JP6260448B2 - Heat treatment equipment for hot-rolled steel strip - Google Patents

Heat treatment equipment for hot-rolled steel strip Download PDF

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JP6260448B2
JP6260448B2 JP2014098681A JP2014098681A JP6260448B2 JP 6260448 B2 JP6260448 B2 JP 6260448B2 JP 2014098681 A JP2014098681 A JP 2014098681A JP 2014098681 A JP2014098681 A JP 2014098681A JP 6260448 B2 JP6260448 B2 JP 6260448B2
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steel strip
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rolled steel
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JP2015214733A (en
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木村 幸雄
幸雄 木村
松原 行宏
行宏 松原
高橋 秀行
秀行 高橋
彩子 田
彩子 田
俊郎 岡崎
俊郎 岡崎
直樹 中田
直樹 中田
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JFE Steel Corp
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Description

本発明は、熱間圧延から冷間圧延を経て高強度鋼板を製造する過程で、冷間圧延に先立って熱延鋼帯を軟質化するための熱処理を施す熱処理設備に関し、詳しくは、熱処理に要する時間を適正に確保し、しかも能率良く熱延鋼帯を軟質化することが可能な熱処理設備に関するものである。   The present invention relates to a heat treatment facility for performing a heat treatment for softening a hot-rolled steel strip prior to cold rolling in the process of producing a high-strength steel sheet from hot rolling to cold rolling. The present invention relates to a heat treatment facility that can appropriately secure the time required and can efficiently soften a hot-rolled steel strip.

近年、自動車用鋼板等の様々な分野で、高強度の鋼板(いわゆるハイテン材)が広く用いられるようになり、用途に応じた種々のハイテン材が開発されている。ところがハイテン材は、強度を高めるための合金成分を多く含有しているので、熱間圧延の後の冷却過程で硬質な低温変態相(たとえばベイナイトやマルテンサイト等)が生成し、ハイテン材に加工を加える際の変形抵抗が大きくなる。   In recent years, high-strength steel plates (so-called high-tensile materials) have been widely used in various fields such as automotive steel plates, and various high-tensile materials have been developed according to applications. However, high-tensile materials contain many alloy components to increase strength, so that a hard low-temperature transformation phase (for example, bainite and martensite) is generated in the cooling process after hot rolling, and processed into high-tensile materials. The deformation resistance when adding is increased.

ハイテン材の中でも特に、高強度の冷延鋼板(以下、高強度鋼板という)を製造する際には、素材となる熱延鋼帯の変形抵抗が大きく、しかも板厚を従来よりも薄く圧下するので、冷間圧延の負荷が増大する。その結果、冷間タンデム圧延機を複数回通板させて、冷間圧延のパス数を増やす必要が生じるばかりでなく、圧延中に破断等のトラブルが発生し易くなり、冷間タンデム圧延機の稼動率が低下し、ひいては高強度鋼板の生産性が低下するという問題が生じる。また、熱延鋼帯の変形抵抗が大きいので、冷間圧延によって得られる高強度鋼板の形状が劣化し、歩留りの低下を招くという問題もある。   Especially when manufacturing high-strength cold-rolled steel sheets (hereinafter referred to as high-strength steel sheets) among high-tensile materials, the deformation resistance of the hot-rolled steel strip that is the raw material is large, and the sheet thickness is reduced to a lower level than before. Therefore, the cold rolling load increases. As a result, the cold tandem rolling mill needs to be passed through multiple times to increase the number of cold rolling passes, and troubles such as breakage are likely to occur during rolling. There is a problem that the operating rate is lowered, and the productivity of the high-strength steel sheet is lowered. Further, since the deformation resistance of the hot-rolled steel strip is large, there is a problem that the shape of the high-strength steel plate obtained by cold rolling is deteriorated and the yield is reduced.

このような問題を解消するために、冷間圧延を施す前の熱延鋼帯に熱処理を施して軟質化することによって、その熱延鋼帯の変形抵抗を低減する技術が検討されている。   In order to solve such a problem, a technique for reducing the deformation resistance of the hot-rolled steel strip by subjecting the hot-rolled steel strip before cold rolling to heat treatment to soften it has been studied.

たとえば特許文献1には、冷間圧延に先立って、BAF焼鈍炉あるいは連続焼鈍炉を用いて焼戻し処理を施して、熱延鋼帯を均一に軟質化する技術が開示されている。その焼戻し処理における焼戻し温度と焼戻し時間は、熱間圧延の終了した熱延鋼帯をコイル(以下、熱延コイルという)に巻取る際の温度に応じて調整されるが、BAF焼鈍炉や連続焼鈍炉を使用するので、以下のような種々の問題が発生する。   For example, Patent Document 1 discloses a technique for performing a tempering process using a BAF annealing furnace or a continuous annealing furnace prior to cold rolling to uniformly soften the hot-rolled steel strip. The tempering temperature and tempering time in the tempering process are adjusted according to the temperature when the hot-rolled steel strip after hot rolling is wound on a coil (hereinafter referred to as hot-rolled coil). Since an annealing furnace is used, the following various problems occur.

BAF焼鈍炉による焼戻し処理は、熱延コイルを個別に収納してバッチ処理で焼戻しを行なうものであり、熱延コイル全体を加熱−均熱−徐冷する一連の工程に多大な時間を要するので、焼戻しの能率向上は期待できない。多数のBAF焼鈍炉を設置して、同時に複数の熱延コイルに焼戻しを施すことによって、能率を高めることは可能であるが、大幅な能率向上は困難であり、しかも、立地条件の制約を受ける工場では、BAF焼鈍炉の増設は極めて難しい。   The tempering process by the BAF annealing furnace is a process in which the hot-rolled coils are individually stored and tempered by batch processing, and it takes a lot of time for a series of processes of heating-soaking-slow cooling the entire hot-rolling coil. The improvement in tempering efficiency cannot be expected. It is possible to increase the efficiency by installing a large number of BAF annealing furnaces and simultaneously tempering a plurality of hot-rolled coils, but it is difficult to significantly improve the efficiency, and there are restrictions on site conditions. In factories, it is extremely difficult to add a BAF annealing furnace.

また、大型の容器(以下、ベルという)に複数の熱延コイルを収納してBAF焼鈍炉に装入すれば、焼戻しの能率を高めることは可能である。しかし、熱延コイルに巻取られた熱延鋼帯の成分が異なる場合に、それぞれの成分に応じて焼戻し温度や焼戻し時間を調整する必要があるので、ベルの収納量を常に満たして操業するのは難しい。つまりベルを使用しても、大幅な能率向上は困難である。   Further, if a plurality of hot-rolled coils are housed in a large container (hereinafter referred to as a bell) and placed in a BAF annealing furnace, the tempering efficiency can be increased. However, when the components of the hot-rolled steel strip wound around the hot-rolled coil are different, it is necessary to adjust the tempering temperature and tempering time according to the respective components, so that the bell storage capacity is always satisfied. Is difficult. In other words, even if a bell is used, it is difficult to significantly improve efficiency.

さらに、BAF焼鈍炉によるバッチ処理では焼戻しに長時間を要するので、成分によっては熱延鋼帯が脆化する惧れがある。その結果、冷間圧延において破断が発生し、冷間圧延設備の稼動率の低下および高強度鋼板の歩留りの低下を招くという問題も生じる。   Furthermore, since batch processing using a BAF annealing furnace requires a long time for tempering, the hot-rolled steel strip may become brittle depending on the components. As a result, breakage occurs in the cold rolling, causing a problem that the operating rate of the cold rolling equipment is lowered and the yield of the high-strength steel sheet is lowered.

連続焼鈍炉を用いると、過時効帯の領域で焼戻しを行なうことが可能であり、能率向上を図ることができる。しかし焼戻し時間は、過時効帯の長さと熱延鋼帯の通板速度との関係で決定される値であり、通常の通板速度では最大3分程度となる。つまり連続焼鈍炉では、3分程度の短い焼戻し時間しか得られないので、十分な軟質化が図れない。また、Mn含有量の大きい熱延鋼帯では、Mnがオーステナイト中に濃化するのに要する時間を確保できないので、高強度鋼板の機械的特性が劣化するという問題もある。   When a continuous annealing furnace is used, tempering can be performed in the region of an overaging zone, and efficiency can be improved. However, the tempering time is a value determined by the relationship between the length of the overaged zone and the sheeting speed of the hot-rolled steel band, and is a maximum of about 3 minutes at the normal sheeting speed. That is, in a continuous annealing furnace, only a short tempering time of about 3 minutes can be obtained, so that sufficient softening cannot be achieved. In addition, in a hot-rolled steel strip having a large Mn content, the time required for Mn to concentrate in austenite cannot be secured, and there is also a problem that the mechanical properties of the high-strength steel plate deteriorate.

特開2010-144243号公報JP 2010-144243 A

本発明は、従来の技術の問題点を解消し、熱間圧延から冷間圧延を経て高強度鋼板を製造する過程で、冷間圧延に先立って熱延鋼帯を軟質化するための熱処理を行なうにあたって、適正な熱処理時間を確保することによって均一かつ十分な軟質化を可能とし、しかも熱処理能率の向上も可能とする熱処理設備を提供することを目的とする。   The present invention eliminates the problems of the prior art, and in the process of manufacturing a high-strength steel sheet from hot rolling to cold rolling, a heat treatment for softening the hot-rolled steel strip prior to cold rolling. An object of the present invention is to provide a heat treatment facility that can ensure uniform and sufficient softening by ensuring an appropriate heat treatment time, and can also improve heat treatment efficiency.

本発明者は、高強度鋼板を製造する際の冷間圧延の負荷を軽減するために、熱延鋼帯を軟質化するための熱処理を施す技術について検討し、熱延鋼帯を熱処理設備に連続的に供給することによって、軟質化に要する時間を短縮でき、ひいては高強度鋼板の生産性を向上できる点に着目した。ところが、熱処理の所要時間を短縮すれば、軟質化が不均一に生じるという問題がある。そこで、熱処理時間の短縮と均一な軟質化とを両立できる技術について詳細に研究した。   In order to reduce the cold rolling load when manufacturing a high-strength steel sheet, the present inventor has studied a technique for performing a heat treatment for softening the hot-rolled steel strip, and uses the hot-rolled steel strip as a heat treatment facility. We focused on the fact that the time required for softening can be shortened by continuous supply, and as a result, the productivity of high-strength steel sheets can be improved. However, if the time required for the heat treatment is shortened, there is a problem that softening occurs unevenly. Therefore, we studied in detail the technology that can achieve both shortening of heat treatment time and uniform softening.

その結果、加熱した熱延鋼帯をコイル(以下、熱処理コイルという)に巻取り、その熱処理コイルを好適な温度範囲に保持することによって、熱延鋼帯の全長および全幅にわたって(すなわち熱処理コイルの中央部まで)均一に軟質化できるという知見を得た。   As a result, the heated hot-rolled steel strip is wound on a coil (hereinafter referred to as a heat-treated coil), and the heat-treated coil is maintained in a suitable temperature range, so that the entire length and width of the hot-rolled steel strip (ie, the heat-treated coil) The knowledge that it can be softened uniformly was obtained.

そして、その軟質化した熱延鋼帯を冷間圧延することによって、良好な形状の高強度鋼板の形状を得ることができ、ひいては歩留り向上を図ること可能となる。   Then, by cold rolling the softened hot-rolled steel strip, it is possible to obtain a shape of a high-strength steel plate having a favorable shape, thereby improving the yield.

本発明は、このような知見に基づいてなされたものである。   The present invention has been made based on such knowledge.

すなわち本発明は、熱延鋼帯に熱処理を施す熱処理設備であって、熱延鋼帯を巻取った熱延コイルから熱延鋼帯を巻戻して連続的に供給する巻戻し手段と、巻戻し手段から供給される熱延鋼帯を不活性ガス雰囲気内で500℃以上に加熱する鋼帯加熱手段と、該鋼帯加熱手段の出側で該鋼帯加熱手段における加熱温度と熱処理コイルとして巻取るときの巻取り温度との差を100℃以内として前記熱延鋼帯を前記熱処理コイルとして巻取る巻取り手段と、前記鋼帯加熱手段の出側から前記巻取り手段に至る搬送経路の一部または全部をカバーし、その内部を不活性ガス雰囲気とする前記搬送経路と、前記巻取り手段から前記熱処理コイルを搬出するコイル搬送台車、クレーンまたはフォークリフトである搬送手段と、該搬送手段で搬送された前記熱処理コイルを不活性ガス雰囲気内で所定の時間にわたって保熱する保熱手段と、を有する熱延鋼帯の熱処理設備である。 That is, the present invention is a heat treatment facility for performing a heat treatment on a hot-rolled steel strip, a rewinding means for continuously rewinding the hot-rolled steel strip from a hot-rolled coil wound with the hot-rolled steel strip, Steel strip heating means for heating the hot-rolled steel strip supplied from the return means to 500 ° C. or more in an inert gas atmosphere, and the heating temperature and heat treatment coil in the steel strip heating means on the outlet side of the steel strip heating means Winding means for winding the hot-rolled steel strip as the heat treatment coil with a difference from the winding temperature when winding within 100 ° C., and a conveying path from the exit side of the steel strip heating means to the winding means A part of or the whole of the transport path , the interior of which is an inert gas atmosphere; The heat treatment carried And the coercive heat heat retaining means for a predetermined time the coil in an inert gas atmosphere, a heat treatment equipment of hot rolled strip having a.

本発明の熱処理設備においては、鋼帯加熱手段が誘導加熱で熱延鋼帯を昇温することが好ましい。また、保熱手段が熱処理コイルを覆う保熱カバーを有し、保熱カバーがその内部温度を500℃以上に維持する補助加熱手段を有することが好ましい。   In the heat treatment equipment of the present invention, it is preferable that the steel strip heating means raise the temperature of the hot-rolled steel strip by induction heating. Moreover, it is preferable that the heat retaining means has a heat retaining cover for covering the heat treatment coil, and the heat retaining cover has auxiliary heating means for maintaining the internal temperature at 500 ° C. or higher.

本発明によれば、熱間圧延から冷間圧延を経て高強度鋼板を製造する過程で、冷間圧延に先立って熱延鋼帯を軟質化するための熱処理を行なうにあたって、適正な熱処理時間を確保することによって均一かつ十分な軟質化が可能となり、しかも熱処理能率の向上も可能となるので、産業上格段の効果を奏する。   According to the present invention, in the process of manufacturing a high-strength steel sheet from hot rolling to cold rolling, an appropriate heat treatment time is set for performing heat treatment for softening the hot-rolled steel strip prior to cold rolling. By ensuring, uniform and sufficient softening can be achieved, and further, the heat treatment efficiency can be improved, so that it has a remarkable industrial effect.

本発明の熱処理設備の例を模式的に示す説明図であり、(a)は巻戻し手段、鋼帯加熱手段、巻取り手段の配置、(b)は搬送手段、(c)は保熱手段を示す。It is an explanatory view schematically showing an example of the heat treatment equipment of the present invention, (a) is an unwinding means, steel strip heating means, arrangement of winding means, (b) is a conveying means, (c) is a heat retaining means. Indicates. 熱処理コイルの例を模式的に示す断面図である。It is sectional drawing which shows the example of the heat processing coil typically. 保熱手段の他の例を模式的に示す説明図である。It is explanatory drawing which shows the other example of a heat retention means typically. 鋼帯加熱手段の他の例を模式的に示す説明図である。It is explanatory drawing which shows the other example of a steel strip heating means typically.

本発明の熱処理設備は、高強度鋼板の素材となる熱延鋼帯を軟質化するものであり、とりわけ、熱間圧延の出側で熱延鋼帯を巻取った熱延コイルの冷却過程で200℃以下まで温度が低下して、硬質な低温変態相(たとえばベイナイトやマルテンサイト等)が生成し、冷間圧延における変形抵抗が著しく大きくなって、所定の板厚に圧下するのが困難な熱延鋼帯の軟質化に有効である。   The heat treatment equipment of the present invention softens the hot-rolled steel strip that is the material of the high-strength steel sheet, and in particular, in the cooling process of the hot-rolled coil that has been wound up on the outlet side of hot rolling. The temperature is lowered to 200 ° C or lower, and a hard low-temperature transformation phase (for example, bainite, martensite, etc.) is generated. Deformation resistance in cold rolling is remarkably increased, and it is difficult to reduce to a predetermined sheet thickness. Effective for softening hot-rolled steel strip.

熱処理設備に供給される熱延コイルは、
(1)熱間圧延が終了した熱延鋼帯を巻取った熱延コイル、
あるいは
(2)熱間圧延が終了した後、さらに酸洗を施した熱延鋼帯を巻取った熱延コイル
である。なお、上記(1)の熱延コイルを熱処理設備に供給する場合は、熱処理(すなわち昇温および保熱)が終了した熱延鋼帯を熱処理コイルに巻取り、その熱処理コイルに酸洗を施した後に、冷間圧延に供することが好ましい。上記(2)の熱延コイルを熱処理設備に供給する場合は、熱処理(すなわち昇温および保熱)が終了した熱延鋼帯を熱処理コイルに巻取って、冷間圧延に供することが好ましい。
The hot rolled coil supplied to the heat treatment equipment
(1) A hot-rolled coil wound with a hot-rolled steel strip that has been hot-rolled,
Or
(2) A hot-rolled coil obtained by winding a hot-rolled steel strip that has been pickled after hot rolling. When supplying the hot-rolled coil (1) to the heat treatment equipment, the hot-rolled steel strip that has been heat-treated (that is, raising the temperature and keeping the heat) is wound on the heat-treated coil, and the heat-treated coil is pickled. Then, it is preferable to use for cold rolling. When supplying the hot-rolled coil of (2) above to the heat treatment facility, it is preferable to wind the hot-rolled steel strip after the heat treatment (that is, raising the temperature and keeping the heat) around the heat-treated coil and subjecting it to cold rolling.

また、いずれの熱処理コイルも、巻替え等の所定の工程を経て冷間圧延に供給しても良い。   Further, any heat treatment coil may be supplied to cold rolling through a predetermined process such as rewinding.

冷間圧延で得られた高強度鋼板に焼鈍を施して、所望の機械的特性を得る場合には、本発明の熱処理設備を用いて焼鈍を行なうこともできる。従来の高強度鋼板の製造技術では、連続焼鈍炉やバッチ焼鈍炉を使用しているが、本発明の熱処理設備を使用すれば、機械的特性を調整する効果が従来の焼鈍炉と同様に得られる。   When the high strength steel plate obtained by cold rolling is annealed to obtain desired mechanical properties, it can be annealed using the heat treatment equipment of the present invention. In conventional high-strength steel sheet manufacturing technology, continuous annealing furnaces and batch annealing furnaces are used, but if the heat treatment equipment of the present invention is used, the effect of adjusting the mechanical properties can be obtained in the same way as with conventional annealing furnaces. It is done.

熱処理設備の鋼帯加熱手段は、熱延鋼帯を所定の温度まで昇温するものであり、その温度に保持する機能は備えていない。加熱された熱延鋼帯を一定の温度に保持する機能は、保熱手段が担う。保熱手段にて温度低下を抑制しながら保持される時間(以下、保熱時間という)は、熱延鋼帯の成分や温度履歴、高強度鋼板の用途等に応じて適宜設定し、数分程度から数日程度まで広い範囲に適用できる。ただし、保熱時間が10分未満の短時間で軟質化を達成できる熱延鋼帯は、従来の熱処理炉(たとえば連続焼鈍炉等)を用いて同様の効果が得られるので、本発明の熱処理設備を使用する意味がない。一方で、保熱時間が10時間(=600分)を超える長時間を要する熱延鋼帯も、従来の熱処理炉(たとえばBAF焼鈍炉等)を用いて同様の効果が得られるので、本発明の熱処理設備を使用する意味がない。したがって本発明の熱処理設備は、保熱時間が10〜600分の範囲内で軟質化を図る熱延鋼帯に用いるのが好ましい。   The steel strip heating means of the heat treatment equipment raises the temperature of the hot-rolled steel strip to a predetermined temperature, and does not have a function of maintaining that temperature. The heat retaining means bears the function of maintaining the heated hot-rolled steel strip at a constant temperature. The time kept while suppressing the temperature drop by the heat retaining means (hereinafter referred to as the heat retaining time) is appropriately set according to the composition of the hot rolled steel strip, the temperature history, the use of the high strength steel sheet, etc., and is several minutes. Applicable to a wide range from about to several days. However, since a hot-rolled steel strip that can achieve softening in a short time with a heat retention time of less than 10 minutes can obtain the same effect using a conventional heat treatment furnace (for example, a continuous annealing furnace), the heat treatment of the present invention There is no point in using the equipment. On the other hand, a hot-rolled steel strip that requires a long heat retention time exceeding 10 hours (= 600 minutes) can obtain the same effect using a conventional heat treatment furnace (for example, a BAF annealing furnace). There is no point in using the heat treatment equipment. Therefore, the heat treatment equipment of the present invention is preferably used for a hot-rolled steel strip that is softened within a heat retention time of 10 to 600 minutes.

以下に、図を参照して、本発明の熱処理設備について説明する。   The heat treatment equipment of the present invention will be described below with reference to the drawings.

図1は、本発明の熱処理設備の例を模式的に示す説明図であり、(a)は巻戻し手段、鋼帯加熱手段、巻取り手段の配置、(b)は搬送手段、(c)は保熱手段を示す。図1中の矢印Aは、熱延鋼帯1の進行方向を示す。   FIG. 1 is an explanatory view schematically showing an example of the heat treatment facility of the present invention, in which (a) is an arrangement of rewinding means, steel strip heating means, and winding means, (b) is conveying means, (c) Indicates a heat retaining means. An arrow A in FIG. 1 indicates the traveling direction of the hot-rolled steel strip 1.

図1(a)に示すように、熱延コイル2を巻戻し手段3に装填し、熱延コイル2から熱延鋼帯1を巻戻しながら連続的に鋼帯加熱手段4に供給する。鋼帯加熱手段4の入側と出側にブライドルロール5を配設して、熱延鋼帯1に張力を付与しながら、加熱することが好ましい。その理由は、熱延鋼帯1を安定して搬送することによって、形状不良の発生や寸法精度の劣化を防止できるからである。図1にはブライドルロール5を配設する例を示したが、一対のロールで熱延鋼帯1を挟持するピンチロールを用いても、同様の効果が得られる。また、複数のローラーで構成される搬送テーブル(いわゆるローラーコンベア)のように、複数のローラーを回転させることで、熱延鋼帯1の自重に応じた摩擦力を発生させ、その摩擦力を利用して搬送する方式を採用しても良い。   As shown in FIG. 1 (a), the hot-rolled coil 2 is loaded into the rewinding means 3, and the hot-rolled steel strip 1 is continuously fed from the hot-rolled coil 2 to the steel strip heating means 4. It is preferable to dispose bridle rolls 5 on the entry side and the exit side of the steel strip heating means 4 and heat the hot-rolled steel strip 1 while applying tension. The reason is that occurrence of shape defects and deterioration of dimensional accuracy can be prevented by stably transporting the hot-rolled steel strip 1. Although the example which arrange | positions the bridle roll 5 was shown in FIG. 1, the same effect is acquired even if it uses the pinch roll which clamps the hot-rolled steel strip 1 with a pair of roll. Moreover, the friction force according to the dead weight of the hot-rolled steel strip 1 is generated by rotating a plurality of rollers like a transport table (so-called roller conveyor) composed of a plurality of rollers, and the friction force is used. In this case, a method for conveying the sheet may be adopted.

鋼帯加熱手段4における熱延鋼帯1の加熱温度が500℃未満では、熱延鋼帯1を軟質化する効果が得られない。したがって、加熱温度は500℃以上とする。ただし、加熱温度が750℃を超えると、エネルギー消費量の増加(すなわち操業コストの増加)を招くばかりでなく、熱延鋼帯1幅方向のネッキングが発生して安定した搬送が困難になり、その結果、形状不良の発生や寸法精度の劣化の原因になる。また、加熱温度が高すぎる場合には、後述する保熱手段の出側の冷却過程で、マルテンサイトやベイナイト等の硬質な低温変態相が多く生成し、熱延鋼帯1の軟質化が困難になる。したがって、鋼帯加熱手段4における熱延鋼帯1の加熱温度は500〜750℃の範囲内が好ましい。   If the heating temperature of the hot-rolled steel strip 1 in the steel strip heating means 4 is less than 500 ° C., the effect of softening the hot-rolled steel strip 1 cannot be obtained. Therefore, the heating temperature is 500 ° C. or higher. However, when the heating temperature exceeds 750 ° C., not only increases in energy consumption (that is, increases in operating cost), but also necking in the width direction of the hot-rolled steel strip occurs, making stable conveyance difficult. As a result, shape defects occur and dimensional accuracy deteriorates. If the heating temperature is too high, a lot of hard low-temperature transformation phases such as martensite and bainite are generated in the cooling process on the exit side of the heat retaining means described later, and it is difficult to soften the hot-rolled steel strip 1. become. Therefore, the heating temperature of the hot-rolled steel strip 1 in the steel strip heating means 4 is preferably in the range of 500 to 750 ° C.

鋼帯加熱手段4の構成は特に限定せず、広く普及している加熱炉(たとえば連続焼鈍炉等)を使用することができる。燃料の燃焼熱で加熱する加熱炉(たとえば直火型無酸化方式や輻射管加熱方式等)を保有する場合は、その既存の設備を用いて熱延鋼帯1を加熱すれば良い。ただし、鋼帯加熱手段4を小型化して、熱処理設備の関連機器の配置を簡素化する観点から、電気加熱方式(すなわち通電加熱方式または誘導加熱方式)の加熱装置を採用することが好ましい。電気加熱方式を採用すれば、熱延鋼帯1表面の酸化を抑制する効果も得られる。   The structure of the steel strip heating means 4 is not particularly limited, and a widely used heating furnace (for example, a continuous annealing furnace) can be used. When a heating furnace (for example, a direct flame type non-oxidation system or a radiant tube heating system) that heats with the combustion heat of the fuel is possessed, the hot-rolled steel strip 1 may be heated using the existing equipment. However, from the viewpoint of downsizing the steel strip heating means 4 and simplifying the arrangement of the related equipment of the heat treatment equipment, it is preferable to employ a heating device of an electric heating method (that is, an electric heating method or an induction heating method). If an electric heating system is employ | adopted, the effect which suppresses the oxidation of the hot rolled steel strip 1 surface will also be acquired.

通電加熱方式は、熱延鋼帯1に電流を直接流すので、鋼帯加熱手段4の小型化のみならず加熱時間の短縮に有利である。しかし、熱延鋼帯1の温度のばらつきが生じ易いという欠点がある。   The electric heating method is advantageous not only for reducing the size of the steel strip heating means 4 but also for shortening the heating time because the current flows directly through the hot-rolled steel strip 1. However, there is a drawback that the temperature of the hot-rolled steel strip 1 tends to vary.

誘導加熱方式は、熱延鋼帯1を短時間で加熱でき、しかも温度を容易に制御することが可能である。したがって、熱延鋼帯1を短時間で均一に加熱するためには、誘導加熱方式の鋼帯加熱手段4を用いることが好ましい。形状不良(たとえば波うち等)が生じた熱延鋼帯1を加熱する際に、誘導加熱方式を採用することによって、鋼帯加熱手段4を安定して操業できるという効果も得られる。   In the induction heating method, the hot-rolled steel strip 1 can be heated in a short time, and the temperature can be easily controlled. Therefore, in order to heat the hot-rolled steel strip 1 uniformly in a short time, it is preferable to use an induction heating type steel strip heating means 4. When the hot-rolled steel strip 1 having a defective shape (for example, a wave) is heated, an effect that the steel strip heating means 4 can be stably operated can be obtained by adopting an induction heating method.

熱延鋼帯1を鋼帯加熱手段4で加熱した後、熱処理コイル6として巻取り手段7で巻取る。図1(a)には、鋼帯加熱手段4と巻取り手段7との間に、上記のブライドルロール5を配設する例を示したが、さらに熱延鋼帯1を加熱または保熱するための温度調整手段を配設しても良い。温度調整手段を配設することによって、熱処理コイル6として巻取り手段7で巻取るときの熱延鋼帯1の温度(いわゆる巻取り温度)を調整することが可能となる。   After the hot-rolled steel strip 1 is heated by the steel strip heating means 4, it is wound up by the winding means 7 as a heat treatment coil 6. FIG. 1 (a) shows an example in which the bridle roll 5 is disposed between the steel strip heating means 4 and the winding means 7, but the hot-rolled steel strip 1 is further heated or heat-retained. A temperature adjusting means may be provided. By disposing the temperature adjusting means, it is possible to adjust the temperature of the hot-rolled steel strip 1 (so-called winding temperature) when the heat treatment coil 6 is wound by the winding means 7.

鋼帯加熱手段4における加熱温度と、熱処理コイル6として巻取るときの巻取り温度との差(以下、鋼帯温度差という)は100℃以内が好ましい。つまり熱処理コイル6に巻取ることによって、熱延鋼帯1の冷却速度が小さくなるので、鋼帯温度差を100℃以内として比較的高温の熱延鋼帯1を巻取って、熱処理コイル6が室温まで冷却される所要時間を長くする。   The difference between the heating temperature in the steel strip heating means 4 and the winding temperature when winding as the heat treatment coil 6 (hereinafter referred to as the steel strip temperature difference) is preferably within 100 ° C. That is, since the cooling rate of the hot-rolled steel strip 1 is reduced by winding it on the heat-treated coil 6, the heat-treated coil 6 is wound by winding the relatively hot hot-rolled steel strip 1 with the steel strip temperature difference within 100 ° C. Increase the time required for cooling to room temperature.

通常の熱処理設備の設備配列では、鋼帯温度差を100℃以内に抑えられるので、熱延鋼帯1を支障なく軟質化できる。したがって、温度調整手段を使用する必要はない。   In the equipment arrangement of the normal heat treatment equipment, the steel strip temperature difference can be suppressed within 100 ° C., so that the hot-rolled steel strip 1 can be softened without any trouble. Therefore, it is not necessary to use temperature adjusting means.

熱延鋼帯1の搬送速度が小さい場合、あるいは鋼帯加熱手段4と巻取り手段7との距離が遠い場合は、鋼帯温度差が100℃を超える惧れがある。そこで、たとえば、
(A)鋼帯加熱手段4出側から巻取り手段7に至る搬送経路の一部または全部をカバー(以下、緩冷却カバーという)で覆う、
(B)鋼帯加熱手段4と巻取り手段7の間に加熱炉を設置する
等の温度調整手段を設けて、鋼帯加熱手段4出側から巻取り手段7に至る搬送経路における鋼帯温度差を、100℃以内に抑制することが可能となる。
When the conveying speed of the hot-rolled steel strip 1 is low, or when the distance between the steel strip heating means 4 and the winding means 7 is long, the steel strip temperature difference may exceed 100 ° C. So, for example,
(A) Covering part or all of the transport path from the steel strip heating means 4 exit side to the winding means 7 with a cover (hereinafter referred to as a slow cooling cover);
(B) The temperature of the steel strip in the conveying path from the steel strip heating means 4 to the winding means 7 by providing a temperature adjusting means such as installing a heating furnace between the steel strip heating means 4 and the winding means 7 The difference can be suppressed within 100 ° C.

加熱炉(たとえばトンネル炉等)の加熱方式は、特に限定しないが、熱延鋼帯1表面の酸化を抑制する観点から電気ヒーターが好ましい。さらに、加熱炉や緩冷却カバーの内部を不活性ガス雰囲気とすることによって、酸化を抑制する効果が一層向上する。このようにして熱延鋼帯1表面の酸化を抑制することによって、後述する冷間圧延工程で得られる高強度鋼板に化成処理や溶融亜鉛めっき処理を施す際に、良好な化成皮膜やメッキ皮膜を形成することができる。   The heating method of the heating furnace (for example, a tunnel furnace) is not particularly limited, but an electric heater is preferable from the viewpoint of suppressing oxidation of the surface of the hot-rolled steel strip 1. Furthermore, the effect of suppressing oxidation is further improved by making the inside of the heating furnace and the slow cooling cover an inert gas atmosphere. By suppressing oxidation of the surface of the hot-rolled steel strip 1 in this way, a good chemical conversion film or plating film can be obtained when performing chemical conversion treatment or hot dip galvanizing treatment on a high-strength steel plate obtained in the cold rolling process described later. Can be formed.

巻取り手段7は、高温の熱延鋼帯1を巻取ることが可能なものを使用する。熱延鋼帯1を熱処理コイル6として巻取ることによって、その後の温度低下を抑制できるので、熱処理コイル6の加熱を行なわずに、長時間に温度を保持することが可能である。   As the winding means 7, one capable of winding the high-temperature hot-rolled steel strip 1 is used. By winding the hot-rolled steel strip 1 as the heat treatment coil 6, it is possible to suppress a subsequent temperature drop, so that the temperature can be maintained for a long time without heating the heat treatment coil 6.

巻取り手段7は、通常の熱処理設備で使用されるものを使用しても良いが、熱処理コイル6内周部に加熱スリーブや断熱スリーブを装着することが可能なものが好ましい。その加熱スリーブや断熱スリーブについて、図2に示す断面図を参照して、以下に説明する。   Although the winding means 7 may use what is used with normal heat processing equipment, what can equip the inner peripheral part of the heat processing coil 6 with a heating sleeve and a heat insulation sleeve is preferable. The heating sleeve and the heat insulating sleeve will be described below with reference to the cross-sectional view shown in FIG.

図2に示すように、熱処理コイル6内周部と接触する部位に加熱スリーブ8を装着することが好ましい。熱処理コイル6内周部は、巻取り手段7のマドレルと接触して冷却速度が増加し易いので、ヒーター(たとえば電気ヒーター等)を内蔵した加熱スリーブ8を装着することによって、熱処理コイル6内周部の温度低下を抑制することが可能となる。したがって、加熱スリーブ8を熱延鋼帯1の温度(500℃以上)と同程度まで昇温する必要はなく、熱処理コイル6内周部の温度低下を抑える程度に昇温すれば良い。   As shown in FIG. 2, it is preferable to attach the heating sleeve 8 to the site | part which contacts the heat treatment coil 6 inner peripheral part. Since the inner peripheral portion of the heat treatment coil 6 is in contact with the mandrel of the winding means 7 and the cooling rate is likely to increase, the inner periphery of the heat treatment coil 6 can be obtained by mounting the heating sleeve 8 incorporating a heater (for example, an electric heater). It is possible to suppress the temperature drop of the part. Therefore, it is not necessary to raise the temperature of the heating sleeve 8 to the same level as the temperature of the hot-rolled steel strip 1 (500 ° C. or higher), and it is sufficient to raise the temperature to such an extent that the temperature decrease of the inner peripheral portion of the heat treatment coil 6 is suppressed.

加熱スリーブ8の内側(すなわち巻取り手段7マドレルに接触する側)には、断熱スリーブ9を装着することが好ましい。断熱スリーブ9を装着することによって、加熱スリーブ8から巻取り手段7のマドレルへの熱伝導を抑制することが可能となり、その結果、巻取り手段7の温度上昇を防止して、巻取り手段7を保護することができる。   It is preferable to install a heat insulating sleeve 9 on the inner side of the heating sleeve 8 (that is, the side in contact with the winding means 7 madrel). By mounting the heat insulating sleeve 9, it becomes possible to suppress the heat conduction from the heating sleeve 8 to the mandrel of the winding means 7, and as a result, the temperature rise of the winding means 7 is prevented and the winding means 7 is prevented. Can be protected.

ただし加熱スリーブ8は、ヒーターから発生する熱で膨張する。加熱スリーブ8の膨張に起因して、加熱スリーブ8と断熱スリーブ9との間、あるいは断熱スリーブ9と巻取り手段7マドレルとの間に隙間が生じると、巻取り手段7マドレルの空転や巻取り力の低下を引き起こす。したがって、熱処理コイル6、加熱スリーブ8、断熱スリーブ9、巻取り手段7マドレルは、それぞれ密着させることが好ましい。   However, the heating sleeve 8 expands with heat generated from the heater. If a gap is generated between the heating sleeve 8 and the heat insulating sleeve 9 or between the heat insulating sleeve 9 and the winding means 7 madrel due to the expansion of the heating sleeve 8, the winding means 7 is idled or wound. Causes power loss. Therefore, it is preferable that the heat treatment coil 6, the heating sleeve 8, the heat insulating sleeve 9, and the winding means 7 are made in close contact with each other.

このようにして熱延鋼帯1を熱処理コイル6として巻取った後に、搬送手段を用いて巻取り手段7から搬出し、さらに保熱手段に搬送する。   After the hot-rolled steel strip 1 is wound up as the heat treatment coil 6 in this way, it is unloaded from the winding means 7 using the conveying means and further conveyed to the heat retaining means.

図1(b)は、搬送手段の例を模式的に示す説明図である。搬送手段10は、巻取り手段7から熱処理コイル6を搬出する機能と、後述する保熱手段に搬送する機能を有するものであり、通常の熱処理設備で使用するコイル搬送台車を使用すれば良い。ただし、搬送手段10の上面、特に熱処理コイル6と接触する部位を断熱構造として、熱処理コイル6の温度低下を抑制することが好ましい。さらに、搬送手段10に載置した熱処理コイル6を断熱材等で覆うことによって、熱処理コイル6の温度低下を抑制する効果が一層向上する。   FIG. 1B is an explanatory diagram schematically showing an example of the conveying means. The conveying means 10 has a function of carrying out the heat treatment coil 6 from the winding means 7 and a function of conveying it to a heat retaining means described later, and a coil conveying carriage used in normal heat treatment equipment may be used. However, it is preferable to suppress the temperature drop of the heat treatment coil 6 by making the upper surface of the transport means 10, particularly the portion that contacts the heat treatment coil 6, into a heat insulating structure. Furthermore, the effect of suppressing the temperature drop of the heat treatment coil 6 is further improved by covering the heat treatment coil 6 placed on the conveying means 10 with a heat insulating material or the like.

巻取り手段7から保熱手段までの距離が近い場合(すなわち搬送時間が短い場合)は、搬送手段として、図1(b)に示すような台車に替えて、クレーンやフォークリフト等の重量物の搬送が可能な運搬用機材を使用しても良い。それらの運搬用機材を用いて搬送する場合は断熱性を高めることが困難であるが、短時間の搬送であれば、熱処理コイル6の温度低下を抑えることができる。   When the distance from the winding means 7 to the heat retaining means is short (that is, when the transport time is short), instead of the cart as shown in FIG. Transportation equipment that can be transported may be used. Although it is difficult to improve the heat insulating property when transporting using such transporting equipment, a decrease in temperature of the heat treatment coil 6 can be suppressed if transporting for a short time.

次に、熱処理コイル6は、保熱手段にて所定の時間にわたって保熱される。   Next, the heat treatment coil 6 is heated for a predetermined time by the heat holding means.

図1(c)は、保熱手段の例を模式的に示す説明図である。   FIG.1 (c) is explanatory drawing which shows the example of a heat retention means typically.

保熱手段は、熱処理コイル6をカバー11(以下、保熱カバーという)に収納して、温度低下を抑制しながら保持する。保熱カバー11に収納することによって、熱エネルギーの放散を防止できるので、保熱カバー11に補助的な加熱手段12(以下、補助加熱手段といいう)を設けなくても、熱処理コイル6を高温(500℃以上)に保持することが可能となる。   The heat retaining means accommodates the heat treatment coil 6 in a cover 11 (hereinafter referred to as a heat retaining cover) and holds it while suppressing a temperature drop. Since heat dissipation can be prevented by storing in the heat insulating cover 11, the heat treatment coil 6 can be heated at a high temperature without providing auxiliary heat means 12 (hereinafter referred to as auxiliary heating means) in the heat insulating cover 11. (500 ° C. or higher) can be maintained.

ただし、熱処理コイル6を500℃以上に長時間保持する必要がある場合は、保熱カバー11に補助加熱手段12を設けても良い。   However, if it is necessary to hold the heat treatment coil 6 at 500 ° C. or higher for a long time, the auxiliary heating means 12 may be provided in the heat insulating cover 11.

この保熱手段(たとえば保熱カバー11等)を、上記の鋼帯加熱手段4とは別に設ける理由は、巻取り手段7を断熱材で覆って、熱処理コイル6の温度保持を行なうと、鋼帯加熱手段4の生産性低下を招くからである。   The reason why this heat retaining means (for example, the heat retaining cover 11) is provided separately from the steel strip heating means 4 is that when the temperature of the heat treatment coil 6 is maintained by covering the winding means 7 with a heat insulating material, the steel This is because the productivity of the belt heating means 4 is reduced.

保熱カバー11は、その内部を不活性ガス雰囲気として、熱延鋼帯1表面の酸化を抑制することが好ましく、その雰囲気を維持するために、雰囲気制御装置13を備えることが好ましい。   The heat insulating cover 11 preferably has an inert gas atmosphere inside to suppress oxidation of the surface of the hot-rolled steel strip 1 and preferably includes an atmosphere control device 13 in order to maintain the atmosphere.

なお図1(c)には、熱処理コイル6を1個ずつ保熱カバー11に収納する例を示したが、複数個の熱処理コイル6をピット14に収納し、開口部を保熱カバー11で覆うような構成(図3参照)であっても、同様の効果が得られる。   FIG. 1 (c) shows an example in which the heat treatment coils 6 are housed one by one in the heat insulating cover 11, but a plurality of heat treatment coils 6 are housed in the pits 14 and the openings are covered by the heat retaining cover 11. Even if it is the structure which covers (refer FIG. 3), the same effect is acquired.

このようにして保熱手段にて所定の時間にわたって保熱した後、保熱カバー11を撤去して空冷を促進して、熱処理コイル6を冷間圧延に送給する。所定の保熱時間が経過した熱処理コイル6を、一旦コイルヤードに保管し、その後、冷間圧延に送給しても良い。   Thus, after heat-retaining means for a predetermined time, the heat-retaining cover 11 is removed to promote air cooling, and the heat treatment coil 6 is fed to cold rolling. The heat treatment coil 6 that has passed a predetermined heat retention time may be temporarily stored in a coil yard and then fed to cold rolling.

あるいは、積極的に冷却媒体(たとえば液体、気体等)を熱延鋼帯1に吹付けて強制冷却を行ない、その後、冷間圧延に送給しても良い。その理由は、熱延鋼帯1を、保熱手段から短時間で冷間圧延へ送給でき、高強度鋼板の生産性向上に寄与するからである。   Alternatively, the cooling medium (for example, liquid, gas, etc.) may be positively sprayed on the hot-rolled steel strip 1 to perform forced cooling, and then fed to cold rolling. The reason is that the hot-rolled steel strip 1 can be fed from the heat retaining means to the cold rolling in a short time and contributes to the improvement of the productivity of the high-strength steel plate.

また、保熱の後に強制冷却を行なう場合は、熱処理コイル6中央部に位置する熱延鋼帯1の冷却を促進するために、熱処理コイル6を巻替える工程を設けても良い。   Moreover, when performing forced cooling after heat retention, in order to accelerate | stimulate cooling of the hot-rolled steel strip 1 located in the center part of the heat processing coil 6, you may provide the process of rewinding the heat processing coil 6. FIG.

以上に説明した通り、本発明によれば、従来のバッチ焼鈍のように熱延鋼帯をコイルに巻いた状態で加熱する技術と比べて、極めて短時間で所定の温度まで熱延鋼帯を加熱することができるので、熱処理全体の所要時間を大幅に短縮することができる。また、熱延鋼帯を高温のままで巻取るので、放冷に起因する温度低下を抑制でき、熱延鋼帯の軟質化や組織制御に要する時間を確保できる。   As described above, according to the present invention, the hot-rolled steel strip is heated to a predetermined temperature in a very short time compared to the technique of heating a hot-rolled steel strip wound around a coil as in conventional batch annealing. Since it can be heated, the time required for the entire heat treatment can be greatly reduced. In addition, since the hot-rolled steel strip is wound at a high temperature, a temperature decrease due to cooling can be suppressed, and the time required for softening the hot-rolled steel strip and controlling the structure can be secured.

しかも、熱延鋼帯の成分に応じて熱処理条件(すなわち鋼帯加熱手段の加熱温度、保熱手段の保熱温度と保熱時間等)を変更して操業する場合にも、容易に対応することが可能である。   Moreover, even when the heat treatment conditions (that is, the heating temperature of the steel strip heating means, the heat retaining temperature of the heat retaining means and the heat retaining time, etc.) are changed according to the components of the hot rolled steel strip, it can be easily handled. It is possible.

表1に示す成分を有し、残部がFeおよび不可避的不純物からなる鋼を溶製し、連続鋳造で鋼スラブとした。   Steel having the components shown in Table 1 and the balance being Fe and unavoidable impurities was melted to obtain a steel slab by continuous casting.

その鋼スラブを熱間圧延工程に送給して、加熱炉にて1250℃に加熱し、引き続き、仕上げ圧延機(仕上げ圧延温度870℃)にて熱延鋼帯(板厚2.0mm)として、熱延コイルに巻取った。   The steel slab is fed to the hot rolling process, heated to 1250 ° C in a heating furnace, and subsequently hot rolled steel strip (sheet thickness 2.0mm) in a finish rolling mill (finish rolling temperature 870 ° C), It was wound up on a hot rolled coil.

Figure 0006260448
Figure 0006260448

そして、熱延コイルをコイルヤードにて100℃以下まで空冷した後、塩酸の水溶液を用いて酸洗を行なった。   The hot-rolled coil was air-cooled to 100 ° C. or less in a coil yard, and then pickled using an aqueous hydrochloric acid solution.

次いで、熱延コイルを、図1に示す熱処理設備に送給して、熱延コイル2の熱延鋼帯1を巻戻して連続的に搬送しながら、鋼帯加熱手段4として誘導加熱装置を用いて熱延鋼帯1を加熱した後、熱処理コイル6に巻取った。引き続き、保熱手段である保熱カバー11内に熱処理コイル6を収納して保熱した。その保熱カバー11は、補助加熱手段12を装着していないものを使用した。熱処理コイル6を収納して保熱したときの、保熱カバー11内の温度(以下、保熱温度という)と保熱時間は、表1に示す通りである。   Subsequently, the hot-rolled coil is fed to the heat treatment facility shown in FIG. 1, and the hot-rolled steel strip 1 of the hot-rolled coil 2 is rewound and continuously conveyed, and an induction heating device is used as the steel strip heating means 4. The hot-rolled steel strip 1 was used to heat and then wound on a heat treatment coil 6. Subsequently, the heat treatment coil 6 was housed in a heat retaining cover 11 serving as heat retaining means to retain heat. As the heat insulating cover 11, a cover without the auxiliary heating means 12 was used. Table 1 shows the temperature in the heat retaining cover 11 (hereinafter referred to as the heat retaining temperature) and the heat retaining time when the heat treatment coil 6 is housed and retained.

なお、鋼帯加熱手段4においては、熱延鋼帯の温度を、誘導加熱装置の下流側に設置した放射温度計で測定し、その測定値に応じて熱延鋼帯の搬送速度(基準値15m/分)と誘導加熱装置の出力(基準値2MW)を調整して、保熱温度+40℃に加熱した。つまり使用した熱処理設備では、鋼帯温度差と、その後の保熱手段への搬送中に生じる温度差と、の合計が40℃である。   In the steel strip heating means 4, the temperature of the hot-rolled steel strip is measured with a radiation thermometer installed on the downstream side of the induction heating device, and the conveying speed (reference value) of the hot-rolled steel strip is determined according to the measured value. 15 m / min) and the output of the induction heating device (reference value 2 MW) were adjusted to heat to the heat retention temperature + 40 ° C. That is, in the heat treatment equipment used, the sum of the steel strip temperature difference and the temperature difference generated during the subsequent conveyance to the heat retaining means is 40 ° C.

保熱カバー11による保熱が終了した後、熱処理コイル6をコイルヤードに搬送して、100℃以下まで空冷した。   After the heat insulation by the heat insulation cover 11 was completed, the heat treatment coil 6 was transported to the coil yard and air-cooled to 100 ° C. or lower.

以上の手順の各過程に要した所要時間を表2に示す。表2に示す例は、全て発明例である。   Table 2 shows the time required for each process of the above procedure. The examples shown in Table 2 are all inventive examples.

Figure 0006260448
Figure 0006260448

発明例は、巻取り手段7を断熱材で覆わず、鋼帯加熱手段4と保熱手段(保熱カバー11)を分離して操業するので、熱延鋼帯1を連続的に加熱できる。したがって、表2から明らかなように、熱処理(すなわち昇温および保熱)と、その後の冷却に要する所要時間は合計22.6〜27.6時間であり、いずれも30時間以内で完了した。   In the invention example, since the winding means 7 is not covered with a heat insulating material and the steel strip heating means 4 and the heat retaining means (heat retaining cover 11) are separated and operated, the hot rolled steel strip 1 can be continuously heated. Therefore, as is clear from Table 2, the total time required for heat treatment (ie, temperature increase and heat retention) and subsequent cooling was 22.6 to 27.6 hours, and both were completed within 30 hours.

表1に示すような成分が異なる熱延鋼帯A〜Dを処理する場合は、4個の熱延コイル2を次々に供給して、鋼帯加熱手段4を操業しながら巻取った熱処理コイル6を、4個の保熱カバー11にそれぞれ収納すれば、120時間以内に熱延鋼帯A〜Dの熱処理と冷却を完了することができる。   When processing hot-rolled steel strips A to D having different components as shown in Table 1, four hot-rolled coils 2 are supplied one after another and the heat-treated coil wound up while operating the steel strip heating means 4 6 is housed in each of the four heat retaining covers 11, the heat treatment and cooling of the hot-rolled steel strips A to D can be completed within 120 hours.

これに対して、比較例として、複数の熱延コイル2を大型のベル15に収納して、バッチ焼鈍炉に装入した例について、図4を参照して説明する。このベル15は、スペーサー16を挟んで、熱延コイル2を4段積みできるが、表1に示すような成分が異なる熱延鋼帯A〜Dを一度に収納することはできない。何故なら、熱延鋼帯A〜Dは、いずれも成分が異なるので、それぞれ熱処理条件も異なるからである。   On the other hand, as a comparative example, an example in which a plurality of hot rolled coils 2 are housed in a large bell 15 and charged in a batch annealing furnace will be described with reference to FIG. This bell 15 can stack four stages of hot-rolled coils 2 with a spacer 16 in between, but cannot store hot-rolled steel strips A to D having different components as shown in Table 1 at a time. This is because the hot-rolled steel strips A to D all have different components and therefore have different heat treatment conditions.

バッチ焼鈍炉では、図4に示すように、熱延鋼帯1を熱延コイル2に巻取った状態で加熱するので、熱延コイル2を装入してその中央部が所定の温度に到達するまでに約22時間を要し、熱延コイル2の装入から100℃以下に空冷するまでの全所要時間は40〜46時間である。   In the batch annealing furnace, as shown in FIG. 4, since the hot-rolled steel strip 1 is heated in the state of being wound around the hot-rolled coil 2, the hot-rolled coil 2 is inserted and its central portion reaches a predetermined temperature. It takes about 22 hours to complete, and the total time required from the insertion of the hot-rolled coil 2 to air cooling to 100 ° C. or less is 40 to 46 hours.

したがって、表1に示すような成分が異なる熱延鋼帯A〜Dを熱処理する場合は、冷却終了まで180時間程度を要する。つまり比較例は、発明例よりも処理能率が大幅に劣っている。   Therefore, when heat-treating hot-rolled steel strips A to D having different components as shown in Table 1, it takes about 180 hours to complete the cooling. That is, the processing efficiency of the comparative example is significantly inferior to that of the inventive example.

1 熱延鋼帯
2 熱延コイル
3 巻戻し手段
4 鋼帯加熱手段
5 ブライドルロール
6 熱処理コイル
7 巻取り手段
8 加熱スリーブ
9 断熱スリーブ
10 搬送手段
11 保熱カバー
12 補助加熱手段
13 雰囲気制御装置
14 ピット
15 ベル
16 スペーサー
DESCRIPTION OF SYMBOLS 1 Hot-rolled steel strip 2 Hot-rolled coil 3 Rewinding means 4 Steel-band heating means 5 Bridle roll 6 Heat treatment coil 7 Winding means 8 Heating sleeve 9 Thermal insulation sleeve
10 Transport means
11 Thermal insulation cover
12 Auxiliary heating means
13 Atmosphere control device
14 pits
15 bell
16 Spacer

Claims (3)

熱延鋼帯に熱処理を施す熱処理設備であって、前記熱延鋼帯を巻取った熱延コイルから前記熱延鋼帯を巻戻して連続的に供給する巻戻し手段と、
該巻戻し手段から供給される前記熱延鋼帯を不活性ガス雰囲気内で500℃以上に加熱する鋼帯加熱手段と、
該鋼帯加熱手段の出側で該鋼帯加熱手段における加熱温度と熱処理コイルとして巻取るときの巻取り温度との差を100℃以内として前記熱延鋼帯を前記熱処理コイルとして巻取る巻取り手段と、
前記鋼帯加熱手段の出側から前記巻取り手段に至る搬送経路の一部または全部をカバーし、その内部を不活性ガス雰囲気とする前記搬送経路と、
前記巻取り手段から前記熱処理コイルを搬出するコイル搬送台車、クレーンまたはフォークリフトである搬送手段と、
該搬送手段で搬送された前記熱処理コイルを不活性ガス雰囲気内で所定の時間にわたって保熱する保熱手段と、を有することを特徴とする熱延鋼帯の熱処理設備。
Rewinding means for performing heat treatment on the hot-rolled steel strip, and continuously rewinding and supplying the hot-rolled steel strip from a hot-rolled coil wound with the hot-rolled steel strip;
A steel strip heating means for heating the hot-rolled steel strip supplied from the unwinding means to 500 ° C. or higher in an inert gas atmosphere;
Winding to wind the hot-rolled steel strip as the heat treatment coil with the difference between the heating temperature in the steel strip heating means and the winding temperature when winding as a heat treatment coil within 100 ° C. on the exit side of the steel strip heating means Means,
Covering a part or all of the transport path from the exit side of the steel strip heating means to the winding means, the transport path having an inert gas atmosphere inside ,
A transfer means that is a coil transfer carriage, a crane or a forklift for carrying out the heat treatment coil from the winding means;
Heat treatment equipment for a hot-rolled steel strip, comprising: heat retention means for retaining the heat treatment coil conveyed by the conveyance means for a predetermined time in an inert gas atmosphere.
前記鋼帯加熱手段が、誘導加熱で前記熱延鋼帯を昇温することを特徴とする請求項1に記載の熱延鋼帯の熱処理設備。   The heat treatment equipment for a hot-rolled steel strip according to claim 1, wherein the steel strip heating means raises the temperature of the hot-rolled steel strip by induction heating. 前記保熱手段が前記熱処理コイルを覆う保熱カバーを有し、該保熱カバーがその内部温度を500℃以上に維持する補助加熱手段を有することを特徴とする請求項1または2に記載の熱延鋼帯の熱処理設備。
The heat retention means has a heat retention cover that covers the heat treatment coil, and the heat retention cover has auxiliary heating means for maintaining the internal temperature at 500 ° C. or higher. Heat treatment equipment for hot-rolled steel strip.
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