JP2528048B2 - Temperature control method in plate rolling - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention automatically realizes a target planned rolling temperature in advance when it is necessary to carry out rolling while adjusting the temperature of the material in the rolling process for the purpose of controlling the material quality. The present invention relates to a plate rolling method.

[0002]

2. Description of the Related Art In conventional plate rolling, a method for achieving a planned rolling temperature is to simply measure the material temperature during rolling and the operator of the rolling mill depending on the measured temperature. Adjustment was performed by arbitrarily adjusting the waiting time between passes or changing the rolling speed for each pass.

Further, as means for predicting the rolling temperature of several passes after the next pass, the estimated temperature of the pass schedule calculation result determined before rolling and the measured temperature of the current pass are compared and estimated from the difference. However, the rolling method that positively adjusts the time after the next pass has not been realized.

[0004]

In the conventional plate rolling, there is no method for accurately recognizing how the rolling temperature after a few passes actually changes, and even if it can be predicted, It is difficult to properly determine the adjustment method after this pass, and as a result, there is a problem in that the scheduled temperature cannot be secured during the scheduled pass.

Further, the temperature to be ensured during rolling is not limited to the final finishing temperature, but the rolling start temperature and the temperature in the middle pass may be regulated to control the material quality.
At this time, there is a problem that it is not enough to adjust the temperature after measuring the material temperature during rolling.

Further, as a means for adjusting the temperature, the driver arbitrarily determines and controls the temperature from the actually measured temperature during the rolling pass. Therefore, waiting time with a large variation may occur during the rolling, and during the rolling. However, there is a problem in that the temperature does not drop smoothly and uniformly, and the material varies.

The object of the present invention has been made in view of the above-mentioned circumstances of the prior art. When rolling a plate material while adjusting the temperature in a reversible plate rolling machine, the target regulation temperature is automatically and accurately determined. It is to provide a rolling method that can be ensured.

[0008]

In order to achieve the above object, the present invention comprises one or two reversible plate rolling mills,
By automatically controlling the rolling speed and the time between passes using a sequencer (DDC) and process computer that can automatically control the plate material transport table around the rolling mill, and a sensor group that can collect actual information on the plate material The method for achieving the regulated temperature during rolling is realized.

That is, before the actual rolling, at the stage of the pass schedule calculation, the temperature drop amount of the sheet material during rolling is strictly predicted and calculated, and rolling is performed under the assumption of standard rolling speed and time between passes. It is determined whether the regulated temperature can be secured on the way. When it is predicted that the regulated temperature cannot be ensured, the standard rolling speed and the time between each pass are corrected within the range of the equipment process capacity according to the predicted temperature and the level of the regulated temperature. Try to recreate the optimal path schedule that can be achieved. The target temperature at the start of rolling and the target temperatures for all passes are determined by the above-described preliminary pass schedule calculation.

Then, during the actual rolling of the plate material, the process computer recognizes the difference from the target temperature while measuring the actual plate material temperature in real time for each pass from the start of rolling, and the initial stage After instructing the operator the rolling start timing, the rolling speed of each pass and the temperature waiting delay time between passes were corrected,
Causes the DDC to transmit rolling mill control information. The DDC receives the speed information and the time information from the process controller, controls the mill motor speed of the rolling mill, and the normal / reverse rotation start / stop timing of the table to realize the rolling to secure the target rolling temperature.

[00011]

According to the above-mentioned means, the rolling temperature schedules for all the passes are determined in advance according to the regulated temperature. Therefore, first, the optimum timing for starting the rolling is accurately operated from the preliminary stage of the rolling start. It becomes possible for the person to recognize. In addition, the target value of the rolling temperature schedule for all passes is clear, and the speed and waiting time are automatically adjusted based on the difference between the scheduled temperature and the actual temperature. Thus, smooth rolling can be realized from the start to the end of rolling. As a result, not only can the regulated temperature be accurately ensured, but unpredictable time waiting between rolling passes can be eliminated, so it is possible to understand the proper timing for extracting the rolled material from the heating furnace. It is also possible to reduce unnecessary rolling waiting time.

[00012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a control system that realizes the plate rolling method according to the present invention. First,
The configuration of FIG. 1 will be described. Process computer 1
Is a finish pass schedule calculation unit that receives the steel plate information from the business computer 2 and calculates a schedule such as the plate thickness and temperature for each pass in advance before starting the rolling to determine the process processing contents of the entire finish rolling pass. 1A, the schedule obtained by this pass schedule calculation unit 1A is transmitted to the finishing plant controller 3 described later while actually rolling the plate for each pass, and the actual performance information is passed to the next pass between the passes. The learning adaptive control calculation unit 1B is configured to perform a feedforward learning calculation in real time and execute a more accurate next path setting calculation. Further, a radiation thermometer 5 for detecting the surface temperature of the material to be rolled 4 during rolling, a table roll 6 positioned on the front and rear surfaces of the mill to convey the material to be rolled in synchronization with the mill speed, and a work of a rolling mill. Roll 7, mill motor 8A for driving work rolls at a set speed from DDC, motor current control unit 8B, table motor 9 for driving table rolls at a set speed from DDC, like the mill motor, material to be rolled is rolled into a rolling mill. It is composed of a load cell 10 for detecting whether it is in a bite and a backup roll 11 of a rolling mill.

FIG. 2 is a flow chart showing an outline of the processing for realizing the pass schedule calculation on the premise of the temperature controlled rolling in the thick plate rolling according to the present invention. Hereinafter, the processing contents of the pass schedule calculation will be described according to this flowchart. Before entering this processing calculation, the plate thickness schedules for all the passes have already been determined, and the data is set as an initial value (step 1: hereinafter abbreviated as S1). The draft (sheet thickness) schedule set here is generally determined so as to satisfy the rolling load and the sheet shape, and is determined after appropriate load distribution. In this embodiment, the draft schedule is as follows. Rolling start 1 2 3 4 5 6 7 8 9 Outlet plate thickness 80 70 60 60 50 40 30 20 18 15 12 Then, as a premise to predict the accurate temperature of the rolled material,
The biting temperature at the start of rolling is set (S2). The method of determining the bite temperature set at this time differs depending on the following conditions. A flow chart of this determination method is shown in FIG.

FIG. 3 is a flowchart showing a process for setting the initial bite temperature. In FIG. 3, first, it is determined whether or not a temperature determination flag, which will be described later, has already been set (S31), and if the bite temperature has already been determined from some temperature constraint condition, the process proceeds to S40 and is determined. Adopted temperature. Next, if the biting temperature is not determined, rough rolling, which is the pre-stage of finish rolling, has already been completed at the time when the pass schedule of finish rolling is to be calculated, and the end actual temperature is captured. It is determined whether or not (S32). If it is taken in, the process proceeds to S36, and if there is no actual temperature or the rough rolling is not yet finished, the process proceeds to S33. In S33, it is determined whether or not the biting temperature is specified for the material to be rolled due to material restrictions. If it is not a temperature designating material, the initial start temperature may be arbitrarily predicted and determined from the outside (S34), and if it is a temperature designating material, the designated temperature is set as the finish trapping temperature (S35). On the other hand, when the rough rolling is finished and there is the actual temperature, the predicted finish biting temperature is calculated under the condition that there is no waiting time in the normal transportation time from the actual temperature of the rough rolling to the finish rolling (S36). Then, if it is a bite temperature designating material (S37), the designated temperature is set regardless of the presence or absence of a temperature margin (S39), otherwise, the predicted temperature is set as it is as a bite temperature (S38). In this embodiment, 850 ° C. biting is designated by the biting temperature designating material,
If rough rolling has not been completed yet, S31 → S3
The biting temperature surface was set to 850 ° C. by the processing flow of 2 → S33 → S35.

Then, in S3 of FIG. 2, the internal temperature distribution in the plate thickness direction is predicted in order to accurately predict the initial temperature. As a method of predicting, (1) Predicting by heat transfer difference calculation in the plate thickness direction from the heating history process stage in the heating furnace, and adding the conditions of air cooling, roll bite and water cooling (descaling water) in the subsequent rough rolling, There is a method of predicting the temperature drop in each process and (2) a method of estimating the internal temperature distribution shape from the measured surface temperature and plate thickness at the end of rough rolling and simply predicting. In this example, the temperature at the start was calculated to be as follows using the method described below.

[Table 1] In addition, this prediction method is described in “Heat Transfer Engineering (above)” J. P. Hoffman, P29-31, 1982.

With the above calculations, the initial temperature calculation, which is a prerequisite for starting the calculation for each path, is completed, and the iterative calculation flow for performing the temperature determination for each path will be described below. The blocks shown in S4 to S15 in FIG.
This is a flow showing the calculation process in the path, and here is the main calculation unit that determines the basic temperature and load schedule for each path, and the same block calculation is performed regardless of the temperature judgment conditions. Become.

The operation of FIG. 2 will be described. A sheet thickness schedule is set from the outside in advance (S1), and a transfer temperature is initially set according to a temperature constraint condition and a rough rolling end result (bite temperature setting (S2)). To do. After that, the internal temperature of the plate thickness during transfer is calculated (S3). Next, the rolling speed of each pass is set (S4), the descaling execution presence or absence of each pass is set (S5), and each pass 1 cycle is (a) inlet side air cooling, (b).
Inlet water cooling, (c) Roll bite, (d) Outlet water cooling,
(E) Divide into the air-cooling on the outlet side and predict each time (S
6). Then, the temperature difference between the temperature at the outlet side of the previous pass and the temperature at the inlet side of this pass is calculated as a time difference (S7), the temperature at the designated pass is determined (S8), and the temperature at the inlet side of this pass needs to be corrected. Only in that case, the correction calculation is performed (S16). If the correction calculation is not necessary in S8, the rolling load calculation is performed (S
9), the rolling torque is calculated (S10). Then, the load is checked (S11), and if the load is not normal at that time, the number of passes is corrected and the corrected thickness schedule is created (S17), and the process returns to S2. Also, when the load is normal,
Calculate the temperature change in the roll bite (S1
2) A time difference calculation is performed on the temperature drop amount between the temperature on the inlet side of the pass and the temperature on the outlet side of the pass (S13). Next, it is judged whether or not it is the finishing exit (S14), and if it is not the finishing exit, it goes from this pass exit side to the next pass entrance side (S18) and returns to S4. ), The temperature delay time is calculated (S15). For a detailed explanation of each of these calculations, refer to "3rd Edition Iron and Steel Handbook III".
(1) Rolling foundation / steel sheet "(edited by Japan Iron and Steel Institute, P259,
The path schedule calculation flowchart of FIG. 6.60 described in 1980) is adopted. The temperature regulation check of the content of this application is added to this. S9: Rolling load calculation is "plate rolling theory and practice"
(The Iron and Steel Institute of Japan, 1984) The Sims formula of P287 is adopted. S10: The rolling torque calculation is “Theory and practice of sheet rolling” (edited by Japan Iron and Steel Institute, 1984), P21, Brand.
Adopted & Ford formula. S7, S13: The one-dimensional backward difference method is used for the difference calculation of the temperature drop amount on the path inlet and outlet sides. S12: The temperature change calculation in the roll bite is “theory and practice of sheet rolling” (edited by Japan Iron and Steel Institute, P148-P14).
9, 1984).

FIG. 4 is a flow chart showing in more detail how S4 to S14 of FIG. 2 are repeatedly calculated according to each temperature constraint condition. In the following, the elastic calculation flow in the overall process branch flow will be described simultaneously with reference to FIG. First, in FIG.
It is determined whether or not the material to be rolled is a temperature regulated material (S4-
1). At this time, when there is no temperature regulation, the processing of S4-2 is divided into the block calculation of S4 to S14 in FIG.
That is, the rolling speed of this pass is set. In setting the rolling speed, a standard roll speed is usually provided depending on the plate size, and the rolling speed pattern of the plate material is determined by, for example, a table value for each thickness / length.
Next, after determining whether or not descaling injection is required to remove the scale (iron oxide film) generated on the surface of the material to be rolled by this pass (S5 in FIG. 2), the pass time in this pass is divided into elements. And calculate the prediction.

FIG. 5 is a schematic diagram showing time element division for each path. In FIG. 5, (A) from the timing when the plate tail portion of the previous pass (i-1) is metal-off (when the plate tail part comes out of the state of being caught in the roll) (A ′) to the same time point in this pass (i pass) is 1 As a cycle, between (A) and (B): (i-1) Timing when the plate tail part of the path is metal-off ↓ The timing when the plate middle of the i-path enters the death spray zone is the entry side of the i-path. This is referred to as the air cooling time and is described as Δt _AB . Between (B) and (C): The timing at which the plate middle enters the Desk spray zone and the plate middle is metal-in is referred to as the i-pass inlet side water cooling time, and is described as Δt _BC . Between (C) and (E): The timing at which the plate middle is metal-in and the plate middle is metal-off is called the roll pass time of the i-pass, and is described as Δt _CE . Between (E) and (F): The metal of the plate middle is turned off. ↓ The timing when the plate middle exits the deskespray zone is called the exit side water cooling time of the i-pass and is described as Δt _EF . Between (F)-(A) ': The timing when the plate middle passes through the Desk Spray Zone and the metal part of the plate tail of the i-pass is turned off is called the e-pass air-cooling time on the i-pass, and is denoted as Δt _FA . Each time is predicted and set as 5 divisions.

This time element setting includes (i-) in addition to the estimation calculation from the rolling speed set in S4 of FIG. 2, the Desplay spray zone distance, and the contact arc length in the roll bite.
This can be easily calculated by setting 1) the time between passes and i-path, that is, the time between (i-1) path tail metal off to (i-1) path front metal in timing. The time between passes and the rolling speed are control factors in the temperature control material described later. The initial standard time between passes may be simply set as the average time in the actual operation system from the slab size and weight.

Next, in FIG. 2S7, the temperature drop amount at the timing to the roll entrance side is predicted among the element times divided. That is, in the temperature drop calculation, in this embodiment, the method of differentially expanding the heat transfer calculation is used. That is, the element time is further divided into minute time intervals, and the heat conduction from the surface and the amount of heat transfer to the inside are calculated by dividing the element time into 4 to 10 in the plate thickness direction of the rolled material,
Calculate the temperature drop during air or water cooling. This calculation is described in "Heat transfer engineering (above) P119". Since the actual temperature at the roll entrance side of this pass has been clarified up to this point, the rolling load prediction of the material to be rolled is predicted. 2S9 and S10, the rolling load / torque estimation calculation is performed, and in S11, it is checked whether the rolling load is within the equipment constraint condition.
If the load is over, the process returns to S1 of FIG. 2 to re-correct the draft schedule calculation. In the calculation of the temperature change of the roll bite in FIG. 2S12, the amount of temperature change is estimated and calculated in consideration of the heat generated by processing, the heat generated by friction, and the heat removed by the contact with the roll. Further, the temperature drop on the output side of the pass is calculated in the same manner as on the input side, and the temperature calculation for one pass is completed. This calculation adopts the contents described in "Theory and practice of sheet rolling" edited by the Iron and Steel Institute of Japan, P148-P149, 1984.

FIG. 6 shows the calculation result in the second pass from the initial stage in the embodiment. Roll entrance side plate thickness 80 mm Exit side plate thickness 70 mm 1st pass TIM (1) 2.30 seconds 2nd pass TIM (2) 2.40 seconds TOM (2)
4.80 seconds Δt _AB ≈TOM (2) + (TIM (2) / 2) −Δt _BC
≒ 6.0 seconds _{△ t BC ≒ Z / V R} = 0.0124S △ t CE ≒ Ld / V R = 0.0456S △ t EF ≒ 0 △ t FA ≒ TIM (2) /2≒1.20S

The above is the general processing flow for one pass, but when this is a temperature regulating material, S4 in FIG.
-3 processing. Here, as the temperature regulating material,
There are the following four patterns. Engagement Intermediate pass Before finishing 1 reduction I × × ○ ○ With regulation II ○ × ○ × Without regulation III × ○ ○ IV ○ ○ ○

If there is no regulation of the intermediate temperature in S4-3 of FIG. 4, the pattern is I or II, and the process branches to S4-4. In S4-4, the pass schedule is calculated from the initial bite pass to the last pass. At this time, in the first calculation, the standard time between passes and the rolling speed are sequentially calculated. And
In S4-5, the inlet temperature before the last pass is calculated, it is determined in S4-6 whether the temperature is within the regulation temperature, and if OK, the load of the last pass is calculated in S4-7 and the process ends. To do. In S4-6, the temperature of the last path is N
In the case of G, the time between each pass and the correction amount of the rolling speed of each pass are determined in S4-8, and the temperature is calculated again after returning to the process of S4-4. On the other hand, when the intermediate temperature is regulated, the pattern is the pattern III or the pattern IV, and the process branches to S4-9. In the flow from S4-9 and below,
First, the schedule determination part S4-from the initial stage to the intermediate pass
9 to S4-12 and S4 from the intermediate pass to the last pass
It is determined separately for the part of -13 and below. First, S4-
In 9, the completely same processing as the processing of S4-4A to S4-7 shown above is calculated for intermediate paths. Then, in S4-13 and thereafter, the path schedule calculation from the intermediate path to the last path before is similarly performed.

A method for checking and correcting the regulated temperature will be described below in sequence. This shows the logic contents to judge whether to perform the temperature judgment at the time of calculating the pass schedule and recalculate to the correction of the bite temperature or the time between passes (TOM), and the output items are those after the correction. Transfer temperature, temperature correction flag THFLAG, air-cooling time correction amount between passes: Δtt. On the other hand, the items that should be known are T1SO (specified transfer temperature) upper limit value, target value, lower limit value, TCHU (specified intermediate temperature) upper limit value, target value, lower limit value, TIAS (specified temperature before 1 pressure reduction) upper limit value, The target value, lower limit value, and NC (number of designated intermediate temperature paths) are given by information from the business computer. Further, NT (total number of passes) is the result of the draft schedule from the outside of FIG. 2S1, and is TISO element (former schedule transfer temperature), TCHU element (former schedule intermediate temperature), T1AS element (former schedule 1 reduction temperature before). And KT (i) (for the inlet side air-cooling temperature gradient in the i-pass, it is the temperature calculated at the first standard speed, time setting.

First, S4-11, S4-6, S of FIG.
The contents of the temperature determination method in 4-15 are shown below. In the schedule calculation for each path, it is checked whether the path currently being calculated has a regulated temperature, and if the regulated temperature exists, it is determined whether the temperature is within the upper and lower limits, and the process branches. When the number of current passes in S4-11 is equal to the number of regulated intermediate passes (NT-NC + 1), the regulation temperature upper limit check TCHU (upper limit value) <Tin (current path entrance side surface temperature), jump to S4-12, and regulate. If the temperature lower limit check TCHU (lower limit)> Tin (current pass inlet side surface temperature), jump to S4-12. In other cases, it is possible to secure the intermediate regulation temperature S4-
Proceed to the process of 13. When the number of current passes in S4-6 and S4-15 = number of last passes (NT), the upper and lower limit check in the case of no intermediate regulation temperature in S4-6 TLAS (upper limit value) <Tin (current surface temperature on the inlet side of the current pass) If so, jump to S4-8. If TLAS (lower limit value) <Tin (surface temperature on the entrance side of the current path), jump to S4-8. At S4-15, upper and lower limit check without intermediate regulation temperature TLAS ( If the upper limit value <Tin (surface temperature on the entrance side of the current path), jump to S4-15. If TLAS (lower limit value) <Tin (surface temperature on the entrance side to current path), jump to S4-16. (Last path regulation temperature can be secured) S4-7 or S4-1 as the last path regulation temperature OK
Proceed to the process of 6. (1) How to use the parameters ΔTCHU, ΔTISO, and DTIC When calculating the average inlet side air-cooling time change amount per pass when there is an intermediate temperature regulation and when the intermediate temperature judgment is NG, the parameter Δ TCHU, TISO, and DTIC are used.

[Equation 1] (2) How to use the parameters ΔTLAS, ΔTISO, DTIL When calculating the average inlet side air-cooling time change amount per pass when there is no intermediate temperature regulation and when the one-roll-down pre-temperature determination is NG, Parameter △ TLAS, TISO, DTIL
To use.

[Equation 2] (3) How to use the parameters ΔTLAS and DTCL When calculating the average inlet-side air-cooling time change amount per pass when there is an intermediate temperature regulation and when the one-roll-down pre-temperature judgment is NG, the parameter ΔTLAS is used. , DTCL is used.

(Equation 3)

Next, S4-12, which is the process from the intermediate temperature determination NG, will be described. If the intermediate temperature is judged to be NG, it is first checked whether or not the biting temperature at the start of rolling can be corrected, and the rolling start temperature is changed within the correctable range. Next, a time change process is equally performed for the temperature drop amount from the start to the intermediate pass, and a preparatory process for recalculating the temperature schedule for achieving the target intermediate temperature is performed. Regulation intermediate temperature The deviation amount of the target temperature vs. the original schedule temperature is calculated. Intermediate pass aim value deviation temperature: △ TCHU = TCHU (original) -TCH
Uaim Corrected bite temperature (rolling start temperature) is determined under the following conditions. I. When the trapping temperature control material is used (regardless of the actual temperature at the end of rough rolling), the trapping temperature of the original schedule is shifted by the intermediate temperature deviation, and a check is made within the control trapping temperature upper and lower limits. B-1. TLS (lower limit)> TISO (original)-△ TCHU
If (lower limit is exceeded) TISO (new) = TLS (lower limit) a-2. If TLS (upper limit) <TISO (original) -ΔTCHU (when upper limit is exceeded) TISO (new) = TLAS (upper limit) A-3. If other than the above (even if the shift is within the regulated bite temperature), TISO (new) = TISO (original) -ΔTCHU b. When other than the trapping temperature control material b-1. Rough rolling finish actual temperature is present (rough rolling has already been completed)
And when there is no room to shift the finishing start temperature. That is, the rough rolling finish temperature: TISOE <TISO (original) -ΔTCHU
Then TISO (new) = TISOE b-2. Other than the above (bite temperature can be changed)
Then, TISO (new) = TISO (original) -ΔTCHU Corrected bite temperature Calculate the deviation amount between the original schedule temperature and the corrected value. Starting path aim value deviation temperature: △ TISO = TISO (original) -TIS
O (New) Calculate the temperature drop correction amount from the bite (start) to the intermediate pass. Temperature drop correction amount: △ TIC (℃) = △ TCHU- △ TISO Calculate the average inlet side air cooling time change amount per pass

[Equation 4] However, KT (i) (° C / s): Inlet-side air-cooling surface temperature gradient in the i-pass, when the inlet-side air-cooling differential calculation is first performed for each pass (temperature drop / air-cooling time) N: Initial biting Number of passes from pass to intermediate pass (NT-NC
+1) With THFLAG = 2, Δtt = ΔtIC, recalculate from the inlet path and transfer temperature distribution of the secondary schedule calculation. Also,

(Equation 5)

Further, S4-8, which is the processing from the temperature NG before 1 reduction without intermediate temperature regulation, will be described below. If the temperature is judged to be NG by 1 pressure reduction, first,
It is checked whether the bite temperature at the start of rolling can be corrected and the rolling start temperature is changed within the range that can be corrected. Next, a time changing process is equally performed for the temperature drop amount from the start to the last pass, and a preparatory process is performed to recalculate the temperature schedule for achieving the target temperature before one reduction. Regulation 1 temperature before reduction Calculate the deviation amount of the target temperature vs. the original schedule temperature. 1 Target temperature deviation before pass: Temperature deviation: TLAS = TLAS (original)
-TLASaim Corrected bite temperature (rolling start temperature) is determined under the following conditions. I. When the trapping temperature control material is used (regardless of whether or not there is a rough rolling finish actual temperature), the trapping temperature of the original schedule is shifted by the intermediate temperature deviation, and a check is made within the regulation trapping temperature upper and lower limits. B-1. If TLS (lower limit)> TISO (original) -ΔTLAS (lower limit exceeded) TISO (new) = TLAS (lower limit) B-2. If TLS (upper limit) <TISO (original)-△ TLAS (upper limit exceeded), TISO (new) = TLAS (upper limit) a-3. If other than the above (even if the shift is within the regulated bite temperature), TISO (new) = TISO (original) -ΔTLAS b. When other than the trapping temperature control material b-1. The rough rolling finish temperature is available (rough rolling is already completed) and there is no room to shift the finishing start temperature. That is, if rough rolling finish temperature: TISOE <TISO (original) -ΔTCHU, then TISO (new) = TISOE b-2. If other than the above (bite temperature can be changed): TISO (new) = TISO (original)-△ TLAS Corrected bite temperature Calculate the deviation amount between the original schedule temperature and the corrected value. Starting path aim value deviation temperature: △ TISO = TISO (original) -T
ISO (New) Calculate the temperature drop correction amount from the bite (start) to the last pass. Temperature drop correction amount: △ TIL (℃) = △ TLAS- △ TISO Calculate the average inlet side air cooling time change amount per pass However, KT (i) (° C / s): Inlet-side air-cooling surface temperature gradient in the i-pass, when the inlet-side air-cooling differential calculation is first performed for each pass (temperature drop amount / air-cooling time) N: Initial biting The number of passes from the pass to the last pass (NT) THFLAG = 3, Δtt = ΔtIL is recalculated from the inlet pass and transfer temperature distribution of the secondary schedule calculation.

Lastly, S4-15, which is the process from the temperature NG before one reduction with intermediate temperature regulation, will be described.
When there is an intermediate temperature regulation, and if the temperature before the first reduction is NG, the schedule from the initial bite to the intermediate regulation pass is considered as a fix, and the non-uniform delay between the passes from the intermediate to the last pass is considered. Correct the temperature schedule so that there is no. The deviation amount between the temperature before the regulation 1 reduction and the target temperature vs. the original schedule temperature is calculated. 1 Target temperature deviation before pass: Temperature deviation: TLAS = TLAS (original)
-TLASaim Calculate the temperature drop correction amount from the intermediate pass to the last pass. Temperature drop correction amount: DTCL (℃) = △ TLAS Calculate the average inlet side air cooling time change amount per pass However, KT (i) (℃ / s): Inlet-side air-cooling surface temperature gradient in the i-pass, when the inlet-side air-cooling differential calculation is first performed for each pass (temperature drop amount / air-cooling time) N: Intermediate regulation pass To the last pass (NT-
NC +2) With THFLAG = 4, Δtt = ΔtCL, recalculate from the next pass of the intermediate pass of the secondary schedule calculation.

FIG. 7 shows a deviation histogram between the target temperature and the actual temperature with the prior art. In the prior art, the deviation σ = 7.5 ° C., whereas in the present invention σ = 3.
It has improved to 2 ° C.

FIG. 8 shows the difference in temperature schedule between the prior art and the present invention. Only the temperature path regulated in the prior art has a small deviation from the target value, and the temperature is changed only in the path immediately before that. Although adjusted, in the present invention, the actual temperature along the target temperature is ensured in all the paths with a smooth temperature drop over all the paths.

Further, FIG. 9 is a time chart showing whether the material to be rolled is in a roll bite or idle between passes. Comparing the two, in the prior art, there is a large variation in the metal off time between passes, and rolling is rapid. It can be seen that, while the paths that are gently delayed are non-uniform, the present invention provides smooth time distribution with uniform inter-path time.

[00033]

As described above, according to the temperature control method for thick plate rolling of the present invention, the rolling temperature schedule for all passes is determined in advance according to the regulated temperature. From this, the operator can accurately recognize the timing to start rolling, and the target value of the rolling temperature schedule for all passes is clear, and the speed and waiting time are automatically calculated from the difference between the planned temperature and the actual temperature. Since the adjustment is performed, the temperature waiting that is non-uniform and greatly varies between passes can be eliminated, and smooth rolling can be realized from the start to the end of rolling. Therefore, not only the regulated temperature can be accurately ensured, but also unpredictable waiting time between passes during rolling is eliminated, so that the rolled material can be extracted from the heating furnace at an appropriate timing.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a control system for realizing a thick plate rolling method according to the present invention.

FIG. 2 is a flowchart showing an outline of a process for realizing pass schedule calculation on the premise of temperature-controlled rolling in plate rolling according to the present invention.

FIG. 3 is a flowchart showing a process for setting an initial biting temperature.

FIG. 4 is a flowchart showing how to perform the processes of S4 to S14 of FIG. 2 according to each temperature constraint condition.

FIG. 5 is a schematic diagram showing time element division for each path in the embodiment of the present invention.

FIG. 6 is a diagram showing calculation results in the second pass from the initial stage in the embodiment of the present invention.

FIG. 7 is a diagram showing a deviation histogram between the target temperature and the actual temperature between the related art and the present invention.

FIG. 8 is a diagram showing a difference in temperature schedule between the conventional technique and the present invention.

FIG. 9 is a time chart showing whether the material to be rolled is in a roll bite or idle between passes according to the related art and the present invention.

[Explanation of symbols]

 1 Process Computer 2 Business Computer 3 Finishing Plant Controller 4 Rolling Material 5 Radiation Thermometer 6 Table Roll 7 Work Roll 8A Mill Motor 8B Motor Current Controller 9 Table Motor 10 Load Cell 11 Backup Roll

Claims (1)

(57) [Claims] 1. When rolling a sheet material using a reversible rolling mill, when the rolling is performed while adjusting the temperature of the material in the rolling process for the purpose of controlling the material quality, the actual elapsed time during rolling, Predictive calculation of the steel plate temperature from the rolled plate thickness and rolling load, and the estimated temperature drop amount after the next pass are calculated, and the rolling speed for each pass and the time between passes are operated to achieve the preset rolling temperature. A method for controlling temperature in plate rolling, comprising: