JP3772464B2 - Grinding method of rolling roll surface - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a grinding method for the surface of a rolling roll, and more particularly to a grinding method for a surface of a rolling roll that can reduce the amount of grinding in an offline roll shop and improve the roll basic unit.
[0002]
[Prior art]
When a steel slab is hot-rolled by a rolling mill, a fatigue layer is gradually generated on the roll surface that comes into contact with the material to be rolled of the rolling roll. This fatigue layer increases in depth (thickness) from the roll surface as the rolling load (generally expressed by the rolling amount, rolling distance, or the product of both) increases. FIG. 2 shows an example of the relationship between the fatigue layer depth and the rolling load (using the rolling distance), both of which are proportional.
[0003]
When such a fatigue layer progresses, the roll surface breaks down due to cracks formed in the fatigue layer, and if left untreated, the life of the rolling roll is shortened. Further, if rolling is performed with the roll surface rough due to the cracks, as a result of being transferred to the material to be rolled, a rolled product is damaged, and it is difficult to always ensure stable product quality. Therefore, as a countermeasure, conventionally, the rolled roll is removed from the rolling mill and taken off-line to a roll shop, and the thickness of the fatigue layer required based on the rolling load of the rolling roll is determined by a roll grinder. Is removed by grinding. The rolling roll from which the fatigue layer has been removed is incorporated into a rolling mill and used again.
[0004]
On the other hand, apart from the formation of the fatigue layer, mechanical wear occurs in a portion of the rolling roll that comes into contact with the material to be rolled. This wear also proceeds with rolling, and a step (wear step) is formed between the non-wear portion that does not come into contact with the material to be rolled, and the roll profile changes. The range in which this wear level difference occurs is the range of the plate width of the material to be rolled. Therefore, in an actual rolling operation, the sheet width range of the material to be rolled is, for example, 800 to 1500 mm, which ranges from a narrow width to a wide width. Therefore, the range of wear also varies depending on the sheet width of the material to be rolled. For example, when rolling a wide material using a rolling roll that has been rolled to produce a wear step in the sheet width range, a narrow worn portion and a non-wear portion on the outer side are already generated. A roll profile including a step is transferred to a wide product and a good product cannot be obtained. Therefore, in order to prevent as much as possible the influence of the wear step caused by rolling of a certain sheet width material on the next rolling with different sheet widths, when rolling a plurality of types of sheet width materials, the rolling order is as wide as possible. The operation is regulated so that it becomes a narrow material. However, even if the rolling order is regulated, the wear step will progress, so it will eventually reach the limit. If the limit is exceeded, the rolling roll is removed from the rolling mill and roll grinding is performed with a roll grinder in an off-line roll shop to correct the deformation of the roll profile due to a wear step, as in the case of removing the fatigue layer.
[0005]
However, in recent years, in consideration of such rolling order restrictions hindering the improvement of productivity, online roll grinding technology in which a roll grinding device (roll grinder) is arranged in the rolling mill has been put into practical use, and online roll grinding has been performed. It has come to be.
[0006]
In online roll grinding, the following two types of grinding are mainly performed.
(1) Partial grinding in which the wear step is eliminated by grinding the outside of the through plate portion.
(2) Whole surface grinding to remove uneven wrinkles locally generated on the roll surface by grinding the entire roll surface.
[0007]
With the practical application of this online roll grinding technology, the rolling order regulation for the rolled material sheet width described above can be relaxed and the surface flaws of the rolled material due to the irregularities can be prevented. Improvement and improvement in the quality of the hot-rolled steel sheet to be manufactured can be expected.
[0008]
[Problems to be solved by the invention]
In the case of the conventional roll surface grinding method using an on-line roll grinder, the purpose is to remove the roll roll wear level (partial grinding) and smooth the roll surface (full surface grinding) while rolling. There is to fix. Of course, the fatigue layer on the surface of the rolling roll is also removed to some extent during the roll surface grinding by the on-line roll grinder, but the amount of fatigue layer removal is not controlled and is unknown.
[0009]
After all, the fatigue layer formation rate during rolling is larger than the fatigue layer that is removed by online full surface grinding to remove local irregularities and defects. Since it cannot be completely removed, even if rolling is performed while online whole surface grinding is repeated, accumulation of a fatigue layer proceeds during that time. Therefore, in the conventional grinding method of the surface of the rolling roll, regardless of whether or not the online roll grinder is used, when the rolling load of the rolling roll reaches a predetermined reference amount, the rolling roll is extracted from the rolling mill, The fatigue layer is completely ground and removed by a shop grinding device.
[0010]
However, when grinding in a roll shop, the fatigue layer removed by the online roll grinder is not taken into account, and the amount of roll grinding is based on the estimated depth of the fatigue layer that is determined exclusively according to the rolling load. Therefore, in the case of an operation mode using an on-line roll grinder, there is a problem that excessive grinding is performed at a roll shop, resulting in deterioration of the roll basic unit.
[0011]
The present invention has been made to solve such a conventional problem, and prevents excessive grinding by effectively combining grinding by an on-line roll grinder and grinding by a roll shop, and thus, a roll basic unit. It aims at providing the grinding method of the surface of a rolling roll by the on-line roll grinder which can improve.
[0012]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the rolling roll surface grinding method according to the present invention comprises rolling while performing roll grinding with an on-line roll grinder, and then grinding the surface of the rolling roll extracted from the rolling mill with an offline grinder. In doing so, the relationship between the rolling load and the depth of the rolling roll fatigue layer formed according to the rolling load is determined empirically in advance, and the roll shop grinding is predicted by predicting the depth of the rolling roll fatigue layer. It is set in the apparatus, the roll grinding amount ground by the on-line roll grinder during rolling with the rolling roll is memorized, and the rolling based on the grinding amount and the predicted depth of the rolling roll fatigue layer Determining the residual fatigue layer depth of the roll and performing roll grinding with the offline grinder with a grinding amount equal to the residual fatigue layer depth A.
[0013]
According to the present invention, at the roll shop, the grinding amount corresponding to the residual fatigue layer depth obtained by subtracting the total of the actual grinding amount by the online roll grinder from the depth of the rolling roll fatigue layer predicted according to the rolling load. Since grinding is performed, excessive grinding at the roll shop can be prevented, and the roll basic unit is improved.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory view showing an outline of an embodiment of an online roll grinding apparatus (online roll grinder) according to the present invention.
[0015]
First, the apparatus configuration of the online roll grinder 20 will be described. In FIG. 1, a grinding wheel 2 for grinding a surface of a rolling roll (work roll) 1 of a rolling mill is rotatable to a bearing box 5 via a bearing 3. It is supported. A grinding wheel rotation motor 7 supported on a bearing box 6 via a bearing 4 is disposed coaxially with the grinding wheel 2. The drive shaft 9 of the grinding wheel and the output shaft 10 of the grinding wheel rotation motor are rotatably connected by a universal joint 8 with a spline. The bearing box 5 on the grinding wheel 2 side is attached to the mount 13 via a linear guide ll, and moves forward and backward in the axial direction while being guided by the linear guide ll by the operation of the pressing cylinder 12. The grinding wheel 2 is pressed against the rolling roll 1 by the forward movement. And the mount 13 of the pressing cylinder 12 is movable along the axial direction of the rolling roll 1.
[0016]
The operation of the pressing cylinder 12 and the grindstone rotating motor 7 is controlled by a command from a drive control device (not shown). The drive control device performs grinding for a predetermined grinding amount in accordance with a model formula for an actual grinding amount, which is obtained in advance with the pressing force, the number of roll rotations, and the feed amount of the grinding wheel in the rolling roll axis direction as variables. Thus, the pressing force and the feed amount are controlled. The drive control device stores the grinding amount in a memory when grinding is performed.
[0017]
Next, a method of grinding the surface of the rolling roll by a combination of the online roll grinder 20 of FIG.
First, for each material to be rolled with different rolling conditions, the relationship between, for example, the rolling distance (km) as the rolling load and the depth of the fatigue layer formed on the surface of the rolling roll 1 under the rolling conditions is determined empirically. (See FIG. 2) From now on, the depth A of the rolling roll fatigue layer when the material to be rolled is rolled for a predetermined distance is predicted and set in the grinding apparatus of the roll shop. As the rolling load, for example, the rolling amount (the number of coils or the weight) or the rolling amount × the rolling distance may be employed.
[0018]
On the other hand, in a plurality of full surface grindings by the online roll grinder 20 repeatedly performed during the rolling, the actual online grinding amount for each time until the end of the rolling cycle is stored in the memory of the drive control device.
[0019]
That is, online rolling for a predetermined time by the online roll grinder 20 is performed a plurality of times until the rolling distance from the predetermined rolling roll reaches a preset one rolling cycle after the rolling is started. At that time, the drive control device (not shown) instructs the drive device of the gantry 13 to move the gantry 13 of the online roll grinder 20, and the grinding wheel 2 moves from the standby position toward the surface of the rolling roll 1. When the grinding wheel 2 reaches a predetermined position set in advance, the grinding wheel rotation motor 7 is driven and the grinding wheel 2 starts to rotate. Subsequently, the grinding wheel 2 is pressed against the surface of the rolling roll 1 by the operation of the pressing cylinder 12, and the entire grinding of the surface of the rolling roll 1 by the grinding wheel 2 starts.
[0020]
The grinding wheel 2 performs grinding while moving from one end side to the other end side of the rolling roll 1 along with the movement of the gantry 13, and when a predetermined amount of grinding is completed, the actual grinding amount is stored in the memory of the drive control device. Thereafter, the pressing cylinder 12 operates in the backward direction, the grinding wheel 2 moves backward, and the grinding wheel 2 moves to the standby position together with the gantry 13 to prepare for the next grinding.
[0021]
Thus, when removing the local unevenness | corrugation flaw of the rolling roll 1 by the online roll grinder 20, the fatigue layer formed at the time of rolling on the roll surface is also ground, but the fatigue formed on the rolling roll 1 at the time of rolling. Since not all the layers are removed, the residual fatigue layer gradually accumulates as the rolling distance increases. Therefore, after one rolling cycle is completed after a predetermined number of online grindings, the rolling roll 1 is extracted from the rolling mill and taken out to a roll shop, and the residual fatigue layer is ground by a roll grinding apparatus. Specifically, from the predicted depth A of the rolling roll fatigue layer set in the grinding machine of the roll shop first, the online grinding amount of each time by the online roll grinder 20 stored in the memory of the drive control device. The roll shop is ground by an amount corresponding to a value C (C = A−B) obtained by subtracting the total amount B.
[0022]
FIG. 3 shows a comparison of the difference in grinding amount in one rolling cycle between the method of the present invention and the conventional method. A in the figure represents the depth of the rolling roll fatigue layer formed during one rolling cycle regardless of the use / non-use of the online roll grinder, and is also the conventional roll shop grinding amount. B in the figure represents the total amount of grinding of the plurality of times of grinding by the online roll grinder performed during the rolling cycle, and is the total depth of the rolling roll fatigue layer ground by the online roll grinder. C in the figure represents the roll shop grinding amount (that is, the depth of the residual fatigue layer) in the method of the present invention. As apparent from this figure, according to the grinding method of the present invention, the roll shop grinding amount (C) is reduced by the amount of the online roll grinder grinding amount (B) from the conventional roll shop grinding amount (A). Therefore, the basic unit of roll is improved accordingly.
[0023]
In the embodiment of the present invention described above, the grinding amount control by the on-line roll grinder is based on a model formula including the pressing force, the roll rotation number, and the feed amount of the grinding wheel in the roll axis direction as variables. However, the control of the grinding amount in the present invention is not limited to this. For example, the amount of movement of the grinding wheel 2 in the pressing direction by the pressing cylinder 12 is used using a linear position sensor such as a linear encoder. Thus, the grinding amount can be controlled with high accuracy.
[0024]
In addition, when an online roll profile meter capable of measuring the roll profile online is installed in the rolling mill, the amount of online roll grinding based on the data measured by the online roll profile meter before and after performing online roll grinding. Can be obtained accurately.
(Example)
Below, the result of the experiment implemented using the actual hot rolling line is shown as a specific example.
[0025]
The rolling mill used was a hot strip mill equipped with a group of 7 finishing mills, and the rolling distance of the material to be rolled was set based on the final stand. The number of rolling cycles was 100 coils, and the rolling distance was 120 km as one cycle. During the one rolling cycle, grinding with 1.5 μm was performed 20 times with the online roll grinder 20 installed in the finishing mill. That is, the total amount of online grinding is (1.5 μm / time) × 20 times = 30 μm. As for the depth of the fatigue layer formed on the rolling roll by the one-cycle rolling, the value obtained from the linear relationship in FIG. 2 is 50 μm.
[0026]
In the conventional method, after the end of one rolling cycle, the rolling roll 1 was extracted and carried to a roll shop, and the grinding amount of the grinding device was set to 50 μm corresponding to the fatigue layer depth and ground. On the other hand, in the method of the present invention, the same material to be rolled is rolled for one cycle under the same rolling conditions, and then ground by a value of 20 μm obtained by subtracting the online total grinding amount of 30 μm from the fatigue layer depth of 50 μm by a roll shop grinding apparatus. The fatigue layer was completely removed.
[0027]
In the conventional method, when a total of 30 μm of online grinding amount is added, the total grinding amount becomes 80 μm, resulting in excessive grinding of 30 μm. In contrast, in the case of the method of the present invention, the total grinding amount of the online grinding amount and the offline grinding amount is 50 μm, and the fatigue layer can be completely removed with a grinding amount that is 30 μm less than the conventional method. Improved.
[0028]
【The invention's effect】
As described above, according to the present invention, the fatigue layer formed on the surface of the rolling roll by rolling is ground by a combination of an on-line roll grinder and a roll grinder in a roll shop. It can be removed completely without grinding, and as a result, the basic unit of the rolling roll can be improved.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an outline of an embodiment of an online roll grinding apparatus (online roll grinder) according to the present invention.
FIG. 2 is a diagram showing the relationship between the depth of a fatigue layer formed on a rolling roll and the rolling load.
FIG. 3 is a diagram showing a comparison between the rolling roll grinding amount of the method of the present invention and that of the conventional method.
[Explanation of symbols]
1 Roll 2 Grinding wheel 20 Online roll grinder

Claims (1)

After rolling while performing roll grinding with an online roll grinder, when grinding the surface of the rolling roll extracted from the rolling mill with an offline grinder, the rolling load and the rolling roll fatigue layer formed according to the rolling load A roll that has been empirically determined in advance with the relationship between the depth, the depth of the rolling roll fatigue layer is predicted and set in a grinding machine of a roll shop, and is ground by an online roll grinder during rolling with the rolling roll. The grinding amount is memorized, the residual fatigue layer depth of the rolling roll is obtained based on the grinding amount and the predicted depth of the rolling roll fatigue layer , and the grinding amount corresponding to the residual fatigue layer depth is obtained. A method of grinding a roll surface, wherein roll grinding is performed by the offline grinder.

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