JP3579799B2

JP3579799B2 - Steel step cooling method and apparatus

Info

Publication number: JP3579799B2
Application number: JP18074994A
Authority: JP
Inventors: 重信濱中
Original assignee: HAMANAKA NUT MFG. CO.,LTD.
Current assignee: HAMANAKA NUT MFG. CO.,LTD.
Priority date: 1994-07-08
Filing date: 1994-07-08
Publication date: 2004-10-20
Anticipated expiration: 2019-10-20
Also published as: JPH0820816A

Description

【０００１】
【産業上の利用分野】
この発明は、鋼の段階冷却方法及びその装置に関し、特に段階冷却を連続して効率よく行えるようにした方法及び装置に関する。
【０００２】
【従来の技術】
機械部品、例えばボルトやナットを製造する場合、素形材を鍛造するとともに、焼入れ焼戻しによって機械的性質を確保し、ねじ立てを行った後、洗浄して最終的な成品とするのが一般的である。
【０００３】
ところで、鋼を焼入れする場合、単に水焼入れを行うと（図２の冷却特性ａーｄ参照）焼き割れが懸念される一方、油焼入れを行うと組成によっては連続冷却変態線図が全体として短時間側に移行し、組織中にパーライトが生成され（図２の冷却特性ｃ参照）、焼入れが不十分となることがある。
【０００４】
これに対し、従来より引上げ焼入れ等の段階冷却が提案されている。例えば、引上げ焼入れではオーステナイト状態に加熱した鋼を水中でマルテンサイト変態開始点Ｍ_ｓ直上の温度まで過冷し、適当な時間が経過したところで鋼を水中から引上げ、油冷や空冷によってマルテンサイト変態を開始させ、焼き割れを起こすことなく焼入れを行うことができる。
【０００５】
【発明が解決しようとする課題】
しかし、従来の引上げ焼入れでは冷却の途中で鋼を一旦水中から引上げて冷却速度を変化させる必要があり、油冷の場合には冷却槽が２槽となって装置が大型化し、又空冷の場合には冷却が不均一になるおそれがある。
【０００６】
この発明は、かかる問題点に鑑み、装置の大型化や冷却の不均一化を招来することなく、段階冷却を連続して効率よく行えるようにした鋼の段階冷却方法を提供することを課題とする。
【０００７】
【課題を解決するための手段】
そこで、本発明に係る鋼の段階冷却方法は、鋼を異なる冷却速度でもって段階冷却するにあたり、比重の大きい第１冷却液と、第１冷却液と相溶せずかつ異なる冷却能を有する比重の小さい第２冷却液とを用い、第１冷却液のみの第１冷却領域と第１、第２の冷却液が二層をなす第２冷却領域とを下層の第１冷却液部分で連続させ、加熱した鋼を第１又は第２冷却領域に上方から下方に向けて通過させた後、第２又は第１冷却領域側に移行させて引き上げ、急冷・緩冷又は緩冷・急冷するようにしたことを特徴とする。
【０００８】
本発明に係る段階冷却は鋼の焼入れに適用すればその効果が大きいが、徐冷にも適用できる。通常、鋼を徐冷する場合、所定温度、例えば室温までは緩冷する必要があるが、その後は急冷してもそれほど問題が生じない場合がある。そこで、かかる場合には加熱した鋼を第２冷却領域側にゆっくりと送り込んで冷却能の小さい第２冷却液で所定温度まで緩冷した後、冷却能の大きい第１冷却液で急冷しつつ引き上げると、冷却能の小さい冷却液のみで徐冷する場合に比して短い時間で徐冷ができる。
【０００９】
鋼の焼入れの場合、オーステナイト状態の鋼を第１冷却領域に投入して第２冷却領域側から引上げ、冷却能の大きい第１冷却液でマルテンサイト変態開始温度Ｍ_ｓ直上まで急冷した後、冷却能の小さい第２冷却液で緩冷してマルテンサイト変態を行わせる。
【００１０】
第１、第２の冷却液は相互に冷却能及び比重が異なるとともに相溶しないものであればよく、例えば第１冷却液として水、第２冷却液として油を用いることができる。
【００１１】
本発明によれば、冷却液槽が仕切板で下層連通部を残して前後に２槽に分割され、該仕切板によって分割される第１槽には比重の大きい第１冷却液が貯留され、第２槽には比重の大きい第１冷却液と第１冷却液に相溶せずかつ異なる冷却能を有する比重の小さい第２冷却液とが上下二層に貯留され、第１槽及び第２槽には冷却液槽の側壁上方からほぼ仕切板の下方に向けて第１、第２搬送手段が傾斜してかつ第２槽下層域で相互に鋼を受渡し可能に設けられている鋼材の段階冷却装置を提供することができる。
【００１２】
搬送手段は傾斜され両者間で被冷却体を受渡しできればベルトコンベア同士の組合せ、ベルトコンベアとやシュータとの組合せ等を採用すればよい。例えば、鋼の焼入れの場合にはオーステナイト状態の鋼を第１冷却領域で急冷する必要があるので、第１搬送手段をシュータ、第２搬送手段をベルトコンベアとするのがよい。
【００１３】
【作用及び発明の効果】
本発明によれば、第１冷却領域に冷却能の大きい第１冷却液を貯留し、第２冷却領域には下層に第１冷却液を、上層に冷却能の小さい第２の冷却液を貯留し、鋼を第１冷却液から第２冷却液、又は第２冷却液から第１冷却液に送って急冷・緩冷又は緩冷・急冷を行うようにしたので、段階冷却を連続して行うことができ、作業効率を大幅にアップでき、作業時間を短縮できる。しかも、油冷の場合のような大型の装置を必要とせず、又空冷に比して均一な冷却が可能となる。
【００１４】
【実施例】
以下、本発明の実施例を図について説明する。図１は本発明の一実施例による鋼の段階冷却装置を示す。図において、冷却液槽１はほぼ立方体状をなして上面が開放され、該冷却液槽１内にはほぼ中央に仕切板７が取付けられて下方連通部を残して上方部が２槽に仕切られ、該仕切板７の一側方（図１の左側方）は第１槽、他側方は第２槽となっている。
【００１５】
第１槽には水（第１冷却液）２が貯留されて第１冷却領域１０、第２槽には下方に水２が、上方に比重の小さい油（第２冷却液）３が仕切板７の下端縁近傍を境界として上下二層に貯留されて第２冷却領域１１が構成され、第１、第２冷却領域１０、１１は仕切板７の下方で連通されている。
【００１６】
また、冷却液槽１内には第１冷却領域１０側にシュータ６が壁面上端から中央下方に向けて傾斜して設けられ、第２冷却領域１１にはベルトコンベア５が壁面上端から中央下方に向けて傾斜して設けられ、シュータ６の下端部は第２冷却領域１１、即ち第２槽下層域でベルトコンベア５に鋼製部品Ｗを受渡しできるように設定されている。なお、ベルトコンベア５には鋼製部品Ｗを保持するための突起を形成しておくのがよい。
【００１７】
鋼製部品Ｗを段階焼入れする場合、鋼製部品Ｗを加熱炉でオーステナイト状態まで加熱し、これをシュータ６によって第１冷却領域１０側の水中に投入すると、鋼製部品Ｗは第１冷却領域１０内のシュータ６を下方に滑り、さらに第２冷却領域１１側のベルトコンベア５に受渡され、ベルトコンベア５によって第２冷却領域１１内をゆっくりと引上げられ、冷却液層１から送り出される。
【００１８】
すると、鋼製部品Ｗは第１、第２冷却領域１０、１１の水中移動中にマルテンサイト変態開始温度Ｍ_ｓ直上の温度まで急冷され（図２の冷却特性ａ参照）、第２冷却領域１１の油中をゆっくり引き上げられる時に緩冷され（図２の冷却特性ｂ参照）、マルテンサイト変態が開始する。
【００１９】
従って、鋼製部品Ｗの段階焼入れを１つの冷却液槽１によって連続して行うことができ、従来の引上げ焼入れに比して作業時間を短縮できる。
【００２０】
図３は本発明の他の実施例による鋼の段階冷却装置を示す。本実施例ではシュート６に代えてベルトコンベア８が用いられ、加熱した鋼製部品Ｗを第２冷却領域１１に上方から下方に向けて通過させた後、第１冷却領域１０側に移行させて引き上げ、緩冷・急冷できるようにしている。なお、図中、図１と同一符号は同一又は相当部分を示す。
【００２１】
本実施例では加熱した鋼製部品Ｗを徐冷する場合に短時間で効率よく行える。
【図面の簡単な説明】
【図１】本発明の一実施例による鋼の段階冷却装置を示す概略側面構成図である。
【図２】鋼の段階焼入れを説明するための連続冷却変態線図である。
【図３】本発明の他の実施例を示す概略側面構成図である。
【符号の説明】
１冷却液槽
１０第１冷却液槽
１１第２冷却領域
２水（第１冷却液）
３油（第２冷却液）
５ベルトコンベア（第２搬送手段）
６シュータ（第１搬送手段）
７仕切板
８ベルトコンベア（第１搬送手段）
Ｗ鋼製部品[0001]
[Industrial applications]
The present invention relates to a method and an apparatus for cooling stepwise steel, and more particularly, to a method and an apparatus for continuously and efficiently performing stepwise cooling.
[0002]
[Prior art]
When manufacturing machine parts, for example, bolts and nuts, it is common practice to forge the shaped material, secure the mechanical properties by quenching and tempering, tapped, wash, and finalize the finished product It is.
[0003]
By the way, in the case of quenching steel, if water quenching is simply performed (see cooling characteristics ad in FIG. 2), quenching cracking is a concern, but if oil quenching is performed, the continuous cooling transformation diagram is short as a whole depending on the composition. It shifts to the time side, pearlite is generated in the structure (see cooling characteristic c in FIG. 2), and quenching may be insufficient.
[0004]
On the other hand, step cooling such as pull-up quenching has been conventionally proposed. For example, subcooled in pulling hardened steel heated to austenite state in water to a temperature just above the martensite transformation start point M _s, raising the steel from water where appropriate time has elapsed, the martensitic transformation by oil cooling and air cooling Once started, quenching can be performed without causing quenching cracks.
[0005]
[Problems to be solved by the invention]
However, in the conventional pull-up quenching, it is necessary to change the cooling rate by pulling the steel once from the water during cooling, and in the case of oil cooling, the cooling tank becomes two tanks, the equipment becomes large, and in the case of air cooling, May have uneven cooling.
[0006]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a step cooling method for steel capable of performing step cooling continuously and efficiently without causing an increase in the size of the apparatus and uneven cooling. I do.
[0007]
[Means for Solving the Problems]
Therefore, in the step cooling method of steel according to the present invention, when the steel is step-cooled at different cooling rates, a first cooling liquid having a large specific gravity and a specific gravity having a different cooling capacity that are not compatible with the first cooling liquid. The second cooling liquid having a small size is used to make the first cooling area containing only the first cooling liquid and the second cooling area in which the first and second cooling liquids form two layers continuous at the lower first cooling liquid portion. After passing the heated steel from the upper side to the lower side in the first or second cooling area, the steel is shifted to the second or first cooling area side and pulled up, and quenched / cooled or cooled / quenched. It is characterized by having done.
[0008]
The step cooling according to the present invention has a great effect if applied to quenching of steel, but can also be applied to slow cooling. Normally, when gradually cooling steel, it is necessary to slowly cool it to a predetermined temperature, for example, room temperature. Therefore, in such a case, the heated steel is slowly fed into the second cooling area side, slowly cooled to a predetermined temperature with a second cooling liquid having a small cooling capacity, and then pulled up while being rapidly cooled with a first cooling liquid having a large cooling capacity. Thus, slow cooling can be performed in a shorter time as compared with the case where slow cooling is performed only with a cooling liquid having a small cooling capacity.
[0009]
For quenching of steel, raising the second cooling region side to put the austenitic state steel the first cooling region, it was quenched to the martensitic transformation start temperature M _s right above the first coolant large cooling capacity, cooling The martensite transformation is performed by slow cooling with a second cooling liquid having a small capacity.
[0010]
The first and second cooling liquids need only have different cooling capacities and specific gravities and are incompatible with each other. For example, water can be used as the first cooling liquid and oil can be used as the second cooling liquid.
[0011]
According to the present invention, the cooling liquid tank is divided into two tanks before and after leaving a lower layer communication part by a partition plate, and the first cooling liquid having a large specific gravity is stored in the first tank divided by the partition plate, In the second tank, a first cooling liquid having a large specific gravity and a second cooling liquid having a low specific gravity that is incompatible with the first cooling liquid and have a different cooling capacity are stored in upper and lower two layers. A stage of a steel material in which the first and second conveying means are inclined from the upper side wall of the cooling liquid tank to substantially below the partition plate, and are capable of mutually passing steel in the lower region of the second tank. A cooling device can be provided.
[0012]
If the conveying means is inclined and the object to be cooled can be transferred between them, a combination of belt conveyors, a combination of a belt conveyor and a shooter, or the like may be adopted. For example, in the case of quenching steel, it is necessary to rapidly cool the austenitic steel in the first cooling region. Therefore, it is preferable that the first conveying means is a shooter and the second conveying means is a belt conveyor.
[0013]
[Action and effect of the invention]
According to the present invention, a first cooling liquid having a large cooling capacity is stored in a first cooling area, a first cooling liquid is stored in a lower layer in a second cooling area, and a second cooling liquid having a small cooling capacity is stored in an upper layer. Then, the steel is sent from the first cooling liquid to the second cooling liquid or from the second cooling liquid to the first cooling liquid to perform rapid cooling / slow cooling or slow cooling / rapid cooling, so that the step cooling is continuously performed. Work efficiency can be greatly increased, and work time can be reduced. In addition, a large-sized device unlike oil cooling is not required, and uniform cooling can be achieved as compared with air cooling.
[0014]
【Example】
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a step cooling apparatus for steel according to an embodiment of the present invention. In the figure, a cooling liquid tank 1 has a substantially cubic shape and an upper surface is opened, and a partition plate 7 is attached in the center of the cooling liquid tank 1 so that an upper part is divided into two tanks while leaving a lower communicating part. One side (the left side in FIG. 1) of the partition plate 7 is a first tank, and the other side is a second tank.
[0015]
Water (first cooling liquid) 2 is stored in the first tank, the first cooling area 10, water 2 is downward in the second tank, and oil (second cooling liquid) 3 having a low specific gravity is in the upper part. The second cooling region 11 is configured by being stored in upper and lower two layers with the vicinity of the lower edge of the boundary 7 as a boundary, and the first and second cooling regions 10 and 11 are communicated below the partition plate 7.
[0016]
In the cooling liquid tank 1, a shooter 6 is provided on the first cooling region 10 side from the upper end of the wall toward the center downward, and the belt conveyor 5 is provided in the second cooling region 11 from the upper end of the wall toward the lower center. The lower end of the shooter 6 is set so that the steel part W can be transferred to the belt conveyor 5 in the second cooling area 11, that is, the lower area of the second tank. Note that a projection for holding the steel part W is preferably formed on the belt conveyor 5.
[0017]
When the steel part W is to be gradually quenched, the steel part W is heated to an austenitic state by a heating furnace and is put into the water on the first cooling area 10 side by the shooter 6. The chute 6 slides down in the chute 10, is further transferred to the belt conveyor 5 on the second cooling area 11 side, is slowly pulled up in the second cooling area 11 by the belt conveyor 5, and is sent out from the coolant layer 1.
[0018]
Then, steel parts W is first, while water movement in the second cooling regions 10 and 11 are quenched to a temperature just above the martensite transformation start temperature M _s (see cooling characteristic a in FIG. 2), the second cooling region 11 Is slowly cooled (see cooling characteristic b in FIG. 2) when the oil is slowly pulled up, and martensitic transformation starts.
[0019]
Therefore, the step quenching of the steel part W can be performed continuously by one cooling liquid tank 1, and the operation time can be reduced as compared with the conventional pull-up quench.
[0020]
FIG. 3 shows a step cooling apparatus for steel according to another embodiment of the present invention. In this embodiment, a belt conveyor 8 is used in place of the chute 6, and after the heated steel part W is passed through the second cooling area 11 from above to below, the steel part W is moved to the first cooling area 10 side. It is raised so that it can be cooled slowly and rapidly. In the drawing, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts.
[0021]
In this embodiment, when the heated steel part W is gradually cooled, it can be efficiently performed in a short time.
[Brief description of the drawings]
FIG. 1 is a schematic side view showing a step cooling apparatus for steel according to an embodiment of the present invention.
FIG. 2 is a continuous cooling transformation diagram for explaining stepwise quenching of steel.
FIG. 3 is a schematic side view showing another embodiment of the present invention.
[Explanation of symbols]
Reference Signs List 1 cooling liquid tank 10 first cooling liquid tank 11 second cooling area 2 water (first cooling liquid)
3 oil (second cooling liquid)
5. Belt conveyor (second transport means)
6. Shooter (first transport means)
7 Partition plate 8 Belt conveyor (first transport means)
W steel parts

Claims

In stepwise cooling steel at different cooling rates,
A first cooling liquid having a large specific gravity and a second cooling liquid having a small specific gravity that is incompatible with the first cooling liquid and have a different cooling capacity are used, and the first cooling region 10 having only the first cooling liquid and the first cooling liquid are used. The second cooling liquid is made continuous with the second cooling region 11 forming a two-layer structure in the lower first liquid cooling portion,
After passing the heated steel W through the first or second cooling region 10, 11 from above to below, the steel W is moved to the second or first cooling region 11, 10 side and pulled up, and quenched / cooled or cooled slowly. A step cooling method for steel, wherein the steel is cooled and quenched.

2. The method according to claim 1, wherein water 2 is used as the first cooling liquid and oil 3 is used as the second cooling liquid.

Pulling the second cooling region 11 side by introducing the steel W austenitic state to the first cooling region 10, after rapidly cooled to just above the martensitic transformation start temperature M _s by a first coolant 2, loose by the second coolant 3 3. The heat treatment method for steel according to claim 2, wherein the steel is cooled to perform a martensitic transformation.

The coolant tank 1 is divided into two tanks before and after by a partition plate 7 except for a lower layer communication portion. The first tank divided by the partition plate 7 stores a first coolant having a large specific gravity. The first cooling liquid having a large specific gravity and the second cooling liquid having a small specific gravity that is incompatible with the first cooling liquid and have a different cooling capacity are stored in upper and lower two layers. The first and second conveying means are inclined from the upper side wall of the cooling liquid tank 1 to the lower side of the partition plate 7 and are provided so as to be able to transfer the steel W mutually in the lower region of the second tank. Steel stage cooling device.

The step cooling device for steel according to claim 5, wherein the first conveying means is the shooter 6, the second conveying means is the belt conveyor 5, and the step quenching of the steel W is enabled.