JP3891067B2

JP3891067B2 - Steel pipe rolling temperature control method

Info

Publication number: JP3891067B2
Application number: JP2002223223A
Authority: JP
Inventors: 建次鳥越; 欣吾澤田; 保夫西田
Original assignee: JFE Steel Corp
Current assignee: JFE Steel Corp
Priority date: 2002-07-31
Filing date: 2002-07-31
Publication date: 2007-03-07
Anticipated expiration: 2022-07-31
Also published as: JP2004058128A

Description

【０００１】
【発明の属する技術分野】
本発明は、鋼管製造ラインにおいて鋼管を加熱し、圧延方向に多段の圧延機を連続して配した多段式連続圧延機（以下、単に圧延機ともいう。）で熱間連続圧延を行うに際しての鋼管の圧延温度制御方法に関する。
【０００２】
【従来の技術】
鋼管を製造する圧延設備では、所望の温度での圧延を行うため、圧延機の入側に加熱設備を配し、圧延機に進入する鋼管の温度を制御することが行われる。
図３は、鋼管圧延設備における従来の圧延温度制御装置の構成を示す模式図である。
【０００３】
図３において、鋼管１の圧延を行う多段式連続圧延機３の入側に加熱装置２を設け、熱間圧延のための所望の加熱を行う。従来の圧延温度制御は、多段式連続圧延機３の出側の温度が所定の温度となるように多段式連続圧延機３の入側の温度を制御することが行われており、主に、加熱装置入側温度計５、圧延機入側温度計６、圧延機出側温度計７で測定した温度を、圧延制御部10内に内在させた加熱装置制御部11の入力として加熱装置２の制御を実施するものである。ここで、加熱装置２としては、通常、誘導加熱式の加熱炉が好適に適用されるが、ガスバーナ式、電熱式等の加熱炉としてもよい。
【０００４】
【発明が解決しようとする課題】
しかしながら、圧延機の入側のみに加熱装置を配する従来の方法では、圧延機内での温度降下による圧延中の温度変化が大きく、また、その温度変化のばらつきも大きいため、例えば温間域圧延のように圧延温度の許容範囲が狭い材料では、圧延温度を許容範囲内に収めることができず、製造条件を満足できなくなる場合がある。
【０００５】
また、圧延許容温度範囲が広い材料の場合であっても、圧延機出側温度を許容範囲内に収めるためには圧延中の温度降下量分だけ圧延機入側温度を高めに設定する必要があるため、結晶粒の成長による脆化や酸化スケールの増加に伴う鋼管表面性状の悪化（例えば、表面荒れなど）が問題となる。
また、単に加熱装置出側温度を一定の目標温度となるように制御する方法では、材料（鋼管）の肉厚や搬送速度、およびデスケーラや圧延ロール冷却水の温度変動、流量変化等の外乱により、圧延機内での温度降下量が変動した場合、鋼管の圧延温度や圧延機出側温度が大きく変動することになる。
【０００６】
そのため、鋼管製品の強度、加工性等の機械的性質や表面性状が圧延機出側温度に応じて変化し、所定の温度範囲を外れる場合には品質不良にもなりかねないという問題もあった。
本発明は、上記のような品質不良を有効に回避し、精度の高い鋼管の圧延温度制御方法を提供するものである。
【０００７】
【課題を解決するための手段】
本発明は、下記各項記載の鋼管の圧延温度制御方法および装置によって上記課題を解決した。
１ . 鋼管の圧延方向に多段の圧延機を連続して配した多段式連続圧延機に適用する鋼管の圧延温度制御方法であって、該多段式連続圧延機の入側と中間部に、それぞれ鋼管を加熱する加熱装置と中間加熱装置を配してなり、加熱装置の入側、加熱装置の出側であって多段式連続圧延機の入側、中間加熱装置の入側と出側、多段式連続圧延機の出側、のそれぞれに順に、加熱装置入側温度計、圧延機入側温度計、中間加熱装置入側温度計、中間加熱装置出側温度計、圧延機出側温度計を配してなり、加熱装置入側温度計、圧延機入側温度計、中間加熱装置入側温度計で測定した鋼管温度に基づいて加熱装置の制御を行い、中間加熱装置入側温度計、中間加熱装置出側温度計、圧延機出側温度計で測定した鋼管温度に基づいて中間加熱装置の制御を行うに際し、
前記の加熱装置の制御では、前記圧延機入側温度計の測定温度が圧延許容温度範囲の上限以内となるように、また、中間加熱装置入側温度計の測定温度が圧延許容温度範囲内の所定温度となるように制御し、前記の中間加熱装置の制御では、前記中間加熱装置出側温度計の測定温度が圧延許容温度範囲の上限以内となるように、また、前記圧延機出側温度計の測定温度が圧延許容温度範囲内の所定温度となるように制御すると同時に、前記中間加熱装置出側Ｄでの鋼管温度と、前記圧延機出側Ｆでの鋼管温度が圧延許容温度範囲の下限値近傍の所定温度となるように前記加熱装置と前記中間加熱装置の加熱温度を制御することを特徴とする鋼管の圧延温度制御方法。
【０００８】
【発明の実施の形態】
図１に基づき、本発明の鋼管の圧延温度制御装置について説明する。なお、図３において説明した従来の鋼管の圧延温度制御装置と同一の部材には同一の番号を付し、ここでの再度の説明を省略する。
本発明においては、多段式連続圧延機３の中間部に中間加熱装置４を配設したことを第１の特徴とする。こうすることで、圧延機３内を通過する鋼管１の再加熱が可能となり、温度降下に伴う鋼管の温度はずれを有効に防止することを可能とすることができる。なお、本発明で行う温度制御の詳細は後述する。
【０００９】
また、本発明では、この中間加熱装置４の入側と出側に中間加熱装置入側温度計８と中間加熱装置出側温度計９を設けたことを第２の特徴とする。
そして、本発明は、加熱装置制御部11に、加熱装置入側温度計５、圧延機入側温度計６、中間加熱装置入側温度計８で測定した温度を入力して加熱装置２の制御を行い、また、中間加熱装置制御部12に、中間加熱装置入側温度計８、中間加熱装置出側温度計９、圧延機出側温度計７で測定した温度を入力して中間加熱装置４の制御を行うように構成するものである。
【００１０】
ここで、加熱装置制御部11における加熱装置２の制御では、圧延機入側温度計６の測定温度が圧延許容温度範囲の上限以内となるように、また、中間加熱装置入側温度計８の測定温度が圧延許容温度範囲内の所定温度となるように制御する。また、中間加熱装置制御部12における中間加熱装置４の制御では、中間加熱装置出側温度計９の測定温度が圧延許容温度範囲の上限以内となるように、また、圧延機出側温度計７の測定温度が圧延許容温度範囲内の所定温度となるように制御する。
【００１１】
こうすることで、圧延機を通過する鋼管の温度降下を的確に補償することが可能となり、鋼管の温度ばらつき等に起因する圧延許容温度範囲外れを解消することができ、鋼管製造における品質不良を皆無とすることができる。
次に、図２に基づき、本発明の鋼管の圧延温度制御方法（本発明例）について、比較例および従来例と対比して詳細に説明する。
【００１２】
ここで、従来例（図２（ａ））は、圧延機入側に設けた加熱装置のみで鋼管の加熱を行う例である。
一方、比較例（図２（ｂ））は、圧延機の中間部に設けた中間加熱装置で再加熱を行うようにした。比較例では、従来の加熱装置の制御に加え、中間加熱装置の出側温度が圧延許容温度範囲の上限以内の所定値となるように中間加熱装置の制御を併せて行っている。
【００１３】
また、本発明例（図２（ｃ））は、比較例の構成に加え、さらに、図１に示す５〜９の各温度計からの入力をベースとして加熱装置と中間加熱装置の温度制御を行うようにするものである。
なお、以下では、図２において、鋼管１が加熱装置２入側を通過する時点をＡとし、以下、加熱装置２出側をＢ、多段式連続圧延機３入側をＣ、中間加熱装置４入側をＤ、中間加熱装置４出側をＥ、多段式連続圧延機３出側をＦとして説明を行う。ここで、Ａ〜Ｂと、比較例と本発明例におけるＤ〜Ｅで加熱が行われる。また、Ｂ〜Ｃでは自然放冷され、さらに、Ｃ〜ＤとＥ〜Ｆでは圧延に伴う温度低下が生じる。
【００１４】
まず、図２（ａ）に基づき、従来例について説明する。
従来例では、Ａ〜Ｂのみで加熱を行うが、圧延機出側温度達成のため必然的に高温加熱が必要となり、Ｂ、Ｃにおいて圧延許容温度範囲の上限を大きく超える場合が発生する。そのため、鋼管表面に酸化スケールが生じ、表面性状が悪化し、歩留まりも低下する。また、Ｃ〜Ｆにおける圧延中の温度降下が大きく、また、ロール冷却等に起因する外乱による温度降下の変動も大きいことから、Ｆにおいて圧延許容温度範囲が外れる場合も多い。
【００１５】
一方、中間加熱装置４を配した比較例（図２（ｂ））の場合は、圧延途中でのＤ〜Ｅで再加熱を可能とすることから圧延中の温度変動幅を小さくすることができる。ただし、ＢとＥでの温度を所定の温度となるように加熱装置と中間加熱装置のそれぞれの制御を行うのみであるため、圧延条件の変動に伴う温度降下量のばらつきに起因して生じるＤとＦでの温度ばらつきを避けることができず、圧延許容温度範囲の下限を下回ってしまう場合があり、温度外れを完全には解消できていない。
【００１６】
本発明例（図２（ｃ））では、中間加熱装置により圧延中の温度変動を小さくできることに加え、ＤとＦの圧延機出側温度が圧延許容温度範囲の下限値近傍の所定温度となるように加熱装置と中間加熱装置の加熱温度を制御することから、圧延温度外れを完全に解消することができる。すなわち、本発明例では、加熱装置と中間加熱装置のそれぞれにおいて、特にＤとＦの圧延機出側温度を温度計でモニタするようにし、その温度を一定の温度に保つように制御することで、外乱の変動に応じた加熱制御を可能とし、温度外れを解消している。
【００１７】
【発明の効果】
本発明によって、圧延中の温度に対する外乱に対しても圧延機出側温度を一定に保つことができるようになり、温度外れを解消できた。また、圧延中の鋼管の温度変動幅を小さくすることができ、安定した材料特性が実現できるようになった。
【図面の簡単な説明】
【図１】本発明の鋼管の圧延温度制御装置の模式図である。
【図２】本発明例の鋼管の圧延温度制御方法について、従来例および比較例と対比して説明するグラフである。
【図３】従来の鋼管の圧延温度制御装置の模式図である。
【符号の説明】
１鋼管
２加熱装置
３多段式連続圧延機
４中間加熱装置
５加熱装置入側温度計
６圧延機入側温度計
７圧延機出側温度計
８中間加熱装置入側温度計
９中間加熱装置出側温度計
10 圧延制御部
11 加熱装置制御部
12 中間加熱装置制御部[0001]
BACKGROUND OF THE INVENTION
The present invention is for performing continuous hot rolling in a multi-stage continuous rolling mill (hereinafter also simply referred to as a rolling mill) in which a steel pipe is heated in a steel pipe production line and a multi-stage rolling mill is continuously arranged in the rolling direction. about the rolling temperature control how the steel pipe.
[0002]
[Prior art]
In a rolling facility for manufacturing a steel pipe, in order to perform rolling at a desired temperature, a heating facility is arranged on the entry side of the rolling mill, and the temperature of the steel pipe entering the rolling mill is controlled.
FIG. 3 is a schematic diagram showing a configuration of a conventional rolling temperature control apparatus in a steel pipe rolling facility.
[0003]
In FIG. 3, the heating apparatus 2 is provided in the entrance side of the multistage continuous rolling mill 3 which rolls the steel pipe 1, and the desired heating for hot rolling is performed. In the conventional rolling temperature control, the temperature on the entry side of the multistage continuous rolling mill 3 is controlled so that the temperature on the exit side of the multistage continuous rolling mill 3 becomes a predetermined temperature. The temperature measured by the heating device inlet side thermometer 5, the rolling mill inlet side thermometer 6, and the rolling mill outlet side thermometer 7 is input to the heating device control unit 11 included in the rolling control unit 10. Control is performed. Here, as the heating device 2, an induction heating type heating furnace is normally suitably applied, but a heating furnace such as a gas burner type or an electric heating type may be used.
[0004]
[Problems to be solved by the invention]
However, in the conventional method in which the heating device is arranged only on the entrance side of the rolling mill, the temperature change during rolling due to the temperature drop in the rolling mill is large, and the variation in the temperature change is also large. In the case of a material having a narrow allowable rolling temperature range as described above, the rolling temperature cannot be within the allowable range, and the manufacturing conditions may not be satisfied.
[0005]
Further, even in the case of a material having a wide rolling allowable temperature range, in order to keep the rolling mill outlet side temperature within the allowable range, it is necessary to set the rolling mill inlet side temperature higher by the amount of temperature drop during rolling. For this reason, embrittlement due to the growth of crystal grains and deterioration of the surface properties of the steel pipe (for example, surface roughness) associated with an increase in oxide scale become a problem.
In addition, the method of simply controlling the outlet temperature of the heating device to be a constant target temperature is based on disturbances such as the material thickness (steel pipe) thickness and transport speed, temperature fluctuations in the descaler and rolling roll cooling water, and flow rate changes. When the temperature drop amount in the rolling mill fluctuates, the rolling temperature of the steel pipe and the outlet temperature of the rolling mill fluctuate greatly.
[0006]
Therefore, mechanical properties such as strength and workability of steel pipe products and surface properties change according to the temperature at the exit side of the rolling mill, and there is also a problem that quality may be deteriorated if the temperature falls outside the predetermined temperature range. .
The present invention effectively avoids such poor quality as described above, there is provided a rolling temperature control how the accurate steel pipes.
[0007]
[Means for Solving the Problems]
The present invention has solved the above problems by a rolling pipe temperature control method and apparatus described in the following items.
1. A steel pipe rolling temperature control method applied to a multi-stage continuous rolling mill in which multi-stage rolling mills are continuously arranged in the rolling direction of the steel pipe . A heating device for heating a steel pipe and an intermediate heating device are arranged. The inlet side of the heating device, the outlet side of the heating device, the inlet side of the multi-stage continuous rolling mill, the inlet side and the outlet side of the intermediate heating device, multi-stage In order to each of the outlet side of the continuous rolling mill, a heating device inlet side thermometer, a rolling mill inlet side thermometer, an intermediate heating device inlet side thermometer, an intermediate heating device outlet side thermometer, a rolling mill outlet side thermometer The heating device is controlled based on the steel pipe temperature measured by the heating device inlet side thermometer, the rolling mill inlet side thermometer, and the intermediate heating device inlet side thermometer, and the intermediate heating device inlet side thermometer, intermediate Control of intermediate heating device based on steel pipe temperature measured with heating device outlet thermometer, rolling mill outlet thermometer When performing,
In the control of the heating device, the measurement temperature of the rolling mill entry side thermometer is within the upper limit of the allowable rolling temperature range, and the measurement temperature of the intermediate heating device input side thermometer is within the allowable rolling temperature range. The intermediate heating device is controlled so that the temperature measured by the intermediate heating device outlet thermometer is within the upper limit of the allowable rolling temperature range, and the rolling mill outlet temperature is controlled. At the same time, the measured temperature of the meter is controlled to be a predetermined temperature within the rolling allowable temperature range, and at the same time, the steel pipe temperature at the intermediate heating device outlet side D and the steel pipe temperature at the rolling mill outlet side F are within the rolling allowable temperature range. A method for controlling a rolling temperature of a steel pipe, wherein the heating temperature of the heating device and the intermediate heating device is controlled to be a predetermined temperature near a lower limit value .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Based on FIG. 1, the rolling temperature control apparatus of the steel pipe of this invention is demonstrated. In addition, the same number is attached | subjected to the same member as the rolling temperature control apparatus of the conventional steel pipe demonstrated in FIG. 3, and description here is abbreviate | omitted.
The first feature of the present invention is that the intermediate heating device 4 is disposed in the intermediate portion of the multi-stage continuous rolling mill 3. By doing so, the steel pipe 1 passing through the rolling mill 3 can be reheated, and the temperature deviation of the steel pipe accompanying a temperature drop can be effectively prevented. Details of the temperature control performed in the present invention will be described later.
[0009]
The second feature of the present invention is that an intermediate heating device inlet side thermometer 8 and an intermediate heating device outlet side thermometer 9 are provided on the inlet side and the outlet side of the intermediate heating device 4.
And this invention inputs the temperature measured with the heating apparatus entrance side thermometer 5, the rolling mill entrance side thermometer 6, and the intermediate heating apparatus entrance side thermometer 8 to the heating apparatus control part 11, and controls the heating apparatus 2 The temperature measured by the intermediate heating device inlet side thermometer 8, the intermediate heating device outlet side thermometer 9, and the rolling mill outlet side thermometer 7 is input to the intermediate heating device controller 12 to obtain the intermediate heating device 4. It is comprised so that control of this may be performed.
[0010]
Here, in the control of the heating device 2 in the heating device controller 11, the measured temperature of the rolling mill entry side thermometer 6 is within the upper limit of the rolling allowable temperature range, and the intermediate heating device entry side thermometer 8 is controlled. The measurement temperature is controlled to be a predetermined temperature within the rolling allowable temperature range. Further, in the control of the intermediate heating device 4 in the intermediate heating device control section 12, the measured temperature of the intermediate heating device outlet thermometer 9 is within the upper limit of the allowable rolling temperature range, and the rolling mill outlet thermometer 7 is set. The measurement temperature is controlled to be a predetermined temperature within the rolling allowable temperature range.
[0011]
By doing so, it becomes possible to accurately compensate for the temperature drop of the steel pipe passing through the rolling mill, and it is possible to eliminate out-of-roll allowable temperature range caused by temperature fluctuation of the steel pipe, etc. There can be nothing at all.
Next, based on FIG. 2, the rolling temperature control method (example of the present invention) of the steel pipe of the present invention will be described in detail in comparison with the comparative example and the conventional example.
[0012]
Here, the conventional example (FIG. 2A) is an example in which the steel pipe is heated only by the heating device provided on the rolling mill entrance side.
On the other hand, in the comparative example (FIG. 2B), reheating was performed by an intermediate heating device provided in the intermediate part of the rolling mill. In the comparative example, in addition to the control of the conventional heating device, the intermediate heating device is also controlled so that the outlet temperature of the intermediate heating device becomes a predetermined value within the upper limit of the allowable rolling temperature range.
[0013]
In addition to the configuration of the comparative example, the example of the present invention (FIG. 2 (c)) further controls the temperature of the heating device and the intermediate heating device based on inputs from the thermometers 5 to 9 shown in FIG. Is what you want to do.
In the following, in FIG. 2, the point in time when the steel pipe 1 passes the inlet side of the heating device 2 is A, and the outlet side of the heating device 2 is B, the inlet side of the multistage continuous rolling mill 3 is C, and the intermediate heating device 4 Description will be made assuming that the entry side is D, the intermediate heating device 4 exit side is E, and the multi-stage continuous rolling mill 3 exit side is F. Here, heating is performed by A to B and D to E in the comparative example and the present invention example. Moreover, in B-C, it naturally cools, and also in C-D and E-F, the temperature fall accompanying rolling arises.
[0014]
First, a conventional example will be described with reference to FIG.
In the conventional example, heating is performed only with A to B, but high temperature heating is inevitably necessary to achieve the rolling mill outlet temperature, and in B and C, the upper limit of the allowable rolling temperature range may be greatly exceeded. Therefore, an oxide scale is generated on the surface of the steel pipe, the surface properties are deteriorated, and the yield is also reduced. Moreover, since the temperature drop during rolling in C to F is large, and the fluctuation of the temperature drop due to disturbance due to roll cooling or the like is also large, the allowable temperature range for rolling is often out of F.
[0015]
On the other hand, in the case of the comparative example (FIG. 2 (b)) in which the intermediate heating device 4 is disposed, the temperature fluctuation range during rolling can be reduced because reheating is possible by D to E during rolling. . However, since only the control of the heating device and the intermediate heating device is performed so that the temperatures at B and E become a predetermined temperature, D generated due to variations in the temperature drop due to fluctuations in rolling conditions. And F cannot be avoided, and the temperature may fall below the lower limit of the allowable rolling temperature range, and the temperature deviation cannot be completely eliminated.
[0016]
In the example of the present invention (FIG. 2 (c)), in addition to being able to reduce the temperature fluctuation during rolling by the intermediate heating device, the rolling mill outlet temperature of D and F becomes a predetermined temperature near the lower limit value of the allowable rolling temperature range. Thus, since the heating temperatures of the heating device and the intermediate heating device are controlled, it is possible to completely eliminate the rolling temperature deviation. That is, in the example of the present invention, in each of the heating device and the intermediate heating device, the temperature at the outlet side of the rolling mill of D and F is monitored with a thermometer, and the temperature is controlled to be maintained at a constant temperature. Heating control according to fluctuations in disturbance is made possible and temperature deviation is eliminated.
[0017]
【The invention's effect】
According to the present invention, it becomes possible to keep the temperature at the exit side of the rolling mill constant against disturbance with respect to the temperature during rolling, thereby eliminating the temperature deviation. In addition, the temperature fluctuation range of the steel pipe during rolling can be reduced, and stable material characteristics can be realized.
[Brief description of the drawings]
FIG. 1 is a schematic view of a rolling temperature control device for a steel pipe according to the present invention.
FIG. 2 is a graph for explaining a rolling temperature control method for a steel pipe of an example of the present invention in comparison with a conventional example and a comparative example.
FIG. 3 is a schematic view of a conventional rolling temperature control device for steel pipes.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steel pipe 2 Heating device 3 Multistage continuous rolling mill 4 Intermediate heating device 5 Heating device entrance side thermometer 6 Rolling mill entrance side thermometer 7 Rolling mill exit side thermometer 8 Intermediate heating device entrance side thermometer 9 Intermediate heating device exit side thermometer
10 Rolling control unit
11 Heating device controller
12 Intermediate heating device controller

Claims

A steel pipe rolling temperature control method applied to a multi-stage continuous rolling mill in which multi-stage rolling mills are continuously arranged in the rolling direction of the steel pipe,
A heating device and an intermediate heating device for heating the steel pipe are arranged on the entry side and the intermediate portion of the multi-stage continuous rolling mill,
Enter the heating device in order of the inlet side of the heating device, the outlet side of the heating device and the inlet side of the multi-stage continuous rolling mill, the inlet side and outlet side of the intermediate heating device, and the outlet side of the multi-stage continuous rolling mill, respectively. Side thermometer, rolling mill inlet side thermometer, intermediate heating device inlet side thermometer, intermediate heating device outlet side thermometer, rolling mill outlet side thermometer,
Control the heating device based on the steel pipe temperature measured with the heating device inlet side thermometer, rolling mill inlet side thermometer, intermediate heating device inlet side thermometer,
When controlling the intermediate heating device based on the steel pipe temperature measured with the intermediate heating device inlet side thermometer, intermediate heating device outlet side thermometer, rolling mill outlet side thermometer ,
In the control of the heating device, the measured temperature of the rolling mill entry side thermometer is within the upper limit of the allowable rolling temperature range, and the measured temperature of the intermediate heating device input side thermometer is within the allowable rolling temperature range. The intermediate heating device is controlled so that the temperature measured by the intermediate heating device outlet side thermometer is within the upper limit of the allowable rolling temperature range, and the rolling mill outlet side temperature is controlled. At the same time, the measurement temperature of the meter is controlled to be a predetermined temperature within the rolling allowable temperature range,
The heating temperature of the heating device and the intermediate heating device so that the steel tube temperature on the outlet side D of the intermediate heating device and the steel tube temperature on the outlet side F of the rolling mill become a predetermined temperature near the lower limit value of the allowable rolling temperature range. A method for controlling the rolling temperature of a steel pipe, characterized in that: