JP5839177B2 - Finishing annealing equipment and finishing annealing method for grain-oriented electrical steel sheets - Google Patents

Finishing annealing equipment and finishing annealing method for grain-oriented electrical steel sheets Download PDF

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JP5839177B2
JP5839177B2 JP2011224016A JP2011224016A JP5839177B2 JP 5839177 B2 JP5839177 B2 JP 5839177B2 JP 2011224016 A JP2011224016 A JP 2011224016A JP 2011224016 A JP2011224016 A JP 2011224016A JP 5839177 B2 JP5839177 B2 JP 5839177B2
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coil
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啓之 福田
啓之 福田
広和 杉原
広和 杉原
啓介 森
啓介 森
新司 小関
新司 小関
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JFE Steel Corp
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Description

本発明は、方向性電磁鋼板の仕上焼鈍技術に関するものであり、具体的には方向性電磁鋼板の二次再結晶焼鈍および純化焼鈍に用いる仕上焼鈍設備と、その設備を用いた仕上焼鈍方法に関するものである。   TECHNICAL FIELD The present invention relates to a finish annealing technique for grain-oriented electrical steel sheets, and specifically relates to finish annealing equipment used for secondary recrystallization annealing and purification annealing of grain-oriented electrical steel sheets, and a finish annealing method using the equipment. Is.

方向性電磁鋼板は、一般に、以下のようにして製造される。まず、製鋼工程で、Siを3mass%程度含有する鋼を溶製し、連続鋳造法等で鋳片(鋼スラブ)とした後、そのスラブを再加熱した後、熱間圧延して熱延板とし、必要に応じて熱延板焼鈍を施した後、1回または中間焼鈍を挟む2回以上の冷間圧延により最終板厚の冷延板とし、その後、脱炭焼鈍を兼ねた一次再結晶焼鈍を施した後、鋼板表面に焼鈍分離剤を塗布してコイルに巻取る。その後、そのコイルを、図2に示したように、コイル1の巻取軸が垂直となる、いわゆる「アップエンド」の状態にしてバッチ式の箱型焼鈍炉のコイル置台2上に載置し、その上にインナーケース(「インナーカバー」とも称される。)3を被せ、さらにその上に加熱炉4を被せて、加熱バーナー5でインナーケース外部から内部のコイルを加熱し、仕上焼鈍する。その後、仕上焼鈍後のコイルを巻き戻し、鋼板表面に残された焼鈍分離剤を除去した後、絶縁被膜の塗布・焼付等の各種表面処理や平坦化処理を施して製品(方向性電磁鋼板)とする。   A grain-oriented electrical steel sheet is generally manufactured as follows. First, in a steelmaking process, steel containing about 3 mass% of Si is melted and made into a slab (steel slab) by a continuous casting method or the like, then the slab is reheated, and then hot-rolled and hot rolled. And after performing hot-rolled sheet annealing as necessary, it is made into a cold-rolled sheet of the final sheet thickness by cold rolling at least once with intermediate or intermediate annealing, followed by primary recrystallization that also serves as decarburization annealing After annealing, the steel sheet surface is coated with an annealing separator and wound on a coil. Thereafter, as shown in FIG. 2, the coil is placed on the coil mount 2 of the batch type box-type annealing furnace in a so-called “up-end” state in which the winding axis of the coil 1 is vertical. Then, an inner case (also referred to as “inner cover”) 3 is placed thereon, and a heating furnace 4 is further placed thereon, and the internal coil is heated from the outside of the inner case by a heating burner 5 and finish annealing is performed. . Thereafter, the coil after finish annealing is rewound to remove the annealing separator left on the steel sheet surface, and then subjected to various surface treatments such as coating and baking of an insulating coating and flattening treatment (orientated electrical steel sheet). And

ここで、方向性電磁鋼板の仕上焼鈍に用いる上記インナーケースは、アップエンドに載置した電磁鋼板の素材コイルの所定位置(例えば、コイルの外面側や内面側の所定の位置)を温度管理ポイントとし、その管理ポイントを所定温度まで加熱する加熱過程と、その温度に所定の時間保持する均熱過程および上記均熱温度から所定の温度まで冷却する冷却過程の全ての過程において、電磁鋼板と接触するガスを所定の成分組成の雰囲気ガスとし、加熱炉内の雰囲気から遮蔽することによって、良好な二次再結晶を起こさせると共に、その後の純化を適切に行わせる役目を担うものである。   Here, the inner case used for the finish annealing of the grain-oriented electrical steel sheet is a temperature management point at a predetermined position (for example, a predetermined position on the outer surface side or inner surface side) of the coil of the electromagnetic steel sheet placed on the up end. In all of the heating process for heating the control point to a predetermined temperature, the soaking process for maintaining the temperature for a predetermined time, and the cooling process for cooling from the soaking temperature to the predetermined temperature, contact with the electrical steel sheet The gas to be used is an atmospheric gas having a predetermined component composition, and is shielded from the atmosphere in the heating furnace, thereby causing good secondary recrystallization and appropriately performing subsequent purification.

ところで、従来から、上記のようなインナーケースを用いて方向性電磁鋼板の仕上焼鈍を行うと、加熱過程と冷却過程において、コイル内各位置の温度に大きな不均一が生じることが知られている。そして、この温度不均一に起因して、例えば、加熱、均熱過程では他の部分より高速昇温されて高温となる一方、冷却過程では他の部分よりも急速冷却されるコイル外周部分では、「腹伸び」や「縦じわ」などの形状不良が発生し、一方、他の部分より加熱され難いコイル中巻き部(コイル径方向中央部)では、焼鈍不足となって磁気特性が低下する等の不具合が発生していた。   By the way, conventionally, when finish annealing of a grain-oriented electrical steel sheet is performed using the inner case as described above, it is known that a large nonuniformity occurs in the temperature at each position in the coil in the heating process and the cooling process. . And due to this temperature non-uniformity, for example, in the heating and soaking process, the temperature rises faster than the other part and becomes high temperature, while in the cooling process, the coil outer peripheral part that is cooled more rapidly than the other part, Form defects such as “belly stretch” and “vertical wrinkles” occur. On the other hand, in the middle winding portion of the coil (coil radial center) that is harder to be heated than other portions, the annealing is insufficient and the magnetic properties deteriorate. Etc. had occurred.

そこで、コイル内各位置間の温度不均一を改善するインナーケースが幾つか提案されている。例えば、特許文献1には、インナーカバー側壁の内壁側に断熱材を張り付けることで、コイル端面側の過加熱を防止し、コイルの最外巻き寄りの鋼帯層に発生する「縦じわ」を防止する技術が開示されている。
また、特許文献2には、移動炉床式連続熱処理において、冷却過程の所定温度区間において、被熱処理品に断熱カバーを被せることで、被熱処理品内の冷却むらを抑制し、耳歪(耳伸び)を防止する技術が開示されている。
また、特許文献3には、インナーケースの上部に円筒状の凹部を設けることによって、加熱過程および冷却過程で発生するコイル内温度の不均一を改善し、形状不良や磁気特性の劣化を抑制する技術が開示されている。
Thus, several inner cases for improving temperature non-uniformity between positions in the coil have been proposed. For example, in Patent Document 1, a heat insulating material is attached to the inner wall side of the inner cover side wall to prevent overheating on the coil end surface side, and the “longitudinal wrinkle” generated in the steel strip layer near the outermost winding of the coil. Is disclosed.
Further, in Patent Document 2, in the moving hearth type continuous heat treatment, the heat treatment product is covered with a heat insulating cover in a predetermined temperature section of the cooling process, thereby suppressing the cooling unevenness in the heat treatment product, and the ear distortion (the ear distortion). A technique for preventing (elongation) is disclosed.
Further, in Patent Document 3, by providing a cylindrical recess in the upper part of the inner case, non-uniformity of the temperature in the coil generated during the heating process and cooling process is improved, and shape defects and deterioration of magnetic characteristics are suppressed. Technology is disclosed.

特開2006−257486号公報JP 2006-257486 A 特開平05−271790号公報JP 05-271790 A 特開2008−195998号公報JP 2008-195998 A

しかしながら、特許文献1や2に記載されたコイル外周部の過加熱や過冷却を防止する技術には、以下のような問題がある。例えば、特許文献1に記載のインナーケースを用いる技術では、コイル上部の過加熱を防止することができたとしても、インナーケースの側壁とそれと向かい合うコイル外周面との間の熱の授受が断熱材によって阻害されるため、仕上焼鈍の加熱時間および冷却時間が大幅に延長され、生産性の著しい低下を招く。また、特許文献2に記載の断熱カバーを被せる技術では、冷却帯の所定箇所に断熱カバーを被熱処理品に被せるための装置と、これとは別に、断熱カバーを回収するための装置とを備えることが必要となるため、設備コストの上昇を招く。   However, the techniques described in Patent Documents 1 and 2 for preventing overheating and overcooling of the outer periphery of the coil have the following problems. For example, in the technique using the inner case described in Patent Document 1, even if the overheating of the upper part of the coil can be prevented, the heat transfer between the side wall of the inner case and the outer peripheral surface of the coil facing the heat insulating material Therefore, the heating time and cooling time of finish annealing are greatly extended, and the productivity is significantly reduced. Moreover, in the technique which covers the heat insulation cover of patent document 2, the apparatus for putting a heat insulation cover on a to-be-heat-processed article in the predetermined location of a cooling zone, and the apparatus for collect | recovering heat insulation covers are provided separately from this. This increases equipment costs.

一方、特許文献3に記載されたインナーケースでは、上記問題点はないものの、図3に示すように、冷却過程においては、冷却ノズル6から噴出した冷却ガス7がインナーケースに設けられた円筒状凹部8の下部まで到達しないため、円筒状凹部8の上部しか冷却されない。そのため、コイル上部側しか温度の不均一分布が改善されず、コイル下部側は、依然として冷却過程で発生する温度の不均一分布によって、形状不良が発生したり、磁気特性の劣化が起こったりするという問題がある。   On the other hand, the inner case described in Patent Document 3 does not have the above problem, but as shown in FIG. 3, in the cooling process, a cooling gas 7 ejected from the cooling nozzle 6 is provided in a cylindrical shape provided in the inner case. Since it does not reach the lower part of the concave part 8, only the upper part of the cylindrical concave part 8 is cooled. For this reason, the uneven distribution of temperature is improved only on the upper side of the coil, and the lower part of the coil still has a non-uniform distribution of temperature generated in the cooling process, resulting in shape defects and deterioration of magnetic characteristics. There's a problem.

本発明は、従来技術が抱える上記問題点に鑑みてなされたものであり、その目的は、方向性電磁鋼板をバッチ式の箱型焼鈍炉を用いて仕上焼鈍する際に発生する、コイル内温度分布の不均一を改善し、形状不良および鉄損劣化を効果的に抑制することができる仕上焼鈍設備と、その設備を用いた方向性電磁鋼板の仕上焼鈍方法を提案することにある。   The present invention has been made in view of the above-mentioned problems of the prior art, and the purpose thereof is the temperature in the coil that is generated when a directional electrical steel sheet is subjected to finish annealing using a batch-type box annealing furnace. The object is to propose a finish annealing facility capable of improving unevenness of distribution and effectively suppressing shape defects and iron loss deterioration, and a method of finish annealing of grain-oriented electrical steel sheets using the facility.

発明者らは、生産性を害することなく上記課題を解決するべく、加熱過程および冷却過程で生じるコイル内温度の不均一分布を改善する方法について鋭意検討した。その結果、焼鈍設備のコイル置台上面に、コイル内径部に挿入する、内管と外管からなる2重管構造の冷却管を立設し、その内部に冷却ガスを流して外管を冷却することによって、仕上焼鈍の加熱過程および冷却過程におけるコイル内温度分布の不均一を大幅に軽減し得ることを見出し、本発明を開発するに至った。   The inventors diligently studied a method for improving the non-uniform distribution of the temperature in the coil generated in the heating process and the cooling process in order to solve the above-mentioned problems without impairing the productivity. As a result, a cooling pipe having a double-pipe structure composed of an inner pipe and an outer pipe, which is inserted into the inner diameter portion of the coil, is erected on the upper surface of the coil base of the annealing equipment, and the outer pipe is cooled by flowing a cooling gas therein As a result, it has been found that the non-uniformity of the temperature distribution in the coil in the heating process and cooling process of finish annealing can be greatly reduced, and the present invention has been developed.

すなわち、本発明は、方向性電磁鋼板の仕上焼鈍に用いるバッチ式の箱型焼鈍設備であって、コイル置台上にアップエンドに載置されたコイル内径部に挿入される、上方を閉じた外管とその内部に円筒状の内管を有する2重管構造で、外管外径がコイル内径の0.3倍以上であり、かつ、外管外周面とコイル内周面とが50mm以上離間している冷却管を立設してなることを特徴とする仕上焼鈍設備である。 That is, the present invention is a batch type box-type annealing equipment used for finish annealing of grain-oriented electrical steel sheets, and is inserted into a coil inner diameter portion mounted on an up-end on a coil mounting base, and has an outer top closed. A double pipe structure with a pipe and a cylindrical inner pipe inside , the outer diameter of the outer pipe is not less than 0.3 times the inner diameter of the coil, and the outer peripheral surface of the outer pipe and the inner peripheral surface of the coil are separated by 50 mm or more. The finish annealing equipment is characterized in that a cooling pipe is installed upright.

また、本発明の仕上焼鈍設備における上記冷却管は、内管の内側断面積が、外管の内側断面積の0.3〜0.7倍であることを特徴とする。   The cooling pipe in the finish annealing facility of the present invention is characterized in that the inner cross-sectional area of the inner pipe is 0.3 to 0.7 times the inner cross-sectional area of the outer pipe.

また、本発明は、上記のいずれかに記載の仕上焼鈍設備を用いる方向性電磁鋼板の仕上焼鈍方法であって、上記2重管構造の冷却管内に冷却ガスを流しながら仕上焼鈍することを特徴とする方向性電磁鋼板の仕上焼鈍方法である。   Moreover, the present invention is a finish annealing method for grain-oriented electrical steel sheets using the finish annealing equipment described in any of the above, wherein the finish annealing is performed while flowing a cooling gas into the cooling pipe having the double pipe structure. It is the finishing annealing method of the grain-oriented electrical steel sheet.

本発明の仕上焼鈍方法は、上記冷却ガスを、内管下方から冷却管内に導入し、外管と内管の間を上方から下方に向かって排出する、あるいは、外管と内管の間の下方から冷却管内に導入し、内管の上方から下方に向かって排出することを特徴とする。 In the finish annealing method of the present invention, the cooling gas is introduced into the cooling pipe from below the inner pipe and discharged between the outer pipe and the inner pipe from the upper side to the lower side, or between the outer pipe and the inner pipe. It introduce | transduces in a cooling pipe from the downward direction, It is characterized by discharging | emitting from the upper direction of an inner pipe toward the downward direction.

また、本発明の仕上焼鈍方法は、上記内管と外管の間の冷却ガスの流速を5m/s以上とすることを特徴とする。   The finish annealing method of the present invention is characterized in that the flow rate of the cooling gas between the inner pipe and the outer pipe is 5 m / s or more.

本発明によれば、コイル内径部分に挿入した冷却管でコイル内周面を冷却することで、仕上焼鈍時に発生するコイル内温度分布の不均一に起因して生じる圧縮応力による形状不良や磁気特性の劣化を抑制することができるので、方向性電磁鋼板の歩留り向上や品質向上に大きく寄与する。また、本発明によれば、コイル内の温度分布が改善されることから、インナーケース内の雰囲気も早く冷却でき、結果としてコイル全体の冷却を促進することができるので、冷却時間が短縮されて、生産性の向上にも寄与することができる。   According to the present invention, by cooling the inner peripheral surface of the coil with a cooling pipe inserted in the inner diameter portion of the coil, shape defects and magnetic characteristics due to compressive stress caused by non-uniform temperature distribution in the coil generated during finish annealing. Therefore, it greatly contributes to the improvement in yield and quality of grain-oriented electrical steel sheets. Further, according to the present invention, since the temperature distribution in the coil is improved, the atmosphere in the inner case can be quickly cooled, and as a result, the cooling of the entire coil can be promoted, so that the cooling time is shortened. It can also contribute to the improvement of productivity.

本発明に係る仕上焼鈍設備を説明する縦断面図である。It is a longitudinal section explaining finishing annealing equipment concerning the present invention. 従来技術の仕上焼鈍設備を説明する縦断面図である。It is a longitudinal cross-sectional view explaining the finish annealing equipment of a prior art. 特許文献3の仕上焼鈍設備の問題点を説明する図である。It is a figure explaining the problem of the finish annealing equipment of patent documents 3. 従来技術の仕上焼鈍設備における、加熱過程でのコイル半径方向の温度分布を示す模式図である。It is a schematic diagram which shows the temperature distribution of the coil radial direction in the heating process in the finish annealing equipment of a prior art. 従来技術の仕上焼鈍設備における、冷却過程でのコイル半径方向の温度分布を示す模式図である。It is a schematic diagram which shows the temperature distribution of the coil radial direction in the cooling process in the finish annealing equipment of a prior art. 従来技術の仕上焼鈍設備における、コイル内周面A点の加熱に寄与する輻射熱発生部位を示す模式図である。It is a schematic diagram which shows the radiant heat generation site | part which contributes to the heating of the coil internal peripheral surface A point in the finish annealing equipment of a prior art. 特許文献3の仕上焼鈍設備における、コイル内周面A点の加熱に寄与する輻射熱発生部位を示す模式図である。It is a schematic diagram which shows the radiant heat generation site | part which contributes to the heating of the coil internal peripheral surface A point in the finish annealing equipment of patent document 3. FIG. 本発明の仕上焼鈍設備における、コイル内周面A点の加熱に寄与する輻射熱発生部位を示す模式図である。It is a schematic diagram which shows the radiant heat generation site | part which contributes to the heating of the coil internal peripheral surface A point in the finish annealing equipment of this invention. 本発明の冷却管の外管寸法が、コイル内周面P点の冷却に及ぼす影響を説明する横断面図である。It is a cross-sectional view explaining the influence which the outer tube | pipe dimension of the cooling tube of this invention has on cooling of the coil internal peripheral surface P point. 加熱過程でのコイル半径方向の温度分布を、本発明例と従来技術の比較例と対比して示す図である。It is a figure which shows the temperature distribution of the coil radial direction in a heating process in contrast with the example of this invention, and the comparative example of a prior art. 冷却過程でのコイル半径方向の温度分布を、本発明例と従来技術の比較例と対比して示す図である。It is a figure which shows the temperature distribution of the coil radial direction in a cooling process in contrast with the example of this invention, and the comparative example of a prior art.

まず、本発明の基本的技術思想について説明する。
方向性電磁鋼板の仕上焼鈍には、一般に、加熱バーナーから燃焼ガスを噴き出して加熱するバッチ式の箱型焼鈍炉が用いられている。この焼鈍炉を用いた仕上焼鈍は、上記加熱バーナーによってインナーケースを加熱して、その内部に載置されたコイルを所定の均熱温度まで加熱(加熱過程)し、その均熱温度に所定の時間保持(均熱過程)後、バーナーを停止し、加熱炉の上方に設けられた冷却ノズルから冷却ガスをインナーカバーの上面に向けて噴出してインナーカバーを冷却し、その内部のコイルが所定の温度まで冷却(冷却過程)することでなされる。
First, the basic technical idea of the present invention will be described.
For finish annealing of grain-oriented electrical steel sheets, a batch type box annealing furnace is generally used in which combustion gas is blown from a heating burner and heated. In the finish annealing using this annealing furnace, the inner case is heated by the heating burner, and the coil placed inside is heated to a predetermined soaking temperature (heating process). After holding the time (soaking process), the burner is stopped, the cooling gas is jetted from the cooling nozzle provided above the heating furnace toward the upper surface of the inner cover, the inner cover is cooled, and the coil inside thereof is predetermined. This is done by cooling to a temperature of (cooling process).

なお、上記仕上焼鈍においては、一般に、インナーケース内に載置されたコイルの半径方向の所定位置を温度管理ポイントと設定し、そのポイントの測温値と、予定の焼鈍サイクルとを対比することで、加熱バーナーから噴き出す燃焼ガスの燃焼制御が行われている。この燃焼ガスは、焼鈍炉(加熱炉)の炉内雰囲気となる。
一方、インナーケース内の雰囲気は、鋼板の酸化を抑制すると共に、好ましい二次再結晶等を起こさせるため、上記炉内雰囲気とは別の還元性雰囲気に制御される。
In the above-mentioned finish annealing, generally, a predetermined position in the radial direction of the coil placed in the inner case is set as a temperature management point, and a temperature measurement value at that point is compared with a planned annealing cycle. Thus, combustion control of the combustion gas ejected from the heating burner is performed. This combustion gas becomes the furnace atmosphere of the annealing furnace (heating furnace).
On the other hand, the atmosphere in the inner case is controlled to be a reducing atmosphere different from the furnace atmosphere in order to suppress oxidation of the steel sheet and cause preferable secondary recrystallization.

ここで、方向性電磁鋼板を仕上焼鈍する際、加熱過程で発生するコイル半径方向のコイル内温度分布につい説明する。
まず、図2に示した従来技術の仕上焼鈍設備を用いて仕上焼鈍する際におけるコイルへの熱の授受は、主にインナーケースの側面および上面からの輻射熱によって行われる。したがって、加熱過程および均熱過程の前半では、コイル外周面側、コイル上側面側、次いでコイル内周面側の順に昇温され、その後、熱伝導によってコイル内部に熱が供給されて、コイル半径方向中央部(以降、「中巻部」とも称する。)およびコイル下側面側の昇温が進む。その結果、コイル半径方向における温度分布は、図4に示すように、コイル外周面側が最も高く、次いで内周面側となり、中巻部が最も低い分布を示す。このようなコイル半径方向の温度分布となると、中巻部の熱膨張量よりも内周面側の熱膨張量の方が大きくなる。その結果、内周面側は、中巻部からコイル半径方向に大きな圧縮応力を受けることになる。
Here, a description will be given of the temperature distribution in the coil in the radial direction of the coil that occurs in the heating process when the grain-oriented electrical steel sheet is subjected to finish annealing.
First, transfer of heat to the coil when performing finish annealing using the finish annealing equipment of the prior art shown in FIG. 2 is performed mainly by radiant heat from the side surface and the top surface of the inner case. Therefore, in the first half of the heating process and the soaking process, the temperature is increased in the order of the coil outer peripheral surface side, the coil upper surface side, and then the coil inner peripheral surface side. The temperature rises in the central portion in the direction (hereinafter also referred to as “middle winding portion”) and the coil lower surface side. As a result, as shown in FIG. 4, the temperature distribution in the coil radial direction is highest on the outer peripheral surface side of the coil, then on the inner peripheral surface side, and shows the lowest distribution in the middle winding portion. When such a temperature distribution in the coil radial direction is obtained, the amount of thermal expansion on the inner peripheral surface side becomes larger than the amount of thermal expansion of the middle winding portion. As a result, the inner peripheral surface side receives a large compressive stress from the middle winding portion in the coil radial direction.

次に、従来技術の仕上焼鈍設備を用いて仕上焼鈍する際、冷却過程で発生するコイル半径方向のコイル内温度分布について説明する。
先述したように、冷却過程でのコイルの冷却は、加熱炉上部の冷却ノズルからインナーケース上部に冷却用ガスを吹き付けることで行われる。そのため、この冷却過程では、まず、インナーケースの温度が低下し、次いで、コイルの外周面側、上側面側、内周面側の順に温度が降下し、その後、熱伝導によってコイルの中巻部および下方側(下側面)の降温が進む。その結果、コイル半径方向における温度は、図5に示すように、コイル中巻部が最も高く、次いで内周面側となり、外周面側が最も低い温度分布を示すようになる。このようなコイル半径方向の温度分布となると、中巻部の熱収縮量より、外周面側の熱収縮量の方が大きくなる。その結果、コイル中巻部の鋼板は、外周面側からコイル半径方向に大きな圧縮応力を受けることになる。
Next, the temperature distribution in the coil in the radial direction of the coil that occurs during the cooling process when the finish annealing is performed using the finish annealing equipment of the prior art will be described.
As described above, the cooling of the coil in the cooling process is performed by blowing the cooling gas from the cooling nozzle in the upper part of the heating furnace to the upper part of the inner case. Therefore, in this cooling process, the temperature of the inner case first decreases, and then the temperature decreases in the order of the outer peripheral surface side, the upper side surface, and the inner peripheral surface side of the coil. And the temperature lowering on the lower side (lower side) proceeds. As a result, as shown in FIG. 5, the temperature in the coil radial direction is highest at the middle winding portion of the coil, then at the inner peripheral surface side, and at the outer peripheral surface side shows the lowest temperature distribution. With such a temperature distribution in the coil radial direction, the amount of heat shrinkage on the outer peripheral surface side becomes larger than the amount of heat shrinkage on the middle winding portion. As a result, the steel sheet in the middle winding part of the coil receives a large compressive stress in the coil radial direction from the outer peripheral surface side.

そして、発明者らの研究によれば、上記加熱過程および冷却過程において、コイル内周面部やコイル中巻部に発生する圧縮応力は、「耳延び」や「縦じわ」等の形状不良を引き起こすのみならず、磁気特性(鉄損)の劣化をも引き起こす原因となっていることが明らかとなった。圧縮応力によって鉄損特性が劣化する原因は、圧縮応力が大きくなると、コイル層間距離が縮まって、インナーケース内の雰囲気ガスが鋼板間に十分に流れなくなり、二次再結晶や純化に悪影響を及ぼすためと考えている。したがって、仕上焼鈍時に発生する圧縮応力は、いずれの過程においても極力低減する必要がある。   According to the researches of the inventors, in the heating process and the cooling process, the compressive stress generated in the inner peripheral surface portion of the coil and the middle winding portion of the coil has a shape defect such as “ear extension” or “vertical wrinkle”. It became clear that not only causing the deterioration but also causing the deterioration of magnetic properties (iron loss). The cause of the deterioration of iron loss characteristics due to compressive stress is that when the compressive stress increases, the coil interlayer distance decreases, and the atmosphere gas in the inner case does not flow sufficiently between the steel plates, adversely affecting secondary recrystallization and purification. I think because. Therefore, it is necessary to reduce the compressive stress generated during finish annealing as much as possible in any process.

そこで、発明者らは、上記仕上焼鈍時に発生する圧縮応力を軽減する方法について検討を重ねた結果、図1に示すように、仕上焼鈍設備のコイル置台中央部に、コイル内径部に挿入する、内管と外管からなる2重管構造の冷却管を立設し、その内部に冷却ガスを流して冷却管の外管を冷却し、コイル内周面側を積極的に冷却することによって、コイル内の温度分布を均一化し、温度不均一によって生じる圧縮応力を大幅に軽減することに成功した。以下、具体的に説明する。   Therefore, as a result of repeated investigations on the method of reducing the compressive stress generated during the finish annealing, the inventors have inserted the coil inner diameter portion into the coil mounting center portion of the finish annealing equipment, as shown in FIG. By installing a cooling pipe with a double pipe structure consisting of an inner pipe and an outer pipe, and cooling the outer pipe of the cooling pipe by flowing cooling gas through the inside, and actively cooling the inner peripheral surface side of the coil, We succeeded in making the temperature distribution in the coil uniform and greatly reducing the compressive stress caused by temperature non-uniformity. This will be specifically described below.

従来技術の仕上焼鈍設備を用いた仕上焼鈍の加熱過程では、コイル内周面側は、インナーケース上面からの輻射熱によって加熱される。すなわち、図6に示すように、インナーケース3上部のB〜B´の部分は、加熱炉4の内壁のC〜C´の部分からの輻射熱で加熱され、コイル内周面のA点は、このB〜B´の部分からの輻射熱によって加熱される。したがって、コイル内周面のA点は、ある意味では効率的に加熱されることになる。   In the heating process of finish annealing using the finish annealing equipment of the prior art, the coil inner peripheral surface side is heated by radiant heat from the upper surface of the inner case. That is, as shown in FIG. 6, the portions B to B ′ above the inner case 3 are heated by radiant heat from the portions C to C ′ on the inner wall of the heating furnace 4, and the point A on the inner peripheral surface of the coil is Heated by the radiant heat from the portions B to B ′. Therefore, the point A on the inner peripheral surface of the coil is heated efficiently in a sense.

また、特許文献3の仕上焼鈍設備を用いた仕上焼鈍の加熱過程では、図7に示すように、コイル内周面のA点は、インナーケース3の円筒状凹部8のD〜D´の部分からの輻射熱によって加熱される。そして、このD〜D´の部分の加熱は、加熱炉4の内壁のE〜E´の部分からインナーケース3のF〜F´の部分を介して行われるため、実質F〜F´の部分の輻射熱によって加熱される。このF〜F´の部分は、図6に示したB〜B´部分より狭い。そのため、加熱炉の内壁温度が同じである場合には、コイル内周面の温度は、図7に示す特許文献3の仕上焼鈍設備の方が、図6に示す従来の仕上焼鈍設備よりも上昇し難くなる。   Moreover, in the heating process of the finish annealing using the finish annealing equipment of patent document 3, as shown in FIG. 7, A point of the coil internal peripheral surface is the part of D-D 'of the cylindrical recessed part 8 of the inner case 3. As shown in FIG. It is heated by radiant heat from. And since the heating of this D-D 'part is performed via the part of F-F' of the inner case 3 from the part of E-E 'of the inner wall of the heating furnace 4, the part of F-F' substantially It is heated by radiant heat. The portions F to F ′ are narrower than the portions B to B ′ shown in FIG. Therefore, when the inner wall temperature of the heating furnace is the same, the temperature of the inner peripheral surface of the coil is higher in the finish annealing facility of Patent Document 3 shown in FIG. 7 than in the conventional finish annealing facility shown in FIG. It becomes difficult to do.

また、本発明の仕上焼鈍設備を用いた仕上焼鈍の加熱過程では、図8に示したように、コイル内径に冷却管9が挿入されているため、コイル内周面のA点は、インナーケース3の頭頂部のI〜I´の部分からの輻射熱によって加熱される。そして、I〜I´の部分は、加熱炉4の内壁のH〜Hの部分の輻射熱によって加熱されるものの、このI〜I´の部分は、図7に示したF〜F´部分よりもさらに狭い。そのため、加熱炉の内壁温度が同じである場合には、コイル内周面の温度は、図7に示す特許文献3の仕上焼鈍設備よりも上昇し難くなる。
さらに、加熱中に冷却管9の内部に冷却ガスを流した場合には、冷却管の外管10のG〜G´の部分が冷却されるので、コイル内周面の輻射熱を吸収し、コイル内周面の加熱はより緩やかになる。その結果、加熱過程においては、コイル内周面側とコイル中巻部との温度差や熱膨張量の差がなくなるため、コイル内周面側に生じるコイル半径方向の圧縮応力は解消されることになる。
Further, in the heating process of the finish annealing using the finish annealing equipment of the present invention, as shown in FIG. 8, since the cooling pipe 9 is inserted into the inner diameter of the coil, the point A on the inner peripheral surface of the coil is the inner case. 3 is heated by radiant heat from the I-I 'portion of the top of the head. And although I-I 'part is heated by the radiant heat of the H-H part of the inner wall of the heating furnace 4, this I-I' part is more than F-F 'part shown in FIG. Narrower. Therefore, when the inner wall temperature of the heating furnace is the same, the temperature of the coil inner peripheral surface is less likely to rise than the finish annealing facility of Patent Document 3 shown in FIG.
Further, when a cooling gas is caused to flow inside the cooling pipe 9 during heating, the portions G to G ′ of the outer pipe 10 of the cooling pipe are cooled, so that the radiant heat of the inner peripheral surface of the coil is absorbed, and the coil The heating of the inner peripheral surface becomes more gradual. As a result, in the heating process, there is no difference in temperature or thermal expansion between the coil inner peripheral surface side and the coil middle winding part, so that the compressive stress in the coil radial direction generated on the coil inner peripheral surface side is eliminated. become.

次に、冷却過程におけるコイル内温度分布についてみると、従来技術の仕上焼鈍設備を用いる場合には、図2に示すように、冷却ガスをインナーケース上面に吹き付けることよって、インナーケース内のコイルを冷却するため、コイル外周面側が優先的に冷却されるものの、コイル内周面側の冷却は大きく遅れることになる。   Next, regarding the temperature distribution in the coil in the cooling process, when using the finish annealing equipment of the prior art, as shown in FIG. 2, the cooling gas is blown onto the upper surface of the inner case, so that the coil in the inner case is In order to cool, although the coil outer peripheral surface side is preferentially cooled, the cooling of the coil inner peripheral surface side is greatly delayed.

これに対して、本発明の冷却管を有する仕上焼鈍設備を用いた場合には、図1に示したように、冷却管の内部に冷却ガスを流して冷却管の外管を冷却するため、図8に示したように、コイル内周面の輻射熱を冷却管の外管で吸収することができる。その結果、コイル内周面側が最も冷却され、次いで、コイル外周面、その後、熱伝導によってコイル中巻部が冷却されるようになる。そして、このような冷却では、コイル内周面側の熱収縮量が最も大きくなるため、コイル中巻部からコイル内周面への圧縮応力は発生しなくなる。   On the other hand, when the finish annealing equipment having the cooling pipe of the present invention is used, as shown in FIG. 1, in order to cool the outer pipe of the cooling pipe by flowing a cooling gas inside the cooling pipe, As shown in FIG. 8, the radiant heat on the inner peripheral surface of the coil can be absorbed by the outer tube of the cooling tube. As a result, the coil inner peripheral surface side is cooled most, and then the coil outer peripheral surface and then the coil middle winding portion is cooled by heat conduction. In such cooling, the amount of thermal shrinkage on the coil inner peripheral surface side becomes the largest, and therefore, compressive stress from the coil middle winding portion to the coil inner peripheral surface is not generated.

上記のように、本発明に係る冷却管は、加熱過程においてコイル内周面側に発生する圧縮応力だけでなく、冷却過程においてコイル内周面側およびコイル中巻部に発生する圧縮応力をも解消することができるので、圧縮応力に起因して発生する形状不良や磁気特性の劣化を大幅に改善することができる。   As described above, the cooling pipe according to the present invention has not only the compressive stress generated on the coil inner peripheral surface side during the heating process, but also the compressive stress generated on the coil inner peripheral surface side and the coil middle winding portion during the cooling process. Since it can be eliminated, it is possible to greatly improve the shape defect and the deterioration of the magnetic characteristics caused by the compressive stress.

さらに、本発明の仕上焼鈍設備では、冷却管を配設したことにより、コイル内周面の冷却が促進されるだけでなく、コイルインナーカバー内の雰囲気ガスも同時に冷却されるので、コイル内周面以外の部分の冷却も促進する効果もある。その結果、本発明の仕上焼鈍設備を用いた場合には、冷却時間を大幅に短縮できるので、生産性が大きく向上する効果も得られる。   Furthermore, in the finish annealing equipment of the present invention, the cooling pipe is provided, so that not only the cooling of the coil inner peripheral surface is promoted, but also the atmospheric gas in the coil inner cover is simultaneously cooled. There is also an effect of promoting cooling of portions other than the surface. As a result, when the finish annealing equipment of the present invention is used, the cooling time can be greatly shortened, so that the effect of greatly improving productivity can be obtained.

次に、本発明の冷却管について説明する。
本発明の冷却管は、上方を閉じた外管とその内部に設けた円筒状の内管の2重構造からなるものである。このような2重構造とする理由は、単なる上方を閉じた外管だけでは、図3のインナーケースの円筒状凹部と同様、冷却ガスが内部まで侵入せず、効率的に冷却管を冷却することが難しいが、2重構造として、例えば図1に示したように、冷却ガスを、内管の下方から導入して、外管頂部で反転させた後、外管と内管の間を上方から下方に流して排出させるようにした場合には、冷却ガスが冷却管内部で滞留を起こすことなくスムーズに流れ、かつ、冷却管の外管を効率よく冷却することが可能となるからである。なお、冷却ガスを流す方向は、図1のように、内管→外管の順である必要はなく、その逆に、外管→内管の順としてもよい。
Next, the cooling pipe of the present invention will be described.
The cooling pipe of the present invention is composed of a double structure of an outer pipe whose upper part is closed and a cylindrical inner pipe provided therein. The reason why such a double structure is used is that the cooling pipe does not penetrate into the inside as in the case of the cylindrical recess of the inner case in FIG. Although it is difficult, as shown in FIG. 1, for example, as shown in FIG. 1, the cooling gas is introduced from the lower side of the inner pipe, reversed at the top of the outer pipe, and then the upper part between the outer pipe and the inner pipe. This is because the cooling gas flows smoothly without stagnation inside the cooling pipe, and the outer pipe of the cooling pipe can be efficiently cooled. . As shown in FIG. 1, the direction in which the cooling gas flows does not have to be in the order of the inner pipe → the outer pipe, and conversely, the order may be the outer pipe → the inner pipe.

また、本発明に係る冷却管は、その冷却効率をより高めるためには、コイルの内径Dに対する冷却管外管の外径Dの比(D/D)が0.3以上であるとともに、コイル内周面と冷却管外管との間が50mm以上離間していることが好ましい。
というのは、コイル内周面を冷却する能力は、冷却管の温度が同じ場合、コイル内周面の面積と、冷却管外管の面積の比、したがって、コイルの内径Dに対する冷却管外管の外径Dの比(D/D)で決定されるからである。すなわち、図9に示すように、(D/D)が大きいほど、コイル内周面のP点からの輻射熱が、冷却管外管に流れる範囲が広くなるので、コイル内周面からの輻射熱を効率よく吸収できる。しかし、(D/D)が0.3未満では、コイル内周面から放散される輻射熱のうち、冷却管の外管表面が受ける輻射熱の割合は19%未満となり、コイル内周面の冷却効率が著しく低下する。よって、(D/D)は0.3以上とするのが好ましい。
また、冷却管外管とコイル内周面との間の距離を50mm以上とする理由は、50mm未満では、コイルをアップエンドにしてコイル置台上に載置する際、冷却管がコイル内径と接触を起こして破損するおそれがあるからである。
In order to further increase the cooling efficiency of the cooling pipe according to the present invention, the ratio (D 2 / D 1 ) of the outer diameter D 2 of the outer pipe of the cooling pipe to the inner diameter D 1 of the coil is 0.3 or more. In addition, it is preferable that the inner peripheral surface of the coil and the outer pipe of the cooling pipe are separated by 50 mm or more.
Because the ability to cool the inside of the coil circumference, when the temperature of the cooling pipe is the same, the area of the coil circumference, the ratio of the area of the cooling tube outer tube, thus, the cooling tube outer to the inner diameter D 1 of the coil This is because it is determined by the ratio (D 2 / D 1 ) of the outer diameter D 2 of the tube. That is, as shown in FIG. 9, as (D 2 / D 1 ) increases, the range in which the radiant heat from the point P on the inner peripheral surface of the coil flows to the outer tube of the cooling pipe becomes wider. Can absorb radiant heat efficiently. However, when (D 2 / D 1 ) is less than 0.3, the ratio of the radiant heat received by the outer surface of the cooling pipe out of the radiant heat dissipated from the inner peripheral surface of the coil is less than 19%. Cooling efficiency is significantly reduced. Therefore, (D 2 / D 1 ) is preferably set to 0.3 or more.
In addition, the reason why the distance between the outer pipe of the cooling pipe and the inner peripheral surface of the coil is 50 mm or more is that when it is less than 50 mm, the cooling pipe comes into contact with the inner diameter of the coil when the coil is placed on the upside with the coil up-end. This is because it may cause damage.

また、本発明の仕上焼鈍設備の冷却管は、内管の内側断面積が、外管の内側断面積の0.3〜0.7倍であることが好ましい。
冷却管の内管の内側断面積が、外管の内側断面積の0.3倍未満では、内管を通る冷却ガスの流量が少なくなり、冷却管の外管を十分に冷却できないため、冷却効率が低下してしまう。一方、内管の内側断面積が、外管の内側断面積の0.7倍より大きくなると、内管と外管との間の流路面積が小さくなり、やはり冷却ガスの流量が減少して、冷却管の外管を十分に冷却できなくなるからである。
In the cooling pipe of the finish annealing equipment of the present invention, the inner cross-sectional area of the inner pipe is preferably 0.3 to 0.7 times the inner cross-sectional area of the outer pipe.
If the inner cross-sectional area of the inner pipe of the cooling pipe is less than 0.3 times the inner cross-sectional area of the outer pipe, the cooling gas flow rate through the inner pipe is reduced, and the outer pipe of the cooling pipe cannot be cooled sufficiently. Efficiency will decrease. On the other hand, when the inner cross-sectional area of the inner pipe is larger than 0.7 times the inner cross-sectional area of the outer pipe, the flow area between the inner pipe and the outer pipe is reduced, and the flow rate of the cooling gas is also reduced. This is because the outer pipe of the cooling pipe cannot be sufficiently cooled.

また、冷却管の内管と外管との間に流す冷却ガスの流速は、冷却管外管のより効率的に冷却する観点からは、5m/s以上とするのが好ましい。5m/s未満では、外管を十分に冷却することができないため、コイル内周面の輻射熱を効率よく吸収できないからである。   The flow rate of the cooling gas flowing between the inner pipe and the outer pipe of the cooling pipe is preferably 5 m / s or more from the viewpoint of more efficiently cooling the cooling pipe outer pipe. If the speed is less than 5 m / s, the outer tube cannot be sufficiently cooled, so that the radiant heat on the inner peripheral surface of the coil cannot be efficiently absorbed.

また、本発明の冷却管は、インナーケースとは分離しているため、冷却管内に流す冷却ガスは、インナーケース内の雰囲気ガスとは異なるものを使用することができる。したがって、大気(空気)を冷却ガスとして使用してもよい。また、この場合には、使用後の冷却ガスは、そのまま大気中に放出することができる。   Further, since the cooling pipe of the present invention is separated from the inner case, the cooling gas flowing into the cooling pipe can be different from the atmospheric gas in the inner case. Therefore, you may use air | atmosphere (air) as a cooling gas. In this case, the used cooling gas can be released into the atmosphere as it is.

なお、上記本発明の説明では、仕上焼鈍設備における冷却管は、コイル置台の中央部に予め立設した場合について説明してきたが、冷却管を取り外し可能とし、コイルを載置した後、冷却管をコイル置台中央部に差し込む構造としてもよいことは勿論である。   In the above description of the present invention, the cooling pipe in the finish annealing equipment has been described in the case where the cooling pipe is erected in the center of the coil mount in advance. However, after the cooling pipe can be removed and the coil is placed, Of course, it is good also as a structure which inserts in the coil base center part.

Siを3mass%含有する、板厚:0.3mm×板幅:1160mm×長さ:3000m(約8.2トン)の方向性電磁鋼板用冷延コイルを一次再結晶焼鈍した後、焼鈍分離剤を鋼板表面に塗布し、コイルに巻き取り、その後、そのコイルをバッチ式箱型焼鈍炉のコイル置台上にアップエンドにして載置し、表1に示した4条件で仕上焼鈍を施した。なお、表1に示した以外の仕上焼鈍条件は表2に示した。
ここで、表1のNo.1〜3は、仕上焼鈍に、図1に示した2重管構造の冷却管を設けた本発明の仕上焼鈍設備を用いた発明例であり、冷却ガスとして空気(エア)を用い、冷却過程における内管と外管の間に流す冷却ガスの流速を、それぞれ2.5m/s、5m/sおよび10m/sの3水準に変化させた。また、表1のNo.4は、図2に示した従来技術の仕上焼鈍設備を用いた比較例である。
After the primary recrystallization annealing of a cold rolled coil for grain-oriented electrical steel sheets containing 3 mass% of Si, plate thickness: 0.3 mm × plate width: 1160 mm × length: 3000 m (about 8.2 tons), annealing separator Was coated on the surface of the steel sheet, wound around a coil, and then the coil was placed up-end on a coil mounting table of a batch type box-type annealing furnace and subjected to finish annealing under the four conditions shown in Table 1. The finish annealing conditions other than those shown in Table 1 are shown in Table 2.
Here, no. 1 to 3 are examples of the invention using the finishing annealing equipment of the present invention in which the cooling pipe having the double pipe structure shown in FIG. 1 is provided for finishing annealing, using air as a cooling gas, and cooling process The flow rate of the cooling gas flowing between the inner tube and the outer tube in was changed to three levels of 2.5 m / s, 5 m / s, and 10 m / s, respectively. In Table 1, No. 4 is a comparative example using the finish annealing equipment of the prior art shown in FIG.

Figure 0005839177
Figure 0005839177

Figure 0005839177
Figure 0005839177

上記の仕上焼鈍に際しては、コイルの板幅中央部かつコイル半径方向の複数位置(5点)に熱電対を挿入しておき、仕上焼鈍時における各位置の温度変化を測定した。
また、仕上焼鈍を施したコイルは、その後、絶縁被膜の塗布・焼付と形状矯正を兼ねた平坦化焼鈍を施した後、切断して切り板(シート)とした。この際、コイル長さ方向の鋼板形状(耳伸び、中伸び)を非接触のレーザー変位計にて測定し、板幅方向の鋼板高さの変動量が5mm以上ある部分を形状不良部と判定し、その長さを測定した。
また、コイル外周部、中巻部および内周部の切り板からサンプルを採取し、エプスタイン試験で鉄損W17/50を測定してコイル長さ方向の鉄損分布を求め、鉄損の最良値と最悪値の差(ばらつきの大きさ)を求めた。
In the above-described finish annealing, thermocouples were inserted at a plurality of positions (5 points) in the center of the coil width and in the coil radial direction, and the temperature change at each position during the finish annealing was measured.
Moreover, the coil which gave finish annealing was cut | disconnected and cut into a cutting board (sheet | seat), after giving the flattening annealing which combined application | coating / baking of an insulating film, and shape correction after that. At this time, the steel plate shape (ear extension, middle extension) in the coil length direction is measured with a non-contact laser displacement meter, and the portion where the fluctuation amount of the steel plate height in the plate width direction is 5 mm or more is determined as a defective shape portion. The length was measured.
Also, samples are taken from the outer peripheral part, the middle winding part and the inner peripheral part of the coil, and the iron loss W 17/50 is measured by the Epstein test to determine the iron loss distribution in the coil length direction. The difference between the value and the worst value (size of variation) was obtained.

図10は、仕上焼鈍の加熱時に、コイル外周面の温度管理ポイントが900℃に達した時点におけるコイル半径方向の温度分布を、表1のNo.2(発明例)とNo.4の比較例について比較して示したものである。同じく図11は、仕上焼鈍の冷却時に、コイル外周面の温度管理ポイントが800℃まで冷却した時点におけるコイル半径方向の温度分布を、表1のNo.2(発明例)とNo.4の比較例について比較して示したものである。
これらの図から、本発明の仕上焼鈍設備を用いることにより、従来の仕上焼鈍設備と比較して、加熱過程におけるコイル内周面の温度上昇を抑制し、かつ、冷却過程におけるコイル内周面の冷却を促進できていることがわかる。
10 shows the temperature distribution in the coil radial direction at the time when the temperature control point on the outer peripheral surface of the coil reached 900 ° C. during heating in the finish annealing. 2 (invention example) and No. 2 4 shows comparative examples. Similarly, FIG. 11 shows the temperature distribution in the coil radial direction when the temperature control point on the outer peripheral surface of the coil is cooled to 800 ° C. during the cooling of the finish annealing. 2 (invention example) and No. 2 4 shows comparative examples.
From these figures, by using the finish annealing equipment of the present invention, compared with the conventional finish annealing equipment, the temperature rise of the coil inner peripheral surface in the heating process is suppressed, and the coil inner peripheral surface in the cooling process is suppressed. It can be seen that cooling can be promoted.

また、表1には、No.1〜3の発明例と、No.4の比較例の形状不良部の長さの測定結果およびコイル内の鉄損差を併記した。さらに、表1には、No.1〜3の発明例の冷却時間を、No.4の比較例(従来技術)を基準(1.0)として相対値で示した。
この結果から、従来の仕上焼鈍設備を用いたNo.4の比較例では、加熱過程におけるコイル内温度および冷却過程におけるコイル内温度の不均一分布に起因して、形状不良部が長さ200mにわたって発生し、コイル内長さ方向で、鉄損W17/50:0.04W/kgの差が認められた。これに対して、本発明の仕上焼鈍設備を用いた発明例では、形状不良部の長さが100m以下に改善され、しかも、コイル内の鉄損変動も0.02W/kg以下に低減することができている。さらに、冷却ガスの流速を5m/s以上とした場合には、形状不良部の長さが15mと大幅に改善され、しかも、コイル内の鉄損変動もほぼゼロまで解消されている。しかも、冷却ガスの流速を5m/s以上とすることで、冷却時間を約1/2まで短縮できていることがわかる。
In Table 1, No. 1 to 3 and No. 1 The measurement result of the length of the shape defect part of 4 comparative examples and the iron loss difference in a coil were written together. Further, in Table 1, No. The cooling times of the inventive examples 1 to 3 are The comparative example (prior art) of 4 was shown as a relative value with the reference (1.0).
From this result, No. 1 using the conventional finish annealing equipment. In the comparative example 4, due to the uneven distribution of the temperature in the coil in the heating process and the temperature in the coil in the cooling process, a defective shape portion occurs over a length of 200 m, and the iron loss W 17 in the length direction in the coil. / 50 : A difference of 0.04 W / kg was observed. On the other hand, in the invention example using the finish annealing equipment of the present invention, the length of the defective shape portion is improved to 100 m or less, and the iron loss fluctuation in the coil is also reduced to 0.02 W / kg or less. Is done. Furthermore, when the flow rate of the cooling gas is set to 5 m / s or more, the length of the defective shape portion is greatly improved to 15 m, and the iron loss fluctuation in the coil is eliminated to almost zero. Moreover, it can be seen that the cooling time can be reduced to about ½ by setting the flow rate of the cooling gas to 5 m / s or more.

本発明の技術は、方向性電磁鋼板の仕上焼鈍設備に限定されるものではなく、例えば、一般的な冷延鋼板や熱延鋼板の焼鈍に用いるバッチ式の箱型焼鈍設備にも適用することができる。   The technology of the present invention is not limited to finish annealing equipment for grain-oriented electrical steel sheets, but may be applied to, for example, batch-type box annealing equipment used for annealing general cold-rolled steel sheets and hot-rolled steel sheets. Can do.

1:鋼板コイル
2:コイル置台
3:インナーケース(インナーカバー)
4:焼鈍炉の加熱炉
5:加熱バーナー
6:冷却ノズル
7:冷却ガス
8:インナーケースの円筒状凹部
9:冷却管
10:冷却管の外管
11:冷却管の内管
D1:コイル内径
D2:冷却管の外管径
1: Steel plate coil 2: Coil mount 3: Inner case (inner cover)
4: Heating furnace of annealing furnace 5: Heating burner 6: Cooling nozzle 7: Cooling gas 8: Cylindrical recess of inner case 9: Cooling pipe 10: Outer pipe of cooling pipe 11: Inner pipe of cooling pipe D1: Coil inner diameter D2 : Outer diameter of cooling pipe

Claims (5)

方向性電磁鋼板の仕上焼鈍に用いるバッチ式の箱型焼鈍設備であって、コイル置台上にアップエンドに載置されたコイル内径部に挿入される、上方を閉じた外管とその内部に円筒状の内管を有する2重管構造で、外管外径がコイル内径の0.3倍以上であり、かつ、外管外周面とコイル内周面とが50mm以上離間している冷却管を立設してなることを特徴とする仕上焼鈍設備。 This is a batch type box-type annealing facility used for finish annealing of grain-oriented electrical steel sheets, which is inserted into the inner diameter of the coil placed on the coil end on the coil end, and an outer tube with a closed top and a cylinder inside it. A cooling pipe having a double pipe structure having a cylindrical inner pipe , the outer diameter of the outer pipe being 0.3 or more times the inner diameter of the coil, and the outer circumference of the outer pipe and the inner circumference of the coil being separated by 50 mm or more. Finishing annealing equipment characterized by standing. 上記冷却管は、内管の内側断面積が、外管の内側断面積の0.3〜0.7倍であることを特徴とする請求項に記載の仕上焼鈍設備。 The finish annealing equipment according to claim 1 , wherein the cooling pipe has an inner cross-sectional area of the inner pipe of 0.3 to 0.7 times the inner cross-sectional area of the outer pipe. 請求項1または2に記載の仕上焼鈍設備を用いる方向性電磁鋼板の仕上焼鈍方法であって、上記2重管構造の冷却管内に冷却ガスを流しながら仕上焼鈍することを特徴とする方向性電磁鋼板の仕上焼鈍方法。 A direction annealing method for a grain-oriented electrical steel sheet using the finish annealing facility according to claim 1 or 2 , wherein the finish annealing is performed while flowing a cooling gas into the cooling pipe having the double pipe structure. Finish annealing method for steel sheet. 上記冷却ガスを、内管下方から冷却管内に導入し、外管と内管の間を上方から下方に向かって排出する、あるいは、外管と内管の間の下方から冷却管内に導入し、内管の上方から下方に向かって排出することを特徴とする請求項に記載の方向性電磁鋼板の仕上焼鈍方法。 The cooling gas is introduced into the cooling pipe from the lower side of the inner pipe and discharged between the outer pipe and the inner pipe from the upper side to the lower side, or is introduced into the cooling pipe from the lower side between the outer pipe and the inner pipe, 4. A method for finishing annealing a grain-oriented electrical steel sheet according to claim 3 , wherein the discharge is performed from the upper side to the lower side of the inner pipe. 上記内管と外管の間の冷却ガスの流速を5m/s以上とすることを特徴とする請求項3または4に記載の方向性電磁鋼板の仕上焼鈍方法。 The method of finish annealing a grain-oriented electrical steel sheet according to claim 3 or 4 , wherein a flow rate of the cooling gas between the inner pipe and the outer pipe is 5 m / s or more.
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