JP3825423B2 - Thick metal cylinder or cylindrical container hot press forming method and bottomed container manufacturing apparatus - Google Patents

Description

【００７８】
ここで、キャスクやキャニスタ等の放射性物質格納容器に使用するために、成形した底付容器の外側および内側を切削加工する例について説明する。第９図は、熱間拡張成形した底付容器の外側を切削加工する装置を示す概略図である。底付容器１はローラを備えた回転支持台１５４上に載せられており、周方向へ自在に回転できる。底付容器１の外側には固定テーブル１４１が設けられており、この固定テーブル１４１上を底付容器１の軸方向に摺動する可動テーブル１４２が備えられている。この可動テーブル１４２には切削用のバイト１６０が取付けられており、このバイト１６０によって底付容器１の外周を切削加工する。
【００７９】
回転支持台１５４に取付けられているローラ１６１はモータ１６２と連結されている。モータ１６１の回転はローラ１６１を介して底付容器１に伝わり、底付容器１を回転させる。モータ１６１が回転して底付容器１が図の矢印方向に回転を始めたら、固定テーブル１４１の端部に設けたサーボモータ１５７とボールねじ１５８によって可動テーブル１４２を底付容器１の軸方向へ移動させ、可動テーブル１４２に取付けられたバイト１６０によって底付容器１の外周を切削する。また、フェースミル等によって外周を削り平面を設ければ、軸方向に垂直な断面が円形のみならず、多角形の底付容器も成形できる。
【００８０】
つぎに、成形した底付容器の内側を切削加工する例について説明する。第１０図は底付容器の内側を加工する装置を示す概略図である。この加工装置１４０は、胴本体１０１内を貫通するとともに底付容器１の内部に載置固定される固定テーブル１４１と、固定テーブル１４１上を軸方向に摺動する可動テーブル１４２と、可動テーブル１４２上にて位置決め固定されているサドル１４３と、サドル１４３上に設けられスピンドル１４４および駆動モータ１４５からなるスピンドルユニット１４６と、スピンドル軸に設けたフェースミル１４７とから構成されている。また、スピンドルユニット１４６上には、底付容器１の内形状に従って当接部を成形した反力受け１４８が設けられている。この反力受け１４８は、着脱自在であって蟻溝（図示省略）に沿って図中矢印方向にスライドする。また、反力受け１４８は、スピンドルユニット１４６に対するクランプ装置１４９を有しており、所定位置にて固定することができる。
【００８１】
さらに、固定テーブル１４１の下部溝内には、複数のクランプ装置１５０が取付けられている。このクランプ装置１５０は、油圧シリンダ１５１と、油圧シリンダ１５１の軸に設けたくさび状の移動ブロック１５２と、当該移動ブロック１５２と傾斜面で当接する固定ブロック１５３とから構成されており、図中斜線部側を固定テーブル１４１の溝内面に取付けるようにする。
【００８２】
油圧シリンダ１５１の軸を駆動すると、移動ブロック１５２が固定ブロック１５３に当接し、くさびの効果により移動ブロック１５２が多少下方に移動する（図中の点線で示す）。これにより、移動ブロック１５２の下面がキャビティ１０２内面に押し当てられるから、固定テーブル１４１を底付容器１の内側で固定することができる。
【００８３】
また、底付容器１はローラからなる回転支持台１５４上に載せられており、径方向に回転自在となる。また、スピンドルユニット１４６とサドル１４３との間にスペーサ１５５を取付けることにより、固定テーブル１４１上の工具１４７の高さを調整することができる。スペーサ１５５の厚さは、上記バスケットを構成する角パイプの一辺の寸法と同じである。サドル１４３は、可動テーブル１４２に設けたサーボモータ１５６を回転させることにより胴本体１０１の径方向に移動する。可動テーブル１４２は、固定テーブル１４１の端部に設けたサーボモータ１５７とボールネジ１５８により移動制御される。なお、加工が進むにつれて底付容器１内側の形状が変わるので、反力受け１４８やクランプ装置１５０の移動ブロック１５２を適当な形状のものに変更する必要がある。
【００８４】
第１１図は、底付容器１内側の加工方法の一例を示す説明図である。まず、クランプ装置１５０および反力受け１４８により固定テーブル１４１を底付容器１内側の所定位置にて固定する。つぎに、同図（ａ）に示すように、固定テーブル（図示せず）に沿ってスピンドルユニット１４６を所定の切削速度にて移動させ、工具１４７による底付容器１内側の切削を行う。当該位置での切削が完了すると、クランプ装置１５０を外して固定テーブル１４１を解放する。つぎに、同図（ｂ）に示すように、回転支持台１５４上で胴本体１０１を９０度回転させ、クランプ装置１５０にて固定テーブル１４１を固定する。そして、上記同様に工具１４７にて切削を行う。以降、前記同様の工程をさらに２回繰り返す。
【００８５】
つぎに、スピンドルユニット１４６を１８０度回転させ、第１１図（ｃ）に示すように、順次、キャビティ１０２内の切削を行う。この場合も、上記同様に胴本体１０１を９０度回転させながら加工を繰り返す。この後、第１１図（ｄ）に示すように、スピンドルユニット１４６にスペーサ１５５を取付けることで当該スピンドルユニットの位置を高くする。そして、当該位置にて工具１４７を軸方向に送り、底付容器１内側の切削を行う。これを９０度回転させながら繰り返すことで、使用済み核燃料を収納する角パイプ（図示せず）を挿入するのに必要な形状がほぼ完成する。なお、専用機に拠らず一般の横中抉り機や縦型の中繰り機でも加工することができる。
【００８６】
なお上記の説明では、底付容器１を横にして外側および内側切削加工する例について説明したが、つぎに説明する加工装置によって、底付容器１を縦にして容器外側および内側を切削加工してもよい。
【００８７】
具体的には、この加工装置は、加工対象の底付容器を載せて回転させる回転テーブルと、底付容器を前記回転テーブルに載せ、加工終了後には回転テーブルから移動させるためのクレーンと、ベースの上に載せられた可動テーブルと、当該可動テーブルの上に載せられ可動テーブルの可動方向と直角方向に移動できるサドルと、サドルの上に載せられ上下に移動するアームを支えるコラムと、コラムに鉛直方向に対して上下可能に取付けられ、工具を取付けたアタッチメントを先端に備え、加工物に対して上下に移動して加工対象物を加工するアームを供えている。この加工装置は、アームの先端に取付けるアタッチメントを取り替えることによって、フライス加工、穴あけ加工等さまざまな加工に対応できるものである。
【００８８】
底付容器の加工を始めるときには、前記クレーンによって加工対象の底付容器を回転テーブルの上に載せ、中心出しをした後底付容器を回転テーブル上に固定する。底付容器の外側を円筒状に切削するときには、アームに取付けられたアタッチメントにバイトを取付け、回転テーブルを所定の回転数で回転させながら、このバイトによって底付容器を切削加工する。ここで、アームが取付けられているコラムはサドルの上に載せられているので、サドルおよび可動テーブルを動かすことにより、アームを移動させることができる。したがって、アームを任意の位置に移動させて、任意の切り込み量を設定することができる。また、アームは上下に移動できるので、このアームを底付容器の軸方向全体にわたって動かすことによって、底付容器の側面全体を切削できる。これらの動きには精度が要求されるため、サーボモータあるいはステッピングモータ等の回転運動をボールねじ等によって直線運動に変換して前記可動テーブル等を移動させることが望ましい。
【００８９】
径方向断面外形状が円形である底付容器の外周を切削して、例えば八角柱等の多角柱状に加工したいときには、例えば正面フライス用のアタッチメントをアームに取付け、正面フライス削りによって底付容器の側面を切削する。アームを上下させて底付容器の軸方向全体にわたって一面を削り出したら、回転テーブルを４５度回転させてつぎの側面を加工する。この作業を八回繰り返すと径方向の断面外形状が八角径の底付容器を製造できる。このようにして、任意の多角形断面を持つ底付容器を製造できる。
【００９０】
使用済み核燃料を収納するキャスクとして底付容器を使用するときには、底付容器の内形状は使用済み核燃料集合体を収納するバスケットの外周の少なくとも一部に合わせた形状とすることが望ましい。容器内に前記バスケットを容易に挿入し、固定できるからである。このような断面形状としては、例えば図１５（ｄ）に示すようなものがある。底付容器の内側をこのような形状に成形するには、アームに取付けるアタッチメントを例えばエンドミル用のものに変更して、断面内の角部が階段状になるように加工する。
【００９１】
まず、サドルおよび可動テーブルを動かして、アームを回転テーブルに載せられた底付容器の上まで移動する。つぎに、アームを下げて底付容器の内部に、エンドミルを取付けたアタッチメントを挿入して、エンドミルの位置決めをする。その後、所定の切り込み量を与えて底付容器の内側を切削する。何度か切り込みを加えて切削し、所定の形状が得られたら一段目の切削は完了する。一つの角部において必要な階段状の形状が得られたら、回転テーブルを９０度回転させて、次の角部を加工する。この作業を四回繰り返すと図１５（ｄ）に示したような径方向断面内形状を持つキャスク用底付容器を製造できる。
【００９２】
なお、底付容器の内側を切削加工するときには、切削屑や切削油の逃げ場がないため、加工の途中で切削できなくなってしまう。このため、例えばバキュームポンプ等の排出手段によって切削屑等を加工中の底付容器内部から除去することが望ましい。
【００９３】
底付容器を縦にして切削加工すると、横置きにした場合と比較して切削屑等の処理は必要になるものの、重力による変形の影響は低減できる。なお、この加工装置を上下反転して構成すれば、底付容器は開口部を下にして加工されるので、、底付容器の内側を切削加工する際には容易に切屑等を排出できる。
【００９４】
つぎに、本発明の方法で製造した底付容器を使用済み核燃料収納容器であるキャスクに適用した例について説明する。第１２図は、この発明の実施の形態に係るキャスクを示し、（ａ）は軸方向断面図、（ｂ）は径方向断面図である。このキャスク１００は、内部にバスケット３を備えた底付容器１と、底付容器１の外側に設けられたレジンやシリコーンゴム等の中性子遮蔽材２と、キャスク１００の外面になる外筒４とから構成されている。なお、底付容器１は上記の切削加工によって内側と外側とを成形したものである。
【００９５】
この底付容器１の上部には、一次蓋５および二次蓋６が設けられ、当該二次蓋６には中性子を遮蔽するためのレジン７が封入されている。また、底付容器１は、押し抜き絞り加工により形成した底付きの円筒形状であって、γ線遮蔽機能を有する炭素鋼またはステンレス鋼からなる。
【００９６】
前記中性子遮蔽材２は、水素を多く含有する高分子材料であって中性子遮蔽機能を有する。また、底付容器１の下部には、レジンやシリコーンゴム等の中性子遮蔽材８を封入した遮蔽体９が取付けられている。前記バスケット３は、使用済み核燃料集合体（図示省略）を収容するセルを格子状に配置したものであり、ボロンとアルミニウムとの複合材料から構成されている。
【００９７】
また、耐圧容器としての密閉性能を確保するため、一次蓋５および二次蓋６と底付容器１との間には金属ガスケットを設ける。前記底付容器１と外筒４との間には熱伝導を行う複数の銅製内部フィン１０が溶接されており、前記中性子遮蔽材２は、この内部フィン１０によって形成される空間に流動状態で注入され、発熱固化される。前記一次蓋５および二次蓋６は、γ線遮蔽機能を有する炭素鋼製或いはステンレス鋼製である。
【００９８】
上記キャスク１００では、底付の底付容器１を用いているから、従来のような底板を溶接する場合に比べて、製造の手間を省くことができる。また、従来では底付容器に底板を溶接していたので、溶接の品質により当該部分における密閉性が左右されることになっていたが、このような底付の底付容器１であれば当該部分における密閉性の問題は極めて少なくなる。なお、この発明のキャスク１００を実現するにあたっては、底付容器１内のバスケット３の形状や材質、中性子遮蔽材２の充填状態、内部フィン１０の数や位置などは、上記第１２図に示した例に限定されない。
【００９９】
実施の形態１に係る底付容器の製造方法は、円筒の直径に対して肉厚の厚い、いわゆる厚肉容器の製造に適している。さらに本発明の製造方法は、いわゆる厚肉容器の中でも、特に軸方向長さと内径とが１：１以上の容器を製造する場合に適している。この比率を超えるようになると、一般的な熱間加工では成形が進むにつれてプレス圧が増加するが、本実施の形態に係る製造方法は加工の始めと終わりとでプレス圧が大きく増加しないからである。本実施の形態に係る製造方法は、具体的には、例えば直径に対して肉厚が厚く、さらに軸方向の長さが数メートルにも及ぶ大型の底付容器であるキャスク等を製造する場合に特に適している。
【０１００】
従来このような大型で厚肉の底付一体の容器を製造するためには、数万ｔｏｎ規模のプレス機が必要であった。しかし、本発明に係る製造方法でこのようないわゆる厚肉の大型底付容器を製造すると、プレス圧力が一万ｔｏｎ程度で済むため、数万ｔｏｎのプレス機を使用しなくとも既存の大型プレス機によって成形できる。また、成形後の容器は端面形状に優れており、また表面および内部欠陥もほとんど発生しないため、成形後の修整はほとんど不要となる。なお、本発明の製造方法は、このような厚肉の大型底付容器に限られず、比較的肉厚の薄い放射性物質収納容器であるキャニスタも製造することができる。
【０１０１】
また、本発明の製造方法によって、大型プレス機用シリンダや化学プラント用容器、石油精製プラント用のリアクタ容器、アンモニア合成槽、あるいは熱交換器用容器、ボイラー等の圧力容器、水力発電用の水車を収める大型回転機器用のケーシング、潜水艦あるいは潜水艇の胴等も製造することができる。また、本発明の方法に使用できる材料は炭素鋼に限らず、ステンレス鋼、低合金鋼等の鉄系材料の外、ニッケル合金やアルミ合金、銅合金、マグネシウム合金などの非鉄金属も含まれる。
【０１０２】
（実施の形態２）
第１３図は、この発明の実施の形態２に係る底付容器を示す斜視図である。第１３図に示す底付容器１は、その外形および内形ともに八角形であることに特徴がある。また、容器の外形または内形のうち少なくとも一方を多角形としてもよい。放射性物質格納容器であるキャスクの底付容器には燃料棒の集合体を支えるバスケットが収容されるので、特にキャスクにおいては底付容器の内形状をバスケットに合わせた形状に成形するようにするのが好ましい。したがって、キャスクの内形は円状よりも多角形状である方が望ましい。そして、キャスクの内形を多角形とした場合には、キャスク胴の肉厚をできるだけ均一にした方が寸法や重量の点で有利であることから、キャスク胴の外形も多角形とすることが望ましい。この底付容器はこのような要求に対応できるものである。
【０１０３】
第１４図は、実施の形態２に係る底付容器を製造するためのコンテナ胴とポンチとを示す断面図である。成形用コンテナの胴部３００はその内部の断面形状が略八角形をしており、また、穿孔ポンチ４１０の外形も略八角形状である。実施の形態１で説明した熱間拡張成形法でこの成形用コンテナの胴部３００と穿孔ポンチ４１０とを使用すれば、熱間拡張成形時における荷重の増加を抑制しつつ、成形終了後における加工物の表面欠陥を抑制し、また端面形状に優れた多角形断面の底付容器を製造することができる。
【０１０４】
第１５図は、実施の形態２に係る製造方法によって成形できる底付容器の例を示す軸方向に垂直な断面図である。成形用コンテナ胴部の断面および穿孔ポンチの外形を適宜変更することによって、このような断面形状を有する底付容器を成形することができる。特にキャスクの内形を形成する穿孔ポンチ４１０は使用済み核燃料を収納するバスケットの形状に合わせて適宜変更することが望ましい。例えば、同図（ｄ）に示すような内断面形状をその外形とする穿孔ポンチを使用すれば、バスケットの形状に合わせた内形を成形できる。
【０１０５】
第１６図は、実施の形態２に係る製造方法によって成形できる底付容器の例を示す軸方向断面図である。成形用コンテナ３００の底部の内形および穿孔ポンチ４１０の先端形状を、底付容器の底の形状に合わせることで、これらの容器を成形することができる。同図（ｄ）に示す容器は、成形後に底部に孔を穿孔してもよいし、先端に突起を設けた穿孔ポンチによって成形してもよい。このようにして成形した容器は、胴部と一体として形成される底部が平面ではなく曲面が必要である容器に使用することができる。例えば、水力発電用の水車を収める大型回転機器用のケーシング等に適用できる。
【０１０６】
（実施の形態３）
第１７図は実施の形態３に係る底付容器を示す軸方向断面図である。この底付容器１は、胴と底とを一体に成形すると同時に、容器の底にざぐり部も形成する点に特徴がある。従来は厚肉円筒にざぐり部を設けた底を溶接によって取付けていたが、この製造方法では底にざぐり部を設ける工程の他に、溶接工程や溶接後の熱処理工程が必要であるため、製造に手間を要するという問題があった。本発明に係る底付容器を製造する方法によれば、一工程でざぐり部を設けた底を、胴と一体として成形できるため、製造が非常に容易になるという利点がある。
【０１０７】
第１８図は底付容器にざぐり部８００を設ける方法を示した説明図である。同図（ａ）に示すように、ポンチ４１０を押し込んで熱間拡張成形する前に、予め成形用コンテナの底部３０１に筒状の部材である円筒３０２を設けておく。ここで、この円筒３０２のみでもざぐり部８００は形成できるが、金属ビレット２００の成形後にこの円筒３０２を取り出しやすくするために、予めこの円筒３０２の上部に環状の金属板３０３を載せてもよい（同図（ａ）参照）。環状の金属板３０３は、その径方向の幅を円筒３０２の径方向の幅よりもやや大きくしてある。このようにすることで、金属ビレット２００を底付容器へ成形した後に円筒３０２を容易に取り外すことができる。なおこの場合、環状の金属板３０３は底付容器の成形後にその底部に嵌め殺すことになる。
【０１０８】
円筒３０２のみでざぐり部８００を成形するときには、円筒が金属ビレット２００と接する側における円筒の径を、円筒が成形用コンテナ３００の底部３０１と接する側における径よりも小さくすることが望ましい。すなわち、プレス方向に向って円筒３０２の径が大きくなるように、円筒３０２にテーパーを設けることが望ましい。このようにすることで、熱間拡張成形した後の金属ビレット２００から、円筒３０２を取り外しやすくなる。
【０１０９】
金属ビレット２００をコンテナの胴部３００に装入して円筒３０２および環状の金属板３０３の上に載せ（第１８図（ｂ））、ポンチ４１０をビレット２００に押し込んで底付容器の形に熱間拡張成形する（第１８図（ｃ））。こうして成形した金属ビレット２００の底部には、第１８図（ｄ）に示すように、円筒３０２および環状の金属板３０３によって環状の溝が形成される。このままでは単に環状の溝を設けたに過ぎないので、ざぐり部８００を形成するためにガスバーナー等の切断手段（図示せず）によって環状の溝内部に存在する柱状の部分である円柱部を切断する。このようにして、底部にざぐり部８００を備えた底付容器を製造することができる（第１８図（ｅ））。なお、ざぐり部８００は必要に応じて切削加工等によって仕上げてもよい。
【０１１０】
また、第１８図（ｂ'）に示すように、円筒３０２の代わりに円柱３０４を使用しても、底付容器の底部にざぐり部８００を形成することができる。なお、この場合にも円柱３０４の上に金属板３０５を載せて成形することができる（第１８図（ｃ'））。円筒３０２を使用した場合と異なり、円柱３０４を使用した場合は底付容器を成形すると同時にその底部にざぐり部８００を形成できる（第１８図（ｅ'））。このため、同図（ｄ）に示す円柱部を切断する工程は不要であるが、その一方で円筒３０２を使用した場合よりも大きなプレス圧力が必要となる。したがって、プレス機の性能、製造する底付容器の大きさ等を考慮した上で、円筒３０２あるいは円柱３０４のうちいずれを使用するかを決定することが望ましい。
【０１１１】
なお、円柱３０４のみでざぐり部８００を形成する場合には、プレス方向の前方側に向って大きくなるテーパーを設けておくことが望ましい。すなわち円柱３０４の軸方向断面が台形状の円柱とすることが望ましい。このようにすることで、熱間拡張成形した後の金属ビレット２００から、円筒３０２を取り外しやすくなる。
【０１１２】
なお、上記円筒３０２および円柱３０４の軸方向に垂直な断面の形状を変更することによって所望の断面形状を備えたざぐり部８００を成形することができる。例えば、軸方向に垂直な断面の形状を多角形にすることによって、内面形状が多角形のざぐり部８００を形成することができる。このようにすることで、底付容器の外形に合わせたざぐり部を形成することができるため、ざぐり部における径方向の肉厚を一定に保つことができる。
【０１１３】
第１９図は本発明に係る製造方法で成形できる底付容器の例を示した軸方向断面図である。第１９図（ａ）および（ｂ）に示す底付容器１は、上記説明において、円筒あるいは円柱の径を適宜選択することによって成形できる。同図（ｃ）は底部に二段のざぐり部８００を設けた例である。二段のざぐり部８００を設けるには、例えば、径の異なる二個の円柱を積み重ねた形状をした、軸方向の断面が凸形の成形冶具を金属ビレット２００の底に設置することで成形できる。また、径および高さの異なる二個の円筒を、金属ビレット２００の底に設置することでも成形できる。また円筒の外側面に、軸方向に対して段部を設けて使用してもよい。
【０１１４】
（実施の形態４）
第２０図は、この発明の実施の形態４に係る底付容器を示す軸方向断面図である。この底付容器１は、実施の形態１に示した製造方法において、熱間拡張成形前に成形した張出部２０１（第２図（ｂ）参照）をそのまま容器のフランジとして利用する点に特徴がある。使用済み核燃料収納容器であるキャスクは、一次蓋と二次蓋との間に数気圧のヘリウムガスを封入しているため、二次蓋の取付け部には大きな力がかかる。また、二次蓋は落下の衝撃を受ける場合もあるので、二次蓋の取付け部であるフランジ部は強固な構造であることが求められる。本発明に係る容器は、フランジを胴体と一体として成形しており、また胴体の径よりも大きくしてあるのでボルトを二列に配置する等の手段もとりやすい。したがって、二次蓋をより強固に固定することができる。
【０１１５】
従来のキャスクではフランジ部を別に製造してキャスク胴と溶接して取付けていたため、製造に手間を要していた。本発明の製造方法によれば、端面形状に優れた底付の厚肉容器を製造できるため、容器端面に形成した張出部２０１（第２図（ｂ）参照）をほとんど加工せずにフランジとして利用できる。したがって、溶接および溶接後熱処理工程を省略することができ、製造工程を簡略にできる。なお、第２０図では、熱間拡張成形前に成形した張出部２０１（第２図（ｂ）参照）をそのまま容器のフランジとして利用しているが、この張出部２０１を切削加工等によって取り除き容器開口部の内側に加工を施して、これまで使用されてきた張り出しのないフランジを形成することもできる。この場合もフランジ部と胴体とが一体に成形されているため、強度および密閉性を十分に確保できる。
【０１１６】
（実施の形態５）
つぎに、底付容器１の別の製造方法について説明する。第２１図〜第２６図は、第１２図に示したキャスク１００の底付容器１の製造工程を示す説明図である。この底付容器１の成形は、据え込み工程と押し抜き絞り工程とを組み合わせて行われる。
【０１１７】
まず、プレス加工機（図示省略）のスライドテーブル２０上にリング状の第１ダイス２１、第２ダイス２２および第３ダイス２３を積み重ね、この第１ダイス２１〜第３ダイス２３の中に第１加圧台２４、第２加圧台２５および第３加圧台２６を配置し、型を構成する（第２１図の（ａ））。金属ビレットＷの上面には穿孔ポンチ２７が位置する。この穿孔ポンチ２７は、プレス加工機のパンチに取付けたステム２８によって加圧される（第２１図の（ｂ））。金属ビレットＷは、前記第１ダイス２１内に設置される。当該金属ビレットＷは真空鋳造により成形した低炭素鋼またはステンレス鋼からなり、上面が円形で下面が上面より小さな円形となる円錐台形状である（傾斜面角度は図示省略）。加圧加工時、金属ビレットＷは１０００℃〜１２００℃の範囲内に加熱されている。当該加熱は電気炉にて行い、赤めた状態でスライドテーブル２０上に設置する。なお、ここで第１ダイス２１と金属ビレットＷとの間に、上述した円筒３０２および環状の金属板３０３（第１８図（ａ）参照）を設け、底部にざぐり部を形成してもよい。
【０１１８】
つぎに、金属ビレットＷを設置したら、穿孔ポンチ２７を加圧して据え込み加工を行う（第２１図の（ｃ））。第１ダイス２１の内端部は開口形状になっているから、穿孔ポンチ２７と第１ダイスの開口部分２１ａとの間に素材が流れ、金属ビレットＷが皿状に変形する。続いて、吊冶具２９を用いて第１ダイス２１ごとステム２８を吊り上げ（第２１図の（ｄ））、スライドテーブル２０を移動させて搬出し、第１加圧台２４を取り外す（（第２１図の（ｅ））。
【０１１９】
第１ダイス２１ごと金属ビレットＷを吊り上げたら、この状態で第２ダイス２２上にスペーサ３０を設置する（第２２図の（ａ））。続いて、スライドテーブル２０を移動させて型を搬入し（第２２図の（ｂ））、そのまま穿孔ポンチ２７を押し下げ、第１ダイス２１により押し抜き絞り加工を施す（第２２図（ｃ））。これにより、金属ビレットＷが第１ダイス２１を通過するときに頂部の皿状部分が絞られ、カップ形状になって第２ダイス２２内に位置する。つぎに、ステム２８および吊冶具２９とを上方に退避させ、スライドテーブル２０を移動させて金属ビレットＷおよび型を搬出するとともにスペーサ３０を取り外す（第２２図の（ｄ））。
【０１２０】
この状態で穿孔ポンチ２７は、カップ形状になった金属ビレットＷの底に残る（第２３図の（ａ））。つぎに、スペーサ３０を取り外した状態でステム２８を降下させ、穿孔ポンチ２７により加圧する（第２３図の（ｂ））。これによって金属ビレットＷがさらに据え込まれ、第２ダイス２２の開口部分２２ａと穿孔ポンチ２７との間から素材が流れて、金属ビレットＷが変形する。続いて、吊冶具２９を用いて第２ダイス２２を金属ビレットＷごと吊り上げる（第２３図の（ｃ））。この状態でスライドテーブル２０を移動させて型を搬出し、第２加圧台２５を取り外す（第２３図の（ｄ））。
【０１２１】
つぎに、第３ダイス２３上にスペーサ３１を設置する（第２４図の（ａ））。続いて、スライドテーブル２０を移動させて型を搬入し（第２４図の（ｂ））、そのまま穿孔ポンチ２７を押し下げ、第２ダイス２２により押し抜き絞り加工を施す（第２４図（ｃ））。これにより、金属ビレットＷが第２ダイス２２を通過するときに腹部が絞られてカップ状になる。つぎに、ステム２８および吊冶具２９とを上方に退避させ、スライドテーブル２０を移動させて金属ビレットＷおよび型を搬出するとともにスペーサ３１を取り外す（第２４図の（ｄ））。この状態で穿孔ポンチ２７は、カップ形状になった金属ビレットＷの底に残ることになる。
【０１２２】
つぎに、スライドテーブル２０を移動させて金属ビレットＷをステム２８の下方に位置させ（第２５図の（ａ））、ステム２８を降下させて穿孔ポンチ２７により金属ビレットＷを加圧する（第２５図の（ｂ））。これによって金属ビレットＷがさらに据え込まれ、第３ダイス２３の開口部分２３ａと穿孔ポンチ２７との間から素材が流れて、金属ビレットＷが変形する。続いて、吊冶具２９を用いて第３ダイス２３を金属ビレットＷごと吊り上げる（第２５図の（ｃ））。この状態でスライドテーブル２０を移動させて、第３加圧台２６を取り外す（第２５図の（ｄ））。
【０１２３】
つぎに、スライドテーブル２０上にスペーサ３２を設置する（第２６図の（ａ））。続いて、スライドテーブル２０を移動させてスペーサ３２を搬入し（第２６図の（ｂ））、そのまま穿孔ポンチ２７を押し下げ、第３ダイス２３により押し抜き絞り加工を施す（第２６図（ｃ））。これにより、金属ビレットＷが第３ダイス２３を通過するときにその腹部が絞られる。つぎに、ステム２８および吊冶具２９とを上方に退避させ、スライドテーブル２０を移動させて金属ビレットＷを搬出するとともにスペーサ３２を取り外す（第２６図の（ｄ））。この状態で穿孔ポンチ２７は、カップ形状になった金属ビレットＷの底に残っているが、このまま底付容器１の底として使用する。なお、穿孔ポンチ２７を取り除いて使用することも可能である。また、スライドテーブル２０を移動させてスペーサ３２を搬入したときに（第２６図の（ｂ））、スペーサ３２の内部に円筒スペーサ３０２（第２図（ｅ´´）参照）を設けて、穿孔ポンチ２７によって金属ビレットＷの底部を打ち抜けば、この方法によっても円筒容器を成形できる。
【０１２４】
上記成形が終了したら、所定の熱処理を施し、底付容器内面の機械加工を行う。このようにして成形した底付容器１は、金属ビレットＷからの断面減少率が４０％程度になる。また、通常の後方押出成形により底付容器を成形する場合に比べると、後方押出成形による場合は、底付容器の底部が厚くなり、キャスクの重量増加を招くことになる。また、プレス機械に大きな圧力を持ったものが必要になり、底付容器の規模によっては製造できない場合がある。これに対して、この実施の形態に係る製造方法によれば、上記のように据え込みと押し抜き絞りとを組み合わせて成形を行うので、据え込み時或いは絞り時の圧力がそれぞれ小さくてよい。このため、従来から使用されている大型のプレス加工機を用いて成形することが可能になる。
【０１２５】
第２７図は、上記底付容器の他の製造方法を示す説明図である。上記製造方法では、これまで説明したように、円筒形状の穿孔ポンチ２７および加圧台２４〜２６と、内部円リング形状のダイス２１〜２３を用いていたが、これら穿孔ポンチ２７などはこれらの形状に限定されない。例えば同図（ｂ）に示すように、底付容器１の外形を８角形にする場合には、第１ダイス２１ｂ〜第３ダイスの内部形状を８角形にすればよい。この場合、ダイス内に設置する加圧台２４ｂも８角形になる。
【０１２６】
また、底付容器１の内形を８角形にする場合には、同図（ｃ）に示すように、穿孔ポンチ２７ｃを８角柱にすればよい。この場合の金属ビレットＷは、８角錐台形状になる（テーパー角度の詳細は図示省略）。さらに、底付容器１の内形を段付とする場合には、同図（ｄ）に示すように、穿孔ポンチ２７ｄを段付き形状の角柱にすればよい。なお、図示しないが、底付容器の内外形を８角形にする場合には、同図（ｂ）に示したダイス２１ｂと、同図（ｃ）に示した穿孔ポンチ２７ｃを用いればよい。また、８角形以外であっても、当該発明の製造方法によれば、穿孔ポンチ、ダイスなどの形状を変えることで上記同様に成形可能である。なお、第２７図に示した穿孔ポンチ２７ｃおよび２７ｄは上記実施の形態１に係る製造方法にも適用できる。
【０１２７】
第２８図は、異なる製造方法の実施の形態を示す説明図である。この製造方法は、ステム５１をプレス加工機のスライドテーブル５２上に設置するとともにこのステム５１の頂部に穿孔ポンチ５３を取付け、加圧台５４をプレス加工機のパンチ５５に取付けることで実現する。すなわち、同図（ａ）に示すように、穿孔ポンチ５３に金属ビレットＷを載せ、プレス加工機のパンチ５５を降下させることで、第１ダイス５６による金属ビレットＷの据え込み加工を行う。
【０１２８】
つぎに、金属ビレットＷの下端が皿状に変形したら、パンチ５５を退避させて金属ビレットＷごと搬出する（図示省略）。そして、第１ダイス５６の上部に複数のスペーサ５７を載せ、パンチ５５の下方に搬入する。また、加圧台５４は、パンチ５５から取り外しておく。この状態でパンチ５５を降下させて加圧すると、同図（ｂ）に示すように、第１ダイス５６により金属ビレットＷが絞られる。この第１ダイス５６は、そのまま下方に退避する。
【０１２９】
つぎに、上記同様に金属ビレットＷを搬出してスペーサ５７を取り外すとともに加圧台５４を取付け、再びパンチ５５の下方に搬入する（図示省略）。また、パンチ５５側には、第２ダイス５８が取付けられる。この状態でパンチ５５を降下させ、金属ビレットＷを据え込み加圧する（同図（ｃ））。続いて、一旦、金属ビレットＷを搬出してからその第２ダイス５８上に複数のスペーサ５９を設置するとともに加圧台５４を取り外し、再び搬入する。そして、この状態でパンチ５５を降下させて加圧すると、同図（ｄ）に示すように、底付容器１の腹部が絞られる。この第２ダイス５８は、このまま下方に退避する。
【０１３０】
続いて、上記同様、金属ビレットＷを搬出してスペーサ５９を取り外し、再びパンチ５５の下方に搬入する（図示省略）。また、パンチ５５側には、第３ダイス６０および加圧台５４が取付けられる。この状態でパンチ５５を降下させて金属ビレットＷを加圧すると、同図（ｅ）に示すように、金属ビレットＷがさらに変形する。そして、一旦、金属ビレットＷを搬出してからその第３ダイス６０上に複数のスペーサ６１を設置するとともに加圧台５４を取り外し、再び搬入する。そして、この状態でパンチ５５を降下させて加圧すると、同図（ｆ）に示すように、底付容器１の腹部が絞られる。この第３ダイス６０は、このまま下方に退避する。なお、本発明の方法に使用できる材料は炭素鋼、ステンレス鋼、低合金鋼等の鉄系材料の外、ニッケル合金やアルミ合金、銅合金、マグネシウム合金などの非鉄金属も含まれる。
【０１３１】
具体的な成形条件について説明する。低炭素鋼の金属ビレットを用いてこれを１０００℃に加熱し、歪速度を０．１〜1ｓとするとき、その変形抵抗は、１．５〜３ｋｇｆ／ｍｍ²となる。例えば、１ｍの長さを１分で押し抜くとして、外径２５００ｍｍから２２００ｍｍへの減少を３０度ダイスで行う場合、内径を１４２０ｍｍとすると、歪は、
ｌｎ（（２５００²−１４２０²）／（２２００²−１４２０²））＝０．４
となり、これを時間（２５００−２２００／２／ｔａｎ３０°）／（１０００／６０）＝１５．６ｓｅｃで加工することになる。したがって、このときの歪速度は０．０２５^-1ｓとなる。
【０１３２】
つぎに、押し抜き力は、変形抵抗が３ｋｇｆ／ｍｍ²のとき摩擦係数を０．３とすると、
３×π／４×（２２００²−１４２０²）×ｌｎ（（２５００²−１４２０²）／（２２００²−１４２０²））×（１＋０．１×０．３／ｔａｎ３０°）＋４π／（６・３・√３）＝５４６０６４０ｋｇｆ
となる。しかし、初期には温度が高いので、押し抜き力は半分の２７３０ｔｏｎｆになる。また、押し抜き時に底が抜けないための最終厚みは、
５４０６４０／（３／√３）／π／１４２０＝７０７ｍｍ
であり、したがってこれ以上が必要となる。
【０１３３】
製品長４８８５ｍｍのとき素材長は、
４８８５×（２２００²−１４２０²）／２２００²＝２８５０ｍｍ
であるから、一回の据え込み量を１／３の９５０ｍｍ、型拘束部までの高さを最終底厚みの７００ｍｍとすると、必要な据え込み力は、
３×π／４×１４２０²×（１＋０．３×１４２０／７００／２）＝６１９６７００ｋｇｆ
となる。この程度の圧力であれば、使用実績のある８０００ｔｏｎプレスによって成形可能である。
【０１３４】
これに対して、後方押出成形する場合の押出し力は、
３×π／４×２２００²×（ｌｎ（２２００²／（２２００²−１４２０²））×（１＋２×０．５／ｔａｎ４５°））＋４π／（４・３・√３）＝１９１８６１０３ｋｇｆ
となるから、２００００ｔｏｎプレスが必要になる。
【０１３５】
（付記）
つぎの発明に係る筒物または容器の製造方法は、金属ビレットを成形用コンテナに装入し、プレス加圧機によって作動する穿孔ポンチによって当該金属ビレットを熱間拡張成形するにあたって、プレス方向の前方側はコンテナの内径以下の対角線長さをもつ外径の断面形状であり、また後方側はコンテナの内径と略同等な外径もつ断面形状である金属ビレットを、プレス加工温度に加熱した後プレス成形用コンテナに装入する工程と、前記穿孔ポンチで該金属ビレットの加工物中心を穿孔しながらプレス加工する工程と、を備えたことを特徴とする。
【０１３６】
この方法では、プレス方向の前方側は対角線長さがコンテナの内径よりも小さい四角形断面の金属ビレットを使用するため、プレス方向の前方側における平面で構成された側面を曲げる作用によって、プレス圧力を従来よりも小さくできる。また、金属ビレットのプレス方向の後方側が、プレス方向の前方側の据え込みを抑制するため、端部や容器表面の欠陥も抑制でき、プレス圧力も低減できる。
【０１３７】
つぎの発明に係る筒物または容器の製造方法は、金属ビレットを成形用コンテナに装入し、プレス加圧機によって作動する穿孔ポンチによって当該金属ビレットを熱間拡張成形するにあたって、プレス方向の前方側はコンテナの内径よりも小さい対角線長さの外径をもつ断面形状であり、また後方側はコンテナの内径と略同等な対角線長さをもつ断面形状である金属ビレットを、プレス加工温度に加熱した後プレス成形用コンテナに装入する工程と、ポンチで該金属ビレットの加工物中心を穿孔しながらプレス加工する工程と、を備えたことを特徴とする。
【０１３８】
この方法では、プレス方向の前方側は対角線長さがコンテナの内径よりも小さい四角形断面の金属ビレットを使用するため、プレス方向の前方側における平面で構成された側面を曲げる作用によって、プレス圧力を従来よりも小さくできる。また、この方法に使用する金属ビレットはプレス方向の前方側および後方側ともに角断面形状であるため、丸断面形状と比較して金属ビレットを比較的容易に加工できる。
【０１３９】
つぎの発明に係る筒物または容器の製造方法は、金属ビレットを成形用コンテナに装入し、プレス加圧機によって作動する穿孔ポンチによって当該金属ビレットを熱間拡張成形するにあたって、プレス方向の前方側はコンテナの内径よりも小さい外径をもつ断面形状であり、また後方側はコンテナの内径と略同等な外径をもつ断面形状である金属ビレットを、プレス加工温度に加熱した後プレス成形用コンテナに装入する工程と、ポンチで該金属ビレットの加工物中心を穿孔しながらプレス加工する工程と、を備えたことを特徴とする。
【０１４０】
上記の容器の製造方法では、プレス方向の前方側は対角線長さがコンテナの内径よりも小さい円形断面であるため、金属ビレットと成形用コンテナの内壁との間に生ずる空間へ、金属ビレットが拡張する。このため、プレス圧力を従来よりも小さくできる。また、金属ビレットのプレス方向の後方側がプレス方向の前方側の据え込みを抑制するため、端部や容器表面の欠陥も抑制でき、プレス圧力も低減できる。
【０１４１】
つぎの発明に係る筒物または容器の製造方法は、金属ビレットを成形用コンテナに装入し、プレス加圧機によって作動する穿孔ポンチによって当該金属ビレットを熱間拡張成形するにあたって、プレス方向の前方側はコンテナの内径以下の対角線長さをもつ外径の断面形状で、また後方側はコンテナの内径と略同等な外径もつ断面形状である金属ビレットを、プレス加工温度に加熱した後プレス成形用コンテナに装入する工程と、前記金属ビレットを押し込むことにより当該金属ビレットのプレス方向の後方側を前記成形用コンテナの入口側端部に延出させる工程と、前記穿孔ポンチで該金属ビレットの加工物中心を穿孔しながらプレス加工する工程と、を備えたことを特徴とする。
【０１４２】
この筒物または容器の製造方法は、熱間拡張成形前にコンテナの胴部上に金属ビレットのプレス方向の後方側を延出させる工程を含んでいる。この延出部は、熱間拡張成形時に金属ビレットをコンテナ端部に係止する作用があるため、コンテナと金属ビレットとの拘束がより強くなって、プレス方向の前方側における据え込みを抑制できる。また、プレス方向の前方側は対角線長さがコンテナの内径よりも小さい四角形断面の金属ビレットを使用するため、四角形断面の各辺を曲げる作用によって拡張成形される。また、金属ビレットのプレス方向の後方側が、プレス方向の前方側の据え込みを抑制する。これらの相互作用によって、この製造方法では、後方押出し法等と比較して小さなプレス圧力で厚肉の容器を成形できる。
【０１４３】
つぎの発明に係る筒物または容器の製造方法は、金属ビレットを成形用コンテナに装入し、プレス加圧機によって作動する穿孔ポンチによって当該金属ビレットを熱間拡張成形するにあたって、プレス方向の前方側はコンテナの内径よりも少さい対角線長さの外径をもつ断面形状であり、また後方側はコンテナの内径と略同等な対角線長さをもつ断面形状である金属ビレットを、プレス加工温度に加熱した後プレス成形用コンテナに装入する工程と、前記金属ビレットを押し込むことにより当該金属ビレットのプレス方向の後方側を前記成形用コンテナの入口側端部に延出させる工程と、ポンチで該金属ビレットの加工物中心を穿孔しながらプレス加工する工程と、を備えたことを特徴とする。
【０１４４】
この筒物または容器の製造方法は、熱間拡張成形前にコンテナの胴部上に金属ビレットのプレス方向の後方側を延出させる工程を含んでいる。この延出部は、熱間拡張成形時に金属ビレットをコンテナ端部に係止する作用があるため、コンテナと金属ビレットとの拘束がより強くなって、プレス方向の前方側における据え込みを抑制できる。また、プレス方向の前方側は対角線長さがコンテナの内径よりも小さい四角形断面の金属ビレットを使用するため、四角形断面の各辺を曲げる作用によって拡張成形される。また、金属ビレットのプレス方向の後方側が、プレス方向の前方側の据え込みを抑制する。これらの相互作用によって、この製造方法では、後方押出し法等と比較して小さなプレス圧力で厚肉の容器を成形できる。さらに、この方法に使用する金属ビレットはプレス方向の前方側および後方側ともに角断面形状であるため、一方が丸断面形状の金属ビレットと比較して金属ビレットの加工が比較的容易である。
【０１４５】
つぎの発明に係る筒物または容器の製造方法は、金属ビレットを成形用コンテナに装入し、プレス加圧機によって作動する穿孔ポンチによって当該金属ビレットを熱間拡張成形するにあたって、プレス方向の前方側はコンテナの内径よりも少さい外径をもつ断面形状であり、また後方側はコンテナの内径と略同等な外径をもつ断面形状である金属ビレットを、プレス加工温度に加熱した後プレス成形用コンテナに装入する工程と、前記金属ビレットを押し込むことにより当該金属ビレットのプレス方向の後方側を前記成形用コンテナの入口側端部に延出させる工程と、ポンチで該金属ビレットの加工物中心を穿孔しながらプレス加工する工程と、を備えたことを特徴とする。
【０１４６】
この筒物または容器の製造方法は、熱間拡張成形前にコンテナの胴部上に金属ビレットのプレス方向の後方側を延出させる工程を含んでいる。この延出部は、熱間拡張成形時に金属ビレットをコンテナ端部に係止する作用があるため、コンテナと金属ビレットとの拘束がより強くなって、プレス方向の前方側における据え込みを抑制できる。また、金属ビレットのプレス方向の後方側は成形用コンテナの内径と略同径であるため、プレス方向の前方側の据え込みを抑制できる。これらの相互作用によって、この製造方法では、後方押出し法等と比較して小さなプレス圧力で厚肉の容器を成形できる。さらに、この方法に使用する金属ビレットはプレス方向の前方側および後方側ともに断面形状が円形であるため、断面形状が異なる金属ビレットと比較して加工が比較的容易である。
【０１４７】
【発明の効果】
以上説明したように、この発明に係る厚物金属製円筒物または円筒容器の熱間プレス成形法では、プレス方向の前方側はコンテナの内径よりも小さい外径または対角線長さの外径をもつ断面形状の部材もしくはコンテナの内径と同等の対角線長さの外径をもつ断面形状の部材で、また後方側はコンテナの内径と同等な外径または対角線長さをもつ断面形状の部材からなる異径断面形状の継目無金属ビレットを、プレス加工温度に加熱した後プレス成形用コンテナに装入し、しかる後ポンチで該継目無金属ビレットの加工物中心を穿孔しながらプレス加工した。このため、継目無金属ビレットがプレス成形荷重を低減させ且つ製品歩留りを向上させ、さらに端面形状の優れたプレス成形品が得られる。
【０１４８】
また、この発明に係る厚物金属製円筒物または円筒容器の熱間プレス成形法では、熱間拡張成形前にコンテナの胴部上に金属ビレットのプレス方向の後方側を延出させる工程を含むようにした。この延出部は、熱間拡張成形時に金属ビレットをコンテナ端部に係止する作用があるため、コンテナと金属ビレットとの拘束がより強くなって、プレス方向の前方側における据え込みを抑制できる。またプレス前方側は、コンテナの内径よりも小さい外径または対角線長さの外径をもつ断面形状の部材もしくはコンテナの内径と同等の対角線長さの外径をもつ断面形状の部材とした。このため、プレス後方側から金属が供給され且つ高温度に加熱された鋼の良好な塑性加工の作用効果が伴って側方に押し広げられながら加工されるため、コンテナの空間を充満し成形されるため、継目無金属ビレットから、所定形状のプレス製品に製造される。これらの相互作用によって、後方押出し法等と比較して小さなプレス圧力で厚肉の容器を成形できる。
【０１４９】
また、この発明に係る容器の製造装置では、コンテナ胴部とコンテナ底部とがコンテナ胴部の軸方向に対して相対的に移動できる成形用コンテナと、プレス加工機に取付けられ、前記成形用コンテナ内に装入された金属ビレットを加圧する穿孔ポンチとを備えるようにした。このため、熱間拡張成形時において、コンテナの胴部と成形される金属ビレットとはほとんど相対的に移動しないため、熱間拡張成形時におけるプレス圧力の増加を抑制できる。
【０１５０】
また、この発明に係る容器の製造装置では、さらに上記成形用コンテナの胴部を軸方向に分割した。このため、軸方向に長い金属ビレットを成形する場合であっても、熱間拡張成形時における金属ビレットの軸方向に対する変形をコンテナ全体で吸収できる。したがってプレス圧力の増加を抑制できる。
【０１５１】
また、この発明に係る熱間拡張成形用金属ビレットは、少なくともプレス方向の前方側における軸方向に垂直な断面形状を多角形に形成した。このため、多角形の辺を曲げる作用、および金属ビレットの据込みを抑制する作用が生ずる。これらの作用によって、従来よりも少ないプレス圧力で軸方向の長さと径との比が１以上の厚肉容器を成形できる。また成形後における容器の端部や表面に生ずる欠陥も抑制できる。
【０１５２】
また、この発明に係る熱間拡張成形用金属ビレットは、プレス方向の前方側における側面またはプレス方向の後方側における側面のうち少なくとも一方に、少なくとも一つの平面を備えた。熱間拡張成形時においては、この平面を曲げる作用によって拡張成形するため、熱間拡張成形時に要する力は側面が曲面である場合よりも小さくて済む。したがって、従来よりも小さいプレス圧力で軸方向に長い厚肉の容器を成形できる。また、側面が曲面である場合と比較して、割れ等の内部欠陥も低減できる。
【０１５３】
また、この発明に係る熱間拡張成形用金属ビレットは、上記熱間拡張成形用金属ビレットにおいて、さらに、前記金属ビレットのプレス方向の前方側に、プレス方向に向かって細くなるテーパーを設けた。また、この発明に係る熱間拡張成形用金属ビレットは、上記熱間拡張成形用金属ビレットにおいて、さらに、前記金属ビレットのプレス方向前方側が、プレス方向に向かって段階的に細くなるように少なくとも一以上の段部を設けた。これらの金属ビレットは、熱間拡張成形の最終段階において、成形用コンテナの底部付近に金属が充満するタイミングを遅らせることができる。このため、熱間拡張成形の最終段階において据込みを抑制し、その結果、熱間拡張成形時におけるプレス圧力を小さくすることができる。
【０１５４】
また、この発明に係る熱間拡張成形用金属ビレットは、プレス方向の後方側における端部に張出部を備えたので、この張出部が熱間拡張成形時に金属ビレットをコンテナ端部に係止する。この作用により、コンテナと金属ビレットとの拘束がより強くなってプレス方向の前方側における据え込みを抑制できる。また、側面に少なくとも一つの平面を備えたので、この平面を曲げる作用および金属ビレットの据込みを抑制する作用も生ずる。したがって、これらの相互作用によってプレス圧力を小さく抑えることができる。また、この金属ビレットは、製造時に予め張出部を金属ビレットのプレス方向の後方側に設けたので、容器の製造工程を簡略にすることができる。
【０１５５】
また、この発明の熱間拡張成形用金属ビレットでは、プレス方向の後方側に張出部を備えるようにしたため、この張出部が熱間拡張成形時に金属ビレットをコンテナ端部に係止する。この作用により、コンテナと金属ビレットとの拘束がより強くなってプレス方向の前方側における据え込みを抑制できる。また、少なくともプレス方向の前方側における軸方向に垂直な断面形状を多角形に形成したので、多角形断面の各辺を曲げる作用および金属ビレットの据込みを抑制する作用も生ずる。したがって、これらの相互作用によってプレス圧力を小さく抑えることができる。また、この金属ビレットは、製造時に予め張出部を金属ビレットのプレス方向の後方側に設けたので、プレス方向の後方側に張出部を形成する工程が不要となり、容器の製造工程を簡略にすることができる。
【０１５６】
また、この発明の熱間拡張成形用金属ビレットでは、プレス方向の後方側に張出部を備えたため、この張出部が熱間拡張成形時に金属ビレットをコンテナ端部に係止する。この作用により、コンテナと金属ビレットとの拘束がより強くなってプレス方向の前方側における据え込みを抑制できる。また、少なくともプレス方向の前方側における軸方向に垂直な断面形状を多角形に形成したので、上記曲げの作用および金属の流れを抑制する作用も生ずる。さらにプレス前方側はプレス方向に向かって段階的に細くなるようにしたので、熱間拡張成形の最終段階において据込み現象を抑制し、プレス圧力の増加を抑えることができる。したがって、これらの相互作用によってプレス圧力を小さく抑えることができる。また、この金属ビレットは、製造時に予め張出部を金属ビレットのプレス方向の後方側に設けたので、プレス方向の後方側に張出部を形成する工程が不要となる。
【０１５７】
また、この発明の熱間拡張成形用金属ビレットでは、プレス方向の後方側に張出部を備えたため、この張出部が熱間拡張成形時に金属ビレットをコンテナ端部に係止する。この作用により、コンテナと金属ビレットとの拘束がより強くなってプレス方向の前方側における据え込みを抑制できる。また、金属ビレットの側面のうち少なくとも一方に少なくとも一つの平面を備えたので、上記曲げの作用および金属の流れを抑制する作用も生ずる。さらにプレス前方側はプレス方向に向かって段階的に細くなるようにしているので、熱間拡張成形の最終段階において据込み現象を抑制し、プレス圧力の増加を抑えることができる。したがって、これらの相互作用によってプレス圧力を小さく抑えることができる。また、この金属ビレットは、製造時に予め張出部を金属ビレットのプレス方向の後方側に設けたので、プレス方向の後方側に張出部を形成する工程が不要となる。
【図面の簡単な説明】
【図１】実施の形態１に係る底付容器の一例を示す説明図である。
【図２】第１図に示した底付容器の製造工程を示す説明図である。
【図３】実施の形態１に使用する金属ビレットの一例を示す斜視図である。
【図４】実施の形態１に係る他のビレットを示す説明図である。
【図５】金属ビレットの変形の様子を示した概念図である。
【図６】実施の形態１に適用できる他の金属ビレットを示す斜視図である。
【図７】実施の形態１に適用できる他の金属ビレットを示す説明図である。
【図８】実施の形態１に使用するコンテナの胴部の分割部を示す断面図である。
【図９】熱間拡張成形した底付容器の外側を切削加工する装置を示す概略図である。
【図１０】底付容器の内側を加工する装置を示す概略図である。
【図１１】底付容器内側の加工方法の一例を示す説明図である。
【図１２】この発明の実施の形態に係るキャスクを示し、（ａ）は軸方向断面図、（ｂ）は径方向断面図である。
【図１３】実施の形態２に係る底付容器を示す斜視図である。
【図１４】実施の形態２に係る底付容器を製造するためのコンテナ胴とポンチとを示す断面図である。
【図１５】実施の形態２に係る製造方法によって成形できる底付容器の例を示す軸方向に垂直な断面図である。
【図１６】実施の形態２に係る底付容器を製造するためのコンテナ胴とポンチを示す断面図である。
【図１７】実施の形態３に係る底付容器を示す軸方向断面図である。
【図１８】底付容器にざぐり部を設ける方法を示した説明図である。
【図１９】本発明に係る製造方法で成形できる底付容器の例を示した軸方向断面図である。
【図２０】実施の形態４に係る底付容器を示す軸方向断面図である。
【図２１】第１２図に示した底付容器の製造工程を示す説明図である。
【図２２】第１２図に示したキャスクの底付容器の製造工程を示す説明図である。
【図２３】第１２図に示したキャスクの底付容器の製造工程を示す説明図である。
【図２４】第１２図に示したキャスクの底付容器の製造工程を示す説明図である。
【図２５】第１２図に示したキャスクの底付容器の製造工程を示す説明図である。
【図２６】第１２図に示したキャスクの底付容器の製造工程を示す説明図である。
【図２７】上記底付容器の他の製造方法を示す説明図である。
【図２８】異なる製造方法の実施の形態を示す説明図である。
【図２９】従来のキャスクの一例を示す断面図である。
【図３０】第２９図に示したキャスクの底付容器を製造する方法の一例を示す説明図である。
【図３１】エルハルト穿孔法によって底付容器を製造する方法を示す説明図である。
【符号の説明】
１００ キャスク
１ 底付容器
１ａ 胴部
１ｂ 底部
２ レジン
３ バスケット
４ 外筒
５ 一次蓋
６ 二次蓋
７、８ レジン
９ 遮蔽体
１０ 内部フィン
２０ スライドテーブル
２１〜２３ ダイス
２１ａ 開口部分
２４〜２６ 加圧台
２８ ステム
２９ 吊冶具
３０〜３２ スペーサ
Ｗ、２００ 金属ビレット
２０１ 張り出し部
２０２ リム
２０３ 突起
３００、３００ａ、３００ｂ コンテナの胴部
３０１ コンテナの底部
３０２ 円筒状のスペーサ
３０３ 環状の金属板
３０４ 円柱
３０５ 金属板
３１０ 位置決めガイド
３５０ 空間
４００ 大型ポンチ
２７、４１０、４１１ 穿孔ポンチ
８００ ざぐり部
９００、９１０、９２０ 軸方向に垂直な断面の投影像
９５０、９６０、９７０ 軸方向に垂直な断面[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thick-walled container in which a body portion and a bottom portion are integrally formed, or a thick-walled cylinder that can be used as a cylinder of a large press machine. The present invention relates to a hot press molding method for a thick metal cylinder or cylindrical container, a manufacturing apparatus for a bottomed container, and a metal billet for hot expansion molding.
[0002]
[Prior art]
Containers with cylinder heights and diameters of several meters are used for casks for storing, transporting, and temporarily storing spent nuclear fuel generated from nuclear reactors and for cylinders used in large press machines. ing. Some of these containers have a thickness of about several tens of centimeters from the viewpoint of shielding γ rays or withstanding high pressure. Here, a conventional container that has been used for these uses will be described by taking a cask for storing, transporting, and temporarily storing spent nuclear fuel as an example.
[0003]
FIG. 29 is a sectional view showing an example of a conventional cask. The cask 500 has a barrel 501a and a bottom 501b made of stainless steel or carbon steel, and forms a container 501. The cask 500 is disposed in the container 501 and contains a spent nuclear fuel assembly, and an outer periphery of the container 501. The neutron shield 503 is provided. The neutron shield 503 is filled in a space between the outer cylinder 504 and the container 501, and a plurality of heat transfer fins (not shown) are provided between the container 501 and the outer cylinder 504. The basket 502 is made of a material added with boron having neutron absorption ability.
[0004]
A stainless steel or carbon steel bottom plate 501b is TIG-welded (tungsten-inert gas welding) or SAW (submerged-arc welding). A neutron shielding material 506 is sealed in the bottom plate 501b. A primary lid 507 and a secondary lid 508 are attached to the upper portion of the container 501 with bolts. A neutron shielding material 509 is enclosed in the secondary lid 508.
[0005]
Γ rays generated from the spent fuel assembly are shielded by the body 501a, the bottom plate 501b, the primary lid 507, and the secondary lid 508. Neutrons are shielded by a neutron shielding material 503, a bottom plate 501b, and a neutron shielding material 506 enclosed in a secondary lid 508 and a secondary lid 508 provided on the outer periphery of the container 501. The decay heat of the spent fuel assembly is transmitted from the container 501 to the outer cylinder 504 through the heat transfer fins, and is radiated to the outside from there.
[0006]
Next, the method that has been used to produce the cask bottomed container shown in FIG. 29 will be described. FIG. 30 is an explanatory view showing an example of a method for producing the cask bottomed container shown in FIG. First, as shown in FIG. 2A, a metal billet 61 forged to a predetermined size is installed on an anvil 62 with a perforated hole, and a punch 63 is used for drilling. Next, as shown in FIGS. 5B to 5C, the mandrel 65 is passed through the hole 64 of the metal billet 61, and the hole 64 is widened by the hammer 66 while rotating. Subsequently, as shown in FIG. 4D, the mandrel 67 is replaced with a large-diameter mandrel, and hollow forging is performed using a hammer 68. As a result, the metal billet 61 is thinned and a cylindrical body is formed ((e) in the figure).
[0007]
FIG. 31 is an explanatory view showing a method for producing a bottomed container by the Erhardt perforation method. This method is a method of forming the metal billet 200 into a cylinder by pushing the punch 410 into the metal billet 200 charged in the container. The metal billet 200 has a rectangular cross-sectional shape, and the diagonal length is equal to the inner diameter of the barrel 300 of the container. Further, since the cross section of the metal billet 200 is rectangular, a space 350 exists between the metal billet 200 and the container ((a ′) in the figure). When the metal billet 200 is inserted into the barrel 300 of the container and the punch 410 is pushed into the central axis of the metal billet 200, a metal flow is generated by the metal bulging action of the punch 410. The metal flow fills the space 350, and a part of the metal flow rises in the body 300 of the container, so that the metal billet 200 is formed into a cylindrical shape ((b) in the figure).
[0008]
Further, the container with the bottom of the cask can also be manufactured by a backward extrusion pressing method (not shown). The backward extrusion press method is a method in which a metal billet having a circular cross section substantially equal to the inner diameter of the container is inserted into the container, and then the punch and the container are pressed by the compressive force of the punch pressed along the central axis of the metal billet. A metal flow is caused between. And it is the press work method which shape | molds a metal billet into a elongate cylindrical shape, raising a metal back.
[0009]
When the cylindrical body 501a is formed by any of the methods described above, the bottom plate 501b is welded to the lower part. Furthermore, in order to remove the thermal stress due to the welding, the container 501 is heat treated.
[0010]
[Problems to be solved by the invention]
However, in the conventional cask 500, since the bottom plate 501b is joined to the cylindrical body 501a by welding in order to form a bottomed container, it is necessary to perform heat treatment after welding. For this reason, there was a problem of requiring labor for manufacturing. Further, in the Erhardt perforation method, as shown in FIG. 31, the temperature drop at the metal tip that rises in the space 350 is damaged, and scratches and corrugated defects occur. Furthermore, as shown in the figure, a defective shape part ((b) in the figure) is inevitably generated at the end of the cylinder. Therefore, a certain amount of this part must be rounded down, resulting in a significant decrease in yield. It was.
[0011]
In the backward extrusion press method, the metal billet is formed while generating a high friction between the container and the metal billet. For this reason, the metal billet has a problem that many defects such as a wrinkle-like wrinkle and a streak-like wrinkle are generated on the surface, and it takes a long time for the repair work.
[0012]
Further, in both the Erhardt perforation method and the backward extrusion press method, when the size and thickness of the container to be molded are increased, the pressure required for pressing becomes extremely large. Therefore, with these methods, it has been difficult to produce a container having a large size and thickness. Therefore, the present invention has been made in view of the above, and provides either a container that does not require labor for manufacturing, or a container that can suppress defects that occur on the cylindrical end or the container surface. The goal is to achieve.
[0013]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the hot press molding method for a thick metal cylindrical object or cylindrical container according to the present invention is such that the front side in the pressing direction has an outer diameter or diagonal length smaller than the inner diameter of the container. A cross-sectional member with a diameter or a cross-sectional member with a diagonal length equivalent to the inner diameter of the container, and a cross-sectional member with an outer diameter or diagonal length equivalent to the inner diameter of the container on the rear side A seamless metal billet having a cross-sectional shape with different diameters is heated to the pressing temperature and then charged into a container for press molding, and then pressed while punching the center of the workpiece of the seamless metal billet with a punch. It is characterized by.
[0014]
In this press molding method, since the metal in the thick portion on the rear side of the press is processed while filling the container, the restraining force is increased, the upsetting phenomenon of the seamless metal billet is suppressed, and the end face shape is improved. In addition, the front side of the press is processed while being spread laterally with the effect of good plastic working of the steel that is supplied with metal from the rear side of the press and heated to a high temperature, thus filling the container space Therefore, it is manufactured from a seamless metal billet into a pressed product having a predetermined shape. As a result, the seamless metal billet reduces the press molding load and improves the product yield, and further, a press molded product having an excellent end face shape can be obtained.
[0015]
In the hot press molding method for a thick metal cylinder or cylindrical container according to the next invention, the front side in the pressing direction is a member having a cross-sectional shape having an outer diameter smaller than the inner diameter of the container or an outer diameter of a diagonal length. A cross-section member with an outer diameter of the diagonal length equivalent to the inner diameter of the container, and a cross section member having a cross-section shape with an outer diameter or diagonal length equivalent to the inner diameter of the container on the rear side After the metal-free billet is heated to the press processing temperature, it is inserted into the press-molding container, and the metal billet is pushed in so that the rear side in the pressing direction of the metal billet extends to the inlet side end of the molding container. After that, it is characterized in that it is pressed while punching the center of the workpiece of the seamless metal billet with a punch.
[0016]
This hot metal cylindrical or cylindrical container hot press forming method includes a step of extending the rear side of the metal billet in the press direction on the body of the container before hot expansion forming. Since this extending portion has an action of locking the metal billet to the container end during hot expansion molding, the restraint between the container and the metal billet becomes stronger, and upsetting on the front side in the press direction can be suppressed. . In addition, the front side of the press is processed while being spread laterally with the effect of good plastic working of the steel that is supplied with metal from the rear side of the press and heated to a high temperature, thus filling the container space Therefore, it is manufactured from a seamless metal billet into a pressed product having a predetermined shape. Due to these interactions, in this manufacturing method, a thick-walled container can be formed with a smaller pressing pressure than in the backward extrusion method or the like.
[0017]
An apparatus for manufacturing a bottomed container according to the next invention includes at least a container body and a container bottom, and the container body and the container bottom can be moved relative to the axial direction of the container body. And a perforation punch which is attached to a press machine and pressurizes the metal billet inserted in the molding container.
[0018]
This bottomed container manufacturing apparatus includes a container in which a bottom part and a body part can move relatively. For this reason, when the metal billet tries to move the barrel of the container in the direction opposite to the press direction during the hot expansion molding, the barrel of the container moves in the direction opposite to the press direction together with the metal billet. That is, since the barrel part of the container and the metal billet to be molded hardly move relative to each other, it is possible to suppress an increase in press pressure during hot expansion molding.
[0019]
An apparatus for manufacturing a bottomed container according to the next invention includes at least a container body portion and a container bottom portion which are divided in the axial direction, and the container body portion and the container bottom portion are in an axial direction of the container body portion. And a punch for punching the metal billet for hot expansion molding, which is attached to the press machine and inserted in the molding container. . In this bottomed container manufacturing apparatus, since the container body extends over the entire axial direction, even when forming a metal billet that is long in the axial direction, the deformation of the metal billet in the axial direction during hot expansion forming Can be absorbed by the entire container. Therefore, even when a container that is long in the axial direction is formed, an increase in press pressure can be suppressed.
[0020]
The metal billet according to the next invention is characterized in that at least a cross-sectional shape perpendicular to the axial direction on the front side in the pressing direction is formed into a polygon.
[0021]
Since this metal billet for hot expansion forming has a polygonal cross-sectional shape perpendicular to the axial direction at least on the front side in the pressing direction, the metal billet is bent by the action of bending each side of the polygon during hot expansion forming. Expansion molding toward the inner wall. At the time of hot expansion molding, the metal billet expands into a space existing between the front side in the pressing direction and the container body, so that the phenomenon of metal flowing in the opposite direction to the pressing direction is suppressed. With these actions, this hot-extrusion metal billet can form a thick container having a ratio of axial length to diameter of 1 or more with a press pressure that is a fraction of that of the prior art. Moreover, the defect which arises in the edge part and surface of a container after shaping | molding can also be suppressed.
[0022]
A hot billet forming metal billet according to the next invention is characterized in that at least one of a side surface on the front side in the pressing direction or a side surface on the rear side in the pressing direction is provided with at least one flat surface.
[0023]
This hot-extrusion metal billet has at least one plane on the side surface, and is expanded by the action of bending the plane toward the inner wall of the molding container. Can be smaller than when the is a curved surface. Therefore, it is possible to form a thick container that is long in the axial direction with a smaller pressing pressure than in the past. Also, internal defects such as cracks can be reduced as compared with the case where the side surface is a curved surface.
[0024]
The metal billet for hot expansion forming according to the next invention is such that, in the metal billet for hot expansion molding, a taper that is tapered toward the pressing direction is further provided on the front side in the pressing direction of the metal billet. Features.
[0025]
The metal billet for hot expansion forming according to the next invention is the above-mentioned metal billet for hot expansion molding, and further, at least one or more so that the front side of the metal billet in the pressing direction is gradually reduced toward the pressing direction. The step portion is provided.
[0026]
Since the metal billet for hot expansion forming described above can delay the timing at which the metal on the front side in the press direction fills the periphery of the bottom in the final stage of the hot expansion forming, it is possible to suppress the installation of the metal billet. As a result, the press pressure during hot expansion molding can be reduced.
[0027]
A hot billet forming metal billet according to the next invention has at least one flat surface on its side surface, and has an overhanging portion that engages with the inlet end of the forming container at the rear end in the pressing direction. It is characterized by that.
[0028]
Since the metal billet for hot expansion forming is provided with an overhanging portion at the end on the rear side in the pressing direction, the overhanging portion locks the metal billet to the container end during hot expansion forming. By this action, the restraint between the container and the metal billet becomes stronger, and the upsetting of the metal billet on the front side in the pressing direction can be suppressed. In addition, since at least one plane is provided on the side surface, an effect of bending the plane and an effect of suppressing the flow of metal also occur. Therefore, the press pressure can be kept small by these interactions. Moreover, this metal billet is provided with an overhanging portion on the rear side in the pressing direction of the metal billet in advance during manufacture. For this reason, since the process of forming an overhang | projection part in the back side of a press direction on the trunk | drum of a container before moving to a hot expansion molding process becomes unnecessary, the manufacturing process of a container can be simplified. The metal billet has a constant cross-sectional shape over the axial direction.
[0029]
The hot billet forming metal billet according to the next invention has a polygonal cross-sectional shape perpendicular to the axial direction at least on the front side in the pressing direction, and an inlet end portion of the forming container on the rear side in the pressing direction. An overhanging portion for engagement is provided.
[0030]
Since the metal billet for hot expansion forming has a protruding portion on the rear side in the pressing direction, the protruding portion locks the metal billet to the container end during hot expansion forming. By this action, the restraint between the container and the metal billet becomes stronger, and the upsetting of the metal billet on the front side in the pressing direction can be suppressed. Further, since the cross-sectional shape perpendicular to the axial direction at least on the front side in the pressing direction is formed in a polygon, an action of bending this plane and an action of suppressing the flow of metal also occur. Therefore, the press pressure can be kept small by these interactions. Moreover, this metal billet is provided with an overhanging portion on the rear side in the pressing direction of the metal billet in advance during manufacture. For this reason, since the process of forming an overhang | projection part in the back side of a press direction on the trunk | drum of a container before moving to a hot expansion molding process becomes unnecessary, the manufacturing process of a container can be simplified.
[0031]
The metal billet for hot expansion forming according to the next invention has a polygonal cross-sectional shape perpendicular to the axial direction at least on the front side in the pressing direction, and the front side in the pressing direction is gradually narrowed toward the pressing direction. At least one or more stepped portions are provided, and an overhanging portion that engages with the inlet end portion of the molding container is provided on the rear side in the pressing direction.
[0032]
Since the metal billet for hot expansion forming has a protruding portion on the rear side in the pressing direction, the protruding portion locks the metal billet to the container end during hot expansion forming. By this action, the restraint between the container and the metal billet is further strengthened, and the upsetting on the front side in the pressing direction can be suppressed. Further, since the cross-sectional shape perpendicular to the axial direction at least on the front side in the pressing direction is formed in a polygon, an action of bending each side of the polygon cross-section and an action of suppressing metal flow also occur. Furthermore, since the front side of the press is gradually reduced toward the press direction, the timing at which the metal fills the bottom of the molding container can be delayed. Therefore, the press pressure can be kept small by these interactions. Moreover, this metal billet is provided with an overhanging portion on the rear side in the pressing direction of the metal billet in advance during manufacture. For this reason, since the process of forming an overhang | projection part in the back side of a press direction on the trunk | drum of a container before moving to a hot expansion molding process becomes unnecessary, the manufacturing process of a container can be simplified. In addition, since the front side of the press is thinned in steps, molding becomes relatively easy.
[0033]
The hot billet forming metal billet according to the next invention is provided with at least one plane on at least one of the side surface on the front side in the pressing direction or the side surface on the rear side in the pressing direction, and the front side in the pressing direction is in the pressing direction. It is characterized in that at least one or more stepped portions are provided so as to become narrower stepwise, and an overhanging portion that engages with the inlet end portion of the molding container is provided on the rear side in the pressing direction.
[0034]
Since the metal billet for hot expansion forming has a protruding portion on the rear side in the pressing direction, the protruding portion locks the metal billet to the container end during hot expansion forming. By this action, the restraint between the container and the metal billet is further strengthened, and the upsetting on the front side in the pressing direction can be suppressed. Further, since at least one plane is provided on at least one of the side surfaces of the metal billet, an action of bending the plane and an action of suppressing the flow of the metal also occur. Furthermore, since the front side of the press is gradually reduced toward the press direction, the timing at which the metal fills the bottom of the molding container can be delayed. Therefore, the press pressure can be kept small by these interactions. Moreover, this metal billet is provided with an overhanging portion on the rear side in the pressing direction of the metal billet in advance during manufacture. For this reason, since the process of forming an overhang | projection part in the back side of a press direction on the trunk | drum of a container before moving to a hot expansion molding process becomes unnecessary, the manufacturing process of a container can be simplified. In addition, since the front side of the press is thinned in steps, molding becomes relatively easy.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments. Moreover, the manufacturing method of the container or cylinder which concerns on this invention is not limited to the method disclosed below. Furthermore, the constituent elements of the following embodiments include those that can be easily assumed by those skilled in the art.
[0036]
(Embodiment 1)
FIG. 1 is an explanatory view showing an example of a bottomed container according to Embodiment 1. FIG. FIG. 2 is an explanatory view showing a manufacturing process of the bottomed container 1 shown in FIG. FIG. 3 is a perspective view showing an example of a metal billet 200 used in the first embodiment. As shown in FIG. 1 (a), the bottom 1b of the bottomed container 1 according to the first embodiment is formed integrally with the body 1a, and can be seen from FIG. 1 (b). Moreover, the cross-sectional shape of the bottomed container 1 according to Embodiment 1 is circular.
[0037]
In this manufacturing method, the bottomed container 1 is manufactured by hot expansion molding using a punch. First, the metal billet used for this manufacturing process is demonstrated. The metal billet 200 is manufactured by a molten metal mold ingot or a metal ingot cutting or free forging before entering a hot expansion forming process described below. In this forging process, it is desirable to form at least the front side of the metal billet in the pressing direction into a square cross section. By doing in this way, the effect of hot expansion molding can be used more effectively. In the first embodiment, a seamless metal billet 200 is manufactured by freely forging a metal lump, but the metal billet that can be used in the present invention is not limited to this.
[0038]
As shown in FIG. 3, the cross-sectional shape of the metal billet 200 used in the present embodiment is such that the rear side in the press direction (hereinafter abbreviated as the press rear side) 200a is circular and the front side in the press direction (hereinafter referred to as the press). 200b is a square. The outer diameter of the press rear side 200a is larger than the diagonal length of the press front side 200b. The outer diameter of the press rear side 200a is substantially equal to the inner diameter of the container 300, and the diagonal length of the press front side 200b. Is shorter than the inner diameter of the barrel 300 of the molding container (FIG. 5b). In addition, the internal diameter of the trunk | drum 300 of a molding container is shown with the broken line.
[0039]
Further, in this example, a cross section 970 perpendicular to the axial direction of the metal billet 200 on the press front side 200b includes a projected image 920 of a cross section perpendicular to the axial direction of the punching punch 410 (FIG. 3). b) and (e)). In addition, the cross-sectional shape, dimension, or external shape of the metal billet 200 is not limited to this example. Other examples of billets applicable to the present invention will be described later.
[0040]
Next, the hot expansion molding process will be described. Prior to hot expansion forming, the metal billet 200 is heated to a temperature at which it is easy to perform hot expansion forming in a heating furnace (not shown). Since the heating temperature is determined by the material of the metal billet 200 and the like, it is not uniquely determined. In addition, in the carbon steel material used for the body of a cask for storing, transporting, and temporarily storing spent nuclear fuel, it is desirable to set the heating temperature to 1100 ° C to 1300 ° C. If this range is exceeded, the crystal grains become coarse and surface oxidation and decarburization occur, and the material becomes brittle and easily cracked. In the case of carbon steel, the heating temperature decreases within the above range as the carbon ratio increases. The metal billet 200 heated to a temperature at which it is easy to perform hot expansion molding in an electric furnace or the like is inserted into the barrel portion 300 of the molding container as shown in FIG.
[0041]
The metal billet 200 inserted into the barrel 300 of the forming container is installed by a large punch 400 having an outer diameter substantially equal to or larger than the outer diameter of the metal billet 200, and the metal billet 200 is pushed rearward in the press direction. The side 200a forms an overhang 201 on the container 300 (see FIG. 2 (b)). By providing this overhanging portion 201 at the end of the metal billet 200, it is possible to increase the restraining force in the axial direction of the metal billet 200 in the hot expansion forming process using a punch. And by this effect | action, the upset phenomenon of the metal billet 200 can be suppressed and the flow of the metal which goes to the direction opposite to a press direction can be reduced, Therefore The raise of press pressure can be suppressed. At the same time, the shape of the end face of the bottomed container after molding can be improved.
[0042]
Even if the protruding portion 201 is not provided on the metal billet 200, the upsetting phenomenon is suppressed by the frictional force generated between the inner wall of the barrel portion 300 of the molding container and the side surface 200a on the rear side of the metal billet 200. Can do. However, in order to further reduce the pressing pressure and obtain a more complete end surface shape, it is desirable to provide the overhang portion 201.
[0043]
After the overhang portion 201 is formed at the end of the metal billet 200, the process proceeds to a hot expansion forming process by the punching punch 410. In order to make a hole in the center of the metal billet 200, a punch 410 is first placed on the center of the end face of the metal billet 200 by a positioning guide 310 attached to the barrel 300 of the molding container (see FIG. 2 (c)). Next, the punching punch 410 is pushed in by a press machine (not shown), and the metal billet 200 is hot expanded.
[0044]
When the punching punch 410 is pushed into the metal billet 200 by the press machine, the overhanging portion 201 of the metal billet 200 is engaged with the upper end portion of the barrel portion 300 of the molding container, and the upsetting phenomenon of the metal billet 200 is suppressed. . Moreover, the metal of the thick part in the press rear side 200a of the metal billet 200 is deformed so as to be filled in the container 300 (see FIG. 2 (d)). Then, since the metal on the press rear side 200a is pressed against the inner wall of the barrel portion 300 of the forming container, the upsetting phenomenon of the metal billet 200 can be suppressed also by this action. By these actions, an increase in press pressure can be suppressed, and the shape of the end face of the bottomed container after molding can be improved.
[0045]
When the punching punch 410 is pushed into the metal billet 200, the metal immediately below the punching punch 410 becomes a hemispherical metal lump and moves to the press front side 200 b together with the punching punch 410. Because of this phenomenon, the metal billet 200 needs to have a larger cross-sectional area perpendicular to the axial direction on the press rear side 200a than on the press front side 200b.
[0046]
Further, when the punching punch 410 is pushed into the metal billet 200, due to the good plastic deformation property of the steel heated to a high temperature and the phenomenon that the metal lump is supplied from the press rear side 200a, the front of the metal billet 200 is pressed. The metal on the side 200b is deformed so as to be spread toward the inner wall side of the container 300. That is, it is hot expansion molding. When the punching punch 410 is pushed to a predetermined depth set in advance, the hot expansion molding ends there (see FIG. 2 (e)).
[0047]
Here, the kind of metal billet 200 applicable to the manufacturing method of the present invention will be described. As shown in FIG. 3 (a), a metal billet having a polygonal cross section perpendicular to the axial direction on the front side of the press can be applied to the manufacturing method of the present invention. If such a metal billet is used, the metal billet is deformed so as to be expanded toward the inner wall side of the molding container in the hot expansion molding, so that the pressing pressure can be suppressed as compared with backward extrusion or the like. In addition, although the cross section perpendicular | vertical to the axial direction of the metal billet 200 shown to Fig.3 (a) is a rectangle, it is not restricted to this.
[0048]
Furthermore, the metal billet applicable to the manufacturing method of the present invention may have the following relationship. That is, the cross section perpendicular to the axial direction on the rear side of the press has a relationship including the projected image of the cross section perpendicular to the axial direction on the front side of the press. Further, the projection image of the cross section perpendicular to the axial direction on the rear side of the press has a relationship included in the inner side of the cross section of the molding container perpendicular to the axial direction. Here, the inner shape of the cross section of the molding container perpendicular to the axial direction may be the same as the projected image of the cross section perpendicular to the axial direction on the rear side of the press. It is desirable to use a metal billet that satisfies such a relationship when forming a large and thick bottomed container.
[0049]
The projection image will be described with reference to FIGS. 3 (c) and 3 (d). Here, the projected image is represented by a broken line and the cross section is represented by a solid line. FIG. 3C shows a state in which a cross section 950 perpendicular to the axial direction on the rear side in the press direction of the metal billet includes a projection image 900 of a cross section perpendicular to the axial direction on the front side in the press direction. FIG. 3D shows a state in which a projection image 910 having a cross section perpendicular to the axial direction on the rear side in the pressing direction is included in the cross section inside 960 of the molding container perpendicular to the axial direction. FIG. 3 (e) shows the state of the punching punch in which the projection image 920 of the cross section perpendicular to the axial direction is included in the cross section 970 perpendicular to the axial direction on the front side in the pressing direction of the metal billet. Show. A projected image 920 of a cross section perpendicular to the axial direction in FIG. 3 (e) is a projected image of the punching punch.
[0050]
“Inclusion” as used in the present invention means that all of the part surrounded by the broken line representing the projected image exists inside the part surrounded by the solid line representing the cross section. In the case where there is even a part surrounded by a broken line outside a part surrounded by a solid line, it is not included in the concept of “inclusion” in the present invention. Further, when the cross-sectional shape and the projected image are the same, they are not included in the concept of “inclusion” in the present invention.
[0051]
The projected image of the punch is preferably included in a cross section perpendicular to the axial direction on the front side of the metal billet (see FIG. 3 (e)). However, the projection image perpendicular to the axial direction of the punching punch and the cross section perpendicular to the axial direction on the front side of the press of the metal billet may be the same. Further, the cross section perpendicular to the axial direction of the punching punch may include a projection image of the cross section perpendicular to the axial direction on the front side of the metal billet in the press.
[0052]
However, when the cross section perpendicular to the axial direction of the punch punch includes a projected image of the cross section perpendicular to the axial direction on the front side of the metal billet, the punch punch is formed when the cross sectional area of the punch punch increases. Since the wall thickness of the container body is reduced, the container body is easily broken during hot expansion molding. Therefore, when the cross section perpendicular to the axial direction of the punching punch includes a projection image of the cross section perpendicular to the axial direction on the front side of the metal billet, the punching punch is within the range where the container body does not break. It is necessary to suppress the cross-sectional area of.
[0053]
FIG. 4 is an explanatory view showing an example of another metal billet according to the first embodiment. In these examples, as is clear from FIGS. 4A to 4D, a cross section 950 perpendicular to the axial direction on the press rear side 200a of the metal billet 200 is perpendicular to the axial direction on the press front side 200b. The condition of including the projected image 900 of the cross section (FIG. 3 (c)) is satisfied.
[0054]
When the cross section of the press front side 200b as shown in FIGS. 4 (a) and 4 (b) is a quadrangle, the force that is mainly directed outward in the radial direction of the barrel portion 300 of the container during hot expansion molding, that is, a flat surface The side surface of the metal billet provided with is deformed by a force to bend toward the inner wall side of the barrel portion 300 of the molding container.
[0055]
FIG. 5 is a conceptual diagram showing the state of this deformation. The broken line in the figure shows the process in which the metal billet 200 expands toward the inner wall side of the barrel 300 of the molding container. When the cross section perpendicular to the axial direction is a quadrangle, the punch F is pushed in, so that a force F is applied from the center of the metal billet 200 toward the outside in the radial direction of the barrel 300 of the molding container. Since this force F bends the side surface of the metal billet 200 toward the inner wall side of the molding container, the metal billet 200 is expanded to the inner wall side of the molding container by the action of this bending. In particular, this bending action works effectively when a metal billet having a flat surface on the side surface is inserted into a forming container having a circular inner section.
[0056]
Therefore, if the metal billet is expanded by the action of the bending, the press pressure required for hot expansion molding can be reduced, and defects such as cracks generated during molding can be suppressed. Even if hot expansion molding is performed using a metal billet having a square cross section perpendicular to the axial direction and a perforated punch having a square cross section perpendicular to the axial direction, it is expanded by the above bending action. Accordingly, in this case as well, the press pressure required for hot expansion molding can be reduced, and defects such as cracks occurring during molding can be suppressed.
[0057]
When the cross section perpendicular to the axial direction of the press front side 200b as shown in FIG. 4 (c) is circular, the above effect is slightly reduced. However, the metal billet 200 is composed of the press front side 200b and the container body. There is a space between 300 inner walls. Therefore, the metal on the front side of the press expands into this space during the hot expansion molding, so that the expansion deformation of the metal billet is not constrained by the barrel portion 300 of the molding container, and the press pressure can be reduced. . Further, in this case, when the hot expansion is performed by using a punch having a square cross-sectional shape perpendicular to the axial direction, the above bending action works. For this reason, compared with the case where hot expansion molding is performed using a punch having a circular cross-sectional shape perpendicular to the axial direction, the press pressure can be reduced.
[0058]
As shown in FIGS. 4 (a), (c) and (d), the cross section perpendicular to the axial direction of the press rear side 200a is circular, and the diameter thereof is substantially equal to the diameter of the barrel 300 of the molding container. In this case, the overhang portion 201 (see FIG. 3B) formed on the trunk portion 300 of the molding container can be formed evenly. Therefore, at the time of hot expansion molding, the overhanging portion 201 can more effectively suppress the upsetting phenomenon of the metal billet 200, so that the press pressure can be kept low, and the shape of the end face of the container after molding can be reduced. Can be good.
[0059]
As shown in FIG. 4 (b), when the cross section of the press rear side 200a is a quadrangle and the diagonal length is substantially equal to the diameter of the barrel 300 of the molding container, the overhang 201 is a container. That is, it is partially formed at the upper end of the body part 300. For this reason, compared with the case where the overhang portion 201 is not provided, the effect of suppressing the upsetting phenomenon of the metal billet 200 is great, but compared with the case where the overhang portion 201 is formed over the entire circumference of the upper end of the barrel portion of the molding container. Then the effect is slightly reduced.
[0060]
Furthermore, the metal billet in which the cross-sectional shape perpendicular to the axial direction of the press front side 200b or the press rear side 200a of the metal billet 200 is formed in a pentagon or more or a triangular shape is also applied to the manufacturing method according to the first embodiment. Can do. Further, as shown in FIG. 4 (d), when the side surface of the press front side 200b is provided with at least one or more planes, this portion is hot-expanded by bending as described above. The effect of keeping it low is obtained.
[0061]
Further, when the number of planes provided on the side surface of the metal billet 200 is three or more, that is, when the cross section perpendicular to the axial direction of the metal billet 200 is a triangle or more, the effect of suppressing the pressing pressure is increased. However, when the number of the planes increases, that is, when the corners of the polygonal cross-sectional shape perpendicular to the axial direction increase, the polygonal cross-sectional shape approaches a circle, so that the effect of suppressing the pressing pressure is reduced. Therefore, it is desirable to select the number of side surfaces on the press front side 200b within a range where the effect of suppressing the press pressure is low. In addition, since the metal billet 200 has a flat surface on its side surface, the metal billet of the present invention can also be used when the cross-sectional shape perpendicular to the axial direction of the metal billet as shown in FIG. included.
[0062]
FIG. 6 is a perspective view showing another metal billet applicable to the first embodiment. The metal billet 200 is provided with a stepped portion on the press front side 200b so as to become thinner stepwise in the pressing direction. By doing in this way, the time which the metal of the press front side 200b is filled near the bottom part of the trunk | drum 300 of a shaping | molding container at the time of hot expansion shaping | molding can be delayed. Therefore, it is possible to suppress an increase in press pressure particularly in the final stage of the hot expansion molding. Moreover, since a minute flow in the pressing direction is formed by the stepped portion, the degree of forging of the molded product can be increased, and further, the shortage of forging can be prevented. Furthermore, since the change of the cross section is gradual, the manufacturing becomes easier as compared with the case where a taper described below is provided. Note that the number of the stepped portions is not limited to the above example, and can be appropriately increased or decreased depending on press conditions.
[0063]
Further, as shown in FIG. 5B, even when a taper is formed so that the press front side 200b is narrowed toward the press direction, the same operation and effect as when the step is provided on the press front side 200b can be obtained. .
[0064]
Furthermore, as shown in FIG. 6 (c), when the metal billet 200 is manufactured, an overhanging portion 201 that engages with the upper end portion of the molding container 300 may be provided in advance on the metal press rear side 200a. By doing in this way, the process which forms the overhang | projection part 201 in the press direction back side 200a of the metal billet 200 on the trunk | drum 300 of a container before hot expansion molding becomes unnecessary, and simplifies the manufacturing process of a container. be able to.
[0065]
FIG. 7 is an explanatory view showing another metal billet applicable to the first embodiment. As shown in the drawing, the metal billet 200 has a constant cross section perpendicular to the axial direction in the press direction, and an overhanging portion 201 that engages with the upper end portion of the molding container 300 is provided at one end thereof. There is a feature in the point. Even when such a metal billet 200 is used, a phenomenon in which the metal billet is placed at the time of hot expansion forming can be suppressed by the overhanging portion 201, so that an increase in press pressure can be suppressed. The cross-sectional shape of the metal billet 200 is not limited to a quadrangle, and the cross-sectional shape may be a polygon, and the side surface of the metal billet 200 may include at least one plane. The overhang portion 201 may be provided on the metal billet 200 in advance, or the overhang portion 201 may be provided after the metal billet 200 is loaded into the molding container 300.
[0066]
When the metal billet 200 is expanded and deformed so as to be spread toward the inner wall side of the container 300 (see FIGS. 2D and 2E), a frictional force is generated between the metal of the metal billet 200 and the inner wall of the container 300. appear. This frictional force is due to the fact that the metal on the front side 200b of the press moves along the inner wall of the container body 300 to the side opposite to the press direction. In the intermediate process of the hot expansion molding in the manufacturing method according to the first embodiment, this frictional force is hardly generated. However, in the final stage of the hot expansion molding, the friction force is generated because the lower part of the molding container is filled with metal. The body 300 of the molding container tends to move in the direction opposite to the pushing direction of the punch 410 by this frictional force.
[0067]
Here, when the barrel 300 of the molding container and the bottom 301 of the molding container are fixed, the metal on the front side of the press moves against the frictional force, and the final stage of hot expansion molding. Then, an extra load is required. In order to solve this problem, the first embodiment has a structure in which the barrel 300 of the molding container and the bottom 301 of the molding container can move relatively.
[0068]
With such a structure, when the barrel 300 of the molding container is about to move in the direction opposite to the pushing direction of the punch 410 due to the frictional force, the punch 410 together with the metal billet 200 to be molded is also formed. It moves in the direction opposite to the pushing direction of (Fig. 2 (e)). That is, since the relative movement of the barrel 300 of the molding container and the metal billet 200 to be molded hardly occurs, an increase in load in the final stage of the hot expansion molding can be suppressed.
[0069]
In the present embodiment, not only the barrel 300 of the molding container and the bottom 301 of the molding container can move relative to each other, but also the barrel 300 of the molding container is divided to form the entire metal billet 200. The barrel 300 of the container is movable. By doing in this way, even if it is a case where a bottomed container long in the direction of an axis is formed, an increase in load in the final stage of hot expansion molding can be controlled.
[0070]
FIG. 8 is a cross-sectional view showing a divided portion of the trunk portion 300 of the molding container used in the first embodiment. As shown in FIG. 5A, the dividing portion of the molding container body 300 has a structure in which the dividing portions overlap each other, and the molding container barrels 300a and 300b relatively move during hot expansion molding. It may be. Also, as shown in FIG. 4B, a concave portion is formed in the barrel portion 300a of one molding container, and a convex portion is provided in the barrel portion 300b of the other molding container to combine the two. The structure may be such that the barrel portions 300a and 300b of the molding container move relatively during the intermediate expansion molding.
[0071]
In the present embodiment, the body portion 300 of the pre-molding container is divided into two parts, but the number of divisions can be appropriately changed according to the height of the metal billet 200. Further, only the barrel 300 of the molding container is divided, or the barrel 300 of the molding container and the bottom 301 of the molding container can be relatively moved without dividing the barrel 300 of the molding container. However, there is an effect of suppressing an increase in load during hot expansion molding.
[0072]
When the punch 410 is pushed to a predetermined depth set in advance, the hot expansion molding ends there (FIG. 2 (e)). In addition, as shown in FIG. 2 (e ″), if a cylindrical spacer 302 is placed in place of the bottom portion 301 of the molding container and the bottom portion of the metal billet 200 is punched, a cylindrical object can be molded by this manufacturing method. . When manufacturing a thick container with a length of several meters in the axial direction by the above manufacturing method, the press pressure can be reduced to a fraction of the conventional pressure due to the effect of the hot expandable diameter, so it can be manufactured with conventional equipment. . Moreover, since the bottomed container which united the bottom part and the trunk | drum can be manufactured by one process, it does not require a labor for manufacture and is suitable for mass production.
[0073]
The metal billet 200 that has been subjected to hot expansion forming is cooled to room temperature while performing natural cooling, forced cooling, or controlled cooling. Then, in order to adjust the shape of the end face, or to finish the outer shape or inner shape of the molded container to a desired dimension, cutting or the like may be performed.
[0074]
Next, the result of the specific example which manufactured the bottomed integral cylindrical container by the said method is shown. As a comparative example, a result of manufacturing a bottomed integrated cylindrical container by applying the Erhardt perforation method which has been conventionally used is also shown.
[0075]
Both the specific example and the comparative example were molded using a cylindrical container having an inner diameter of 943 mm. As the material of the cylindrical container, carbon steel having a carbon (C) ratio of 0.1% is used, but stainless steel may be used. First, the carbon steel metal billet was heated to 1250 ° C., and then forged into a metal billet having a different cross-sectional shape with a substantially T-shaped axial cross section by a free forging method. The front side of the metal billet has a square cross section with a diagonal length of 875 mm which is smaller than the inner diameter of the molding container, and the axial length is 1896 mm. The rear side of the press has a circular cross section having an outer diameter of 928 mm, which is substantially equal to the inner diameter of the molding container, and the length in the axial direction is 574 mm. The metal billet was heated again to 1250 ° C. and then charged into a molding container, and the center of the workpiece was hot-expanded with a punch to form an elongated cup-shaped cylindrical container having a length of 2420 mm and a thickness of 165 mm.
[0076]
On the other hand, in the comparative example, the same carbon steel as that of the specific example is used as the material of the cylindrical container, and after heating the metal billet to 1250 ° C., a square shape having the same cross-sectional shape over the entire length in the axial direction by a free forging method. Forged into a metal billet. The cross-sectional shape of this metal billet is a square, and its diagonal length is 928 mm, which is substantially equal to the inner diameter of the molding container. The axial length is 2470 mm. This metal billet was again heated to 1250 ° C. and then subjected to hot expansion molding to produce a cylindrical container having the same size as the above specific example.
[0077]
Table 1 shows the evaluation results of the forming load and the end face shape by the both press methods. As is clear by comparing the two, it can be seen that according to the manufacturing method of the present invention, the press molding load is small and the product yield is high as compared with the conventional manufacturing method. In addition, since there were almost no defects in the end face shape found in the conventional manufacturing method, it was possible to finish the product with simple processing even after hot expansion molding.
[Table 1]

[0078]
Here, an example in which the outer side and the inner side of the molded bottomed container are cut for use in a radioactive substance storage container such as a cask or a canister will be described. FIG. 9 is a schematic view showing an apparatus for cutting the outside of a bottomed container that has been hot-expanded. The bottomed container 1 is placed on a rotation support base 154 provided with a roller and can freely rotate in the circumferential direction. A fixed table 141 is provided outside the bottomed container 1, and a movable table 142 that slides on the fixed table 141 in the axial direction of the bottomed container 1 is provided. A cutting tool 160 is attached to the movable table 142, and the outer periphery of the bottomed container 1 is cut by the cutting tool 160.
[0079]
A roller 161 attached to the rotation support base 154 is connected to a motor 162. The rotation of the motor 161 is transmitted to the bottomed container 1 via the roller 161 and rotates the bottomed container 1. When the motor 161 rotates and the bottomed container 1 starts to rotate in the direction of the arrow in the figure, the movable table 142 is moved in the axial direction of the bottomed container 1 by the servo motor 157 and the ball screw 158 provided at the end of the fixed table 141. The outer periphery of the bottomed container 1 is cut by the cutting tool 160 attached to the movable table 142. Further, if the outer periphery is cut by a face mill or the like to provide a flat surface, a container with a bottom having a polygonal shape as well as a circular shape can be formed in addition to a circular section in the axial direction.
[0080]
Next, an example of cutting the inside of the molded bottomed container will be described. FIG. 10 is a schematic view showing an apparatus for processing the inside of the bottomed container. The processing apparatus 140 includes a fixed table 141 that penetrates the body body 101 and is placed and fixed inside the bottomed container 1, a movable table 142 that slides on the fixed table 141 in the axial direction, and a movable table 142. It comprises a saddle 143 positioned and fixed above, a spindle unit 146 comprising a spindle 144 and a drive motor 145 provided on the saddle 143, and a face mill 147 provided on the spindle shaft. Further, on the spindle unit 146, a reaction force receiver 148 in which a contact portion is formed in accordance with the inner shape of the bottomed container 1 is provided. The reaction force receiver 148 is detachable and slides in the direction of the arrow in the figure along a dovetail groove (not shown). The reaction force receiver 148 has a clamp device 149 for the spindle unit 146 and can be fixed at a predetermined position.
[0081]
Further, a plurality of clamping devices 150 are attached in the lower groove of the fixed table 141. The clamp device 150 includes a hydraulic cylinder 151, a wedge-shaped moving block 152 provided on the shaft of the hydraulic cylinder 151, and a fixed block 153 that abuts the moving block 152 on an inclined surface. The part side is attached to the groove inner surface of the fixed table 141.
[0082]
When the shaft of the hydraulic cylinder 151 is driven, the moving block 152 comes into contact with the fixed block 153, and the moving block 152 moves slightly downward (indicated by a dotted line in the figure) due to the wedge effect. Thereby, since the lower surface of the moving block 152 is pressed against the inner surface of the cavity 102, the fixing table 141 can be fixed inside the bottomed container 1.
[0083]
Further, the bottomed container 1 is placed on a rotation support base 154 made of a roller, and is rotatable in the radial direction. Further, by attaching a spacer 155 between the spindle unit 146 and the saddle 143, the height of the tool 147 on the fixed table 141 can be adjusted. The thickness of the spacer 155 is the same as the dimension of one side of the square pipe constituting the basket. The saddle 143 moves in the radial direction of the trunk body 101 by rotating a servo motor 156 provided on the movable table 142. Movement of the movable table 142 is controlled by a servo motor 157 and a ball screw 158 provided at the end of the fixed table 141. In addition, since the shape inside the bottomed container 1 changes as processing proceeds, it is necessary to change the reaction force receiver 148 and the moving block 152 of the clamp device 150 to those having an appropriate shape.
[0084]
FIG. 11 is an explanatory view showing an example of a processing method inside the bottomed container 1. First, the fixing table 141 is fixed at a predetermined position inside the bottomed container 1 by the clamping device 150 and the reaction force receiver 148. Next, as shown in FIG. 6A, the spindle unit 146 is moved at a predetermined cutting speed along a fixed table (not shown), and the inside of the bottomed container 1 is cut by the tool 147. When the cutting at the position is completed, the clamp device 150 is removed and the fixed table 141 is released. Next, as shown in FIG. 4B, the trunk body 101 is rotated 90 degrees on the rotation support base 154, and the fixing table 141 is fixed by the clamp device 150. And it cuts with the tool 147 like the above. Thereafter, the same process as described above is further repeated twice.
[0085]
Next, the spindle unit 146 is rotated 180 degrees, and the cavity 102 is sequentially cut as shown in FIG. 11 (c). Also in this case, the processing is repeated while rotating the trunk body 101 by 90 degrees as described above. Thereafter, as shown in FIG. 11 (d), a spacer 155 is attached to the spindle unit 146 to raise the position of the spindle unit. And the tool 147 is sent to an axial direction in the said position, and the inside of the bottomed container 1 is cut. By repeating this while rotating 90 degrees, the shape necessary for inserting a square pipe (not shown) for storing spent nuclear fuel is almost completed. In addition, it can process also with a general horizontal centering machine and a vertical type intermediate boring machine without depending on an exclusive machine.
[0086]
In the above description, the example in which the bottomed container 1 is laterally cut outside and inside is described. However, the bottomed container 1 is vertically cut and the outside and inside of the container are cut by the processing apparatus described below. May be.
[0087]
Specifically, the processing apparatus includes a rotary table for placing and rotating a bottomed container to be processed, a crane for placing the bottomed container on the rotary table, and moving the rotary base from the rotary table after processing, a base A movable table placed on the movable table, a saddle that can be moved on the movable table in a direction perpendicular to the movable direction of the movable table, a column that supports the arm that is placed on the saddle and moves up and down, and a column. It is attached to the vertical direction so that it can be moved up and down, is equipped with an attachment with a tool attached to the tip, and is provided with an arm that moves up and down with respect to the workpiece to process the workpiece. This processing apparatus can cope with various processes such as milling and drilling by changing the attachment attached to the tip of the arm.
[0088]
When processing the bottomed container is started, the bottomed container to be processed is placed on the rotary table by the crane, and after centering, the bottomed container is fixed on the rotary table. When the outside of the bottomed container is cut into a cylindrical shape, a cutting tool is attached to the attachment attached to the arm, and the bottomed container is cut with the cutting tool while rotating the rotary table at a predetermined rotation speed. Here, since the column to which the arm is attached is placed on the saddle, the arm can be moved by moving the saddle and the movable table. Therefore, an arbitrary cutting amount can be set by moving the arm to an arbitrary position. Further, since the arm can move up and down, the entire side surface of the bottomed container can be cut by moving this arm over the entire axial direction of the bottomed container. Since these movements require accuracy, it is desirable to move the movable table or the like by converting the rotational movement of a servo motor or stepping motor into a linear movement using a ball screw or the like.
[0089]
When cutting the outer periphery of a bottomed container having a circular outer shape in the radial direction and processing it into a polygonal column shape such as an octagonal column, for example, an attachment for a face mill is attached to the arm and the bottom container is removed by face milling. Cut the sides. When the arm is moved up and down to cut one surface over the entire axial direction of the bottomed container, the rotary table is rotated 45 degrees to process the next side surface. If this operation is repeated eight times, a bottomed container having an octagonal outer diameter in the radial direction can be manufactured. In this way, a bottomed container having an arbitrary polygonal cross section can be manufactured.
[0090]
When a bottomed container is used as a cask for storing spent nuclear fuel, it is desirable that the inner shape of the bottomed container be a shape that matches at least a part of the outer periphery of the basket that stores the spent nuclear fuel assembly. This is because the basket can be easily inserted and fixed in the container. An example of such a cross-sectional shape is as shown in FIG. In order to form the inside of the bottomed container into such a shape, the attachment attached to the arm is changed to that for an end mill, for example, and the corners in the cross section are processed into a stepped shape.
[0091]
First, the saddle and the movable table are moved to move the arm over the bottomed container placed on the rotary table. Next, the arm is lowered and an attachment with an end mill is inserted into the bottomed container to position the end mill. Thereafter, the inside of the bottomed container is cut by giving a predetermined cutting amount. Cutting is performed several times, and once a predetermined shape is obtained, the first cutting is completed. When the necessary stepped shape is obtained at one corner, the turntable is rotated 90 degrees to process the next corner. When this operation is repeated four times, a cask bottomed container having a radial cross-sectional shape as shown in FIG. 15D can be manufactured.
[0092]
In addition, when the inside of the bottomed container is cut, there is no escape space for cutting waste and cutting oil, so that cutting cannot be performed during the machining. For this reason, for example, it is desirable to remove cutting waste and the like from the inside of the bottomed container being processed by discharge means such as a vacuum pump.
[0093]
When the bottomed container is cut vertically, the processing of cutting scraps and the like is required as compared with the case where the container is placed horizontally, but the influence of deformation due to gravity can be reduced. Note that if the processing apparatus is configured upside down, the bottomed container is processed with the opening facing down, so that chips and the like can be easily discharged when the inside of the bottomed container is cut.
[0094]
Next, an example in which the bottomed container manufactured by the method of the present invention is applied to a cask that is a used nuclear fuel storage container will be described. FIG. 12 shows a cask according to an embodiment of the present invention, in which (a) is an axial sectional view and (b) is a radial sectional view. The cask 100 includes a bottomed container 1 having a basket 3 therein, a neutron shielding material 2 such as a resin or silicone rubber provided outside the bottomed container 1, and an outer cylinder 4 serving as an outer surface of the cask 100. It is composed of The bottomed container 1 is formed by molding the inner side and the outer side by the above-described cutting process.
[0095]
A primary lid 5 and a secondary lid 6 are provided at the top of the bottomed container 1, and a resin 7 for shielding neutrons is sealed in the secondary lid 6. The bottomed container 1 has a bottomed cylindrical shape formed by punching drawing and is made of carbon steel or stainless steel having a γ-ray shielding function.
[0096]
The neutron shielding material 2 is a polymer material containing a large amount of hydrogen and has a neutron shielding function. Further, a shielding body 9 enclosing a neutron shielding material 8 such as resin or silicone rubber is attached to the bottom of the bottomed container 1. The basket 3 is configured by arranging cells for containing spent nuclear fuel assemblies (not shown) in a lattice shape, and is made of a composite material of boron and aluminum.
[0097]
In addition, a metal gasket is provided between the primary lid 5 and the secondary lid 6 and the bottomed container 1 in order to ensure sealing performance as a pressure vessel. A plurality of copper internal fins 10 that conduct heat are welded between the bottomed container 1 and the outer cylinder 4, and the neutron shielding material 2 is in a fluidized state in a space formed by the internal fins 10. Injected and exothermic solidified. The primary lid 5 and the secondary lid 6 are made of carbon steel or stainless steel having a γ-ray shielding function.
[0098]
Since the cask 100 uses the bottomed container 1 with a bottom, it is possible to save the labor of manufacturing as compared with the case where a conventional bottom plate is welded. In addition, since the bottom plate is conventionally welded to the bottomed container, the hermeticity of the part is affected by the quality of the welding. There are very few problems of sealing in the part. In realizing the cask 100 of the present invention, the shape and material of the basket 3 in the bottomed container 1, the filling state of the neutron shielding material 2, the number and positions of the internal fins 10, etc. are shown in FIG. It is not limited to the example.
[0099]
The manufacturing method of the bottomed container according to the first embodiment is suitable for manufacturing a so-called thick container having a large thickness with respect to the diameter of the cylinder. Furthermore, the manufacturing method of the present invention is suitable for manufacturing a container having an axial length and an inner diameter of 1: 1 or more among so-called thick containers. If this ratio is exceeded, in general hot working, the press pressure increases as the forming progresses, but the manufacturing method according to the present embodiment does not increase the press pressure significantly at the beginning and end of processing. is there. Specifically, the manufacturing method according to the present embodiment is, for example, when manufacturing a cask or the like that is a large bottomed container having a thickness that is thick with respect to the diameter and that has an axial length of several meters. Especially suitable for.
[0100]
Conventionally, in order to manufacture such a large and thick-walled bottomed container, a tens of thousands of ton scale press machine has been required. However, when such a so-called thick large bottomed container is manufactured by the manufacturing method according to the present invention, the press pressure is only about 10,000 tons, so that an existing large press can be used without using a tens of thousands ton press. Can be molded by machine. Moreover, since the container after molding is excellent in the end face shape, and the surface and internal defects are hardly generated, the modification after molding becomes almost unnecessary. In addition, the manufacturing method of this invention is not restricted to such a thick large bottomed container, The canister which is a radioactive substance storage container with comparatively thin thickness can also be manufactured.
[0101]
In addition, according to the manufacturing method of the present invention, a cylinder for a large press machine, a container for a chemical plant, a reactor container for an oil refining plant, an ammonia synthesis tank, a container for a heat exchanger, a pressure vessel such as a boiler, or a water turbine for hydroelectric power generation. A casing for a large rotating device to be housed, a trunk of a submarine or a submarine can be manufactured. In addition to carbon steel, materials that can be used in the method of the present invention include non-ferrous metals such as nickel alloys, aluminum alloys, copper alloys, and magnesium alloys, as well as ferrous materials such as stainless steel and low alloy steel.
[0102]
(Embodiment 2)
FIG. 13 is a perspective view showing a bottomed container according to Embodiment 2 of the present invention. The bottomed container 1 shown in FIG. 13 is characterized in that both its outer shape and inner shape are octagonal. Further, at least one of the outer shape and the inner shape of the container may be a polygon. Since the bottom container of the cask, which is the radioactive substance storage container, contains a basket that supports the assembly of fuel rods, especially in the cask, the inner shape of the bottom container is formed into a shape that matches the basket. Is preferred. Accordingly, the inner shape of the cask is preferably a polygonal shape rather than a circular shape. When the inner shape of the cask is a polygon, it is advantageous in terms of size and weight to make the thickness of the cask barrel as uniform as possible. desirable. This bottomed container can meet such a demand.
[0103]
FIG. 14 is a cross-sectional view showing a container body and a punch for manufacturing the bottomed container according to the second embodiment. The barrel 300 of the molding container has a substantially octagonal cross-sectional shape inside, and the outer shape of the punching punch 410 is also a substantially octagonal shape. If the barrel 300 of the molding container and the perforated punch 410 are used in the hot expansion molding method described in the first embodiment, an increase in load during the hot expansion molding is suppressed, and processing after the molding is completed. It is possible to manufacture a bottomed container having a polygonal cross section that suppresses surface defects of an object and has an excellent end face shape.
[0104]
FIG. 15 is a cross-sectional view perpendicular to the axial direction showing an example of a bottomed container that can be formed by the manufacturing method according to the second embodiment. A bottomed container having such a cross-sectional shape can be formed by appropriately changing the cross-section of the forming container barrel and the outer shape of the perforated punch. In particular, it is desirable that the punching punch 410 forming the inner shape of the cask is appropriately changed in accordance with the shape of the basket for storing the spent nuclear fuel. For example, if a perforated punch having an outer cross-sectional shape as the outer shape as shown in FIG. 4D is used, an inner shape matching the shape of the basket can be formed.
[0105]
FIG. 16 is an axial sectional view showing an example of a bottomed container that can be formed by the manufacturing method according to the second embodiment. These containers can be molded by matching the inner shape of the bottom of the molding container 300 and the tip shape of the perforated punch 410 with the shape of the bottom of the bottomed container. The container shown in FIG. 4D may be formed with a hole in the bottom after forming, or may be formed with a punch having a protrusion at the tip. The container formed in this way can be used for a container in which the bottom part formed integrally with the body part requires a curved surface instead of a flat surface. For example, the present invention can be applied to a casing for a large-sized rotating device that houses a water turbine for hydroelectric power generation.
[0106]
(Embodiment 3)
FIG. 17 is an axial sectional view showing a bottomed container according to Embodiment 3. The bottomed container 1 is characterized in that the body and the bottom are formed integrally, and at the same time, a spotted portion is formed on the bottom of the container. Conventionally, the bottom provided with a counterbore on a thick cylinder was attached by welding, but this manufacturing method requires a welding process and a heat treatment process after welding in addition to the process of providing a counterbore on the bottom. There was a problem that it took time and effort. According to the method for manufacturing a bottomed container according to the present invention, the bottom provided with the counterbore portion in one step can be formed integrally with the body, and thus there is an advantage that the manufacturing becomes very easy.
[0107]
FIG. 18 is an explanatory view showing a method of providing a counterbore 800 in the bottomed container. As shown in FIG. 2A, before the punch 410 is pushed in and subjected to hot expansion molding, a cylinder 302, which is a cylindrical member, is provided in advance on the bottom 301 of the molding container. Here, the counterbore 800 can be formed only by the cylinder 302, but an annular metal plate 303 may be previously placed on the upper portion of the cylinder 302 in order to facilitate the removal of the cylinder 302 after the metal billet 200 is formed ( (See (a) of the figure). The annular metal plate 303 has a slightly larger radial width than the radial width of the cylinder 302. By doing in this way, after shape | molding the metal billet 200 to a bottomed container, the cylinder 302 can be easily removed. In this case, the annular metal plate 303 is fitted into the bottom after the bottomed container is formed.
[0108]
When the counterbore 800 is formed only by the cylinder 302, it is desirable that the diameter of the cylinder on the side where the cylinder contacts the metal billet 200 be smaller than the diameter on the side where the cylinder contacts the bottom 301 of the molding container 300. That is, it is desirable to provide the cylinder 302 with a taper so that the diameter of the cylinder 302 increases in the pressing direction. By doing in this way, it becomes easy to remove the cylinder 302 from the metal billet 200 after hot expansion molding.
[0109]
The metal billet 200 is placed in the container body 300 and placed on the cylinder 302 and the annular metal plate 303 (FIG. 18 (b)), and the punch 410 is pushed into the billet 200 to form a bottomed container. It is subjected to an extended molding (FIG. 18 (c)). At the bottom of the metal billet 200 thus formed, an annular groove is formed by the cylinder 302 and the annular metal plate 303 as shown in FIG. 18 (d). Since the annular groove is merely provided as it is, the columnar portion which is a columnar portion existing inside the annular groove is cut by a cutting means (not shown) such as a gas burner in order to form the counterbore 800. To do. In this way, a bottomed container having a counterbore 800 at the bottom can be manufactured (FIG. 18 (e)). The counterbore 800 may be finished by cutting or the like as necessary.
[0110]
Further, as shown in FIG. 18 (b ′), even if the column 304 is used instead of the cylinder 302, the spot portion 800 can be formed on the bottom of the bottomed container. In this case as well, the metal plate 305 can be placed on the cylinder 304 and molded (FIG. 18 (c ′)). Unlike the case where the cylinder 302 is used, when the column 304 is used, a counterbore 800 can be formed at the bottom of the bottomed container (FIG. 18 (e ′)). For this reason, the step of cutting the cylindrical portion shown in FIG. 4D is not necessary, but on the other hand, a larger pressing pressure is required than when the cylinder 302 is used. Therefore, it is desirable to determine which one of the cylinder 302 and the column 304 is used in consideration of the performance of the press machine, the size of the bottomed container to be manufactured, and the like.
[0111]
When the counterbore 800 is formed only by the column 304, it is desirable to provide a taper that increases toward the front side in the pressing direction. That is, it is desirable that the cylinder 304 has a trapezoidal cylinder in the axial direction. By doing in this way, it becomes easy to remove the cylinder 302 from the metal billet 200 after hot expansion molding.
[0112]
The counterbore 800 having a desired cross-sectional shape can be formed by changing the cross-sectional shape perpendicular to the axial direction of the cylinder 302 and the column 304. For example, a counterbore portion 800 having a polygonal inner surface shape can be formed by making the cross-sectional shape perpendicular to the axial direction a polygonal shape. By doing in this way, since the spot part according to the external shape of the bottomed container can be formed, the radial thickness in the spot part can be kept constant.
[0113]
FIG. 19 is an axial sectional view showing an example of a bottomed container that can be formed by the manufacturing method according to the present invention. The bottomed container 1 shown in FIGS. 19 (a) and 19 (b) can be formed by appropriately selecting the diameter of a cylinder or a column in the above description. FIG. 5C shows an example in which a two-step counterbore 800 is provided at the bottom. In order to provide the two-step counterbore part 800, for example, it can be formed by placing a forming jig having a convex shape in the axial direction on the bottom of the metal billet 200, which is formed by stacking two cylinders having different diameters. . Moreover, it can also shape | mold by installing two cylinders from which a diameter and height differ in the bottom of the metal billet 200. FIG. Further, a step portion may be provided on the outer side surface of the cylinder with respect to the axial direction.
[0114]
(Embodiment 4)
FIG. 20 is an axial sectional view showing a bottomed container according to Embodiment 4 of the present invention. This bottomed container 1 is characterized in that, in the manufacturing method shown in Embodiment 1, the overhang portion 201 (see FIG. 2 (b)) formed before hot expansion molding is used as it is as a flange of the container. There is. The cask, which is a used nuclear fuel storage container, encloses a helium gas of several atmospheres between the primary lid and the secondary lid, so that a large force is applied to the attaching portion of the secondary lid. In addition, since the secondary lid may be subject to a drop impact, the flange portion, which is the attachment portion of the secondary lid, is required to have a strong structure. In the container according to the present invention, the flange is formed integrally with the body, and since the diameter is larger than the diameter of the body, it is easy to take means such as arranging bolts in two rows. Therefore, the secondary lid can be more firmly fixed.
[0115]
In the conventional cask, since the flange portion is separately manufactured and welded to the cask body, it takes time and effort. According to the manufacturing method of the present invention, a thick-walled container with a bottom having an excellent end surface shape can be manufactured, so that the overhang portion 201 (see FIG. 2 (b)) formed on the end surface of the container is hardly processed and the flange is formed. Available as Therefore, the welding and post-weld heat treatment steps can be omitted, and the manufacturing process can be simplified. In FIG. 20, the overhang portion 201 (see FIG. 2 (b)) formed before the hot expansion forming is used as the flange of the container as it is, but this overhang portion 201 is cut by cutting or the like. It is also possible to process the inside of the removal container opening to form an overhanging flange that has been used so far. Also in this case, since the flange portion and the body are integrally formed, it is possible to sufficiently ensure the strength and the sealing performance.
[0116]
(Embodiment 5)
Next, another method for manufacturing the bottomed container 1 will be described. FIGS. 21 to 26 are explanatory views showing manufacturing steps of the bottomed container 1 of the cask 100 shown in FIG. The bottomed container 1 is formed by combining an upsetting process and a punching and drawing process.
[0117]
First, a ring-shaped first die 21, second die 22, and third die 23 are stacked on a slide table 20 of a press machine (not shown), and the first die 21 to the third die 23 have a first one. The pressurizing table 24, the second pressurizing table 25, and the third pressurizing table 26 are arranged to constitute a mold ((a) of FIG. 21). A punching punch 27 is located on the upper surface of the metal billet W. This punching punch 27 is pressurized by a stem 28 attached to the punch of the press machine (FIG. 21 (b)). The metal billet W is installed in the first die 21. The metal billet W is made of low carbon steel or stainless steel formed by vacuum casting, and has a truncated cone shape whose upper surface is circular and whose lower surface is smaller than the upper surface (the inclination angle is not shown). At the time of pressure processing, the metal billet W is heated within a range of 1000 ° C to 1200 ° C. The heating is performed in an electric furnace and is placed on the slide table 20 in a red state. Here, between the first die 21 and the metal billet W, the above-described cylinder 302 and the annular metal plate 303 (see FIG. 18 (a)) may be provided, and a spotted portion may be formed at the bottom.
[0118]
Next, when the metal billet W is installed, the punching punch 27 is pressurized to perform upsetting (FIG. 21 (c)). Since the inner end portion of the first die 21 has an opening shape, the material flows between the punching punch 27 and the opening portion 21a of the first die, and the metal billet W is deformed into a dish shape. Subsequently, the stem 28 is lifted together with the first die 21 using the lifting jig 29 ((d) in FIG. 21), the slide table 20 is moved and carried out, and the first pressure table 24 is removed ((21st) (E) of the figure).
[0119]
When the metal billet W is lifted together with the first die 21, the spacer 30 is placed on the second die 22 in this state ((a) of FIG. 22). Subsequently, the slide table 20 is moved to carry in the mold (FIG. 22 (b)), the punching punch 27 is pushed down as it is, and the punching and drawing process is performed by the first die 21 (FIG. 22 (c)). . As a result, when the metal billet W passes through the first die 21, the top plate-like portion is squeezed, becomes a cup shape, and is positioned in the second die 22. Next, the stem 28 and the hanging jig 29 are retracted upward, the slide table 20 is moved, the metal billet W and the mold are carried out, and the spacer 30 is removed ((d) in FIG. 22).
[0120]
In this state, the punching punch 27 remains at the bottom of the cup-shaped metal billet W (FIG. 23 (a)). Next, with the spacer 30 removed, the stem 28 is lowered and pressurized by the punching punch 27 ((b) of FIG. 23). As a result, the metal billet W is further installed, the material flows from between the opening 22a of the second die 22 and the punching punch 27, and the metal billet W is deformed. Subsequently, the second die 22 is lifted together with the metal billet W using the lifting jig 29 ((c) of FIG. 23). In this state, the slide table 20 is moved to carry out the mold, and the second pressure table 25 is removed ((d) in FIG. 23).
[0121]
Next, a spacer 31 is placed on the third die 23 ((a) of FIG. 24). Subsequently, the slide table 20 is moved to carry in the mold (FIG. 24 (b)), the punching punch 27 is pushed down as it is, and the punching and drawing process is performed by the second die 22 (FIG. 24 (c)). . Thereby, when the metal billet W passes through the second die 22, the abdomen is squeezed into a cup shape. Next, the stem 28 and the hanging jig 29 are retracted upward, the slide table 20 is moved, the metal billet W and the mold are carried out, and the spacer 31 is removed ((d) in FIG. 24). In this state, the punching punch 27 remains at the bottom of the metal billet W having a cup shape.
[0122]
Next, the slide table 20 is moved so that the metal billet W is positioned below the stem 28 (FIG. 25 (a)), the stem 28 is lowered and the metal billet W is pressurized by the punching punch 27 (25th). (B) of the figure). As a result, the metal billet W is further installed, and the material flows from between the opening 23a of the third die 23 and the punching punch 27, and the metal billet W is deformed. Subsequently, the third die 23 is lifted together with the metal billet W using the lifting jig 29 ((c) in FIG. 25). In this state, the slide table 20 is moved to remove the third pressure table 26 ((d) in FIG. 25).
[0123]
Next, the spacer 32 is installed on the slide table 20 ((a) of FIG. 26). Subsequently, the slide table 20 is moved to carry the spacer 32 (FIG. 26 (b)), the punching punch 27 is pushed down as it is, and the punching and drawing process is performed by the third die 23 (FIG. 26 (c)). ). Thereby, when the metal billet W passes through the third die 23, the abdomen is squeezed. Next, the stem 28 and the hanging jig 29 are retracted upward, the slide table 20 is moved, the metal billet W is carried out, and the spacer 32 is removed ((d) in FIG. 26). In this state, the perforated punch 27 remains at the bottom of the metal billet W having a cup shape, but is used as the bottom of the bottomed container 1 as it is. It is also possible to use the punching punch 27 after removing it. Further, when the slide table 20 is moved and the spacer 32 is carried in (FIG. 26 (b)), a cylindrical spacer 302 (see FIG. 2 (e ″)) is provided inside the spacer 32 so as to perforate. If the bottom of the metal billet W is punched by the punch 27, the cylindrical container can be formed also by this method.
[0124]
When the above molding is completed, a predetermined heat treatment is performed to machine the inner surface of the bottomed container. The bottomed container 1 thus molded has a cross-sectional reduction rate from the metal billet W of about 40%. Moreover, compared with the case where a bottomed container is formed by normal backward extrusion molding, the bottom portion of the bottomed container becomes thicker and the cask weight is increased in comparison with the case of backward extrusion molding. Further, a press machine having a large pressure is required, and it may not be possible to manufacture depending on the scale of the bottomed container. On the other hand, according to the manufacturing method according to this embodiment, since the molding is performed by combining the upsetting and the punching-out drawing as described above, the pressure at the time of upsetting or drawing may be small. For this reason, it becomes possible to shape | mold using the large sized press processing machine conventionally used.
[0125]
FIG. 27 is an explanatory view showing another method of manufacturing the above-mentioned bottomed container. In the above manufacturing method, as described above, the cylindrical punch punch 27 and the pressurizing bases 24 to 26 and the inner circular ring-shaped dies 21 to 23 are used. The shape is not limited. For example, as shown in FIG. 5B, when the outer shape of the bottomed container 1 is an octagon, the internal shapes of the first die 21b to the third die may be an octagon. In this case, the pressure table 24b installed in the die is also octagonal.
[0126]
Further, when the inner shape of the bottomed container 1 is an octagon, the perforated punch 27c may be an octagonal column as shown in FIG. The metal billet W in this case has an octagonal frustum shape (details of the taper angle are not shown). Furthermore, when the inner shape of the bottomed container 1 is stepped, the perforated punch 27d may be a stepped prism as shown in FIG. Although not shown, when the inner shape of the bottomed container is octagonal, the die 21b shown in FIG. 5B and the punching punch 27c shown in FIG. Moreover, even if it is not an octagon, according to the manufacturing method of the said invention, it can shape | mold similarly to the above by changing shapes, such as a punching punch and a die. The punching punches 27c and 27d shown in FIG. 27 can also be applied to the manufacturing method according to the first embodiment.
[0127]
FIG. 28 is an explanatory view showing an embodiment of a different manufacturing method. This manufacturing method is realized by installing the stem 51 on the slide table 52 of the press machine, attaching the punch punch 53 to the top of the stem 51, and attaching the pressurizing table 54 to the punch 55 of the press machine. That is, as shown in FIG. 5A, the metal billet W is placed on the punching punch 53 and the punch 55 of the press machine is lowered to perform the upsetting process of the metal billet W by the first die 56.
[0128]
Next, when the lower end of the metal billet W is deformed into a dish shape, the punch 55 is retracted and carried out together with the metal billet W (not shown). Then, a plurality of spacers 57 are placed on top of the first die 56 and are carried below the punch 55. Further, the pressure table 54 is removed from the punch 55 in advance. When the punch 55 is lowered and pressed in this state, the metal billet W is squeezed by the first die 56 as shown in FIG. The first die 56 is retracted as it is.
[0129]
Next, the metal billet W is carried out in the same manner as described above, the spacer 57 is removed, the pressurizing table 54 is attached, and the metal billet W is carried again below the punch 55 (not shown). A second die 58 is attached to the punch 55 side. In this state, the punch 55 is lowered, and the metal billet W is placed and pressurized (FIG. 3C). Subsequently, after the metal billet W is once carried out, a plurality of spacers 59 are installed on the second die 58 and the pressurizing table 54 is removed and carried in again. When the punch 55 is lowered and pressurized in this state, the abdomen of the bottomed container 1 is squeezed as shown in FIG. The second die 58 retreats as it is.
[0130]
Subsequently, similarly to the above, the metal billet W is carried out, the spacer 59 is removed, and it is carried again below the punch 55 (not shown). A third die 60 and a pressure table 54 are attached to the punch 55 side. When the punch 55 is lowered in this state and the metal billet W is pressurized, the metal billet W is further deformed as shown in FIG. Then, once the metal billet W is carried out, a plurality of spacers 61 are installed on the third die 60 and the pressurizing table 54 is removed and carried in again. When the punch 55 is lowered and pressurized in this state, the abdomen of the bottomed container 1 is squeezed as shown in FIG. The third die 60 is retracted downward as it is. The materials that can be used in the method of the present invention include non-ferrous metals such as nickel alloys, aluminum alloys, copper alloys, and magnesium alloys in addition to ferrous materials such as carbon steel, stainless steel, and low alloy steel.
[0131]
Specific molding conditions will be described. When this is heated to 1000 ° C. using a low billet steel billet and the strain rate is 0.1 to 1 s, the deformation resistance is 1.5 to 3 kgf / mm. ² It becomes. For example, assuming that the length of 1 m is punched out in 1 minute and the outer diameter is reduced from 2500 mm to 2200 mm with a 30-degree die, if the inner diameter is 1420 mm, the strain is
ln ((2500 ² -1420 ² ) / (2200 ² -1420 ² )) = 0.4
This is processed at time (2500-2200 / 2 / tan30 °) / (1000/60) = 15.6 sec. Therefore, the strain rate at this time is 0.025. ^-1 s.
[0132]
Next, the punching force has a deformation resistance of 3 kgf / mm. ² When the friction coefficient is 0.3,
3 × π / 4 × (2200 ² -1420 ² ) × ln ((2500 ² -1420 ² ) / (2200 ² -1420 ² )) × (1 + 0.1 × 0.3 / tan 30 °) + 4π / (6 · 3 · √3) = 5460640 kgf
It becomes. However, since the temperature is high at the initial stage, the punching force is half of 2730 tonf. In addition, the final thickness to prevent the bottom from coming out when
540640 / (3 / √3) / π / 1420 = 707 mm
Therefore, more is needed.
[0133]
When the product length is 4885mm, the material length is
4885 x (2200 ² -1420 ² ) / 2200 ² = 2850mm
Therefore, if the amount of upsetting at one time is 1/3 of 950 mm and the height to the mold restraining part is 700 mm of the final bottom thickness, the required upsetting force is
3 × π / 4 × 1420 ² × (1 + 0.3 × 1420/700/2) = 6196700 kgf
It becomes. With such a pressure, it can be molded by an 8000 ton press that has been used.
[0134]
On the other hand, the extrusion force in the case of backward extrusion molding is
3 × π / 4 × 2200 ² × (ln (2200 ² / (2200 ² -1420 ² )) × (1 + 2 × 0.5 / tan 45 °)) + 4π / (4 · 3 · √3) = 19186103 kgf
Therefore, a 20000 ton press is required.
[0135]
(Appendix)
In the method for manufacturing a cylinder or a container according to the next invention, when a metal billet is inserted into a molding container and the metal billet is hot expanded by a punching punch operated by a press press machine, the front side in the press direction Is a cross-sectional shape of the outer diameter with a diagonal length equal to or less than the inner diameter of the container, and the rear side is press-molded after heating a metal billet having a cross-sectional shape with an outer diameter substantially equal to the inner diameter of the container to the pressing temperature And a step of pressing while punching the center of the workpiece of the metal billet with the punching punch.
[0136]
In this method, a metal billet having a square cross section whose diagonal length is smaller than the inner diameter of the container is used on the front side in the pressing direction, so that the pressing pressure is increased by the action of bending the side surface formed by the plane on the front side in the pressing direction. It can be made smaller than before. In addition, since the rear side of the metal billet in the pressing direction suppresses the upsetting of the front side in the pressing direction, defects on the end and the container surface can be suppressed, and the pressing pressure can be reduced.
[0137]
In the method for manufacturing a cylinder or a container according to the next invention, when a metal billet is inserted into a molding container and the metal billet is hot expanded by a punching punch operated by a press press machine, the front side in the press direction Is a cross-sectional shape having an outer diameter with a diagonal length smaller than the inner diameter of the container, and a metal billet having a cross-sectional shape with a diagonal length substantially equal to the inner diameter of the container on the rear side is heated to a pressing temperature. It is characterized by comprising a step of charging into a post-press molding container and a step of pressing while punching the center of the workpiece of the metal billet with a punch.
[0138]
In this method, a metal billet having a square cross section whose diagonal length is smaller than the inner diameter of the container is used on the front side in the pressing direction, so that the pressing pressure is increased by the action of bending the side surface formed by the plane on the front side in the pressing direction. It can be made smaller than before. Further, since the metal billet used in this method has an angular cross-sectional shape on both the front side and the rear side in the pressing direction, the metal billet can be processed relatively easily as compared with the round cross-sectional shape.
[0139]
In the method for manufacturing a cylinder or a container according to the next invention, when a metal billet is inserted into a molding container and the metal billet is hot expanded by a punching punch operated by a press press machine, the front side in the press direction Is a cross-sectional shape with an outer diameter smaller than the inner diameter of the container, and the rear side is a container for press molding after heating a metal billet having a cross-sectional shape substantially equal to the inner diameter of the container to the press working temperature And a step of pressing while punching the center of the workpiece of the metal billet with a punch.
[0140]
In the container manufacturing method described above, the metal billet is expanded to the space formed between the metal billet and the inner wall of the molding container because the diagonal length of the front side in the pressing direction is smaller than the inner diameter of the container. To do. For this reason, a press pressure can be made smaller than before. In addition, since the rear side of the metal billet in the pressing direction suppresses the upsetting of the front side in the pressing direction, defects on the end and the container surface can be suppressed, and the pressing pressure can be reduced.
[0141]
In the method for manufacturing a cylinder or a container according to the next invention, when a metal billet is inserted into a molding container and the metal billet is hot expanded by a punching punch operated by a press press machine, the front side in the press direction Is a cross-sectional shape of the outer diameter with a diagonal length equal to or less than the inner diameter of the container, and the rear side is for press forming after heating a metal billet having a cross-sectional shape with an outer diameter substantially equal to the inner diameter of the container to the press working temperature A step of charging the container, a step of extending the rear side in the pressing direction of the metal billet to the inlet side end of the molding container by pushing the metal billet, and processing the metal billet with the punching punch And a step of pressing while drilling the center of the object.
[0142]
This manufacturing method of a cylinder or a container includes a step of extending the rear side of the metal billet in the pressing direction on the body portion of the container before hot expansion forming. Since this extending portion has an action of locking the metal billet to the container end during hot expansion molding, the restraint between the container and the metal billet becomes stronger, and upsetting on the front side in the press direction can be suppressed. . Further, since a metal billet having a square cross section whose diagonal length is smaller than the inner diameter of the container is used on the front side in the pressing direction, it is expanded by the action of bending each side of the square cross section. Further, the rear side of the metal billet in the pressing direction suppresses the upsetting of the front side in the pressing direction. Due to these interactions, in this manufacturing method, a thick-walled container can be formed with a smaller pressing pressure than in the backward extrusion method or the like.
[0143]
In the method for manufacturing a cylinder or a container according to the next invention, when a metal billet is inserted into a molding container and the metal billet is hot expanded by a punching punch operated by a press press machine, the front side in the press direction Is a cross-sectional shape with a diagonal length smaller than the inner diameter of the container, and the rear side is heated to a pressing temperature with a metal billet with a diagonal length approximately equal to the inner diameter of the container. A step of inserting the metal billet into the press-side container, a step of extending the rear side of the metal billet in the pressing direction to the inlet side end of the molding container, and a punch And a step of performing press working while drilling the work center of the billet.
[0144]
This manufacturing method of a cylinder or a container includes a step of extending the rear side of the metal billet in the pressing direction on the body portion of the container before hot expansion forming. Since this extending portion has an action of locking the metal billet to the container end during hot expansion molding, the restraint between the container and the metal billet becomes stronger, and upsetting on the front side in the press direction can be suppressed. . Further, since a metal billet having a square cross section whose diagonal length is smaller than the inner diameter of the container is used on the front side in the pressing direction, it is expanded by the action of bending each side of the square cross section. Further, the rear side of the metal billet in the pressing direction suppresses the upsetting of the front side in the pressing direction. Due to these interactions, in this manufacturing method, a thick-walled container can be formed with a smaller pressing pressure than in the backward extrusion method or the like. Furthermore, since the metal billet used in this method has a square cross-sectional shape on both the front side and the rear side in the pressing direction, it is relatively easy to process the metal billet as compared with a metal billet having a round cross-sectional shape.
[0145]
In the method for manufacturing a cylinder or a container according to the next invention, when a metal billet is inserted into a molding container and the metal billet is hot expanded by a punching punch operated by a press press machine, the front side in the press direction Is a cross-sectional shape with an outer diameter smaller than the inner diameter of the container, and the rear side is for press molding after heating a metal billet having an outer diameter substantially equal to the inner diameter of the container to the press working temperature A step of inserting the metal billet, a step of extending the rear side of the metal billet in the pressing direction to an end of the inlet side of the molding container by pushing the metal billet, and a center of the workpiece of the metal billet with a punch. And a step of pressing while drilling.
[0146]
This manufacturing method of a cylinder or a container includes a step of extending the rear side of the metal billet in the pressing direction on the body portion of the container before hot expansion forming. Since this extending portion has an action of locking the metal billet to the container end during hot expansion molding, the restraint between the container and the metal billet becomes stronger, and upsetting on the front side in the press direction can be suppressed. . Moreover, since the rear side of the metal billet in the pressing direction is substantially the same diameter as the inner diameter of the molding container, it is possible to suppress the upsetting of the front side in the pressing direction. Due to these interactions, in this manufacturing method, a thick-walled container can be formed with a smaller pressing pressure than in the backward extrusion method or the like. Furthermore, since the metal billet used in this method has a circular cross-sectional shape on both the front side and the rear side in the pressing direction, it is relatively easy to process as compared with metal billets having different cross-sectional shapes.
[0147]
【The invention's effect】
As described above, in the hot press molding method for a thick metal cylinder or cylindrical container according to the present invention, the front side in the pressing direction has an outer diameter smaller than the inner diameter of the container or an outer diameter of a diagonal length. A cross-sectional member or a cross-sectional member having an outer diameter with a diagonal length equivalent to the inner diameter of the container, and the rear side is a different member made of a cross-sectional shape with an outer diameter or diagonal length equivalent to the inner diameter of the container. The seamless metal billet having a radial cross-sectional shape was heated to the press processing temperature and then charged into a press molding container, and then pressed while punching the center of the workpiece of the seamless metal billet with a punch. For this reason, the seamless metal billet reduces the press molding load and improves the product yield, and a press molded product having an excellent end face shape can be obtained.
[0148]
Further, the hot press molding method for a thick metal cylinder or cylindrical container according to the present invention includes a step of extending the rear side of the metal billet in the press direction on the body of the container before the hot expansion molding. I did it. Since this extending portion has an action of locking the metal billet to the container end during hot expansion molding, the restraint between the container and the metal billet becomes stronger, and upsetting on the front side in the press direction can be suppressed. . The front side of the press was a cross-sectional member having an outer diameter smaller than the inner diameter of the container or a diagonal length, or a cross-sectional member having a diagonal length equivalent to the inner diameter of the container. For this reason, metal is supplied from the rear side of the press and processed while being expanded sideways with the effect of good plastic working of steel heated to a high temperature, so that the container space is filled and molded. Therefore, it is manufactured from a seamless metal billet into a pressed product having a predetermined shape. By these interactions, a thick container can be formed with a smaller pressing pressure than in the backward extrusion method or the like.
[0149]
Further, in the container manufacturing apparatus according to the present invention, the container body and the container bottom can be moved relative to the axial direction of the container body, and the molding container is attached to a press machine. And a perforation punch for pressurizing the metal billet inserted therein. For this reason, since the barrel part of the container and the metal billet to be molded hardly move relative to each other during the hot expansion molding, an increase in press pressure during the hot expansion molding can be suppressed.
[0150]
In the container manufacturing apparatus according to the present invention, the body of the molding container is further divided in the axial direction. For this reason, even when forming a metal billet that is long in the axial direction, the deformation of the metal billet in the axial direction during hot expansion molding can be absorbed by the entire container. Therefore, an increase in press pressure can be suppressed.
[0151]
Moreover, the metal billet for hot expansion forming according to the present invention has a polygonal cross-sectional shape perpendicular to the axial direction at least on the front side in the pressing direction. For this reason, the effect | action which bends the edge | side of a polygon, and the effect | action which suppresses upsetting of a metal billet arise. By these actions, a thick container having an axial length to diameter ratio of 1 or more can be formed with a smaller pressing pressure than in the past. Moreover, the defect which arises in the edge part and surface of a container after shaping | molding can also be suppressed.
[0152]
Further, the hot billet forming metal billet according to the present invention includes at least one flat surface on at least one of the side surface on the front side in the pressing direction or the side surface on the rear side in the pressing direction. At the time of hot expansion molding, expansion molding is performed by the action of bending the plane, so that the force required at the time of hot expansion molding is smaller than when the side surface is a curved surface. Therefore, it is possible to form a thick container that is long in the axial direction with a smaller pressing pressure than in the past. Also, internal defects such as cracks can be reduced as compared with the case where the side surface is a curved surface.
[0153]
Moreover, the metal billet for hot expansion forming according to the present invention is such that, in the metal billet for hot expansion forming, a taper that becomes narrower in the pressing direction is provided on the front side of the metal billet in the pressing direction. Further, the hot billet forming metal billet according to the present invention is such that, in the hot billing metal billet, at least one of the metal billet in the press direction front side is gradually reduced toward the press direction. The above steps were provided. These metal billets can delay the timing when the metal fills in the vicinity of the bottom of the molding container in the final stage of hot expansion molding. For this reason, upsetting is suppressed in the final stage of hot expansion molding, and as a result, the press pressure at the time of hot expansion molding can be reduced.
[0154]
In addition, since the metal billet for hot expansion forming according to the present invention has an overhanging portion at the end on the rear side in the pressing direction, the overhanging portion relates the metal billet to the container end during the hot expansion forming. Stop. By this action, the restraint between the container and the metal billet is further strengthened, and the upsetting on the front side in the pressing direction can be suppressed. In addition, since at least one plane is provided on the side surface, an effect of bending the plane and an effect of suppressing the installation of the metal billet are also produced. Therefore, the press pressure can be kept small by these interactions. Moreover, since this metal billet was previously provided with the overhang | projection part at the back side of the press direction of the metal billet at the time of manufacture, the manufacturing process of a container can be simplified.
[0155]
Moreover, in the metal billet for hot expansion forming according to the present invention, since the overhanging portion is provided on the rear side in the pressing direction, the overhanging portion locks the metal billet to the container end during the hot expansion forming. By this action, the restraint between the container and the metal billet is further strengthened, and the upsetting on the front side in the pressing direction can be suppressed. Further, since the cross-sectional shape perpendicular to the axial direction at least on the front side in the pressing direction is formed in a polygon, there is an effect of bending each side of the polygonal cross-section and suppressing the metal billet from being set up. Therefore, the press pressure can be kept small by these interactions. In addition, since this metal billet is provided with an overhang portion on the rear side in the pressing direction of the metal billet at the time of manufacture, the process of forming the overhang portion on the rear side in the press direction becomes unnecessary, and the manufacturing process of the container is simplified. Can be.
[0156]
Moreover, in the metal billet for hot expansion forming of this invention, since the overhang | projection part was provided in the back side of the press direction, this overhang part latches a metal billet to a container edge part at the time of hot expansion molding. By this action, the restraint between the container and the metal billet is further strengthened, and the upsetting on the front side in the pressing direction can be suppressed. In addition, since the cross-sectional shape perpendicular to the axial direction at least on the front side in the pressing direction is formed into a polygon, the above-described bending action and the action of suppressing metal flow also occur. Furthermore, since the front side of the press is made to become thinner stepwise in the pressing direction, the upsetting phenomenon can be suppressed in the final stage of the hot expansion molding, and the increase in press pressure can be suppressed. Therefore, the press pressure can be kept small by these interactions. In addition, since the metal billet is provided with the overhang portion on the rear side in the press direction of the metal billet at the time of manufacture, the step of forming the overhang portion on the rear side in the press direction is not necessary.
[0157]
Moreover, in the metal billet for hot expansion forming of this invention, since the overhang | projection part was provided in the back side of the press direction, this overhang part latches a metal billet to a container edge part at the time of hot expansion molding. By this action, the restraint between the container and the metal billet is further strengthened, and the upsetting on the front side in the pressing direction can be suppressed. In addition, since at least one plane is provided on at least one of the side surfaces of the metal billet, the bending action and the action of suppressing the metal flow also occur. Further, since the front side of the press is gradually reduced toward the press direction, the upsetting phenomenon can be suppressed in the final stage of the hot expansion molding, and the increase in press pressure can be suppressed. Therefore, the press pressure can be kept small by these interactions. In addition, since the metal billet is provided with the overhanging portion on the rear side in the pressing direction of the metal billet at the time of manufacture, the step of forming the overhanging portion on the rear side in the pressing direction becomes unnecessary.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing an example of a bottomed container according to Embodiment 1. FIG.
2 is an explanatory view showing a manufacturing process of the bottomed container shown in FIG. 1. FIG.
FIG. 3 is a perspective view showing an example of a metal billet used in the first embodiment.
FIG. 4 is an explanatory view showing another billet according to the first embodiment.
FIG. 5 is a conceptual diagram showing a state of deformation of a metal billet.
FIG. 6 is a perspective view showing another metal billet applicable to the first embodiment.
FIG. 7 is an explanatory view showing another metal billet applicable to the first embodiment.
FIG. 8 is a cross-sectional view showing a division part of the trunk part of the container used in the first embodiment.
FIG. 9 is a schematic view showing an apparatus for cutting the outside of a hot-expanded bottomed container.
FIG. 10 is a schematic view showing an apparatus for processing the inside of a bottomed container.
FIG. 11 is an explanatory diagram showing an example of a processing method for the inside of the bottomed container.
12A and 12B show a cask according to an embodiment of the present invention, wherein FIG. 12A is an axial sectional view, and FIG. 12B is a radial sectional view.
13 is a perspective view showing a bottomed container according to Embodiment 2. FIG.
14 is a cross-sectional view showing a container body and a punch for manufacturing a bottomed container according to Embodiment 2. FIG.
15 is a cross-sectional view perpendicular to the axial direction showing an example of a bottomed container that can be formed by the manufacturing method according to Embodiment 2. FIG.
16 is a cross-sectional view showing a container body and a punch for manufacturing a bottomed container according to Embodiment 2. FIG.
FIG. 17 is an axial cross-sectional view showing a bottomed container according to Embodiment 3.
FIG. 18 is an explanatory view showing a method of providing a counterbore part in a bottomed container.
FIG. 19 is an axial sectional view showing an example of a bottomed container that can be molded by the manufacturing method according to the present invention.
20 is an axial sectional view showing a bottomed container according to Embodiment 4. FIG.
21 is an explanatory view showing a manufacturing process of the bottomed container shown in FIG. 12. FIG.
22 is an explanatory view showing a manufacturing process of the cask bottomed container shown in FIG. 12. FIG.
FIG. 23 is an explanatory view showing a manufacturing process of the cask bottomed container shown in FIG. 12;
24 is an explanatory diagram showing a manufacturing process of the cask bottomed container shown in FIG. 12. FIG.
25 is an explanatory view showing a manufacturing process of the cask bottomed container shown in FIG. 12. FIG.
FIG. 26 is an explanatory view showing a manufacturing process of the cask bottomed container shown in FIG. 12;
FIG. 27 is an explanatory view showing another manufacturing method of the bottomed container.
FIG. 28 is an explanatory diagram showing an embodiment of a different manufacturing method.
FIG. 29 is a cross-sectional view showing an example of a conventional cask.
30 is an explanatory view showing an example of a method for producing the cask bottomed container shown in FIG. 29. FIG.
FIG. 31 is an explanatory view showing a method for producing a bottomed container by the Erhardt perforation method.
[Explanation of symbols]
100 cask
1 Bottomed container
1a trunk
1b Bottom
2 Resin
3 baskets
4 outer cylinder
5 Primary lid
6 Secondary lid
7, 8 Resin
9 Shield
10 Internal fin
20 Slide table
21-23 Dice
21a Opening part
24-26 Pressure table
28 stem
29 Hanging jig
30-32 spacer
W, 200 metal billet
201 Overhang part
202 rim
203 protrusion
300, 300a, 300b Container body
301 Bottom of container
302 Cylindrical spacer
303 annular metal plate
304 cylinder
305 metal plate
310 Positioning guide
350 spaces
400 large punch
27, 410, 411 Perforated punch
800 spot face
900, 910, 920 Projection images of cross sections perpendicular to the axial direction
950, 960, 970 Cross section perpendicular to the axial direction

Claims (4)

  The front side in the pressing direction is a cross-sectional member having an outer diameter smaller than the inner diameter of the molding container or a diagonal length, or a cross-sectional member having a diagonal length equivalent to the inner diameter of the molding container. In addition, the rear side is a container for press molding after heating a seamless metal billet having a cross-sectional shape with a cross-sectional shape having an outer diameter or a diagonal length equal to the inner diameter of the molding container to a pressing temperature. The metal billet is pushed in and the rear side in the pressing direction of the metal billet is extended to the inlet end of the molding container, and the molding is performed on the rear side in the pressing direction of the seamless metal billet. Forming an overhanging portion that engages with the inlet end of the body portion of the container for the container, and then pressing while punching the workpiece center of the seamless metal billet with a punch. Excellent Thick metal cylindrical object or hot press molding of the cylindrical container shape.   The front side in the pressing direction is a cross-sectional member having an outer diameter smaller than the inner diameter of the molding container or a diagonal length, or a cross-sectional member having a diagonal length equivalent to the inner diameter of the molding container. The rear side is a member having a cross-sectional shape having an outer diameter or a diagonal length equivalent to the inner diameter of the molding container, and further includes an overhanging portion that engages with the inlet end of the trunk portion of the molding container. The seamless metal billet with a different cross-sectional shape is heated to the press processing temperature, then inserted into a press molding container, and then pressed while punching the workpiece center of the seamless metal billet with a punch. A hot press forming method of a thick metal cylinder or cylindrical container having an excellent end face shape.   The front side in the pressing direction is a cross-sectional member having an outer diameter smaller than the inner diameter of the molding container or a diagonal length, or a cross-sectional member having a diagonal length equivalent to the inner diameter of the molding container. In addition, the rear side is a container for press molding after heating a seamless metal billet having a cross-sectional shape with a cross-sectional shape having an outer diameter or a diagonal length equivalent to the inner diameter of the molding container to a pressing temperature. The metal billet is pushed in to extend the rear side in the press direction of the metal billet to the inlet side end of the molding container, and the rear side in the press direction of the seamless metal billet is Forming an overhang that engages the inlet end of the barrel of the molding container and then drilling the center of the workpiece of the seamless metal billet with a punch, When a frictional force is generated between the billet and the inner wall of the molding container, pressing the barrel of the molding container together with the seamless metal billet while moving it in the direction opposite to the pushing direction of the punch. A hot press molding method for a thick metal cylinder or cylindrical container having an excellent end face shape.   The front side in the pressing direction is a cross-sectional member having an outer diameter smaller than the inner diameter of the molding container or a diagonal length, or a cross-sectional member having a diagonal length equivalent to the inner diameter of the molding container. The rear side is a member having a cross-sectional shape having an outer diameter or a diagonal length equivalent to the inner diameter of the molding container, and further includes an overhanging portion that engages with the inlet end of the trunk portion of the molding container. A seamless metal billet having a different diameter cross-sectional shape is heated to a press processing temperature and then charged into a press molding container. After that, while punching the workpiece center of the seamless metal billet with a punch, When a frictional force is generated between the seamless metal billet and the inner wall of the molding container, the barrel of the molding container is opposite to the pushing direction of the punch together with the seamless metal billet. Hot press-forming method, thick metal cylindrical object or cylindrical container having excellent end surface shape, characterized in that the pressing while moving the can.

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