JP2998550B2 - Pass schedule determination method for reversible rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining a pass schedule of a reversible rolling mill, and more particularly to an improvement in production efficiency.

[0002]

2. Description of the Related Art The method of determining a pass schedule in a reversible rolling mill can arbitrarily change the number of passes unlike a tandem rolling mill. Conventionally, the number of passes and the thickness schedule have been empirically determined. Therefore, when trying to reduce the number of passes as much as possible in order to increase the productivity, the rolling load becomes abnormally high, the plate shape is disturbed, and the mechanical device of the rolling mill is sometimes overloaded.
Conversely, when rolling is performed with a reduced rolling load so that the plate shape becomes good, there is a problem that the number of passes increases and the rolling efficiency decreases. Thus, when considering the rolling efficiency, the number of passes and the thickness schedule are very important.

On the other hand, as a method of determining a pass schedule in a reversible rolling mill, Japanese Patent Publication No.
There is a method proposed in Japanese Patent Publication No. In this method, the minimum number of passes is determined by sequentially calculating the exit plate thickness of each pass based on the allowable maximum load or the allowable maximum draft, and then redistributed so that the drafts of all the passes are equal. By doing so, the rolling reduction of each pass is determined. Here, the allowable maximum load is set from the upper limit load on the hardware characteristics of the rolling mill and the upper limit load at which the shape defect does not occur. The allowable maximum rolling reduction is set to the upper limit of the rolling reduction at which abnormal rolling such as chattering and slip does not occur. By setting such allowable maximum load and allowable maximum draft, it is possible to determine the draft of each pass that can avoid the occurrence of shape defects and the occurrence of abnormal rolling without applying a load overload to the rolling mill. it can.

[0004]

Generally, as mechanical constraints of a rolling mill, there are power constraints of a driving device of the rolling mill in addition to load constraints. However, in the method disclosed in the above publication, this point is not taken into consideration, and therefore, when rolling is performed based on the calculated pass schedule, a load exceeding the restricted range of the power of the driving device is applied to the rolling mill, and In some cases, rolling may not be performed according to the calculated pass schedule. Also, in general, abnormal rolling phenomena such as chattering and slipping are caused by friction conditions of a roll bite which differs depending on a rolled material or a surface roughness of a roll, a lubricating oil to be used, a tension balance on an inlet / outlet side of each pass, and the like. It is greatly affected by the rolling speed. But,
In the method of the above publication, only the rolling reduction is considered as a means for avoiding abnormal rolling, which is insufficient. Also,
The thickness of the sheet rolled by the reversible rolling mill is wide, and for example, in the case of a cold rolling mill, it ranges from 3 m to 0.5 mm. For this reason, since it is necessary to control a wide range of tension, a tension device attached to a reversible rolling mill generally has a gear device. Since the rolling speed is determined by the selection of the gear device, it is important to select an appropriate gear according to the plate thickness in consideration of production efficiency. However, the method of the above publication does not consider a method of selecting a gear of a tension device at all.

[0005] In a reversible rolling mill, the tension and rolling speed of each pass can be set freely within certain restrictions. Since the production efficiency and the stability of rolling are greatly affected by the setting of the tension and the rolling speed, it is necessary to determine the tension and the rolling speed in addition to the rolling reduction. However, in the method of the above publication, no consideration is given to a method of setting the rolling speed and the tension. In general, when considering the rolling efficiency, a method of maximizing the rolling reduction of each pass and minimizing the total number of passes and a method of increasing the rolling speed of each pass are considered. However, in the method of the above publication, only the former is considered, and setting of the rolling speed is not considered at all. Further, since the rolling efficiency of both materials changes depending on the base material plate thickness of the rolled material, the finished plate thickness, the coil length, the working time required for changing gears, etc., the method of the above publication is not necessarily the optimal pass schedule. Absent.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a method of determining a pass / schedule pass of a reversible rolling mill with high production efficiency.

[0007]

According to one aspect of the present invention, there is provided a method for determining a pass / schedule path of a reversible rolling mill according to one aspect of the present invention. In determining the pass schedule, the rolling speed is determined by maximizing the rolling reduction of each pass, with the upper limit of the allowable load, the base torque of the drive system of the rolling mill main body, and the lower limit of the allowable advanced rate being the limiting conditions. Is set to the maximum value that can be set in the rolling reduction, the tension is set based on a preset tension reference value, and subsequently, the gear of the tension device is adjusted according to the thickness and tension of each pass. Make the right choice,
The rolling speed and the tension are finally determined based on the selected upper limit of the speed and the tension of the gear of the tension device.

According to another aspect of the present invention, there is provided a method for determining a pass / schedule pass of a reversible rolling mill.
In determining the pass schedule when rolling a sheet using a reversible rolling mill, the upper limit of the allowable load, the upper limit of the torque determined by the upper limit of the power of the drive system of the rolling mill and the rolling speed, and the lower limit of the allowable advance rate With the value as a constraint, the rolling speed of each pass is set to the maximum speed of the rolling mill, the draft is determined accordingly, the tension is set based on a preset tension reference value, and subsequently, The gears of the tensioning device are appropriately selected according to the thickness and tension of each pass, and the rolling speed and the tension are finally determined based on the selected upper limit of the speed and tension of the gear of the selected tensioning device.

A method for determining a pass / schedule path of a reversible rolling mill according to still another aspect of the present invention (claim 3).
Calculates the pass schedule by the above-mentioned determination method (the inventions of claims 1 and 2), evaluates the index of the rolling efficiency, and adopts the pass schedule with the higher evaluation.

[0010]

According to one aspect of the present invention, the upper limit of the allowable load, the base torque of the rolling mill main body, and the lower limit of the allowable advanced rate are set as constraints, and the rolling reduction, rolling speed and rolling speed of each pass are determined. Determine the tension and at the same time set the gear of the tensioning device. Here, the allowable load upper limit as a criterion for determining the pass schedule is set by a limit such as a mechanical strength of a rolling mill or a constraint on a rolling operation, for example, a load upper limit that does not cause a shape defect. Things. The base torque is the maximum torque of the drive system of the rolling mill main body. The lower limit of the allowable advanced rate is the advanced rate at which abnormal rolling such as chattering does not occur. According to one aspect of the present invention, the rolling reduction is first set so as to satisfy the upper limit of the allowable load, and when the torque exceeds the upper limit, the torque is corrected by changing the tension balance and the rolling reduction. If the advance rate falls below the lower limit, the tension balance, rolling speed and rolling reduction are changed. These control factors are determined so that the rolling reduction is maximized, and the rolling speed is determined using the relationship between the upper power limit of the drive system of the rolling mill body, the torque, and the rolling speed using the rolling speed. Set the maximum speed that can be set when rolling at a rate. By this method, it is possible to avoid the load overload on the rolling mill, the power overload on the rolling mill, and the abnormal rolling and minimize the number of passes, and determine a pass schedule with high production efficiency. Becomes At the same time, by appropriately selecting the gear of the tension device, it is possible to set an appropriate tension and to set an appropriate rolling speed.

According to another aspect of the present invention, the upper limit of the allowable load, the upper limit of the power of the drive system of the rolling mill body,
The rolling reduction, rolling speed and tension of each pass are determined with the upper torque limit and the lower limit of the allowable advanced ratio determined from the relationship between the torque and the rolling speed as constraints, and at the same time the gear of the tension device is set. In the present invention, the rolling reduction is set so as to satisfy the allowable load upper limit, the tension balance and the rolling reduction are changed when the torque exceeds the upper limit, and the tension balance and the rolling reduction when the advanced ratio is lower than the allowable lower limit. Change the rolling reduction. These control factors are determined so that the rolling speed is maximized. By this method, it is possible to avoid a load overload on a rolling mill, a power overload on a rolling mill, and abnormal rolling and realize high-speed rolling, and determine a pass schedule with high production efficiency. Become. At the same time, by appropriately selecting the gear of the tension device, it is possible to set an appropriate tension and to set an appropriate rolling speed.

According to still another aspect of the present invention (claim 3), a pass schedule having the highest rolling efficiency among pass schedules determined by the above method can be determined.

[0013]

Next, a method for determining a path schedule according to an embodiment of the present invention will be described. First, the control conditions of the load, torque, and advance ratio for determining the pass schedule will be described. First, the following items can be considered as factors defining the upper limit of the allowable load. (1) The upper limit of the load determined from the problem of the strength of the mechanical device of the rolling mill body. (2) The upper limit of the load determined from the Hertz stress between rolls. (3) Operational load upper limit. This is a load upper limit value or the like that can avoid occurrence of a shape defect that exceeds the control capability of the shape control device installed in the rolling mill. Second, the torque upper limit is determined by rolling conditions such as the power upper limit of the drive motor of the rolling mill and the rolling speed. In general, the equation for predicting the rolling power has the following format. _{L = L (T q, R} , V R, H, h, t f, t b, f s, swd) ... (1) where, T _q: rolling torque, R: roll diameter, V _R: roll speed , H: entrance side plate thickness, h: exit side plate thickness, t _f : exit side tension, t _b : entrance side tension, f _s : advance ratio, swd: plate width. When this is solved for the rolling torque, the following function is obtained. _{T q = T q (L,} R, V R, H, h, t f, t b, f s, swd) ... (2)

In general, the relationship between the rotation speed of the motor and the torque is defined as follows:
In the voltage control range, the torque is a constant value (this is referred to as a base torque). Above that, the torque is in the field control range, and the torque decreases as the rotation speed of the motor increases. is there. Therefore, if the rolling speed exceeds the base speed, the torque upper limit value, the power upper limit value L _max and the rolling conditions of the drive motor (2) is given by the equation, if the rolling speed is below a base speed , The torque upper limit is set to the base torque.

Third, regarding the lower limit of the allowable advance rate, it is a known fact that the advance rate is generally an index indicating the stability of rolling. The lower limit of the allowable advance ratio is a limit value at which rolling instability phenomena such as stripping and chattering do not occur, and can be determined by a rolling experiment or a simulation based on rolling theory. FIG. 9 shows an example when an advanced rate limit value at which chattering does not occur is obtained in a rolling experiment. On the other hand, a number of formulas have been proposed for estimating the rolling load, the rolling torque, and the advanced ratio. The format is, P = P (H, h , μ, k, t f, t b, R, f s) ... (3) T q = T q (H, h, μ, k, t f, t b _{, R, f s) ... (} 4) f s = f s (H, h, μ, k, t f, t b, R) ... (5) where, P: rolling load, T _q: rolling torque, f _s : advanced rate, R: roll diameter, H: incoming plate thickness, h: outgoing plate thickness,
t _f: exit side tension, t _b: the entry side tension, μ: friction coefficient, k:
Average deformation resistance. These functions are generally implicit functions for the exit plate thickness. When calculating the outlet plate thickness based on the above constraints, a method using a computer,
For example, it can be calculated by the Newton method or the like.

Next, a method for determining the rolling speed, tension and rolling reduction of each pass, that is, the thickness of the delivery side plate will be described. In one embodiment of the present invention, when determining the rolling reduction of each pass, the input / output side tension, and the rolling speed, the above-described constraints are satisfied, and the rolling reduction of each pass is maximized. The rolling speed is determined to be the maximum value that can be set from the relationship between the upper limit of the power of the drive system of the rolling mill body, the torque, and the rolling speed. In another embodiment of the present invention, the rolling speed is determined to be the maximum. Here, the former is called a minimum pass mode, and the latter is called a high-speed rolling mode.

FIGS. 1 to 3 are flowcharts showing a method of determining rolling conditions for each pass in the present invention. In the calculation method shown in this flowchart, the basic processing procedure in both calculation modes is the same. At first,
The exit side thickness is determined with the allowable load upper limit as a constraint. Next, it is checked whether the torque and the advance rate satisfy the constraint. Here, when the torque and the advance rate do not satisfy the respective constraint conditions, the rolling reduction, the tension balance and the rolling speed of each pass are changed so that the load, the torque and the advance rate satisfy the constraint conditions. The difference between the two calculation modes will be described later for each of the following calculation steps.

(Step 1) This is an initial setting section,
The thickness of the incoming side, rolling speed, incoming side tension, outgoing side tension of each pass, each constraint (upper allowable load, upper torque, upper allowable advanced rate) and pass schedule calculation mode (high speed rolling mode or minimum pass mode) Set. Here, the initial setting value of the rolling speed is the base speed of the drive system of the rolling mill main body in the case of the minimum pass mode, and the maximum rolling speed that can be set in the rolling mill in the case of the high speed rolling mode. The initial set value of the torque upper limit is the base torque of the drive system of the rolling mill main body in the case of the minimum pass mode, and is given by Expression (2) in the case of the high speed rolling mode. In addition, the magnitudes of the input side tension and the output side tension are set so as to increase stepwise each time the path is followed, in order to prevent damage caused by tight tightening in the coil winding device. Is determined in consideration of the magnitude of the deformation resistance of the rolled material. The entrance side plate thickness is set to the exit side plate thickness obtained by the calculation of the previous pass.

(Step 2) Next, when the rolling load is set to the allowable load upper limit, the exit side plate thickness is calculated by Newton's method using equation (3). At this time, if the calculated outlet plate thickness is smaller than the finished plate thickness, the outlet plate thickness is set to the finished plate thickness. At the same time, an estimated torque value is calculated by equation (4) and an advanced rate estimated value is calculated by equation (5). Here, when the torque constraint condition and the advanced rate constraint condition are not satisfied, rolling cannot be actually performed. Next, it is determined whether the torque and the advance ratio calculated above satisfy the respective constraint conditions.

(Step 3) First, it is determined whether or not the calculated estimated torque value is equal to or less than the torque upper limit value. Here, a calculation procedure when the estimated torque value exceeds the upper limit value will be described. Control factors for the rolling torque include (1) tension balance and (2) rolling reduction. First, change the balance between the incoming and outgoing tensions within the allowable range,
The torque estimated value and the advanced rate estimated value are calculated by the equations (4) and (5). When the estimated torque value falls below the upper limit value, the process proceeds to the next step. If the estimated torque value is still higher than the upper limit value and the estimated torque value is equal to or less than the base torque, the output side plate thickness when the estimated torque value is set to the upper torque value is calculated by using equation (4). Calculate by the Newton method and determine the draft. If the estimated torque value exceeds the base torque, the exit plate thickness when the base torque is set to the torque upper limit value is calculated by Newton's method using equation (4) to determine the rolling reduction. At this time, if the calculated outlet plate thickness is smaller than the finished plate thickness, the outlet plate thickness is set to the finished plate thickness. Further, a rolling load estimated value is calculated by the equation (3), and an advanced rate estimated value is calculated by the equation (5). By the above processing, a rolling reduction, a rolling speed, and a tension satisfying the load constraint condition and the torque constraint condition can be obtained.

In the case of the high-speed rolling mode, the process proceeds to the next step. In the case of the minimum pass mode, the highest possible rolling speed is determined within the range of the obtained rolling conditions based on the relationship between the upper limit of the power of the driving system of the rolling mill, the torque, and the rolling speed. Here, when equation (1) is solved for the rolling speed, equation (6) is obtained. V _R = V _R (L, T _q , R, H, h, t _f , t _b , f _s , swd) (6) In equation (6), L represents the power upper limit L _max , and other parameters Is substituted for the set value obtained by the above calculation, and the highest possible rolling speed is determined.

(Step 4) It is determined whether or not the estimated value of the advanced rate calculated in the previous step is equal to or more than the lower limit of the allowable advanced rate, and if satisfied, the process proceeds to the next step. Here, a description will be given of a calculation procedure when the advanced rate estimation value is lower than the allowable advanced rate lower limit value. According to the rolling theory, parameters controlling the advance ratio include (1) balance between the entrance tension and the exit tension, (2) the coefficient of friction, and (3) the rolling reduction.
Generally, there is a correlation between the rolling speed and the friction coefficient, and the friction coefficient can be increased by lowering the rolling speed. FIG. 10 shows this state. From this, it becomes possible to control the coefficient of friction by the rolling speed, and consequently to control the advanced ratio.

First, the balance between the entrance side tension and the exit side tension is changed within an allowable range, and the load estimated value, the torque estimated value, and the advanced rate estimation are again calculated by the equations (3), (4) and (5). Calculate the value. Here, when the advanced rate estimation value is equal to or larger than the allowable advanced rate lower limit value, it is further checked whether the load and torque estimated values satisfy the respective constraint conditions. Proceed to step. Otherwise, if the load constraint is not satisfied, the process returns to (Step 2), and if the torque constraint is not satisfied, the process returns to (Step 3).

If the rate is still lower than the lower limit of the allowable advanced rate, the following branch processing is executed in the calculation mode of the path schedule. In the case of the high-speed rolling mode, the exit side sheet thickness when the advanced ratio is set to the allowable lower limit of the advanced ratio is calculated by Newton's method using the equation (5). At this time, if the calculated outlet plate thickness is smaller than the finished plate thickness, the outlet plate thickness is set to the finished plate thickness. Further, the rolling load estimated value is calculated by the equation (3),
The estimated torque values are calculated by the equations (4), and the process proceeds to the next step. In the case of the minimum pass mode, the coefficient of friction is corrected upward by first correcting the rolling speed downward, and the advance rate is increased. Here, when the set rolling speed is lower than the base speed, or when the rolling speed is lower than the base speed by correcting the rolling speed, the rolling speed is set to the base speed, and the same calculation procedure as the high-speed rolling mode is performed. Take. In other cases, the load, torque, and estimated value of the advanced ratio are calculated by equations (3), (4), and (5), and the respective constraints are checked. If you are satisfied, proceed to the next step. Otherwise, if the load / torque does not satisfy the constraint,
Return to (Step 3). If the advance rate still does not satisfy the constraint conditions, the same calculation procedure as in the high-speed rolling mode is used to correct the reduction rate.

(Step 5) Select a gear of the tension device that satisfies both the tension determined in the process up to the above steps and the total tension set value calculated from the inlet / outlet plate thickness. At this time, if there are several gears that can be selected, and if there are several gears that can obtain the rolling speed set by the calculation procedure up to the above step, the gear having the widest tension setting range among them Set. In this case, when there are several gears that can be selected, and when there is no gear that can obtain the rolling speed set by the calculation procedure up to the above step, among them, the setting range of the rolling speed is the widest. Set the gear. At this time, if there is no gear that can be selected, the gear in the tension setting range closest to the tension value set by the calculation procedure up to the above step is set. Accordingly, the tension set value is changed. Further, when the rolling speed set by the above calculation procedure is out of the setting range of the gear rolling speed, the rolling speed is corrected to the maximum value within the setting range. Next, when the tension set value is changed within the allowable range, if it is possible to set a gear that enables higher-speed rolling, the tension, the rolling speed, and the selected gear are changed. If the rolling speed and tension change due to the above gear selection, the load, torque and advanced ratio estimated value are recalculated according to the equations (3), (4) and (5), respectively.
Check whether the load, torque and advance rate estimates satisfy the constraints. If you are satisfied,
Returning to (Step 1), the calculation of the next pass is executed. If any one of the constraint conditions is not satisfied, (Step 2), (Step 3), (Step 4)
Return to and execute recalculation. According to the above calculation procedure, the pass schedule at the highest rolling speed can be determined in the high-speed rolling mode, and the pass schedule at the maximum rolling reduction can be determined in the minimum-pass mode.

FIG. 4 is a flowchart showing a method for determining a path schedule according to the present invention. The outlet plate thickness and the finished plate thickness calculated in the above calculation procedure are compared, and if both are equal, the calculation is terminated. In other cases, the number of paths is incremented, and the process returns to (Step 1) of the calculation flow of FIG. 1 to continue the calculation. Hereinafter, the above calculation flow is referred to as a normal path / schedule determination flow.

Next, a path according to still another embodiment of the present invention will be described.
A method for determining a schedule will be described. Indices for evaluating the rolling efficiency include (1) rolling time, (2) energy required for rolling, (3) production cost, and the like. Here, the above-mentioned three indices have been cited, but if there are other indices for evaluating the rolling efficiency, it is also possible to consider them. Here, when the rolling time is used as the evaluation index, its definition is expressed by equation (7).

[0028]

(Equation 1)

In the above-described pass schedule determination method, it is also possible to arbitrarily set the rolling reduction distribution of each pass. The following are some examples. Set the rolling reduction of the first pass arbitrarily, and
The schedule determines the rolling reduction according to the calculation procedure of the flowchart of FIG. This is because the sheet thickness is distributed in the longitudinal direction of the original sheet manufactured in the hot rolling step, which is the preceding step of the cold rolling step, and a load change accompanying the sheet thickness is likely to occur, so that a shape defect is likely to occur. Therefore, set only the rolling reduction of the first pass low,
This is to avoid the occurrence of shape defects. This can be easily introduced in the path / schedule determination flow.

FIG. 5 is a flowchart showing a method of determining a pass schedule by allocating a rolling reduction so as to smooth a load. In this method, the rolling reduction distribution is set such that the rolling load has a constant value only in all passes or several passes before the final pass. Generally, optimal setting conditions such as a shape control device of a rolling mill, a roll bender, and the like change according to a load change. When the load variation between passes is large, a shape defect is likely to occur due to an error in the setting accuracy of the shape control device. Therefore, it is possible to reduce the shape defect due to the load variation by distributing the rolling reduction so that the load becomes constant. This is performed by performing the above-described path schedule calculation processing and performing convergence calculation using the allowable load upper limit value as a correction parameter. First, normal path schedule calculation is performed to determine the total number of paths N. Next, the number of passes M (1 ≦ M ≦ N−1) that makes the load equal to that of the final pass and the initial value of the smooth load are set. This smooth load is set to be equal to or less than the allowable load lower limit shown above. Next, from the (N−M) th pass to the Nth pass, (Step 1) to (Step 5)
The above calculation procedure up to is performed. At this time, the calculation is performed by setting a smooth load as the allowable load upper limit value. The smoothed load is corrected downward until the ratio between the load estimation value at the Nth pass and the allowable load upper limit falls within the allowable range (upper limit ratio: α _U , lower limit ratio: α _L ), and the convergence calculation is performed using this as a convergence parameter. continue.

FIG. 6 is a flowchart showing a method of determining a pass schedule when the rolling load of the final pass is designated. In this pass schedule determination method, a final pass load is specified, and a rolling reduction is distributed so that rolling loads in several passes before that are sequentially reduced. In general, when the rolling load exceeds a rolling load that causes a shape defect that exceeds the control capability of the shape control device, the shape defect increases. In operation, production efficiency is important together with the plate shape, so in the initial few passes, increase the production efficiency near the maximum load without considering the occurrence of shape defects, and consider the plate shape in the remaining passes in the second half The scheduled schedule will be useful. In order to improve the shape, set the rolling load in the final pass to a value at which the shape is good, and from the final pass to the previous several passes, the rolling reduction so that the load decreases linearly from the maximum load to the final pass load. Distribute. This is also processed by performing the above-described pass schedule calculation processing and performing convergence calculation using the allowable load upper limit as a correction parameter, similarly to the above-described example.

First, the number M of paths for linearly distributing the load before the final pass and the allowable load upper limit are set. Next, a normal path schedule calculation is executed, and the total number of paths N
To determine. Next, the load of the (N−M) pass from the last pass is set based on the equation (8). P _i = P _max − ((P _N ) set−P _max ) / M * (i−N + M) (8) where P _{i is} the set load of the _i- th pass, and (P _N ) set is N
The set load of the pass, _Pmax : the allowable load upper limit, M: the number of passes that distribute the load linearly, N: the total number of passes, and i: the i-th pass.

Next, the outgoing sheet thickness at the Nth pass is set to the finished sheet thickness, and the incoming sheet thickness when rolling at the previously set rolling load is calculated by the Newton method. (N-1) The entrance plate thickness of the Nth pass is set as the exit plate thickness of the pass, and the entrance plate thickness up to the (N-M) th pass is obtained in the same manner. If the entrance thickness calculated in the process exceeds the exit thickness of the (NM-1) pass before (NM), the allowable load upper limit value is updated from the beginning. Repeat the calculation procedure up to. In other cases, the load estimation value P _NM is calculated when the exit side plate thickness at the (N−M−1) pass is set to the entrance side plate thickness at the (N−M) pass. Calculated load estimated value P _NM
Until the ratio between the allowable load upper limit value _Pmax and the allowable load upper limit value _Pmax is within the allowable range (upper limit ratio: α _U , lower limit ratio: α _L ), the upper limit of the allowable load is set as the convergence parameter, and the process returns to the beginning of the calculation flow to execute the convergence calculation. . In the above, the convergence calculation was performed using the allowable load condition values. However, a linear form using the load, torque, and the influence coefficient of the advanced ratio for sheet thickness, tension, and rolling speed was constructed, and a matrix calculation method was used. Is also possible.
The calculation method is shown below. In this method, the above-described calculation procedures from (Step 1) to (Step 5) are executed, and the result is used as a reference schedule. Next, using a linear formula that uses the coefficient of influence for the load, torque, and advance rate of each pass on the in-thickness and the out-thickness, the reduction ratio of each pass is set so that the load distribution ratio of each pass is arbitrary. Is calculated.
FIG. 7 shows a specific calculation flow. By using this method, the operation time can be significantly reduced as compared with the repetition operation by the Newton method.

(Step 1) The reference schedule is determined according to the normal path schedule determination flow. (Step 2) Calculate the influence coefficient of the load, torque, and advance ratio on the entry side plate thickness and the exit side plate thickness based on the reference schedule. At this time, equations (3) to (5) are used. (Step 3) Arbitrarily give the load distribution ratio of each path.
At this time, the load of the i-pass is given by equation (9). _{P i = K i · P 0} ... (9) However, P _i: load i path K _i: i load distribution paths ratio P _0: reference load Next, from the reference schedule obtained in (Step 1) A simultaneous equation in which the amount of change in the thickness of the entrance and exit sides of each pass and the reference load are unknowns is constructed. This matrix expression is shown in Expression (10).

[0035]

(Equation 2)

(Step 4) The load P ₀ and the amount of change in the thickness of the entrance / exit side of each pass are calculated by the inverse matrix operation of the equation (10). (Step 5) Based on the results of (Step 4), the load and the inlet / outlet thickness of the reference schedule are changed. The following formula shows the situation.

[0037]

(Equation 3)

Here, N is the total number of paths in the reference schedule. Where (h ₀ ) _i ′: the thickness of the exit side of the i-pass in the reference schedule. (H ₁ ) _i ′: the thickness of the entrance side of the i-pass in the reference schedule. I do. Check that the change in the total tension satisfies the gear tension setting range, and if it is not correct, correct the unit tension. (Step 7) Load / torque / advance rate of each path (3)
The recalculation is performed according to the equations (5) to (5). The re-calculated load, torque, and advance ratio of the i-th pass are denoted by P _i , T _qi , and f _si , respectively. (Step 8) The reference schedule load P _i ′ calculated in step 5 is compared with the load P _i calculated in step 7, and if the load falls within a predetermined error range, the process proceeds to the next step. Otherwise, go back to (Step 2)
Recalculate the impact factor for the updated reference schedule. (Step 9) It is checked that the torque and the advance ratio calculated in Step 7 satisfy each constraint.
If satisfied, end the calculation. Otherwise,
If the torque of the i-th pass exceeds the torque upper limit, (1
The procedure returns to (step 4), replacing the equation (13) of the i-th pass in the equation (0). When the advanced rate of the i-th pass is less than the lower limit of the allowable advanced rate, the formula of the i-th pass of the equation (10) is changed to (1).
3) The expression is replaced with the expression (Step 4).

[0039]

(Equation 4)

FIG. 8 is a characteristic diagram showing a comparison between a path schedule determined based on the present invention and a path schedule determined based on the prior art. According to the characteristic diagram of FIG. 8, according to the pass schedule set by the conventional method, the allowable torque upper limit is exceeded in the first pass, and the rolling mill is overloaded. Is actually not possible. On the other hand, according to the path schedule determined according to the present invention, it is possible to determine a path schedule that satisfies the allowable torque upper limit over all paths.

[0041]

As described above, according to the present invention, the following effects can be obtained. (1) According to one aspect of the present invention, an allowable load upper limit value,
With the base torque of the drive system of the rolling mill body and the lower limit of the allowable advanced rate being the limiting conditions, the rolling reduction of each pass is determined to be the maximum, and the rolling speed is set to the maximum value that can be set at the determined rolling reduction. Then, the tension is set based on a preset tension reference value, and subsequently, the gear of the tension device is selected according to the thickness and tension of each pass, and the speed and the gear speed of the selected tension device are selected. Since the rolling speed and the tension were each finally determined based on the upper limit of the tension,
It is possible to avoid load overload on the rolling mill, power overload on the rolling mill, and abnormal rolling, minimize the number of passes, and realize high-speed rolling as much as possible. At the same time, by appropriately setting the gear of the tension device, it is possible to set an appropriate rolling speed. As a result, it is possible to set a pass schedule with high production efficiency.

(2) According to another aspect of the present invention, the rolling speed of each pass is controlled by using the upper limit of the allowable load, the base torque of the drive system of the rolling mill main body, and the lower limit of the allowable advanced rate as constraints. Set the maximum speed, determine the reduction rate accordingly,
The tension is set based on a preset tension reference value, and subsequently, the gear of the tension device is selected according to the thickness and tension of each pass, and the speed and the tension of the gear of the selected tension device are selected. Since the rolling speed and the tension were finally determined based on the upper limit of the constraint, the load overload on the rolling mill, the power overload on the rolling mill, and the abnormal rolling were avoided, and the gear of the tension device was used. High speed rolling at the maximum rolling speed of As a result, a pass schedule with high production efficiency can be set.

(3) According to still another aspect of the present invention, among the path schedules determined by the above method,
It is possible to determine the one with the highest rolling efficiency.
As a result, it is possible to set a pass schedule with the highest production efficiency.

[Brief description of the drawings]

FIG. 1 is a flowchart (part 1) illustrating a method of determining rolling conditions for each pass in the present invention.

FIG. 2 is a flowchart (part 2) illustrating a method of determining rolling conditions for each pass in the present invention.

FIG. 3 is a flowchart (part 3) illustrating a method of determining rolling conditions for each pass in the present invention.

FIG. 4 is a flowchart showing a method for determining a path schedule in the present invention 5.

FIG. 5 is a flowchart illustrating a method of determining a pass schedule by allocating a reduction ratio so as to smooth a load in the present invention.

FIG. 6 is a flowchart showing a method of determining a pass schedule when a rolling load of a final pass is designated in the present invention.

FIG. 7 is a flowchart for determining a reduction ratio distribution by the influence coefficient method.

FIG. 8 is a characteristic diagram comparing a path schedule determined based on the present invention with a path schedule determined based on the related art.

FIG. 9 is a characteristic diagram showing a result when an allowable advanced rate lower limit value is obtained by an experiment.

FIG. 10 is a characteristic diagram showing a correlation between a friction coefficient and a rolling speed.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomoyuki Hirakawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Seiichi Murata 1-1-2, Marunouchi, Chiyoda-ku, Tokyo Japan Inside Kokan Co., Ltd. (72) Inventor Noriyuki Suzuki 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Kokan Co., Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) B21B 37/16

Claims (3)

(57) [Claims] When determining a pass schedule for rolling a sheet using a reversible rolling mill, an upper limit of an allowable load, a base torque of a drive system of a rolling mill main body, and a lower limit of an allowable advance rate are set as constraints. Determine the rolling reduction of each pass to be the maximum, set the rolling speed to the maximum value that can be set in the rolling reduction, set the tension based on a preset tension reference value, and subsequently , The gear of the tension device,
A reversible rolling mill, wherein the rolling speed and the tension are each finally determined based on the selected upper limit of the gear speed and the tension of the gear of the selected tensioning device, selected according to the thickness and the tension of each pass. How to determine the path schedule. 2. A torque upper limit determined by an allowable load upper limit, a power upper limit of a drive system of a rolling mill main body, and a rolling speed in determining a pass schedule for rolling a sheet material using a reversible rolling mill. With the lower limit of the allowable advanced rate as a constraint, the rolling speed of each pass is set to the maximum speed of the rolling mill, the rolling reduction is determined accordingly, and the tension is set based on a preset tension reference value. Subsequently, the gear of the tension device is selected according to the thickness and tension of each pass, and the rolling speed and the tension are respectively finalized based on the upper limit of the speed and the tension of the selected gear of the tension device. A pass / schedule determination method for a reversible rolling mill, wherein the pass / schedule is determined. 3. The pass schedule is determined by the method of claim 1 and the pass method of claim 2, and both pass schedules are compared based on an index for evaluating the rolling efficiency. A pass / schedule determination method for a reversible rolling mill, characterized by employing: