JPH0627201Y2 - Core bar for piercing and rolling machine - Google Patents

Description

【考案の詳細な説明】 （産業上の利用分野） 本考案は継目無鋼管製造時の穿孔圧延において使用する
浮動式芯金に関し、特に穿孔完了時に芯金自体が芯金内
部に生じた圧力で、前方へ飛ばされない芯金に関する。[Detailed Description of the Invention] (Industrial field of application) The present invention relates to a floating cored bar used in piercing and rolling when manufacturing seamless steel pipes. , About the core metal that is not blown forward.

（従来の技術） 継目無鋼管の圧延による製造には先ず穿孔圧延を行なう
が、この時用いる穿孔用芯金を、保持用マンドレルバー
先端へ取り付ける方法としては、一般に固定式と浮動式
の２つの方式がある。固定式はマンドレルレバーに、ね
じ込みその他の手段でしっかり固定して取りつけられ、
殆どの場合、内部が水冷されていて１個の芯金で連続し
て何本も穿孔できる利点があるが、設備コスト、メンテ
ナンスコスト共に高く、更に、製品に偏肉が起き易いな
どの不利な点もある。これに対し本考案で対象とする浮
動式は、第３図の平面断面図に示したとおり、芯金(1)
を、マンドレル(3)の先端に固着したバーキャップ(2)の
先端穿孔(2′)に、ゆるくはめ込んだだけの状態で穿孔
するので、１本穿孔する毎に取り替えねばならず、作業
コストがかかるが水冷はしてない（出来ない）ので設備
コストは安く、且つ、穿孔中マンドレルによる半径方向
の拘束が少ないので、マンドレルの芯出しが多少狂って
いても偏肉が起きにくく、また、自転し得るので、製品
内面の性状にも好ましいという大きなメリットがある。(Prior Art) When manufacturing a seamless steel pipe by rolling, piercing and rolling are first performed. Generally, there are two methods for attaching the core metal for piercing used to the tip of the holding mandrel bar: a fixed type and a floating type. There is a method. The fixed type can be fixed to the mandrel lever by screwing or other means, and attached.
In most cases, the inside is water-cooled and there is an advantage that many cores can be continuously drilled with one core metal, but both equipment cost and maintenance cost are high, and there are disadvantages such as uneven thickness of products. There are also points. On the other hand, the floating type, which is the object of the present invention, has the core metal (1) as shown in the plan sectional view of FIG.
Is to be inserted into the tip perforation (2 ') of the bar cap (2) fixed to the tip of the mandrel (3) just by loosely fitting it, so it must be replaced every time it is perforated, and the work cost is reduced. Although it is not water-cooled (cannot be done), the equipment cost is low, and since there is little radial restraint by the mandrel during drilling, even if the mandrel is slightly misaligned, uneven thickness is less likely to occur and rotation is not possible. Therefore, there is a great merit that the property of the inner surface of the product is also preferable.

しかし作業コストはかかり、中でも穿孔が完了して、マ
ンドレルが後退（圧延材の進む方向）した後、回転して
いるロール(4)の間の、下ガイドシュー(5)の上に残され
る芯金を、圧延機の製品出側からハッカー（約１．５ｍ
の棒の先を少し曲げたもの）の先を芯金の穴に突込んで
引き寄せ、持ち上げ、冷却槽に入れる作業は危険で、且
つ高熱重筋作業である。なお、第４図 第３図のＡ−Ａ
断面図で、穿孔圧延中のロール（４）、芯金（１）、ガ
イドシュー（５）および素管（Ｗ）の関係を示す。However, there is a cost involved in the work, and in particular, the core left on the lower guide shoe (5) between the rotating rolls (4) after boring is completed and the mandrel retracts (the direction in which the rolled material advances). The hacker (about 1.5m) from the product output side of the rolling mill
It is dangerous to put the end of the rod (with the tip of the rod slightly bent) into the hole of the core bar, pull it up, and put it in the cooling tank. Incidentally, AA in FIG. 4 and FIG.
The cross-sectional view shows the relationship between the roll (4), the core metal (1), the guide shoe (5), and the raw pipe (W) during piercing and rolling.

（解決すべき問題点） ところが、この作業を更に厄介にする現象が時々発生す
る。即ち、芯金は通常ならば穿孔完了と同時にシエルか
ら抜けてその場に落ちるのであるが、何かの原因で２０
〜３０cmも先の方まで飛んで転るという異常飛びが往々
にして発生する。これが起こると、作業員は回転するロ
ールの間に身を乗り入れるようにしてハッカーを扱わね
ばならず、それでも届かない場合は反対側（材料入り
側）にまわって処理しなければならないが、反対側にま
わるには、ロールの回転を止めねばならず、生産性を著
しく阻害することになる。このような現象は穿孔圧延の
サイズによっては３０％近くも発生することがあり、こ
れが解決の要に迫られていた。(Problems to be solved) However, a phenomenon sometimes occurs that makes this work more troublesome. In other words, the core metal normally comes out of the shell at the same time as the completion of drilling and falls there, but for some reason
Abnormal jumps often occur up to 30 cm away and roll. When this happens, the worker must treat the hacker as a roll between rolling rolls, and if it still does not reach, the other side (material side) must be dealt with, but the other side. In order to turn around, the rotation of the roll has to be stopped, which significantly impairs the productivity. Such a phenomenon may occur as much as 30% depending on the size of the piercing and rolling, and this is the key to the solution.

（解決の手段および作用） 本考案は上記課題の解決の為になされたものでその要旨
は請求の範囲に記載のとおりの芯金であって、第１図お
よび第２図に実施の１例を示すとおり、要するに芯金の
後端面に圧力逃がしの溝（６）をつけたものである。即
ち、浮動芯金は尻に穴をあけた砲弾と同じで、これを第
３図に示すとおり、マンドレルの先の、穴よりも少し細
い円錐台形突起(2′)に単に挿し込んだだけで穿孔を行
うのであるが、何らかの条件のときに芯金の端面と突起
の基面とが気密に密着したまま最後まで穿孔が行なわ
れ、穴と突起の隙間に入っていた冷却水が高温の水蒸気
となり、内部に高圧を発生させ、これが穿孔完了と同時
に芯金を前方へ飛ばすものと推定し、そして実際に本考
案の芯金を作り使ってみることにより、それが正しいこ
とを確認したものである。(Means and Solution for Solving) The present invention has been made to solve the above problems, and its gist is a cored bar as set forth in the claims, and an example of the embodiment shown in FIG. 1 and FIG. In short, the pressure relief groove (6) is formed on the rear end surface of the core metal. That is, the floating core is the same as a shell with a hole in the butt, and as shown in Fig. 3, it is simply inserted into the frustoconical projection (2 ') slightly thinner than the hole at the tip of the mandrel. Drilling is performed, but under some conditions, the end surface of the core metal and the base surface of the protrusions are airtightly adhered to the end, and the cooling water contained in the gap between the hole and the protrusion is hot steam. Therefore, it is assumed that high pressure is generated inside, and that this causes the core bar to fly forward as soon as the drilling is completed, and by actually making and using the core bar of the present invention, it was confirmed that it was correct. is there.

（実施例） 本考案の芯金をアッセルミルの穿孔圧延の全てに使用し
ているが、その一実施例として、直径７５mmの芯金の場
合を次に述べる。芯金のサイズは外径７５mm、長さ２０
６mm、穴の基面直径３４mm、深さ９０mmの部分の直径２
９mm深さ全長１３０mm、重さ４．１kgで、これの後端環
状面に幅、深さ共に５mmの溝を半径方向に２本、２本が
ほぼ一直線になるようにつけた。一方、マンドレルの方
の突起は基部径が３２mm先端径が２７mm、長さは６５mm
で、穴と突起の間には２mmの余裕がある。これを用いて
軸受鋼（ＪＩＳ ＳＵＪ２）の直径１００mm、長さ2.５
ｍのビレットを、外径１０６mm、内径７７mm、長さ約５
ｍの素管に多数本穿孔圧延した。その結果、従来このサ
イズは、その他の特定し得ない条件が重なったと思われ
るロットでは２０〜３０％も発生していたが、実施例の
芯金を使用した場合はこれが２〜３％の発生率に落ち着
いている。また、他のサイズについても、従来、主とし
て細物（芯金径で５０〜１００mm）を中心に５〜１０％
程度発生していたのが、同様に２〜３％に下がってい
る。(Example) The core metal of the present invention is used for all the piercing and rolling of an Assel mill. As an example, a core metal having a diameter of 75 mm will be described below. The core metal has an outer diameter of 75 mm and a length of 20.
6mm, hole base diameter 34mm, depth 90mm part diameter 2
The total length is 9 mm, the total length is 130 mm, and the weight is 4.1 kg. Two grooves, each having a width and a depth of 5 mm, are formed on the rear end annular surface of the two grooves in a radial direction so that the grooves are substantially in a straight line. On the other hand, the protrusion on the mandrel has a base diameter of 32 mm, a tip diameter of 27 mm, and a length of 65 mm.
There is a 2mm margin between the hole and the protrusion. Using this, bearing steel (JIS SUJ2) has a diameter of 100 mm and a length of 2.5
m billet, outer diameter 106mm, inner diameter 77mm, length about 5
A large number of m pipes were perforated and rolled. As a result, conventionally, this size was 20 to 30% in the lot which seems to be overlapped with other unspecified conditions, but when the core metal of the example is used, this is 2 to 3%. The rate has settled down. Also, for other sizes, 5 to 10% has been used mainly for fine products (core diameter: 50 to 100 mm).
Although it has occurred to some extent, it has fallen to 2-3%.

（効果） 本考案の芯金の採用により、前記したように特定サイズ
では、異常飛びの発生率が１０〜３０％発生していたの
が、全て２〜３％に低減し、生産性と、安全性が飛躍的
に向上した。(Effect) By adopting the cored bar of the present invention, the occurrence rate of abnormal jump was 10 to 30% in the specific size as described above, but it was reduced to 2 to 3% in all, and productivity and The safety has improved dramatically.

【図面の簡単な説明】[Brief description of drawings]

第１図は本考案の実施の１例の断面図、第２図は第１図
のＡ−Ａ矢視図、第３図は浮動式芯金による穿孔圧延中
の平面断面図、第４図は第３図のＡ−Ａ断面図である。FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a sectional view taken along the line AA of FIG. 1, FIG. 3 is a plan sectional view during piercing and rolling with a floating core bar, and FIG. FIG. 4 is a sectional view taken along line AA of FIG.

Claims (1)

【実用新案登録請求の範囲】[Scope of utility model registration request] 【請求項１】継目無鋼管製造用の穿孔圧延機の浮動式芯
金において、浮動はめ合わせ用ホールがあけられた芯金
後端の環状端面に、内面から外面に通ずる１本又は複数
本のガス抜き溝をつけたことを特徴とする穿孔圧延機用
芯金1. A floating cored bar of a piercing and rolling mill for producing a seamless steel pipe, wherein one or a plurality of ones extending from an inner surface to an outer surface are provided on an annular end surface of a rear end of the cored bar having a hole for floating fitting. Core bar for piercing and rolling mill characterized by having a degassing groove