JPS6018492B2 - Tandem mill online roll polishing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an online roll polishing method for a hot tandem rolling mill.

In hot tandem rolling, especially in hot strip finish tandem rolling, the central surface portion (slope portion) of the work rolls that the rolled material passes through and comes into contact with during sheet passing wears out.
After roll dressing and before the next roll change, the board order is determined by wide board lots (one lot is generally 5
It is an assembly of six identical rolled materials.

) to successively narrower lots to minimize the effects of roll wear on the product shape (shapes such as plate crown, middle elongation, edge elongation, etc.).
In addition, in general, in a hot tandem rolling mill, a shape detector is installed on the exit side of the final stand to detect the shape of the rolled product, and an online shape detector is installed to measure the profile (plate crown) of the rolled product in the direction of the plate. A crown meter is installed and the crown meter measures the plate crown (plate crown waveform, plate crown amount) of the rolled product to obtain quality assurance data for the rolled product.

Work role changes are divided into regular changes and temporary changes between regular changes.

Periodic roll changes are defined by the total pressure extension due to roll surface roughness, and temporary roll changes are determined by the tandem mill shape control device (roll roll change) based on the shape detected by the shape detector during the regular roll change. If the shape cannot be corrected even if the pending device (pending device, etc.) is activated, or if an excessive high spot occurs in the waveform of the detected crown signal of the online crown meter, the crown amount of the detected crown signal may This is done when it is not possible to correct the plate crown amount to below the allowable value even if a roll pending device, etc. is activated. Incidentally, a spot is a locally thick part of a rolled product that is formed by the work roll due to unexpected foreign matter biting in the surface of the work roll, resulting in a crown. It is seen by the plate crown waveform of consignment rolled products on a meter. As mentioned above, when changing the threading order from wide to narrow strips, it is necessary to arrange the strips to be rolled in width order in advance, which poses a huge constraint on production efficiency in terms of linkage with previous and previous processes. It is a condition. In particular, when blooming rolled steel billets or continuously cast coin billets are sent directly to hot rolling equipment for rolling without being cooled, if you try to send them out in the order of strip width lots, steel making, blooming, continuous casting, etc. This method not only imposes severe constraints on the process, but also has the disadvantage of reducing the number of rolled materials that can be rolled before the next roll change. In order to solve the problems of the prior art, the present invention disposes an online roll polishing device in each stand of a hot tandem rolling mill, and each time a material to be rolled is rolled, it is formed into a work roll. By polishing the work rolls to eliminate the level difference between the threaded part and the non-threaded part of the material to be rolled, and by always maintaining the roll surface (profile) that is close to the one immediately after the roll change, the material must be rolled in the order of its width. In addition to removing constraints that had previously been required and increasing the degree of freedom in the rolling order,
This aims to improve work efficiency by increasing the number of rolled materials before the next roll change.

Conventionally, various methods and devices have been proposed for polishing work rolls while they are still installed in the rolling mill stand, but when and how to operate the polishing devices depends on the body of the work roll. A method has been proposed in which the profile in the longitudinal direction is measured with a roll profile meter, the polishing device is moved in the lengthwise direction of the work roll body, and the amount of polishing is changed in the lengthwise direction of the roll body to finish the work roll into the desired profile. .

In this method, it is necessary to detect the profile of the roll body in advance when polishing the roll breast, and it is difficult due to space constraints to install such a roll profile meter in each stand of a hot tandem rolling mill. However, it is difficult to manufacture a device that can detect profile changes on the order of microns. Therefore, in the present invention, each time the material to be rolled is rolled, the amount of wear on the work roll due to this rolling is predicted for each stand, and the non-rolling portion of the work roll during the rolling is calculated as follows:
Polish each stand by the amount of wear predicted above.

By this predictive polishing of the non-threaded part of the work roll, the level difference between the threaded part and the non-threaded part of the work roll of each stand is almost eliminated, and even when a medium-wide rolled material is rolled next. Significant deterioration of the shape of the rolled product is prevented. However, this polishing of the non-threaded portion is not based on the predicted amount of wear (because it is a predictive polishing, it is unclear whether the steps formed on the work rolls of each stand have been reliably eliminated). When the steps due to the above-mentioned prediction errors are accumulated and the steps become too large, if a medium-wide rolled material is then rolled, the rolled product will have an excessively stepped plate crown that is unacceptable in terms of quality. Therefore, in the present invention, the error level difference (polishing state of the non-threaded part of the previously rolled material) due to the predicted polishing after rolling of the previously rolled material is calculated using an online crown meter of the rolled product after rolling of the current medium-wide rolled material. Detected (estimated) from plate crown (especially plate crown waveform)
However, in order to eliminate the above-mentioned level difference in order to obtain a rolled product with a plate crown waveform that is acceptable in terms of quality, correction polishing of the work roll passing portion of the rolled material is performed this time.

Of course, at this time, predictive polishing is performed on the non-passing portion of the work roll of the material to be rolled this time. On the other hand, when rolling the same rolled material continuously or when the rolling process shifts from medium-wide to medium-narrow,
Naturally, the plate crown (plate crown amount) must be an amount that is acceptable in terms of quality.

Therefore, in the present invention, at the end of each rolling when the same rolled material is continuously rolled, and at the end of rolling when the rolled material changes from medium wide to medium narrow, the plate crown of each rolled product is measured by the online crown meter. (Especially the amount of plate crown)
In order to estimate the wear condition of the work roll threading section of each rolled material and obtain a rolled product with an acceptable plate crown amount in terms of quality, the threading section of the rolled material is This is for corrective polishing. In short, the present invention is capable of rolling a material to be rolled in a random order in a random order using a tandem mill equipped with an online crown meter on the exit side of the final stand, and for each stand to roll an arbitrary amount at an arbitrary position in the lengthwise direction of the upper and lower work rolls. Equipped with an online roll polishing device that performs polishing, predicts the level difference due to abrasion of the work roll threaded part during each rolling, and polishes the work roll non-threaded part to eliminate the level difference. A tandem mill characterized in that an abnormality in the plate crown is detected by the online crown meter, and based on the detection signal, the work roll shape is corrected by polishing the work roll slope portion and/or non-plate passing portion by a predetermined amount. This is an online roll polishing method.

In order to carry out the roll polishing method of the present invention, each stand of the tandem mill is equipped with an online roll polishing device that polishes arbitrary positions of the upper and lower work rolls in the longitudinal direction of the upper and lower work rolls by an arbitrary amount. For example, installing an online roll polishing device for each stand, which consists of a grindstone that is divided into multiple parts in the lengthwise direction of the upper and lower work rolls, and an actuator that presses each grindstone against the work roll surface, reduces the polishing time between rolling and rolling. This is preferable because it can be stored during idle time between. The method of the present invention will be explained in detail below.

First, we will discuss the plate crown signal obtained by the online crown meter.

FIG. 1 shows a standard plate crown waveform C of a rolled product obtained by an online crown meter at the exit of the final stand of a tandem mill, and h indicates the plate crown amount.

The plate crown amount h is determined as the maximum allowable crown amount in terms of the quality of the rolled product, and the crown waveform C also has an allowable waveform range.
A plate crown that deviates from the allowable waveform is called an abnormal plate crown. Next, a description will be given of predicted polishing of work rolls in each stand when the tandem mill has, for example, six stands.

Now, when a rolled product is produced from the rolled material of plate medium B using a 6-stand tandem mill, qualitatively M. The work roll Wi of the i rolling stand (i=1 to 6) is worn out.

That is, the plate passing portion (contact portion) of the rolled material is worn out. In FIG. 2, Gi is M. Indicates the amount of wear on the work rolls of the i-stand, AR and AL indicate the non-threaded parts (non-contact areas, non-wear parts) of the rolled material on both sides of the work roll Wi, and B indicates the amount of wear on the rolled material of the work roll Wi. It shows the passing part (contact part, wear part) of the plate, and corresponds to the inside of the plate of rolled material and rolled products. The above wear amount Gj varies depending on the steel type of the material to be rolled, the work roll material of each rolling stand, the work roll load, etc. Therefore, for example, the amount of wear Gj may vary depending on the past operating results (for example, the average wear amount per IHr is M.1, 2, 3 , 30,45 with 4, 5, 6 stands
It was 50.60,25,1&m/1 land.

), by determining the roll wear amount prediction formula based on factors such as the steel type of the rolled material, work roll material, roll load, etc. as shown in Equation '11, the roll wear amount each time one rolled material is rolled. can be predicted. Gi=F(C, Ri, Li)
......[11 However, Gi: Shame. Roll wear amount Ri of i-stand: 〃 Roll hardness Li:
〃 Roll load C: Steel type i of rolled material: Stand No. (i=1 to 6) Therefore, each time the material to be rolled is rolled, the non-threaded part of the material to be rolled of the work roll of each stand is removed from the above prediction formula, and the roll is polished by the amount of wear Gi calculated by Then, the stepped portion in the roll profile after rolling shown in FIG. 2 disappears.

By performing the above predictive polishing with sufficient precision, no matter what material is rolled next, no abnormal plate crown will occur in the plate crown (waveform, crown amount) of the rolled product, but in reality In this case, abnormal plate crown occurs due to insufficient accuracy of the roll wear amount prediction formula, occurrence of unpredictable situations such as foreign matter getting caught during rolling, etc.

This abnormal plate crown can be detected by the plate crown signal of the crown meter, and the types of this abnormal plate crown are as follows. [11 Abnormal plate crown of abnormal plate crown amount that occurs when transferring to the rolled material in the same plate or in the narrow plate '2}
Abnormal plate crown of plate crown waveform abnormality that occurs during transfer to wide medium rolled material [31 Abnormal plate crown of plate crown waveform abnormality (occurrence of high spots) due to foreign matter biting etc. Even when the roll pending device of the tandem mill (often installed on a stand in the latter stage) reaches its limit capacity, when the material is transferred to the material to be rolled in the middle, the plate crown obtained by the crown meter is still affected, as shown in Figure 3.
A crown amount exceeding the control limit (below the permissible limit) occurs.

In Fig. 3, h3 is the allowable crown amount limit, h2 is the control limit, h is the amount of returned crown that is desired to be restored by roll polishing, △b is outside the control limit, △h is the amount of deviation, B
The material to be rolled is being threaded. When such an abnormal crown is detected, in the present invention, the non-threaded portion of the rolled material in each of the work rolls described above is polished by a predicted wear amount Gi based on the prediction formula, and at the same time, the crown is removed. In order to restore the crown amount to the return crown amount, correct and polish the plate passing portions △Q and △wide of the rolled material on the work rolls other than △b, which are out of the control limit, and The amount of crown measured by a crown meter when the next rolled material is rolled is restored to the amount of returned crown.

The quality of the corrective polishing is determined by the plate crown of the next rolled product. The corrected polishing amount Oi (i=1 to 6) of Δb2 and Δ wide portion of the work roll of each of the above-mentioned rolling stands is calculated, for example, based on the following calculation formula.

Jj=h. X poison -----…----…- ■Part [2]
) Expression: The cause of abnormal crown amount is the wear of the work rolls on each stand of the tandem mill, and since the amount of wear on the rolls on each stand is different, it can be corrected by polishing the rolls. Even if the work rolls of each stand are uniformly polished by an amount corresponding to the desired crown amount h, the amount of crown of the next rolled material cannot be equal to the amount of return crown.

In other words, it is necessary to determine the polishing amount by considering the contribution rate of each stand to the plate crown, and in the present invention, the final stand, that is, M. Based on the work roll wear amount of 6 stands,
The ratio of the work roll wear amount Gi of each stand is considered as the crown contribution rate of each stand, and this contribution rate is multiplied by the crown amount h, which is to be recovered by roll polishing, to obtain the work roll polishing amount Ji of each stand. It has been decided. Next, to explain item (■), if the inside of the plate changes from narrow to wide, if the predicted roll polishing of the non-threaded part at the end of rolling of the previous narrow and medium material was insufficient in polishing amount, as shown in Figure 4. As shown in the figure, a stepped crown waveform is obtained on both sides. On the other hand, when the predicted polishing is overpolishing, a stepped crown waveform as shown in FIG. 5 is obtained. In other words, when the plate medium changes from narrow medium to wide medium, and the plate crown waveform of the plate crown signal from the crown mark of the first rolled product of wide medium material is as shown in Fig. 4 or 5, the wide medium material changes to wide medium material. It can be assumed that the polishing state of the upper and lower work rolls immediately before rolling was as shown in FIG. 6 or 7. Now, if the crown waveform as shown in Fig. 4 is obtained and the waveform step difference △h2 exceeds the control limit, the non-threaded parts AR and AL of the work roll of wide medium material are
At the same time, polish the predicted wear amount Gi based on the prediction formula, and at the same time polish the △Q, △ wide part of the crown waveform in the threading part B of the work roll of the wide medium material, and then polish the wide medium material of the same medium. Corrective polishing is performed so that the steps in the crown waveform disappear when rolled.

In other words, polishing is performed so that the step in the work roll profile estimated from the crown waveform disappears. In this case, the corrected polishing amount Ki (i=1 to 6) of the three parts ΔQ and Δb of the work roll of each rolling stand is calculated based on, for example, the following calculation formula. Ki=△h2×reed ……………[3
'The above operation is repeated for the second and subsequent pieces of the same wide medium material until the step in the crown waveform and the step in the estimated work roll profile disappear.

On the other hand, if a crown waveform as shown in Fig. 5 is obtained and the step difference Δh3 of the waveform exceeds the control limit, the non-threaded parts AR and AL of the wide medium material should be polished by the amount of wear Gi as described above. At the same time, the Δb portion of the inner crown waveform of the work roll passing slope part B of the wide medium material is corrected and polished so that the step difference in the crown waveform will disappear when the same wide medium material is manufactured next time.

In other words, corrective polishing is performed to eliminate the step in the work roll profile estimated from the crown waveform. In this case, the corrected polishing amount Li (i=1 to 6) of the Δq portion of the work roll of each rolling stand is calculated based on, for example, the following calculation formula. Li=△h3×poison ……A41 The above operation is repeated for the second and subsequent pieces of the same wide medium material until the step in the crown waveform and the step in the estimated work roll profile disappear.

Next, the {3}th term will be explained.

Now, as shown in Figure 8, a highly steep high spot P is detected by the crown meter, and if this high spot height △P exceeds the control limit, polishing is performed over the entire length of the work roll. . In this case, the threading part of the work roll of each stand for the material to be rolled is set at the height of the high spot △
P, the non-threaded part of the roll of each stand has the predicted wear amount Gj
Polish the amount by adding the spot height amount △P to /. That is, the respective polishing amounts Mi and Ni (i=1 to 6) of the non-passing portion and the passing portion of the work roll of each stand are as follows. Non-threaded part: Mi=△P Slope part: M=G+△Pro. ．． ．． ．．
．． ．． ．． ．． ．． ■This prevents the occurrence of high spots on the plate crown of the next rolled material.

As described above, the present invention basically predicts the level difference between the work roll passing part and the non-rolling part due to roll wear every time the material to be rolled is rolled, and performs a process to eliminate this level difference. −
In addition to polishing the non-rolled parts, in order to always ensure that the rolled product has a plate crown that is acceptable in terms of quality, if any abnormality is found in the plate crown of the rolled product obtained from the crown machining outside after each rolling, the The plate part will also be polished and corrected.

FIG. 9 shows the overall configuration of an embodiment of an online polishing apparatus that implements the method of the present invention.

M indicates a 6-stand tandem mill, la, 2a
, 3a, 4a, 5a, 6a and lb, 2b, 3b, 4b
, 5b, 6b are M. These are the upper work roll and lower work roll of the 1st, 2nd, 3rd, 4th, 5th, and 6th rolling stands. 7 is a roll polisher for upper work rolls la, 2a, 3a, 4a, 5a, 6a, and 8 is a roll polisher for lower work rolls lb, 2b, 3b.
, 4b, 5b, and 6b roll polishers.

FIG. 10 is a side view of the roll polishers 7, 8, 30, 3
Reference numeral 1 denotes a top stripper and a bottom stripper which are provided at the exit of each stand close to the upper and lower work rolls a and b.

Reference numerals 32 and 33 denote grindstones for polishing the work rolls a and b. These grindstones 32 and 33 are held by retainers 34 and 35 that can slide freely over the strippers 30 and 31, and are attached to an operation cylinder 36.
, 37, the grindstones 32, 33 are rolled a
, so that it is pressed against the b side.

FIG. 11 is a simplified diagram of the planar state of FIG. 10, in which the grinding wheels 32 are arranged in multiple sections in the lengthwise direction of the body of the work roll a, and are equipped with operation cylinders that press each grinding stone against the roll surface. .

In the drawing, 32a is a grindstone for polishing the central part of the roll body length, and 32b is a grindstone placed on both outer sides of the grindstone 32a. 32c, 32d, 32e, 32f, 32g, 32h
is a whetstone, and these whetstones 32c, 32d, 32e, 32
f, 32g, 32h are whetstones 32b, 32c, 32d, 3
2e, 32f, and 32g, respectively.

FIG. 12 shows the above-mentioned grindstones 32a to 32h.

The figure shows the state seen from the roll surface, and the parts other than the grindstones at both ends of the roll body are shaped like parallelograms to prevent polishing residue. In Fig. 11, 36a to 36h are the grindstones 32a.
~32h operating cylinder. 38a to 38h are hydraulic or pneumatic piping systems for driving the cylinders 36a to 36h, and each system is connected to a hydraulic or pneumatic source 39.

40a to 40h are ON- placed in systems 38a to 38h.
This is an OFF solenoid valve, and when this valve is turned ON, the operating cylinder connected to this system operates to press the grindstone against the roll surface.

41a to 41h are switches for turning ON/OFF solenoid valves ON/OFF.

Since the switches 41a to 41h are configured as described above,
By selectively turning on . It is possible to polish any position in the lengthwise direction of the work roll. For example, the polishing degree when the switches 41a to 41h are turned on is as follows. switch 4 1a
60 enemy switch 4 1 a
,4 1 b 80 enemy switch 4
1 a~4 1 c loo enemy switch 4 1 a~4 1 d 12
0 enemy switch 4 1 a~4 1 e
140 enemy switch 4 1 a ~ 4 1 f
160 port switch 4 1 a~4 1
g 180 port switch 4 1 a~
4 1 h 200 Cape Nao No. 11,
Although FIG. 12 shows the configuration of the roll polisher 7 for the upper work roll, the roll polisher 8 for the lower work roll is also configured in the same manner.

FIG. 13 is a chart showing the relationship between the contact time between the roll and the grindstone and the amount of roll polishing when the roll polishers 7 and 8 are used. F2, F,, F5, F6
is No. 4, 3, 2, 1, 5, 6 stand work rolls are pressed against the grindstone with a pressing force of 2.0, 1. &1.3,1.
This shows the case of pressing at 0, 0.8, 0.5 (of k9).

As is clear from FIG. 13, the amount of roll polishing can be adjusted by adjusting the contact time and pressing force.
Now, assume that the pressing force is the same for each stand, and only the contact time is adjusted to adjust the amount of roll polishing. In FIG. 9, 9 is M. This crown meter 9 is an online crown meter of steel strip 10 placed at the exit of stand 6.
Movable thickness gauge 1 1, fixed thickness gauge 12 and double thickness gauge 1
It consists of a crown calculator 13 that processes the detection signals No. 1 and 12 to calculate a plate crown waveform and a plate crown amount.

14 is a monitor that displays the plate crown waveform.

Reference numeral 15 denotes an intermediate meter for measuring the inside of the bar placed on the entrance side of the tandem mill.

No. 16 calculates the predicted polishing position in the longitudinal direction of the work roll from the bar signal from the intermediate plan 15, and calculates the predicted polishing position from this in the direction of the length of the work roll body.
Determine the grindstone that should be applied to the work roll in common for stands 1 to 6, and calculate the amount of roll wear Gi for each stand based on the mth formula, and determine this amount of wear Gi as the amount of polishing, Based on the descriptive formula that describes the relationship between the contact time between the roll and the grindstone and the amount of polishing of the roll as shown in FIG. This is a predictive polishing calculator that determines the pressing time of the grindstone located in the non-rolling part of the rolled material of the work rolls of stands 1 to 6 for each stand.

17 is based on the plate crown signal from the arithmetic unit 13,
The type of abnormal plate crown is determined by using the method, and if the determined abnormal plate crown is abnormal beyond the control limit, the body length of the work roll is determined from the bar signal from the intermediate plan 15 and the crown signal from the calculator 13. Calculate the correction polishing position in the direction and remove the mosquito for correction polishing. 1 ~ Shame. Determine the grindstone that should be pressed against the work roll for all 6 stands, and perform corrective polishing for each stand using any of formulas '2' to '51, depending on the type of abnormal plate crown determined. This is a correction polishing calculator that calculates the pressing time of the grindstone based on the descriptive formula of the roll grindstone contact time and the polishing amount.

18 is the predicted polishing calculator 16 and the corrected polishing calculator 17.
Shame for the predicted polish given. The position of the grindstone in the lengthwise direction of the work roll body that is operated in common for stands 1 to 6, and Pressing time for each stand from 1 to 6, and M. for corrective polishing. The position of the grindstone in the lengthwise direction of the work roll that is operated in common for stands 1 to 6, and the This is a control device that controls the groups of roll polishers 7 and 8 according to the pressing time of each of the 1st to 6th stands.

Next, the operation of the tandem mill online polishing apparatus shown in FIGS. 9, 10, 11, and 12 will be described.

Now, assume that a medium B rolled material as shown in FIG. 11 is rolled by a tandem mill, and the online crown meter 9 detects a plate crown with a normal crown amount and crown waveform as shown in FIG. In this case, the corrective polishing calculator 17 does not output, and the predictive polishing calculator 16
shame. Wear amount Gi of work rolls of stands 1 to 6 (i=
1 to 6) are calculated. Next, the above wear amount Gi (i=1 to 6
) to relatively zero, this wear amount Gi (i=1
~6), M. It is determined as the polishing amount Gi of the non-threaded portion of the work rolls of stands 1 to 6. Next, the middle plate B of the rolled material,
Karachi. Since you can see the threaded parts of the work rolls of stands 1 to 6, you can also see the non-threaded parts, and from now on M. Determine the grindstone that should be pressed against the work roll in common for stands 1 to 6. For example, in the case of FIG. 11, it is decided to operate the grindstones 32d to 32h. Next, the ship. Amount of polishing Gi (i = 1 to 6) of the non-threaded part of work rolls of stands 1 to 6
Based on the correlation between roll-grindstone contact time and roll grinding amount, M. Pressing time Ti of grindstones 32d to 32h located in non-threading parts of work rolls of stands 1 to 6
(i=1 to 6) is determined for each stand. The above M.
The position of the grindstone that is operated in common for stands 1 to 6, and the position of the grindstone.
The control device given the pressing time Ti for each stand from 1 to 6 is 18. ON-OFF solenoid valves 40d to 4 for pressure systems of polishers 7 and 8 for upper and lower work rolls in stands 1 to 6
0h is turned on in common to all stands, and the above-mentioned pressing time Ti (i=1 to 6) is maintained for each stand.

As a result, No. The roll wear amount Ci (i=1 to 6) of the work rolls of the 1st to 6th stands is relatively zero. Therefore, even if next, a rolled material of medium B or wider than medium B is rolled in a tandem mill, a rolled product acceptable in terms of quality can be obtained.

Now, suppose that a plurality of sheets of the plate B are rolled, the predicted polishing is performed, a Hironaka Nakazato rolled sheet as shown in FIG. 11 is rolled with a tandem mill, and an online crown meter 9 is used. For example, suppose that a stepped plate crown as shown in FIG. 4 has been detected, and the step difference Δh2 exceeds the control limit, which is set to be 4 mm smaller than the allowable limit. It is considered that the step difference Δh2 is caused by a gradual error in predicting the roll wear amount after the rolling of the medium B rolled material. In this case, the corrective polishing calculator 17 estimates the roll profile as shown in FIG. 6, and determines the portions Δb2 and Δ of the threaded portion of the material to be rolled as the corrective polishing position.

Now it's a snake. Determine the grindstone that should be pressed against the threading section of the work roll in common for stands 1 to 6. For example, in the case of FIG. 11, it is decided to operate the grindstones 32d, 32e, and 32f. Next, the corrected polishing amount Ki (i=1 to 6) of AQ and Δ wide part of the threading part of the rolled material for each stand is determined using the {11, '31 equation. Next, M. 1-6
The grindstone 3 located in the work roll passing section of the stand
The pressing circumstances mr (i=1 to 6) of 2d, 32e, and 32f are determined for each stand. On the other hand, the predictive polishing calculator 16
is based on formula '1}, and M. Amount of polishing Gi (i=
1 to 6).

Also, determine the grindstones to be pressed against the work roll located in the non-threading part from B2 in the board.For example, in the case of Fig. 11, it is decided to operate the grindstones 32g and 32h. Pressing time Ti (i=1
-6) are determined for each stand. The above-mentioned corrective polishing calculator 17 gives the position of the whetstone to be activated in common to each stand and the pressing force i' for each stand, while the predicted polishing calculator 16 gives the position of the whetstone to be activated in common to each stand, The control device 18 is given a pressing time Ti for each stand. ON-OFF solenoid valves 40d, 4 for pressure systems of work roll polishers 7, 8 of stands 1 to 6
Turn on 0e, 40f, 40g, and 40h for all stands, and turn on valves 40d, 40e, and 40 for each stand.
f is the pressing time Ti', and the valves 40g and 40M are held for the time Ti.

As a result, even if a medium-sized rolled material is then rolled in a tandem mill, a rolled product that is acceptable in terms of quality can be obtained. For example, when an abnormal crown as shown in FIG. 3, FIG. 5, or FIG. 18. As detailed above, in order to enable medium free rolling, the online roll polishing method of the present invention removes the step of the work roll due to roll wear every time the material to be rolled is rolled. In addition to predictive polishing of non-threaded parts of the material, in order to always obtain a rolled product with an acceptable quality in terms of quality even during medium free rolling, the plate crown of the rolled product is obtained using an online crown meter after each rolling process. Correct polishing is also performed on the threaded portion of the work roll of the rolled material in accordance with the signal.

Therefore, according to the method of the present invention, a rolled product with a plate crown that is acceptable in terms of quality can always be obtained by medium free rolling, and therefore has extremely high industrial value. Moreover, according to the present invention, ■
In tandem rolling, which required rolling in the middle order, material setup efficiency is improved because restrictions on the rolling order during sheet passing are relaxed. ■Since the period between roll changes and roll changes can be lengthened, rolling efficiency can be improved and the number of rolls polished can be reduced. ■Using the existing crown meter to estimate roll brofil without adopting a special roll brofil meter,
Since the rolls are polished, equipment costs can be reduced. ■On a regular basis, the non-threaded part of the rolled material is roll-polished, and only when an abnormal crown is detected, where the plate crown exceeds a predetermined control limit, the threaded part of the rolled material is polished. Since roll polishing is used, it is possible to prevent an increase in the roll consumption rate compared to a roll polishing method in which the roll length is the same throughout the entire period.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the plate crown signal of the rolled product by the online crown meter installed at the exit of the final stand of the tandem mill, Fig. 2 is an explanatory diagram of the wear status of the work rolls of the tandem mill due to rolling, and Fig. 3 Figures 4, 5, and 8 are explanatory diagrams of the abnormal plate crown, Figures 6 and 7 are estimated views of the profile of the work roll before rolling of the rolled product of the plate crown in Figures 4 and 5, and Figure 9 is an illustration of the profile of the work roll before rolling of the rolled product of the plate crown in Figures 4 and 5. 10 is an explanatory diagram of the overall configuration of an embodiment of an online roll polishing apparatus for carrying out the method;
, 11 and 12 are detailed explanatory diagrams of the roll polisher shown in FIG. 9, and FIG. 13 is a chart showing the relationship between the contact time between the roll and the grindstone of the roll polisher versus the amount of roll polishing. la~6a...Snake. 1~No. 6 Upper work roll of rolling stand, lb~6b...M. 1~M. 6 Lower work roll of rolling stand, 7... Roll polisher for upper work roll, 8... Roll polisher for lower work roll, 9... Online crown meter, 10
．． ．． ... Steel strip, 11 ... Mobile thickness gauge, 1
2...Fixed thickness gauge, 13...Crown calculator, 14...Monitor, 15...Medium plan, 16...Predictive polishing calculation Vessel, 17...
・Correction polishing calculator, 18...Control device, 30...
...Top stripper, 31...Bottom stripper,
32, 33...Whetstone, 34,35...
Retainer, 36, 37... Operation shilling, 38.
...Piping, 39...Pressure source, 40...
・ON-OFF solenoid valve, 41...switch. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 13 Figure 10 Figure 11 Figure 12

Claims (1)

[Claims] 1. An online roll that grinds an arbitrary amount at an arbitrary position in the lengthwise direction of the upper and lower work rolls for each stand when rolling the material to be rolled in a random order in terms of width using a tandem mill with an online crown meter placed on the exit side of the final stand. A polishing device is installed, and for each rolling, the amount of level difference due to wear of the threaded part of the work roll is predicted, and the non-threaded part of the work roll is polished to eliminate the level difference. Online roll polishing for a tandem mill characterized by detecting an abnormality in the plate crown, and correcting the shape of the work roll by polishing the work roll passing portion and/or non-passing portion by a predetermined amount based on the detection signal. Method.