even when performing reverse rolling. I am going to do that. That is, also when the other longitudinal direction of the material 2 to be rolled is introduced into the roughing mill 4, the roll peripheral speed is adjusted within a range of 100 mm to 500 mm from the biting end.

  And this roll peripheral speed adjustment is continued from the start of the said peripheral speed adjustment to the rolling pass which satisfy | fills Formula (1). This roll peripheral speed adjustment is preferably performed after the width setting step if the width of the material to be rolled 2 is required. However, when the rolling of the material 2 to be rolled is not necessary (when the material 2 to be rolled out from the heating furnace 3 is roughly rolled as it is), the roll peripheral speed adjustment is started simultaneously with the start of the rough rolling.

And when the rough rolling of the material 2 to be rolled is completed, the material 2 to be rolled is transported to the finishing mill 5 and finish-rolled by the finishing mill (S4).
Table 1 summarizes the operation results of rolling the material to be rolled 2 with the difference between the peripheral speed of the upper work roll 7U and the peripheral speed of the lower work roll 7D.

Specifically, in this operation, a slab immediately after heating having a thickness of 275 to 280 mm, a width of 2000 to 2200 mm, and a length of 3700 to 4100 mm, a thickness of 15 to 17 mm, a width of 2500 to 2700 mm, and a length of 55000 Rolling was carried out to 60000 mm.
The vertical circumferential speed ratio in Table 1 corresponds to the above-described circumferential speed difference (different circumferential speed) (speed ratio when roll circumferential speed adjustment is performed), and the circumferential speed of the lower work roll / upper work roll The value of the peripheral speed. The roll peripheral speed adjustment range from the tip indicates the length when the roll peripheral speed is adjusted from the biting end (one end) to the other end. The front and back surface temperature difference is a difference between the surface temperature and the back surface temperature when the material to be rolled 2 is taken out from the heating furnace 3. The WR diameter difference is a difference between the diameter of the lower work roll 7D and the diameter of the upper work roll 7U. The pick-up amount is the difference between the table line (upper surface height of the transport roll that transports the material to be rolled 2) and the pass line (upper surface height of the lower work roll 7D).

In the operation of Table 1, the difference (front and back difference) between the amount of soot entering on the front side (front soot entering amount) and the amount of soot entering on the back side (back soot entering amount) is 15 mm or less, A good “◯” was given, and the others were “bad”.
The standard for the difference between the front and back surfaces (15 mm or less) is that, as described above, after rolling the material 2 to be rolled, the portion containing wrinkles is cut by a cutting device. Considering both of the long accuracy, it is sufficient to secure at least 15 mm, so that value is set.

In operation number 1 to operation number 5, the range of roll peripheral speed adjustment, the WR diameter difference, the pickup amount are made constant, and the front and back surface temperature difference is set in the range of 30 ° C to 45 ° C. It is the result of changing.
In operation number 1 to operation number 3, since the vertical peripheral speed ratio was too small, the amount L2 of the back surface increased, and the difference between the front and back surfaces exceeded 15 mm (Table 1, defect “x”).
In operation number 4, since the vertical circumferential speed ratio was 1.10, which was appropriate, the difference between the front and back surfaces could be 15 mm or less (Table 1, good “◯”).

In operation No. 5, since the vertical peripheral speed ratio was too large, the back surface penetration L2 was large, and the difference between the front and back surfaces exceeded 15 mm (Table 1, defective “x”).
Operation No. 6 and Operation No. 7 have the same range of roll peripheral speed adjustment, WR diameter difference, pickup amount as Operation No. 1 to Operation No. 5, and the temperature difference between the front and back surfaces is higher than that of Operation No. 1 to Operation No. 5. This is the result of changing the vertical peripheral speed ratio under low conditions.
In operation number 6, the vertical peripheral speed ratio is the same as that of operation number 4 (1.10). However, since the temperature difference between the front and back surfaces is small compared to operation number 4, the front penetration L1 is large. . As a result, the difference between the front and back surfaces exceeded 15 mm (Table 1, defective “x”).

Therefore, in operation number 7, the vertical peripheral speed ratio was reduced to 1.05. As a result, the amount of penetration L1 and L2 between the front surface and the back surface was substantially the same, and the difference between the front and back surfaces could be 15 mm or less (Table 1, good “◯”).
Operation number 8 and operation number 9 are the same as the operation number 1 to operation number 5 in the roll peripheral speed adjustment range, front and back surface temperature difference, and the pick-up amount, and the WR diameter difference is made lower than operation number 1 to operation number 5. This is a result of changing the vertical peripheral speed ratio under circumstances.
In operation number 8, the vertical peripheral speed ratio is the same as that of operation number 4 (1.10), but since the WR diameter difference is small from operation number 4, the amount L2 of penetration on the back surface is large. As a result, the difference between the front and back surfaces exceeded 15 mm (Table 1, defective “x”).

Therefore, in operation number 9, the vertical peripheral speed ratio was increased to 1.14. As a result, the amount of penetration L1 and L2 between the front surface and the back surface was substantially the same, and the difference between the front and back surfaces could be 15 mm or less (Table 1, good “◯”).
Operation number 10 and operation number 11 are the same as operation number 1 to operation number 5 in the range of roll peripheral speed adjustment, front and back surface temperature difference, and WR diameter difference, and the pickup amount is lower than operation number 1 to operation number 5. This is a result of changing the vertical peripheral speed ratio under circumstances.
In operation number 10, the vertical peripheral speed ratio is the same as that of operation number 4 (1.10). However, the operation amount 4 has a larger pickup amount and a larger back-entry amount L <b> 2. As a result, the difference between the front and back surfaces exceeded 15 mm (Table 1, defective “x”).

Therefore, in operation number 11, the vertical peripheral speed ratio was increased to 1.13. As a result, the amount of penetration L1 and L2 between the front surface and the back surface was substantially the same, and the difference between the front and back surfaces could be 15 mm or less (Table 1, good “◯”).
Operation number 12 to operation number 15 are the same as operation number 1 to operation number 5 in the front and back surface temperature difference, WR diameter difference, and pickup amount, and the roll peripheral speed adjustment range is changed compared to operation number 1 to operation number 5. It is a result.
In operation number 12, the roll peripheral speed adjustment range was less than 100 mm and very short (because adjustment was completed very quickly), so the difference between the front and back surfaces was very large, and the difference between the front and back surfaces exceeded 15 mm. (Table 1, bad “×”).

In operation number 13 to operation number 14, since the roll peripheral speed adjustment range was 100 mm or more and 500 mm or less, the amount of wrinkles L1 and L2 between the front surface and the back surface becomes substantially the same, and the difference between the front and back surfaces can be 15 mm or less. (Table 1, good “◯”).
On the other hand, as shown in the operation number 15, when the roll peripheral speed adjustment range is larger than 500 mm, the wrinkle penetration amounts L1 and L2 between the front surface and the back surface can be made substantially the same, but the upper work roll 7U or Since the load is applied to the drive motor that rotationally drives the lower work roll 7D for a long time, it is difficult to continue the operation. In other words, by setting the roll peripheral speed adjustment range to 100 mm or more, the difference between the front and back surfaces can be reduced to 15 mm or less. On the other hand, if the range becomes larger than 500 mm, the equipment limit (drive motor) The actual situation is that the operation becomes difficult due to the load limitation), and the range of the roll peripheral speed adjustment needs to be 500 mm or less.

  Table 2 shows the result of the roll peripheral speed adjustment continued from the start of the peripheral speed adjustment to the rolling pass satisfying the expression (1) in the rolling process in which the material to be rolled 2 was rolled, and the expression (1) It summarizes the results of rolling regardless of the relationship.

The circumferential speed differential rolling application pass shown in Table 2 shows the rolling pass from the start to the end of the roll circumferential speed adjustment.
Operation No. 16 was obtained by performing rough rolling after rolling out the material 2 to be rolled out from the heating furnace 3, and the roll peripheral speed was not adjusted at all. As a result, the difference between the front and back surfaces exceeded 15 mm (Table 2, defective “×”).
Operation number 17 to operation number 23 are the results of performing rough rolling while adjusting the roll peripheral speed immediately after the completion of the width setting of the material 2 to be rolled. Therefore, in operation number 17 to operation number 23, the thickness after the completion of the width setting is the thickness at the start of the roll peripheral speed adjustment.

In operation number 20 to operation number 23, since the roll peripheral speed adjustment was not continued until the expression (1) [t1 / t2 ≧ 1.5] was satisfied, the front and back surface difference exceeded 15 mm (Table 2, defective “×”).
On the other hand, in operation number 17 to operation number 19, since the roll peripheral speed adjustment was continued until the expression (1) [t1 / t2 ≧ 1.5] was satisfied, the difference between the front and back surfaces can be made 15 mm or less. (Table 2, good “◯”).
Operation number 24 to operation number 28 are the results of starting the roll peripheral speed adjustment from the middle of rough rolling (rolling). That is, operation number 24 to operation number 28 are results of performing rough rolling (rolling) several passes without adjusting the roll peripheral speed, and then performing rough rolling (rolling) while adjusting the roll peripheral speed. .

In addition, in the column of the circumferential speed differential rolling application pass of operation number 24 to operation number 28, the numerical value in parentheses indicates the range of the rolling pass in which the roll peripheral speed adjustment was performed in actual rolling [rolling start (rough The range of rolling passes where the roll peripheral speed was adjusted].
In the operation number 24 to the operation number 28, although satisfy | filling Formula (1) [t1 / t2> = 1.5], the roll peripheral speed adjustment is performed in the middle of rough rolling, in other words, after the completion of the tentering. Since it was desired to immediately adjust the roll peripheral speed, the difference between the front and back surfaces exceeded 15 mm (Table 2, defective “x”).

Therefore, by rolling so as to satisfy the formula (1) in the rolling after the completion of the tentering, the difference in the amount of penetration of the respective wrinkles formed on the front and back surfaces can be made a predetermined value or less. it can.
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
That is, in the above embodiment, it has been mainly explained that the roll peripheral speed adjustment is performed during rough rolling. However, the present invention is not limited to rough rolling, but can be applied to rolling performed after the completion of tentering. it can. In other words, the present invention can also be applied to rolling with no distinction between rough rolling and finish rolling.

  Further, the tentering step is not limited to the above embodiment. For example, after rolling the material 2 to be rolled in the longitudinal direction by the roughing mill 4, the material to be rolled 2 may be introduced into the roughing mill 4 in the orthogonal direction. In addition, when a predetermined width is obtained in the rough rolling process by performing rough rolling on the material to be rolled 2 conveyed from the heating furnace 3 to the roughing mill 4, the width of the material to be rolled 2 is increased. It is not necessary to perform.

It is the schematic of a thick plate rolling apparatus. It is a flowchart of the rolling process which rolls a to-be-rolled material. It is explanatory drawing of a tentering process and a rough rolling process. It is explanatory drawing of a wrinkle, Comprising: (a) The upper surface (front surface) is shown, (b) The lower surface (back surface) is shown. It is a related figure of the peripheral speed difference of an up-and-down work roll, and the penetration | invasion amount of the flaw of the front and back of a to-be-rolled material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thick plate rolling apparatus 2 Rolled material 3 Heating furnace 4 Rough rolling mill 5 Finishing rolling mill 6 Cooling apparatus 7 Upper and lower work rolls 7U Upper work roll 7D Lower work roll 8 Backup roll

Claims (3)

When performing rolling on both ends in the longitudinal direction of the material to be rolled by a rolling mill having upper and lower rolling rolls,
While performing the roll peripheral speed adjustment to adjust the peripheral speed difference between the upper and lower rolling rolls so that the difference in the amount of soot formed on the front and back surfaces of the material to be rolled when rolling is not more than a predetermined value, The roll peripheral speed adjustment is performed in a range of 100 mm or more and 500 mm or less from an end portion on the entry side of the material to be rolled. The said rolling peripheral speed adjustment is continued from the said peripheral speed adjustment to the rolling pass which satisfy | fills Formula (1), The hot rolling method of the to-be-rolled material of Claim 1 characterized by the above-mentioned.

  The circumferential speed difference in the roll circumferential speed adjustment is determined using at least one of a temperature difference between the front and back surfaces of the material to be rolled, a roll diameter difference between upper and lower rolling rolls, and a pickup amount. 2. A hot rolling method for a material to be rolled according to 2.

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