JP2003053410A - Method for preventing meandering in skin pass mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of effectively preventing a strip from meandering in a skin pass mill hardly using high-class control equipment. SOLUTION: After a preceding material is passed (S6), before starting (S23) the rolling of the next material, rolls are screwed down at the set rolling load for the next material by right and left screw-down means and zero adjustment (SZ) in which the stroke of each of the screw-down means at that time is respectively determined as the reference point is performed. When the next material is rolled (S20, S23), the set rolling load is loaded on the next material by screwing rolls down so that there is no difference in the change of the stroke to the reference point between the right and left screw-down means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention described in the claims is a skin pass mill (temper rolling mill) used to enhance flatness and surface quality of a sheet, and is rolled (skin pass rolling).
It relates to a method for preventing the inner plate from meandering.

[0002]

2. Description of the Related Art A skin pass mill has a rolling reduction of 0.1 to 3.0% at room temperature with respect to a strip (band-shaped metal plate) rolled by a hot rolling mill (hot strip mill) or the like.
It is a rolling mill that applies flat light reduction and stretches the strip evenly to improve the flatness and surface texture and adjust the material. Structurally, for example, as shown in FIGS. 4A and 4B, a pair of work rolls 11
12 are arranged horizontally, and they are connected to the rolling-down means (hydraulic cylinder etc.) 15 and the frame-shaped housing 17 via the upper and lower backup rolls 13 and 14. The frame-shaped housings 17 _op and 17 _dr are arranged on both left and right sides of the line through which the strip x passes, that is, on each of the operation side and the drive side, and the compression means 15 _op and 15 _dr are also provided on each side. ing.

In relation to being used in a region where the rolling load is low as compared with a hot rolling mill or the like, in a skin pass mill, the strip is apt to meander. Since the load is low, there is a possibility that an error will occur between the actual load applied to the strip and the load detected by the load cell, and the effects of the gaps between machine parts will occur. It is not stable due to many factors. The direct cause of the meandering of the strip is that the rolling load acting from the reduction means via the work roll is not uniform on the left and right sides (operation side and drive side). When the rolling load becomes larger than the other on either the left or right side, the strip moves to the side where the load is smaller, causing a meandering. When the meandering becomes severe, the operation of the line has to be stopped, and depending on the degree and the frequency of occurrence of meandering, productivity may be significantly reduced and a serious situation may occur.

In order to prevent the meandering of the strip in the skin pass mill, the following means have been conventionally used. That is, a) The zero point is adjusted periodically with a constant load for the left and right rolling means. Since the rigidity of the housing (mill constant) is different between the operation side and the drive side,
Even if the work roll is rolled down to the same position (stroke) on each side, so-called difference in mill elongation occurs and the left and right rolling loads often do not match. Therefore, the zero point adjustment is performed by periodically rolling down the roll with a constant load (the same load on the left and right) and setting the stroke of each rolling down means at each reference point. Then, in the subsequent rolling, the amount of change in stroke with respect to the reference point is the same for each rolling means on the left and right. However, the conventional zero point adjustment is performed by pressing down the roll with a constant load such as 100 tons or 200 tons, which is determined for each skin pass mill. Except for special cases such as immediately after roll replacement, 1 It is carried out at regular time intervals such as once a day.

(B) The rolling amount (stroke) displacement and rolling force (load) in each rolling means on the left and right are monitored during rolling,
Appropriate automatic control is performed based on it. For example, in Japanese Patent Laid-Open No. 7-24515, there is a method of keeping the rolling force constant and a method of keeping the displacement constant when the deviation between the left and right sides of the displacement or rolling force to be monitored exceeds a predetermined amount. A meandering prevention method of switching control between them is described. The method described in the publication is basically based on rolling the strip with upper and lower work rolls as shown in FIG. 5 (a) with a constant rolling force, and the strip is biased to the left or right as shown in (b) ( That is, meandering occurs), the deviation of the rolling amount displacement is detected to be equal to or more than a predetermined amount, and the control system is switched to a displacement (stroke) to a predetermined value as shown in (c). When returning to the center as shown in d), it is detected that the deviation of the rolling force becomes equal to or less than a predetermined value, and the control system is switched to the constant rolling force again.

[0006]

The conventional method of preventing meandering in a skin pass mill is not sufficient in the following points. That is, a) In the method of periodically adjusting the zero point with a constant load for the left and right rolling-down means, a difference in mill elongation between right and left is likely to occur during actual rolling, and thus the strip meandering cannot always be prevented. The difference in mill elongation between left and right is likely to occur because the load during actual rolling does not always match the load during zero point adjustment. When the actual rolling load is different from the load at the time of zero point adjustment, the mill elongations on the operation side and drive side do not match those at the time of zero point adjustment, and the mill constants are slightly different between the left and right (sides). Based on what you do, they will be different. If there is a difference in mill elongation between the left and right during rolling, the result is that the left and right rolling loads will differ.
The strip tends to meander.

(B) In the case of adopting a method of automatically controlling by monitoring the rolling amount (stroke) displacement and rolling force (load) of each rolling means during rolling, a large number of precise control devices having high-speed performance are used. There is a considerable cost because it must be placed. Moreover, even if such a method is implemented at a high cost, it is difficult to obtain a sufficient effect. The effect is difficult to obtain, as described above, because an error is likely to occur between the actual load applied to the strip and the load detected by the load cell, and the difference between the operation side and the drive side. If you do not take any action to eliminate it, you can prevent the meandering due to the shape of the strip (the difference in the thickness between the left and right), etc., but also the meandering due to the left and right difference in the mill constant of the skin pass mill. It's difficult, because.

The invented method for preventing meandering is intended to provide a method for preventing meandering in a skin pass mill, which can effectively prevent meandering of a strip without using a high-grade control device.

[0009]

[Means for Solving the Problems] A meandering preventing method for a skin pass mill according to claim 1 is as follows: 1) After passing through a preceding material, before starting rolling of the next material (skin pass rolling) Rolls (including work rolls) are rolled down by the set rolling load (for each rolling means on the left and right) of the next material, and the zero point adjustment that sets the stroke (rolling position) of each rolling means at that time as the reference point 2) When rolling the next material (skin pass rolling), apply the set rolling load to the next material by rolling down the roll so that there is no difference in the stroke change from the reference point between the left and right rolling means. Is characterized by.

This meandering prevention method is similar to the above-mentioned method a) in that the zero point adjustment is performed for the left and right rolling-down means, but it is different from the method a) in the following points as described in 1) above. In other words, the zero point adjustment is not performed with the constant load set for each skin pass mill, but with the set rolling load of the next material, and it is not performed at fixed time intervals but after the passage of the preceding material and the next material. This is done before the start of rolling. That is, in this meandering prevention method, the zero point adjustment is carried out immediately before the start of rolling of the next material by the set rolling load of the next material.

During rolling, the skin pass mill undergoes some mill elongation, and the magnitude of the elongation is not necessarily equal between the left and right sides (that is, the operation side and the drive side). However, in the meandering prevention method of the present invention,
As in 1), the same load as in actual rolling is output to the left and right rolling means to perform zero point adjustment, and as in 2), the stroke change from the reference point set during zero point adjustment is left / right. Since there is no difference (that is, there is a difference in stroke between the left and right sides due to the thickness based on the strip thickness, but there is no difference between the left and right sides), rolling is performed by rolling down the rolls, so there is no load difference between the left and right sides. As long as the zero point adjustment is appropriately performed so as to satisfy the above conditions, the mill elongation during rolling matches that at the time of zero point adjustment, and there is almost no load difference between the left and right sides. Therefore, according to this method, it is possible to effectively prevent the meandering due to the structural characteristic of the skin pass mill (that is, the difference between the left and right mill constants).

This method of preventing meandering does not positively prevent meandering due to the shape of the strip, such as a portion of the strip where the left and right portions do not have the same thickness.
However, that is not a problem for the following reasons. That is, a) there is less meandering due to the shape of the strip due to improved shape control characteristics in hot rolling mills, etc., b) large load between zero point adjustment and actual rolling. Compared to the conventional meandering prevention method, which tends to cause a difference (several tons to tens of tons), the large mill elongation difference between the left and right sides due to the load difference is eliminated, so that the left and right sides based on the strip shape are eliminated. Even if there is a slight load difference or mill elongation difference, the effect of preventing meandering is sufficiently obtained.c) From the points a) and b) above, prevention of meandering caused by the shape of the strip, etc. It is also easy to correct the value by a manual operation of the operator (observing the meandering condition and appropriately operating the stroke of the rolling-down means).

In the meandering prevention method according to the second aspect of the present invention, in particular, during rolling, neither control based on a load difference between the left and right rolling means (automatic control) nor control based on a stroke difference between the rolling means (same as above) is performed. Characterize.

According to the first aspect of the present invention, since the meandering of the strip can be effectively prevented as described above, the stroke change of the rolling down means and the rolling down force of the rolling down means are monitored during rolling unlike the method of the above (b). No special automatic control is required. Therefore, even by the method of claim 2 which does not perform such control, it is possible to prevent the meandering due to the left-right difference of the mill constants in the skin pass mill, and reduce the problem of meandering due to the shape of the strip and the like. it can. Such a method does not require a device for monitoring a stroke or a rolling force or a control based on the stroke, and therefore has an advantage that a facility cost required for implementation can be suppressed. The control performed by monitoring the actual degree of meandering instead of the load difference or the stroke difference can be performed by a manual operation of an operator without using a special control device, and the effect is remarkable.

The method for preventing meandering according to claim 3 particularly
The above zero point adjustment is made constant by increasing the load by the left and right reduction means to the set rolling load of the next material and then making it uniform (that is, leveling so that the difference between the left and right is within 1%, for example). It is characterized in that the stroke of each rolling means is set as a reference point when the state is maintained for a time (for example, 5 seconds or more, and for practical purposes, for example, within 1 minute).

According to this method, it is possible to perform an appropriate zero point adjustment that satisfies the fact that there is no load difference between the left and right sides. This is because the outputs of the left and right rolling down means are made equal as described above to confirm the continuity for a fixed time. The skin pass mill housing is not a single piece,
Since the load (rolling down force) by the rolling down means acts on a plurality of members in the housing, a plurality of rolls, etc., each member elastically expands and contracts when a certain output is exerted on the same means. The load may change after a while because a slight deviation or permanent deformation may occur between them. Therefore, by confirming that the load does not change for several seconds, the load at the time of zero point adjustment can be accurately matched with the set rolling load of the next material, and the load difference between the left and right can be eliminated.

In the meandering prevention method according to claim 4, if the set rolling load of the next material is the same as that of the preceding material, the leading material is determined without performing zero point adjustment (1)). (That is, decided before starting rolling of the preceding material)
The following material is rolled using the reference point as the reference point of the next material (the above 2)).

As the set rolling load in the skin pass mill, a theoretically and empirically predetermined value is used according to the steel type, strip thickness and strip width of the strip to be rolled. The set rolling load of the next material is the same as that of the preceding material.
This is the case when the width and the like are the same. In such a case, the zero point adjustment is not performed again and the reference point defined for the preceding material is used, so according to this method,
When rolling with the same specifications is often continuous, the skin pass mill can be efficiently operated while preventing the strip from meandering.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows one mode for carrying out the invention.
~ Introduced in Figure 4. FIG. 1 is a flow chart showing a procedure for changing a steel plate (strip) to be rolled from a preceding material to a next material in a skin pass mill.
2 is a flowchart showing in detail the main part of the flow of FIG. 1 centering on the process of zero point adjustment. FIG. 3 is a layout diagram showing the entire skin pass line including the skin pass mill 10. FIG. 4 is a front view (FIG. 4A) and a side view (FIG. 4B) showing the structure of the skin pass mill 10.

The skin pass mill 10 is located in the skin pass line as shown in FIG. 3, and a strip (a strip steel plate) x rolled by a hot rolling mill (not shown) is lightly pressed to reduce the flatness of the plate. It is a rolling mill that improves the surface properties and adjusts the material quality. The structure of the skin pass mill 10 is shown in FIG.
As shown in (a) and (b), a pair of work rolls 1
1 and 12 are arranged horizontally, and they are connected to a pressure reducing means (hydraulic cylinder) 15 and a housing 17 via upper and lower backup rolls 13 and 14. The housing 17 has a frame-shaped housing 17 _op having substantially the same shape on each of the left and right sides (that is, the operation side and the drive side) sandwiching the line through which the strip x passes.
_{.17 dr} , and as the rolling down means 15, there are rolling down means 15 _{op.15 dr} of the same structure at the lower left and right _sides ,
Each is arranged inside the housing 17 _op · 17 _{d r} . If the stroke of the rolling means 15 _op · 15 _dr (the amount of expansion and contraction displacement of the cylinder) is increased and the lower backup roll 13 and work roll 12 are pushed up,
The strip x can be rolled down by applying a rolling load between the backup roll 14 and the work roll 12 which are constrained by the housing 17 _op · 17 _dr or the like. Then, the magnitude of the rolling load acting at that time is determined by a load cell (load cell) 16 _op. , Which is attached between the upper back-up roll 14 (each left and right bearings thereof) and each left and right housing 17 _op. 17 _dr. It can be known by 16 _dr . As the skin pass mill, it is possible to use one having a different number of rolls (or no backup roll) from the one shown in FIG. 4, or one having the rolling-down means on the upper part instead of the lower part.

As shown in FIG. 3, in the skin pass line, the strip x is unwound from the coil attached to the payoff reel 1 and passed through the skin pass mill 10.
Then, the strip x that has been subjected to the skin pass rolling is wound by the tension reel 8. Payoff reel 1
Between the skin pass mill 10 and the skin pass mill 10, a side guide 2 for guiding the strip x and a shear 3 for cutting are provided, and between the skin pass mill 10 and the tension reel 8, a thickness measuring means 4 for the strip x is provided. A width measuring unit 5, a surface texture inspection table 6 and a side guide 7 are arranged.

The pay-off reel 1 and the tension reel 8 are provided with position adjusting means 1a and 8a for the strip x, respectively. The position adjusting means 1a is for adjusting the position of the payoff reel 1 (coil of the payoff reel 1) to the left and right by using the hydraulic cylinder 1e. Measuring means 1c for calculating the amount of deviation (meandering amount) of the strip x,
And a control means 1d for operating the hydraulic cylinder 1e by obtaining the shift amount from the calculation result. Similarly, the position adjusting means 8a adjusts the horizontal position of (the coil of) the payoff reel 8 by the hydraulic cylinder 8e.
A combination of an optical sensor 8b for detecting the shift to the left and right, a shift amount (meandering amount) measuring unit 8c, and a control unit 8d for operating the hydraulic cylinder 8e according to the measurement result are combined. Since the position adjusting means 1a is attached to the pay-off reel 1, the strip x is correctly fed to the skin pass mill 10 near the left and right centers in the line of FIG.

However, even if the strip x is correctly fed before and after the skin pass mill 10 (upstream side / downstream side), if a load biased to the left or right in the skin pass mill 10 acts on the strip x, there will be left or right. The force toward the back acts on the strip x, and the meandering occurs. In order to prevent such meandering in the skin pass mill 10, the skin pass line of FIG. 3 takes the following measures. That is, when the supply of the strip x from the coil of the preceding rolled material (preceding material) is completed and the coil is switched to the coil of the next rolled material (next material), the line is stopped before the line operation is restarted. The specific operation shown in FIG. 1 and FIG. 2 is performed. The operation will be introduced below with reference to the configurations of the skin pass mill 10 and the skin pass line shown in FIGS. 3 and 4.

The outline of the operation for preventing the meandering is as shown in FIG. First, when the trailing edge of the coil (strip x) is detected by a sensor (not shown) arranged in the vicinity of the payoff reel 1 during operation of the skin pass line for the preceding material, the line is decelerated and stopped (step S
1 to S4). It is preferable to start decelerating the line when the remaining amount on the pay-off reel 1 is about 30 m, and stop the line when the tail end passes the skin pass mill 10 at about 1 m. Subsequently, the pressing means 15 is contracted to open the space between the work rolls 11 and 12, and then the strip x is slowly wound up by the tension reel 8 and waits for its tail end to pass through the skin pass mill 10 (steps S5 to S5). S6). Then, after the preceding material comes out from between the work rolls 11 and 12 of the skin pass mill 10, the zero point adjustment (zero adjustment) corresponding to the strip x (the next material) to be skin pass rolled next is performed in the skin pass mill 10. Perform (step SZ). When the zero adjustment is completed, the next material is sent from the payoff reel 1 to the skin pass mill 10, and the tip of the coil (strip x) is attached to the work rolls 11 and 12.
In the meantime, the pressing means 15 is further extended to press the strip x with the work rolls 11 and 12, and the tension reel 8 and the like are also activated to start the operation of the skin pass line (steps S17 to S23).

The details of the zero adjustment (step SZ) in FIG. 1 and the operations before and after it are shown in FIG.
The operation uses the computer on the machine side of the skin pass mill 10 to cause the skin pass mill 10 to function as in 1) to 8) below.

1) When the line stops near the tail end of the preceding material (step S4), the stroke of the rolling-down means 15 is displaced to open the work rolls 11 and 12 to make the roll gap about 15 mm (step S5). .

2) After the tail end of the preceding material has passed through the skin pass mill 10 (step S6), the data of the next material (steel type, plate thickness, plate width, etc.) and the set rolling load of the next plate are obtained from the host computer. Receive transmission (step S7).

3) When the set rolling load of the next material is received and it is judged that it is different from the value of the preceding material (step 8), zero adjustment is performed accordingly (step SZ), and if it is the same as the load of the preceding material. For example, without performing the zero adjustment, the next material is stored in the skin pass mill 10 while the data used for the preceding material (if the load of the preceding material is the same as that of the material preceding the material is stored) is stored. Pass through (step S17).

4) Zero adjustment is performed as follows. First, the stroke of the rolling means 15 is changed to change the work roll 11
・ Twelve spaces are closed, and each load cell 16 (16
with reference to the load by the _{op-16 dr)} gradually increased load between the rolls 11, 12, to reach the set rolling load of the next material received in step S7 (step S9-S10). Roll 11 - (measured value of the load meter _{16 op-16 dr)} load between 12 and reaches the set rolling load (step S10), and pressure means 15 ₍₁₅ o p-15
finely adjusting each rolling force of _dr ), and the load difference between the left and right, that is, the operation side and the drive side, is within a predetermined range (for example, 1% of the set rolling load, or 1 in absolute value).
Leveling is performed within a difference of 2 tons (steps S11 and S12). When the leveling is completed, the stroke (rolling down position) of the rolling down means 15 is held as it is, and it is checked whether or not the load is changed during holding (steps S13 and S14). That is, if the state where the load difference is within the above-mentioned predetermined range continues for a certain time (for example, 30 seconds) or more, it is considered that the zero adjustment is completed, and the rolling-down means 1 at that time is
The stroke of No. 5 is set as the reference point and stored in the computer on the machine side (step S15).

5) When the zero adjustment is completed by the above, the work rolls 11 and 12 are opened by the rolling-down means 15 to 1
Provide a roll gap of about 5 mm (step S1
6) Then, the threading of the next material strip x is started (step S17).

6) When the tip of the coil of the strip x passes through the skin pass mill 10 (step S18), the stroke of the rolling-down means 15 is extended by using the set rolling load received in step S7 as a target for reaching the rolling-down force. , Work rolls 11 and 12 closed and strip x
Is started (step S20). For the reduction, the left and right (that is, the operation side and the drive side) reduction means 15 _op and 15 _dr are synchronized, and the change in stroke from the reference point set and stored when the zero adjustment is completed is made the same amount (step S21). Each load cell 16 _op.16
This is performed by extending the stroke until the value of _dr reaches the set rolling load (step S22).

7) When the load reaches the set rolling load, the operation of the skin pass line is started (step S23).
The strokes during rolling in the left and right rolling-down means 15 _op and 15 _dr change from the reference point determined during zero adjustment by the amount corresponding to the strip thickness of the strip x, but are synchronized based on the reference point. Because it has been displaced (step S2
1) There is no difference between left and right. In addition, the load during rolling is the same as that for the zero adjustment with the reference point set, and it can be considered that there is no difference between the left and right sides. Therefore, there is no difference in mill elongation. Therefore, a uniform rolling load is always applied to the left and right of the strip x, and the meandering due to the structural left-right difference in the skin pass mill 10 is effectively prevented.

8) During operation, the strip x may cause a small amount of meandering due to its shape (thickness difference between left and right, etc.). Resolve it with manual intervention. That is, the worker finds the meandering by visual observation (step S24), and manually adjusts the stroke of the _rolling-down means 15 _op · 15 _dr so as to eliminate the deviation of the load between the left and right (step S25). . However, instead of such manual intervention, for example, a meandering sensor is arranged on the passage of the strip x to detect the meandering, and the control means for receiving the detection signal controls the stroke of the left and right pressing means 15 _op and 15 _dr . It is also good to let you do. At this time, as the meandering sensor, an optical sensor similar to that provided near the pay-off reel 1 or the tension reel 8 is used, and the control means has a constant meandering amount (the degree to which the strip x is laterally displaced). When the value exceeds the value, it is desirable to have a function of automatically calculating an appropriate stroke from the plate thickness and plate width, the feed rate of the strip x, the rolling load, etc. and sending a command to each of the rolling means 15 _op and 15 _dr. .

[0034]

According to the method for preventing meandering in the skin pass mill described in claim 1, there is almost no load difference between the left and right sides, that is, the operation side and the drive side during rolling, and the structural features of the skin pass mill are achieved. The resulting meandering is effectively prevented.

The meandering prevention method according to the second aspect does not require a device for monitoring the stroke or rolling load or controlling based on it, and thus has an advantage that the equipment cost required for the implementation can be suppressed.

In the meandering prevention method according to the third aspect of the present invention, the outputs of the left and right rolling down means are made equal and the continuity is confirmed for a certain period of time. It becomes possible to prevent the meandering more effectively.

According to the meandering prevention method of the fourth aspect,
When rolling with the same specifications is often continuous, it is possible to efficiently operate the skin pass mill while preventing the strip from meandering.

[Brief description of drawings]

FIG. 1 is a flowchart showing a procedure for changing a steel plate to be rolled from a preceding material to a next material in a skin pass mill.

FIG. 2 is a flowchart showing in detail a main part centering on a process of zero point adjustment in the flow of FIG.

FIG. 3 is a layout diagram showing the entire skin pass line according to the flow of FIGS. 1 and 2;

4A and 4B are a front view (FIG. 4A) and a side view (FIG. 4B) showing the structure of the skin pass mill 10 included in the skin pass line of FIG.

FIG. 5 is a schematic diagram showing a conventional meandering prevention method in a skin pass mill, and shows the control procedure in the order of FIGS.

[Explanation of symbols]

10 Skin pass mill 11.12 Work roll (roll) 15 (15 _{op.15 dr} ) Reduction means 16 (16 _{op.16 dr} ) Load cell SZ (step SZ) Zero adjustment (zero point adjustment)

Claims (4)

[Claims] 1. A batch type skin pass mill for guiding the tip of a coil for each coil is used, and after passing the preceding material and before starting the rolling of the next material, the rolls are rolled at a set rolling load of the next material by left and right reduction means. Is performed and the stroke of each rolling means at that time is set as a reference point.Zero adjustment is performed so that there is no difference in the stroke change with respect to the reference point between the left and right rolling means when rolling the next material. A method for preventing meandering in a skin pass mill, which comprises applying a set rolling load by rolling the roll down. 2. The method for preventing meandering in a skin pass mill according to claim 1, wherein during rolling, neither control based on a load difference between the left and right rolling means nor control based on a stroke difference between the rolling means is performed. 3. The zero point adjustment is performed by increasing the load by the left and right rolling down means to the set rolling load of the next material and then adjusting the strokes of the rolling down means so that the left and right loads are even, and keeping that state for a certain period of time. The method of preventing meandering in a skin pass mill according to claim 1 or 2, characterized in that the stroke of each rolling-down means is set at a reference point when is held. 4. If the set rolling load of the next material is the same as that of the preceding material, the reference point defined for the preceding material is used as the reference point of the next material without performing zero point adjustment, and the next material is rolled. The method for preventing meandering in a skin pass mill according to claim 1, wherein the method is performed.