EP0453566A1 - Steel material cooling control method - Google Patents
Steel material cooling control method Download PDFInfo
- Publication number
- EP0453566A1 EP0453566A1 EP89907279A EP89907279A EP0453566A1 EP 0453566 A1 EP0453566 A1 EP 0453566A1 EP 89907279 A EP89907279 A EP 89907279A EP 89907279 A EP89907279 A EP 89907279A EP 0453566 A1 EP0453566 A1 EP 0453566A1
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- European Patent Office
- Prior art keywords
- cooling
- steel
- transformation
- temperature
- control method
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
- B21B37/76—Cooling control on the run-out table
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D11/00—Process control or regulation for heat treatments
- C21D11/005—Process control or regulation for heat treatments for cooling
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
- C21D9/54—Furnaces for treating strips or wire
- C21D9/56—Continuous furnaces for strip or wire
- C21D9/573—Continuous furnaces for strip or wire with cooling
Definitions
- the present invention relates to a control method of cooling a steel, and more specifically to that suitable for use in accurately controlling a hot rolled steel to a predeterfmined target temperature.
- a hot rolling system forms in general a steel coil by winding a steel sheet being a hot drawn steel after rolling the sheet, with a coiler. To wind up such a steel sheet, the steel sheet should be cooled to a temperature suitable for the winding. In the hot rolling system, the steel sheet is cooled by a cooling system R illustrated in Fig. 5, for example.
- the hot rolling system is constructed such that a finishing rolling machine 1 rolls the steel sheet S, which sheet is then forcedly sent on a run-out table (not shown) in the direction of a arrow A in the figure and wound up by a coiler 6.
- a cooling system R along the run-out table which is to cool the steel sheet S to a temperature suitable for the winding.
- the cooling system R includes on the side of an inlet thereof an inlet thermometer 2 for measuring the termperature of the steel sheet S to be cooled, and on the side of an outlet thereof an outlet thermometer 5 for measuring the temperature of the steel sheet S after cooled.
- the cooling system R is separated into two and disposed across vertically the run-out table. Each the separated portion includes a water cooling section 3 for cooling the steel sheet S by pouring water thereon and an air cooling section 4 for cooling the same with air.
- the air cooling section 4 has the same structure as the water cooling section 3 when the latter stops the pouring of water on the steel sheet S.
- the water cooling section 3 and the air cooling section 4 disposed on the upper and lower sides of the cooling system R are divided into N cooling banks as designated at numerals 1 through N in the figure, respectively. Each bank is controllable in its cooling capability to cool the steel sheet S.
- the cooling system R is divided into a plurality of cooling zones each including the cooling banks of one or more along the run-out table, the cooling capability of each cooling zone being controlled by controlling the amount of supply of a cooling medium (cooling water) from each bank to the steel sheet S in conformity with the travelling of the steel sheet S.
- a cooling medium cooling water
- the rate W of the transformation of a steel material indicative of the temporal development of the transformation of the same under cooling changes by a curve as illustrated in Fig. 6 (B), and the amount Q T of the heat production changes in proportion to the gradient ( ⁇ W / ⁇ T) of the rate W with respect to time T.
- the rate W of the transformation changes as illustrated to the same figure (B)
- the gradient ( ⁇ W / ⁇ T) of the rate W changes as illustrated in the same figure (C).
- the actual amount Q T of the heat production in the transformation changes as illustrated in the same figure (D).
- the conventional technique just-mentioned above to control the cooling ignores the temporal development of the transformation of a steel but supposing the amount Q T of the heat production in the transformation being as illustrated in the same figure (A), without taking the actual amount Q T of the heat production in the transformation which changes as illustrated in the same fignure (D), for example, at the initiation and completion of the transformation. So, estimation accuracy depends on accuracy of pre-measured data, and a measuring error directly causes error in cooling control. Then, it has a drawback of the accuracy of temperature estimation being lowered followed by the cooling control with insufficient accuracy.
- a control method of cooling a steel according to the present invention for controlling the temperature of the steel at a predetermined position on a line or at a predetermined time to a desired target temperature comprising: estimating the temperature of the steel taking into consideration the temporal development of transformation of the steel, and determining the amount of cooling on the basis of the estimated temperature of the steel.
- the estimation of the steel temperature is performed by correcting steel temperature estimated on the basis of the time of cooling the steel and on the cooling capability of a cooling system in response to the temporal development of the transformation of the steel caused by the cooling.
- the temporal development of the transformation of the steel is considered for a change in the amount of the heat production upon the transformation of the steel depending on the change in the rate of the transformation of the steel.
- the rate of the transformation is detected by using a transformation rate sensor.
- the rate of the transformation is established by learning an output of a transformation rate sensor.
- the cooling capability of the cooling system is established by learning the results of the cooling, the speed of carrying the steel and the detected temperature.
- the cooling control is conducted by changing the amount of cooling water of each cooling bank and/or number of working banks according to the amount of cooling.
- the cooling control is conducted by combining a water cooling and an air cooling according to the combination of temperature curves which are based on inlet temperature and outlet temperature, respectively, the number of water poured banks are changed at the cooling zone where both cooling curves intersect with each other, and cooling is conducted according to a cooling curve which combines both cooling curves.
- the temperature of the steel to be cooled is estimated taking the temporal development of the transformation of the steel under cooling into consideration, and the amount of cooling is controlled based upon the estimated temperature.
- any erroneous estimation of the steel temperature with respect to an actual steel temperature in cooling can greatly be reduced, assuring accurate control of the amount of cooling followed by the realization of cooling which provides a desired change of the temperature. This establishes the manufacture of a steel of stable quality with high productively.
- the temporal development of the transformation of the steel when the temporal development of the transformation of the steel is considered for a change in the amount of heat produced upon the transformation of the steel depending on the change in the rate of the transformation of the steel, the temporal development of the transformation to be expressed in terms of an objective numerical value, say the amount of heat production of the steel by the transformation thereby facilitating the estimation of the steel temperature.
- the first embodiment is a control apparatus wherein the control method of the present invention is executed to cool a hot drawn steel with use of a cooling system R in a cooling apparatus located on a hot drawing line as illustrated in Fig. 1.
- the cooling system R is of the same construction as that shown in Fig. 5, wherein the steel sheet S rolled through the finishing rolling machine 1 is successiveively wound up by the coiler 6 through the cooling system R.
- the finishing rolling machine 1 disposed on the inlet side of the cooling system R includes an inlet speed detector 10 for detecting the carrying speed of the steel sheet S carried after rolled by the finishing rolling machine 1.
- the coiler 6 disposed on the outlet side of the cooling system R includes an outlet speed detector 12 for detecting the wind-up speed of the steel sheet S.
- the cooling system R which includes a predetermined number of cooling zones, each zone having at least one cooling bank.
- the puring amount of coolant (for example, water) from the cooling bank is controlled to control the cooling of the steel sheet S passing through each cooling zone.
- the inlet thermometer 2, inlet speed detector 10 and outlet speed detector 12 shown in Fig. 1 transmit respective detection signals to a cooling bank output pattern determining unit 14.
- the cooling bank output pattern determining unit 14 determines by computation a pattern to control the cooling capability of each cooling bank according to a cooling time t (hereinafter, referred to as a cooling bank pattern) for obtaining the desired temperature decrease of the steel sheet S in response to the cooling time t based upon the inputted inlet side temperature, the carrying speed of the steel sheet S, the wind-up speed, a preset target termperature of the steel sheet S and sheet thickness, etc..
- the cooling bank pattern determined as described above is inputted into a cooling bank switching input/output unit 16.
- the cooling bank switching input/output unit 16 controls the cooling capability of each cooling bank in response to the inputted cooling bank pattern.
- Cooling results of pouring water by each bank of the cooling system R controlled by the bank switching input/output unit 16 are fed into a learning control unit 18.
- the learning control unit 18 receives detection signals from the inlet speed detector 10, the output speed detector 12, the inlet thermometer 2, and the outlet thermometer 5, and learns the cooling capability of the cooling system R on the basis of the inputted aforesaid cooling results and the detection signals.
- the change in the temperature of the steel sheet S after the lapse of predetermind time is estimated on the basis of the cooling time of the steel sheet S and of the cooling capability of the cooling system R.
- the amount of heat production of the steel sheet S for example, due to the transformat ion of the same is calculated in the response to the temporal development of the transformation caused by the cooling of the steel sheet S.
- the error of the estimated change in the temperature of the steel sheet S is corrected by the calculated amount of heat production of the steel sheet S due to the transformation of the same.
- the cooling bank pattern of the cooling system R is determined for cooling control so as to provide the corrected amount of the change in the temperature of the steel sheet S.
- A, B, and C are parameters determined by the component, temperature, thickness, and cooling pattern of each steel sheet S. More specifically, A is a parameter for calculating the rate of the transformation, B and C are coefficients for learning. The accuracy of estimating the rate W of the transformation can be increased by correcting the coefficients for learning according to the learning results based on signals from a plurality of sensors for detecting the transformation rate, disposed in the cooling system.
- the transformation rate sensor comprises by a combination of an exiting coil and magnetic detecting element, for example, and the transformation rate is detected by measuring phase transformation through a change in magnetic permeability.
- the means to know the temporal development of the transformation of the steel sheet S is not limited to the one which utilizes the relatioship of the equation (1).
- the transformation rate sensor to directly detect the rate of the transformation can bae used.
- H latent heat of the steel sheet S upon the transformation (a physical quantity which can be determined from the component of the steel sheet S, the kind of the same, and the temperature of the same).
- the amount of heat production Q T upon the transformation in each cooling zone when the steel sheet S is cooled from the inlet temperature FDT to the target temperature CT is calculated by using the equation (2). Then the termperature change of the steel sheet S estimated from the cooling time of the steel sheet S and the capability of the cooling system R is corrected by the amount of heat production Q Ti upon the transformation so calculated. In consequence, the accurate temperature change of the steel sheet S as the sheet passes through each cooling zone can be estimated.
- the number of the water pouring banks in each cooling zone is determind with use of the following temperature model equation (3) which shows the temperature change ⁇ Tiw in water cooling in the ith cooling zone and the following temperature model equation (4) which shows the temperature change ⁇ Tia in air cooling in the ith cooling zone.
- Cp is the specific heat
- ⁇ the specific gravity
- ⁇ ui the coefficient of cooling capacity of each upper cooling bank
- ⁇ di the coefficient of cooling capacity of each lower cooling bank
- TI the temperature of the steel sheet S at the inlet of the ith cooling zone
- Tw the temperature of the cooling water
- Cj the emission constant
- ⁇ ROLL the heat transfer coefficient (for the associated roll)
- Tair air temperature
- Fig. 2 illustrates the cooling bank pattern.
- the cooling bank pattern is a target of the temperature change to be realized for the steel sheet S in each cooling bank when the steel sheet S is cooled by the cooling system R from the inlet temperature FDT to the target temperature CT.
- a symbol A denotes a temperature change curve by air cooling (hereinafter, referred to as an air cooling curve A)
- a symbol B denotes a temperature change curve by water cooling (hereinafter, referred to as a water cooling curve B).
- the cooling system R shares the cooling between the cooling zones to a predetermined one located in the vicinity of the inlet for the water cooling and those located in the vicinity of the outlet for the air cooling. For this, the water cooling curve B passes through the inlet temperature FDT, while the air cooling curve A passing through the target temperature CT.
- the water cooling curve B is obtained by calculating the temperature change ⁇ Tiw using the equation (3) when water pouring valves are opened in succession from the first cooling bank to actuate the respective cooling zones to the ith cooling zone.
- the calculated temperature change ⁇ Tiw is corrected by the amount of the heat production Q Ti due to the transformation calculated by the equation (2).
- the air cooling curve A is obtainable by correcting the temperature change ⁇ Ta calculated using the equation (4) by the aforementioned amount of the heat production Q Ti due to the transformation.
- a hatched portion designated at a symbol Q T in the figure corresponds to the temperature rise of the steel sheet S which might be caused by the amount of the heat production Q T in the transformation, for correction the cooling curves A, B.
- a cooling curve designated at C in the figure (hereinafter, referred to as a water cooling curve C) is required for changing smoothly the temperature of the steel sheet S from Tm to Tm+1.
- the cooling capacity of the cooling banks in the aforementioned mth cooling zone is adjusted. The adjustment of the cooling capacity is done by changing the number of the water pouring cooling banks in the zone.
- the various parameters are first inputted into the cooling bank output pattern determining unit 14 in Step 105.
- the parameters include the target temperature CT, the cooling pattern of each bank, the inlet temperature FDT, the inlet speed, the outlet speed, and the thickness of the steel sheet S, etc. Then, the amount of heat production Q Ti of the steel sheet S under cooling is calculated by the equation (2) in Step 110.
- Step 120 the temperature change ⁇ Ti by the air cooling by each cooling bank is calculated by the equation (4) for determining the cooling curve A which passes through the target temperature CT.
- Step 130 the temperature change ⁇ Tiw by the water cooling by each cooling bank is calculated for determining the water cooling curve B.
- the calculation is done in succession starting from the 1st cooling zone until the water cooling curve B resulting from the present calculation becomes less than the air cooling curve A calculated in Step 120.
- the details are as follows.
- Step 131 cooling zones, for which the temperature changes ⁇ Tiw have been calculated, are set in succession.
- Step 132 the total of the temperature changes ⁇ Tiw up to the finally set cooling bank is calculated.
- Step 133 it is judged whether or not a value of the total temperature change substracted from the inlet side temperature FDT, i.e., the water cooling curve B is smaller than the air cooling curve A.
- Step 133 if the result in Step 133 is positive, i.e., if the value of the cooling curve B is judged to be smaller than the value of the cooling curve A, then the operation advances to Step 140.
- a cooling zone which first gives the positive result, is assumed to be a mth one.
- values giving the water cooling curve B are evaluated in succession up to the just-mentioned mth cooling zone.
- Step 140 in order to achieve the cooling control in the mth cooling zone such that the steel sheet S is changed in its temperature following the water cooling curve C, the number of the water pouring banks, is determined by calculation, The number of the water pouring banks is determined such that the temperature Tm of the steel sheet S on the entrance side of the present cooling zone becomes a temperature Tm+1 of the air cooling curve A on the exit side of the same.
- the completion of the calculation in this Step 140 gives the cooling bank output pattern.
- the cooling bank output pattern such as illustrated in Fig. 2 as determined by the cooling bank output pattern determining unit 14 as described above is inputted into a cooling bank switching input/output unit 16.
- the cooling bank switching input/output unit 16 controls the pouring of water in each cooling bank according to the inputted cooling bank output pattern while inputting results of the pouring in each cooling bank into the learning control unit 18.
- the learning control section 18 learns the inputted pouring results, the inlet speed of the steel sheet S, the output speed of the same, and the inlet and outlet temperature, etc., and supplies to the bank output pattern determining unit 14 data for determination of the optimum cooling bank output pattern for the sucessive cooling control based upon the learned values.
- a plurality of transformation rate sensor 20 are disposed in the cooling system R.
- Learning coefficient for calculating the actual rate of the transformation is calculated in a transformation rate calculating unit 22 based on output signal from the respective transformation rate sensors 20 and inputted into the learning control unit 18 as is the first embodiment. Then, the learning coefficient used in the equation (1) is corrected.
- the optimum cooling control of the steel sheet S is thus assured by taking the temporal development of the transformation into consideration using the heat production of the steel sheet S caused by the transformation of the same.
- a cooling bank output pattern as illustrated in Fig. 2, i.e., a cooling pattern for water cooling from the inlet side of the cooling apparatus was described.
- Another cooling bank output pattern is possible according to the present invention without limitation to the cooling where the illustrated cooling bank output pattern is persued. That is, such modifications are achievable in response to cooling condition.
- a cooling bank output pattern where the first half of the cooling system R performs the air cooling while the second half of the same performing the water cooling, can be obtained by constructing the cooling bank output pattern such that the water cooling curve B reaches the target temperature CT and the air cooling curve A reaches the inlet temperature FDT.
- the present invention may be applied for lines and steels without limitation thereto.
- the present invention can be applied to steels such as thick steel, line steel, rod steel when they are cooled after hot processing.
- the present invention is most suitable in particular for use, in a cooling zone of a cooling system for cooling a hot drawn steel, in cooling the steel to a temperature of suited to the winding of the steel.
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Abstract
Description
- The present invention relates to a control method of cooling a steel, and more specifically to that suitable for use in accurately controlling a hot rolled steel to a predeterfmined target temperature.
- A hot rolling system forms in general a steel coil by winding a steel sheet being a hot drawn steel after rolling the sheet, with a coiler. To wind up such a steel sheet, the steel sheet should be cooled to a temperature suitable for the winding. In the hot rolling system, the steel sheet is cooled by a cooling system R illustrated in Fig. 5, for example.
- As illustrated in the figure, the hot rolling system is constructed such that a finishing rolling
machine 1 rolls the steel sheet S, which sheet is then forcedly sent on a run-out table (not shown) in the direction of a arrow A in the figure and wound up by acoiler 6. There is disposed a cooling system R along the run-out table which is to cool the steel sheet S to a temperature suitable for the winding. The cooling system R includes on the side of an inlet thereof aninlet thermometer 2 for measuring the termperature of the steel sheet S to be cooled, and on the side of an outlet thereof anoutlet thermometer 5 for measuring the temperature of the steel sheet S after cooled. - The cooling system R is separated into two and disposed across vertically the run-out table. Each the separated portion includes a
water cooling section 3 for cooling the steel sheet S by pouring water thereon and anair cooling section 4 for cooling the same with air. Theair cooling section 4 has the same structure as thewater cooling section 3 when the latter stops the pouring of water on the steel sheet S. Thewater cooling section 3 and theair cooling section 4 disposed on the upper and lower sides of the cooling system R are divided into N cooling banks as designated atnumerals 1 through N in the figure, respectively. Each bank is controllable in its cooling capability to cool the steel sheet S. - To control the cooling of the steel sheet S by the cooling system R, the cooling system R is divided into a plurality of cooling zones each including the cooling banks of one or more along the run-out table, the cooling capability of each cooling zone being controlled by controlling the amount of supply of a cooling medium (cooling water) from each bank to the steel sheet S in conformity with the travelling of the steel sheet S.
- It is essential upon controlling the cooling capability of the cooling system R as described above to estimate the amount of the cooling for the steel sheet S, i.e., the amount of a change in the temperature of the same, in each cooling zone. For this, there have hitherto been proposed varieties of techniques to estimate the temperature of the steel sheet S under cooling and execute the cooling control with high accuracy. A technique is known among those techniques described above, as disclosed in Japanese Laid-Open Publication No. 61-199580, wherein learning on heat transfor coefficients and heat emission rates through and from the upper and lower surfaces of the steel sheet S in running is determined by means of a Karman filter.
- However, steel materials produce some heat in general in their transformation from γ to α iron, for example form austenite to martensite. So, by the just-mentioned technique where in cooling capability of a cooling system is learned to estimate the temperature of the steel sheet for controlling the cooling, a problem causes that it is prevented from controlling the termperature of the steel sheet in due consideration of the heat production caused by the transformation of the steel, resulting in the reduced accurary of the cooling control.
- On the contrary, to consider the heat production caused by the transformation of a steel material, technique for controlling the cooling in consideration of transformation start timing and transformation time is disclosed in Reference on "Temperature Control in Winding of Hot Drawn High-Carbon Steel" presented at the Sectional Meeting on the 41th Hot Strip held at 1987. Japanese Patent Laid-Open Publication Nos. 57-7312, 58-199613 and 58-125312, etc.
- In this technique a temperature development of the transformation of a steel material is ignored and the amount of heat production in the transformation remains unchanged without depending on the lapse of time from the initiation of the transformation, and that the total amount of the heat production in the transformation varies in proportion to the lapse of time from the initiation of the transformation. In other words, it is considered in this technique that the amount QT of the heat production in the transformation changes stepwise from the transfomation initiation as shown in Fig. 6 (A).
- However, it should actually be considered that the rate W of the transformation of a steel material indicative of the temporal development of the transformation of the same under cooling changes by a curve as illustrated in Fig. 6 (B), and the amount QT of the heat production changes in proportion to the gradient ( ∂W / ∂T) of the rate W with respect to time T. For example, when the rate W of the transformation changes as illustrated to the same figure (B), the gradient (∂W / ∂T) of the rate W changes as illustrated in the same figure (C). Hereby, the actual amount QT of the heat production in the transformation changes as illustrated in the same figure (D).
- In contrast thereto, the conventional technique just-mentioned above to control the cooling ignores the temporal development of the transformation of a steel but supposing the amount QT of the heat production in the transformation being as illustrated in the same figure (A), without taking the actual amount QT of the heat production in the transformation which changes as illustrated in the same fignure (D), for example, at the initiation and completion of the transformation. So, estimation accuracy depends on accuracy of pre-measured data, and a measuring error directly causes error in cooling control. Then, it has a drawback of the accuracy of temperature estimation being lowered followed by the cooling control with insufficient accuracy.
- In view of the drawbacks of the conventional techniques, it is an object of the present invention to provide a control method of cooling a steel capable of accurate cooling control without causing erroneous estimation of steel temperature by determining the amount of cooling on the basis of steel temperature estimated taking the temporal development of the steel transformation upon cooling into consideration.
- To achieve the above object, a control method of cooling a steel according to the present invention for controlling the temperature of the steel at a predetermined position on a line or at a predetermined time to a desired target temperature comprising: estimating the temperature of the steel taking into consideration the temporal development of transformation of the steel, and determining the amount of cooling on the basis of the estimated temperature of the steel.
- Furthermore, in accordance with an embodiment of the present invention, the estimation of the steel temperature is performed by correcting steel temperature estimated on the basis of the time of cooling the steel and on the cooling capability of a cooling system in response to the temporal development of the transformation of the steel caused by the cooling.
- Furthermore, in accordance with an embodiment of the present invention, the temporal development of the transformation of the steel is considered for a change in the amount of the heat production upon the transformation of the steel depending on the change in the rate of the transformation of the steel.
- Furthermore, in accordance with an embodiment of the present invention, the rate W of the transformation is evaluated by the following formula as a function of the cooling time t:
where A, B, and C are parameters defined by the component, temperature, thickness, and geometrical cooling pattern of each steel used. - Furthermore, in accordance with an embodiment of the present invention, the rate of the transformation is detected by using a transformation rate sensor.
- Furthermore, in accordance with an embodiment of the present invention, the rate of the transformation is established by learning an output of a transformation rate sensor.
- Furthermore, in accordance with an embodiment of the present invention, the cooling capability of the cooling system is established by learning the results of the cooling, the speed of carrying the steel and the detected temperature.
- Furthermore, in accordance with an embodiment of the present invention, the cooling control is conducted by changing the amount of cooling water of each cooling bank and/or number of working banks according to the amount of cooling.
- Furthermore, in accordance with an embodiment of the present invention, the cooling control is conducted by combining a water cooling and an air cooling according to the combination of temperature curves which are based on inlet temperature and outlet temperature, respectively, the number of water poured banks are changed at the cooling zone where both cooling curves intersect with each other, and cooling is conducted according to a cooling curve which combines both cooling curves.
- In accordance with the control method of cooling a steel of the present invention, the temperature of the steel to be cooled is estimated taking the temporal development of the transformation of the steel under cooling into consideration, and the amount of cooling is controlled based upon the estimated temperature. Hereby, any erroneous estimation of the steel temperature with respect to an actual steel temperature in cooling can greatly be reduced, assuring accurate control of the amount of cooling followed by the realization of cooling which provides a desired change of the temperature. This establishes the manufacture of a steel of stable quality with high productively.
- Additionally, when the temporal development of the transformation of the steel is considered for a change in the amount of heat produced upon the transformation of the steel depending on the change in the rate of the transformation of the steel, the temporal development of the transformation to be expressed in terms of an objective numerical value, say the amount of heat production of the steel by the transformation thereby facilitating the estimation of the steel temperature.
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- Fig. 1 is a block diagram partly including a cross sectional view, illustrating the whole arrangement of a cooling apparatus associataed with a first embodiment of the present invention;
- Fig. 2 is a diagram illustrating an example of a cooling bank output pattern executed in a cooling system associated with the first embodiment;
- Fig. 3 is a flow chart illustrating an example of a procedure of determining the cooling bank output pattern;
- Fig. 4 is a block diagram partly including a cross sectional view, illustrating the whole arrangement of a second embodiment of the present invention;
- Fig. 5 is a cross sectional view illustrating an example of a conventional cooling apparatus; and
- Fig. 6 is diagrams illustrating an example of a relationship among the conventionally considered amount of heat production caused by transformation, the conventionally considered rate of the transformation, the actual amount of heat production caused by transformation, and the actual change in the rate of the transformation.
- In what follows, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
- The first embodiment is a control apparatus wherein the control method of the present invention is executed to cool a hot drawn steel with use of a cooling system R in a cooling apparatus located on a hot drawing line as illustrated in Fig. 1. The cooling system R is of the same construction as that shown in Fig. 5, wherein the steel sheet S rolled through the finishing rolling
machine 1 is succesively wound up by thecoiler 6 through the cooling system R. The finishing rollingmachine 1 disposed on the inlet side of the cooling system R includes aninlet speed detector 10 for detecting the carrying speed of the steel sheet S carried after rolled by the finishing rollingmachine 1. In addtion, thecoiler 6 disposed on the outlet side of the cooling system R includes anoutlet speed detector 12 for detecting the wind-up speed of the steel sheet S. There are further provided inlet andoutlet thermometers - Here, the like symbols shall be applied to the like configurations and operations us those in the conventional cooling system illustrated in Fig. 5, and detailed description is omitted.
- The cooling system R, which includes a predetermined number of cooling zones, each zone having at least one cooling bank. The puring amount of coolant (for example, water) from the cooling bank is controlled to control the cooling of the steel sheet S passing through each cooling zone.
- Here, the
inlet thermometer 2,inlet speed detector 10 andoutlet speed detector 12 shown in Fig. 1 transmit respective detection signals to a cooling bank outputpattern determining unit 14. The cooling bank outputpattern determining unit 14 determines by computation a pattern to control the cooling capability of each cooling bank according to a cooling time t (hereinafter, referred to as a cooling bank pattern) for obtaining the desired temperature decrease of the steel sheet S in response to the cooling time t based upon the inputted inlet side temperature, the carrying speed of the steel sheet S, the wind-up speed, a preset target termperature of the steel sheet S and sheet thickness, etc.. The cooling bank pattern determined as described above is inputted into a cooling bank switching input/output unit 16. The cooling bank switching input/output unit 16 controls the cooling capability of each cooling bank in response to the inputted cooling bank pattern. - Cooling results of pouring water by each bank of the cooling system R controlled by the bank switching input/
output unit 16 are fed into alearning control unit 18. Thelearning control unit 18 receives detection signals from theinlet speed detector 10, theoutput speed detector 12, theinlet thermometer 2, and theoutlet thermometer 5, and learns the cooling capability of the cooling system R on the basis of the inputted aforesaid cooling results and the detection signals. - In succession, operation of the first embodiment will be described.
- In the first embodiment, the change in the temperature of the steel sheet S after the lapse of predetermind time is estimated on the basis of the cooling time of the steel sheet S and of the cooling capability of the cooling system R. At the same time, the amount of heat production of the steel sheet S, for example, due to the transformat ion of the same is calculated in the response to the temporal development of the transformation caused by the cooling of the steel sheet S. Then, the error of the estimated change in the temperature of the steel sheet S is corrected by the calculated amount of heat production of the steel sheet S due to the transformation of the same. Then the cooling bank pattern of the cooling system R is determined for cooling control so as to provide the corrected amount of the change in the temperature of the steel sheet S.
- It will first be described how the temporal development of the transformation of the steel sheet S is obtained.
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- Here, A, B, and C are parameters determined by the component, temperature, thickness, and cooling pattern of each steel sheet S. More specifically, A is a parameter for calculating the rate of the transformation, B and C are coefficients for learning. The accuracy of estimating the rate W of the transformation can be increased by correcting the coefficients for learning according to the learning results based on signals from a plurality of sensors for detecting the transformation rate, disposed in the cooling system.
- The transformation rate sensor comprises by a combination of an exiting coil and magnetic detecting element, for example, and the transformation rate is detected by measuring phase transformation through a change in magnetic permeability.
- It is possible to know the temporal development of the transformation of the steel sheet S with respect to time by the equation (1). In addition, the means to know the temporal development of the transformation of the steel sheet S is not limited to the one which utilizes the relatioship of the equation (1). Instead, the transformation rate sensor to directly detect the rate of the transformation can bae used.
- On the assumption that in the cooling system R including the cooling zones of the predetermined number, the cooling time from the inlet side to the ith cooling zone is ti, the amount of the change in the rate of the transformation ΔWi (= Wi - Wi-1) in the ith cooling zone can be calculated on the basis of the cooling time ti (= ti - ti-1) in the ith cooling zone and the equation (1).
-
- Here, H is latent heat of the steel sheet S upon the transformation (a physical quantity which can be determined from the component of the steel sheet S, the kind of the same, and the temperature of the same).
- Therefore, the amount of heat production QT upon the transformation in each cooling zone when the steel sheet S is cooled from the inlet temperature FDT to the target temperature CT is calculated by using the equation (2). Then the termperature change of the steel sheet S estimated from the cooling time of the steel sheet S and the capability of the cooling system R is corrected by the amount of heat production QTi upon the transformation so calculated. In consequence, the accurate temperature change of the steel sheet S as the sheet passes through each cooling zone can be estimated.
- To realize the termperature change so estimated in each cooling zone, the number of the water pouring banks in each cooling zone is determind with use of the following temperature model equation (3) which shows the temperature change ΔTiw in water cooling in the ith cooling zone and the following temperature model equation (4) which shows the temperature change ΔTia in air cooling in the ith cooling zone. By using the above relations, cooling can be controlled so as to give desired temperature change to the steel sheet S considering the amount of heat production QT upon the transformation, namely the temporal development of the transformation.
- Here, Cp is the specific heat, ρ the specific gravity, α ui the coefficient of cooling capacity of each upper cooling bank, α di the coefficient of cooling capacity of each lower cooling bank, TI the temperature of the steel sheet S at the inlet of the ith cooling zone, Tw the temperature of the cooling water, Cj the emission constant, α ROLL the heat transfer coefficient (for the associated roll), and Tair is air temperature.
- Here, Fig. 2 illustrates the cooling bank pattern. The cooling bank pattern is a target of the temperature change to be realized for the steel sheet S in each cooling bank when the steel sheet S is cooled by the cooling system R from the inlet temperature FDT to the target temperature CT. In the figure, a symbol A denotes a temperature change curve by air cooling (hereinafter, referred to as an air cooling curve A), and a symbol B denotes a temperature change curve by water cooling (hereinafter, referred to as a water cooling curve B). In the first embodiment, the cooling system R shares the cooling between the cooling zones to a predetermined one located in the vicinity of the inlet for the water cooling and those located in the vicinity of the outlet for the air cooling. For this, the water cooling curve B passes through the inlet temperature FDT, while the air cooling curve A passing through the target temperature CT.
- The water cooling curve B is obtained by calculating the temperature change ΔTiw using the equation (3) when water pouring valves are opened in succession from the first cooling bank to actuate the respective cooling zones to the ith cooling zone. In this situation, to take the amount of the heat production QTi due to the transformation into consideration, the calculated temperature change ΔTiw is corrected by the amount of the heat production QTi due to the transformation calculated by the equation (2). In the same manner, the air cooling curve A is obtainable by correcting the temperature change ΔTa calculated using the equation (4) by the aforementioned amount of the heat production QTi due to the transformation. Here, a hatched portion designated at a symbol QT in the figure corresponds to the temperature rise of the steel sheet S which might be caused by the amount of the heat production QT in the transformation, for correction the cooling curves A, B.
- It should be noted here that in a cooling zone at an intersection between the water and air cooling curves B and A (hereinafter, the zone is assumed to be a mth one), a cooling curve designated at C in the figure (hereinafter, referred to as a water cooling curve C) is required for changing smoothly the temperature of the steel sheet S from Tm to Tm+1. For this, the cooling capacity of the cooling banks in the aforementioned mth cooling zone is adjusted. The adjustment of the cooling capacity is done by changing the number of the water pouring cooling banks in the zone.
- In succession, a procedure of determining the cooling bank pattern illustrated in Fig. 2, which is to be done in the cooling bank output
pattern determining unit 14, will be described with reference to a flow chart shown in Fig. 3. - After starting the apparatus, the various parameters are first inputted into the cooling bank output
pattern determining unit 14 inStep 105. The parameters include the target temperature CT, the cooling pattern of each bank, the inlet temperature FDT, the inlet speed, the outlet speed, and the thickness of the steel sheet S, etc. Then, the amount of heat production QTi of the steel sheet S under cooling is calculated by the equation (2) inStep 110. - In
Step 120, the temperature change ΔTi by the air cooling by each cooling bank is calculated by the equation (4) for determining the cooling curve A which passes through the target temperature CT. - In
Step 130, the temperature change ΔTiw by the water cooling by each cooling bank is calculated for determining the water cooling curve B. The calculation is done in succession starting from the 1st cooling zone until the water cooling curve B resulting from the present calculation becomes less than the air cooling curve A calculated inStep 120. The details are as follows. - That is, in
Step 131 cooling zones, for which the temperature changes ΔTiw have been calculated, are set in succession. InStep 132 the total of the temperature changes ΔTiw up to the finally set cooling bank is calculated. And inStep 133, it is judged whether or not a value of the total temperature change substracted from the inlet side temperature FDT, i.e., the water cooling curve B is smaller than the air cooling curve A. If the result is negative, i.e., the value of the water cooling curve B is larger than the value of the air cooling curve A, then the operation advances to Step 134 to increment by 1 the number of the associated cooling zone (i = i + 1), and returns to Step 132 for calculating the total of the temperature changes ΔTiw of the cooling zones up to the incremented number by 1, i.e., of the (i + 1)th cooling zone to calculate the value of the water cooling curve B in the cooling zone for the judgement inStep 133. - On the contrary, if the result in
Step 133 is positive, i.e., if the value of the cooling curve B is judged to be smaller than the value of the cooling curve A, then the operation advances to Step 140. Here, a cooling zone, which first gives the positive result, is assumed to be a mth one. Thus, values giving the water cooling curve B are evaluated in succession up to the just-mentioned mth cooling zone. - In the
above Step 140, in order to achieve the cooling control in the mth cooling zone such that the steel sheet S is changed in its temperature following the water cooling curve C, the number of the water pouring banks, is determined by calculation, The number of the water pouring banks is determined such that the temperature Tm of the steel sheet S on the entrance side of the present cooling zone becomes a temperature Tm+1 of the air cooling curve A on the exit side of the same. The completion of the calculation in thisStep 140 gives the cooling bank output pattern. - The cooling bank output pattern such as illustrated in Fig. 2 as determined by the cooling bank output
pattern determining unit 14 as described above is inputted into a cooling bank switching input/output unit 16. The cooling bank switching input/output unit 16 controls the pouring of water in each cooling bank according to the inputted cooling bank output pattern while inputting results of the pouring in each cooling bank into thelearning control unit 18. - The
learning control section 18 learns the inputted pouring results, the inlet speed of the steel sheet S, the output speed of the same, and the inlet and outlet temperature, etc., and supplies to the bank outputpattern determining unit 14 data for determination of the optimum cooling bank output pattern for the sucessive cooling control based upon the learned values. - As in the second embodiment shown in Fig. 4, a plurality of
transformation rate sensor 20 are disposed in the cooling system R. Learning coefficient for calculating the actual rate of the transformation is calculated in a transformationrate calculating unit 22 based on output signal from the respectivetransformation rate sensors 20 and inputted into thelearning control unit 18 as is the first embodiment. Then, the learning coefficient used in the equation (1) is corrected. -
- Wi
- is a transformation rate at sonsor i
- ti
- is a cooling time until sensor j
- B', C'
- are learning coefficients calculated from actual values.
-
- By using the learning coefficients B, C and the equation (1), the temporal development of transformation can be corrected by learning.
- The optimum cooling control of the steel sheet S is thus assured by taking the temporal development of the transformation into consideration using the heat production of the steel sheet S caused by the transformation of the same.
- Here, although in the above embodiments such a cooling bank output pattern as illustrated in Fig. 2, i.e., a cooling pattern for water cooling from the inlet side of the cooling apparatus was described. Another cooling bank output pattern is possible according to the present invention without limitation to the cooling where the illustrated cooling bank output pattern is persued. That is, such modifications are achievable in response to cooling condition. For example, a cooling bank output pattern, where the first half of the cooling system R performs the air cooling while the second half of the same performing the water cooling, can be obtained by constructing the cooling bank output pattern such that the water cooling curve B reaches the target temperature CT and the air cooling curve A reaches the inlet temperature FDT. In addition, other arbitrary cooling patterns can be obtained in the cooling control by each cooling zone by continuously controlling the poured water from each bank and the degree of the air cooling by each bank without limitation to the above-described procedure where any cooling pattern was determined by the pouring the water from each cooling bank and by the interruption of the pouring.
- Furthermore, although in the above embodiments the cooling apparatus for a steel sheet transferred on the hot rolling line was described as illustrated examples, the present invention may be applied for lines and steels without limitation thereto. For example, the present invention can be applied to steels such as thick steel, line steel, rod steel when they are cooled after hot processing.
- The present invention is most suitable in particular for use, in a cooling zone of a cooling system for cooling a hot drawn steel, in cooling the steel to a temperature of suited to the winding of the steel.
Claims (9)
- A control method of cooling a steel (S) for controlling the temperature of the steel at a predetermined position on a line or at a predetermined time to a desired target temperature characterized in that the method comprise the steps of:
estimating the temperature of the steel taking into consideration the temporal development of transformation of the steel, and
determining the amount of cooling on the basis of the estimated temperature of the steel. - A control method of cooling a steel according to claim 1 characterized in that said estimation of the steel temperature is performed by correcting steel temperature estimated on the basis of the time of cooling the steel and on the cooling capability of a cooling system in response to the temporal development of the transformation of the steel caused by the cooling.
- A control method of cooling a steel according to claim 1 characterized in that said temporal development of the transformation of the steel is considered for a change in the amount of heat (QTi) produced upon the transformation of the steel depending on the change in the rate W of the transformation of the steel.
- A control method of cooling a steel according to claim 3 characterized in that said rate W of the transformation is evaluated by the following formula as a function of the cooling time t:
where A, B, and C are parameters defined by the component, temperature, thickness, and geometrical cooling pattern of each steel used. - A control method of cooling a steel according to claim 3 characterized in that said rate W of the transformation is detected by using a transformation rate sensor (20).
- A control method of cooling a steel according to claim 3 characterized in that said rate W of the transformation is established by learning an output of a transformation rate sensor (20).
- A control method of cooling a steel sheet according to claim 2 charaterized in that said cooling capability of the cooling system is established by learning the results of the cooling, the speed of carrying the steel and the detected temperature.
- A control method of cooling a steel according to claim 1 characterized in that said cooling control is conducted by changing the amount of cooling water of each cooling bank and/or number of working banks according to the amount of cooling.
- A control method of cooling a steel according to claim 8 characterized in that said cooling control is conducted by combining a water cooling and an air cooling according to the combination of temperature curves which are based on inlet temperature FDT and out let temperature CT, respectively, the number of water poured banks are changed at the cooling zone where both cooling curves intersect with each other, and cooling is conducted according to a cooling curve which combines both cooling curves.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/JP1989/000603 WO1990015885A1 (en) | 1989-06-16 | 1989-06-16 | Steel material cooling control method |
CA000603379A CA1341247C (en) | 1989-06-16 | 1989-06-20 | Control method of cooling steel |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0453566A1 true EP0453566A1 (en) | 1991-10-30 |
EP0453566A4 EP0453566A4 (en) | 1993-03-10 |
EP0453566B1 EP0453566B1 (en) | 1998-04-08 |
Family
ID=4140238
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP89907279A Expired - Lifetime EP0453566B1 (en) | 1989-06-16 | 1989-06-16 | Steel material cooling control method |
Country Status (2)
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EP (1) | EP0453566B1 (en) |
DE (1) | DE68928639T2 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0829548A2 (en) * | 1996-09-16 | 1998-03-18 | MANNESMANN Aktiengesellschaft | Model supported process for controlled cooling of hot rolled strip or thick plate in a computer controlled rolling and cooling process |
WO2003000940A1 (en) * | 2001-06-20 | 2003-01-03 | Siemens Aktiengesellschaft | Cooling method for a hot-rolled product and a corresponding cooling-section model |
EP1111074A3 (en) * | 1999-12-23 | 2004-01-07 | SMS Demag AG | Method and device for cooling hot-rolled profiles |
WO2018116192A1 (en) * | 2016-12-20 | 2018-06-28 | Arcelormittal | A method of dynamical adjustment for manufacturing a thermally treated steel sheet |
CN110088309A (en) * | 2016-12-20 | 2019-08-02 | 安赛乐米塔尔公司 | Method for manufacturing heat-treated steel plate |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19850253A1 (en) * | 1998-10-31 | 2000-05-04 | Schloemann Siemag Ag | Method and system for controlling cooling sections |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0107237A1 (en) * | 1982-10-11 | 1984-05-02 | CENTRE DE RECHERCHES METALLURGIQUES CENTRUM VOOR RESEARCH IN DE METALLURGIE Association sans but lucratif | Method for the automatic control of the structure of rolled steel products |
-
1989
- 1989-06-16 EP EP89907279A patent/EP0453566B1/en not_active Expired - Lifetime
- 1989-06-16 DE DE68928639T patent/DE68928639T2/en not_active Expired - Fee Related
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0107237A1 (en) * | 1982-10-11 | 1984-05-02 | CENTRE DE RECHERCHES METALLURGIQUES CENTRUM VOOR RESEARCH IN DE METALLURGIE Association sans but lucratif | Method for the automatic control of the structure of rolled steel products |
Non-Patent Citations (1)
Title |
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See also references of WO9015885A1 * |
Cited By (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0829548A2 (en) * | 1996-09-16 | 1998-03-18 | MANNESMANN Aktiengesellschaft | Model supported process for controlled cooling of hot rolled strip or thick plate in a computer controlled rolling and cooling process |
EP0829548A3 (en) * | 1996-09-16 | 1998-08-05 | MANNESMANN Aktiengesellschaft | Model supported process for controlled cooling of hot rolled strip or thick plate in a computer controlled rolling and cooling process |
CN1094077C (en) * | 1996-09-16 | 2002-11-13 | 曼内斯曼股份公司 | Model supported method for controlling cooling of rolled piece during rolling and cooling |
EP1111074A3 (en) * | 1999-12-23 | 2004-01-07 | SMS Demag AG | Method and device for cooling hot-rolled profiles |
WO2003000940A1 (en) * | 2001-06-20 | 2003-01-03 | Siemens Aktiengesellschaft | Cooling method for a hot-rolled product and a corresponding cooling-section model |
US6860950B2 (en) | 2001-06-20 | 2005-03-01 | Siemens Aktiengesellschaft | Method for cooling a hot-rolled material and corresponding cooling-line models |
WO2018116192A1 (en) * | 2016-12-20 | 2018-06-28 | Arcelormittal | A method of dynamical adjustment for manufacturing a thermally treated steel sheet |
KR20190087496A (en) * | 2016-12-20 | 2019-07-24 | 아르셀러미탈 | Dynamic adjustment method for the production of thermally treated steel sheet |
CN110088309A (en) * | 2016-12-20 | 2019-08-02 | 安赛乐米塔尔公司 | Method for manufacturing heat-treated steel plate |
CN110088310A (en) * | 2016-12-20 | 2019-08-02 | 安赛乐米塔尔公司 | The method that dynamic for manufacturing heat-treated steel plate adjusts |
RU2731116C1 (en) * | 2016-12-20 | 2020-08-28 | Арселормиттал | Method for dynamic control of thermally treated steel sheet production process |
CN110088309B (en) * | 2016-12-20 | 2021-09-17 | 安赛乐米塔尔公司 | Method for manufacturing heat-treated steel sheet |
CN110088310B (en) * | 2016-12-20 | 2021-12-31 | 安赛乐米塔尔公司 | Dynamic adjustment method for manufacturing heat-treated steel sheet |
US11932916B2 (en) | 2016-12-20 | 2024-03-19 | Arcelormittal | Method of dynamical adjustment for manufacturing a thermally treated steel sheet |
Also Published As
Publication number | Publication date |
---|---|
DE68928639T2 (en) | 1998-07-30 |
EP0453566A4 (en) | 1993-03-10 |
DE68928639D1 (en) | 1998-05-14 |
EP0453566B1 (en) | 1998-04-08 |
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