JP7518385B2 - Processing device, processing method, and program - Google Patents

Description

The present invention relates to a processing device, a processing method, and a program, and is particularly suitable for executing running speed setting changes in a tandem rolling mill.

In the rolling process of plate materials using a tandem rolling mill equipped with multiple rolling mills, in order to improve rolling efficiency and yield, before rolling multiple rolled materials lined up in the rolling sequence, the front end of the rolled material is joined to the rear end of the rolled material that is rolled just before it by welding or the like, and the multiple rolled materials are continuously supplied to the tandem rolling mill, and are continuously rolled without stopping the tandem rolling mill.

In the following description, of the two rolled materials joined together as described above, the rolled material present downstream in the conveying direction of the rolled material is referred to as the leading material, and the rolled material present upstream is referred to as the trailing material. The downstream and upstream sides of the conveying direction of the rolled material are simply referred to as the downstream side and the upstream side, respectively. The area where the leading material and the trailing material are joined is referred to as the welding point. The specifications of the rolled material may change from the specifications of the leading material to the specifications of the trailing material at the boundary of this welding point. In this case, in order to continuously roll multiple rolled materials without stopping the rolling mill, it is necessary to change the settings of the rolling mill, such as the roll down position (the gap between the upper and lower work rolls when no load is applied) and the roll speed (the rotation speed of the work roll) of each rolling mill, from the settings of the leading material to the settings of the trailing material when the welding point passes through the rolling mill. Changing the settings of the rolling mill without stopping the rolling mill in this way is called a running setting change. In addition, because the change process for changing the running speed setting requires a certain amount of time (running change time), it often starts before the welding point reaches the rolling mill and ends after the running change time has elapsed.

As a technique for changing the rolling position and the roll speed, there is a technique disclosed in Japanese Patent Laid-Open No. 2003-233996.
Here, among the tandem rolling mills consisting of three rolling mills arranged consecutively in the conveying direction of the rolled material, the most upstream rolling mill is referred to as the j-1 rolling mill, the middle rolling mill is referred to as the j rolling mill, and the most downstream rolling mill is referred to as the j+1 rolling mill. In addition, the time period from the end of the running speed setting change executed when the welding point passes through a certain rolling mill to the start of the running speed setting change executed when the welding point passes through the next rolling mill is a time period during which the running speed setting change is not executed, and this time period is referred to as a steady state time period. Patent Document 1 discloses that in the steady state time period during which the welding point is conveyed from the j-1 rolling mill to the j rolling mill, the tension of the rolled material between the j-1 rolling mill and the j rolling mill is set to the tension setting value of the preceding material, and the reduction position and the roll speed are changed based on this setting value.

Here, the set value of the tension of the preceding material between the j-1th rolling mill and the jth rolling mill is denoted as T _j-1 ^I. Also, the set value of the tension of the following material between the j-1th rolling mill and the jth rolling mill is denoted as T _j-1 ^II . Also, the set value of the tension of the preceding material between the j-1th rolling mill and the jth rolling mill is simply abbreviated to the tension set value of the preceding material, and the set value of the tension of the following material between the j-1th rolling mill and the jth rolling mill is simply abbreviated to the tension set value of the following material.

In Patent Document 1, the tension of the following material at the delivery side of the j-1st rolling mill which is rolling the following material is not the set value T _j-1 ^II of the tension of the following material, but the set value T _j-1 ^I of the tension of the preceding material. That is, the tension of the following material is T _j- 1 ^I /T j-1 ^II times the set value T j-1 ^II of the tension of the following material. Therefore, when T _{j-1 I} ^/ T _{j -1} ^II is large, an excessive tension is applied to the following material. As a result, there is a risk that the following material will break.

As a countermeasure against this, there is a technique disclosed in Patent Document 2. When the value (tensile stress) obtained by dividing the tension applied to the plate-shaped rolled material by the cross-sectional area of the rolled material is the same, the thicker the thickness of the rolled material, the greater the tension, and the thinner the thickness of the rolled material, the smaller the tension. Patent Document 2 focuses on this and states that T _j-1 ^I /T _j-1 ^II becomes large when the thickness of the preceding material is thicker than that of the succeeding material, that is, when the rolled material in the jth rolling mill is changed from a thick material to a thin material. In such a case, the tension of the rolled material between the j-1th rolling mill and the jth rolling mill, where the welding point between the preceding material and the succeeding material exists, is set to a value at which the rolled material does not break. Specifically, it is shown that the set value of the tension of the succeeding material between the j-1th rolling mill and the jth rolling mill is used as the value at which the rolled material does not break.

However, neither of the techniques in Patent Documents 1 and 2 takes into consideration the change in tension of the rolled material during changes in the rolling position and roll speed of the rolling mill (hereinafter, during change in running speed setting). One technique that takes this into consideration is the technique disclosed in Patent Document 3.

In Patent Document 3, the tension fluctuation of the rolled material during the change of the reduction position and roll speed is predicted, and the time from when the travel setting change, which is performed when the welding point passes through the rolling mill, is started to when the welding point reaches the rolling mill (hereinafter, appropriately, referred to as the preceding material travel change time) is optimized, thereby controlling the tension fluctuation of the rolled material during the change of the reduction position and roll speed.

The steady-state time period during which the weld point is transported from the j-1th rolling mill to the jth rolling mill is called the jth generation. The steady-state time period during which the weld point is transported from the jth rolling mill to the j+1th rolling mill is called the j+1th generation.

FIG. 9 is a diagram for explaining the technology described in Patent Document 3. Specifically, FIG. 9 is a diagram that shows a schematic diagram of the change in tension of the rolled material over time when the generation is updated from the jth generation to the j+1th generation. In FIG. 9, the tension between the j-1th and jth rolling mills indicates the tension of the rolled material between the j-1th rolling mill and the jth rolling mill. The tension between the jth and j+1th rolling mills indicates the tension of the rolled material between the jth rolling mill and the j+1th rolling mill. _{T j-1} ^(j) indicates the tension of the rolled material between the j-1th rolling mill and the jth rolling mill in the jth generation. _{T j-1} ^(j+1) indicates the tension of the rolled material between the j-1th rolling mill and the jth rolling mill in the j+1th generation, and is equal to the set value T _j-1 ^II of the tension of the following material between the j-1th rolling mill and the jth rolling mill. T _j ^(j) indicates the tension of the rolled material between the jth rolling mill and the j+1th rolling mill in the jth generation, and is equal to the set value T _j-1 ^I of the tension of the preceding material between the j-1th rolling mill and the jth rolling mill. T _j ^(j+1) indicates the tension of the rolled material between the jth rolling mill and the j+1th rolling mill in the j+1th generation. The subscripted symbol (j-1, j) and the superscripted symbols ((j), (j+1), I, II) to the right of the symbol correspond to the symbols shown stacked above and below in FIG. 9. The same method of notating the symbols applies to other variables.

The weld point jth rolling mill arrival timing indicates the timing when the weld point reaches the jth rolling mill. a indicates the weld point jth rolling mill arrival timing when the preceding material travel time is set to 0. b indicates the weld point jth rolling mill arrival timing when the preceding material travel time is set to 1/2 of the travel time. c indicates the weld point jth rolling mill arrival timing when the preceding material travel time is equal to the travel time. Also, in Figure 9, the trajectories of the tension of the rolled material over time for the weld point jth rolling mill arrival timings a, b, and c are shown with arrows a, b, and c. As shown in Figure 9, when the preceding material travel time is changed, the trajectory of the tension of the rolled material within the travel time changes. Therefore, by optimizing the preceding material travel time, it is possible to control the tension fluctuation of the rolled material during the change of the roll position and roll speed.

In FIG. 9, when the welding point reaches the jth rolling mill at a, the preceding material travel time is 0 (i.e., the travel setting change starts when the welding point passes the jth rolling mill). When the welding point reaches the jth rolling mill at b, the preceding material travel time is the period from the start of the change in the reduction position and roll speed to b. When the welding point reaches the jth rolling mill at c, the preceding material travel time is the period from the start of the change in the reduction position and roll speed to c (i.e., the preceding material travel time and the travel time are equal).

Patent No. 2800993 Special Publication No. 3-66964 Patent No. 3438335

However, in the method of Patent Document 3, the preceding material travel time is optimized based on the set value of the tension of each generation of the rolled material as shown in Patent Documents 1 and 2, so that no matter how the preceding material travel time is selected, the tension fluctuation of the rolled material may not be controlled to a desired state. This is because, in FIG. 9, the tension T _j-1 ^(j) between the j-1st and jth rolling mills at the rolling position and the timing at which the roll speed change starts, and the tension T _j ^(j+1) between the j-th and j+1st rolling mills at the rolling position and the timing at which the roll speed change ends are determined and fixed by the set value of the tension of the preceding material or the following material, and the preceding material travel time is optimized only under the condition that the tension of the rolled material before and after the travel time is fixed. Therefore, if the tension of the rolled material becomes too high, there is a risk of the rolled material breaking, and if the tension of the rolled material becomes too low, there is a risk of the rolled material meandering or deterioration of the flatness. As a result, rolling may not be able to continue.

The present invention was made in consideration of the above problems, and aims to suppress tension fluctuations in the rolled material when changing the running speed setting in a tandem rolling mill.

The processing device of the present invention is a processing device for executing a running speed setting change that changes the setting value of a target rolling mill when a joint that joins multiple rolled materials in a transport order passes through a target rolling mill among tandem rolling mills, and is equipped with a setting calculation means that determines the setting value of the target rolling mill based on an evaluation function that evaluates the degree of tension change of the two rolled materials joined at the joint when the running speed setting change is executed for the target rolling mill, and the evaluation function includes an evaluation index determined using a first decision variable and a second decision variable, the first decision variable is a variable for determining the timing when the joint reaches the target rolling mill between the start and end of the running speed setting change, and the second decision variable is a variable for determining the tension of the two rolled materials between the target rolling mill and the rolling mill one upstream of the target rolling mill at the start of the running speed setting change of the target rolling mill, and the setting calculation means determines the value of the first decision variable and the value of the second decision variable when the value of the evaluation function is maximum or minimum.

The processing method of the present invention is a processing method for executing a running speed setting change that changes the setting value of a target rolling mill when a joint that joins multiple rolled materials in a transport order passes through a target rolling mill among tandem rolling mills, and includes a setting calculation step of determining the setting value of the target rolling mill based on an evaluation function that evaluates the degree of tension change of the two rolled materials joined at the joint when the running speed setting change is executed for the target rolling mill, the evaluation function includes an evaluation index determined using a first decision variable and a second decision variable, the first decision variable is a variable for determining the timing when the joint reaches the target rolling mill between the start and end of the running speed setting change, the second decision variable is a variable for determining the tension of the two rolled materials between the target rolling mill and the rolling mill one upstream of the target rolling mill at the start of the running speed setting change of the target rolling mill, and the setting calculation step determines the value of the first decision variable and the value of the second decision variable when the value of the evaluation function is maximum or minimum.

The program of the present invention is intended to function as the setting calculation means.

According to the present invention, it is possible to suppress the tension fluctuation of the rolled material during the change of the running speed setting in a tandem rolling mill.

FIG. 11 is a diagram showing an example of the change in the rolling state with respect to time when the tension in the steady state and the preceding material running time are not optimized. FIG. 11 is a diagram showing an example of the timing for changing the rolling position of each rolling mill when the tension and the preceding material travel time in a steady state are not optimized. FIG. 11 is a diagram showing an example of the timing for changing the roll speed of each rolling mill when the tension and the preceding material travel time in a steady state are not optimized. FIG. 1 is a diagram illustrating an example of a configuration of a rolling system. FIG. 11 is a diagram showing an example of the change in the rolling state with respect to time when the tension and the preceding material running time in the steady state are optimized. FIG. 11 is a diagram showing an example of the timing for changing the rolling position of each rolling mill when optimizing tension and preceding material travel time in a steady state. FIG. 11 is a diagram showing an example of the timing for changing the roll speed of each rolling mill when optimizing tension and preceding material travel time in a steady state. 10 is a flowchart illustrating an example of a process for executing a running time setting change. FIG. 1 is a diagram illustrating the technology described in Patent Document 3.

First, for comparison with the embodiments of the present invention described later, the contents necessary for comparison with the embodiments of the present invention will be described with reference to FIG. 1, taking as an example a case in which a tandem rolling mill has five rolling mills. The number of rolling mills (N) provided in the tandem rolling mill is, for example, four or more (N≧4). The rolled material is not limited to steel material, and may be a metal material made of other metals, or may be composed of at least a portion of a material other than a metal material.

Figure 1 is a diagram showing an example of the change in rolling state over time. In Figure 1, the direction from left to right on the page is the transport direction of the material to be rolled in the tandem rolling mill. Of the five rolling mills shown in Figure 1, the rolling mill located most upstream (left side of the page) in the transport direction of the material to be rolled in the tandem rolling mill is the first rolling mill, and the rolling mills are the second, third, fourth, and fifth rolling mills moving downstream (right side of the page).

The leading end of the following material supplied to the tandem rolling mill is welded to the trailing end of the preceding material at welding point W, and then rolled in the order of the first rolling mill, the second rolling mill, the third rolling mill, the fourth rolling mill, and the fifth rolling mill.

Figure 1 shows the rolling state in each generation. In Figure 1, the top of the page is the first generation, which occurs earliest, and the generations are updated in the order of the second generation, third generation, fourth generation, fifth generation, and sixth generation. In this way, in Figure 1, time passes as the arrow on the vertical axis moves in the direction of the tip (downward). As mentioned above, the jth generation refers to the time period during which no running speed setting change is performed, from the end of the running speed setting change (change of the roll position and roll speed) performed when the welding point W passes through the j-1th rolling mill, to the start of the running speed setting change performed when the welding point W passes through the jth rolling mill, during which the steady state is in effect. Therefore, the rolling state in each generation shown in Figure 1 shows the rolling state when no running speed setting change is performed (when in a steady state).

The first generation is a state in which the welding point W is located upstream of the first rolling mill before the welding point W enters the first rolling mill. The second generation is a state in which the welding point W is located between the first and second rolling mills. The third generation is a state in which the welding point W is located between the second and third rolling mills. The same is true for the fourth and fifth generations. The sixth generation is a state in which the welding point W is located downstream of the fifth rolling mill.

The rolling mills of each generation are marked with a symbol such as h. These symbols will be explained below.
In the subscripts to the upper right of each symbol, the symbol with "I" indicates various setting values related to the preceding material, and the symbol with "II" indicates various setting values related to the following material.
The thickness setting value of the preceding material at the exit of the i-th rolling mill (i is an integer between 1 and 5) is defined as h _i ^I (where h ₀ ^I represents the thickness setting value at the entrance of the first rolling mill). In the following description, the range of the integer variable i is expressed as "i = 1 to 5", etc. The same notation is used for the integer variables j, k, etc. other than the variable i.
The tension setting value between the i-th rolling mill and the i+1-th rolling mill (i=1 to 4) of the preceding material is defined as T _i ^I (where T ₀ ^I represents the tension setting value at the inlet of the first rolling mill, and T ₅ ^I represents the tension setting value at the outlet of the fifth rolling mill).

In addition, the thickness setting value of the subsequent material at the exit of the ith rolling mill (i = 1 to 5) is denoted by h _i ^II (where h ₀ ^II represents the thickness setting value at the entrance of the first rolling mill), and the tension setting value of the subsequent material between the ith rolling mill and the (i+1)th rolling mill (j = 1 to 4) is denoted by T _i ^II (where T ₀ ^II represents the tension setting value at the entrance of the first rolling mill, and T ₅ ^II represents the tension setting value at the exit of the fifth rolling mill).

In the first generation, the entrance thickness H _i ⁽¹⁾ , exit thickness h _i ⁽¹⁾ , and tension T _i ⁽¹⁾ of all rolling mills are set to the preceding material's set values h _(i-1) ^I , h _i ^I , and T _i ^I , respectively. In the sixth generation, the entrance thickness H _i ⁽⁶⁾ , exit thickness h _i ⁽⁶⁾ , and tension T _i ⁽⁶⁾ of all rolling mills are set to the succeeding material's set values h _(i-1) ^II , h _i ^II , and T _i ^II , respectively.

The thickness of each rolled material in the jth generation (j=2 to 5) between the first and sixth generations will be described. First, the entrance thickness H _i ^(j) of the ith rolling mill (i=j to 5) located downstream of the welding point W is the thickness setting value h _(i-1) ^I of the preceding material, and the exit thickness h _i ^(j) is the thickness setting value h _i ^I of the preceding material. Also, the entrance thickness H _i ^(j) and the exit thickness h _i (j) of the ith rolling mill (i=1 to j-1) located upstream of the welding point W are the thickness setting values h _(i-1) ^{II and} h _i ^II of the succeeding material, respectively.

Next, the tension of each rolled material in the jth generation (j=2 to 5) between the first and sixth generations will be described. First, the preceding material is rolled between the ith rolling mill and the i+1th rolling mill (i=j to 4) located downstream of the welding point W and at the exit side of the fifth rolling mill. Therefore, the tension T _i ^(j) (i=j to 4) of the rolled material between the ith rolling mill and the i+1th rolling mill located downstream of the welding point W and the exit tension T ₅ ^(j) of the fifth rolling mill are the tension set values T _i ^I and T ₅ ^I of the preceding material, respectively. The succeeding material is rolled between the ith rolling mill and the i+1th rolling mill (i=1 to j-2) located upstream of the welding point W and at the entry side of the first rolling mill. Therefore, the tension T _i ^(j) (i = 1 to j-2) of the rolled material between the i-th rolling mill and the i+1-th rolling mill located upstream of the welding point W, and the inlet tension T ₀ ^(j) of the first rolling mill are the set values T _i ^II and T ₀ ^II of the following material, respectively.

The influence of the tension T _j-1 ^(j) of each rolled material between the j-1 rolling mill where the welding point W is present and the j-th rolling mill is greater in the rolling of the j-th rolling mill where the preceding material is rolled with the tension set value as the inlet tension of the j-th rolling mill than in the rolling of the j-1 rolling mill where the succeeding material is rolled with the tension set value as the outlet tension of the j-1 rolling mill. For this reason, in this embodiment, similar to Patent Document 1, the tension T j-1 ^(j) of each rolled material between the j-1 rolling mill where the welding point W is present and the j-th rolling mill is set to the tension set value T j _{- 1} ^I of the preceding material. Therefore, with regard to tension, when the welding point W passes through the j-th rolling mill between the j generation and the j+1 generation, the tension set value of each rolled material between the j-1 rolling mill and the j-th rolling mill is changed from the tension set value T _j-1 ^I of the preceding material to the tension set value T _j-1 ^II of the succeeding material. The tension of each rolled material between the rolling mills is common (the tension of the multiple rolled materials between the rolling mills is the same).

To summarize the settings of plate thickness, etc. in the tandem rolling mills described above, the inlet plate thickness H _{i (j), outlet plate thickness h i} ^(j) , and tension T _i ^(j) of each rolled material between the i-th rolling mill and the (i+1)-th rolling mill of the j-th generation (j = 1 to 6, _{i =} 1 ^{to 5)} are expressed by the following equations (1), (2), and (3), respectively (where T ₀ ^(j) represents the inlet tension of the first rolling mill, and T ₅ ^(j) represents the tension of each rolled material at the outlet of the fifth rolling mill).

Next, the rolling load and forward ratio of each rolling mill of each generation are calculated based on the above plate thickness and tension. In the first generation, the plate thickness and tension are all set values for the preceding material, so the rolling load P _i ⁽¹⁾ of the i-th rolling mill (i = 1 to 5) coincides with the rolling load set value P _i ^I of the preceding material, and the forward ratio f _i ⁽¹⁾ coincides with the forward ratio set value f _i ^I of the preceding material. In the sixth generation, the plate thickness and tension are all set values for the succeeding material, so the rolling load P _i ⁽⁶⁾ of the i-th rolling mill (i = 1 to 5) coincides with the rolling load set value P _i ^II of the succeeding material, and the forward ratio f _i ⁽⁶⁾ coincides with the forward ratio set value f _i ^II of the succeeding material.

In the jth generation (j=2 to 5) between the first and sixth generations, the entrance thickness, exit thickness, entrance tension, and exit tension in the i-th rolling mill (i=j to 5) located downstream of the welding point W are the set values for the preceding material. Therefore, the rolling load P _i ^(j) coincides with the rolling load set value P _i ^I of the preceding material, and the forward slip f _i ^(j) coincides with the forward slip set value f _i ^I of the preceding material.

In FIG. 1, the entrance thickness, exit thickness, entrance tension, and exit tension in the i-th rolling mill (i=1 to j-2) located two or more upstream of the welding point W are set to the set values of the following material. Therefore, the rolling load P _i ^(j) coincides with the rolling load set value P _i ^II of the following material, and the forward ratio f _i ^(j) coincides with the forward ratio set value f _i ^II of the following material. In the j-1-th rolling mill located one upstream of the welding point W, the entrance thickness, exit thickness, and entrance tension are set to the set values of the following material, but the exit tension is the set value of the preceding material. Therefore, the rolling load P _j-1 ^(j) and the forward ratio f _j-1 ^(j) do not coincide with the set values of either the preceding material or the following material. In FIG. 1, the rolling load P _j-1 ^(j) is represented as P _j-1 ^Z , and the forward ratio f _j-1 ^(j) is represented as f _j-1 ^Z.
To summarize the settings of the rolling loads and the like in the tandem rolling mills described above, the rolling load P _i ^(j) and the forward slip f _i ^(j) of the ith rolling mill of the jth generation (j = 1 to 6, i = 1 to 5) are given by the following equations (4) and (5), respectively.

1, for the first to fifth rolling mills, the rolling mills (rolls) for which the rolling load P _i ^(j) and forward forward ratio f _i ^(j) are the set values for the preceding material are shown by solid lines, the rolling mills (rolls) for which the set values for the succeeding material are shown by dashed lines, and the rolling mills (rolls) for which the set values for the preceding material dot and dash lines do not match the set values for either the preceding material or the succeeding material are shown by dashed lines. Furthermore, the preceding material is shown by a gray line (light density line), and the succeeding material is shown by a black line (dark density line).

The reduction position S _i ^(j) and roll speed v i (j) of the ith rolling mill of the jth generation (j = 1 to 6, i = 1 to 5) for achieving the rolling states expressed by equations ( ₁ ) to ⁽⁵⁾ can be obtained as follows.
First, the rolling position is determined from the exit thickness h _i ^(j) and the rolling load P _i ^(j) by the following formula (6) using a known gauge meter formula.

As shown in formula (6), when at least one of the exit thickness h _i ^(j) and the rolling load P _i ^(j) changes, the reduction position S _i ^(j) changes. Therefore, when formulas (2) and (4) are taken into consideration, it can be seen that the following formulas (7) to (11) hold.

Equation (7) is an equation related to the inter-generational roll position S ₁ ^(j) of the first rolling mill. Similarly, equations (8) to (11) are equations related to the inter-generational roll positions S _i ^(j) (i=2 to 5) of the second to fifth rolling mills.

Figure 2 shows the timing for changing the roll position for each rolling mill. In Figure 2, the timing for changing the roll position is indicated by curved arrows. When the welding point W passes through the first rolling mill (when moving from the first generation to the second generation), the roll position of the first rolling mill is changed. When the welding point W passes through the kth rolling mill (k = 2 to 5), the roll positions of the k-1th rolling mill and the kth rolling mill are changed.

Here, changing the roll position of each rolling mill when the welding point W passes through the ith rolling mill (i = 1 to 5) means that when each rolling mill changes its roll position, the welding point W passes through the gap between a pair of work rolls of the ith rolling mill between the start and end of the change in roll position. In other words, this means that the time when the welding point W passes through the gap between the pair of work rolls of the ith rolling mill is after the time when each rolling mill starts changing its roll position and before the time when the change in roll position is finished.

The roll speed is determined for each generation so that the following equation (12), which is the constant mass flow law for the following material upstream of the welding point W, and the following equations (13) and (14), which are the constant mass flow laws for the preceding material downstream of the welding point W, hold true.

Since equations (12) to (14) only stipulate the ratio of roll speeds between rolling mills in each generation, there are an infinite number of roll speeds that satisfy equations (12) to (14). Therefore, the fifth rolling mill, which is the most downstream rolling mill, is considered as a pivot rolling mill, and the following equation (15) is taken into consideration to match the roll speeds of the fifth rolling mill of each generation. A pivot rolling mill is a rolling mill whose roll speed does not change regardless of the passage of time, and is the rolling mill that serves as the standard for roll speed.

From equations (1), (2), (5), and (12) to (15), the roll velocities v _i ^(j) (j=1 to 6, i=1 to 5) can be obtained as shown in Table 1 below.

Therefore, when the fifth rolling mill is used as a pivot rolling mill, the timing for changing the roll speeds of the first to fifth rolling mills is as shown in FIG. 3. In FIG. 3, the timing for changing the roll speeds is indicated by curved arrows. When the welding point W passes through the kth rolling mill (k=1 to 4), the roll speeds of the first to kth rolling mills are changed, and when the welding point W passes through the fifth rolling mill, the roll speeds of the first to fourth rolling mills are changed.

Here, changing the roll speed of each rolling mill when the welding point W passes through the ith rolling mill (i = 1 to 5) means that when each rolling mill changes its roll speed, the welding point W passes through the gap between a pair of work rolls of the ith rolling mill between the start and end of the roll speed change. In other words, this means that the welding point W passes through the gap between the pair of work rolls of the ith rolling mill after each rolling mill starts changing its roll speed and before the end of the roll speed change.

The change in the roll position and roll speed between generations is generally done in a ramp-like manner (so that the rate of change is constant). The running change time, which is the time required to change the roll position and roll speed, is determined according to the response of the roll device and the rolling mill motor. The running change time and the preceding material running change time between generations are made equal regardless of the rolling mill so that the rolling part rolled by the rolling mill due to the change made when the welding point W passes through each rolling mill is the same for all rolling mills. In other words, the running change time and the preceding material running change time are the same regardless of which rolling mill is changed between any generations. As mentioned above, the preceding material running change time is the time from when the running setting change is started to when the welding point W reaches the rolling mill.

As described above, the reduction position S _i ^(j) and the roll speed v i ^(j) are derived so as to achieve the rolling state represented by the entrance thickness H _i ^(j) , the exit thickness h _i (j), the tension T _i (j) of each rolled material between the i-th rolling mill and the i+1-th rolling mill, the rolling load P _i ^{(j )} , and the forward forward ratio _{f i} ^{( j)} . Then, the running distance setting change is executed based on the reduction position S _i ^(j) and the roll speed v _i ^(j) derived in this way. In the embodiment of the present invention described below, when executing such a running distance setting change, the tension T _j-1 ^{(j) of each rolled material between the j-1-th rolling mill and the j-th rolling mill, where a welding point exists in the j-th generation (j = 2 to 5)} , and the timing of switching before and after the welding point W reaches the j-th rolling mill are simultaneously optimized, thereby suppressing the tension of each rolled material from becoming too high or too low when the running distance setting change is executed.

(Embodiment)
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In addition, the term "compared objects" including length, position, size, spacing, etc., being the same includes not only objects that are strictly the same, but also objects that are different within the scope of the invention (for example, objects that differ within the tolerance range determined at the time of design).

<Overview of the rolling system>
FIG. 4 is a diagram illustrating an example of a configuration of a rolling system.
In Fig. 4, the conveying direction of the preceding material M ^I and the following material M ^II is the positive direction of the X-axis. The preceding material M ^I and the following material M II are supplied to a tandem rolling mill having a first rolling mill 1 to a fifth rolling mill 5 in a state in which the rear end portion (the end portion on the negative side of the X-axis) of the preceding material M ^I and the front end portion (the end portion on the positive side of the X-axis) of the following material M II are welded at a welding point W. In this manner, in this embodiment, a case will be described as an example in which the rear end portion of the preceding material M ^I and the front end portion of the following material M ^II are joined by welding such as butt welding. The tandem rolling mill is disposed, for example, in a production line for cold-rolled steel sheets.

A first rolling mill 1, ^a second rolling mill ² , a third rolling mill, a fourth rolling mill, and a fifth rolling mill are arranged at equal pitches in this order from the upstream side (negative direction of the X-axis) to the downstream side (positive direction of the X-axis) in the transport direction of the preceding material M I and the following material M II. Note that the number (N) of rolling mills provided in the tandem rolling mill is not limited to five, and may be four or more, and may be four or six or more.

The first rolling mill 1 to the fifth rolling mill have reduction devices 1a to 5a and speed control devices 1b to 5b, respectively. The reduction devices 1a to 5a control the reduction positions of the rolling mills to which the reduction devices belong. The speed control devices 1b to 5b control the roll speeds (the rotational speeds of the work rolls that come into contact with the rolled material M ^I or M ^II ) of the rolling mills to which the speed control devices belong.
A plurality of strip speed meters 1c to 5c capable of measuring the speed of the strip (strip speed) are installed on the inlet side of each of the first rolling mill 1 to the fifth rolling mill 5. The strip speed meters 1c to 5c measure the strip speed (conveyance speed) of the preceding strip M ^I or the following strip M ^II at the installation position of each strip speed meter 1c to 5c, and output the measured strip speed to a tracking device 10.

The setting calculator 30 calculates the amount of change in the reduction position, the amount of change in the roll speed, the travel change time, and the preceding material travel change time for each of the first rolling mill 1 to the fifth rolling mill 5 when the welding point W passes through the kth rolling mill k (k = 1 to 5). The setting calculator 30 outputs the amount of change in the reduction position, the amount of change in the roll speed, and the travel change time to the travel setting change control device 20. The setting calculator 30 also outputs the preceding material travel change time to the tracking device 10.

The tracking device 10 tracks the position of the welding point W based on the plate speeds provided by the plate speed meters 1c to 5c, and outputs a command to start changing the rolling position and roll speed of the i-th rolling mill (i = 1 to 5) when the welding point W passes through the k-th rolling mill k, at a timing described below, to the running distance setting change control device 20.

The running setting change control device 20 outputs a roll position change command to the roll devices 1a to 5a and a roll speed change command to the speed control devices 1b to 5b based on the roll position and roll speed change start command given by the tracking device 10, and the roll position change amount, roll speed change amount, and running change time given by the setting calculator 30.

The roll reduction devices 1a to 5a control the roll reduction positions of the first rolling mill 1 to the fifth rolling mill 5 according to a roll reduction position change command given by the running speed setting change control device 20. The speed control devices 1b to 5b control the roll speeds of the first rolling mill 1 to the fifth rolling mill 5 according to a roll speed change command given by the running speed setting change control device 20. In this way, running speed setting change control is realized.

The hardware of the tracking device 10, the running time setting change control device 20, and the setting computer 30 is realized, for example, by using an information processing device having a CPU, ROM, RAM, HDD, and various interfaces, a programmable controller, or dedicated hardware. In addition, two or three of the tracking device 10, the running time setting change control device 20, and the setting computer 30 may be realized by a single device (hardware).

<Setting Calculator 30>
Before executing the running speed setting change from the preceding material M ^I to the succeeding material M ^II , the setting calculator 30 calculates the change amount ΔS _i ^[k] of the rolling position of the ith rolling mill i (i = 1 to 5) when the welding point W passes through the kth rolling mill k (k = 1 to 5), the change amount Δv _i ^[k] of the roll speed of the ith rolling mill i (i = 1 to 5) when the welding point W passes through the kth rolling mill k (k = 1 to 5), the running change time τ, and the running change time τ ^I of the preceding material (an example of a first decision variable). An example of this calculation process will be described in detail. Here, [k] represents the kth rolling mill k (k = 1 to 5) through which the welding point W passes when the running speed setting is changed, and i represents the ith rolling mill i (i = 1 to 5) to be calculated. Therefore, k takes one value (1, 2, 3, 4, or 5) for each running length setting change made between generations, while i takes five values (1, 2, 3, 4, and 5) for each generation. In the following description, the change amount ΔS _i ^[k] of the roll position of the ith rolling mill i (i = 1 to 5) when the welding point W passes through the kth rolling mill k (k = 1 to 5) is simply abbreviated as the change amount ΔS _i ^[k] of the roll position. Also, the change amount Δv _i [k] of the roll speed of the ith rolling mill i (i = 1 to 5) when the welding point W passes through the kth rolling mill k (k = 1 to 5) is simply abbreviated as the change amount Δv _i ^{[ k]} of the roll speed.

<<Calculation of change amount ΔS _i ^[k] of rolling position and roll speed Δv _i ^[k] >>
In Patent Documents 1 to 3, in the jth generation (j=2 to 5), the tension T _j-1 ^(j) of each rolled material between the j-1th rolling mill where the welding point W is present and the jth rolling mill is fixed to the set value T _j-1 ^I of the tension of the preceding material or the set value T _j-1 ^II of the tension of the following material, etc. In contrast, in this embodiment, in order to further suppress tension fluctuations during a change in the running length setting when the preceding material running change time τ ^I is appropriately determined, the tension T _j-1 ^(j) of each rolled material between the j-1th rolling mill where the welding point W is present and the jth rolling mill in the jth generation (j=2 to 5) is expressed as in the following formula (16). That is, in the jth generation (j = 2 to 5), the tension T _j-1 ^(j) of each rolled material between the j-1th rolling mill and the jth rolling mill, where the welding point W is located, is expressed as a value that divides the set value T _j-1 ^I of the tension of the preceding material and the set value T _j-1 ^II of the tension of the following material internally.

A variable α representing the ratio (hereinafter, referred to as the internal division ratio) of the tension setting value T _j-1 ^I of the preceding material and the tension setting value T _j-1 ^II of the following material is set as one of the optimization parameters (an example of the second decision variable). In this embodiment, the tension T _j-1 ^(j) of each rolled material between the j-1th rolling mill and the jth rolling mill, where the welding point W exists in the jth generation (j=2 to 5), is set to be any value between the tension setting value T _j-1 ^I of the preceding material and the tension setting value T _j-1 ^II of the following material according to the internal division ratio α.

As described above, the jth generation refers to a steady state time period during which no change in the running speed setting is performed, from the end of the running speed setting change (change in the roll position and roll speed) performed when the welding point W passes through the j-1th rolling mill to the start of the running speed setting change performed when the welding point W passes through the jth rolling mill. Therefore, it can be said that the tension T _j-1 ^(j) of each rolled material between the j-1th rolling mill where the welding point W exists and the jth rolling mill in the jth generation (j = 2 to 5) is the tension of each rolled material between the j-1th rolling mill and the jth rolling mill in that time period. In this embodiment, the jth rolling mill through which the welding point W passes between the jth generation and the j+1th generation (j = 2 to 5) is an example of a target rolling mill.

Figure 5 shows an example of the change in rolling state over time when the internal division ratio α is set to a certain value. As with Figure 1, Figure 5 shows the first rolling mill, second rolling mill, third rolling mill, fourth rolling mill, and fifth rolling mill from the left in the horizontal direction. Also, from the top, the rolling states of the first, second, third, fourth, fifth, and sixth generations are shown.

1, the tension T _j-1 ^(j) of each rolled material between the j-1th rolling mill where the weld point W is present and the jth rolling mill is set to the tension setting value T _j-1 ^I of the preceding material. For this reason, in the embodiment shown in FIG 1, in the jth generation (j = 2 to 5), the j-1th rolling mill is the only rolling mill whose rolling load P _j-1 ^(j) and forward factor f _j-1 ^(j) do not match the setting values of either the preceding material or the succeeding material.

In contrast to this, in this embodiment, in the jth generation (j = 2 to 5), the tension T _j-1 ^(j) of each rolled material between the j-1th rolling mill, where the weld point W is present, and the jth rolling mill does not match the set value of the preceding material and the set value of the succeeding material unless the interior division ratio α is 0 or 1. For this reason, in this embodiment, unless the interior division ratio α is 0 or 1, in the jth generation (j = 2 to 5), the rolling mills whose rolling load P _j-1 ^(j) and forward ratio f _j-1 ^(j) do not match the set value of either the preceding material or the succeeding material are the j-1th rolling mill and the jth rolling mill.

5, in the jth generation (j=2 to 5) between the first and sixth generations, the entrance thickness, exit thickness, entrance tension, and exit tension in the ith rolling mill (i=j+1 to 5), which is two or more mills downstream of the welding point W, are set to the set values of the preceding material. Therefore, the rolling load P _i ^(j) matches the rolling load set value P _i ^I of the preceding material, and the forward slip f _i ^(j) matches the forward slip set value f _i ^I of the preceding material.

In addition, the entrance thickness, exit thickness, entrance tension, and exit tension in the i-th rolling mill (i=1 to j-2), which is located two or more mills upstream of the welding point W, are set to the set values for the succeeding material. Therefore, the rolling load P _i ^(j) coincides with the rolling load set value P _i ^II of the succeeding material, and the forward slip f _i ^(j) coincides with the forward slip set value f _i ^II of the succeeding material.

5, the rolling load P _j-1 ^{(j) and forward forward ratio f j-1 (j)} of the j-1th rolling mill which do not match either the set value of the preceding material or the set value of the succeeding material in the jth generation (j = 2 to 5) are respectively represented as P j _{- 1} ^X and f _j-1 ^X. Also, the rolling load P _j ^(j) and forward forward ratio f j (j ⁾ of the jth rolling mill which do not match either the set value of the preceding material or the set value of the succeeding material in the jth generation ( _j = 2 to ⁵⁾ are respectively represented as P _j ^Y and f _j ^Y.

From the above, the entrance thickness H _i ^(j) and exit thickness h _i ^(j) of the ith rolling mill (i = 1 to 5) of the jth generation (j = 1 to 6) are respectively expressed by the above-mentioned formulas (1) and (2). Furthermore, the tension T _i ^(j) of each rolled material between the ith rolling mill of the jth generation and the (i+1)th rolling mill, the rolling load P _i ^(j) of the ith rolling mill of the jth generation, and the forward slip f _i ^(j) of the ith rolling mill of the jth generation are respectively expressed by the following formulas (17), (18), and (19).

In Fig. 5, the rolling mill (rolls) whose rolling load P _i ^(j) and forward forward ratio f _i ^(j) are the set values for the preceding material are shown by solid lines, and the rolling mill (rolls) whose rolling load P _i ^(j) and forward forward ratio f _i ^(j) are the set values for the succeeding material are shown by dashed lines. In addition, the j-1th rolling mill (rolls) whose rolling load P i (j) and forward forward ratio f i (j) are the set values for the preceding material and the succeeding material in the jth generation (j = 2 to 5) are shown by dashed lines, and the jth rolling mill (rolls) whose rolling load P i (j) and forward forward ratio f i (j) are the set values for the preceding material and the succeeding material in the jth generation (j = 2 to 5) are shown by dotted lines. In addition, the preceding material is shown by a gray line (light density line), and the succeeding material is shown by a black line (dark density line).

The reduction position S i (j) and roll speed v i (j) of the ith rolling mill (j = 1 to 6, i = 1 to 5) of the jth generation to achieve the rolling states expressed by the formulas (1), ₍ ^{2), (17), (} 18), and ₍ ¹⁹⁾ can be obtained as follows.
First, the rolling position can be calculated from the exit thickness h _i ^(j) and the rolling load P _i ^(j) using the known gauge meter equation (equation (6)). Taking into account equations (2) and (18), it can be seen that the following equations (20) to (24) hold.

Therefore, the change amount ΔS _i ^[k] of the rolling position of the ith rolling mill (i=1 to 5) when the welding point W passes through the kth rolling mill k (k=1 to 5) is expressed by the following formula (25).

However, from equations (20) to (25), ΔS _i ^[3] , ΔS _i ^[4] , ΔS _i ^[5] , ΔS ₂ ^[4] , ΔS ₂ ^[5] , ΔS ₃ ^[1] , ΔS ₃ ^[5] , ΔS ₄ ^[1] , ΔS ₄ ^[2] , ΔS ₅ ^[1] , ΔS ₅ ^[2] , and ΔS ₅ ^[3] are 0. Then, the timing for changing the roll position in the first rolling mill 1 to the fifth rolling mill 5 is as shown in Fig. 6. That is, when the welding point W passes through the first rolling mill 1, the roll position of the first rolling mill 1 and the roll position of the second rolling mill 2 are changed. When the welding point W passes through the kth rolling mill k (k=2 to 4), the rolling position of the k-1th rolling mill k-1, the rolling position of the kth rolling mill k, and the rolling position of the k+1th rolling mill k+1 are changed. When the welding point W passes through the fifth rolling mill 5, the rolling position of the fourth rolling mill 4 and the rolling position of the fifth rolling mill 5 are changed.

In addition, if the fifth rolling mill 5, which is the most downstream rolling mill, is a pivot rolling mill, the roll speed v _i ^(j) of the ith rolling mill (j = 1 to 6, i = 1 to 5) of the jth generation can be obtained from equations (1), (2), (12) to (15), and (19) as shown in Table 2 below.

Therefore, the change amount Δv _i ^[k] of the roll speed of the ith rolling mill (i=1 to 5) when the weld spot W passes through the kth rolling mill k (k=1 to 5) is expressed by the following equation (26).

However, from Table 2 and formula (26), Δv ₃ ^[1] , Δv ₄ ^[1] , Δv ₄ ^[2] , Δv ₅ ^[1] , Δv ₅ ^[2] , Δv ₅ ^[3] , Δv ₅ ^[4] , Δv ₅ ^[5] are 0. Then, the timing for changing the roll speeds of the first rolling mill 1 to the fifth rolling mill 5 when the fifth rolling mill is a pivot rolling mill is as shown in FIG. 7. That is, when the welding point W passes through the kth rolling mill k (k=1 to 3), the roll speeds of the first rolling mill 1 to the k+1th rolling mill k+1 are changed. When the welding point W passes through the fourth rolling mill 4 and when the welding point W passes through the fifth rolling mill 5, the roll speeds of the first rolling mill 1 to the fourth rolling mill 4 are changed.

The above changes in the roll position and roll speed are summarized for each rolling mill through which the welding point W passes. When the welding point W passes through the first rolling mill 1, the roll positions of the first rolling mill 1 and the second rolling mill 2 and the roll speeds of the first rolling mill 1 and the second rolling mill 2 are changed. When the welding point W passes through the kth rolling mill k (k=2, 3), the roll positions of the k-1st rolling mill k-1, the kth rolling mill k, and the k+1st rolling mill k+1 and the roll speeds of the first rolling mill 1 to the k+1st rolling mill k+1 are changed. When the welding point W passes through the fourth rolling mill 4, the roll positions of the third rolling mill 3, the fourth rolling mill 4, and the fifth rolling mill 5 and the roll speeds of the first rolling mill 1 to the fourth rolling mill 4 are changed. In addition, when the welding point W passes through the fifth rolling mill 5, the rolling positions of the fourth rolling mill 4 and the fifth rolling mill 5 and the roll speeds of the first rolling mill 1 to the fourth rolling mill 4 are changed.

Moreover, when the above is generalized to N rolling mills (N is an integer of 4 or more), the following is obtained.
That is, natural numbers are assigned to the N rolling mills in ascending order starting from the rolling mill located most upstream in the transport direction of the material to be rolled in the tandem rolling mill, and the N rolling mills are referred to as the first rolling mill to the Nth rolling mill, and an integer between 2 and N-1 is referred to as k. When the welding point W passes through the first rolling mill during the change in the running speed setting, the rolling positions of the first and second rolling mills and the roll speeds of the first and second rolling mills are changed, and when the welding point W passes through the kth rolling mill during the change in the running speed setting, the rolling positions of the first and second rolling mills and the roll speeds of the first and second rolling mills are changed. The rolling positions of the k-1 rolling mill, the kth rolling mill, and the k+1th rolling mill and the roll speeds of the first rolling mill to the k+1th rolling mill are changed, and if the welding point W passes the N-1th rolling mill when the running speed setting is changed, the rolling positions of the N-2th rolling mill, the N-1th rolling mill, and the Nth rolling mill and the roll speeds of the first rolling mill to the N-1th rolling mill are changed, and if the welding point W passes the Nth rolling mill when the running speed setting is changed, the rolling positions of the N-1th rolling mill and the Nth rolling mill and the roll speeds of the first rolling mill to the N-1th rolling mill are changed.

The contents of Tables 1 and 2 do not depend on the internal division ratio α shown in formula (16) (the ratio dividing the tension setting value T _j-1 ^I of the preceding strip and the tension setting value T _j-1 ^II of the succeeding strip). Therefore, the above-mentioned method of changing the reduction position and roll speed (when to change the reduction position and roll speed of which rolling mill) does not depend on the internal division ratio α shown in formula (16) and is the same regardless of the value of the internal division ratio α.

On the other hand, the rolling loads P _i ^(j) , P _i+1 ^(j) and forward forces f _i ^(j) , f i+1 ^(j) of the ith and ( _i+1 ) rolling mills of the jth generation depend on the tensions T _i ^(j) of the respective rolled materials between the ith and (i+1) rolling mills of the jth generation. Therefore, P _i ^X (i=1 to 4) and P _i ^Y (i=2 to 5) shown in formula (18) and f _i ^X (i=1 to 4) and f _i ^Y (i=2 to 5) shown in formula (19) depend on the interior division ratio α. Therefore, the change amount ΔS _i ^[k] of the roll position and the change amount Δv _i ^[k] of the roll speed change depending on the interior division ratio α.

That is, the rolling load P _i ^(j) and forward ratio f _i ^(j) are calculated according to the tension T _i ^(j) of each rolled material, and the roll position S _i ^(j) and roll speed v _i ^(j) are calculated according to the rolling load P _i ^(j) and forward ratio f _i ^(j) . Therefore, when the tension T _i ^(j) of each rolled material is calculated by the formula (17) by determining the interior division ratio α, the roll position S _i ^(j) and roll speed v _i ^(j) are calculated. Then, the roll position change amount _{ΔS i} ^[k] and the roll speed change amount Δv _i [k ^] are calculated by performing the calculations of the formulas (25) and (26) using the roll position S i ^(j) and the roll speed v i ( ^j) . Therefore, the roll position change amount _{ΔS i [} ^k] and the roll speed change amount Δv _i ^[k] change depending on the interior division ratio α.

In equations (18) and (19), P _i ^X and f _i ^X are respectively the rolling load and forward ratio of the i-th rolling mill (i=j-1) which do not match the set values of either the preceding or succeeding material in the j-th generation (j=2 to 5). _{P i} ^Y and f _i ^Y are respectively the rolling load and forward ratio of the i-th rolling mill (i=j) which do not match the set values of either the preceding or succeeding material in the j-th generation (j=2 to 5). These change depending on the interior division ratio α.

<<Calculation of travel time τ>>
The travel time τ is determined by the following equation (27) in accordance with the description of Patent Document 3, for example.

Here, τ _S,i ^[k] is the minimum time required for the reduction device ia of the i-th rolling mill i to change the reduction position by ΔS _i ^[k] . For example, τ _S,1 ^[k] is the minimum time required for the reduction device 1a of the first rolling mill 1 to change the reduction position by ΔS ₁ ^[k] . _{τ v,i} ^[k] is the minimum time required for the speed control device ib of the i-th rolling mill i to change the roll speed by Δv _i ^[k] . For example, τ _v,1 ^[k] is the minimum time required for the speed control device 1b of the first rolling mill 1 to change the roll speed by Δv ₁ ^[k] . In addition, in Patent Document 3, the running change time τ is referred to as the setting change time T.

<<Optimization calculation of internal division ratio α and preceding material travel time τ ^I >>
In this embodiment, the setting calculator 30 predicts a change in tension of the rolling material that occurs during a change in the running setting when the preceding material running time is τ ^I (0≦τ ^I ≦τ), where the preceding material running time τ ^I is one of the optimization parameters (an example of a first decision variable).

As an evaluation of the tension deviation, it is more appropriate to evaluate the tension stress obtained by dividing the tension by the cross-sectional area of each rolled material, rather than the tension itself. Therefore, in this embodiment, the setting calculator 30 predicts the entrance tension stress σ _b ^[k],I of the kth rolling mill k immediately before the welding point W arrives at the kth rolling mill k (k = 1 to 5), the exit tension stress σ _f ^[k],I of the kth rolling mill k immediately before the welding point W arrives at the kth rolling mill k (k = 1 to 5), the entrance tension stress σ _b ^[k],II of the kth rolling mill k immediately after the welding point W arrives at the kth rolling mill k (k = 1 to 5), and the exit tension stress σ _f ^[k],II of the kth rolling mill k immediately after the welding point W arrives at the kth rolling mill k (k = 1 to 5). Here, the entrance tension stress of the kth rolling mill k refers to the tension stress of each rolled material at the entrance of the kth rolling mill k. In addition, the exit tensile stress of the kth rolling mill k refers to the tensile stress of each rolled material at the exit of the kth rolling mill k. In the following description, the entrance tensile stress of the kth rolling mill k immediately before the welding point W arrives at the kth rolling mill k, the exit tensile stress of the kth rolling mill k immediately before the welding point W arrives at the kth rolling mill k, the entrance tensile stress of the kth rolling mill k immediately after the welding point W arrives at the kth rolling mill k, and the exit tensile stress of the kth rolling mill k immediately after the welding point W arrives at the kth rolling mill k will be simply referred to as the entrance tensile stress immediately before arrival at the rolling mill, the exit tensile stress immediately before arrival at the rolling mill, the entrance tensile stress immediately after arrival at the rolling mill, and the exit tensile stress immediately after arrival at the rolling mill, respectively.

As a calculation method for making these predictions, the method described in Patent Document 3 or a method called dynamic simulation (a method of dividing continuous time into minute time periods and sequentially calculating tension, outlet thickness, etc.) can be used. Patent Document 3 shows that the inlet tension stress σ _b [k],I just before arrival at the rolling mill, the outlet tension stress σ f ^[k],I just before arrival at the rolling mill, the inlet tension stress σ b [k] ^, II just after arrival at the rolling mill, and the outlet tension stress σ _f ^{[ k],II} _just after arrival at the rolling mill are calculated based on information on each rolled material (e.g., material, dimensions), the rolling position, and the roll _speed .

The setting calculator 30 obtains the optimal values of the optimization parameters (the internal division ratio α and the preceding strip travel time τ ^I ) that minimize the value of the evaluation function that numerically expresses the degree of the poorness of the tension change of each rolled strip that occurs during the travel setting change. In this embodiment, the value of the evaluation function is obtained by using the inlet tension stress σ _b ^[k],I just before the arrival at the rolling mill, the outlet tension stress σ _f ^[k],I just before the arrival at the rolling mill, the inlet tension stress σ _b ^[k],II just after the arrival at the rolling mill, and the outlet tension stress σ _f ^[k],II just after the arrival at the rolling mill. The setting calculator 30 outputs the change amount ΔS _i ^[k] of the roll position, the change amount Δv _i ^[k] of the roll speed, and the travel time τ used when obtaining the optimal values of the optimization parameters to the travel setting change control device 20. The setting calculator 30 also outputs the optimal value of the preceding strip travel time τ ^I to the tracking device 10. In addition, the internal division ratio α, the preceding material travel time τ ^I , the amount of change in the rolling position ΔS _i ^[k] , the amount of change in the roll speed Δv _i ^[k] , and the travel time τ are determined in the process of determining the entrance tensile stress σ _b ^[k],I just before reaching the rolling mill, the exit tensile stress σ _f ^[k],I just before reaching the rolling mill, the entrance tensile stress σ _b ^[k],II just after reaching the rolling mill, and the exit tensile stress σ _f ^[k],II just after reaching the rolling mill.

In order to obtain the optimal values of the optimization parameters, the setting calculator 30 may use a known Newton method or the like, which obtains the value of the evaluation function by giving appropriate initial values to the internal division ratio α and the preceding material travel time τ ^I , and corrects α and τ ^I so that the value of the evaluation function becomes smaller by using partial differential values of the evaluation function with respect to α and τ ^I.

A specific example of the evaluation function will be described below.
During the time period during which the preceding material M I is rolled from the start of the change in running speed setting (change in the roll gap position ΔS _i ^[k] and the roll speed Δv _i ^[k] ) when the welding point W passes through the kth rolling mill k (k = 1 to ⁵ ) to the arrival of the welding point W at the kth rolling mill k, the timing at which the rolling state becomes the furthest from the steady state before the start of the change in running speed setting is immediately before the welding point W arrives at the kth rolling mill k. Therefore, the timing at which the difference between the tension applied to the preceding material M ^I and the tension applied to the preceding material M ^I in the steady state before the start of the change in running speed setting becomes the largest is immediately before the welding point W arrives at the kth rolling mill k. Similarly, during the time period during which the succeeding material M II is rolled from the arrival of the welding point W at the kth rolling mill ^k to the end of the change in running speed setting (change in the amount of change in the roll gap position ΔS _i ^[k] and the amount of change in the roll speed Δv _i ^[k] ), the timing at which the rolling state becomes the furthest from the steady state after the end of the change in running speed setting is immediately after the welding point W arrives at the kth rolling mill k. Therefore, the timing at which the difference between the tension applied to the succeeding strip M ^II and the tension applied to the succeeding strip M ^II in the steady state after the completion of the change in the running length setting becomes maximum is immediately after the welding point W reaches the kth rolling mill k.

From the above, the degree of poorness of the tension change of each rolled material occurring during the change of the running speed setting can be evaluated by the deviation from the set value (target value) of the tension (predicted value) applied to the preceding material M ^I at a predetermined timing when the rear end (welding point W) of the preceding material M ^I reaches the kth rolling mill k (for example, as described above, this is the timing when the difference between the tension applied to the preceding material M ^I and the tension applied to the preceding material M ^I in the steady state before the start of the change of the running speed setting is maximized, such as immediately before the welding point W arrives at the kth rolling mill k or at the time of arrival), and the deviation from the set value (target value) of the tension (predicted value) applied to the following material M ^II at a predetermined timing when the front end (welding point W) of the following material M ^II reaches the kth rolling mill k (for example, as described above, this is the timing when the difference between the tension applied to the following material M ^II and the tension applied to the following material M ^II in the steady state after the end of the change of the running speed setting is maximized, such as immediately after the welding point W arrives at the kth rolling mill k or at the time of arrival).

As mentioned above, in order to evaluate the tension deviation, it is more appropriate to evaluate the tension stress obtained by dividing the tension by the cross-sectional area of each rolled material, rather than the tension itself. Therefore, the following equation (28), for example, can be used as the evaluation function J.

Equation (28) is an equation for finding the ^maximum value of the deviations for the set values (target values) σ _b ,k I , σ f,k I , σ _b , ^k II , and σ f,k ^{II of the entrance tensile stress and exit tensile stress of the kth rolling mill k applied to the preceding material M I} immediately before the welding point W reaches the kth rolling mill k (entrance tensile stress σ _b ^[k],I immediately before reaching the rolling mill and exit tensile stress σ f ^[k],I immediately before reaching the rolling mill) and the entrance tensile stress and exit tensile stress of the kth rolling mill k applied to the succeeding material M _II immediately after the welding point W reaches the ^kth rolling mill k ( ^entrance tensile stress σ _b ^[k], _II ^immediately _after reaching the rolling mill and exit tensile stress σ _{f [k} ], ^II immediately after reaching the rolling mill). In this embodiment, for example, each of the right-hand sides of equation (28) realizes an example of an evaluation index for evaluating the degree of tension change of the rolled materials (preceding material M ^I and succeeding material M ^II ) joined at the welding point W passing through the rolling mill that is the target of the running speed setting change when the running speed setting change is executed.

Here, σ _b,k ^I , σ _f,k ^I , σ _b,k ^II , and σ _f,k ^II are set values for the entrance tensile stress σ _b ^[k],I just before reaching the rolling mill, the exit tensile stress σ _f ^[k],I just before reaching the rolling mill, the entrance tensile stress σ _b ^[k],II just after reaching the rolling mill, and the exit tensile stress σ _f ^[k],II just after reaching the rolling mill, and can be calculated by the following equation (29).

where B ^I is the width of the preceding strip, and B ^II is the width of the succeeding strip. In addition, in formula (28), the entrance tension stress of the first rolling mill 1 and the exit tension stress of the fifth rolling mill 5, which do not correspond to the tension between the rolling mills, are excluded from the evaluation.

<Tracking device 10, running time setting change control device 20>
After the calculation and output of the setting calculator 30 is completed before executing the change in running length setting from the preceding material M ^I to the succeeding material M ^II , the change in running length setting is executed.
The tracking device 10 tracks the position of the welding point W based on the entry plate speed V _k of the kth rolling mill k (k=1 to 5) given by the plate speed meters 1c to 5c, and determines the distance from the welding point W to the kth rolling mill k based on the position of the welding point W and the position of the kth rolling mill k. The tracking device 10 compares the distance from the welding point W to the kth rolling mill k with the product (=V _k τ ^I ) of the preceding material travel time τ ^I given by the setting computer 30 and the entry plate speed V _k of the kth rolling mill k.

Then, when the tracking device 10 detects that the welding point W has reached a position V _k τ ^I upstream (on the negative side of the X-axis) from the kth rolling mill k (k = 1 to 5), it outputs a command to the running distance setting change control device 20 to start changing the reduction position and roll speed at the ith rolling mill i (i = 1 to 5) as the welding point W passes through the kth rolling mill k.

When a command to start changing the roll position and roll speed of the ith rolling mill i when the welding point W passes through the kth rolling mill k is given from the tracking device 10, the running setting change control device 20 uses the change amount ΔS i [k] of the roll position, the change amount Δv _i ^[k] of the roll speed, and the running change time τ of the ith rolling mill i (i = 1 to 5) when the welding point W passes through the kth rolling mill k given from the setting computer 30 to generate a roll position change command which is a command to change the roll position of the ith rolling mill i by ΔS _i ^{[ k] at a change rate ΔS i [} _{k ]} ^/ τ, and outputs it to the roll position device ia of the ith rolling mill i. The running setting change control device 20 executes the generation and output of such a roll position change command for each of the cases where the variable i is 1, 2, 3, 4, and 5.

Similarly, the running speed setting change control device 20 uses the change amount Δv i [k] of the roll speed of the ith rolling mill i (i=1 to 5) when the weld point W passes through the kth rolling mill k given by _{the setting computer 30 and the running change time τ to generate a roll speed change command which is a command to change the roll speed of the ith rolling mill i by Δv i [k] at a change rate Δv i [} ^{k ]} _/ ^τ, and outputs the command to the speed control device ib of the ith rolling mill. The running speed setting change control device 20 executes the generation and output of such a roll speed change command for each of the cases where the variable i is 1, 2, 3, 4, and 5.

The roll reduction device ia of the i-th rolling mill i controls the roll reduction position of the i-th rolling mill i in accordance with a roll reduction position change command given from the running speed setting change control device 20. The speed control device ib of the i-th rolling mill i controls the roll speed of the i-th rolling mill i in accordance with a roll speed change command given from the running speed setting change control device 20.
In this embodiment, the running speed setting change control is realized in the above manner.

<Flowchart>
Next, an example of a process for changing the running speed setting will be described with reference to the flowchart of FIG.
First, in step S801, the setting computer 30 determines the optimal values of the optimization parameters (inner division ratio α and preceding material travel time τ ^I ) that minimize the value of the evaluation function that numerically represents the degree of poorness of tension change of each rolled material that occurs during the travel setting change. In this embodiment, the setting computer 30 determines the optimization parameters (inner division ratio α and preceding material travel time τ ^I ) that minimize the value of the evaluation function J of the formula (28). The setting computer 30 stores the preceding material travel time τ I , the change amount ΔS _i ^[k] of the reduction position, the change amount Δv _i ^{[k] of} the roll speed, and the travel time τ that were used when determining the optimal values of the optimization parameters (inner division ratio ^α and preceding material travel time τ I ).

Next, in step S802, the setting calculator 30 outputs to the running setting change control device 20 the change amount ΔS _i ^[k] of the roll position, the change amount Δv _i ^[k] of the roll speed, and the running change time τ used when determining the optimal values of the optimization parameters.
Next, in step S803, the setting computer 30 outputs the optimum value of the preceding material travel time τ ^I to the tracking device 10.

Next, in step S804, the tracking device 10 judges whether or not to start changing the running speed setting. Specifically, when the tracking device 10 detects that the welding point W has reached a position upstream of the kth rolling mill k (k=1 to 5) by V _k τ ^I , the tracking device 10 judges to start changing the running speed setting for the kth rolling mill k. If the result of the judgment in step S804 is that the running speed setting change is to be started (YES in step S804), the process of step S805 is executed. On the other hand, if the result of the judgment in step S804 is that the running speed setting change is not to be started (NO in step S804), the process of step S805 is omitted and the process of step S806 described later is executed.

When the process proceeds to step S805, the running distance setting change control device 20 generates a rolling position change command which is a command to change the rolling position of the ith rolling mill i (i=1 to 5) by ΔS _i ^{[k] at a change rate ΔS i [} _k ^] /τ, and outputs it to the rolling device ia of the ith rolling mill i. In addition, the running distance setting change control device 20 generates a roll speed change command which is a command to change the roll speed of the ith rolling mill i (i=1 to 5) by Δv _i ^[k] at a change rate Δv _i [ ^k] /τ, and outputs it to the speed control device ib of the ith rolling mill.

In step S806, the tracking device 10 determines whether or not to end the running speed setting change control. For example, the tracking device 10 determines to end the running speed setting change control when the running speed setting change is completed when the welded portion W passes through the fifth rolling mill 5, which is the last rolling mill to roll the welded portion W. If the result of the determination in step S806 is to end the running speed setting change control (YES in step S806), the processing according to the flowchart in FIG. 8 ends. On the other hand, if the result of the determination in step S806 is not to end the running speed setting change control (NO in step S806), the processing in step S804 is executed again.

<Summary>
As described above, in this embodiment, the setting calculator 30 derives the values of the first and second decision variables when the value of the evaluation function including the evaluation index determined using the first and second decision variables for evaluating the degree of tension change of the two rolled materials joined at the welding point W becomes maximum or minimum when the running speed setting change is executed. Here, the first decision variable is a variable for determining the timing when the welding point W reaches the kth rolling mill k. The second decision variable is a variable for determining the tension T j-1 (j) of the two rolled materials between the j-1th rolling mill and the ^jth rolling mill where the welding point W exists in the _jth generation at the start of the running speed setting change. Therefore, the tensions of each rolled material in the steady state before and after the running speed setting change can be determined so that the tension change of each rolled material when the running speed setting change is executed is suppressed more than when the tensions of each rolled material in the steady state before and after the running speed setting change is fixed. Therefore, it is possible to suppress the tension fluctuation of each rolling material (the preceding material and the succeeding material) during the change of the running speed setting in the tandem rolling mill.

In this embodiment, the second variable used is an internal division ratio α which represents the ratio used when determining the tensions of the two rolled materials between the kth rolling mill k and the k-1th rolling mill k-1 at the start of the change in the running speed setting when the welding point W passes through the kth rolling mill k by internally dividing the set value T _j-1 ^I of the tension of the preceding material and the set value T _j-1 ^II of the tension of the following material. Therefore, it is possible to prevent the tensions of the rolled materials in the steady state before and after the change in the running speed setting from significantly deviating from the set value of the tension of the preceding material and the set value of the tension of the following material.
In this embodiment, the interior division ratio α is set to the same value regardless of j, so that the load of the optimization calculation can be suppressed and the tension change of each rolled material when the running speed setting is changed can be kept within a practically acceptable range.

In addition, in this embodiment, the evaluation function J is a function based on the deviation from the respective set values (σ b,k ^I , σ f,k I , σ b,k II , σ _f ^{,k II} ) of the entrance tensile stress and exit tensile stress (entrance tensile stress σ _b ^[k],I immediately before arrival at the rolling mill and exit tensile stress σ f [k],I immediately before arrival at the rolling mill) applied to the preceding material M ^I immediately before the welding point W reaches the kth rolling mill k, and the entrance tensile stress and exit tensile stress (entrance tensile stress σ _b ^[k],II _immediately after arrival at the rolling mill and exit tensile stress σ _f ^{[k],II immediately after arrival at} _the ^rolling _mill ^{) applied} to the succeeding material _M ^II immediately after the welding point W reaches the kth rolling mill k. Therefore, the tension change of each rolled material when the running speed setting change is being executed can be appropriately evaluated based on the deviation from the set value of the tension stress.

In this embodiment, the preceding material travel time τ ^I is used as the first decision variable. Therefore, the product (=V _k τ ^I ) of the preceding material travel time τ ^I obtained as a result of the optimization calculation and the inlet strip speed V _k of the kth rolling mill k is compared with the position of the welding point W, thereby making it possible to detect the start timing of the running speed setting change. Therefore, the calculation load for detecting the start timing of the running speed setting change can be reduced.

In addition, in this embodiment, natural numbers are assigned to the N rolling mills in ascending order starting from the rolling mill located most upstream in the transport direction of the material to be rolled in the tandem rolling mill, and the N rolling mills are referred to as the first rolling mill to the Nth rolling mill, and an integer between 2 and N-1 is referred to as k. When the welding point W passes through the first rolling mill when the running speed setting is changed, the rolling positions of the first and second rolling mills and the roll speeds of the first and second rolling mills are changed, and when the welding point W passes through the kth rolling mill when the running speed setting is changed, , the roll position of the k-1st rolling mill, the kth rolling mill, and the k+1st rolling mill and the roll speed of the 1st rolling mill to the k+1st rolling mill are changed, and when the welding point W passes through the N-1st rolling mill when the running speed setting is changed, the roll position of the N-2nd rolling mill, the N-1st rolling mill, and the Nth rolling mill and the roll speed of the 1st rolling mill to the N-1st rolling mill are changed, and when the welding point W passes through the Nth rolling mill when the running speed setting is changed, the roll position of the N-1st rolling mill and the Nth rolling mill and the roll speed of the 1st rolling mill to the N-1st rolling mill are changed. Therefore, compared to the case described in the (Prerequisite) section, by increasing the number of rolling mills that change the roll position and roll speed in the same generation, it is possible to suppress tension fluctuations in each rolled material during the running speed setting change in the tandem rolling mills (see Figures 2 and 6, Figures 3 and 7).

<Modification>
In this embodiment, the case where the evaluation function J in the formula (28) is used has been described as an example. However, if an evaluation index determined by using the first decision variable and the second decision variable is used as an evaluation index for evaluating the degree of tension change of each rolled material when the running speed setting change is being executed, the evaluation function J is not limited to the formula (28).

For example, the evaluation function J may be set taking into consideration that the greater the deformation resistance of the material being rolled, the more tension change is tolerable. For example, the evaluation function J in the following equation (30) may be used, in which the absolute values of the amount of change from the set value of the tension stress at each position of each rolled material (each of the right-hand sides of equation (28)) are weighted by the reciprocal of the deformation resistance at each position of each rolled material.

Here, K _b,k ^I is the inlet deformation resistance of the kth rolling mill k of the preceding material M ^I. K _f,k ^I is the outlet deformation resistance of the kth rolling mill k of the preceding material M ^I. K _b,k ^II is the inlet deformation resistance of the kth rolling mill k of the following material M ^II . _{K f,k} ^II is the outlet deformation resistance of the kth rolling mill k of the following material M ^II . The inlet deformation resistance of the kth rolling mill k refers to the deformation resistance of each rolled material at the inlet of the kth rolling mill k. In addition, the outlet tensile stress of the kth rolling mill k refers to the deformation resistance of each rolled material at the outlet of the kth rolling mill k. The inlet deformation resistance and the outlet deformation resistance of the kth rolling mill k are used for calculations of the forward ratio and the rolling load, and are obtained prior to the calculation of the forward ratio and the rolling load.

In addition, upper and lower limits may be set for each term in equation (28) or (30), and evaluation function J may be minimized within a range that satisfies the upper and lower limits. Alternatively, the value of evaluation function J may be maximized. In this case, for example, the entire right-hand side of equations (28) and (30) may be multiplied by -1 to use as evaluation function J.

In this embodiment, as shown in formula (16), an example has been described in which the interior division ratio α, which determines the tension between the j-1th rolling mill and the jth rolling mill where the weld point W is present in the jth generation (j=2 to 5), is set to the same value regardless of j. However, the following formula (31) may be used instead of formula (16). That is, as another example of the second decision variable, an interior division ratio α _j that can take an individual value for each section between the rolling mills where the weld point is present may be used. In this case, N-1 interior division ratios α _j (j=2 to N) and the preceding material travel time τ ^I are included in the optimization parameters.

However, in this case, the number of optimization parameters increases from 2 to N, so the calculation time becomes longer, and it may be difficult to find the optimal value within the time of about several seconds allowed for online calculation. When the tension stress setting value is the same, the tension setting value for each rolled material is proportional to the cross-sectional area of each rolled material, the plate width at each rolling mill is the same, and the outlet plate thickness gradually decreases from the first rolling mill to the N-1st rolling mill. Therefore, the magnitude relationship of the N-1 values of the tension setting values T ₁ ^I , ..., T _N-1 ^I of the preceding material between the j-1st rolling mill where the welding point W exists and the jth rolling mill in the jth generation is similar to the magnitude relationship of the N-1 values of the tension setting values T ₁ ^II , ..., T _N-1 ^II of the succeeding material. Therefore, mathematically, the value of the evaluation function when α _j (j=2 to N) and τ ^I are optimized under the formula (31) is always smaller than the value of the evaluation function when α and τ ^I are optimized under the formula (16), but the difference is considered to be large in many cases. In addition, as the number of optimization parameters increases, there is a risk that the optimal value cannot be obtained well within the allowed time, and a suboptimal value during optimization is adopted. For these reasons, it is preferable to set the interior division ratio α to the same value regardless of the rolling mills where the welding point W is present, as in the formula (16). However, when the performance of the computer is excellent or the number of rolling mills constituting the tandem rolling mill is small, etc., the interior division ratio α j may be obtained for each rolling mill where the welding point W is present, as in the formula (31), in order to obtain an optimal solution of the optimization parameters that reduces the value of the evaluation function _J. Furthermore, the second decision variable is not limited to the internal division ratios α and αj, so long as it is a variable for determining the tension T _j-1 ^(j) of the rolled material between the j-1th rolling mill and the jth rolling mill at which the welding point W is present in the jth generation. For example, the second decision variable may be an external division ratio representing the ratio when determining the tensions of the two rolled materials between the kth rolling mill k and _the k-1th rolling mill k-1 at the start of the change in the running speed setting when the welding point W passes through the kth rolling mill k, by externally dividing the set value T _j-1 ^I of the tension of the preceding material and the set value T _j-1 ^II of the tension of the following material.

In the present embodiment, the preceding material travel time τ ^I is included in the optimization parameters as an example of the first decision variable. However, the first decision variable is not limited to the preceding material travel time τ I as long as it is an index used to determine the timing at which the welding point W reaches the kth rolling mill k between the start and end of the travel setting change (i.e., within the travel change time). For example, the following material travel time may be used as the optimization parameter instead of ^{the preceding material travel time τ I. The} following material travel time is the time from when the welding point W reaches the rolling mill to when the travel setting change is completed, and is obtained by subtracting the following material travel time from the travel change time.

In addition, in this embodiment, an example is given of a case where the running speed setting change is performed for all rolling mills (five rolling mills) owned by the tandem rolling mill. However, the target rolling mills, which are the rolling mills that are the targets of the running speed setting change, may include at least one of the multiple rolling mills owned by the tandem rolling mill.

<Calculation example>
Next, the results of a computer simulation of changing the running length setting by the method described in this embodiment will be described. In this calculation example, the width of the preceding strip was 950 mm, and the width of the succeeding strip was 1020 mm. The entrance thickness, exit thickness, tension setting value, and deformation resistance value are shown in Table 3 below.

Example 1 of the invention is a method in which the tension T _j-1 ^(j) of each rolled material between the j-1th rolling mill where the welding point W is located and the jth rolling mill in the jth generation (j = 2 to 5) is a function of the internal division ratio α as shown in equation (16), and the internal division ratio α, i.e., the tension T _j-1 ^(j) of each rolled material between the j-1th rolling mill where the welding point W is located and the jth rolling mill, and the running time τ ^I of the preceding material are determined so that the value of the evaluation function in equation (29) is minimized.

In addition, in the jth generation (j = 2 to 5), the tension T _j-1 ^(j) of each rolled material between the j-1th rolling mill where the welding point W is located and the jth rolling mill is defined as a function of the internal division ratio α _j (j = 2 to 5) as shown in equation (30), and a method is determined in which the internal division ratio α _j , i.e., the tension T _{j-1 (j)} of each rolled material between the j-1th rolling mill where the welding point W is located and the jth rolling mill, and the preceding material running time τ ^I are determined so that the value of the evaluation function in equation (29 ⁾ is minimized.

On the other hand, a method in which the preceding material travel time τ ^I is fixed to half the travel time τ (τ ^I =0.5τ) and only the tension T _j-1 ^(j) of each rolled material between the j-1th rolling mill where the weld point W is present and the jth rolling mill is determined as an optimization parameter is set as Comparative Example 1. In Comparative Example 1, similar to Invention Example 2, the tension T j-1 (j) of each rolled material between the _j-1th rolling mill where the weld point W is present and the jth rolling mill in the jth generation ⁽ j=2 to 5) is set as a function of the internal division ratio α _j (j=2 to 5) as shown in Equation (30). Comparative Example 1 corresponds to determining α _j so that the value of the evaluation function J in Equation (29) is minimized under the constraint of τ ^I =0.5τ.

Comparative Example 2 is a method in which the tension T _j-1 ^(j) of each rolled material between the j-1th rolling mill and the jth rolling mill where the welding point W is present is determined by fixing the set value of the tension of the preceding material between the j-1th rolling mill and the jth rolling mill to T _j-1 ^I , and determining only the preceding material travel time τ ^I as an optimization parameter. In Comparative Example 2, similar to Invention Example 1, the tension T _j-1 ^(j) of each rolled material between the j-1th rolling mill and the jth rolling mill where the welding point W is present in the jth generation (j = 2 to 5) is set as a function of the interior division ratio α as shown in Equation (16). Comparative Example 2 corresponds to determining τ ^I so that the value of the evaluation function J in Equation (29) is minimized under the constraint of α = 1. That is, Comparative Example 2 corresponds to the method of Patent Document 3.

The travel time τ, the internal division ratios α, α _j , the preceding material travel time τ ^I , and the evaluation function J in each case are shown in Table 4 below.

The value of the evaluation function J, which numerically represents the degree of poorness of tension change in each rolled material occurring during the running speed setting change, is reduced by about 50 to 60% in the invention examples 1 and 2 compared to the comparative examples 1 and 2. In this way, it can be seen that the tension fluctuation of each rolled material during the running speed setting change can be better controlled by appropriately determining both the tension T _j-1 ^(j) of each rolled material between the j-1th rolling mill where the welding point W is present and the ^jth rolling mill, and the preceding material running change time τ I.
Comparing Example 1 and Example 2, there is no large difference in the value of the evaluation function J. Therefore, it can be seen that Example 1, which has a small number of optimization parameters (2) and a low calculation load, is preferable from the practical viewpoint of finding an optimal value within a time of about several seconds allowed for online calculation.

(Other Modifications)
The above-described embodiment of the present invention can be realized by a computer executing a program. A computer-readable recording medium on which the program is recorded and a computer program product such as the program can also be applied as an embodiment of the present invention. Examples of the recording medium that can be used include a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a non-volatile memory card, and a ROM. The embodiment of the present invention can be realized by a PLC (Programmable Logic Controller) or dedicated hardware such as an ASIC (Application Specific Integrated Circuit).
Furthermore, the above-described embodiments of the present invention are merely examples of the implementation of the present invention, and the technical scope of the present invention should not be interpreted as being limited by these. In other words, the present invention can be implemented in various forms without departing from its technical concept or main features.

1 to 5: rolling mill, 1a to 5a: screw down device, 1b to 5b: speed control device, 1c to 5c: strip speed meter, 10: tracking device, 20: running setting change control device, 30: setting calculator, M ^I : preceding material, M ^II : succeeding material, W: welding point

Claims (10)

A processing device for executing a running speed setting change that changes a setting value of a target rolling mill when a joint that joins a plurality of rolled materials in a conveying order passes through the target rolling mill among tandem rolling mills,
a setting calculation means for determining a setting value of the target rolling mill based on an evaluation function for evaluating a degree of a tension change of the two rolled materials joined at the joint when the running speed setting change is executed for the target rolling mill,
the evaluation function includes an evaluation index determined using a first decision variable and a second decision variable;
The first decision variable is a variable for determining a timing at which the joint reaches the target rolling mill between a start and an end of the change in the running speed setting,
The second decision variable is a variable for determining tensions of the two rolled materials between the target rolling mill and a rolling mill one upstream of the target rolling mill at the start of a running speed setting change of the target rolling mill,
The setting calculation means is a processing device that determines the value of the first decision variable and the value of the second decision variable when the value of the evaluation function becomes a maximum value or a minimum value. The processing device according to claim 1, wherein the second decision variable is a variable representing a ratio when determining the tension of the two rolled materials at the start of the change in running speed setting by dividing the tension setting value of the preceding material, which is the rolled material downstream of the joint, and the tension setting value of the following material, which is the rolled material upstream of the joint. The processing device according to claim 2, wherein the value of the ratio is the same regardless of the target rolling mill. The processing device according to claim 2, wherein the ratio value is determined for each target rolling mill. The processing device according to any one of claims 1 to 4, wherein the evaluation function is a function based on the deviation of the tensile stress of the rolled material at the entrance and exit of the target rolling mill at a predetermined timing when the rear end of the preceding material, which is the rolled material downstream of the joint, reaches the target rolling mill, from the set value of the preceding material, and the deviation of the tensile stress of the rolled material at the entrance and exit of the target rolling mill at a predetermined timing when the front end of the following material, which is the rolled material upstream of the joint, reaches the target rolling mill, from the set value of the following material. The processing device according to any one of claims 1 to 5, wherein the first decision variable includes a preceding material run change time, which is the period from when the run setting change is started to when the joint reaches the target rolling mill. The processing device according to any one of claims 1 to 6, wherein the set values include the rolling position and roll speed of the rolling mill. When natural numbers are assigned to the N rolling mills constituting the tandem rolling mill in ascending order from the rolling mill located at the most upstream position in the conveying direction of the rolled material, the N rolling mills are referred to as the first rolling mill to the Nth rolling mill, and an integer of 2 or more and N-1 or less is referred to as k,
When the first rolling mill is the target rolling mill, the rolling positions of the first rolling mill and the second rolling mill and the roll speeds of the first rolling mill and the second rolling mill are changed,
When the kth rolling mill is the target rolling mill, the rolling positions of the k-1th rolling mill, the kth rolling mill, and the k+1th rolling mill and the roll speeds of the 1st rolling mill to the k+1th rolling mill are changed;
When the N-1 rolling mill is the target rolling mill, the rolling positions of the N-2 rolling mill, the N-1 rolling mill, and the N rolling mill and the roll speeds of the 1st rolling mill to the N-1st rolling mill are changed,
The processing device according to claim 7, wherein, when the Nth rolling mill is the target rolling mill, the rolling positions of the N-1th rolling mill and the Nth rolling mill and the roll speeds of the 1st rolling mill to the N-1th rolling mill are changed. A processing method for executing a running speed setting change in which a setting value of a target rolling mill is changed when a joint portion that joins a plurality of rolled materials in a conveying order passes through the target rolling mill among tandem rolling mills, comprising:
a setting calculation step of determining a setting value of the target rolling mill based on an evaluation function that evaluates a degree of tension change of the two rolled materials joined at the joint when the running speed setting change is executed for the target rolling mill,
the evaluation function includes an evaluation index determined using a first decision variable and a second decision variable;
The first decision variable is a variable for determining a timing at which the joint reaches the target rolling mill between a start and an end of the change in the running speed setting,
The second decision variable is a variable for determining tensions of the two rolled materials between the target rolling mill and a rolling mill one upstream of the target rolling mill at the start of a running speed setting change of the target rolling mill,
In the setting calculation step, a value of the first decision variable and a value of the second decision variable when the value of the evaluation function becomes a maximum value or a minimum value are determined. Computer,
A program for causing the setting calculation means according to any one of claims 1 to 8 to function as such.

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