JP2008114230A - Method for controlling temperature of rolling material in hot rolling, and hot rolling method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling the temperature of a rolling material in hot rolling, by which method, the increase of the load to a process computer to be caused by frequent re-calculating operations can be suppressed, and the transportation of the rolling material during rough rolling can be carried out while avoiding the lead, delay, and disturbance of the transportation timing with respect to the timing scheduled by the mill pacing control as much as possible, and further the deviation of the temperature of following rolling materials from an allowable range and the generation of defective quality of the rolling materials to be caused by the deviation can be suppressed. <P>SOLUTION: The actual temperature of the rolling material 1 before extracting it from a heating furnace 10 is compared with a target extracting temperature of the material. When the actual temperature is higher than the target temperature, the rolling speed in part of rough rolling of the rolling material 1 is reduced. Further, when the actual time that the rolling material has arrived at the entrance side of principal equipments located on the upstream side than the position to reduce the rolling speed of the rolling material 1 to be reduced in the rolling speed or at the respective principal equipments themselves has delayed compared with the expected arrival time predicted before extracting the rolling material from the heating furnace 10, the speed reduction in part of rough rolling of the rolling material is reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a temperature control method for a material to be rolled in hot rolling, and a hot rolling method using the same.

  In hot rolling, generally, a slab-like metal material produced by continuous casting or ingot-making / bundling is heated to several hundred to several hundreds of degrees Celsius in a heating furnace and then placed on a hot rolling line. It is a series of processes of extracting and winding thinly and winding it into a coil shape by rotating the roll while pinching with a pair or a plurality of pairs of rolls.

  FIG. 1 shows an example of a conventional hot rolling line 100. A metal material 1 having a thickness of 150 to 300 mm (hereinafter referred to as a material to be rolled) 1 heated to several hundred to several hundreds of degrees Celsius by the heating furnace 10 is rolled to a thickness of 0.8 to 25 mm by a roughing mill 12 and a finishing mill 18. And thinly extended into a metal plate.

  In the case of the hot rolling line 100 shown in FIG. 1, the rough rolling mill 12 has three groups of R1, R2, and R3, but the number of bases is not necessarily limited thereto. In addition to one or two, the most common one is four, and the one with a large number is up to six. In the case of the most general four units, there are many types called 3/4 continuous (three quarters) in which one of the four units is reciprocally rolled, and the remaining rolling mill performs unidirectional rolling. However, three of the four aircraft are not limited to the one-way type, and for example, as shown in FIG. Some have a width press 9 installed immediately upstream of the roughing mill 12.

  In the case of the hot rolling line 100 shown in FIG. 1, the number of rolling mills (stands) constituting the finish rolling mill 18 is seven of F1 to F7, but there are six.

  Although there are differences in these various radixes, the rough rolling machine 12 performs rough rolling 6 times or 7 times in general by reciprocating rolling or unidirectional rolling or both, and the material 1 to be rolled after rough rolling. To the subsequent finishing mill 18. Each rolling in the rough rolling is also referred to as each rolling pass, and rolling a plurality of times such as 6 times or 7 times is referred to as rolling in 6 passes or 7 passes.

  The finishing mill 18 takes the form of a tandem rolling mill that simultaneously rolls a high-temperature rolled material 1 of several hundred to several hundreds of degrees Celsius with a plurality of rolling mills, but is not a finishing tandem rolling mill, but simply “finishing”. Often referred to as a “rolling mill”. In the figure, 2 is a roll, 13, FIE is an edger roll, 15 is a finishing entry thermometer, 21 is a finishing delivery thermometer, 22 is a finishing delivery thickness gauge, 23 is a run-out table, 24 is a coiler, 25 is A coiler inlet side thermometer, 50 is a control device, 70 is a process computer, and 90 is a business computer.

  As shown in FIG. 1, a hot rolling method of repeating a series of operations of rolling a material to be rolled by a finish rolling mill 18 and rolling the next material to be rolled at a certain time interval. This is called batch rolling. On the other hand, in some cases, the materials to be rolled are joined and finish-rolled, which is called continuous hot rolling or endless rolling, but batch rolling is more common.

  By the way, in the hot rolling line 100, a large number (more than one hundred) of table rollers (not shown) are installed between other rolling mills (stands) except between the stands of the finish rolling mill 18. The rolled material 1 is conveyed.

  By the way, when extracted from the heating furnace 10, an oxide layer (hereinafter referred to as scale) is formed on the front and back surfaces of the high-temperature rolled material 1 heated to several hundred to several hundreds of degrees Celsius as described above. is doing. In addition, since the rolled material 1 is exposed to the atmosphere at a high temperature even in the process of being rolled and thinned and lowered in temperature by heat radiation, new scales are generated on the front and back surfaces of the rolled material 1. For this reason, on the entry side of each rolling mill in the rough rolling mill 12, descaling is performed by spraying high-pressure water inside and outside 10 to 30 MPa on the front and back surfaces of the material 1 to be rolled as the supply pressure from the pump. A device 16 is installed to remove the scale.

  Moreover, although not shown in figure, since each roll 2 contacts a hot material to be rolled, it is cooled with cooling water.

  In FIG. 1, reference numeral 14 denotes a crop shear, which cuts and removes the crop at the leading end of the material 1 to be rolled (the irregularly shaped portion at the leading end of the material 1 to be rolled) before finish rolling. 18 is shaped into a substantially rectangular planar shape that is easy to be smoothly bitten into 18.

  In general, in hot rolling, according to various customer-requested specifications for rolled metal sheet products, for each material to be rolled, the finish side temperature is ensured from the viewpoint of ensuring mechanical properties and preventing surface quality defects. The allowable range is defined.

  In metallurgy, it is optimal to control the temperature of the material to be rolled within an allowable range in any one of a plurality of finish rolling mills. Since it is very difficult to measure the temperature of the material being rolled in the rolling process, instead, representatively, the temperature of the material to be rolled on the exit side of the finish rolling mill, that is, the finish side An allowable temperature range is determined, and various temperature controls are performed so as to be within the range.

  As described above, in order to keep the finish side temperature within an allowable range, it is easiest to think about the upper and lower limits in terms of the control of the temperature of the material to be rolled before the start of finish rolling. It is also the method that is being carried out.

  In order to control the finish side temperature within an allowable range, a finish side thermometer 21 is installed in the hot rolling line 100 shown in FIG. 1, and the temperature of the material to be rolled before the finish rolling is started. In order to perform control to keep the value within the upper and lower limits of the control, a finishing input side thermometer 15 is installed.

  Furthermore, as a method of controlling the temperature of the material to be rolled before finishing rolling, the target extraction temperature before extracting the material to be rolled from the heating furnace is set as a lower limit, and if the lower limit is exceeded, extraction is performed. Many methods are used.

  The upper limit of the extraction temperature may be determined depending on the material of the material 1 to be rolled, but if not, 1350 ° C. or less from another viewpoint such as suppression of yield reduction due to increase in scale loss and durability of heating furnace equipment. It is usually stipulated.

  The upper and lower limits of the finishing delivery temperature, finishing entry temperature, and extraction temperature described above are determined in advance for each category such as the material and dimensions of the material to be rolled.

  By the way, as is the case with the hot rolling line 100 shown in FIG. 1, generally, the hot rolling line is 300 meters from the heating furnace to the finishing mill entry side, while the material to be rolled. The length of the steel sheet is at most a few dozen meters in the heating furnace and at most 100 meters even after rough rolling, and a plurality of materials to be rolled can exist simultaneously on the hot rolling line.

  Therefore, in order to improve productivity, in rough rolling, a final rolling mill (a hot rolling line 100 in FIG. 1 as an example in the case of the hot rolling line 100 in FIG. 1) is selected as R3. ) Is not extracted from the heating furnace 10 after the completion of the rolling in step), but the rolling in the final rolling mill (R3 in the example of the hot rolling line 100 in FIG. 1) is completed. A method is generally employed in which the material to be rolled 1 is extracted one after another without waiting, and a plurality of materials to be rolled are flow-rolled.

  At that time, the time interval for extracting the material 1 to be rolled from the heating furnace 10 does not collide with the material to be rolled anywhere on the hot rolling line, and the next material to be rolled is rolled after a certain material is rolled. Various settings can be changed until the start of rolling in each equipment on the hot rolling line (width press 9, roughing mill 12, finishing mill 18, runout table 23, coiler 24, etc.). As a method for adjusting to the shortest time interval that can ensure a proper interval, for example, a mill pacing control method as shown in Patent Document 1 is often used.

  This mill pacing control method is performed by each equipment on the hot rolling line (width press 9, roughing mill 12, finishing mill 18, runout table 23, coiler 24, etc.) and a table roller in between. Assuming that the conveyance speed of the rolled material is processed according to a predetermined conveyance speed pattern, for example, after rolling a certain material to be rolled 1 with F1 which is the first rolling mill of the finish rolling mill 18, In the shortest time interval that can secure the time interval necessary for changing the setting of each rolling mill until the next material to be rolled at F1 is started, After the rolling of the rolled material at F1 which is the first rolling mill of the finish rolling mill 18, the above-described next rolled material is adjusted to adjust the time required to start rolling the next rolled material at the same F1. The time for extraction from the heating furnace 10 is determined in advance. In the process computer 70, it determines by calculation for every to-be-rolled material, and when that time comes, it controls to actually extract the above-mentioned next to-be-rolled material from a heating furnace (predetermined conveyance) (See Figure 3 below for speed patterns).

  Here, as in the above-described example, the actual rolling material is finish-rolled at the shortest time interval that can secure the time interval necessary for the setting change of each rolling mill. After the completion of rolling by F1 which is the first rolling mill of the machine 18, the time for extracting the next rolled material from the heating furnace 10 is adjusted in order to adjust the time required for starting the rolling of the next rolled material at the same F1. What is determined is only an example. Instead of this, in addition to the setting change of the width press 9, the setting change of any rolling mill of the rough rolling mill 12, the setting change of the run-out table 23, the coiler 24 After the material has passed through the actual equipment at the shortest time interval that can secure the time interval necessary for setting change, etc., the next material to be rolled reaches the equipment. Time to extract the next material to be rolled from the furnace 10 to adjust the time required to If it decides to also.

  Therefore, during the operation of the hot rolling line, in addition to the width press 9 in the process computer 70, the rolling presses in the rough rolling mill 12, the finishing rolling mill 18 in accordance with the above-mentioned mill pacing control. , Run-out table 23, coiler 24 such as entry and exit of major equipment, or arrival time of each rolled material to and from these major equipment itself, and entrance and exit of major equipment or The process in which the passage end time of each material to be rolled in these main facilities is calculated by time is repeated.

  Now, in order to keep the finishing delivery temperature within the allowable range, further controlling the temperature of the material to be rolled before finishing rolling, and further controlling the temperature of the material to be rolled before finishing rolling is started. In addition, the target extraction temperature before extracting the material to be rolled from the heating furnace 10 is determined, and when it reaches that temperature, the temperature is controlled by the temperature control method of the material to be rolled in hot rolling, and then, The mill pacing control method for improving productivity in the hot rolling affects each other.

  That is, if the temperature of the material 1 measured with the finishing entry thermometer 15 exceeds the upper limit of the temperature of the material before the start of finish rolling, as shown in FIG. The material to be rolled may be put on standby at the entry side of the finish rolling mill 18 by oscillation or the like, and then the arrival of each material to be rolled 1A, 1B to the entry side and the exit side of each major facility thereafter. The time and the passage end time of each material to be rolled 1A, 1B on the entry side and the exit side of each major facility will be delayed from the time scheduled in the mill pacing control.

  In the above-mentioned Patent Document 1, not only the error in schedule calculation due to the difference between the predicted temperature and the actual temperature as described above but also the accumulation of errors in the conveyance prediction model on the side of the mill pacing control, etc. The time at which each rolled material arrives at the entry side and the exit side, and the passage end time of each rolled material at the entry side and the exit side of each major facility, is the time that is scheduled by mill pacing control. As a result, as in the case where the temperature of the material to be rolled exceeds the upper limit of the temperature of the material to be rolled before finishing rolling, The problem described in the following occurs.

  The problem is that when the above situation occurs, the mill pacing control must be recalculated so that the extraction time of the material to be extracted next from the heating furnace is delayed by that delay. Inevitably, if this is not reflected in the heating temperature control of the material to be rolled in the heating furnace 10, the material to be rolled is overheated. 10, after reaching the finishing input thermometer 15 through rough rolling, it has exceeded the upper limit of the temperature of the material to be rolled before finishing rolling, waits for oscillation again, and then the heating furnace The extraction of the material to be rolled extracted from No. 10 is delayed, and the vicious cycle of overheating again is repeated.

  Accordingly, various methods have been proposed as a method for controlling the temperature of the material to be rolled without delaying the start of finish rolling.

  For example, in Patent Document 2, during rough rolling, the temperature drop of the material to be rolled per unit time due to heat transfer from the material to be rolled to the roll is the same in the latter half of the rough rolling in which the plate thickness of the material to be rolled becomes thin. Utilizing the fact that the plate thickness is larger than that of the first half of rough rolling, as shown in FIG. 3A, the speed of the material to be rolled is delayed in the latter half of rough rolling to extend the required time. As shown in (b), the speed of the material to be rolled is increased in the first half of the rough rolling to shorten the required time, and is delayed in the second half to extend the required time, so that the finish rolling start time is kept constant and the rough rolling is performed. We propose a method to increase the temperature drop.

  However, in Patent Document 2, the temperature of the material to be rolled is actually measured at the entry side of the final rolling mill R3 among the plurality of rough rolling machines 12, and the subsequent rolling of the material to be rolled is performed according to the result. The method of adjusting the speed and the conveyance speed is given as an example.

  However, if the temperature of the material to be rolled 1 is actually measured after extraction from the heating furnace 10 and the rolling speed and the conveying speed of the material to be rolled are changed according to the results, The arrival time of each rolled material on the side and the outlet side, and the end time of passage of each rolled material on the entry side and exit side of each major facility were frequently scheduled by mill pacing control. Every time it is advanced, delayed or disturbed with respect to the time, the scheduled extraction time of the material to be rolled next to be extracted from the heating furnace 10 must be recalculated, and the load on the process computer 70 increases. To do.

  Moreover, since there are a plurality of materials to be rolled during rough rolling as described above, the preceding rolled material is R3, the following rolled material is R2, and the next rolled material is R1. If recalculation is performed every time it arrives, the load of the process computer 70 will finally increase.

  In Patent Document 3, as a result of changing the speed of a certain material to be rolled, the arrival of the material to be rolled reaches the entry side and the exit side of each major facility thereafter, or the principal facility itself. When the time and the end of passage of the material to be rolled on the entry and exit sides of each major facility, or the major facility itself, are later than the time scheduled for mill pacing control Proposes a method for forcibly waiting each material to be rolled upstream thereof at the entry side of each major facility such as a rolling mill that is scheduled to pass next.

  However, even in this method, the problem of an increase in the load of the process computer 70 accompanying the recalculation remains as it is, and separately, the temperature of each subsequent rolled material upstream of a certain rolled material is appropriate. Even if it exists, since it is made to wait forcibly, the problem that the case where it falls below the minimum of the temperature of the to-be-rolled material before the start of finish rolling comes out newly arises as a result. Then, there is no means for heating the material to be rolled on the entrance side of the finishing mill, or even if the heating capacity is not sufficient, the temperature is out of the allowable range. The material becomes poor in quality and leads to a decrease in product yield.

  Patent Document 4 also proposes to keep the temperature after rolling constant by reducing the speed of each stand.

JP-A-62-289308 JP 11-277126 A Japanese Patent Laid-Open No. 06-299321 JP 59-130602 A

  However, as described above, delaying the conveyance of the material to be rolled during rough rolling and the entire rolling speed causes various operational problems such as an increase in the load on the process computer and a decrease in product yield due to poor quality. .

  The present invention has been made to solve the above-mentioned conventional problems, and the conveyance of the material to be rolled during rough rolling is controlled by mill pacing while suppressing an increase in the load of the process computer accompanying frequent recalculation. In addition to being able to avoid as early as possible, lagging or disturbing the scheduled time, it is possible to suppress the occurrence of quality defects associated with the temperature of each subsequent rolled material being outside the allowable temperature range. Another object of the present invention is to provide a temperature control method for a material to be rolled in hot rolling.

  In order to solve the above problems, the present invention, in hot rolling, as shown in the first half of FIG. 4, compared the actual temperature before extracting the material to be rolled from the heating furnace with the target extraction temperature, When the actual temperature before extracting the material to be rolled from the heating furnace is higher, the speed of a part of the rough rolling of the material to be rolled is reduced.

  Furthermore, as shown in the second half of FIG. 4, the present invention further provides a material to be rolled that has been decided to reduce the speed on the entry side of the main equipment on the upstream side of the speed reduction, or the respective main parts. When the actual time at which the material to be rolled reaches the equipment itself is slower than the estimated time of arrival predicted before extraction from the heating furnace, a part of the speed reduction of the rough rolling of the material to be rolled It is intended to reduce this.

  The present invention is also a hot rolling method using them.

  According to the present invention, while suppressing an increase in the load of the process computer accompanying frequent recalculation, the conveyance of the material to be rolled during rough rolling is accelerated with respect to the time scheduled for the mill pacing, While making it possible to avoid delays and disturbances as much as possible, it is possible to suppress the deviation of the temperature tolerance of each subsequent rolled material and the occurrence of quality defects associated therewith.

  Both the first embodiment and the second embodiment described below should be understood with reference to FIG. 4 as appropriate.

(First embodiment)
In the present invention, when the actual temperature before extracting a certain rolled material 1 from the heating furnace 10 is compared with the target extraction temperature, the actual temperature before extracting the rolled material from the heating furnace is higher In addition, the speed of a part of the rough rolling pass of the material to be rolled is reduced.

  Here, decelerating means that, before extracting the material 1 to be rolled from the heating furnace 10, the speed is lower than the partial rolling speed that was originally planned in the process computer 70. The schedule computer reschedules within the process computer 70 to change the speed of some of the rough rolling.

  For that purpose, the method of extending the required time by delaying the speed of the material to be rolled as shown in FIG. 3 (a) described above in the latter half of the rough rolling, or the speed of the material to be rolled as shown in FIG. 3 (b). In the first half of rough rolling, the required time can be shortened and the required time can be shortened in the latter half, and the required time can be extended by delaying, or another method can be used.

  In this case, it is important that the mill pacing also calculates the arrival time of each major facility itself or its entry and exit sides based on the changed speed. In this way, the mill pacing only needs to be calculated according to the planned conveyance pattern from the beginning, such as errors in the conveyance prediction model on the mil pacing control side, or catching on a side guide (not shown), etc. As long as there is no delay from the scheduled transfer pattern due to troubles, the increase in the load on the process computer due to frequent recalculation can be suppressed to a considerable extent.

  In this way, the rolling speed such as the peripheral speed of the roll 2 when rolling the material 1 to be rolled in a rough rolling mill 12, or other times (between the heating furnace 10 and the width press 9, the width Re-scheduling to reduce the conveyance speed of the material to be rolled between the presses 9 to R1, between R1 and R2, and between R2 and R3 from those originally planned is performed from the heating furnace 10. Before extracting the rolled material, it can be done while avoiding that the conveyance of the material to be rolled during rough rolling is accelerated, delayed or disturbed as compared to the time scheduled for mill pacing control. As a result, it is also important to be able to suppress the occurrence of temperature defects in the subsequent rolled materials and the associated quality defects.

  The target extraction temperature is determined by the actual dimensions of the material to be rolled at the slab stage and the target product dimensions. The rough rolling schedule (thickness of the material to be rolled and roll peripheral speed in each rough rolling pass) In general, the finish entry side temperature of the material to be rolled is determined so as to substantially coincide with the target finish entry side temperature.

  Therefore, when the actual temperature before extracting a certain to-be-rolled material from the heating furnace 10 is higher than the target extraction temperature, it is assumed that the finish input side temperature record is also higher than the target finish input temperature. .

  Therefore, in such a case, the speed of a part of the rough rolling pass of the material to be rolled is reduced. Here, the speed of a part of the rough rolling pass of the material to be rolled includes not only the speed when the material to be rolled is actually rolled by the roll but also the speed when the material is being conveyed. It is.

  Then, since the contact time between the relatively low temperature roll and the relatively high temperature material to be rolled becomes longer, the temperature of the material to be rolled is initially planned due to heat transfer between the roll and the material to be rolled. Compared to rolling at the speed that was done.

  In addition to this, the effect of cooling the material to be rolled by descaling water sprayed on the material to be rolled in a rolling pass or the like at which the rough rolling speed has been reduced also contributes to the fact that the speed is reduced. .

  Since the temperature drop rate (temperature drop per unit time) due to heat transfer between the roll and the material to be rolled is larger than the temperature drop rate due to natural air cooling of the material to be rolled, a part of the rough rolling pass of the material to be rolled Decreasing the speed of the steel sheet requires less reduction in rolling efficiency than waiting for the material to be rolled on the entry side of the finishing mill 18.

(Second embodiment)
In addition, a part of the rough rolling pass of the material to be rolled is set to a lower speed than the originally planned speed in the process computer 70, and the width of the material to be rolled is reset. Recalculate the estimated time of arrival at each major facility, such as the rough rolling mill 12 such as R1, R2,. Actually, when the material to be rolled 1 arrives at the entry side of each major facility or each major facility itself, the actual time is extracted from the heating furnace 10 for some reason. When the predicted arrival time (scheduled time after the recalculation) is reached, it is preferable that the rough rolling of the material 1 to be rolled is preferably performed corresponding to the air cooling temperature drop for the delayed time. Reduce the deceleration of the speed of part of the path Was also not only the time period, there is the effect if reduce the deceleration worth even a little).

  As a result, conveyance of the material to be rolled during rough rolling is not completed, the rough roll mill side guide (not shown) is not established, the table roll and the material to be rolled slip, and factors on the mill pacing control side, that is, the predicted temperature and the actual temperature. Even if it is delayed due to errors in schedule calculation due to differences from the above, errors in the conveyance prediction model, etc., only a part of the rough rolling pass of the material to be rolled corresponds to the air cooling temperature drop for the delayed time. Since the deceleration of the speed is reduced, it is possible to suppress the occurrence of a temperature defect outside the allowable temperature range of each subsequent rolled material and the accompanying quality defects.

  In the two embodiments described above, the recalculation of the mill pacing control is not completely denied, but the first rolling mill F1 of the finishing mill entry side thermometer 15 and the finishing mill 18 is covered. The object of the invention can be achieved by suppressing the frequency anyway, for example, only when the tip of the rolled material 1 has reached.

  Examples of the present invention will be described below with reference to the drawings as appropriate, taking as an example the case where the present invention is applied to the hot rolling line 100 shown in FIG.

  In the hot rolling line 100, as shown in FIG. 1, a heating furnace 10, a rough rolling mill 12 (R1 to R3), a finishing rolling mill 18, a coiler 24, and the like are sequentially arranged according to the conveyance direction A of the material 1 to be rolled. As described above, each facility is installed and controlled by a command from the control device 50.

  Each time a single rolled material 1 is extracted from the heating furnace 10, the process computer 70 applies a part or all of the rolled material 1 in the plurality of heated furnaces 10 in the slab-like stage. From the actual results of the dimensions of the rolled material, the target product dimensions, etc., to the range of restrictions on equipment capacity, such as the rolling load upper limit of the roughing mill 12 and the finishing mill 18 and the load torque of the motor (not shown) that drives the roll In consideration of the fit, the planned thickness after rolling in each pass of each roughing mill 12, the roll gap (rolling position), the roll peripheral speed, etc., and the planned rolling in each pass of the finishing mill 18 The plate thickness, roll gap (rolling position), roll peripheral speed, etc. are determined by either table value index or model calculation. The determined value is sent to the control device 50 as a command value.

  The process computer 70 also schedules after rolling in each pass of each roughing mill 12, scheduled plate thickness after rolling, roll gap (rolling position), roll peripheral speed, etc., and in each pass of the finishing mill 18. After the extraction of the material 1 to be rolled from the heating furnace 10 from the plate thickness, roll gap (rolling position), roll peripheral speed, and the like, the arrival times of the main facilities on the entry and exit sides are predicted and calculated. The result of this prediction calculation is hereinafter referred to as a carrier line.

  Furthermore, the process computer 70, for each rolled material 1 in the heating furnace 10, when charging the heating furnace 10, the actual charging temperature measured by a heating furnace inlet side thermometer (not shown) and at a certain cycle. Based on the measured atmospheric temperature of each zone in the heating furnace 10 measured with a thermometer in the heating furnace (not shown), the temperature is calculated by a method such as a differential model whose outline is shown in FIG. To do.

  The process computer 70 then extracts the material to be rolled 1 from the heating furnace 10 for the material 1 before extraction, such as the next extraction schedule or the next extraction schedule from the heating furnace 10. The actual temperature T_actual and the target extraction temperature T_th are compared as in the following equation (1) to calculate the extraction temperature difference ΔT_F.

    ΔT_F = T_real-T_th (1)

  Here, the target extraction temperature T_th is the pass of each rough rolling mill 12 calculated as described above when the material to be rolled 1 is extracted from the heating furnace 10 at the target extraction temperature. In this case, when the rolling is performed according to the planned plate thickness after rolling, roll gap (rolling position), roll peripheral speed, etc., and the conveying line, the finishing side temperature is generally the target finishing side temperature. It is determined as follows. Specifically, when an extraction temperature and a predetermined rough rolling schedule (thickness of the material to be rolled and roll peripheral speed in each rough rolling pass) are input, the material to be rolled such as a known difference method or Newton method is used. By preparing a temperature drop model during rolling and a natural air cooling temperature drop model during rolling and transport, a function for obtaining the finish input temperature is prepared, and the target finish input temperature is determined in the function. It can be obtained as the extraction temperature determined at the time.

  Moreover, since it is a timing which calculates (DELTA) T_F, I want to obtain | require extraction temperature difference (DELTA) T_F at the timing close | similar to an extraction time as much as possible, Therefore The slab-shaped to-be-rolled material 1 is provided in the most extraction side in the heating furnace 10 A timing at which the temperature of the slab-shaped rolled material 1 is reached and the temperature of the slab-shaped rolled material 1 no longer changes so much, for example, next, is extracted. It is preferable that the calculation is performed at the timing when it is determined.

  Next, when the extracted temperature difference ΔT_F obtained earlier is larger than 0, the process computer 70 determines a rough rolling pass to be decelerated and sets the decelerating rate α (0 <α <1, 1 is not decelerated). calculate. Exactly, not only the speed when the material 1 is actually rolled by the roll 2 but also the speed when it is conveyed can be the target of deceleration.

  Here, the deceleration rate α can be obtained by the following equation (2) from the extracted temperature difference ΔT_F, the speed setting V_ setting of the rough rolling pass to be decelerated, and the temperature drop rate R in the rough rolling pass. .

    α = k1 k2 R / (k1 k2 R + V_ installation ΔT_F) (2)

  In addition, k1 in Formula (2) is a coefficient, and can be easily derived from the rolling schedule (the thickness of the material to be rolled and the roll peripheral speed in each rough rolling pass) and the roll radius. Further, k2 is a coefficient and represents how many differences the extraction temperature difference corresponds to on the roughing mill delivery side or finishing input side. This k2 changes the extraction temperature in the same rolling schedule, and calculates the temperature drop model during rolling of the material to be rolled and the natural air cooling temperature drop model during rolling and conveyance, so that rough rolling against the change in extraction temperature It can be obtained as a rate of change in the temperature of the material to be rolled on the machine exit side or the finish entry side, or can be stratified for each rolling schedule and experimentally obtained as a table value.

  Further, as a method of determining a rough rolling pass or the like to be decelerated, for example, for each rolling pass, the deceleration rate α is obtained by the above equation (2), the extension time Δte is obtained by the equation (3), and Δte is the smallest. However, the present invention is not limited to this.

    Δte = (1−α) / α × L / V_ setting (3)

  In Formula (3), L is the length of the material to be rolled after each rolling pass.

  Further, the process computer 70 recalculates the transport line based on the deceleration rate α. From this result, the target extraction time of the material to be rolled 1 from the heating furnace 10 is recalculated.

  Now, the story changes after the material to be rolled 1 is actually extracted from the heating furnace 10, but it is upstream of the material to be rolled that has been decided to reduce the speed. When the actual time at which the material to be rolled arrives at the main equipment on the side or the main equipment itself is later than the expected arrival time predicted before extraction from the heating furnace 10 If the speed reduction of a part of the rough rolling of the material to be rolled is reduced, the extra speed reduction can be reduced by that amount, and unnecessary reduction in rolling efficiency can be avoided.

  Specific examples are shown below. The material to be rolled 1 decided to be decelerated by the process computer 70 is extracted from the heating furnace 10. After that, when the material to be rolled 1 reaches a detection device (not shown) installed on the entry side of the rough rolling mill to be decelerated, the arrival of the material 1 to be rolled is transmitted to the process computer 70 as a signal. Here, the process computer 70 compares the estimated arrival time to the detection device calculated when the workpiece 1 is extracted from the heating furnace 10 with the actual arrival time, and calculates the difference Δt. If the actual result is delayed, that is, if Δt> 0, the process computer 70 sets the correction rate α ′ (1 <α ′ <1 / α) of the deceleration rate α obtained by calculation before extraction. The following equation (4) is used for calculation.

   α ′ = min (1, k3Δt / (αk2ΔT_F)) (4)

  Then, the process computer 70 obtains the speed V_ supplement of the rough rolling pass to be reduced by the following equation (5), and performs speed control by this.

    V_ supplement = V_ installation × α × α ′ (5)

  As described above, the actual temperature before extracting the material to be rolled from the heating furnace is compared with the target extraction temperature, and the actual temperature before extracting the material to be rolled from the heating furnace 10 is higher. In this case, a part of the speed of the rough rolling of the material to be rolled is decelerated, or further, the time when the material to be rolled starts a rough rolling pass to be decelerated is extracted from the heating furnace 10. When it becomes late compared to the estimated time of arrival predicted at the previous time point, by reducing the deceleration, the conveyance of the material to be rolled during rough rolling is scheduled at the time scheduled by the mill pacing control. On the other hand, while being able to be able to be done while avoiding as early as possible, delaying or disturbing as much as possible, it is possible to suppress the occurrence of quality defects associated with the temperature tolerance of each subsequent rolled material and the occurrence of poor quality. Temperature control can be performed.

  In addition, although the above Example demonstrated the case where the number of rough rolling mills was three, this invention is not limited to this, It is applicable even if the number of rough rolling mills is any number. Moreover, it is applicable not only to batch rolling but also to continuous hot rolling (endless rolling) performed in a hot rolling line such as the hot endless rolling line 200 shown in FIG. In FIG. 6, 11 is a coil box, 101 is a measuring roll, 141 is a cropping shear, 151 is a joining device, 17 is a seat bar heater, 171 is an edge heater, and 102 and 103 are thermometers provided before and after that. , 26 is a high-speed threading device, and 27 is a cutting device.

Diagram showing an example of a hot rolling line to which the present invention is applied Diagram for explaining the problems of the prior art Diagram for explaining the prior art Flow chart showing the basic procedure of the present invention The diagram for demonstrating the method of calculation of the temperature of the to-be-rolled material which concerns on embodiment of this invention The diagram which shows an example of another hot rolling line to which this invention is applied

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A, 1B ... Rolled material 2 ... Roll 9 ... Width press 10 ... Heating furnace 11 ... Coil box 101 ... Measuring roll 102, 103 ... Thermometer 12, R1, R2, R3 ... Rough rolling mill 14 ... Crop shear 141 ... Crop shear (for joining)
DESCRIPTION OF SYMBOLS 15 ... Finishing side thermometer 151 ... Joining device 16 ... Descaling device 17 ... Sheet bar heater 171 ... Edge heater 18, F1, F2, ... F7 ... Finishing rolling mill 21 ... Finishing side thermometer 23 ... Run-out table 24 ... Coiler 25 ... Coiler inlet side thermometer 26 ... High-speed plate device 27 ... Cutting device

Claims (3)

In hot rolling,
Compare the actual temperature before extracting the material to be rolled from the furnace and the target extraction temperature,
When the actual temperature before extracting the material to be rolled from the heating furnace is higher,
A temperature control method for a material to be rolled in hot rolling, characterized in that a part of the speed of rough rolling of the material to be rolled is reduced. For the material to be rolled that has been decided to reduce the speed,
The actual time at which the material to be rolled arrives at the main equipment on the upstream side of the deceleration, or at the main equipment itself, is predicted to be reached before extraction from the heating furnace. If it ’s slower,
The method for controlling the temperature of a material to be rolled in hot rolling according to claim 1, wherein a reduction in the speed of a part of the rough rolling of the material to be rolled is reduced.   A hot rolling method using the temperature control method according to claim 1 or 2.

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