JPH0510410B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a furnace temperature control method for a continuous heating furnace that is disposed upstream of a hot rolling line and heats steel materials.

[Prior Art] A heating furnace is disposed at the most upstream side of a hot rolling line for steel materials, and red-hot steel passes through each rolling mill downstream of the line to become a product. For example, in a rolling line for seamless steel pipes, a piercing mill (hereinafter referred to as a piercer), a stretching mill (mandrel), and a reducing mill (stretch reducer) are placed downstream of a rotary continuous heating furnace, or a piercer, Elongator, plug mill, reeling mill and sizing mill are located.

A method of determining the optimum extraction cycle time of the heating furnace in accordance with the cycle time of the rolling mill in the above-mentioned hot rolling line has already been proposed by the present applicant in Japanese Patent Application No. 60-265073.

On the other hand, many control technologies for heating furnaces have been proposed. For example, in Japanese Patent Publication No. 58-25731, the temperature at representative positions in the furnace is determined in a heating pattern using the furnace time as a parameter for multiple steel types. The furnace temperature is set based on this calculation. In addition, in Special Publication No. 57-53846,
A method for controlling furnace temperature when a downstream rolling line is temporarily stopped is disclosed.

[Problems to be Solved by the Invention] However, Japanese Patent Application No. 60-265073 proposes an optimal cycle for supplying steel from the heating furnace to the rolling mill line on the premise that the extraction temperature of the steel from the heating furnace is at an appropriate temperature. It does not mention the furnace temperature control of the heating furnace corresponding to this optimum cycle time. In addition, special public service 1983-
Although the conventional heating furnace control methods described in Japanese Patent Publication No. 25731 and Japanese Patent Publication No. 57-53846 are excellent methods in terms of control accuracy and energy saving, they do not take into account the balance with the rolling line.

To explain in more detail, the cycle time of a rolling line varies greatly depending on the steel lot, and especially when processing small lots continuously, it is necessary to take into account the stop time between lots, so it is necessary to raise the temperature in advance. Traditional methods of setting patterns cannot accommodate rolling line cycle time variations.

The present invention is capable of responding to the extraction pitch while maintaining the optimum extraction cycle time of the heating furnace in accordance with the cycle time of the rolling line by controlling the extraction pitch and furnace temperature of the heating furnace in a short time and with high precision. An object of the present invention is to provide a heating furnace control method that controls the furnace temperature of a heating furnace and reduces thermal energy loss.

[Means for Solving the Problems] The present invention sequentially heats steel materials using a plurality of combustion control zones disposed upstream of a hot rolling line, and heats the steel materials heated to a target temperature at the downstream rolling line cycle time. A furnace temperature control method for a continuous heating furnace that enables extraction at the corresponding extraction pitch, (A) Calculate the cycle time for each combustion control zone of the heating furnace, and The maximum value of the current cycle time of the side equipment is set as the extraction pitch of the heating furnace, and the extraction time of each steel material from the heating furnace is set. From the temperature in the control zone, the time t until each steel material is extracted from the combustion control zone, and the target temperature θ _rk of each steel material on the exit side of the combustion control zone, the furnace temperature θ of the combustion control zone is calculated. _si is set.

[Effect] According to the present invention, the following effects are achieved.

While conventional furnace temperature setting means basically require predictive calculation of the steel material temperature up to the extraction point of the continuous heating furnace, it is only necessary to perform predictive calculation up to the exit side of each combustion control zone, which makes the predictive calculation easier. The calculation time is greatly reduced, making it easy to realize and achieve the method. Furthermore, no matter what method of prediction calculation is used, the calculation accuracy deteriorates as the time for prediction increases. Therefore, the method disclosed herein only needs to perform calculations within each combustion control band, and is also advantageous in terms of prediction accuracy.

When configuring the furnace temperature setting means, the extraction time or extraction cycle time is a variable that is repeatedly calculated as a hypothetical variable in the furnace temperature setting means, or a variable given in advance from the furnace temperature setting means. It is customary to have In contrast, the setting means of the present invention sets the cycle time of the continuous production line as the extraction cycle time, whichever is larger among the cycle time τ _h of each combustion control zone and the current cycle time τ _n of the equipment on the downstream side of the heating furnace. This can be determined quite rationally from a balancing perspective. Therefore, it is possible to automatically determine the extraction cycle time of a continuous heating furnace and to achieve consistency with the method of achieving automatic operation of the above-mentioned equipment.

[Example] FIG. 1 is a schematic diagram showing a control system of the present invention.

That is, the present invention provides industrial control computer 11
The extraction cycle time control device 12, the furnace temperature control device 13, the industrial control computer 11, and the transmission device 14 that connects the respective control devices 12 and 13 are used.

The industrial control computer 11 includes a cycle time calculating section 1 of a rolling mill/processing machine, a steel material grasping section 2 that grasps the position and type of steel on all rolling lines in real time, and a steel material grasping section 2 that calculates the temperature of steel in the heating furnace. A temperature calculation unit 3, a steel material temperature prediction unit 4 that predicts the temperature of the steel in the heating furnace at each hour until it is extracted, a soaking zone furnace cycle time setting unit 5, and a heating zone furnace cycle time setting unit 6. An operating system 21 is provided which includes an extraction cycle time setting section 7 and a heating furnace temperature setting section 8, and which orders the operations of the respective sections 1 to 8 and exchanges information.

The operations of the above-mentioned sections 1 to 8 of the industrial control computer 11 are as follows.

The cycle time calculation unit 1 of the rolling mill/processing machine is
The steel material grasping section 2, which grasps the location and type of steel materials on all rolling lines in real time, receives information such as the lot of steel material on the line, the type of steel material, length, weight, shape, rolling or processing conditions, etc. Calculate the rolling time and processing time required for each rolling mill/processing machine. For example, Vr: rolling speed, Ls: length of steel material, k1, k2: constant, D: roll diameter of rolling mill,
When N is the roll rotation speed of the rolling mill, the rolling time τ can be calculated as follows: τ=k1, Ls/Vr, Vr=k2·D·N.

The steel material grasping unit 2, which grasps the position and type of steel materials on all rolling lines in real time, uses the steel material tracking function possessed by the industrial control computer 11 to check the current position of steel materials on all rolling lines, including inside the heating furnace. and each steel material lot, steel type, length,
Grasp changes in the weight, shape, rolling or processing conditions, rolling/processing history, etc. in real time from moment to moment. Here, the industrial control computer 11
is a means (sensor, etc.) placed throughout the rolling line to detect whether steel is present at that location.
The steel material is tracked by logically determining the causal relationship between the detection signals. Further, it is assumed that information such as the lot, steel type, length, weight, etc. of each steel material to be carried into the line has been input in advance.

The steel material temperature calculating section 3, which estimates and calculates the temperature of the steel material in the heating furnace, obtains the current position, steel type, length, Knowing the shape and also knowing the current furnace temperature from the furnace temperature control device 13, an estimation calculation is performed on the temperature of the steel material in the furnace every unit time. The method of estimation calculation is, for example, the Japanese Patent Publication No. 57-53848.
The well-known difference method or finite element method is used as described in Japanese Patent Publication No. 61-1484.

The steel material temperature prediction section 4 calculates the temperature of the steel material for each unit time between the current temperature of the steel material obtained by the steel material temperature calculation section 3 which calculates the temperature of the steel material in the heating furnace and the future time required for prediction. By predicting and calculating the position in the furnace, the temperature of the steel material for each unit time in the future until extraction is calculated. The predicted position is calculated based on the assumption of the in-furnace conveyance cycle time, the moving distance per cycle time, and the time required for changing the rolling mill/processing machine between multiple lots. The moving distance and changeover time per cycle time are determined by the steel material grasping section 2, which grasps the location and type of steel materials on all rolling lines in real time.
It can be calculated from the information held by The in-furnace conveyance cycle time assumed here is the heating zone furnace cycle time if the prediction range targets steel materials existing in the heating zone, and the soaking zone furnace cycle time if the prediction range targets steel materials existing in the soaking zone. This is a value that is a candidate for time. The temperature prediction calculation is performed using the same method as the steel material temperature calculating section 3 that calculates the steel material temperature in the heating furnace or a simplified method.

The soaking furnace cycle time setting section 5 compares the predicted value of the steel material temperature at the extraction position obtained by the steel material temperature prediction section 4 with the heating furnace extraction reference temperature, and adjusts the in-furnace conveyance cycle time of the steel material. The minimum in-furnace transfer cycle time at which the predicted temperature value at the extraction position of the steel existing in the soaking zone reaches the heating furnace extraction reference temperature is determined, and this is defined as the soaking zone furnace cycle time. The heating furnace extraction reference temperature can be calculated from information held by the steel material grasping section 2 that grasps the location and type of steel materials on all rolling lines in real time.

The heating zone furnace cycle time setting unit 6 compares the predicted steel temperature at the heating zone outlet position obtained by the steel temperature prediction unit 4 with the heating zone outlet reference temperature, adjusts the in-furnace conveyance cycle time of the steel, The minimum in-furnace conveyance cycle time at which the predicted value of the steel material temperature at the heating zone exit position of the steel existing in the heating zone reaches the heating zone exit reference temperature is determined, and this is determined as the heating zone furnace cycle time. The heating zone outlet reference temperature can be calculated from information held by the steel material grasping section 2 that grasps the position and type of steel materials on all rolling lines in real time.

The extraction cycle time setting section 7 includes a rolling mill/processing machine cycle time calculation section 1, a steel material grasping section 2 that grasps the position and type of steel on all rolling lines in real time, a soaking furnace cycle time setting section 5, and a heating zone. This is a function to obtain the extraction cycle time from the result of the furnace cycle time setting section 6. This determines the extraction cycle time based on the method of Japanese Patent Application No. 60-265073. However, the cycle time of the heating furnace shall be the larger of the heating zone furnace cycle time and the soaking zone furnace cycle time. That is, for each lot of steel products, the arrival time from the heating furnace to the entry side of each rolling mill/processing machine and the arrival time to the exit side are calculated based on the cycle time calculation unit 1 of the rolling mill/processing machine and the position of the steel products on all rolling lines. It is calculated by determining the rolling time/processing time and transport time using the steel material grasping section 2 that grasps the type in real time. Then, the arrival time of the next extracted steel material to the entry side of each rolling mill/processing machine is equal to or greater, and the arrival time of the next extracted steel material is equivalent to the arrival time of the above-mentioned next extracted steel material with respect to one or more rolling mills/processing machines. The larger value of the mill cycle time and the cycle time of the heating furnace is determined as the extraction cycle time. Then, this value is sent to the extraction cycle time control device 1 via the operating system 21 of the industrial control computer 11 and the transmission device 14.
Transmit to 2.

The furnace temperature setting section 8 of the heating furnace includes a soaking zone furnace cycle time setting section 5 and a heating zone furnace cycle time setting section 6.
The heating zone furnace temperature set value and the soaking zone furnace temperature set value are determined from the partially modified function and the mill cycle time determined by the extraction cycle time setting section 7. That is,
The furnace temperature setting value for the soaking zone is determined by the soaking zone furnace cycle time setting section 5, which calculates the extraction cycle time based on the current actual furnace temperature, which is then converted into the furnace conveyance cycle time to the mill cycle time. The function is changed to a function that fixes the match, adjusts the soaking zone furnace temperature set value, and calculates the set value that is the minimum setting. This function is performed by the soaking furnace cycle time setting section 5.
The furnace temperature, which is a known parameter, is taken as an unknown parameter, and the in-furnace transfer cycle time, which is an unknown parameter, is taken as a known parameter. Further, the heating zone furnace temperature set value is determined by the heating zone furnace cycle time setting section 6, which calculates the heating zone furnace cycle time based on the current actual furnace temperature. The in-furnace conveyance cycle time is fixed to match the soaking zone furnace cycle time, the heating zone furnace temperature set value is adjusted, and the function is changed to find the set value that is the minimum setting to find the set value. In this function, the furnace temperature, which is a known parameter in the heating zone furnace cycle time setting section 6, is used as an unknown parameter, and the in-furnace conveyance cycle time, which is an unknown parameter, is used as a known parameter. Here, as is well known, when the furnace temperature set value is changed, the furnace temperature does not immediately match the set value, and it takes time for it to match. When the above-mentioned furnace temperature set value is given, if you directly replace it with the furnace temperature, you are ignoring this fact, so the furnace temperature θ(t) required for calculation is, for example, the furnace temperature set value. From θset, the elapsed time t since the setting change, and the furnace load M, it is given as θ(t)=f(θset, M, t). The heating zone furnace temperature set value and soaking zone furnace temperature set value thus determined are calculated by the industrial control computer 11.
operating system 21, transmission device 14
It is transmitted to the furnace temperature control device 13 via.

An embodiment in which the present invention is applied to a seamless steel pipe manufacturing line shown in FIG. 2 will be described below. In FIG. 2, 31 is a heating furnace, 32 is a piercer, 33 is a mandrel mill, 34 is a reheating furnace, and 35 is a stretch reducer. That is, a heating furnace (rotary hearth type steel material heating furnace) 31 is installed at the beginning of the manufacturing process, and the steel material 51 is heated thereby. As shown in FIG. 3, this heating furnace is composed of five zones, with zones 1 to 3 serving as heating zones, and zones 4 and 5 serving as soaking zones. A thermocouple 41 is installed in each zone to measure the furnace temperature of each zone, and the furnace temperature control device 13 of each zone calculates the temperature calculated by the industrial control computer 11 based on the method described above via the transmission device 14. The combustion amount of the combustion device 42 installed in each zone is controlled so that the furnace temperature is set. The measured furnace temperature is transmitted to the industrial control computer 11 via the transmission device 14.

The steel material for seamless steel pipes depends on the steel type of the product,
They vary by size and length and are grouped together as a lot. It is the steel material grasping section 2 of the industrial control computer 11 that grasps the steel materials in the furnace (A, . . . Now, as shown in Figure 3, there are A, B,..., F in the heating furnace.
It is assumed that the steel material 51 of lot A is being heated and that lot A is being rolled in the rolling line. At this time, A
The cycle time of the rotor's rolling mill and processing machine is τ _n,A , and the current heating zone furnace cycle time is τ _h = max.
(τ _h1 , τ _h2 , τ _h3 ), the soaking furnace cycle time is τ _s
=
max(τ _s4 , τ _s5 ), the extraction pitch is max(τ _{nA ,} τ h , τ nA , τ _h ,
τ _s ), and this value is sent to the extraction cycle time controller 12 via the transmission device 14 (τ _hi is the i-zone heating zone furnace cycle time, i=1,
2, 3, τ _sj is the j-band soaking furnace cycle time,
j=4, 5,). Extraction cycle time control device 12
operates the hearth drive device 43 and steel extraction device 44 at this pitch.

Note that the above-mentioned τ _nA , τ _h , τ _s , max(τ _nA , τ _h , τ _s
)
is calculated by the industrial control computer 11 as follows.

The cycle time τ _n,A of the A-lot rolling mill processing machine is calculated by the cycle time calculating section 1 of the rolling mill processing machine based on the information of the steel material gripping section 2.

The heating zone furnace cycle time τ _h is such that zones 1 to 3 of the heating furnace are heating zones, and each cycle time is calculated by the heating furnace cycle time setting unit 6. In calculating this, the steel material temperature calculating section 3 and the steel material temperature predicting section 4 are used to find the cycle time that satisfies the heating zone exit reference temperature as described above. These are the cycle times τ _h1 , τ _h2 , τ _h3 for heating furnace zones 1 to 3, and τ _h is max(τ _h1 , τ _h2 , τ _h3
). The heating furnace cycle time setting unit 6 also takes the maximum value of these three values.

The soaking furnace cycle time τ _s is such that the heating furnaces 4 and 5 are soaking zones, and each cycle time is calculated by the soaking zone furnace cycle time setting unit 5. In calculating this, the steel material temperature calculating section 3 and the steel material temperature predicting section 4 are used to find the cycle time that satisfies the heating zone exit reference temperature as described above. This is the cycle time τ _s4 for soaking zones 4 and 5,
τ _s5 , and τ _s is determined as max(τ _s4 , τ _s5 ). The soaking furnace cycle time setting section 5 also takes the maximum value of these two values.

It is the extraction cycle time setting unit 7 that determines the extraction pitch as max (τ _n,A , τ _h , τ _s ).

Under such circumstances, the furnace temperature setting value θ _si (i=1, . . . , 5) for each i-band is determined as follows according to the present invention. Now in the 5th zone there are A _{, 5} , _{B, 5} , B, ₄ in the 4th zone, C _{, 4 in the C} , and D in the 3rd zone. There are n _D,3 lots, n _E,2 E lots in the 2nd zone, and n _F,1 F lots in the 1st zone.For simplicity, the outlet reference temperature of each i zone is θ _rk ( k=
1,...,5) (Originally, _θrk differs depending on the lot). Here, the time t until the final 5-zone material is extracted is determined by the position in the furnace and the cycle time calculation unit 1 of the rolling mill/processing machine as τ _n,A , τ _n,B , and A,
From the stop time τ _AB between B lots, n _A,5・τ _n,A + τ _AB
+n _B,5・τ _n,B , and the average value is t/(n _A,5 +
n _B,5 ) (≡τ _M,5 ). τ _M,5 and current max
Compare (τ _h , τ _s ) (≡τ _F ), and if τ _M,5 > τ _F , then
Since the extraction cycle time of the steel material to be extracted from the heating furnace is the rolling cycle time τ _{M ,5, the 5-zone furnace temperature setting value θ s} ,5 is determined by setting τ _s,5 = τ _M,5 at this cycle time. It is determined so that the steel material present in the 5th zone reaches the target temperature θ _r,5 at the outlet side of the 5th zone, that is, at the extraction port. At this time, τ _M,5 = τ _s,5 . On the other hand, if τ _M,5 < τ _F , θ _s,5 is determined in the same way, but the calculated result θ _s,5 may exceed the maximum allowable furnace temperature, and in this case, θ _s When _,5 is the highest furnace temperature setting and θ _s,5 is the furnace temperature, let τ _s ,5 be the cycle time at which the temperature of the steel materials in all five zones becomes θ _r,5 or higher at the extraction port. . At this time, τ _M,5 <τ _s,5 , and the line balance is inevitably disturbed.

The function of determining the furnace temperature setting values for the five zones described above is performed by the heating furnace furnace temperature setting section 8 in the computer 11. At this time, the A to F lots in the furnace, their positions and numbers are obtained from the steel material grasping section 2. The cycle times τ _n,A of the rolling mills and processing machines of these lots are obtained from the cycle time calculating section 1 of the rolling mill processing machines. Inter-lot stoppage values such as τ _AB are also obtained from the cycle time calculating section 1 of the rolling mill processing machine. From these, the time t and the average value τ _M,5 until the final material of 5 zones is extracted are calculated by the heating furnace furnace temperature setting section 8. Furthermore, the heating furnace furnace temperature setting section 8 compares this τ _M,5 with max (τ _h , τ _s ), and changes the furnace temperature. Furthermore, if τ _M,5 > τ _F , the heating furnace furnace temperature setting section 8 sets τ _s,5 = τ _M,5 , and uses the steel material temperature grasping section 2 and the steel material temperature prediction section 4 to set the 5-zone setting furnace. The temperature θ _s,5 is determined so that the steel material temperature matches θ _r,5 on the exit side of the 5th zone.
In the opposite case where τ _M,5 <τ _F , the correspondence between the internal functions of the industrial control computer 11 is the same.

The above description has been made regarding the determination of the furnace temperature setting values for the 5 zones, but the correspondence of the internal functions of the industrial control computer 11 is the same for the furnace temperature settings for the 4th to 1st zones.

Hereinafter, for the four-zone furnace temperature setting value, a furnace temperature setting value such that τ _s,4 matches max (τ _M,5 , τ _s,5 ) is determined. That is, when the extraction pitch is set to max (τ _M,5 , τ _s,5 ),
Find θ _s,4 at which the temperature of all 4-band pressure steel materials is equal to or higher than θ _r, 4 on the 4-band exit side. If this calculation result exceeds the allowable maximum furnace temperature setting value, the temperature of all four steel strips when θ _s,4 is the maximum furnace temperature setting value and θ _s, 4 is the furnace temperature. Let θ _{s,4 be the cycle time at which θ r, 4} or more occurs on the 4-band output side.

The function of determining the furnace temperature set values for the four zones described above is performed in the computer 11 as follows.
That is, τ _M,5 and τ _s,5 have already been calculated at the stage of setting the furnace temperature in the five zones described above. Here, the time for the final steel material of the 4th zone to reach the exit side of the 4th zone is determined by the heating furnace furnace temperature setting section 8 in the same manner as described for the 5th zone. below,
When the furnace temperature is set to θ _s,4, the steel material temperature θ _r,4 on the exit side of the 4th band is determined by the steel material temperature prediction unit 4 . and θ _s,4 is 4
If the furnace temperature is calculated to be higher than the allowable furnace temperature that can be set in the belt, the cycle time that satisfies the steel material temperature θ _r,4 when heating is performed at the furnace temperature setting of this upper limit value is determined as γ _s,4 . This is performed by the heating furnace furnace temperature setting section 8.

For bands 3 to 1, max(τ _{M,5 , τ s , 5} ,
In order for τ _s,4 , τ _h,3 ) and τ _h,2 to match, in one band,
Similarly, θ s,3 , θ s,2 , θ s, so that max(τ _M,5 , τ _s,5 , τ _s,4 , τ _{h,3 ,} τ _{h,2 )} and τ _{h ,1} match Find ₁ .

Here, as an example, the furnace temperature setting method will be explained in more detail in the case of four zones. τ _s,4 = max
(τ _M,5 , τ _s,5 ). Then, for example, the final steel material of the 4th zone will be n _B,5・τ _s,4 by the time it reaches the exit side of the 4th zone.
It takes +τ _BC +n _c・τ _s,4 time. τ _BC is lot B
This is the time that occurs between C and C. At this time, assuming that the furnace temperature of this steel material is θ _s,4 , the temperature at the exit side of the 4th zone can be predicted and determined whether it is higher than θ _r,4 . The same thing is done for all the steel materials in the four bands, and the furnace temperature θ s _,4 is determined so as to satisfy θ _r,4 . If it is found that θ _s,4 is higher than the allowable furnace temperature setting value for 4 zones, then θ _s,4 is set to the maximum value, and when heated at that furnace temperature, all of the 4 zones Find the cycle time τ _{s, 4 at which the steel material reaches a temperature of θ r,} 4 or higher.

In addition, in the explanation of the above embodiment, the variables τ _h,1 ,
The cycle times τ _h,2 , τ _h,3 , τ _s,4 , and τ _s,5 are the cycle times for calculating the furnace temperature setpoint, which assumes a furnace temperature different from the current furnace temperature. It is something. On the other hand, the cycle times τ _h1 , τ _h2 , τ _h3 , τ _s4 , and τ _s5 that determine the extraction pitch are calculated based on the current actual furnace temperature, and are the same as the previous ones τ _h,1 , τ _h,2 , τ _h,3 , τ _s,4 , τ _s,
Does not match ₅ (it is a different variable).

The cycle time of each combustion control zone based on the present invention changes in the next calculation cycle because the actual furnace temperature changes due to the furnace temperature change based on the furnace temperature setting method also based on the present invention. Therefore, since the furnace cycle time τ _F changes, each furnace temperature set value θ _s,i
is changing.

The industrial control computer 11 performs the above furnace temperature setting method at regular intervals (here, every 3 minutes) and outputs the set value. That is, the operating system 21 of the computer 11 specifies that each part 1 to 8 of the computer 11 satisfies the above-described execution order, and adjusts so that the same processing is performed at regular intervals.

FIG. 4 shows an example of a comparison between this method of setting the furnace temperature and the state of temperature rise of steel materials obtained manually by a conventional operator. This is for a billet with a diameter of 175φmm and a length of 2.5m, and although the results vary considerably depending on the condition of the lot in the furnace, overall energy savings are achieved due to post-heating compared to manually setting the furnace temperature. has been done. Furthermore, as shown in Table 1, the furnace temperature is now set lower than before. Fuel costs also fell by about 4%.

As described above, the furnace temperature setting method according to the present invention determines the furnace temperature according to the takt time of the processing machines and rolling mills after the heating furnace, so it is easy to balance the line including the heating furnace. In general, line balancing in the manufacturing process is said to be the key to maximizing production efficiency and reducing energy loss due to waiting time and the like. In this sense, the method of the present invention can be said to be an unprecedented furnace temperature setting method that minimizes energy loss without lowering production efficiency.

In the present invention, setting the maximum value of the cycle time as the extraction pitch is connected to setting the furnace temperature in the combustion control zone as follows. That is, the cycle time of each combustion control zone based on the present invention changes in the next calculation cycle because the actual furnace temperature changes due to the furnace temperature change based on the furnace temperature setting method also based on the present invention. Therefore, since the furnace cycle time τ _F changes, each furnace temperature setting value θ _s,i changes. By setting the maximum value of the cycle time as the extraction pitch, the rolling line (including the heating furnace) satisfies the constraints for both the heating conditions and the rolling processing conditions.
In this state, the heating furnace cycle time τ _F is determined based on the current temperature inside the heating furnace, and this τ _F determines the
As described in (3), the furnace temperature setting value θ _s,i for each zone is determined.

At this time, attention is paid to the magnitude relationship between τ _F and τ _h,1 , τ _h,2 , τ _h,3 , τ _s,4 , and τ _s,5 .

For example, if τ _M,5 > τ _F in the calculation results of a certain calculation cycle, τ _s,5 = τ _M,5 > τ _F = max(τ _n,
A ,
τ _h , τ _s ), the action works to increase the furnace temperature set value θ _s,5 .

If τ _M,5 < τ _F then τ _F = max(τ _n,A , τ _h , τ _s )
＞
Since τ _M,5 = τ _s,5 , an action is taken to lower the furnace temperature set value θ _s,5 .

As a result, in the next calculation cycle, in the above case, assuming that other conditions do not change due to the increase in the furnace temperature setting, τ _F should be a smaller value than the previous calculation result. Therefore, τ _F and τ _M,5
The difference will be reduced. Conversely, in the above case, τ _F is considered to be a larger value than the previous time, so the difference between τ _F and τ _M,5 is reduced. By repeating this, τ _F ≒ τ _M,5 and an appropriate heating furnace temperature is set. Similarly, for bands 4 to 1, τ _s,5 ≒
τ _s,4 , τ _s,4 ≒τ _h,3 ...and the ideal figure τ _F ≒τ _M,5 ≒
τ _s,4
It is controlled in an autonomous decentralized manner to approach ≒τ _h,3 ≒τ _h,2 ≒τ _h,1 . This is because a state in which the above equation holds true is a state in which the above-mentioned line balance is achieved, and this control method is a method that can achieve this.

[Effects of the Invention] As described above, according to the present invention, by controlling the extraction pitch and furnace temperature of the heating furnace in a short time and with high precision, the optimum extraction cycle of the heating furnace can be adjusted in accordance with the cycle time of the rolling line. It is possible to control the furnace temperature of the heating furnace in accordance with the extraction pitch while maintaining the extraction time, thereby obtaining a method of controlling the heating furnace with less thermal energy loss.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the control system of the present invention, Figure 2 is a schematic diagram showing the control system of the present invention.
The figure is a schematic diagram showing a seamless steel pipe production line, and Figure 3 is a control system diagram showing a furnace temperature control system for a heating furnace.
FIG. 4 is a diagram showing the state of steel material temperature rise. 11... Industrial control computer, 12... Extraction cycle time control device, 13... Furnace temperature control device.

【table】

Claims (1)

[Claims] 1 Continuous heating that sequentially heats the steel material using multiple combustion control zones placed upstream of the hot rolling line, and allows the steel material heated to a target temperature to be extracted at an extraction pitch corresponding to the downstream rolling line cycle time. A furnace temperature control method, which involves (A) calculating the cycle time for each combustion control zone of the heating furnace, and calculating the maximum value between the cycle time of all combustion control zones and the current cycle time of the downstream equipment of the heating furnace; (B) For each combustion control zone of the heating furnace, determine the temperature of each steel within the combustion control zone and the temperature of each steel. The furnace temperature θ _si of the combustion control zone is set from the time t from the combustion control zone until the end of passing through the control zone and the target temperature θ _rk of each steel material on the exit side of the combustion control zone. Furnace temperature control method for continuous heating furnace.