JP4920458B2 - Temperature prediction method and rolling method for rolled material, temperature prediction system and rolling system for rolled material - Google Patents

Description

  The present invention predicts a temperature rising due to heat generation during cold rolling of a rolled material such as metal and adjusts rolling conditions, a rolling material temperature prediction method and a rolling method, a rolled material temperature prediction system, and It relates to a rolling system.

  When the material to be rolled is cold-rolled, the temperature rises due to heat generation and friction. Since the temperature of the material to be rolled affects the surface quality and the like of the product after cold rolling, it is required to be managed accurately.

  For example, in cold rolling of steel strips, slip sheets are used to prevent wrinkling. When the temperature of the steel strip after the end of cold rolling is high, the inserted slip paper reacts with the lubricating oil and the base of the steel strip, and the slip paper is seized on the steel strip surface. The part on which the interleaving paper is baked becomes a pattern that is whitened by the pickling process. Such a pattern is a surface defect particularly in a stainless steel strip that requires a beautiful surface among the steel strips, which causes a quality problem. Here, the phenomenon in which the slip sheet is baked on the steel strip is called paper burn-in.

  From experience, the temperature of the stainless steel strip after cold rolling is less than 90 ° C., or even if it is 90 ° C. or more, it is less than 90 ° C. after passing through a so-called empty pass plate without rolling. When it is cooled down, the occurrence of image sticking after annealing pickling can be prevented.

  Therefore, as a method for preventing the occurrence of paper seizure, a cooling step of passing an empty pass after rolling is included, and the temperature of the steel strip after rolling is set to be lower than the limit temperature for the occurrence of paper seizure. Conceivable. Among these, an empty pass plate that is simply used for cooling is not preferable because it increases the number of extra steps and deteriorates productivity. Therefore, by lowering the rolling speed, the cooling time of the steel strip by the lubricating oil is lengthened, and by reducing the speed of processing strain, the amount of heat generated by processing is reduced. A method is adopted in which the temperature during the inter-rolling is less than the limit temperature for occurrence of paper burn-in.

  However, if the temperature of the steel strip at the time of cold rolling cannot be obtained with high accuracy, there is a concern that productivity is deteriorated by slowing the rolling speed more than necessary because of concern about the occurrence of paper burn-in. When the steel strip is cold-rolled, the rolling speed is so fast that it reaches a level of several thousand meters per minute and reaches 1000 m. Therefore, reducing the rolling speed more than necessary as a measure for paper burn-in affects productivity. Therefore, in order to prevent the occurrence of paper burn-in and increase the rolling speed within a range where the occurrence of paper burn-in can be prevented, it is necessary to accurately obtain the temperature of the steel strip during cold rolling.

  As a method for measuring the temperature of the material to be rolled during cold rolling, it is conceivable to use a contact thermometer such as a thermocouple. However, since the contact-type thermometer measures the temperature while directly contacting the surface of the material to be rolled, contact wrinkles may be generated on the surface of the material to be rolled, and it is often impossible to use due to surface quality problems.

  It is also conceivable to use a non-contact type thermometer such as a radiation thermometer. The non-contact type thermometer does not touch the surface of the material to be rolled, so there is no problem in surface quality, but the emissivity changes depending on the material and surface state of the material to be rolled, and it occurs during cold rolling. Since fume and external light become disturbances, the accuracy of the measurement temperature may deteriorate.

  As one method for solving such a problem, it has been proposed that a temperature analysis model is assumed and the temperature of the material to be rolled is predicted by calculation (see, for example, Non-Patent Document 1). According to Non-Patent Document 1, the temperature of the material to be rolled at the time of cold rolling is (1) processing heat generated by rolling of the material to be rolled, (2) friction heat generated by friction between the material to be rolled and the rolling roll, (3) Cooling of the material to be rolled by the cooling medium, (4) Contact heat loss between the rolling roll and the material to be rolled, and (5) Sum of five elements of cooling by forced convection.

  In Non-Patent Document 1, the frictional heat generation among the five elements is calculated assuming that the friction coefficient between the material to be rolled and the rolling roll is constant. However, the coefficient of friction between the material to be rolled and the rolling roll during cold rolling varies in a short time depending on the surface roughness of the material to be rolled, the peripheral speed of the rolling roll, the temperature of the cooling medium, and the like. Since the fluctuating friction coefficient cannot be obtained in real time, the accuracy of the predicted temperature of the material to be rolled becomes worse if the frictional heat is calculated with the friction coefficient being constant.

Thus, since it is difficult to calculate the heat generation of the material to be rolled during cold rolling and obtain it with high accuracy, it has been proposed to obtain it from the output of the electric motor of the rolling mill based on empirical rules (see Patent Document 1). . In Patent Document 1, processing heat generation and frictional heat generation of a material to be rolled at the time of rolling are calculated from the output of a rolling mill motor called rolling power consumption. That is, the amount of heat input given to the rolling roll from the material to be rolled is obtained by multiplying the rolling power consumption by the heat input rate and a constant. When the amount of water for cooling the rolling roll is controlled according to the amount of heat input, the temperature of the rolling roll is controlled to be a desired temperature.
Japan Iron and Steel Institute Joint Study Group, Rolling Theory Division, “Theory and Practice of Sheet Rolling”, Japan Iron and Steel Institute, September 1, 1984, p156-160 JP 2002-66622 A

  However, Patent Document 1 does not disclose or suggest that the temperature of the material to be rolled is predicted based on the rolling power consumption, and the temperature rise on the material to be rolled side based on the predicted temperature of the material to be rolled. The idea of preventing the occurrence of surface defects due to the above is not disclosed at all.

  An object of the present invention is to accurately predict the temperature of a material to be rolled during cold rolling, to prevent the occurrence of surface defects, and to maintain a high productivity and a method for predicting the temperature of the material to be rolled and a rolling method And providing a temperature prediction system and a rolling system for the material to be rolled.

In order to solve the problem, the method of predicting the temperature of the material to be rolled according to the present invention performs the rolling process for each time when the material to be rolled is cold-rolled while cooling with a cooling medium before and after the rolling stand in each pass. In each pass, the temperature of the material to be rolled inserted into the rolling stand is defined as the inlet side temperature, the measured temperature in the first pass, and the outlet side material discharged from the rolling stand in the previous pass in the second pass. Set the delivery temperature to be predicted as the temperature of the rolled material, and the temperature of the material to be rolled immediately before rolling in each pass, and cooling by the cooling medium while the material to be rolled moves to just before the rolling roll The pre-mill temperature that decreases from the entry side temperature is predicted based on the entry side temperature and heat transfer from the material to be rolled to the cooling medium, and the post-processing temperature that is the temperature immediately after the material to be rolled is rolled. , Temperature before mill, rolling roll The output of the motor to be driven, the heat capacity of the material to be rolled per unit time, and predicted on the basis of the thermal equivalent of work, a temperature of the rolled material is discharged from the rolling stands, immediately after the rolling roll material to be rolled The outlet side temperature that decreases from the post-processing temperature due to cooling by the cooling medium while moving from is estimated based on the post-processing temperature and heat transfer from the material to be rolled to the cooling medium.

  The rolling method of the present invention is a rolling method in which the material to be rolled is cold-rolled while cooling with a cooling medium before and after the rolling stand in each pass over a plurality of passes. When the predicted exit temperature of the material to be rolled is equal to or higher than a predetermined limit temperature, the rolling speed is adjusted so that the exit temperature of the material to be rolled is less than the limit temperature and is as close to the limit temperature as possible. It is characterized by doing.

Further, the temperature prediction system for a material to be rolled according to the present invention is a method for predicting a temperature when a material to be rolled is cold-rolled while cooling with a cooling medium before and after the rolling stand in each pass over a plurality of passes. A temperature prediction system for measuring the temperature of the material to be rolled, and in the first pass, the temperature measured by the temperature measuring means is set as the entry side temperature of the material to be rolled to be loaded into the rolling stand. In the second and subsequent passes, an entry side temperature setting means for setting an exit side temperature, which is predicted as a temperature of the exit side material to be discharged from the rolling stand in the previous pass, as an entrance side temperature is rolled. The temperature of the material to be rolled immediately before the rolling, and the temperature before the mill that decreases from the temperature on the inlet side by cooling with the cooling medium while the material to be rolled moves to just before the rolling roll, Cooling medium A mill before temperature calculating means for calculating, based on the heat transfer to,
The post-processing temperature, which is the temperature immediately after the material to be rolled, is calculated based on the pre-mill temperature, the output of the electric motor that drives the rolling roll, the heat capacity of the material to be rolled per unit time, and the work heat equivalent. The post-processing temperature calculation means and the temperature of the material to be rolled discharged from the rolling stand, and the outlet side temperature lowered from the post-processing temperature by cooling with a cooling medium while the material to be rolled moves from immediately after the rolling roll. , A post-processing temperature, and a delivery temperature calculating means for calculating based on heat transfer from the material to be rolled to the cooling medium.

  Further, the rolling system of the present invention is a rolling system for cold rolling while cooling the material to be rolled over a plurality of passes and cooling with a cooling medium before and after the rolling stand in each pass. Comparing means for comparing the delivery side temperature predicted by the system and the temperature prediction system for the material to be rolled with a predetermined limit temperature, and the exit side temperature is equal to or higher than the predetermined limit temperature according to the comparison result of the comparison means. And a speed adjusting means for adjusting the rolling speed so that the outlet temperature is less than the limit temperature and is as close to the limit temperature as possible.

  According to the present invention, the post-processing temperature of the material to be rolled is predicted using the output of the electric motor that drives the rolling roll, and the pre-mill temperature and the output before and after the rolling are based on the heat transfer from the material to be rolled to the cooling medium. By predicting the side temperature, it is possible to accurately predict the temperature of the material to be rolled during cold rolling.

  In addition, since the prediction accuracy of the exit side temperature of the material to be rolled is high, the surface caused by the temperature rise of the material to be rolled by adjusting the rolling speed to ensure that the exit side temperature is less than the limit temperature according to the prediction result Generation of defects can be prevented. Furthermore, the productivity of rolling can be kept high by adjusting the rolling speed so as to be as close to the critical temperature as possible below the critical temperature, that is, by increasing the rolling speed to near the allowable limit.

  FIG. 1: shows the outline | summary of the temperature prediction method of the to-be-rolled material as one Embodiment of this invention. FIG. 2 shows a calculation formula used for the temperature prediction method of the material to be rolled. In addition, the coolant in description in a figure represents the cooling medium.

  The temperature prediction of the material 1 to be rolled, such as a stainless steel strip, is performed when the material to be rolled 1 is cold rolled while being cooled by the cooling medium 3 before and after the rolling stand 2 in a plurality of passes. The cooling medium 3 is a liquid material used for the purpose of suppressing the temperature rise of the material to be rolled 1 and lubrication of rolling, and includes an inlet wiper 4 provided on the inlet side of the rolling stand 2 and an outlet side provided on the outlet side. It is supplied to the surface of the material to be rolled between the wiper 5 and the rolling roll 2a from a constant temperature bath not shown through a pipe.

  The concept of temperature prediction of the present invention is also based on the elements included in the five elements (1) to (5) of the above-mentioned non-patent document. However, since the contact time with the rolling roll 2a provided in the rolling stand 2 is short when viewed from the material to be rolled 1, contact heat loss with the rolling roll 2a can be ignored. In addition, since forced cooling of the material 1 to be rolled by air blowing or the like is not performed, cooling by forced convection can be ignored. Therefore, in this invention, the temperature of the to-be-rolled material 1 is estimated based on the process heat generation and frictional heat generation of the to-be-rolled material 1 at the time of rolling, and the cooling by the cooling medium 3.

  First, for each pass, the temperature of the material to be rolled 1 charged into the rolling stand 2 is set as the entry side temperature T1. The entry side temperature T1 is set to an actually measured temperature in the first pass, and an exit side temperature predicted as the temperature of the exit side material 1 discharged from the rolling stand 2 in the previous pass in the second pass. The actual measurement of the entry side temperature T1 of the material to be rolled 1 in the first pass can be performed using either a contact thermometer or a non-contact thermometer. The contact-type thermometer measures the temperature by contacting the surface of the material 1 to be rolled. However, since the contact-type thermometer stops only at the local contact before the start of rolling, the yield reduction due to surface defects does not become a problem. Further, with respect to the non-contact type thermometer, there is no generation of fumes or the like before the start of rolling, so that it is not necessary to consider a decrease in measurement accuracy. Setting the outlet temperature predicted in the previous pass as the incoming temperature T1 in the second and subsequent passes will be described later.

  A pre-mill temperature T2 as the temperature of the material 1 to be rolled immediately before rolling in each pass is predicted based on the entry side temperature T1 and the heat transfer from the material 1 to the cooling medium 3. FIG. 3 schematically shows heat transfer from the material to be rolled 1 to the cooling medium 3. The pre-mill temperature T2 is a temperature that is reached from the entry side temperature T1 by the heat transfer to the cooling medium 3 while the material to be rolled 1 moves from the entry side wiper 4 to just before the rolling roll 2a. Can be obtained by equation (1).

T2 = Tw + (T1-Tw) exp (-2h _w1 × t _c1 / (ρ × Cs × h1))
... (1)
Where Tw: temperature of the cooling medium
h _w1 : heat transfer coefficient of the inlet side cooling medium
t _c1 : cooling time by the inlet side cooling medium
ρ: Density of material to be rolled
Cs: Specific heat of material to be rolled
h1: Entry side plate thickness of the material to be rolled.

In the formula (1), the temperature Tw of the cooling medium 3 can be actually measured, the density ρ and the specific heat Cs of the material 1 to be rolled are determined by the type of the material 1 to be rolled, The cooling time t _c1 by the inlet side cooling medium 3 is determined by the rolling conditions.

The heat transfer coefficient h _w1 of the inlet side cooling medium is unknown and needs to be obtained. Note that the heat transfer coefficient h _w1 of the entry side cooling medium is the difference (T1−Tw) between the entry side temperature T1 of the material to be rolled 1 and the temperature Tw of the cooling medium 3, and the cooling medium from the material to be rolled 1 per unit time. 3 is a value to be obtained based on the thermal energy transferred to 3 and the area where the material 1 to be rolled contacts the cooling medium 3. However, here, the heat transfer coefficient is assumed to be a value determined by the temperature of the material to be rolled 1 before being cooled by the cooling medium, the flow rate of the cooling medium, and the coefficient, and is determined based on an empirical rule. A method for _{obtaining this} will be described later together with the heat transfer coefficient _hw2 of the outlet side cooling medium.

  Next, FIG. 4 shows how to obtain heat generated by rolling the material 1 to be rolled. The output W of the mill motor 6, which is an electric motor that drives the rolling roll 2a, is consumed for processing the material to be rolled 1 and propelling the material to be rolled 1 in the rolling direction, and is converted into heat and vibration. The output W of the mill motor 6 may be referred to as mill power W. Since the rate at which the mill power W is converted into heat is considered to be determined according to the rolling conditions, the mill power can be calculated without individually calculating the sum of processing heat generated by rolling and frictional heat generation. It can be obtained from W. The post-processing temperature T3 is a temperature obtained by adding a temperature increase due to processing heat generation and friction heat generation to the pre-mill temperature T2. In the temperature prediction method, a post-processing temperature T3 that is a temperature immediately after the material to be rolled 1 is rolled, a pre-milling temperature T2, a mill power W, a heat capacity Hc of the material 1 to be rolled per unit time, and heat of work. Predict based on the equivalent ηp. The predicted value can be obtained by equation (2).

T3 = T2 + ηp × W / (ρ × b × v × h2 × Cs) (2)
Where ρ is the density of the material to be rolled
b: Plate width of the material to be rolled
v: Rolling speed
h2: Outboard thickness after rolling of the material to be rolled
Cs: Specific heat of the material to be rolled.

  Note that (ρ × b × v × h2 × Cs) is obtained by multiplying the volume of the material 1 to be rolled per unit time by the density and the specific heat, and can be represented by a heat capacity Hc.

  In the formula (2), the mill power W can be actually measured, the density ρ and the specific heat Cs of the material 1 to be rolled are determined by the type of the material 1 to be rolled, and the exit side plate thickness h2 and the plate width b of the material 1 to be rolled. The rolling speed v is determined by the rolling conditions. The work heat equivalent ηp can be determined as follows. Experiments for actually measuring the pre-mill temperature T2 and the post-processing temperature T3 under various rolling conditions are repeated, and the work heat equivalent ηp is obtained as a value based on an empirical rule so that the actually measured temperature and the predicted temperature are in good agreement.

  A delivery temperature T4 as the temperature of the material 1 to be rolled discharged from the rolling stand 2 is predicted based on the post-processing temperature T3 and the heat transfer from the material 1 to the cooling medium 3. The delivery side temperature T4 is a temperature reached by being cooled from the post-processing temperature T3 by heat transfer to the cooling medium 3 while the material to be rolled 1 moves from the rolling roll 2a to the delivery side wiper 5, and its predicted value is It can be obtained by equation (3).

T4 = Tw + (T3−Tw) exp (−2h _w2 × t _c2 / (ρ × Cs × h2))
... (3)
Where Tw: temperature of the cooling medium
h _w2 : heat transfer coefficient of the outlet side cooling medium
t _c2 : Cooling time by the outlet side cooling medium
ρ: Density of material to be rolled
Cs: Specific heat of material to be rolled
h2: Outboard thickness after rolling of the material to be rolled.

In Formula (3), except for the heat transfer coefficient h _w2 of the outlet side cooling medium, it is determined by actual measurement in the same manner as in Formula (1), and by the type of rolling material 1 and rolling conditions. Since the heat transfer coefficient h _w2 of the outlet side cooling medium is unknown, it needs to be obtained. A method for obtaining the heat transfer coefficient h _w2 of the outlet side cooling medium together with the heat transfer coefficient h _w1 of the previous inlet side cooling medium will be described.

FIG. 5 shows the assumptions for determining the heat transfer coefficient of the cooling medium. Here, it is assumed that the heat transfer coefficient of the cooling medium is a value determined by the temperature of the material to be rolled 1 before being cooled by the cooling medium, the flow rate of the cooling medium, and the coefficient. In other words, the heat transfer coefficient h _w1 of the inlet side cooling medium is expressed by Expression (4), and the heat transfer coefficient h _w2 of the outlet side cooling medium is expressed by Expression (5).

h _w1 = α × T1 ^β × F ^γ
... (4)
h _w2 = α × T3 ^β × F ^γ
... (5)
Where α, β, γ: coefficients
T1: Inlet temperature
T3: Temperature after processing
F: The flow rate of the cooling medium.

Formula (5) includes post-processing temperature T3. The post-milling temperature T3 includes a pre-milling temperature T2 as can be seen from equation (2). Furthermore, the pre-mill temperature T2 includes the inlet side temperature T1 and the heat transfer coefficient h _w1 of the inlet side cooling medium as can be seen from the equation (1). Since the inlet side temperature T1 can be actually measured at least in the first pass, the prediction accuracy of the pre-mill temperature T2 in the first pass depends on the heat transfer coefficient h _w1 of the inlet side cooling medium. Furthermore, the prediction accuracy of the post-machining temperature T3 depends on the pre-mill temperature T2. The prediction accuracy of the outlet side temperature T4 depends on the post-processing temperature T3 and the heat transfer coefficient _hw2 of the outlet side cooling medium. From this, the prediction accuracy of the outlet side temperature T4 depends on the heat transfer coefficients h _w1 and h _w2 of both the inlet side and outlet side cooling media.

The heat transfer characteristics of the cooling medium are determined by its physical properties. Since the same cooling medium is used for the inlet side and the outlet side, the coefficients α, β, and γ in the heat transfer coefficients h _w1 , h _w2 of the inlet side and outlet side cooling mediums expressed by the equations (4) and (5) are set. It can be assumed that the entry side and the exit side are the same. Based on this assumption, the coefficients α, β, and γ are set based on empirical rules by determining the coefficients α, β, and γ so that the outgoing temperature T4 obtained from the prediction formula matches or is as close as possible to the measured outgoing temperature. The heat transfer coefficient h _w1 of the side cooling medium and the heat transfer coefficient h _w2 of the outlet side cooling medium can be obtained.

The method for determining the coefficients α, β, and γ is not particularly limited, but can be obtained as follows, for example. First, among the three coefficients, β and γ are fixed to fixed fixed values, and only α is changed to various values to calculate the outlet temperature T4 from the prediction formula (3). Find the correlation with temperature. The value of α when the highest correlation is obtained is defined as the coefficient α. Next, α is fixed to a value determined from the correlation, γ is fixed to the previously determined constant value, only β is changed to various values, and the outlet temperature T4 is calculated from the prediction formula (3). A correlation is obtained for the calculation result and the measured delivery side temperature. The value of β when the highest correlation is obtained is defined as the coefficient β. Finally, α and β are fixed to values determined from the correlation, the coefficient γ is changed to various values, and the coefficient γ is determined in the same manner as for α and β. Substituting the coefficients α, β and γ obtained by this operation into the equations (4) and (5) to obtain the heat transfer coefficient h _w1 of the inlet side cooling medium and the heat transfer coefficient h _w2 of the outlet side cooling medium. it can. By using the heat transfer coefficients h _w1 and h _w2 of the cooling medium thus obtained, the temperature of the material to be rolled 1 can be predicted.

  The temperature prediction method of the present invention is used when the material to be rolled 1 is cold-rolled over a plurality of passes as described above. Therefore, temperature prediction is performed for both reverse rolling in which the material to be rolled 1 is rolled in the opposite direction for each pass, and tandem rolling in which the material to be rolled 1 is rolled in one direction on a plurality of rolling stands provided in parallel. The method can be applied.

  In the case of cold rolling over a plurality of passes, in the second and subsequent passes, the delivery temperature T4 predicted as the temperature of the delivery material 1 to be discharged from the rolling stand in the previous pass is replaced with the entry temperature T1. Then, prediction calculation of the pre-mill temperature T2, the post-processing temperature T3, and the outlet side temperature T4 is performed.

  That is, when reverse rolling is completed and rolling in the next pass is performed in the opposite direction, the outgoing temperature T4 predicted in the previous pass is replaced with the incoming temperature T1 in the equation (1). The above-described prediction calculation is performed by reversing the setting conditions on the side and the output side. In tandem rolling, when rolling is completed at one rolling stand and rolling of the next pass is performed at an adjacent rolling stand, the outgoing temperature T4 predicted in the previous pass is replaced with the incoming temperature T1 in equation (1). At the same time, the above-described prediction calculation is performed using the setting conditions of the adjacent rolling stand where the workpiece 1 is next charged.

  In the case of using a stainless steel strip as the material 1 to be rolled, cold rolling is performed while cooling with the cooling medium 3 before and after the rolling stand 2 in each pass over a plurality of passes in a reverse cold rolling mill, and a temperature prediction method FIG. 6 shows the result of obtaining the correlation between the calculated outgoing temperature T4 and the measured outgoing temperature.

  According to the relational expression obtained by the correlation, the temperature difference between the calculated outgoing side temperature T4 and the actually measured outgoing side temperature is within ± 4 ° C. As described above, according to the temperature prediction method, it is possible to accurately predict the temperature of the stainless steel strip during cold rolling even when the prediction calculation of the outlet side temperature is repeatedly performed according to a plurality of passes. is there.

  Next, the rolling method of the present invention using the temperature prediction method will be described. The rolling method of the present invention is predicted by the above-described temperature prediction method in a rolling method in which the material to be rolled 1 is cold-rolled while being cooled by the cooling medium 3 before and after the rolling stand 2 in a plurality of passes. When the delivery temperature T4 of the material 1 to be rolled is equal to or higher than a predetermined limit temperature, the rolling speed is adjusted so that the delivery temperature T4 of the material 1 is less than the limit temperature and is as close to the limit temperature as possible. It is characterized by doing.

  Here, a rolling method is specifically illustrated about the case where a stainless steel strip is cold-rolled as the material 1 to be rolled. When the material 1 to be rolled is a stainless steel strip, a temperature that can prevent the occurrence of paper image sticking, which is a surface defect, is set as the limit temperature. Since the seizure resistance varies depending on the type of interleaving paper, a limit temperature that can prevent the occurrence of paper image seizure cannot be uniquely determined, but the limit temperature is often about 90 ° C. in many cases.

When the outlet side temperature T4 of the stainless steel strip is equal to or higher than the limit temperature, the rolling speed is adjusted so that the outlet side temperature T4 is less than the limit temperature and as close to the limit temperature as possible. Of cold rolling, it is performed only in the final pass.
This is due to the following reason. The paper burn-in of the stainless steel strip occurs when the stainless steel strip is wound for a long time above the limit temperature after the final pass rolling. Therefore, even if a condition where the delivery temperature T4 becomes equal to or higher than the limit temperature appears in the middle pass of rolling, if rolling is performed under conditions such that the delivery temperature T4 becomes less than the limit temperature in the final pass of rolling, the stainless steel Since the steel strip is wound up and kept below the limit temperature, the occurrence of paper burn-in is prevented.

  According to the rolling method of the present invention, since the prediction accuracy of the outlet side temperature T4 of the stainless steel strip is high, the rolling speed is adjusted to ensure that the outlet side temperature T4 of the final pass is less than the limit temperature according to the prediction result. Thus, the occurrence of paper burn-in caused by the temperature rise of the stainless steel strip can be prevented. Furthermore, the productivity of cold rolling of stainless steel strip is kept high by adjusting the rolling speed so that it is as close to the critical temperature as possible below the critical temperature, that is, by increasing the rolling speed to near the allowable limit. be able to.

  Further, in the middle path among a plurality of paths, the outlet temperature T4 is allowed to be higher than the limit temperature, but it is not preferable to raise the temperature excessively in consideration of characteristics such as mechanical properties. Therefore, even in the middle pass rolling, it is required to accurately control the delivery temperature for quality control. According to the present invention, since the delivery temperature can be predicted with high accuracy, the delivery temperature of the stainless steel strip in the intermediate path can also be managed with high accuracy. As a result, the rolling speed can be increased within a temperature range that is permitted under high-precision temperature control even in the midway pass, so that it is possible to maintain high rolling productivity.

  FIG. 7 shows a schematic configuration of a rolling system including a temperature prediction system for a material to be rolled according to the present invention. FIG. 7 illustrates a system configuration based on the reverse cold rolling mill 9. Since the reverse type cold rolling mill 9 has a configuration similar to that of the rolling mill shown in FIG. 1 described above, the same parts are denoted by the same reference numerals and description thereof is omitted. In the reverse rolling mill 9, the material 1 to be rolled is unwound from the rewind reel 7, rolled by the rolling stand 2, and wound by the take-up reel 8. During cold rolling, the take-up reel 8 acts as a tension reel that applies rolling tension to the material 1 to be rolled. Since it is a reverse type, in the next pass, the rewind reel 7 and the take-up reel 8 roll the material 1 to be rolled with its action reversed.

  First, the temperature prediction system 11 of the material to be rolled provided in the rolling system 10 will be described. In addition, the temperature prediction system 11 of a material to be rolled is simply abbreviated as a temperature prediction system 11. The temperature prediction system 11 is a system suitable for using the above-described temperature prediction method. The material to be rolled 1 is cooled while being cooled by the cooling medium 3 before and after the rolling stand 2 in each pass over a plurality of passes. The temperature of the material 1 to be rolled when rolling is predicted.

  The temperature prediction system 11 includes a temperature measurement device 12, an entrance side temperature setting device 13, a pre-mill temperature computation device 14, a post-processing temperature computation device 15, and an exit side temperature computation device 16. In the present embodiment, the entry side temperature setting device 13, the pre-mill temperature calculation device 14, the post-processing temperature calculation device 15, and the exit side temperature calculation device 16 are integrated to form the calculation device 20. The arithmetic device 20 is realized by a personal computer, for example.

  The temperature prediction system 11 further includes a controller 17, an analog / digital conversion device 18, and an input device 19 in addition to the components described above. The analog-digital conversion device 18 is abbreviated as A / D device 18.

  The temperature measuring device 12 is a radiation thermometer which is a kind of non-contact type thermometer. The radiation thermometer 12 is used to measure the entry side temperature T1 of the material to be rolled 1 inserted into the rolling stand 2 in the first pass. The measurement result of the inlet side temperature T1 is given to the inlet side temperature setting device 13 of the arithmetic unit 20 via the A / D device 18.

  The controller 17 receives the mill power W output from the mill motor 6 and the rolling speed v detected from the rotational speed of the mill motor 6, and the temperature of the cooling medium, which is a rolling condition determined as a production plan. Tw, the flow rate F of the cooling medium, the sheet width b of the material to be rolled, the inlet side plate thickness h1 and the outlet side plate thickness h2 for each pass, the number of rolling passes for each material to be rolled, and the like are input in advance. These mill power W, rolling conditions, and the like are also given from the controller 17 to the arithmetic unit 20 via the A / D device 18.

  The controller 17 outputs a rolling completion signal and a pass switching signal to the arithmetic device 20 via the A / D device 18 in accordance with the number of passes for each rolled material input in advance. The rolling completion signal is a signal output when rolling of the final pass is completed among the predetermined number of passes for each material to be rolled, and the pass switching signal is when the rolling of passes other than the final pass is completed. This is an output signal. According to the output signal from the controller 17, the arithmetic unit 20 sets the path after receiving the rolling completion signal as the first path, and when receiving the path switching signal, sets the path as the second or later path and switches the path. Each time a signal is received, one pass is added to the number of passes and the number of passes is set.

The input device 19 connected to the arithmetic device 20 is realized by a keyboard or the like, for example. As constants used for temperature prediction of the material 1 to be rolled, the specific heat Cs of the material to be rolled, the density ρ of the material to be rolled, the inlet side cooling medium cooling distance L _c1 , the outlet side cooling medium cooling distance Lc2, the work heat equivalent ηp, Coefficients α, β, and γ for obtaining the heat transfer coefficient of the cooling medium are input from the input device 19 to the arithmetic device 20.

In addition, the rolling speed v, the inlet side plate thickness h1 and the outlet side plate thickness h2 are input to the arithmetic unit 20 from the controller 17, and the inlet side cooling medium cooling distance L _c1 and the outlet side cooling medium cooling distance L _c2 are input from the input device 19. Since it is input, the cooling time t _c1 and t _c2 by the inlet side and outlet side cooling medium used for temperature prediction are calculated in the arithmetic unit 20.

  The entry side temperature setting device 13 receives the rolling completion signal or the path switching signal output from the controller 17, and sets the entry side temperature T <b> 1 of the material 1 to be rolled inserted into the rolling stand 2. In the case of the first pass after receiving the rolling completion signal, the temperature measured by the radiation thermometer 12 is set as the entry side temperature T1, and in the second and subsequent passes receiving the pass switching signal, the previous pass The delivery side temperature T4 predicted as the temperature of the delivery side material 1 discharged from the rolling stand 2 is set as the entry side temperature T1. The incoming temperature T1 is output to the pre-mill temperature calculation device 14.

  The pre-mill temperature calculation device 14 uses a pre-mill temperature T2 as a temperature of the material 1 to be rolled immediately before being rolled, an entry side temperature T1 given from the entry side temperature setting device 13, and a cooling medium from the material 1 to be rolled. 3 is calculated based on the heat transfer to 3. This calculation is performed according to the above-described equation (1). Numerical values necessary for calculation other than the input side temperature T1 are given from the controller 17 via the A / D device 18 and also from the input device 19. The pre-mill temperature T2 as the calculation result is output to the post-processing temperature calculation device 15.

The post-processing temperature calculation device 15 sets the post-processing temperature T3, which is the temperature immediately after the material to be rolled 1 is rolled, to the pre-mill temperature T2, the mill power W, and the unit time given from the pre-mill temperature calculation device 14. Calculation is based on the heat capacity Hc of the material to be rolled and the heat equivalent of work ηp. This calculation is performed according to the above-described equation (2). Numerical values necessary for calculation other than the pre-mill temperature T2 are given from the controller 17 via the A / D device 18 and from the input device 19. The post-processing temperature T3 as the calculation result is output to the outlet temperature calculation device 16.
The delivery side temperature calculation device 16 cools the delivery side temperature T4 as the temperature of the material to be rolled 1 discharged from the rolling stand 2 and the post-processing temperature T3 given from the post-processing temperature computation device 15 and the material to be rolled 1. Calculation is performed based on heat transfer to the medium 3. This calculation is performed according to the above-described equation (3). Numerical values necessary for the calculation other than the post-processing temperature T3 are given from the controller 17 via the A / D device 18 and from the input device 19.

  When the input side temperature setting device 13 receives the path switching signal output from the controller 17, the input side temperature setting device 13 sets the output side temperature T4, which is a prediction result calculated by the output side temperature calculating device 16 as the input side temperature T1. The arithmetic unit 20 replaces the predicted outlet temperature T4 with the inlet temperature T1, and calculates the pre-mill temperature T2, the post-machining temperature T3, and the outlet temperature T4. In this way, by repeatedly calculating by replacing the outlet side temperature T4 with the inlet side temperature T1, the outlet side temperature T4 when rolling over a plurality of passes can be predicted for each pass.

  Since the temperature of the workpiece 1 predicted by the temperature prediction system 11 is predicted according to the above-described temperature prediction method, the prediction accuracy is high, and the temperature prediction system 11 has the same effect as that obtained by the temperature prediction method. Can play.

  Next, the rolling system 10 provided with the temperature prediction system 11 is demonstrated. As shown in FIG. 7, a rolling system 10 based on a reverse cold rolling mill 9 is illustrated. The rolling system 10 includes a reverse cold rolling mill 9, the temperature prediction system 11 described above, a comparison device 21, and a speed adjustment device 22.

  The comparison device 21 in the rolling system 10 of the present embodiment is configured to be integrated with the arithmetic device 20 of the temperature prediction system 11, and is realized by, for example, a substrate of a personal computer. The comparison device 21 compares the outlet temperature T4 predicted by the temperature prediction system 11 with a predetermined limit temperature. The comparison between the delivery side temperature T4 and the limit temperature is performed by calculating the difference between the limit temperature input in advance from the input device 19 and the delivery side temperature T4 calculated by the delivery side temperature calculation device 16. When the difference between the limit temperature and the exit side temperature T4 is positive, the comparison device 21 compares the comparison result that the exit side temperature T4 is less than the limit temperature, and when the difference is 0 or negative, the output side A comparison result that the temperature T4 is equal to or higher than the limit temperature is output to the speed adjusting device 22.

  The speed adjusting device 22 includes a display device 23 and an operation panel 24. When the outlet side temperature T4 is equal to or higher than the limit temperature according to the comparison result of the comparison device 21, the outlet side temperature T4 is less than the limit temperature. The rolling speed is adjusted so that the temperature is as close to the limit temperature as possible.

  The display device 23 includes a display unit made up of a liquid crystal display, a cathode ray tube, and the like. indicate. Further, it is preferable that the rolling speed v given from the controller 17 to the computing device 20 is also displayed on the display device 23.

  The comparison result by the comparison device 21 is displayed on the display device 23 as follows, for example. When the delivery temperature T4 is equal to or higher than the limit temperature, an instruction to slow the rolling speed by turning on the red warning lamp is displayed. On the other hand, when the delivery side temperature T4 is lower than the limit temperature, it is displayed that the temperature is appropriate.

  The operation panel 24 is a device for controlling the rolling operation of the reverse rolling mill 9. The operator 25 operates the operation panel 24 to adjust the rolling speed in accordance with the comparison result by the comparison device 21 displayed on the display device 23 and the calculation result by the outlet side temperature calculation device 16. That is, when the red warning light is turned on, the rolling speed is adjusted to be slow so that the delivery temperature T4 is less than the limit temperature and as close to the limit temperature as possible based on the display of the calculation result by the delivery temperature calculation device 16. I do. Even when there is an indication of the appropriate temperature, if the exit side temperature T4 is considerably lower than the limit temperature and the rolling speed is too slow, the exit side temperature T4 is less than the limit temperature and the limit temperature is set as much as possible. Make adjustments to increase the rolling speed so that they are close.

  In this way, it is possible to prevent the delivery temperature T4 of the material 1 to be rolled from exceeding the limit temperature, so that when the stainless steel strip is cold-rolled as the material 1 to be rolled, the occurrence of paper burn-in is prevented. It becomes possible. In addition, the rolling speed can be adjusted to be as close as possible to the limit temperature without exceeding the limit temperature. Therefore, the rolling speed is increased within the range in which the occurrence of paper seizure can be prevented to maintain high rolling productivity. be able to.

(Example)
Examples of the present invention will be described below. In this example, a stainless steel strip of a steel type SUS304 defined in Japanese Industrial Standard G4305 was used as a material to be rolled, and cold rolling was performed over a plurality of passes in a rolling system 10 including a temperature prediction system 11 shown in FIG. .

Example 1
In Example 1, a stainless steel strip having a plate thickness of 1.30 mm and a plate width of 1034 mm was cold-rolled to a plate thickness of 0.585 mm in 6 passes, and the output temperature T4 was calculated by the temperature prediction system, and the rolling stand The result of measuring the temperature of the stainless steel strip on the delivery side was compared. The actual temperature of the outlet side of the stainless steel strip was measured with a contact-type thermometer at the center in the length direction of the stainless steel strip and used as a representative value for each pass. Although the contact-type thermometer may cause surface flaws on the stainless steel strip, it was measured with a contact-type thermometer with emphasis on measurement accuracy for verification accuracy prediction. Table 1 shows the numerical values used for temperature prediction other than the rolling conditions and the values detected and used during rolling.

  FIG. 8 shows a comparison result between the calculated outlet temperature T4 and the actually measured temperature. In FIG. 8, a line 31 represented in a staircase pattern is the actually measured temperature, and a line 32 represented as a trapezoid is connected to the temperature T4 calculated by the temperature prediction method. Since the calculation of the temperature prediction was repeatedly performed at intervals of 1 second even during the rolling of one pass, the calculated output side temperature T4 is obtained as a value that slightly fluctuates even during one pass according to the detected value of the mill power W or the like. It is done.

  When the maximum value of the calculated outgoing temperature T4 is compared with the actually measured temperature, both pass well with each other except for the fourth pass. In the fourth pass, the difference between the maximum value of the calculated delivery temperature T4 and the actually measured temperature is several degrees Celsius. From this, it can be seen that the prediction accuracy by the temperature prediction method is high.

(Example 2)
In Example 2, the stainless steel strip was cold-rolled over a plurality of passes to a finish thickness of around 0.60 mm, and the rolling speed of the example and the rolling speed of the comparative example were compared.

  In the final pass of the embodiment, the rolling speed is adjusted to be as close to the limit temperature as possible below the limit temperature in accordance with the comparison result by the comparison device 21 displayed on the display device 23 and the calculation result by the outlet temperature calculation device 16. And rolled. Further, in the intermediate path other than the final path of the embodiment, even if the temperature exceeds the limit temperature, it is allowed. Therefore, while confirming the calculation result by the output temperature calculation device 16 displayed on the display device 23, the mechanical properties, etc. Rolling was carried out by adjusting the rolling speed as fast as possible within a temperature range where there was no problem in characteristics.

  On the other hand, in the comparative example, without using a temperature prediction system at all, according to the measurement result by the radiation thermometer, so that it does not exceed the limit temperature in the final pass, and within the temperature range where there is no problem in characteristics in the intermediate pass. Rolling was performed by adjusting the rolling speed. However, in the case of the comparative example according to the measurement result of the radiation thermometer, quality control is performed for both the limit temperature in the final pass and the predetermined temperature in the intermediate pass, taking into account that the accuracy of the temperature measurement value decreases due to fumes etc. The rolling speed was adjusted with the aim of slightly lower than the predetermined value in anticipation of a safe temperature range.

  FIG. 9 shows the result of comparing the rolling speed for the midway pass and the final pass. FIG. 9 also shows the rolling speeds obtained when each of the stainless steel strips having 4 coils in the example and 11 coils in the comparative example was cold-rolled. In FIG. 9, the diamond marks and the numbers shown in the vicinity thereof represent the average value of the rolling speed. Compared with the comparative example, in the example, the rolling speed was improved by 10% or more on average in both the final pass and the intermediate pass.

  By performing cold rolling while adjusting the rolling speed according to the highly accurate temperature prediction result, the rolling speed of the final pass can be made less than the limit temperature, and the rolling speed of the intermediate pass can be made as fast as possible within the predetermined temperature range. As a result, the production tonnage per hour in one reverse rolling mill could be improved by about 8% from 15.2 tons to 16.4 tons.

  In addition, as a result of continuous cold rolling of stainless steel strips using a rolling system equipped with a temperature prediction system, the temperature of the stainless steel strip after cold rolling can be controlled with high accuracy in predicting the exit temperature of the final pass. Since it became possible to carry out strictly, the amount of paper burn-in of the stainless steel strip was reduced to several coils per month, and the quality yield could be improved.

It is a figure which shows the outline | summary of the temperature prediction method of the to-be-rolled material as one Embodiment of this invention. It is a figure which shows the calculation formula used for the temperature prediction method of FIG. It is a figure which shows typically the heat transfer from the to-be-rolled material 1 of FIG. 1 to the cooling medium 3. FIG. It is a figure which shows how to obtain | require the heat | fever which generate | occur | produces when the to-be-rolled material 1 of FIG. 1 is rolled. It is a figure which shows the assumption about calculating | requiring the heat transfer coefficient of the cooling medium of FIG. It is a graph which shows an example of the correlation with the calculation output side temperature T4 by the temperature prediction method of FIG. 1, and actual measurement output side temperature. It is a block diagram which shows schematic structure of a rolling system provided with the temperature prediction system of the to-be-rolled material of this invention of FIG. It is a graph which shows the comparison result of the delivery side temperature T4 by calculation of FIG. 1, and measured temperature. It is a graph which shows the result of having compared the rolling speed about the intermediate | middle pass and final pass of the rolling system of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rolled material 2 Rolling stand 3 Cooling medium 6 Mill motor 9 Reverse type cold rolling mill 10 Rolling system 11 Temperature prediction system 12 Radiation thermometer 13 Inlet side temperature setting device 14 Pre-mill temperature calculation device 15 Post-processing temperature calculation device 16 Outlet temperature calculation device 17 Controller 20 Calculation device 22 Speed adjustment device

Claims (4)

When cold-rolling the material to be rolled over multiple passes and cooling with a cooling medium before and after the rolling stand in each pass, the temperature of the material to be rolled inserted into the rolling stand is entered for each pass. As the temperature, in the first pass, the measured temperature is set, and in the second and subsequent passes, the outgoing side temperature is predicted as the temperature of the outgoing side material to be discharged from the rolling stand in the previous pass,
The temperature of the material to be rolled immediately before being rolled in each pass, and the temperature before the mill that falls from the entry side temperature by cooling with a cooling medium while the material to be rolled moves to just before the rolling roll , Predict based on temperature and heat transfer from the work piece to the cooling medium,
Predicts the post-processing temperature, which is the temperature immediately after the material to be rolled, based on the pre-mill temperature, the output of the electric motor that drives the rolling roll, the heat capacity of the material to be rolled per unit time, and the work heat equivalent And
It is the temperature of the material to be rolled discharged from the rolling stand, and the exit side temperature that decreases from the post-processing temperature by cooling with a cooling medium while the material to be rolled moves from immediately after the rolling roll, A method for predicting a temperature of a material to be rolled, which is predicted based on heat transfer from the rolled material to a cooling medium. In a rolling method in which the material to be rolled is cold-rolled while cooling with a cooling medium before and after the rolling stand in each pass over a plurality of passes,
When the outlet temperature of the material to be rolled predicted by the method for predicting the temperature of the material to be rolled according to claim 1 is equal to or higher than a predetermined limit temperature,
A rolling method characterized by adjusting a rolling speed so that a delivery temperature of a material to be rolled is less than a limit temperature and is as close to a limit temperature as possible. A temperature prediction system for a material to be rolled, which predicts the temperature when cold rolling while performing cooling with a cooling medium before and after a rolling stand in each pass over a plurality of passes,
Temperature measuring means for measuring the temperature of the material to be rolled;
In the first pass, the temperature measured by the temperature measuring means is set as the entry side temperature of the material to be rolled into the rolling stand. In the second and subsequent passes, the discharge discharged from the rolling stand in the previous pass is performed. Entry side temperature setting means for setting the exit side temperature to be predicted as the temperature of the material to be rolled on the side as the entrance side temperature;
The temperature of the material to be rolled immediately before being rolled , and the temperature before the mill that decreases from the entry side temperature by cooling with a cooling medium while the material to be rolled moves to just before the rolling roll, Pre-mill temperature calculation means for calculating based on heat transfer from the rolled material to the cooling medium;
The post-processing temperature, which is the temperature immediately after the material to be rolled, is calculated based on the pre-mill temperature, the output of the electric motor that drives the rolling roll, the heat capacity of the material to be rolled per unit time, and the work heat equivalent. Post-processing temperature calculation means,
It is the temperature of the material to be rolled discharged from the rolling stand, and the exit side temperature that decreases from the post-processing temperature by cooling with a cooling medium while the material to be rolled moves from immediately after the rolling roll, A temperature predicting system for the material to be rolled, comprising: a temperature calculating means for calculating a temperature based on heat transfer from the rolled material to the cooling medium. In the rolling system for cold rolling the material to be rolled over multiple passes, cooling with a cooling medium before and after the rolling stand in each pass,
The temperature prediction system for the material to be rolled according to claim 3,
Comparison means for comparing the outlet side temperature predicted by the temperature prediction system of the material to be rolled with a predetermined limit temperature;
According to the comparison result of the comparison means, when the delivery side temperature is equal to or higher than a predetermined limit temperature, the speed adjustment means for adjusting the rolling speed so that the delivery side temperature is less than the limit temperature and is as close to the limit temperature as possible. And a rolling system comprising:

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