JP2001198611A - Rough rolling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the on-line variable control of a reduction schedule for a roughing mill, to control a temperature drop between the roughing mill and the inlet side of finishing and to reduce stand-by time on the inlet side of a finishing mill. SOLUTION: The stand-by time before finish rolling of a next rolled stock is estimated from the information of the rolled stock on a line and information of the next rolled stock, the reduction schedule of rough rolling of the next rolled stock is calculated so as to minimize this stand-by time and, after determining the reduction schedule so as to be within the restriction of rolling, rough rolling is performed by this reduction schedule.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a rough rolling method. More specifically, the present invention relates to a technique for minimizing a standby time before finish rolling at an outlet of a rough rolling mill in hot rolling to achieve high productivity.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 6-7823 discloses a technique for improving the efficiency of a rough rolling process in a hot rolling factory.
A technique is disclosed in which the time at which a rolled material is extracted from a heating furnace is adjusted to minimize the pitch at which the material enters a finishing mill in consideration of the extraction temperature condition of the rolled material. That is, in the rolling line having a heating furnace, by controlling the extraction pitch after determining the standby time in the rough rolling mill region from the extraction temperature,
The purpose of the present invention is to realize rolling at a minimum rolling pitch while satisfying the temperature restriction on the side of the finish rolling mill. This technology calculates the rolling schedule of the rolled material in the heating furnace furnace of the rolled material, obtains the estimated time of transportation through each equipment and each path from the time of extracting the heating furnace, and also calculates the estimated time of transportation. And in the method of determining the extraction time from the heating furnace for each rolled material, if the temperature of the rolled material to be extracted is overheated by a predetermined amount or more than the target temperature on the exit side of the heating furnace, the extraction time is advanced. This is a technique in which the extracted rolled material is made to stand by for a predetermined time in a rough rolling pass or the like, and is cooled to a predetermined temperature before it reaches the finishing mill input side.

[0003] This technique predicts the occurrence of standby on the finishing side in advance to advance the timing of heating and extraction, and has an object to obtain a necessary temperature drop during standby in a rough rolling mill area. However, waiting in the rough rolling mill area causes a local temperature drop due to heat removal to the transport rollers,
Thereafter, it has been found that it becomes a factor of defective temperature and poor thickness and width in finish rolling. Further, in this technique, the control of the waiting time for the temperature drop of the rolled material before entering the finishing mill is not performed, so there is room for improvement in this respect.

[0004] In addition, the problem of furnace loss (fuel loss) due to irregularities in the extraction pitch of the heating furnace, or the return of trouble occurrence after finishing due to the increase in the number of slabs on the line due to the advance of slabs There is also a disadvantage that the number of materials increases.

[0005]

Therefore, there is a need for a method which solves these problems and ensures high productivity.
In this case, it is a condition that the material extracted from the heating furnace is always progressing toward the finishing mill, or that a rough rolling mill operation that does not adversely affect the furnace can be performed with a relatively constant extraction pitch. .

[0006] The present invention controls the temperature drop from the rough rolling mill to the entrance of the finishing rolling mill by online variable control of the rolling schedule in the rough rolling mill, thereby reducing the standby time on the entrance side of the finishing rolling mill. And to conduct highly efficient operations.

[0007]

SUMMARY OF THE INVENTION The present invention has been developed based on the above-mentioned circumstances to achieve higher-efficiency production.
The technical means predicts a standby time before finish rolling of the next rolled material from the information of the rolled material on the line and the information of the next rolled material, and a rough rolling reduction schedule of the next rolled material so as to minimize the standby time. Is calculated so that the rolling schedule is within the rolling constraints of the rough rolling mill, and then rough rolling is performed in the rolling schedule.

[0008] In this case, it is preferable that the rolling schedule mainly adjusts a rolling reduction in a former stage or a latter stage of the rough rolling mill according to the predicted standby time. Further, by performing learning control on the prediction of the standby time,
Prediction calculation taking into account the inherent characteristics of the equipment becomes possible, and the accuracy in that line can be improved.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to expand direct hot-charge rolling for realizing low-cost and high-productivity operation, expansion of so-called roll chance-free technology that eliminates rolling regulations has become an essential issue. . As one of the problems, when materials having different extraction temperatures are heated adjacently in the heating furnace, there is a problem that productivity is reduced. Rolled material with different heating temperature, for example, high temperature material A
When the low-temperature material B and the low-temperature material B are adjacent to each other in the heating furnace, the operation of the heating furnace increases in accordance with the extraction temperature of the high-temperature material A,
The low temperature material B is also extracted at a high temperature. The low-temperature material B extracted by overheating performs a standby for a temperature drop in a rough rolling region before the finishing side in order to secure a finish rolling temperature, which causes a reduction in rolling efficiency.

Therefore, the amount of temperature drop from the rough rolling mill to the entrance of the finishing rolling mill is controlled by making the rolling schedule in the rough rolling mill variable. That is, it is possible to increase the temperature drop amount from the rough rolling mill to the entrance of the finishing rolling mill by setting the first stage of the rough rolling machine to a high pressure reduction, and it is also possible to set the rough reduction by setting the subsequent stage of the rough rolling mill to a high pressure reduction. The amount of temperature drop between the rolling mill and the entrance to the finishing mill can be kept small.

According to the present invention, the control predicts a standby time for a temperature drop in accordance with the order of extracting the rolled material in the heating furnace, and sets a rolling reduction and a sheet thickness at each stand of the rough rolling mill according to the standby time.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart showing an example of the method of the present invention. First, the next rolled material information 1 is input. This information includes the slab extraction temperature, the finishing side temperature, the order of extraction of the rolled material in the furnace, and the like. Next, rolled material information 2 on the line is input. This information includes the extraction temperature, the finishing temperature, the standby time, and the like. Based on these information, the predicted value calculation 3 of the standby time before entering the finishing mill in the standard rolling mill rolling schedule of the next rolled material is performed. In the calculation of the predicted value, it is preferable to perform learning control by feedback of the actual value so as to obtain a value in consideration of the circumstances specific to the line. The predicted calculation value is checked 4 to determine whether or not it is necessary to make correction by further referring to the information of the next rolled material and the information and results of the rolled material on the line. If correction is necessary, the prediction value is recalculated. If there is no need for correction, the rolling schedule calculation 5 of the rough rolling mill is performed so that this waiting time is minimized. The rolling schedule appropriately determines the value of the rolling reduction in each stage of the rough rolling mill. In this case, if the predicted standby time is large, the draft reduction adjustment at the front side of the rough rolling mill is made larger than usual, and if the predicted standby time is small, the draft reduction adjustment at the latter stage of the rough rolling mill is made larger than usual. It is easy to determine if the rolling schedule is determined. Next, a check 6 is performed to determine whether or not the predicted standby time becomes minimum when rough rolling is performed by the schedule calculation, that is, whether the predicted standby time matches the predicted value. If it is not appropriate, the third and subsequent predicted value calculations are repeated.

The re-checked and passed values are subjected to rolling constraint addition 7 of the rough rolling mill. For example, a check 8 is performed to determine whether the upper and lower limits of the coarse bar thickness, the upper and lower limits of the amount of reduction of each stand, and the upper and lower limits of the allowable load are within the constraints. For example, if the amount of reduction is excessive, there is a problem that an edge seam is generated. Therefore, this restriction is important. If it is appropriate, the rough rolling is performed 9 in this rolling schedule. If it is not within the constraints, the rough rolling is performed with corrections made to match the constraints.

FIG. 2 is a chart illustrating a rolling schedule for minimizing the waiting time according to the present invention. The horizontal axis indicates the time at each step-out side position of the rough rolling mill (for example, coarse 1 indicates the exit side position of the first step rough rolling mill), and the vertical axis indicates the average temperature of the rolled material. For example, the present invention is applied to a material that progresses as shown by a curve 11. In the material reduction schedule 2 shown by the curve 11, the finishing inlet temperature 13 after leaving the rough rolling mill 5 stages is higher than the appropriate temperature for the finish rolling.
In order to cool down to 4, a waiting time 15 occurs. In this rolling schedule, curve 1 is set so that the waiting time 15 becomes zero.
Change the rolling schedule, as shown at 2. Curve 1
In step 2, the rolling reduction of the first and second stages of the rough rolling mill is increased, the thickness of the rolled material is reduced to promote cooling, and the entrance temperature of the finishing mill is increased to 14
Can be made appropriate.

[0015]

According to the present invention, the standby time of the rolled material before the finish rolling mill can be minimized, so that the optimum high productivity rough rolling can be achieved. In addition, the present invention has excellent effects such as contributing to the optimization of the rough rolling process from a thermoeconomic point of view by combining the control of extracting the rolled material from the heating furnace.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an example of the present invention.

FIG. 2 is a diagram illustrating the operation of the present invention.

[Explanation of symbols]

 1 Next rolled material information 2 Rolled material information on line 3 Prediction value calculation 4 Check 5 Schedule calculation 6 Check 7 Rolling constraint addition 8 Check 9 Execution 11,12 Curve 13,14 Temperature 15 Standby time

Claims (3)

[Claims] 1. A waiting time before finish rolling of a next rolled material is predicted from information of a rolled material on a line and information of a next rolled material, and a rough rolling reduction of the next rolled material is performed so as to minimize the waiting time. A rough rolling method comprising calculating a schedule, setting the rolling schedule to be within the rolling constraints of the rough rolling mill, and then performing rough rolling with the rolling schedule. 2. The method according to claim 1, wherein the rolling schedule mainly adjusts a rolling reduction in a preceding stage or a subsequent stage of the rough rolling mill according to the magnitude of the predicted standby time. 3. The rough rolling method according to claim 1, wherein the prediction of the standby time is controlled by learning.