JP6358222B2 - Pass schedule determination method when changing the thickness of the running plate in continuous cold rolling - Google Patents

Description

  The present invention relates to a method for determining a pass schedule when changing a running plate thickness when a cold rolled steel plate such as a tin plate or automobile steel plate is rolled by a continuous cold tandem rolling mill.

  Cold rolled steel sheets such as tin plate and automobile steel sheets are continuously cold tandem rolling mills (hereinafter simply referred to as “rolling mills”) composed of two or more continuous rolling stands (hereinafter also simply referred to as “stands”). In this case, the plate thickness is changed by changing the pass schedule while continuously rolling the material to be rolled.

  For this change in running plate thickness, the appropriate control is performed by the process computer and its subordinate PLC (Programmable Logic Controller) to suppress troubles such as plate breakage and to efficiently change the running plate thickness. Is disclosed.

  First, it is necessary to accurately predict the rolling load and advanced rate when changing the running plate thickness with a process computer. However, in Patent Document 1, the friction coefficient is learned using the actual data of the rolling mill, the rolling load, etc. This shows how to improve the prediction accuracy.

  Next, it is necessary to appropriately control the roll gap and the roll peripheral speed when changing the running plate thickness with PLC, but in Patent Document 2, the running plate thickness change point is tracked by the flow amount of the material to be rolled. This shows a method for controlling the reduction position and tension of each stand in a timely manner.

JP 2006-122980 A Japanese Patent Laid-Open No. 5-177223

  Conventionally, as a method for determining the pass schedule when changing the running plate thickness in continuous cold rolling, just before changing the running plate thickness, the rolling load of each stand is in the predetermined rolling load balance. However, this method cannot accurately consider the operating conditions such as roll wear at each stand, so select a pass schedule that is difficult to operate at high rolling speeds depending on the operating conditions. There was a case.

  Here, the rolling load balance is a ratio of the rolling load of each stand, for example, a value obtained by dividing the rolling load of each stand by the rolling load of the first stand.

  The present invention has been made in view of the circumstances as described above, and when determining the pass schedule at the time of changing the running plate thickness in continuous cold rolling, a highly efficient pass schedule that can always be stably rolled is calculated. It is an object of the present invention to provide a method for determining a pass schedule when changing a running plate thickness in continuous cold rolling.

  In order to solve the above problems, the present inventor has devised the following method as a result of intensive studies.

  That is, in continuous cold rolling, when determining the pass schedule at the time of changing the strip thickness of the material to be rolled, first, the process computer collects the strip of the material to be rolled from the past operation results collected. Rolls stably without seizing or slipping between the work roll and the material to be rolled under operating conditions close to the operating conditions when changing the thickness (work roll wear state depending on the rolling distance after the work roll is changed) Cases that were able to be operated efficiently were extracted. Next, the rolling load balance at the time of changing the running plate thickness in the case is calculated. And the pass schedule at the time of running plate thickness change which becomes the rolling load balance is calculated and determined.

  The present invention is based on the above idea and has the following characteristics.

  [1] In continuous cold rolling, when determining the pass schedule when changing the running plate thickness of the material to be rolled, the running time is changed under the operating conditions close to the operating conditions for changing the running plate thickness of the material to be rolled. Extracting high-efficiency cases that can be stably rolled from the past operation results of changing the thickness, calculating the rolling load balance in the extracted case, about the material to be rolled so that it becomes the rolling load balance A method for determining a pass schedule when changing a running plate thickness in continuous cold rolling, wherein a pass schedule when changing the running plate thickness is calculated and determined.

  [2] Rolling load balance in the conventional method for obtaining a pass schedule at the time of changing the running plate thickness by correcting the pass schedule immediately before changing the running plate thickness so as to be a predetermined rolling load balance, and the extracted stable rolling Comparing the rolling load balance in a high-efficiency case, and based on the comparison result, by correcting the pass schedule at the time of running plate thickness change by the conventional method, about the material to be rolled The method for determining a pass schedule when changing the thickness of a running plate in continuous cold rolling according to [1], wherein a pass schedule when changing the thickness of the running plate is calculated and determined.

  In the present invention, when determining the pass schedule at the time of changing the running plate thickness in continuous cold rolling, based on the past operation results of changing the running plate thickness under operating conditions close to the operating conditions of the material to be rolled. Since the rolling load balance is calculated, it is always more stable than when calculating the pass schedule when changing the plate thickness based on the default rolling load balance that does not take into account past operating conditions as in the conventional method. Rolling is possible and a highly efficient pass schedule can be calculated and determined.

It is a flowchart which shows the process sequence in one Embodiment of this invention.

  One embodiment of the present invention is described below.

  First, in a continuous cold rolling system according to an embodiment of the present invention, each stand of a continuous cold tandem rolling mill includes rolling load detection means (load cell, etc.), rolling position detection means, plate tension detection means, plate thickness detection means. Is equipped.

  Then, the process computer calculates the pass schedule, the predicted rolling load value of each stand, and the roll gap target value according to information such as the material slab dimensions and product target dimensions given from the host computer, and these values are transferred to the lower PLC. Set.

  The PLC continuously collects actual rolling data such as rolling load and tension and outputs it to a process computer.

  And in the continuous cold rolling system in this embodiment, as shown in FIG. 1, the pass schedule at the time of changing the strip thickness of the material to be rolled is determined by the following procedure.

(S1) Collection of Actual Rolling Data The PLC continuously collects actual rolling data such as rolling load and tension, and outputs it to the process computer.

(S2) Collection of actual data when changing the running plate thickness From the actual rolling data output by the PLC, the process computer changes the running plate thickness without causing seizure or slippage between the work roll and the material to be rolled. Collect time performance data. These data items to be collected are rolling data such as the rolling load of each stand and the tension between the stands.

(S3) Editing efficiency data Coil is cut with a coil shear on the continuous cold tandem rolling mill outlet, with data such as the maximum speed and target efficiency attainment required to calculate the efficiency of the material to be rolled (coil). Edit at the timing.

  The above (S1) to (S3) are repeated.

(S4) Extraction of high-efficiency operation data Operation that is close to the operation conditions (for example, the work roll wear state depending on the rolling distance after work roll replacement) of the material to be rolled (the material to be rolled) whose thickness is changed from now on A case of high-efficiency operation (for example, a case where the maximum rolling speed is high) is extracted from past operation results in which the sheet thickness change is performed under conditions. The extraction method is not specified in particular, but statistical methods are used to extract cases that fall within a predetermined percentage of the top and use the average value, or extract the operation results where specific data shows the maximum value. Good.

(S5) Calculation of rolling load balance From the case of the high-efficiency operation extracted in the above (S4), the rolling load balance at the time of changing the strip thickness is calculated.

(S6) Calculation of the pass schedule at the time of changing the running plate thickness The pass schedule at the time of changing the running plate thickness (tension between the stands, to be the rolling load balance at the time of changing the running plate thickness calculated in (S5) above. Calculate and determine the reduction rate of each stand, the roll speed of each stand, etc.

  As a method at that time, the rolling load balance in the pass schedule by the conventional method (a method of correcting the pass schedule immediately before the change of the running plate thickness so that the rolling load of each stand becomes a predetermined rolling load balance) The rolling load balance at the time of changing the running plate thickness calculated in the above (S5) may be compared, and based on the comparison result, the pass schedule according to the conventional method may be corrected.

  For example, the difference between the conventional method for each stand and the rolling load calculated in the above (S5) is obtained, and a predetermined ratio of the difference is added to or subtracted from the rolling load obtained by the conventional method to obtain a corrected rolling load. It is preferable to determine a pass schedule at the time of changing the running plate thickness so as to obtain a rolling load of.

  Thus, in this embodiment, when determining the pass schedule at the time of changing the running plate thickness in cold rolling, it is based on the past operating results of rolling under operating conditions close to the operating conditions of the material to be rolled. Since the rolling load balance is calculated, stable rolling is always performed as compared to the case where the pass schedule for changing the running plate thickness is calculated based on the default rolling load balance that does not take into consideration the operating conditions as in the conventional method. It is possible to calculate and determine a highly efficient pass schedule.

  As an example of the present invention, based on the above-described embodiment of the present invention, a pass schedule for changing the running plate thickness in cold rolling was determined.

  First, the cold rolling system targeted in this embodiment is as follows.

-Number of stands: 5 stands (1st to 5th stands)
・ Maximum line speed: 2000 mpm
-Work roll diameter: 500-600mmΦ
-Backup roll diameter: 1300-1400mmΦ
・ Rolling load detection: Measured at each stand ・ Draft position detection: Measured at each stand ・ Plate tension detection: Measured between continuous cold tandem rolling mill entry and exit sides, each stand ・ Plate thickness detection: First stand exit side, fifth Measured on the stand exit side

  And the pass schedule at the time of running thickness change was determined as follows.

(S1) Collection of actual rolling data The PLC continuously collected actual rolling data such as rolling load and tension, and output it to the process computer.

(S2) Collection of actual data when changing the running plate thickness From the actual rolling data output by the PLC, the process computer changes the running plate thickness without causing seizure or slippage between the work roll and the material to be rolled. The performance data of time was also collected. These data items to be collected are rolling data such as the rolling load of each stand and the tension between the stands.

(S3) Editing efficiency data Coil is cut with a coil shear on the continuous cold tandem rolling mill outlet, with data such as the maximum speed and target efficiency attainment required to calculate the efficiency of the material to be rolled (coil). I edited it at the timing.

  The above (S1) to (S3) were repeated.

(S4) Extraction of high-efficiency operation data High-efficiency operation based on past operation results of changing the plate thickness under the operating conditions close to the operating conditions of the material to be rolled (the material to be rolled) from which the plate thickness is changed Cases were extracted.

  Specifically, the upper 20% cases of the maximum speed falling within the range of ± 10% of the work roll rolling distance of the stand were extracted for each stand.

(S5) Calculation of rolling load balance From the case of the high efficiency operation extracted in the above (S4), the rolling load balance at the time of changing the strip thickness was calculated.

  Specifically, in the extracted top 20% cases, the rolling load ratio is calculated by dividing the rolling load of the second stand to the fifth stand by the rolling load of the first stand for each case, and then for each stand. The average value of the rolling load ratio was calculated, and the average value of the rolling load ratio for each stand was defined as the rolling load balance. At that time, the dispersion value V of the rolling load ratio was also calculated for each stand.

(S6) Calculation of pass schedule at the time of changing the plate thickness The pass schedule at the time of changing the plate thickness was calculated and determined so that the rolling load balance at the time of changing the plate thickness calculated in (S5) was obtained. .

  Specifically, first, the rolling load for each stand is calculated by a conventional method (a method of correcting the pass schedule immediately before the change of the running plate thickness so that the rolling load of each stand becomes a predetermined rolling load balance). From there, the rolling load of the second stand to the fifth stand was divided by the rolling load of the first stand, and the rolling load balance according to the conventional method was calculated.

  Next, for each stand, the rolling load balance calculated by the conventional method is compared with the rolling load balance calculated in the above (S5), and within the range of the dispersion value (± V) calculated in the above (S5). If the rolling load balance calculated by the conventional method is out of the range, the rolling condition of the stand in the conventional method (NG stand) is changed so that it is within the range. did.

  For example, except for the final stand, when the Qth to Q + N stands are NG stands, the contents described below were implemented.

-The downstream stand in the NG stand does not change the entry side plate thickness (that is, the rolling load is increased or decreased by changing the rolling reduction (outside plate thickness)).
The upstream stand in the NG stand does not change the rolling reduction (that is, the rolling load is increased or decreased by changing the plate thickness).
-The plate thickness change in the NG stand is adjusted by changing the rolling reduction (outside plate thickness) of the Q-1 stand.

  Alternatively, when the P-th stand is an NG stand, the reduction rate of the P-th stand is decreased (increased), the P-th stand outlet side plate thickness is increased (decreased), and the P + 1th stand is adjusted. Others did not change.

  In addition, when changing the reduction rate (exit side plate thickness) of the stand immediately before the final stand, the reduction rate of the final stand was changed and adjusted to the target plate thickness after continuous cold tandem rolling.

  For example, the following formulas (1) to (4) are used for the amount of change in the rolling reduction of the NG stand.

  More specifically, in the 5-stand continuous cold tandem rolling mill, when the third to fourth stands were NG stands, the following contents were implemented.

-The 4th stand which is a downstream stand in the NG stand did not change the entry side plate thickness, but changed the rolling reduction and increased or decreased the rolling load.
-The 3rd stand which is an upstream side stand in a NG stand did not change the rolling reduction, but changed the plate thickness, and increased / decreased rolling load.
-The plate thickness change in the NG stand was adjusted by changing the rolling reduction (outside plate thickness) of the second stand.
-The fifth stand as the final stand was adjusted to the target thickness after continuous cold tandem rolling by changing the rolling reduction.

  As another example, when the second stand is an NG stand, the reduction rate of the second stand is decreased (increased), the thickness of the second stand exit side plate is increased (decreased), and the third stand is adjusted. . Others did not change.

  As a result, high-efficiency rolling that does not always cause seizure or slip between the work roll and the material to be rolled is possible, and the rolling efficiency of the present invention is increased by 2.5% compared to the conventional one.

Claims (2)

In continuous cold rolling, when determining the pass schedule when changing the sheet thickness of the material to be rolled,
Process computer
With respect to the rolling distance after the work roll change in the work roll when changing the running plate thickness of the material to be rolled, the running thickness change with the work roll in which the rolling distance after the work roll change falls within a predetermined ratio From the past operational results , the seizure and slip between the work roll and the material to be rolled did not occur, and the cases where the maximum rolling speed was high and entered the upper predetermined ratio were extracted, and the rolling load balance in the extracted cases Calculating and determining the pass schedule when changing the strip thickness for the material to be rolled so that the rolling load balance is calculated, and changing the strip thickness in continuous cold rolling How to determine the time pass schedule. The rolling load balance in the conventional method for obtaining the pass schedule at the time of changing the thickness of the running plate by correcting the pass schedule immediately before the change of the running plate thickness so as to be a predetermined rolling load balance, the extracted work roll and the material to be rolled. Compared with the rolling load balance in the case where the highest rate of rolling does not cause seizure and slip, and the maximum rolling speed is high, the rolling load according to the conventional method for each stand and the extracted case Determine the difference in rolling load, and add or subtract the predetermined percentage of the difference to the rolling load obtained by the conventional method to obtain the corrected rolling load. The pass schedule determination method at the time of running plate thickness change in continuous cold rolling according to claim 1, wherein a pass schedule at the time of plate thickness change is calculated and determined.

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