JPH0468044B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for changing a rolling schedule when base metal coils of different sizes and steel types are welded at the entry side of a tandem rolling mill and are continuously rolled at their respective rolling schedules.

Up until now, rolling work using tandem rolling mills has been carried out in 1
The two coils were unwound on the entry side of the tandem while the top of the coil was passed through at low speed, wound on the exit side of the tandem, rolled at high speed and then decelerated, and finally the bottom of the coil was removed. However, this threading and shearing work causes many problems, such as reduced work efficiency, poor thickness accuracy at the top and bottom of the coil, resulting in an increase in off-gauge, and increased frequency of roll defects. Ta.
Therefore, recently, an operation method has been considered in which the base metal coils are sequentially welded on the entry side of the tandem, and rolled continuously, and multiple types of coils are connected and rolled, thereby eliminating the threading and tailing operations of the tandem rolling mill. ing.

However, the specifications of each base material coil are generally different, and therefore the rolling schedule is also different for each coil. For this reason, a technique for changing set values such as the rolling position and roll speed while rolling is becoming important.

As a conventional technology of this kind,
Publications No. 17145 and Japanese Patent Publication No. 55-11923 are known, but in both of these, when the schedule change point passes through each stand, the rolling position and roll speed of each stand are changed in advance. In this method, the set value is calculated in advance and the set value is changed according to this calculated value, but it has the following major drawbacks.

That is, the deformation resistance of the base coil is determined by various factors such as its material and hot-rolling winding temperature, but its value often varies depending on its longitudinal position even within one coil. This is due to skid marks, uneven baking, uneven cooling, uneven winding temperature, etc. that occur during the hot rolling process. Furthermore, it is clear that the cooling rate is different between the outer periphery and the center of the hot coil, and therefore the deformation resistance at the top of the coil varies particularly sharply. Furthermore, the thickness of the base coil is not uniform in the longitudinal direction. Similar to deformation resistance, this is caused by skid marks and uneven baking that occur in the hot rolling heating furnace, roll eccentricity in the hot rolling mill, top marks during coil winding, and the like. The tension between the stands fluctuates when the running schedule is changed due to deformation resistance or variations in the base material plate thickness at the top of the coil. Conventional running distance changing technology does not have a means to detect this tension fluctuation, so if the tension becomes too high, the plate may break, and if it becomes too low, it may cause suffocation, which can seriously impede operations. become. In particular, the running distance change point is often welded on the entry side, and even if the tension fluctuation is not extremely large, it often leads to plate breakage. Furthermore, when changing the running distance, the speed is often considerably higher than the threading speed in order to increase the production volume, which is an advantage of changing the running time, and when the above-mentioned trouble occurs, the damage is enormous.

Furthermore, when determining the amount of setting change, it is necessary to know the values of many parameters such as coil deformation resistance and friction coefficient. However, it is difficult to actually measure many of these parameters, and the amount of setting change is usually determined using their predicted values, and the settings are changed. However, in the prior art, since actual tension is not monitored, tension fluctuations caused by parameter prediction errors cannot be controlled, and the above-mentioned troubles may occur.

Furthermore, in the rolling schedule of each coil, the set value of the total tension between the stands may be considered to be determined approximately in proportion to the cross-sectional area of the coil. Therefore, when two coils with a large difference in plate thickness and/or plate width are welded together and continuously rolled in a tandem rolling mill, the tension setting values for the preceding coil and the succeeding coil are significantly different. In conventional travel distance changing technology, the reduction position roll speed is corrected as the schedule change point passes, but it is not possible to accurately synchronize the passing of the change point with the adjustment of the manipulated variable. possible, where transient tension fluctuations occur. This tension fluctuation increases as the difference in cross-sectional area between the two coils increases, and the above-mentioned troubles tend to occur. For this reason, it has been impossible to continuously roll coils with a large difference in cross-sectional area, which has been a major constraint on the production schedule.

In addition, one of the conventional techniques of this kind is known from Japanese Patent Publication No. 1983-49925, which changes the set value by changing the target values of plate thickness control and constant tension control. Although they tried to change it, they had the following major drawbacks.

Usually, when determining the outlet side plate thickness of each stand and the inter-stand tension for a predetermined base material thickness and finished thickness, they are determined so that the rolling load of each stand is in a desirable balance. If this load balance is disrupted, operational problems such as deterioration of the sheet shape or heat scratching of the rolls may occur, and rolling may become impossible. However, with the above technology, the finished plate thickness is detected by a thickness gauge installed at the exit side of the final stand, and using this and the detected value of each stand roll speed, the mass flow formula is used to estimate the plate thickness at the exit side of each stand. ing. However, this mass flow equation is a relational equation that only holds true when rolling at a constant speed.
When the roll speed of each stand changes, such as when changing the running distance, the plate thickness cannot be accurately estimated. For this reason, the estimated value of the plate thickness on the exit side of each stand is not accurate, and the reduction of each stand is changed based on this value, resulting in a large imbalance in the load of each stand. For this reason, it is conceivable to install a thickness gauge on the outlet side of each stand and measure the outlet side plate thickness of each stand, but this is impractical from the standpoint of equipment margin or equipment cost.
Another possible method is to calculate the thickness of each stand using a gauge meter, but this method also has poor detection accuracy and is not practical. This is due to roll heat-up and wear, errors in recognizing the zero point of the roll reduction position due to the thickness of the oil film on the roll bearings, nonlinearity of the mill stiffness curve, and the influence of the strip width, and it is quite difficult to overcome these problems. be.

For the reasons mentioned above, when the running distance was changed using this technique, there was a possibility that the load balance between the stands would be disrupted and rolling would become impossible. Furthermore, the thickness normally used is to detect the deviation of the actual thickness based on a predetermined target thickness, and when changing the target thickness of the thickness gauge,
It is necessary to interrupt the thickness gauge detection and change the settings. In this technique, since it is necessary to continuously detect the plate thickness using a thickness gauge, it is possible to change the plate thickness only within the deviation detection range for a certain set plate thickness. Normally this detectable range is ±500μ
However, in the case of a mill where the size of the base material coils to be rolled is wide-ranging, it is a constraint that is virtually impossible to achieve. .

The present invention was made in view of the shortcomings of the conventional rolling distance changing techniques as described above, and is a method for changing the rolling schedule of a tandem mill consisting of a plurality of stands that continuously roll welded coils.
Changing the running schedule, which eliminates fluctuations in tension between rolling stands that occur when schedules are changed, enabling stable operations, and eliminates plate thickness fluctuations that occur when schedules are changed, making it possible to significantly reduce off-gauge length. The purpose is to provide technology.

The present invention is a method for changing a rolling schedule from a preceding coil to a succeeding coil when sequentially welded coils are continuously rolled using a tandem mill composed of a plurality of stands, the rolling schedule being set in advance for the succeeding coil. The set value of the tension between rolling stands, the set value of the roll lowering position and the roll speed at each rolling stand are set at the time when the rolling schedule change point from the preceding coil to the following coil passes through each stand. /or By changing the roll speed, each setting value set for the preceding coil is changed to each setting value of the following coil in a tapered manner, and at that time, the changing point is at the center of the tapered shape. At the same time, at the stage of changing the tension, roll reduction position, and roll speed to each set value, the coil tension between the rolling stands is detected, and at that point in the middle of changing the tension. Calculate the deviation from the midway target value, and based on this deviation, adjust the roll reduction position and/or roll speed so that the detected value matches the midway target value at that point. Constant tension between rolling stands This is a rolling schedule changing method characterized by performing control.

According to one embodiment of the present invention, the inter-stand tension constant control is performed by comparing the output of a tension meter installed between each stand with the inter-stand tension target value to obtain a deviation, and based on this deviation. This is done by correcting the roll speed of all stands on the upstream or downstream side between the stands.

According to another embodiment of the present invention, the inter-rolling stand tension constant control calculates a deviation by comparing the output of a tension meter installed between each stand with a target inter-rolling stand tension value, and calculates the deviation. This is done by correcting the lowering position of the downstream stand between the stands based on this.

Furthermore, from another aspect, the present invention provides a method for changing the rolling schedule from a preceding coil to a subsequent coil when sequentially welded coils are continuously rolled using a tandem mill composed of a plurality of stands, comprising: The target value of the inter-stand tension set in advance for the subsequent coil, the target value of the roll reduction position and roll speed at each rolling stand, and the target value of the exit side plate thickness at each rolling stand are obtained from the other coils. When the rolling schedule change point for the following coil passes through each rolling stand, by changing the roll rolling position and/or roll speed, the four types of the following coils are changed from each target value set for the preceding coil. The change start timing is determined so that the change point at that time is in the center of the taper shape, and at the same time, the tension, roll reduction position, roll speed, and exit plate At the stage of changing the thickness to each target value, the coil tension between the rolling stands is detected, the deviation from the target value at that point in the process of changing the tension is determined, and the detection is performed based on this deviation. Inter-stand tension constant control is performed to adjust the roll rolling position and/or roll speed so that the rolled-down value matches the intermediate target value at that point, and at the same time, the exit side plate thickness of the relevant rolling stand is detected. , find the deviation from the intermediate target value at that point in time during the change of the exit side plate thickness, and based on this deviation, adjust the roll reduction position so that the detected value matches the intermediate target value at that point. This is a rolling schedule changing method characterized by adjusting the rolling schedule.

Hereinafter, the present invention will be described using a five-stand tandem rolling mill as an example with reference to the accompanying drawings.

FIG. 1 shows an example of a five-stand tandem rolling mill, in which a strip ST is rolled by five stands from the first stand 1 to the fifth stand 5. 11 to 15 are roll-down position setting devices for each stand, and a roll-down position target value command device 31
- Set the lowering position according to the commands 35. 21
-25 are roll drive motors of each stand, which drive the rolls at the command speeds of the roll speed target value command devices 41-45. Further, 26 to 30 are roll speed detection devices for each stand.

The rolling position target value commanding devices 31 to 35 determine the rolling position target value for each stand based on the outputs of the rolling position change pattern calculation devices 61 to 65 and the tension constant control devices 51 to 54 of the front stands, respectively. It is output to the rolling position setting devices 11 to 15.
Further, the constant tension control devices 51 to 54 control the actual tension values detected by the tension meters T1 to T4 installed between each stand and the tension values that are the output values of the tension set value change pattern calculation devices 71 to 74. The inter-stand tension is made equal to the tension target value by comparing the target values and outputting an output corresponding to the deviation to the roll-down position target value command devices 32 to 35 of the downstream stands.

The tension target value that is being changed, that is, the intermediate target value, is compared with the actual value each time, and deviations are corrected. Such tapered changes are performed using each intermediate target value at that point until a preset final target value is achieved, and after the final target value is achieved,
In other words, after passing the change point, constant tension control is performed based on the final setting value.

Roll speed target value command devices 41-45 determine roll speed target values for each stand based on the outputs of roll speed change pattern calculation devices 81-88, and output them to roll drive motors 21-25.

The reduction position change pattern calculation devices 61 to 65 are based on the output of the set value change amount calculation device 100 and the output of the set value change timing command devices 91 to 95.
A change pattern of the lowering position of each stand is calculated and the calculation results are output to the lowering position target value command devices 31 to 35.

Tension set value change pattern calculation devices 71 to 74 calculate a change pattern for the tension set value between each rolling stand based on the output of the set value change amount calculation device 100 and the output of the set value change timing command devices 91 to 95. The calculation results are output to constant control devices 51-54.

The roll speed change pattern calculation devices 81 to 88 calculate the successive roll speed of each stand with the third stand as the pivot stand based on the output of the set value change amount calculation device 100 and the output of the set value change timing command devices 91 to 95. The change pattern is calculated and the calculation results are successively output to the roll speed target value command devices 41 to 45.

Setting value change timing command device 9 for each stand
1 to 95 are based on the change start timing and change time of the previous stand setting value, which are the outputs of the upstream stand setting value change timing calculation device, and the outputs of the speed detection devices 26 to 29 of the respective stand roll drive motors 21 to 25. Calculate the stand set value change start timing and change time, and output the calculation results to the rolling position change pattern calculation devices 61 to 65, the tension setting value change pattern calculation devices 71 to 75, and the roll speed change pattern calculation devices 81 to 88. . The set value change timing command device 90 at a schedule change point determines the timing at which a schedule change point such as a base metal welding point reaches the first stand or the timing at which it reaches a predetermined position on the entrance side of the first stand as a first stand set value. It is output to the change timing command device 91.

The set value change amount calculation device 100 calculates in advance the amounts to be changed in each stand rolling position, tension target value, and roll speed when the schedule change point passes through each stand before the change point reaches the tandem rolling mill. Calculate it. This is obtained by repeatedly performing known path schedule and setup calculations. For example, the amount by which the rolling position of each stand should be changed is ΔSi = S _Bi - S _Ai , where ΔSi: the amount of change in the rolling position of the i-th stand S _Ai : the preceding coil (change S _Bi : Calculated from the known pass schedule and the set value of the rolling position of the subsequent coil (after passing the change point) determined by setup calculations. The same applies to the amount by which the tension target value and roll speed should be changed. The calculation results are output to the rolling position change pattern calculation devices 61 to 65, the tension setting value change pattern calculation devices 71 to 74, and the roll speed change pattern calculation devices 1 to 88.

As described above, a plurality of manipulated variables such as the rolling position, roll speed, and tension setting value are simultaneously changed by the set value change timing command devices 91 to 95 of each stand. As an example, in the case of the second stand setting value change timing command device indicated by reference numeral 92 in FIG. The set value of the tension between the first and second stands is determined by the roll speed change pattern calculation device 82 through the value change pattern calculation device 71.
Through this, the roll speed of the first stand is changed, and through the roll speed change pattern calculation device 83, the roll speed of the second stand is changed simultaneously.

Here, the functions of the setting value change timing command device and the reduction position change pattern calculation device of each stand will be described using the mass reduction position as an example with reference to FIG.

Figure 2 shows the set value change timing command device 91~
95, which shows the outputs of the reduction position change pattern calculating devices 61 to 65 operated in accordance with the command 95, and gives the change pattern of each manipulated variable as a function of time as shown in the figure.

This is referred to herein as a tapered change pattern, and changing according to this change pattern is referred to as "tapered change."

Regarding the change start timing _t1 , the change start points on the strip are matched by tracking using the roll speed of each stand. Furthermore, by giving the length of the changing taper portion on the strip at the exit side of the fifth stand shown in FIG. 2 and determining the time required for changing at each stand, it is also possible to determine the timing at which the changing ends. The length of the change taper portion or the time required for change at each stand may be calculated by the set value change calculation device 100 and given to the set value change timing command devices 91 to 95 so that the change point is at the center of the taper. .

The taper length can be determined by determining the maximum change speed of the rolling position and roll speed and the required change amount.The taper length is determined in advance for each change amount or coil size, and then the taper length is determined in advance for each change amount or coil size. Possible methods include determining the taper length according to the amount or coil size, or a combination of these methods. The change start timing of the first stand is determined based on the output of the set value change timing command device 90 in schedule change so that the change point is in the center of the change taper part.
Changing the first stand may be started at the timing when the PB (push button) is pressed.

The rolling position change pattern calculating devices 61 to 65 have been described above with reference to FIG. 2, but the rolling position changing pattern calculating devices 71 to 75 and roll speed changing pattern calculating devices 81 to 88 also Arithmetic devices 61-6
5 is different only in that the calculation target quantities are the tension setting value and roll speed setting value, respectively, and the calculation content is to repeat the known pass schedule and setup calculation, and the rolling position change pattern calculation device It is exactly the same as 61-65.

Next, by the method of the present invention shown in FIG.
Describe in detail how schedule changes are implemented. Now, the preceding coil A and the following coil B
An example will be explained in which the rolls are contacted at the entry side of the tandem and rolled continuously. First, consider the state before welding point X between coil A and coil B reaches the first stand. At this time, rolling position change pattern calculation devices 61 to 65, tension setting value change pattern calculation devices 71 to 74, roll speed change pattern calculation device 8
The outputs 1 to 88 are all set values according to the rolling schedule of the coil A, and these are the rolling position target value command devices 31 to 35, the constant tension control devices 51 to 54, and the roll speed target value command device 41, respectively. ~45 is output. Then, the tension constant control devices 51 to 54 output a reduction position correction signal to the reduction position target value command devices 32 to 35, respectively, in order to maintain the actual tension at the set tension of the A coil. Further, the set value change amount calculation device 100 has already calculated how much the set value should be changed each time the change point X passes through each stand, based on the rolling schedule of the A coil and the B coil. and each change pattern calculation device 61-65, 71-7
4, 81-88. That is, the set value of the tension between the first and second stands, the roll lowering position and the roll speed at the first stand for the succeeding coil B are set in advance, but the set value change timing command devices 91 to 95 change them. Changes will not start until a start command is issued. Now, when the change point X approaches the first stand, the set value change timing command device 91 outputs a change start command to the rolling position change pattern calculation device 61 and the roll speed change pattern calculation device 81. The roll position change pattern calculation device 61 calculates a roll position change pattern for changing a predetermined amount of change at a predetermined change speed, and outputs a roll position change pattern via the roll position target value command device 31 and the roll position setting device 11 to the first roll position change pattern. Change the stand's downward position to the B coil setting value in a tapered manner. In addition, the roll speed change pattern calculation device 81 also uses the same method to compensate for the change in the advance rate of the first stand.
The first stand roll speed is changed in a tapered manner in synchronization with the change in the rolling reduction. That is, when changing the following coil B to the three preset values, when the rolling schedule change point from the preceding coil to the succeeding coil passes through each stand, the roll reduction position and/or roll speed is changed. Change to tapered shape. At this time, the change start timing is determined so that the change point X, that is, the junction point between the A coil and the B coil, is located at the center of this tapered shape. Therefore, even if the synchronization accuracy between the timing of passing the change point and changing the set value is slightly poor, stable running distance changes can be carried out without excessive tension fluctuations. This setting change starting point at the first stand is tracked and transmitted to the setting value change timing command device 92 at the second stand.

In the second stand, as in the first stand, a predetermined change amount is changed at a predetermined change time. The change when passing the second stand is timed to occur at the same point on the strip where the change when passing the first stand was made. When passing through the second stand, the tension setting value between the first and second stands is changed in a tapered manner, together with the roll lowering position of the second stand and the first and second stand roll speeds, to become the B coil setting value. During this time, the first and second
Constant tension control between stands is always performed, only the target value changes in a tapered manner, and constant tension control is performed based on the intermediate target value at each point during the change, and after the change is completed. is constant tension control with the B coil set value as the target.

Here, the effect of this constant tension control function will be explained in more detail. The schedule change point, that is, before and after the welding point of the base metal coil, corresponds to the top or bottom part of the base metal coil, and the deformation resistance and plate thickness in the longitudinal direction of the coil vary significantly. For example, when the change point X passes through the second stand, if the deformation resistance before and after it is higher than the set value, the front-to-back ratio will be small and excessive tension will be applied between the first and second stands. At the same time, the thickness of the plate on the exit side of the second stand also increases. If constant tension control is not performed, this excessive tension may cause the plate to break. This possibility is particularly high before and after the welding point.
On the other hand, if the tension is too small, it tends to cause narrowing.

However, as in the present invention, if tension constant control is performed while changing the tension target value in a tapered manner even near the change point, such a situation can be prevented and stable running distance changes can be implemented.

That is, to explain using the above example, it is detected that the tension between the first and second stands is too high, and based on this, the second stand is moved to the lowered position. That is, at the stage of changing the tension setting value, roll rolling position setting value, and roll speed setting value,
The coil tension between the first and second stands is detected, the deviation from the target value at that point in time during the tension change is determined, and based on this deviation, the detected value is determined from the target value at that point. A constant tension control between rolling stands is performed to adjust the roll rolling position and/or roll speed so as to match. As a result, the tension between the first and second rolling stands is maintained at the target value, and the plate thickness at the exit side of the second stand is also reduced, approaching the target value. Thereafter, when the change point X passes through the third, fourth, and fifth stands, a similar taper-like setting change is performed, and during this time, tension constant control between each stand is also continuously performed.

In this way, for each rolling stand, the set value of the inter-stand tension set in advance for the succeeding coil, the set values of the roll reduction position and roll speed at each rolling stand are adjusted from the preceding coil to the succeeding coil. When the schedule change point passes through each stand, by changing the roll reduction position and/or roll speed, the schedule changes from each setting value set for the preceding coil to each setting value of the following coil, respectively, in a tapered shape. At that time, the change start timing is determined so that the change point is at the center of the tapered shape. detect the coil tension, find the deviation from the target value at that point in time during the change of the tension, and based on this deviation, change the coil tension so that the detected value matches the target value at that point in time. A constant tension control between rolling stands is performed to adjust the roll rolling position and/or roll speed.

The method of the present invention has been explained above using FIG. 1 as an example, but from the viewpoint of reducing the off-gauge length,
A method of providing various additional devices as shown in the figure is also effective.

Figure 3 shows only the first stand in Figure 1, and shows the same device as Figure 1.
It is assumed that the same equipment as in FIG. 1 is set for the parts after the second stand which are not shown in the figure.

In FIG. 3, A is a first stand outlet side plate thickness detection device, B is a plate thickness control device, C is a plate thickness set value change pattern calculation device, and D is a plate thickness set value change timing command device. The plate thickness control device B corrects the first stand lowering position in order to target the outlet side plate thickness of the first stand, but when the change point passes directly under the plate thickness detection device A, the change taper Accordingly, the target value of the plate thickness is also changed into a tapered shape, and the first stand lowering position is to be corrected accordingly.

With regard to such control of the plate thickness target value, as in the case of constant tension control, a comparison with the plate thickness actual value is performed each time based on the intermediate target value at each point in time during the plate reduction change.

As the plate thickness detection device A, as shown in Fig. 3, an X-ray thickness meter installed apart from the stand may be used, or the plate thickness directly under the stand may be detected by calculating the plate thickness with a gauge meter. good. Although FIG. 3 has been described using the first stand as an example, it goes without saying that the same method can be applied to the second and subsequent stands.

Further, as shown in FIG. 4, the outputs of the constant tension control devices 51 to 54 may be input to the roll speed target value command devices 41 to 45 using the roll speed as the manipulated variable for constant tension control.

Furthermore, as shown in FIG. 5, it is also possible to change the tension setting value in two stages: the timing when the schedule change point reaches the upstream stand, and the timing when the schedule change point reaches the downstream stand. That is, in FIG. 5, in addition to the control system shown in FIG. 1, there are also devices 66 to 66 that calculate the rolling position change pattern and the tension setting value change pattern at the timing when the schedule change point reaches the upstream stand.
69 and 75-78 are provided. By using this method, when the difference between the tension setting values of the preceding coil and the succeeding coil is large, the tension can be changed in two stages. Further, by lowering the target tension value between the stands passing through the welding point, it is possible to prevent the plate from breaking as described above.

FIG. 6 shows an embodiment of the present invention.

Figure 6a shows the running distance changed using the method of the present invention, and Figure 6b shows the conventional method (Japanese Patent Publication No. 48-17145).
The running distance was changed using the following publication. a and b are changes in running distance under the same conditions; the preceding coil has a base metal thickness of 3.8 mm, a finished thickness of 1.585 mm, and a plate width of 1413 mm; the following coil has a base metal thickness of 3.0 mm, a finished thickness of 0.790 mm, and a plate width of 1413 mm. Width 1413mm, running distance change speed is
It was 212mpm. Although the materials of the preceding coil and the succeeding coil were the same, the deformation resistance varied greatly at the tip of the succeeding coil. Each stand exit plate thickness,
A chart of the tension stress between each rolling stand is shown, and each chart shows the change in deviation based on the value of the preceding coil.

In the conventional method, the tension fluctuates drastically when passing the welding point and at the tip of the succeeding coil, which is a major hindrance to operation. In addition, the plate thickness fluctuations are large, and a large amount of off-gauge occurs.

In contrast, an example of the operation of each manipulated variable in FIG. 6a, which is an embodiment of the present invention, will be explained in accordance with the timing at which the setting change start point passes through each stand. First, at the timing when the setting change start point begins to pass through the #1 stand, start changing the roll reduction position of the #1 stand in a taper shape, and set the change start timing so that the change point at that time is in the center of the taper shape. , the stand exit plate thickness deviation of #1 stand is changed. Next, at the timing when the setting change start point begins to pass through stand #2, the tension set value between stand #1 and stand #2 starts changing at the same time as the roll lowering position of stand #2 is changed in the same manner. . At this time, change of the roll speed of the #1 stand is also started in the same manner. In this way, the plate thickness deviation on the stand exit side of the #2 stand is changed. Furthermore, the starting point for changing settings is #3
At the timing when the roller starts passing through the stands, the tension set value between the #2 stand and the #3 stand starts to be changed at the same time as the tapered roll rolling position of the #3 stand is changed. At this time, the roll speeds of stand #1 and stand #2 may be successively changed in synchronization. In this way, the thickness deviation of the stand exit side of the #3 stand is changed. Thereafter, the stand outlet plate thickness deviation is changed in the same manner in the #4 stand and the #5 stand.

In this manner, in the method of the present invention, there is little excessive fluctuation in tension, and the tension is stably controlled to the target tension value. The board thickness is also stable.

It is clear from this example that the method of the present invention is extremely useful in practice when performing connected rolling and changing the running schedule of a tandem rolling mill.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a control system when implementing the method of the present invention on a five-stand tandem rolling mill. FIG. 2 illustrates an example in which the target tension value, the target roll position value, and the target roll speed value are changed in a tapered manner according to the present invention. FIG. 3 is a schematic diagram of an apparatus for carrying out a method according to one aspect of the invention. Furthermore, FIGS. 4 and 5 are each a schematic illustration of an apparatus for carrying out a method according to another aspect of the invention. FIGS. 6a and 6b are graphs showing the exit side plate thickness deviation and inter-stand tension stress deviation when the method of the present invention and the conventional method are implemented, respectively. (Main reference numbers) 11-15: Roll down position setting device, 21-25: Roll drive motor, 31-3
5: Rolling position target value commanding device, 41 to 45: Roll speed target value commanding device, 51 to 54: Tension constant control device, 61 to 65: Rolling down position change pattern calculation device, 71 to 74: Tension target value changing pattern calculation Devices, 81-88: Roll speed change pattern calculation device, 91-95: Setting change timing command device, 100: Setting value change amount calculation device.

Claims (1)

[Scope of Claims] 1. A method for changing the rolling schedule from a preceding coil to a succeeding coil when sequentially welded coils are continuously rolled using a tandem mill consisting of a plurality of stands, comprising: The set value of the inter-stand tension, the set value of the roll rolling position and the roll speed at each rolling stand are set at the time when the rolling schedule change point from the preceding coil to the succeeding coil passes through each stand. By changing the position and/or roll speed, each setting value set for the preceding coil is changed to each setting value of the following coil in a tapered manner, and at that time, the changing point is at the center of the tapered shape. At the same time, at the stage of changing the tension, roll reduction position, and roll speed to each set value of the succeeding coil, detect the coil tension between the rolling stands, and determine the tension. Find the deviation from the target value at that point in the process of changing, and based on this deviation,
A method for changing a rolling schedule, characterized by performing constant tension control between rolling stands, which adjusts a roll rolling position and/or a roll speed so that a detected value matches a target value at that point in time. 2. The inter-rolling stand tension constant control compares the output of the tension meter installed between each stand with the inter-stand tension target value to find a deviation, and based on this deviation, the The rolling schedule changing method according to claim 1, which is carried out by modifying the roll speed of all stands on the side. 3. The inter-rolling stand tension M constant control compares the output of the tension meter installed between each stand with the target inter-rolling stand tension value to find a deviation, and based on this deviation, the downstream A rolling schedule changing method according to claim 1, which is carried out by correcting the rolling position of a side stand.