JP3713176B2

JP3713176B2 - Pressure coagulation casting method and apparatus

Info

Publication number: JP3713176B2
Application number: JP2000000476A
Authority: JP
Inventors: 清藤野
Original assignee: 有限会社藤野技術コンサルタント
Priority date: 2000-01-05
Filing date: 2000-01-05
Publication date: 2005-11-02
Anticipated expiration: 2020-01-05
Also published as: JP2001191170A

Description

【０００１】
【発明の属する技術分野】
本発明は、凝固時にひけ巣の発生がなくかつガスの巻込みのないアルミニウム合金等の鋳造品を鋳造することができる、金型キャビテイ内へ溶湯を下から充填、特に真空吸引充填する堅型鋳造装置やそれを用いた堅型鋳造方法に関する。
【０００２】
【従来の技術】
軽合金製品等の鋳造品、特に強度が必要とされる部品等を鋳造する場合、溶湯鋳込時におけるガスの巻込みを防止するため、堅型ダイカストマシンが一般的に使用されている。例えば、自動車用アルミホイール等を製造する方法については、特公平３−４２９７号公報に記載されているように、金型キャビテイ内へ溶湯を導入するためのスリーブ径より小さい径の溶湯流入ゲート、該ゲート内径よりわずかに小さい径の加圧ピンを用いた鋳造方法は既に知られているが、溶湯凝固時に発生するひけ巣を充分に防止することができない上に、酸化物の混入、ガスの巻込みに対しても必ずしも充分に防止しうるものではなかった。
【０００３】
本発明者は、一般的な部品を鋳造する場合の酸化物の混入やガスの巻き込みを防止する竪型鋳込み方法として、下側の固定金型と上側の可動金型と固定金型の下側において射出装置を設け、固定金型に鋳込スリーブの内径よりも小径の縦方向の円形ゲートを設け、円形ゲートへの挿入部の直径が円形ゲート内径よりもわずかに小さい径のピンを可動金型に摺動自在に設けてピンを円形ゲート内を昇降させ得るように設け、可動金型の円形ゲート上部に設けた円形の溜部の入口の直径を鋳込時に円形ゲートから噴出する溶湯噴流の直径よりも大きく、溜部の天井高さを前記溶湯噴流の到達高さよりも高くした堅型鋳込装置を用いて、溶湯を金型のキャビテイ内へ鋳込み、溶湯がキャビテイ内を充填したらピンを突出させて押湯作用を行わせる方法を提案した（特開平１０−１４６６６３号公報）。この方法は、酸化物の混入やガスの巻き込みあるいは溶湯凝固時に発生するひけ巣をある程度防止しうる点では優れているといえるものの、ガスの巻き込みや溶湯凝固時に発生するひけ巣を充分に防止する点で全く問題がないとはいえなかった。
【０００４】
また、上記特公平３−４２９７号公報や特開平１０−１４６６６３号公報に記載の鋳込み方法は、いずれも高圧鋳込みのために大きい射出力及び型締力を必要とし、コストの高い設備が必要とされていた。他方、低設備コストの鋳込み方法としては低圧鋳造方法や真空吸引鋳造方法（特開昭５８−５５１６６号公報、特開平５−２１２５２８号公報、特開平６−１８２５２０号公報、特開平７−３２１２５号公報、特開平９−５７４２２号公報）が知られているが、酸化物の混入やガスの巻き込みあるいは凝固時に発生するひけ巣を充分に防止することができず、強度を必要とする鋳造品には適用されていなかった。また、例えば上記特開昭５８−５５１６６号公報には、湯槽上部空間を減圧にすると共に、エアベントバルブを介してキャビテイ内を減圧し、その後湯槽上部空間を加圧状態として溶湯をキャビテイ内に鋳込むという複雑な切替弁やバルブを用いる方法や、湯槽上部空間を減圧にすることにより、キャビテイ内のガスをストーク及び湯槽内を通して排気した後、湯槽上部空間を加圧状態として溶湯をキャビテイ内に鋳込むという複雑な切替弁やバルブを用いる上に溶湯にガスが混入する方法が開示されているように、キャビテイ内のガスを抜くために色々な方法が考案されているが、従来の鋳込み装置では稼動上のトラブルも多く、現在まで実用面において必ずしも満足できるものは存在しなかった。
【０００５】
【発明が解決しようとする課題】
堅型ダイカストマシンによる鋳造において、製品不良の原因となるスリーブに注湯された溶湯の表面にある酸化物、スリーブ内面で冷却されて発生するチル層すなわち凝固層の製品への混入を防止し、ゲート部におけるガスの巻込みを防止するとともに、凝固収縮によって発生するひけ巣を防止するためには、キャビテイ内のガスをほぼ完全に排出すると同時に、充分量の溶湯を有効に加圧して補充する必要がある。またその際、稼動運転中のトラブルを少なくするために実用上キャビテイの構造や鋳造装置全体の構造を簡単にする必要もある。本発明の課題は、キャビテイ内のガスをほぼ完全に排出すると同時に、閉塞されたキャビテイ内の溶湯を有効に加圧することができ、ひけ巣の発生がなくかつガスの巻込みのない鋳造品を鋳造するための、低コストでかつ構造が簡単な竪型鋳造装置及び該竪型鋳造装置を用いる竪型鋳造方法を提供することにある。
【０００６】
【課題を解決するための手段】
本発明者は上記課題を解決するために鋭意研究し、キャビテイ内のガスを排出することにより溶湯を鋳込み、ガス排出通路からガスを排出すると同時にガス排出通路に連設されている溶湯凝固ゾーン用空隙の先湯を凝固させるという簡単な手段で溶湯をキャビテイ内に閉じこめ、かかる閉塞状態の溶湯を複数箇所で圧力伝達距離を短くして有効に加圧すると、ひけ巣の発生がなくかつ酸化膜の混入及びガスの巻込みのない鋳造品を鋳造することができることを見い出し、本発明を完成するに至った。
【０００７】
すなわち本発明は、ガス排出通路及び該ガス排出通路の近傍に設けられたガス排出通路に連通した溶湯凝固ゾーン用空隙を備えた金型キャビテイを形成することができる下側の固定金型及び上側の可動金型と、前記金型キャビテイ内へ溶湯を下方から供給充填する鋳込手段と、該鋳込手段により金型キャビテイ内に鋳込まれた溶湯がキャビテイ内を充填した後、固定金型に設けられている溶湯流入ゲートを塞ぐ閉塞手段と、閉塞された金型キャビテイ内の溶湯を加圧する加圧手段とを備えた竪型鋳造装置であって、前記金型キャビテイが、キャビテイ製品部とキャビテイ湯溜部とを備え、該キャビテイ湯溜部が溶湯流入ゲートの上方に位置するキャビテイ第１湯溜部と、前記キャビテイ製品部のキャビテイ第１湯溜部と反対側の端部近傍上方に位置する１又は２以上のキャビテイ第２湯溜部とからなることを特徴とする竪型鋳造装置（請求項１）や、ガス排出通路及び該ガス排出通路の近傍に設けられたガス排出通路に連通した溶湯凝固ゾーン用空隙を備えた金型キャビテイを形成することができる下側の固定金型及び上側の可動金型と、前記金型キャビテイ内へ溶湯を下方から供給充填する鋳込手段と、該鋳込手段により金型キャビテイ内に鋳込まれた溶湯がキャビテイ内を充填した後、固定金型に設けられている溶湯流入ゲートを塞ぐ閉塞手段と、閉塞された金型キャビテイ内の溶湯を加圧する加圧手段とを備えた竪型鋳造装置であって、前記固定金型に設けられている溶湯流入ゲートを塞ぐ閉塞手段が、円形溶湯流入ゲートを開閉することができる閉塞ピンを備え、該閉塞ピンの円形溶湯流入ゲートへの挿入部の直径が円形溶湯流入ゲート内径よりもわずかに小さく構成されており、また前記円形溶湯流入ゲート内径が固定金型の下側に配設された鋳込用ストークの内径よりも小さくなるように構成されていることを特徴とする竪型鋳造装置（請求項２）や、閉塞された金型キャビテイ内の溶湯を加圧する加圧手段が、 ( １ ) キャビテイ第１湯溜部の上方の可動金型に摺動自在に配設され、その中心に閉塞ピンを摺動自在に設けている加圧ステム、及び／又は ( ２ ) キャビテイ第２湯溜部の上方の可動金型に摺動自在に配設された、１若しくは２以上の加圧ピンを備えていることを特徴とする請求項１記載の竪型鋳造装置（請求項３）や、加圧ステム及び閉塞ピンが円形溶湯流入ゲート上部の可動金型に配設され、これらを上昇させた状態で形成される円形のキャビテイ第１湯溜部の入口の直径を円形溶湯流入ゲートの直径の１．４倍よりも大きくし、加圧ステム及び閉塞ピンの上昇限におけるキャビテイ第１湯溜部の天井の高さを円形溶湯流入ゲートから噴出する溶湯噴流の高さよりも１０ｍｍ以上高くなるように構成したことを特徴とする請求項３記載の竪型鋳造装置（請求項４）や、金型キャビテイ内へ溶湯を下方から充填する鋳込手段が、金型キャビテイ内のガスを真空吸引することによって、固定金型の下側に設けられた鋳込用ストークを通じて、下方の溶湯保持炉から溶湯を真空吸引充填する真空吸引機構を備えていることを特徴とする請求項１〜４のいずれか記載の竪型鋳造装置（請求項５）や、ガス排出通路に連通した溶湯凝固ゾーン用空隙が、加圧手段に近接して設けられていることを特徴とする請求項１〜５のいずれか記載の竪型鋳造装置（請求項６）や、加圧手段に近接して設けられているガス排出通路に連通した溶湯凝固ゾーン用空隙が、加圧ステム及び／又は加圧ピンの外周面と可動金型内周面との間に形成されるガス排出空隙又はガス排出溝を介してガス排出孔に連通していることを特徴とする請求項６記載の竪型鋳造装置（請求項７）や、加圧ステム及び／又は加圧ピンと同芯に設けられ、加圧ステム及び／又は加圧ピンの直径よりも１〜５ mm 大きい内径で１０〜４０ mm 程度の深さを有する溶湯凝固ゾーン用空隙と、ガス排出空隙が加圧ステム及び／若しくは加圧ピンと同芯に設けられ、加圧ステム及び／若しくは加圧ピンの直径より０．４〜１．０ mm 大きい内径のガス排出空隙、又は加圧ステム及び／若しくは加圧ピンの外周面に軸線状に伸びたガス排出溝とを備えたことを特徴とする請求項７記載の竪型鋳造装置（請求項８）に関する。
【０００８】
また本発明は、請求項１〜８のいずれか記載の竪型鋳造装置を用いて、溶湯保持炉からストークを通じて溶湯を金型のキャビテイ内へ鋳込み、溶湯がキャビテイ内を充填した後、固定金型に設けられている溶湯流入ゲートを塞ぎ、その後金型キャビテイ内の溶湯を加圧して、凝固時にひけ巣の発生がなくかつガスの巻込みのない鋳造品を鋳造することを特徴とする堅型鋳造方法（請求項１０）に関する。なお、好ましい堅型鋳造方法としては、上記本発明の竪型鋳造装置を用いて、加圧ピンの後退位置で、金型キャビテイ内への溶湯の充填を開始し、先湯の流速をキャビテイ第２湯溜部で減速させ、ガス排出空隙又はガス排出溝を介して金型キャビテイ内のガスを排出させながら、溶湯凝固ゾーン用空隙の溶湯を冷却凝固させ、金型キャビテイ内に溶湯が充填密封された後、加圧ピンを前進させてキャビテイ第２湯溜部の溶湯を加圧する方法や、複数の溶湯凝固ゾーンに隣接するガス排出空隙又はガス排出溝から真空ガス抜きを行うことによってガスの巻き込みをより減少せしめると共に、加圧ステム及び複数の加圧ピンから溶湯を加圧することによって圧力伝達距離を短くする方法や、鋳造品が軽金属合金の鋳造品である方法を例示することができる。
【０００９】
【発明の実施の形態】
本発明の竪型鋳造装置は、ガス排出通路を備えた金型キャビテイを形成することができる下側の固定金型及び上側の可動金型と、該金型キャビテイ内へ溶湯を下方から供給充填することができる鋳込手段と、該鋳込手段により金型キャビテイ内に鋳込まれた溶湯がキャビテイ内を充填した後、固定金型に設けられている溶湯流入ゲートを塞ぐことができる閉塞手段と、閉塞された金型キャビテイ内の溶湯を加圧することができる加圧手段とを備え、前記ガス排出通路に連通した溶湯凝固ゾーン用空隙を該ガス排出通路の近傍に設けることを特徴とし、本発明の竪型鋳造装置を用いると、凝固時にひけ巣の発生がなくかつガスの巻込みのない鋳造品を鋳造することができる。そして、かかる鋳造品としては特に限定されるものではないが、軽金属合金、特に凝固収縮が大きいアルミニウム合金が好ましい。アルミニウムは凝固するとき約７％収縮することから、ひけ巣の発生を防止しうる本発明の鋳造装置や鋳造方法は、アルミニウム合金等の凝固収縮が大きい軽金属合金からなる溶湯から鋳造する場合に、特に有利に適用することができる。
【００１０】
上記金型キャビテイとしては、下方から溶湯を充填供給することができ、少なくとも金型キャビテイ内への溶湯充填時にキャビテイ内に存在するガスを排出することができるガス排出通路と、該ガス排出通路に連通した溶湯凝固ゾーン用空隙を有するものであれば特に制限されるものではないが、キャビテイ製品部とキャビテイ湯溜部を備え、該キャビテイ湯溜部が溶湯流入ゲートの上方に位置するキャビテイ第１湯溜部と、前記キャビテイ製品部のキャビテイ第１湯溜部と反対側の端部近傍上方に位置する１又は２以上のキャビテイ第２湯溜部とからなるものが好ましい。そして、キャビテイ製品部とキャビテイ第１湯溜部とはサイドゲートを介して連通しており、キャビテイ第１湯溜部はキャビテイ第２湯溜部に比べて、通常より大きい容積を有している。また、ガス排出通路としては、可動金型中を貫通しているガス排出孔と、ガス排出空隙又はガス排出溝とから構成されるものを例示することができる。
【００１１】
本発明の竪型鋳造装置における、前記金型キャビテイ内へ下方から溶融アルミニウム等の溶湯を供給充填する鋳込手段としては、従来公知の鋳込手段を用いることができ、例えば、上記特公平３−４２９７号公報や特開平１０−１４６６６３号公報に記載されているような高圧又は低圧鋳込み用のプランジャーを備えた射出手段や、上記特開昭５８−５５１６６号公報に記載されているような密封構造の湯槽内の溶湯表面にガス圧を作用させる加圧機構を備えた低圧鋳込手段等を挙げることもできるが、溶湯充填時のガスの巻き込み防止や、低設備コストでかつ簡単な構造で構成することができる真空吸引機構、すなわち、金型キャビテイ内のガスを真空吸引することによって、下側固定金型の下方に隣接して設けられた鋳込用ストークを通じて、下方の溶湯保持炉から溶湯を真空吸引充填する真空吸引機構を備えている鋳込手段が好ましい。この場合、注入される溶湯の先端は注入開始まで溶湯保持炉の溶湯の湯面と同じ高さにあり、真空によって鋳込みを開始してもストークの長さは短く、かつ加熱してあるので凝固層の発生は少なく、凝固層混入による不良の発生がない。また、真空吸引による給湯の充填は、湯面加圧による低圧鋳造のように溶湯保持炉を密閉シールする必要が無く、溶湯保持炉の形状を自由なものとすることができ、ストークの周辺だけ幅の狭い形状にすることにより溶湯の湯面を金型に近づけ、給湯を容易にすることができる。
【００１２】
また、下側固定金型には、下方からキャビテイ内へ溶湯を充填供給するための上記鋳込用ストーク又はスリーブとキャビテイ第１湯溜部との連通部が形成され、該連通部には溶湯流入ゲートが設けられている。かかる溶湯流入ゲートの形状としては特に制限されないが、加工の容易さ等からして通常断面が円形の形状が好ましく、この場合、円形溶湯流入ゲートの内径は鋳込用ストークの内径よりも小さくなるように構成しておくことが好ましい。このように構成しておくことにより、下方から充填供給されてくる溶湯をキャビテイ第１湯溜部内へ噴出させることができ、後述するように、鋳造製品不良の一因となる鋳込用ストークに注湯された溶湯の表面にある酸化膜やストーク内面で冷却され発生するチル層（凝固層）の製品への混入を防止することができる。
【００１３】
前記鋳込手段により金型キャビテイ内に鋳込まれた溶湯がキャビテイ内を充填した後、固定金型に設けられている上記溶湯流入ゲートを塞ぐ本発明における閉塞手段としては、溶湯流入ゲートを閉塞しうる機構を備えているものであればどのようなものでもよく、例えば円形溶湯流入ゲートを開閉することができる該ゲート上方に配設される閉塞ピンを具体的に挙げることができ、この場合、該閉塞ピンの円形溶湯流入ゲートへの挿入部の直径を円形溶湯流入ゲート内径よりもわずかに小さくしておくことが閉塞密封性の点で好ましい。この閉塞ピンは可動金型に対して液密的に摺動自在に進退出することができるように保持することが好ましく、また、後述するように、加圧ステムが可動金型に対して液密的に摺動自在に保持される場合は、該加圧ステムの中心に同軸かつ液密的に摺動自在に閉塞ピンを設けることもできる。
【００１４】
上記のように、加圧ステム及び閉塞ピンが円形溶湯流入ゲート上部の可動金型に配設される場合、これらを退出（上昇）させた状態で形成される円形のキャビテイ第１湯溜部の入口の直径を円形溶湯流入ゲートの直径の１．４倍よりも大きくし、加圧ステム及び閉塞ピンの退出上限時における湯溜部の天井の高さを、前述した円形溶湯流入ゲートから噴出する溶湯噴流の高さよりも１０ｍｍ以上高くなるように、キャビテイ第１湯溜部を構成することが好ましい。このように湯溜部の入口の直径を円形ゲート直径の１．４倍以上とした場合、溶湯噴流の高さｈは、円形ゲートにおける溶湯の通過速度をｖ、重力の加速度をｇとしたとき、ｈ＝ｖ²／２ｇの計算式により求めることができるので、キャビテイ第１湯溜部の天井高さを湯溜部の入口直径の約１．５倍以上にすれば、一般的な範囲で鋳込速度を早くしても、キャビテイ第１湯溜部の天井は円形溶湯流入ゲートから噴出する溶湯噴流の高さよりも１０ｍｍ以上高くなることになり、溶湯噴流が天井面に衝突することがなく、衝突によるガスの巻き込みも防止することができる。
【００１５】
例えば、溶湯の給湯・充填速度は製品の形状によっても異なるが、一般的に円形ゲート内の通過速度は１．０〜２．０ｍ／ｓｅｃが好ましく、その場合円形ゲートからの噴流高さは通常５０〜２００ｍｍ位になるが、キャビテイ第１湯溜部の天井の高さが溶湯噴流の高さよりも１０ｍｍ以上高くなっている場合、自由表面が形成され湯面に残っていた酸化物も表面に残り、そして上記湯溜部の上部に残っているガスも封じ込められたままで下降流とはならず、更にガスは加圧ステムの外周の空隙から真空で排出されるので溶湯にガスを巻き込むこともない。他方、噴流速度が余り遅いと天井に衝突することもなく、ガスの巻き込みは減少するが、鋳込み時間が長くなり、溶湯がキャビテイ製品部内を流れる速度が遅くなり、その間に冷却凝固が進み、流速が一層低下してキャビテイ製品部内への溶湯充填が不充分となり、加圧しても圧力伝達が悪くひけ巣の発生の可能性が大きくなる。したがって、鋳込み速度はできるだけ速くする方が好ましく、このためにもキャビテイ第１湯溜部の天井高さは高くする方が好ましい。そして、キャビテイ第１湯溜部の天井を高くしてその体積を大きくしておくと、真空吸引力が弱くなり、キャビテイ製品部内の狭い所への溶湯の充填が不充分な場合が生じる可能性があっても、加圧ステム等の充分な加圧により補充充填することができるので問題はない。
【００１６】
以上のようにキャビテイ内にキャビテイ第１湯溜部を形成することにより、高圧又は低圧鋳込みを採用した場合であっても、閉塞ピンや加圧ステムを進出（下降）させる場合に、湯溜部の最上部に存在する酸化物やガス巻込み層は押し出されることなくキャビテイ第１湯溜部に滞留し、キャビテイ製品部に混入することがない。また特に、真空吸引鋳込みを採用する場合、前記のように、給湯用のストークは溶湯保持炉の湯面の下に入っており、湯面で発生した酸化膜は湯面に浮いていることから、ストークに入ることはないものの、ストーク内の湯面は金型を通じて入ってくる空気によってわずかに酸化する恐れがあるが、この少量の酸化膜は噴流の先端にあってキャビテイ第１湯溜部の中に全部飛び込み、サイドゲートを介してキャビテイ製品部の方に流出することはなく、鋳造製品に酸化物が混入することはなくなり、このため鋳造製品の不良、強度のばらつきもなくなることになる。
【００１７】
次に、閉塞された金型キャビテイ内に充填されている溶湯を加圧することにより、凝固時にひけ巣の発生しない、しかも噴流によりガスを巻き込みのない鋳造品を鋳造することができる。閉塞された金型キャビテイ内の溶湯を加圧するための加圧手段としては、キャビテイ第１湯溜部の上方の可動金型に摺動自在に設けられ、その中心に閉塞ピンを摺動自在に設けている前記加圧ステムや、キャビテイ第１湯溜部とはキャビテイ製品部を介して離れた位置にある前記キャビテイ第２湯溜部の上方の可動金型に摺動自在に配設された加圧ピンを具体的に例示することができる。加圧ピンは複数設けることが好ましく、またその直径は、キャビテイ第２湯溜部の深さの２／３〜１倍が好ましい。さらに、これら加圧ステムと加圧ピンは併用することが好ましい。このように、離れた位置にある加圧ステムと複数の加圧ピンとから溶湯を加圧することによって、キャビテイ内の溶湯への圧力伝達距離を短くすることにより、キャビテイ製品部に均一に圧力を伝えることができ、小さな加圧圧力で凝固時にひけ巣の発生しない鋳造品を鋳造することができる。その結果、小さな型締力の鋳造装置で緻密な組織の鋳造品を鋳造することが可能となる。また、加圧ステム及び加圧ピンを製品の形態に応じて適当な位置に配置することによって、キャビテイ製品部の溶湯の圧力伝達距離をさらに短くし、圧力伝達をより均一かつ充分なものとすると、より小さな加圧圧力でひけ巣の発生を防止することができる。
【００１８】
従来の鋳造装置においては、一般に、凝固時にひけ巣の発生しない鋳造品を鋳造するため、加圧手段による溶湯の加圧速度を大きくし、かつ急速に加圧することが行われているが、この場合、圧力伝達が良すぎて型開き力が大きくなりバリを吹き、型締め力も大きくする必要がある。しかし、反対に加圧速度を遅くすると、溶湯の凝固収縮に追いつかずひけ巣が発生することになる。他方、本発明によると、小さな加圧圧力で凝固時にひけ巣の発生しない鋳造品を鋳造することができるので、型開き力を検出して加圧速度を所定の速度に調節して、バリ吹きを防止しうる小さい型締め力でも均一かつ充分な圧力伝達を行うことができる。このように本発明においては、加圧時の加圧ステムや加圧ピンの進出速度をキャビテイ製品部内の溶湯の凝固収縮速度に適応した速度となるようにプログラム制御を行う等、加圧速度を調節することにより、小さい型締め力のプレス装置でバリ吹きを防止しながらひけ巣の発生を防止することができ、例えば、パスカルの原理が働かない凝固収縮中の溶湯に対する加圧力及び加圧速度を、バリの吹かない範囲で凝固速度に応じて制御することによって、従来の高圧法に比較して１／３〜１／５の小さい型締力の装置で、酸化物、凝固層の混入やガスの巻き込みのない緻密な組織の鋳造品を得ることができる。
【００１９】
また、スクイズ鋳造等の竪型ダイカスト法の場合、アキュラッドピン（センターピン）による加圧を早くすると鋳込みプランジャーを押し下げることになるので、少し時間を遅らせて、すなわちゲート部の凝固が進み、鋳込みプランジャーへの圧力伝達が小さくなってから加圧するので、キャビテイ内の溶湯の凝固も進行し、溶湯補充には大きい圧力を必要とし、場合によってはそのタイミングが合わず、ひけ巣が発生することがある。これに対して、本発明においては溶湯流入ゲートの閉塞手段を備えているので、まだ凝固の進行の少ない段階から加圧して溶湯を補充充填することができ、また、加圧ステムと所定の位置に配設した複数の加圧ピンによって加圧するので圧力伝達距離も短く、小さい圧力で均一かつ充分な補充充填を行うことができる。このように加圧圧力を低圧とすることができる結果、金型の型締め力も小さくて済み、型締め装置や金型のコストを低廉に抑えることができる。またこの鋳込み速度及び加圧開始速度がスクイズ鋳造よりも早いので、生産サイクルタイムは短くなり、生産性も向上する。
【００２０】
本発明は、ガス排出通路に連通した溶湯凝固ゾーン用空隙を該ガス排出通路の近傍に設けること、特に加圧手段に近接してガス排出通路に連通した溶湯凝固ゾーン用空隙を設けることを大きな特徴とする。かかる溶湯凝固ゾーン用空隙としては、例えば真空吸引等によりキャビテイ内のガスをガス排出通路から排出した後に、溶湯凝固ゾーンとなる空隙で先湯を凝固させることができ、前記閉塞手段と相俟って、簡単にキャビテイ内を密封・閉塞することができる空隙であればどのようなものでもよく、かかる溶湯凝固ゾーン用空隙を単に設けておくだけで、前記エアベントバルブやフィルター等を配設しかつ複雑な切替弁やバルブを用いることなく、簡単にキャビテイ内を密封・閉塞することができ、また鋳造装置の稼動に際して圧力調節等の複雑な操作も不要となり、さらに故障等の発生がないことから、本発明の鋳造装置は極めて実用的であるといえる。
【００２１】
また、上記加圧手段に近接して設けられるガス排出通路に連通した溶湯凝固ゾーン用空隙としては、前記加圧ステム及び／又は加圧ピンの外周面と可動金型内周面との間に形成されるガス排出空隙又はガス排出溝を介してガス排出孔に連通している溶湯凝固ゾーン用空隙を例示することができ、かかる溶湯凝固ゾーン用空隙としては、加圧ステム及び／又は加圧ピンと同芯に設けられ、加圧ステム及び／又は加圧ピンの直径よりも１〜５mm大きい内径で１０〜４０mm程度の深さ（長さ）を有する溶湯凝固ゾーンとなる空隙を具体的に例示することができる。このように、それぞれの湯溜部の外径を加圧ステム及び加圧ピンの外径よりもわずかに大きくしておくことにより、各湯溜部の外周壁に生じた凝固層が製品の中に入ることを防止することができるとともに、加圧ステム及び加圧ピンの加圧抵抗を少なくすることができる。そして、上記のように、溶湯凝固ゾーン用空隙を溶湯の温度や鋳込速度に適合した寸法に設計製作しておくと、溶湯が充填された時に先湯がこの空隙部分で冷却凝固してガス排出空隙やガス排出溝に浸入することはない。かかる溶湯凝固ゾーン用空隙は、真空鋳込法ばかりでなく、通常の低圧鋳込法やダイカスト法による鋳造装置にも設けることができる。
【００２２】
溶湯凝固ゾーン用空隙と隣接する上記ガス排出空隙やガス排出溝としては、先湯が流入しない大きさや先湯が流入しない構造のものが好ましく、例えば、ガス排出空隙としては、加圧ステム及び／又は加圧ピンと同芯に設けられ、加圧ステム及び／又は加圧ピンの直径より０．４〜１．０mm程度大きい内径のガス排出空隙を具体的に挙げることができ、上記ガス排出溝としては加圧ステム及び／又は加圧ピンの外周面に軸線状に伸びたガス排出溝を具体的に挙げることができる。そして、金型キャビテイを真空にする際、空気の侵入を防止するために、パーテイング面にはガス排出孔、及びガス排出空隙若しくはガス排出溝等からなるガス排出通路を設けずにシールパッキングを設置し、ガスの残存しやすいキャビテイの高い位置、例えば湯溜部の上方にガス排出通路を設置することが好ましい。また、加圧ステムや加圧各ピンの摺動部等には凡てシールパッキングを設置し金型外部からの空気の漏入を防止することが好ましい。
【００２３】
ところで、キャビテイ内の真空度を水柱２０００〜４０００ｍｍ程度に設定することにより、前記のように溶湯の充填速度を１．０〜２．０ｍ／秒とすることができ、かかる真空度の場合、加圧ステムや加圧ピンの外周に近接して設けられた溶湯凝固ゾーン用空隙やガス排出空隙等の２段空隙部における空気抵抗が大きくなるが、吸引側の真空度を高くすることや加圧ピンの数及び配置を適宜選択することにより、上記溶湯凝固ゾーン用空隙やガス排出空隙の設置目的を達成することができる。すなわち、先湯が２段空隙の溶湯凝固ゾーン用空隙で冷却凝固し、溶湯凝固ゾーン用空隙より狭いガス排出空隙やガス排出溝に浸入しない構造に、当業者であれば容易に設計することができる。また、溶湯凝固ゾーン用空隙で先湯を確実に冷却凝固するために、加圧ステムや加圧ピンにベリリューム銅など熱伝導の良い材料を用い、その内部を水冷することができる構造とすることもできる。
【００２４】
本発明の堅型鋳造方法は、本発明の竪型鋳造装置を用いて、真空吸引等により溶湯保持炉からストークを通じて溶湯を金型のキャビテイ内へ鋳込み、溶湯がキャビテイ内を充填し、先湯が２段空隙の溶湯凝固ゾーン用空隙で冷却凝固した後、固定金型に設けられている溶湯流入ゲートを塞ぎ、その後金型キャビテイ内の溶湯を加圧し凝固時にひけ巣の発生がなくかつガスの巻込みのない鋳造品を鋳造することを特徴とするが、加圧ピンの後退位置で、金型キャビテイ内への溶湯の充填を開始し、先湯の流速をキャビテイ第２湯溜部で減速させ、ガス排出空隙又はガス排出溝から金型キャビテイ内のガスを排出させながら、溶湯凝固ゾーン用空隙の先湯を冷却凝固させ、金型キャビテイ内に溶湯が充填された後、１又は複数の加圧ピンを前進させて湯溜部の溶湯を加圧することが好ましく、また、複数の溶湯凝固ゾーンに隣接するガス排出空隙又はガス排出溝から真空ガス抜きを行うことによってガスの巻き込みをより減少せしめると共に、加圧ステム及び複数の加圧ピンにより溶湯を加圧することによって圧力伝達距離を短くすることが好ましい。そして、溶湯が凝固しこれに対する補充充填が完了したら短い冷却時間を経て可動プラテンによって可動金型を上昇させ、これとともに持ち上げられて製品素材を加圧ステム並びに加圧ピン及び押し出しピンで可動金型から押し出し、更に押し出しピンで突き出して加圧ステム、加圧ピンから抜き出して製品素材を取り出し、常法により整形することによりひけ巣の発生やガス巻込みがなく、緻密な組織の鋳造製品を得ることができる。また、かかる動作を毎回繰り返すために、溶湯凝固ゾーン用空隙の凝固溶湯は毎回取り除かれ、ガス排出用通路に目詰まりを起こすことがない。
【００２５】
【実施例】
以下、本発明の実施例を図面により具体的に説明するが、本発明の技術的範囲はこれら実施例に限定されるものではない。なお、図１は本発明の竪型鋳造装置の概略縦断面図、図２は図１のＡ−Ａ断面図、図３は溶湯の吸引状態を示す説明図、図４は図３に続く作動状態を示す説明図、図５は加圧ピンの作動状態のうち溶湯流入前の状態を示す説明図、図６は図５に続く作動状態を示す説明図である。また図１〜図６中、１は固定金型、２は可動金型、５はストーク、９はキャビテイ製品部、１０は円形ゲート、１１はキャビテイ第１湯溜部、１３は閉塞ピン、１４は加圧ステム、１７は溶湯凝固ゾーン用空隙（加圧ステム外周）、１９はキャビテイ第２湯溜部、２０は加圧ピン、２１は溶湯凝固ゾーン用空隙（加圧ピン外周）、２９は加圧ステムガス排出孔、３４は加圧ピンガス排出孔を示す。
【００２６】
図１〜図６に示される本発明の鋳造装置は、上下に移動して型閉型開を行うことができる、鋳造装置下部の水平な固定プラテン３に取り付けられた固定金型１と鋳造装置上部の水平な可動プラテン４に取り付けられた可動金型２と、固定金型１の下方に取り付けられ、その下端が溶湯保持炉６内の溶湯７の湯面８の下に入っている鋳込みストーク５とを備えている。そして、かかる固定金型１と可動金型２とのシールパッキング３５を介しての型閉により、キャビテイ製品部９とキャビテイ第１湯溜部１１とキャビテイ第２湯溜部１９の他、キャビテイ製品部９とキャビテイ第１湯溜部１１とを連通するサイドゲート１２とを備えた金型キャビテイが形成されるようになっている。また、金型の取り付けは、型締めプレス装置（図示せず）の可動プラテン４を引き上げた状態で、シールパッキング３８を介してストーク５を取りつけた固定金型１と可動金型２からなる金型のセットを装入し、固定プラテン３上に置き、可動プラテン４を可動金型２の上面に接触するまで下降させ、固定金型１を固定プラテン３に、可動金型２を可動プラテン４に取り付け、金型キャビテイ内の溶湯に圧力を加えたときの反力によって型が開かない型締力を持った油圧シリンダーで可動プラテン４を押圧することにより行うようになっている。
【００２７】
固定金型１には、金型キャビテイを真空にして溶湯を吸引して湯先を噴出させるための円形ゲート１０が設けられている。キャビテイ内が減圧されると溶湯保持炉６内の溶湯７は大気圧によってストーク５内に押し上げられ、固定金型１の円形ゲート１０を通じてキャビテイ製品部９内に充填される。この時のキャビテイ内の真空度は、溶湯の円形ゲート１０の通過速度が早く噴流となって上方に噴出するように設定されている。また、図３に示すように、キャビテイ第１湯溜部１１の入口直径ｄ₁が円形ゲート１０の径ｄの１．４倍以上に構成され、また加圧ステム１４の外径ｄｓは湯溜部１１の入口直径ｄ₁よりもわずかに小さく構成され、さらにキャビテイ第１湯溜部１１の天井高さは式；ｈ＝ｖ²／２ｇ（式中、ｈは噴流到達高さ、ｖは円形ゲート通過速度、ｇは重力の加速度を示す。）で計算される円形ゲート１０を通過した溶湯噴流１５が到達する高さｈよりも高く構成されている。したがって、充填初期において噴流がキャビテイ第１湯溜部１１の天井に衝突することなく、その上部には溶湯噴流１５の自由表面が形成され、この部分の下降流はなくなるので、溶湯表面のわずかの酸化物は静止状態を保ち、また湯溜部１１の上部に残ったガスを溶湯１６に巻き込むこともなくなる結果、これら円形ゲート１０を通過した溶湯噴流１５の先端にあるわずかな酸化膜、凝固層は全部キャビテイ第１湯溜部１１中に残留し、酸化物やガスの巻き込みのない清浄な溶湯のみがサイドゲート１２を通過してキャビテイ製品部９内に充填されることになる。
【００２８】
円形ゲート１０上方の可動金型２には、シールパッキング２７を介して油圧シリンダ２５が液密に配設されており、該油圧シリンダ２５には油圧により加圧ステム１４をキャビテイ第１湯溜部１１へ進退させることができる加圧ステム用ピストン２３がシールパッキング２７を介して収納されており、該加圧ステム用ピストン２３には円形ゲート１０を閉塞することができる閉塞ピン１３を進退させることができる閉塞ピン用ピストン２４が、加圧ステム用ピストン２３と同軸的に収納されている。金型キャビテイに溶湯の充填が完了した後、閉塞ピン１３をピストン２４によって前進させ、円形ゲート１０を閉塞し、その後直ちに加圧ステム１４をピストン２３によって前進させ、キャビテイ製品部９内の未充填空隙の体積分及び凝固収縮体積分の溶湯をキャビテイ第１湯溜部１１から加圧補給する。その時、加圧ステム１４のストークが大きいので充分量の溶湯を補充及び加圧充填することができる。
【００２９】
加圧ステム１４による加圧の際にも、ストーク５内の湯面にわずかに発生する酸化物、円形ゲート１０入口で冷却されて形成される湯先表面の凝固層や噴流によって発生するガス巻き込み層は、ゲート噴流１５によって全部湯溜部１１の最上部に集まり、加圧ステム１４によって押し出されることなくキャビテイ第１湯溜部１１に残留し、キャビテイ製品部９に流入することはなく、その結果、これらを原因とする鋳造不良は皆無になる。また、加圧ステム１４の外周には、ガス排出孔２９に連通するガス排出空隙１８や溶湯凝固ゾーン用空隙１７からなる２段空隙が設けられている。このガス排出孔２９は、注湯時に真空吸引を行うための真空装置（図示せず）に流量制御バルブ（図示せず）を有する配管を介して連結されている。さらに、溶湯凝固ゾーン用空隙１７で形成された凝固層は、図４ｄに示されるように、製品素材と共に取り出されるので、ガスの真空吸引通路は鋳造の度に確保される。
【００３０】
またキャビテイ製品部９の端部上方には、２つの小さなキャビテイ第２湯溜部１９が形成されており、該湯溜部１９の上方の可動金型２には、油圧シリンダ３１が配設されており、該油圧シリンダ３１には油圧により２つの加圧ピン２０をキャビテイ第２湯溜部１９へ進退させることができる加圧ピン用ピストン３０が収納されている。上記２つの加圧ピン２０は、型開閉方向と平行で型パーテイング面と直交する方向の軸芯を有し、シールパッキング３３を介して可動金型２に液密に設けられている。これら加圧ピン２０の外周にも、ガス排出孔３４に連通するガス排出空隙２２や溶湯凝固ゾーン用空隙２１からなる２段空隙が設けられている。このガス排出孔３４も、注湯時に真空吸引を行うための真空装置に、流量制御バルブを有する配管を介して連結されている。そして、加圧ステム１４によってキャビテイ製品部９内の補充充填を行った後、これら加圧ピン２０を押し出し、キャビテイ第２湯溜部１９を介してキャビテイ製品部９の溶湯を加圧するようになっている。また、加圧ピン２０の外径はキャビテイ第２湯溜部１９の入口の直径よりもわずかに小さく構成されている。これら加圧ピン２０も毎回摺動するので溶湯凝固ゾーン用空隙２１で形成された凝固層は製品素材についた状態で図示されていない押出ピンによって押し出されガス通路穴に残らず、ガスの真空吸引通路は確保されるようになっている。
【００３１】
次に作用について説明する。型締完了後キャビテイ内を、加圧ステム１４及び加圧ピン２０の外周に近接して設けられた溶湯凝固ゾーン用空隙１７，２１、ガス排出空隙１８，２２及びガス排出孔２９，３４を通じて真空吸引することにより減圧し、溶湯１６をストーク５を通じてキャビテイ第１湯溜部１１に吸い上げる。溶湯１６はストーク５を上昇し固定金型１の円形ゲート１０を通過して噴出し（図３）、次いでキャビテイ製品部９内に充填される。一般的に、キャビテイ製品部９内の流動抵抗があるので、加圧ピン下方のキャビテイ第２湯溜部１９に溶湯が到達する前に、円形ゲート１０の上部にあるキャビテイ第１湯溜部１１が溶湯で充填される（図４ａ）が、ガス排出孔２９，３４を通じての真空吸引により、先湯が２段空隙の溶湯凝固ゾーン用空隙１７，２１に入ってくると、通路が狭く、溶湯の熱容量が少なく、反対に冷却面積が大きいので冷却速度が大きく、凝固が進み流動性が低下し、加えて、真空吸引による力はそれ程大きくないことから、溶湯の先端は溶湯凝固ゾーン用空隙１７の途中で停止し、凝固してガス排出空隙１８に浸入することはない。
【００３２】
キャビテイ内の溶湯の流れが停止すると、吸引ガスの流れも停止してガス排出通路等の真空度が高くなるので、これを充填完了の信号として検知して、直ちに閉塞ピン１３を前進させて円形ゲート１０を挿入閉塞する（図４ｂ）。このようにキャビテイ製品部９及びキャビテイ第１湯溜部１１内の溶湯がストーク５に逆流しないように閉塞した後、直ちに加圧ステム１４を進出させ加圧し、キャビテイ第１湯溜部１１内の半凝固状態の溶湯をキャビテイ製品部９に補充充填する（図４ｃ）。充填が完了し冷却が始まると、溶湯１６の凝固収縮が生起するため、加圧ステム１４に高圧力を加えて進出させ、凝固収縮体積に応じた補充を行う。閉塞ピン１３による円形ゲート１０の閉塞時、閉塞ピン１３と円形ゲート１０との接触が仮に完全で無くても、小さい空隙に存在する溶湯は早く冷却凝固し、溶湯が円形ゲート１０からのストーク５に逆流することなく、また、ゲート１０及びストーク５内の溶湯は真空による引き上げ力がなくなり保持炉に落下する。
【００３３】
加圧ステム１４による補充充填の場合は抵抗も小さく、加圧ステム１４の加圧シリンダーの力も小さくて済み、油圧シリンダー内の油圧も低い状態で進出させることができる。この加圧ステム１４の進出による補充充填により、溶湯がキャビテイ製品部９及びキャビテイ第２湯溜部１９を補充充填した後（図６ａ）、加圧ピン２０を進出させることになる（図６ｂ）。かかる加圧ピン２０による加圧は、加圧ステム１４による充填完了とともに流動抵抗が増大し油圧が上昇するので、これを検知して開始される。加圧ステム１４の進出による凝固収縮体積に応じた補充は、キャビテイ製品部９の反対側の端部までは圧力伝達が難しいので、端部周辺の加圧ピン２０を作動させて加圧し、全面的に凝固凝縮によるひけ巣のない緻密な組織の製品を得ることができる。キャビテイ製品部９内の溶融金属の冷却凝固が完了した後、型開きを行い可動金型で持ち上げられた製品素材は各加圧ピン及び押し出しピンによって押し出され取り出すことができる（図４ｄ、図６ｃ）。
【００３４】
【発明の効果】
本発明の鋳込装置を用いる場合、加圧ステム及び加圧ピン外周のガス排出系の構造は単純であり、運転中のトラブルの発生は少なくなる。特に真空吸引機構を用いると、溶湯の先湯は真空吸引力だけで狭い溶湯凝固ゾーン用空隙に流入するのでそこで凝固し停止して、ガス排出空隙通路に浸入することはない。また、キャビテイ第１湯溜部の深さを深くしたことにより、加圧ステムのストークを長くすることができ、キャビテイ製品部内の補充充填及び凝固収縮に対して充分な体積の溶湯を加圧ステムによって圧入して、より緻密な組織で強度のある鋳造品を得ることができる。また、円形ゲートの内径よりもわずかに小径の閉塞ピンで円形ゲートを閉塞させることによって、ストーク内の溶湯を早く保持炉に戻すとともに製品の取り出しを容易にすることができる。
【００３５】
また、真空吸引機構を備えた本発明の鋳込装置を用いる場合、金型キャビテイに溶湯を充填するとき、真空で吸引するために高圧射出装置を必要とせず、充填後、円形ゲートを閉塞して小さな圧力で必要充分な加圧をすることができるので、従来の高圧法の１／３〜１／５の型締力で対応でき、鋳造装置のコストが大幅に安くなり、鋳造品のコストを大幅に引き下げることができる。また、溶湯を保持炉から直接吸引するので酸化物が発生することもなく、その通路が短いことによって凝固層の発生も少なく、円形ゲートの出口に適当な高さを持つキャビテイ第１湯溜部を設けることによって噴流が天井に衝突することもなく、ガスの巻き込みをなくすとともに、わずかに残った酸化物や凝固層をキャビテイ第１湯溜部に滞留させることができ、その結果不純物の無い緻密な組織の鋳造品を得ることができる。さらに、溶湯のキャビテイへの充填を真空吸引のみで行う場合は、低圧鋳造のように溶湯保持炉を密閉することもないので、設備費が安くなるだけでなく、湯面を高くし、ストークを短くできるなど装置の配置、運転も容易になる。
【図面の簡単な説明】
【図１】本発明の竪型鋳造装置の概略縦断面図である。
【図２】図１のＡ−Ａ断面図である。
【図３】本発明の竪型鋳造装置における溶湯の吸引状態を示す説明図である。
【図４】図３に続く本発明の竪型鋳造装置における作動状態を示す説明図である。
【図５】本発明の竪型鋳造装置における加圧ピンの作動状態のうち溶湯流入前の状態を示す説明図である。
【図６】図５に続く本発明の竪型鋳造装置における作動状態を示す説明図である。
【符号の説明】
１固定金型
２可動金型
３固定プラテン
４可動プラテン
５ストーク
６溶湯保持炉
７，１６溶湯
８湯面
９金型キャビテイ
１０円形ゲート
１１キャビテイ第１湯溜部
１２サイドゲート
１３閉塞ピン
１４加圧ステム
１５噴流
１７加圧ステム溶湯凝固ゾーン用空隙
１８加圧ステムガス排出空隙
１９キャビテイ第２湯溜部
２０加圧ピン
２１加圧ピン溶湯凝固ゾーン用空隙
２２加圧ピン外周ガス排出空隙
２３加圧ステム用ピストン
２４閉塞ピン用ピストン
２５油圧シリンダ
２６圧力油入口ａ，ｂ，ｃ
２７加圧ステムシールパッキング
２８閉塞ピンシールパッキング
２９加圧ステム排出通路
３０加圧ピンピストン
３１加圧ピン油圧シリンダ
３２圧力油入口
３３加圧ピンシールパッキング
３４加圧ピンガス排出通路
３５金型シールパッキング
３６加圧ステム冷却水穴
３７加圧ピン冷却水穴
３８ストークシールパッキング[0001]
BACKGROUND OF THE INVENTION
The present invention is capable of casting a cast product such as an aluminum alloy that does not generate a shrinkage nest during solidification and that does not entrain gas, and is a solid mold that fills a mold cavity from below, particularly vacuum suction filling. The present invention relates to a casting apparatus and a solid casting method using the same.
[0002]
[Prior art]
When casting a cast product such as a light alloy product, particularly a part that requires strength, a solid die casting machine is generally used in order to prevent gas from being entrained during casting of the molten metal. For example, for a method of manufacturing an aluminum wheel for automobiles, etc., as described in Japanese Patent Publication No. 3-4297, a molten metal inflow gate having a diameter smaller than a sleeve diameter for introducing the molten metal into the mold cavity, Although a casting method using a pressure pin having a diameter slightly smaller than the inner diameter of the gate is already known, it is not possible to sufficiently prevent the shrinkage nest that occurs during the solidification of the molten metal. It was not always sufficient to prevent the entrainment.
[0003]
As a vertical casting method for preventing mixing of oxides and gas entrainment when casting a general part, the inventor has a lower fixed mold, an upper movable mold, and a lower side of the fixed mold. In the fixed mold, a vertical circular gate having a smaller diameter than the inner diameter of the casting sleeve is provided, and a pin having a diameter slightly smaller than the inner diameter of the circular gate is inserted into the movable gate. A molten metal jet that is slidably provided on the mold so that pins can be moved up and down in the circular gate, and the diameter of the inlet of the circular reservoir provided on the upper part of the circular gate of the movable mold is ejected from the circular gate during casting The mold is cast into the cavity of the mold using a solid casting device in which the ceiling height of the reservoir is higher than the arrival height of the molten metal jet, and the pin is filled when the molten metal fills the cavity. To make the hot water action by projecting Proposed (JP-A-10-146663). Although this method is excellent in that it can prevent the contamination of oxides, the entrainment of gas, or the shrinkage nest that occurs at the time of solidification of molten metal, it can sufficiently prevent the formation of a nest that occurs at the time of gas entrainment or solidification of the melt. It could not be said that there was no problem at all.
[0004]
In addition, the casting methods described in the above Japanese Patent Publication No. 3-4297 and Japanese Patent Laid-Open No. 10-146663 require large radiant power and clamping force for high-pressure casting, and costly equipment is required. It had been. On the other hand, low-cost casting methods include low pressure casting methods and vacuum suction casting methods (Japanese Patent Laid-Open Nos. 58-55166, 5-212528, 6-218220, and 7-32125). Japanese Patent Laid-Open No. 9-57422) is known, but it is not possible to sufficiently prevent sinkholes that occur during mixing of oxides, gas entrainment, or solidification, and to cast products that require strength. Was not applied. Further, for example, in the above-mentioned JP-A-58-55166, the hot water tank upper space is depressurized and the inside of the cavities is depressurized via an air vent valve, and then the hot water tank upper space is pressurized and the molten metal is cast into the cavities. By using a complicated switching valve or valve, or by depressurizing the hot water bath upper space, the gas in the cavities is exhausted through the stalk and hot water bath, and then the hot water bath upper space is pressurized to bring the molten metal into the cavities. Various methods have been devised for extracting gas from the cavities as disclosed in the method of mixing gas into the molten metal in addition to using complicated switching valves and valves for casting. However, there were many problems in operation, and there was not always satisfactory in practical use until now.
[0005]
[Problems to be solved by the invention]
In casting with a solid die-casting machine, the oxide on the surface of the molten metal poured into the sleeve that causes product defects, the chill layer generated by cooling on the sleeve inner surface, that is, the mixing of the solidified layer into the product is prevented, In order to prevent gas entrainment in the gate part and to prevent shrinkage caused by solidification shrinkage, the gas in the cavity is almost completely discharged, and at the same time, a sufficient amount of molten metal is effectively pressurized and replenished. There is a need. At that time, it is also necessary to simplify the structure of the cavity and the entire structure of the casting apparatus in order to reduce trouble during operation. An object of the present invention is to provide a cast product that can exhaust gas in the cavity almost completely and at the same time effectively pressurize the molten metal in the closed cavity without generating a sinkhole and entraining gas. An object of the present invention is to provide a vertical casting apparatus having a simple structure and a low cost for casting, and a vertical casting method using the vertical casting apparatus.
[0006]
[Means for Solving the Problems]
The present inventor has eagerly studied to solve the above problems, and casts the molten metal by discharging the gas in the cavity and discharges the gas from the gas discharge passage, and at the same time for the molten metal solidification zone connected to the gas discharge passage. If the molten metal is confined in the cavity by a simple means of solidifying the hot water in the gap, and if the molten metal in such a closed state is effectively pressurized by shortening the pressure transmission distance at multiple locations, there will be no generation of shrinkage and an oxide film The present inventors have found that it is possible to cast a cast product that is free from gas contamination and gas entrainment.
[0007]
That is, the present invention provides a gas discharge passage.And a molten metal solidification zone gap communicating with the gas discharge passage provided in the vicinity of the gas discharge passageA lower fixed mold and an upper movable mold capable of forming a mold cavity including: a casting means for supplying and filling molten metal from below into the mold cavity; and a mold by the casting means. Closing means for closing the molten metal inflow gate provided in the stationary mold after the molten metal cast into the mold cavity is filled, and pressurizing means for pressurizing the molten metal in the closed mold cavity Vertical casting apparatus withThe mold cavity includes a cavity product section and a cavity hot water reservoir, and the cavity hot water reservoir is located above the molten metal inflow gate, and the cavity of the cavity product portion. A vertical casting apparatus comprising one or two or more cavities of second hot water reservoirs located above the vicinity of the end opposite to the first hot water reservoir.(Claim 1)A lower fixed mold and an upper movable mold capable of forming a mold cavity having a gas discharge path and a molten metal solidification zone gap communicating with the gas discharge path provided in the vicinity of the gas discharge path; A casting means for supplying and filling molten metal into the mold cavity from below, and the molten metal cast into the mold cavity by the casting means is provided in the fixed mold after filling the cavity. A vertical casting apparatus having a closing means for closing a molten metal inflow gate and a pressurizing means for pressurizing the molten metal in the closed mold cavity, and closing the molten metal inflow gate provided in the fixed mold. The closing means includes a closing pin that can open and close the circular molten metal inflow gate, and the diameter of the insertion portion of the closing pin to the circular molten metal inflow gate is configured to be slightly smaller than the inner diameter of the circular molten metal inflow gate, Vertical casting apparatus characterized by being configured to be smaller than the circular melt inflow gate inside diameter inside diameter of the casting for stalk disposed on the lower side of the fixed mold was(Claim 2) andPressurizing means for pressurizing the molten metal in the closed mold cavity, ( 1 ) A pressure stem that is slidably disposed in a movable mold above the first hot water reservoir, and / or has a closing pin slidably provided at the center thereof; and / or ( 2 ) 2. The vertical casting apparatus according to claim 1, further comprising one or more pressure pins slidably disposed on a movable mold above the second hot water reservoir.(Claim 3) andThe pressure stem and the closing pin are arranged on the movable mold above the circular molten metal inflow gate, and the diameter of the inlet of the circular cavities first hot water reservoir formed in the state where they are raised is the diameter of the circular molten metal inflow gate. So that the height of the ceiling of the cavity first hot water reservoir in the ascending limit of the pressurizing stem and the closing pin is 10 mm higher than the height of the molten metal jet ejected from the circular molten metal inflow gate. 4. A vertical casting apparatus according to claim 3, wherein(Claim 4) andThe casting means for filling the mold cavities with the molten metal from the lower side sucks the gas in the mold cavities by vacuum suction, and through the casting stalk provided on the lower side of the fixed mold, the lower molten metal holding furnace A vertical casting apparatus according to any one of claims 1 to 4, further comprising a vacuum suction mechanism for vacuum-filling molten metal from(Claim 5),The vertical casting apparatus according to any one of claims 1 to 5, wherein a gap for a molten metal solidification zone communicating with the gas discharge passage is provided close to the pressurizing means.(Claim 6),A molten metal solidification zone gap communicating with a gas discharge passage provided close to the pressurizing means is formed between the outer peripheral surface of the pressurization stem and / or the pressurization pin and the inner peripheral surface of the movable mold. 7. The vertical casting apparatus according to claim 6, wherein the vertical casting apparatus communicates with the gas discharge hole through a gas discharge gap or a gas discharge groove.(Claim 7)It is provided concentrically with the pressure stem and / or the pressure pin, and is 1-5 than the diameter of the pressure stem and / or the pressure pin. mm 10-40 for large internal diameter mm A melt solidification zone gap and a gas discharge gap having a certain depth are provided concentrically with the pressure stem and / or the pressure pin, and 0.4 to 1. 0 mm 8. A vertical casting apparatus according to claim 7, further comprising a gas discharge gap having a large inner diameter, or a gas discharge groove extending in an axial line on an outer peripheral surface of the pressure stem and / or the pressure pin.(Claim 8)Related.
[0008]
The present invention also providesUsing the vertical casting apparatus according to any one of claims 1 to 8, the molten metal is cast into the cavity of the mold through the stalk from the molten metal holding furnace, and after the molten metal is filled in the cavity, the fixed mold is provided. A solid casting method characterized in that the molten metal inflow gate is closed, and then the molten metal in the mold cavity is pressurized to cast a cast product that does not generate a sinkhole and does not entrain gas during solidification.(Claim 10)Related.As a preferable solid casting method, the vertical casting apparatus of the present invention is used to start filling the mold cavities with the molten metal at the retracted position of the pressure pin, and to adjust the flow rate of the prior hot water to the cavities. 2Decelerate at the hot water reservoir, cool and solidify the molten metal in the molten metal solidification zone gap while discharging the gas in the mold cavity through the gas discharge gap or gas discharge groove, and fill and seal the molten metal in the mold cavity After that, the pressure pin is moved forward to pressurize the molten metal in the cavitating second hot water reservoir, or the gas is removed by vacuum degassing from the gas discharge gaps or gas discharge grooves adjacent to the plurality of molten metal solidification zones. To illustrate the method of reducing the entrainment and shortening the pressure transmission distance by pressurizing the molten metal from the pressure stem and the plurality of pressure pins, and the method in which the cast product is a cast product of light metal alloy It can be.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The vertical casting apparatus of the present invention supplies a lower fixed mold and an upper movable mold capable of forming a mold cavity having a gas discharge passage, and supplies and fills molten metal into the mold cavity from below. Casting means that can be used, and a closing means that can block the molten metal inflow gate provided in the fixed mold after the molten metal cast into the mold cavity is filled by the casting means. And a pressurizing means capable of pressurizing the molten metal in the closed mold cavity, characterized in that a molten metal solidification zone gap communicating with the gas discharge passage is provided in the vicinity of the gas discharge passage, When the vertical casting apparatus of the present invention is used, it is possible to cast a cast product which does not generate a shrinkage nest during solidification and does not involve gas. And although it does not specifically limit as this casting, A light metal alloy, especially an aluminum alloy with a large solidification shrinkage are preferable. Since aluminum shrinks by about 7% when it solidifies, the casting apparatus and casting method of the present invention that can prevent the formation of shrinkage nests, when casting from a molten metal made of a light metal alloy having a large solidification shrinkage, such as an aluminum alloy, It can be applied particularly advantageously.
[0010]
As the mold cavity, a molten metal can be charged and supplied from below, and at least the gas existing in the cavity can be discharged when the molten metal is filled in the mold cavity, and the gas discharge path Although it will not be restrict | limited especially if it has the space | gap for molten metal solidification zones which connected, The cavity 1st provided with a cavity product part and a cavity hot water storage part, and this cavity hot water storage part is located above a molten metal inflow gate. What consists of a hot water reservoir part and the 1 or 2 or more cavity 2nd hot water reservoir part located in the upper part vicinity vicinity of the opposite side to the cavity 1st hot water reservoir part of the said cavity product part is preferable. And the cavity product part and the cavity 1st hot water reservoir are connected via the side gate, and the cavity 1st hot water reservoir has a larger volume than usual compared with the cavity 2nd hot water reservoir. . Examples of the gas discharge passage include a gas discharge hole penetrating through the movable mold and a gas discharge gap or a gas discharge groove.
[0011]
In the vertical casting apparatus of the present invention, conventionally known casting means can be used as casting means for supplying and filling molten metal such as molten aluminum into the mold cavities from below. Injecting means having a plunger for high-pressure or low-pressure casting as described in JP-A-4297 or JP-A-10-146663, or as described in JP-A-58-55166 Although there can be mentioned low-pressure casting means equipped with a pressurizing mechanism that applies gas pressure to the surface of the molten metal in a sealed water bath, prevention of gas entrainment at the time of filling the molten metal, low equipment cost and simple structure A vacuum suction mechanism that can be configured by the above, i.e., by vacuum suction of the gas in the mold cavity, the casting stalk provided adjacent to the lower side of the lower fixed mold is passed through. Te, preferably cast means comprises a vacuum suction mechanism for vacuum filling a molten metal from the molten metal holding furnace below. In this case, the tip of the molten metal to be injected is at the same level as the molten metal surface of the molten metal holding furnace until the start of pouring, and the stalk length is short even when casting is started by vacuum and is solidified because it is heated. There is little generation of a layer, and there is no generation of defects due to mixing of the solidified layer. In addition, filling of hot water supply by vacuum suction does not require a hermetic seal of the molten metal holding furnace as in low pressure casting by pressurizing the molten metal surface, and the shape of the molten metal holding furnace can be made free, and only around the stalk. By making the shape narrow, the hot water surface of the molten metal can be brought close to the mold to facilitate hot water supply.
[0012]
The lower fixed mold is formed with a communicating portion between the casting stalk or sleeve for filling and supplying the molten metal into the cavity from below, and the cavity first hot water reservoir, and the molten metal is formed in the communicating portion. An inflow gate is provided. The shape of the molten metal inflow gate is not particularly limited, but a shape having a circular cross section is preferable in view of easiness of processing. In this case, the inner diameter of the circular molten metal inflow gate is smaller than the inner diameter of the casting stalk. It is preferable to configure as described above. By configuring in this way, the molten metal filled and supplied from below can be ejected into the cavity first hot water reservoir, and, as will be described later, in the casting stalk that contributes to defective casting products. It is possible to prevent the oxide film on the surface of the molten metal or the chill layer (solidified layer) generated by cooling on the inner surface of the stalk from entering the product.
[0013]
After the molten metal cast into the mold cavity by the casting means fills the cavity, the closing means in the present invention for closing the molten metal inflow gate provided in the fixed mold is closed the molten metal inflow gate. Any mechanism may be used as long as it has a mechanism that can be used. For example, a blocking pin disposed above the gate that can open and close the circular molten metal inflow gate can be specifically mentioned. The diameter of the insertion portion of the closing pin into the circular molten metal inflow gate is preferably slightly smaller than the inner diameter of the circular molten metal inflow gate in view of the closed sealing performance. It is preferable to hold the closing pin so that it can move forward and backward in a liquid-tight manner with respect to the movable mold. In the case of being held slidably densely, a closing pin can be provided coaxially and slidably in a liquid-tight manner at the center of the pressure stem.
[0014]
As described above, when the pressurizing stem and the closing pin are disposed in the movable mold above the circular molten metal inflow gate, the circular cavity first hot water reservoir portion formed in a state where they are retracted (raised). The diameter of the inlet is made larger than 1.4 times the diameter of the circular molten metal inflow gate, and the height of the ceiling of the hot water reservoir at the upper limit of the pressure stem and the closing pin is ejected from the circular molten metal inflow gate. It is preferable that the cavity first hot water reservoir is configured to be 10 mm or more higher than the height of the molten metal jet. Thus, when the diameter of the inlet of the hot water reservoir is set to be 1.4 times or more of the diameter of the circular gate, the height h of the molten metal jet is v when the passing speed of the molten metal at the circular gate is v and the acceleration of gravity is g. , H = v²/ 2g can be calculated by the formula, so if the ceiling height of the cavitity first basin is about 1.5 times the inlet diameter of the basin, the casting speed can be increased within a general range. Even so, the ceiling of the first hot water reservoir will be 10 mm higher than the height of the molten metal jet ejected from the circular molten metal inflow gate, and the molten metal jet will not collide with the ceiling surface. Entrainment can also be prevented.
[0015]
For example, the hot water supply / filling speed of the molten metal varies depending on the shape of the product, but in general, the passing speed in the circular gate is preferably 1.0 to 2.0 m / sec. In that case, the jet height from the circular gate is usually When the height of the ceiling of the cavitity first hot water reservoir is 10 mm or more higher than the height of the molten metal jet, the free surface is formed and the oxide remaining on the hot water surface is also on the surface. The remaining gas and the gas remaining in the upper part of the hot water reservoir are not contained in a downward flow, and further, the gas is discharged from the gap around the pressurization stem in a vacuum, so that the gas may be involved in the molten metal. Absent. On the other hand, if the jet velocity is too slow, it will not collide with the ceiling and gas entrainment will decrease, but the casting time will become longer, the velocity at which the molten metal will flow through the cavity product will become slower, during which cooling solidification will progress, However, even if the pressure is applied, the pressure transmission is poor and the possibility of occurrence of shrinkage is increased. Therefore, it is preferable to make the casting speed as fast as possible. For this reason, it is preferable to increase the ceiling height of the cavity first hot water reservoir. And if the ceiling of the cavity 1st hot water reservoir is raised and its volume increased, the vacuum suction force will be weakened, and there may be a case where the molten product is insufficiently filled in the narrow space in the cavity product section. Even if there is, there is no problem because it can be replenished and filled with sufficient pressure such as a pressure stem.
[0016]
Even when high pressure or low pressure casting is employed by forming the cavity first hot water reservoir in the cavity as described above, the hot water reservoir is used when the closing pin or the pressure stem is advanced (lowered). The oxide or gas entrainment layer present at the uppermost portion of the gas stays in the cavity first hot water reservoir without being pushed out, and does not enter the cavity product part. In particular, when employing vacuum suction casting, as mentioned above, the stalk for hot water supply is located below the surface of the molten metal holding furnace, and the oxide film generated on the surface of the molten metal floats on the surface of the molten metal. Although it does not enter the stalk, the hot water surface in the stalk may be slightly oxidized by the air entering through the mold, but this small amount of oxide film is located at the tip of the jet and is the first hot water reservoir in the cavity. It will not go all the way into the cavities and will flow out to the cavity product part through the side gate, so that no oxide will be mixed into the cast product, so there will be no defects in the cast product and variations in strength. .
[0017]
Next, by pressurizing the molten metal filled in the closed mold cavities, it is possible to cast a cast product in which no shrinkage occurs at the time of solidification and in which no gas is involved by the jet. As a pressurizing means for pressurizing the molten metal in the closed mold cavity, it is slidably provided on the movable mold above the first hot water reservoir of the cavity, and a closing pin is slidable in the center. The pressurizing stem provided and the cavity first hot water reservoir are slidably disposed on the movable mold above the cavity second hot water reservoir located at a position separated from the cavity product portion. A pressure pin can be specifically exemplified. A plurality of pressure pins are preferably provided, and the diameter thereof is preferably 2/3 to 1 times the depth of the cavity second hot water reservoir. Further, these pressure stems and pressure pins are preferably used in combination. In this way, by pressurizing the molten metal from the pressure stem and the plurality of pressure pins located at separate positions, the pressure transmission distance to the molten metal in the cavity is shortened, so that the pressure is uniformly transmitted to the cavity product part. Therefore, it is possible to cast a cast product in which no shrinkage occurs during solidification with a small pressure. As a result, it becomes possible to cast a cast product having a dense structure with a casting apparatus having a small mold clamping force. In addition, by placing the pressure stem and pressure pin at appropriate positions according to the form of the product, the pressure transmission distance of the molten metal in the cavity product part is further shortened, and the pressure transmission is made more uniform and sufficient. In addition, it is possible to prevent the formation of a shrinkage nest with a smaller pressure.
[0018]
In conventional casting apparatuses, in general, in order to cast a cast product in which no shrinkage occurs during solidification, the pressurizing means of the molten metal by the pressurizing means is increased and rapidly pressurized. In this case, the pressure transmission is too good, the mold opening force becomes large, burrs are blown, and the mold clamping force needs to be increased. On the other hand, if the pressurization rate is slowed down, a shrinkage nest will occur without catching up with the solidification shrinkage of the melt. On the other hand, according to the present invention, it is possible to cast a cast product that does not generate a shrinkage nest at the time of solidification with a small pressurizing pressure. Therefore, by detecting the mold opening force and adjusting the pressurizing speed to a predetermined speed, Uniform and sufficient pressure transmission can be performed even with a small clamping force that can prevent the above. As described above, in the present invention, the pressurization speed is controlled by, for example, performing program control so that the advancement speed of the pressurization stem and the pressurization pin during pressurization becomes a speed adapted to the solidification contraction speed of the molten metal in the cavity product part. By adjusting it, it is possible to prevent the formation of sink marks while preventing burrs from being blown with a press machine with a small clamping force. For example, the pressure and pressurization speed for the molten metal during solidification shrinkage where Pascal's principle does not work Is controlled in accordance with the solidification rate within a range where no burrs are blown, so that a device with a small clamping force of 1/3 to 1/5 of the conventional high pressure method can be used. It is possible to obtain a cast product having a dense structure without gas entrainment.
[0019]
In addition, in the case of a vertical die casting method such as squeeze casting, if the pressure by the acurad pin (center pin) is accelerated, the casting plunger will be pushed down, so that the time will be delayed a little, that is, the gate part will solidify, Since pressure is applied after the pressure transmission to the casting plunger is reduced, solidification of the molten metal in the cavity also progresses, and a large pressure is required to replenish the molten metal. Sometimes. In contrast, in the present invention, since the means for closing the molten metal inflow gate is provided, the molten metal can be replenished and filled from the stage where the progress of solidification is still small, and the pressurized stem and the predetermined position can be filled. Since the pressure is applied by a plurality of pressure pins arranged in the, the pressure transmission distance is short, and uniform and sufficient replenishment filling can be performed with a small pressure. As a result of the pressurization pressure being reduced in this way, the mold clamping force of the mold can be reduced, and the cost of the mold clamping apparatus and the mold can be kept low. Moreover, since this casting speed and pressurization start speed are faster than squeeze casting, the production cycle time is shortened and the productivity is improved.
[0020]
In the present invention, it is important to provide a molten metal solidification zone gap in communication with the gas discharge passage in the vicinity of the gas discharge passage, particularly to provide a molten metal solidification zone gap in communication with the gas discharge passage in the vicinity of the pressurizing means. Features. As the molten metal solidification zone gap, for example, after the gas in the cavities is discharged from the gas discharge passage by vacuum suction or the like, the molten metal can be solidified in the gap that becomes the molten metal solidification zone. Any void can be used as long as it can easily seal and close the inside of the cavity, and the air vent valve, the filter, etc. are disposed by simply providing such a void for the molten metal solidification zone. The inside of the cavities can be easily sealed and closed without using complicated switching valves and valves, and complicated operations such as pressure adjustment are not required when the casting machine is in operation, and there is no breakdown. It can be said that the casting apparatus of the present invention is extremely practical.
[0021]
Further, the molten metal solidification zone gap communicating with the gas discharge passage provided in the vicinity of the pressurizing means is provided between the outer peripheral surface of the pressurization stem and / or the pressurization pin and the inner peripheral surface of the movable mold. Examples of the molten metal solidification zone void that communicates with the gas discharge hole through the gas discharge void or the gas discharge groove to be formed include the pressure stem and / or the pressurization. Specific examples of voids that are provided concentrically with the pin and become a molten metal solidification zone having an inner diameter 1 to 5 mm larger than the diameter of the pressure stem and / or the pressure pin and a depth (length) of about 10 to 40 mm. can do. In this way, by setting the outer diameter of each hot water pool portion to be slightly larger than the outer diameters of the pressure stem and the pressure pin, the solidified layer formed on the outer peripheral wall of each hot water pool portion is inside the product. The pressure resistance of the pressure stem and the pressure pin can be reduced. As described above, if the gap for the molten metal solidification zone is designed and manufactured to a size suitable for the temperature of the molten metal and the casting speed, the hot water is cooled and solidified in the gap when the molten metal is filled. It does not enter the discharge gap or gas discharge groove. The gap for the molten metal solidification zone can be provided not only in a vacuum casting method but also in a casting apparatus using a normal low pressure casting method or a die casting method.
[0022]
The gas discharge gap or gas discharge groove adjacent to the melt solidification zone gap is preferably of a size that does not allow the hot water to flow in or a structure that does not allow the hot water to flow. For example, the gas discharge gap may include a pressurized stem and / or Alternatively, a gas discharge gap that is provided concentrically with the pressure pin and has an inner diameter that is approximately 0.4 to 1.0 mm larger than the diameter of the pressure stem and / or the pressure pin can be specifically mentioned as the gas discharge groove. Can specifically include a gas discharge groove extending in an axial line on the outer peripheral surface of the pressure stem and / or the pressure pin. In order to prevent air from entering when vacuuming the mold cavity, seal packing is installed without providing gas discharge holes and gas discharge passages such as gas discharge gaps or gas discharge grooves on the parting surface. In addition, it is preferable to install a gas discharge passage at a high cavity position where gas tends to remain, for example, above the hot water reservoir. Moreover, it is preferable to install seal packing on the pressure stem and the sliding portion of each pressure pin to prevent air leakage from the outside of the mold.
[0023]
By the way, by setting the degree of vacuum in the cavity to about 2000 to 4000 mm, the filling speed of the molten metal can be set to 1.0 to 2.0 m / second as described above. The air resistance in the two-stage gaps such as the molten metal solidification zone gap and gas discharge gap provided close to the outer periphery of the pressure stem and pressure pin is increased, but the vacuum level on the suction side is increased and the pressure is increased. By appropriately selecting the number and arrangement of the pins, the installation purpose of the molten metal solidification zone gap and the gas discharge gap can be achieved. In other words, those skilled in the art can easily design a structure in which the hot water is cooled and solidified in the melt solidification zone gap of the two-step gap and does not enter the gas discharge gap or gas discharge groove narrower than the melt solidification zone gap. it can. Also, in order to cool and solidify the hot water in the gap for the molten metal solidification zone, a material with good heat conduction, such as beryllium copper, is used for the pressure stem and pressure pin, and the inside can be cooled with water. You can also.
[0024]
The solid casting method of the present invention uses the vertical casting apparatus of the present invention to cast a molten metal into a mold cavity through stalk from a molten metal holding furnace by vacuum suction or the like, and the molten metal fills the interior of the cavity. After cooling and solidifying in the gap for the molten metal solidification zone of the two-stage gap, the molten metal inflow gate provided in the fixed mold is closed, and then the molten metal in the mold cavity is pressurized so that no shrinkage occurs during solidification and gas It is characterized by casting a cast product that is not entrained, but at the retreat position of the pressure pin, filling of the molten metal into the mold cavities is started, and the flow rate of the pre-heated water is measured at the second hot water reservoir portion of the cavities. Decelerate and discharge the gas in the mold cavities from the gas discharge gap or gas discharge groove, cool and solidify the hot water in the gap for the molten metal solidification zone, and then fill the mold cavities with the molten metal. Advance the pressure pin It is preferable to pressurize the molten metal in the hot water reservoir, and further reduce the entrainment of gas by performing vacuum degassing from the gas discharge gap or gas discharge groove adjacent to the plurality of molten metal solidification zones, and pressurization stem It is preferable to shorten the pressure transmission distance by pressurizing the molten metal with a plurality of pressure pins. When the molten metal is solidified and replenishment filling is completed, the movable mold is raised by the movable platen after a short cooling time, and the movable mold is lifted together with the movable mold by the pressure stem, the pressure pin and the extrusion pin. And extruding with an extruding pin, then extracting from the pressurizing stem and pressurizing pin, taking out the product material, and shaping it by a conventional method to obtain a cast product with a dense structure without generation of shrinkage and gas entrainment be able to. Further, since this operation is repeated each time, the molten metal in the molten metal solidification zone gap is removed each time, and the gas discharge passage is not clogged.
[0025]
【Example】
Examples of the present invention will be specifically described below with reference to the drawings. However, the technical scope of the present invention is not limited to these examples. 1 is a schematic longitudinal cross-sectional view of the vertical casting apparatus of the present invention, FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1, FIG. 3 is an explanatory view showing a suction state of the molten metal, and FIG. FIG. 5 is an explanatory diagram showing the state before the molten metal flows in the operating state of the pressure pin, and FIG. 6 is an explanatory diagram showing the operating state following FIG. 1 to 6, 1 is a fixed mold, 2 is a movable mold, 5 is a stalk, 9 is a cavity product section, 10 is a circular gate, 11 is a cavity first hot water reservoir, 13 is a closing pin, 14 Is a pressure stem, 17 is a gap for molten metal solidification zone (outside of the pressure stem), 19 is a cavity second hot water reservoir, 20 is a pressure pin, 21 is a gap for molten metal solidification zone (outside of the pressure pin), 29 is A pressurized stem gas discharge hole 34 indicates a pressurized pin gas discharge hole.
[0026]
The casting apparatus of the present invention shown in FIGS. 1 to 6 can be moved up and down to open the mold, and the fixed mold 1 and the casting apparatus attached to the horizontal fixed platen 3 at the bottom of the casting apparatus. A movable mold 2 attached to the upper horizontal movable platen 4 and a cast stalk attached to the lower side of the fixed mold 1 and having a lower end thereof below the surface 8 of the molten metal 7 in the molten metal holding furnace 6. And 5. Then, by closing the mold between the fixed mold 1 and the movable mold 2 via the seal packing 35, the cavity product part 9, the cavity first hot water reservoir part 11, the cavity second hot water reservoir part 19 and the cavity product are obtained. A mold cavity including a side gate 12 communicating with the portion 9 and the cavity first hot water reservoir 11 is formed. In addition, the mold is attached by a mold composed of a fixed mold 1 and a movable mold 2 to which a stalk 5 is attached via a seal packing 38 in a state where the movable platen 4 of a mold clamping press device (not shown) is pulled up. A set of molds is inserted, placed on the stationary platen 3, the movable platen 4 is lowered until it contacts the upper surface of the movable mold 2, and the fixed mold 1 is moved to the fixed platen 3 and the movable mold 2 is moved to the movable platen 4. The movable platen 4 is pressed by a hydraulic cylinder having a clamping force that prevents the mold from opening due to a reaction force when pressure is applied to the molten metal in the mold cavity.
[0027]
The fixed mold 1 is provided with a circular gate 10 for vacuuming the mold cavity to suck the molten metal and eject the molten metal tip. When the inside of the cavity is depressurized, the molten metal 7 in the molten metal holding furnace 6 is pushed up into the stalk 5 by the atmospheric pressure and filled into the cavity product portion 9 through the circular gate 10 of the fixed mold 1. The degree of vacuum in the cavity at this time is set so that the molten metal passes through the circular gate 10 at a high speed and jets upward. Further, as shown in FIG. 3, the inlet diameter d of the cavity first hot water reservoir 11.₁Is configured to be 1.4 times or more the diameter d of the circular gate 10, and the outer diameter ds of the pressurizing stem 14 is the inlet diameter d of the hot water reservoir 11.₁The ceiling height of the cavity first hot water reservoir 11 is an expression; h = v²/ 2 g (where h is the jet arrival height, v is the circular gate passage velocity, and g is the acceleration of gravity), and the height h reached by the molten jet 15 passing through the circular gate 10 is reached. Highly structured. Accordingly, in the initial stage of filling, the jet does not collide with the ceiling of the cavity first hot water reservoir 11, and the free surface of the molten metal jet 15 is formed on the upper part, and the downward flow in this part is eliminated, so The oxide remains stationary, and the gas remaining on the upper part of the hot water reservoir 11 is not entrained in the molten metal 16. As a result, a slight oxide film or solidified layer at the tip of the molten metal jet 15 passing through the circular gate 10 is obtained. All remain in the cavity first hot water reservoir 11, and only the clean molten metal free from oxides and gases is passed through the side gate 12 and filled into the cavity product portion 9.
[0028]
A hydraulic cylinder 25 is liquid-tightly disposed in the movable mold 2 above the circular gate 10 via a seal packing 27, and a pressurizing stem 14 is attached to the hydraulic cylinder 25 by a hydraulic pressure to form a cavity first hot water reservoir. A pressure stem piston 23 that can be advanced and retracted to and from 11 is accommodated via a seal packing 27, and the pressure stem piston 23 advances and retracts a closing pin 13 that can close the circular gate 10. A closing pin piston 24 that can be operated is accommodated coaxially with the pressurizing stem piston 23. After filling the mold cavity with the molten metal, the closing pin 13 is advanced by the piston 24, the circular gate 10 is closed, and then the pressure stem 14 is advanced by the piston 23, and the cavity product part 9 is not yet filled. The molten metal for the void volume and the solidification shrinkage volume is pressurized and supplied from the cavity first hot water reservoir 11. At that time, since the stalk of the pressure stem 14 is large, a sufficient amount of molten metal can be replenished and pressure-filled.
[0029]
Even during pressurization by the pressurization stem 14, a slight amount of oxide generated on the molten metal surface in the stalk 5, a solidified layer on the surface of the molten metal formed by cooling at the inlet of the circular gate 10, and gas entrainment generated by a jet flow. All the layers gather at the uppermost part of the hot water reservoir 11 by the gate jet 15, remain in the cavity first hot water reservoir 11 without being pushed out by the pressure stem 14, and do not flow into the cavity product portion 9. As a result, there is no casting defect caused by these. Further, on the outer periphery of the pressurizing stem 14, a two-stage gap including a gas discharge gap 18 communicating with the gas discharge hole 29 and a molten metal solidification zone gap 17 is provided. The gas discharge hole 29 is connected to a vacuum device (not shown) for performing vacuum suction during pouring via a pipe having a flow rate control valve (not shown). Furthermore, as shown in FIG. 4d, the solidified layer formed by the molten metal solidification zone gap 17 is taken out together with the product material, so that a vacuum suction passage for the gas is ensured at every casting.
[0030]
Two small cavity second hot water reservoirs 19 are formed above the end of the cavity product portion 9, and a hydraulic cylinder 31 is disposed in the movable mold 2 above the hot water reservoir 19. The hydraulic cylinder 31 accommodates a pressure pin piston 30 that can advance and retract the two pressure pins 20 to and from the cavity second hot water reservoir 19 by hydraulic pressure. The two pressure pins 20 have an axial core parallel to the mold opening / closing direction and perpendicular to the mold parting surface, and are liquid-tightly provided on the movable mold 2 via the seal packing 33. Also on the outer periphery of these pressurizing pins 20, a two-stage gap comprising a gas discharge gap 22 communicating with the gas discharge hole 34 and a molten metal solidification zone gap 21 is provided. The gas discharge hole 34 is also connected to a vacuum device for performing vacuum suction during pouring via a pipe having a flow rate control valve. Then, after replenishment and filling in the cavity product portion 9 by the pressurization stem 14, these pressurizing pins 20 are pushed out to pressurize the molten metal in the cavity product portion 9 through the cavity second hot water reservoir 19. ing. Further, the outer diameter of the pressure pin 20 is configured to be slightly smaller than the diameter of the inlet of the cavity second hot water reservoir 19. Since these pressurizing pins 20 also slide each time, the solidified layer formed by the molten metal solidifying zone gap 21 is pushed out by an extruding pin (not shown) attached to the product material and does not remain in the gas passage hole, but vacuum suction of gas. A passage is secured.
[0031]
Next, the operation will be described. After completion of mold clamping, the inside of the cavity is evacuated through molten metal solidification zone gaps 17, 21, gas discharge gaps 18, 22 and gas discharge holes 29, 34 provided close to the outer periphery of the pressure stem 14 and the pressure pin 20. The pressure is reduced by suction, and the molten metal 16 is sucked up into the cavity first hot water reservoir 11 through the stalk 5. The molten metal 16 moves up the stalk 5, passes through the circular gate 10 of the fixed mold 1, and is ejected (FIG. 3), and then filled into the cavity product portion 9. In general, since there is a flow resistance in the cavity product portion 9, before the molten metal reaches the cavity second hot water reservoir 19 below the pressurizing pin, the cavity first hot water reservoir 11 in the upper part of the circular gate 10. Is filled with the molten metal (FIG. 4a), but when the hot water enters the molten metal solidification zone voids 17 and 21 by vacuum suction through the gas discharge holes 29 and 34, the passage is narrow and the molten metal is melted. On the contrary, since the cooling area is large, the cooling rate is large, the solidification progresses and the fluidity is lowered, and the force due to vacuum suction is not so large. Therefore, the tip of the molten metal is the gap 17 for the molten metal solidification zone. It stops in the middle of the gas and does not solidify and enter the gas discharge gap 18.
[0032]
When the flow of the molten metal in the cavity stops, the flow of the suction gas also stops and the degree of vacuum in the gas discharge passage and the like increases, so this is detected as a signal of completion of filling, and the closing pin 13 is immediately moved forward to form a circle. The gate 10 is inserted and closed (FIG. 4b). After the molten product in the cavity product section 9 and the cavity first hot water storage section 11 is closed so as not to flow backward to the stalk 5 in this way, the pressure stem 14 is immediately advanced to pressurize, and the internal capacity of the cavity first hot water storage section 11 is increased. The cavity product part 9 is replenished and filled with the molten metal in a semi-solid state (FIG. 4c). When the filling is completed and the cooling is started, solidification shrinkage of the molten metal 16 occurs. Therefore, a high pressure is applied to the pressurizing stem 14 to advance and replenishment according to the solidification shrinkage volume is performed. When the circular gate 10 is closed by the closing pin 13, even if the contact between the closing pin 13 and the circular gate 10 is not perfect, the molten metal present in the small gap quickly cools and solidifies, and the molten metal is stalk 5 from the circular gate 10. In addition, the molten metal in the gate 10 and the stalk 5 does not have a pulling force due to the vacuum and falls to the holding furnace.
[0033]
In the case of replenishment filling with the pressurizing stem 14, the resistance is small, the force of the pressurizing cylinder of the pressurizing stem 14 is small, and the hydraulic pressure in the hydraulic cylinder can be advanced. By the replenishment filling by the advancement of the pressurization stem 14, after the molten metal replenishes and fills the cavity product part 9 and the cavity second hot water reservoir part 19 (FIG. 6a), the pressurization pin 20 is advanced (FIG. 6b). . The pressurization by the pressurization pin 20 is started upon detection of this because the flow resistance increases and the hydraulic pressure increases with the completion of the filling by the pressurization stem 14. Replenishment according to the solidification shrinkage volume due to the advancement of the pressurization stem 14 is difficult to transmit pressure to the opposite end of the cavity product part 9, so the pressurization pin 20 around the end is actuated to pressurize the entire surface. As a result, a product with a dense structure free of shrinkage due to coagulation and condensation can be obtained. After the cooling and solidification of the molten metal in the cavity product part 9 is completed, the product material which has been opened by the mold and opened by the movable mold can be pushed out by the pressure pins and the push pins (FIGS. 4d and 6c). ).
[0034]
【The invention's effect】
When the casting apparatus of the present invention is used, the structure of the gas discharge system around the pressurization stem and the pressurization pin is simple, and the occurrence of trouble during operation is reduced. In particular, when the vacuum suction mechanism is used, the molten metal prior to the molten metal flows into the narrow space for the molten metal solidification zone only by the vacuum suction force, so that it solidifies and stops there and does not enter the gas discharge gap passage. Further, the depth of the first hot water reservoir is increased, so that the stalk of the pressurization stem can be lengthened, and a sufficient volume of molten metal for refilling and coagulation shrinkage in the cavity product part can be obtained. Can be pressed to obtain a cast product having a denser structure and strength. Further, by closing the circular gate with a closing pin having a diameter slightly smaller than the inner diameter of the circular gate, the molten metal in the stalk can be quickly returned to the holding furnace and the product can be easily taken out.
[0035]
In addition, when using the casting apparatus of the present invention equipped with a vacuum suction mechanism, when filling molten metal into the mold cavity, a high-pressure injection device is not required for vacuum suction, and the circular gate is closed after filling. The necessary and sufficient pressure can be applied with a small pressure, so it can be handled with a mold clamping force of 1/3 to 1/5 that of the conventional high pressure method. Can be greatly reduced. In addition, since the molten metal is sucked directly from the holding furnace, no oxide is generated, and since the passage is short, there is little generation of a solidified layer, and the cavity first hot water reservoir having an appropriate height at the exit of the circular gate. This prevents the jet from colliding with the ceiling, eliminates gas entrainment, and allows the remaining oxide and solidified layer to stay in the first hot water reservoir, resulting in a dense and free of impurities. It is possible to obtain a cast product having a proper structure. Furthermore, when filling molten metal into the cavity only by vacuum suction, the molten metal holding furnace is not sealed as in low pressure casting, so not only the equipment cost is reduced, but also the hot water surface is raised and stalk is reduced. The arrangement and operation of the device can be facilitated, such as shortening.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view of a vertical casting apparatus of the present invention.
FIG. 2 is a cross-sectional view taken along the line AA of FIG.
FIG. 3 is an explanatory view showing a state of sucking molten metal in the vertical casting apparatus of the present invention.
FIG. 4 is an explanatory view showing an operating state in the vertical casting apparatus of the present invention following FIG. 3;
FIG. 5 is an explanatory view showing a state before the molten metal flows in the operating state of the pressure pin in the vertical casting apparatus of the present invention.
6 is an explanatory view showing an operating state in the vertical casting apparatus of the present invention continued from FIG. 5; FIG.
[Explanation of symbols]
1 Fixed mold
2 Movable mold
3 Fixed platen
4 Movable platen
5 Stoke
6 Molten metal holding furnace
7,16 molten metal
8 Hot water surface
9 Mold cavity
10 round gate
11 Cavity 1st hot water reservoir
12 Side gate
13 Blocking pin
14 Pressure stem
15 Jet
17 Pressure gap for molten metal solidification zone
18 Pressurized stem gas discharge gap
19 Cavity 2nd Bath
20 Pressure pin
21 Pressure gap for molten metal solidification zone
22 Pressure pin outer periphery gas discharge gap
23 Piston for pressure stem
24 Piston for closing pin
25 Hydraulic cylinder
26 Pressure oil inlet a, b, c
27 Pressure Stem Seal Packing
28 Blocking pin Seal packing
29 Pressurization stem discharge passage
30 Pressure pin Piston
31 Pressure pin Hydraulic cylinder
32 Pressure oil inlet
33 Pressure pin Seal packing
34 Pressure pin Gas discharge passage
35 Mold seal packing
36 Pressure stem cooling water hole
37 Pressure pin cooling water hole
38 Stoke seal packing

Claims

A lower fixed mold and an upper movable mold capable of forming a mold cavity having a gas discharge path and a molten metal solidification zone gap communicating with the gas discharge path provided in the vicinity of the gas discharge path ; A casting means for supplying and filling molten metal into the mold cavity from below, and the molten metal cast into the mold cavity by the casting means is provided in the fixed mold after filling the cavity. A vertical casting apparatus comprising a closing means for closing the molten metal inflow gate and a pressurizing means for pressurizing the molten metal in the closed mold cavity ,
The mold cavity includes a cavity product portion and a cavity hot water reservoir portion, the cavity hot water reservoir portion located above the molten metal inflow gate, and the cavity first hot water reservoir of the cavity product portion. A vertical casting apparatus comprising one or two or more cavity second hot water reservoirs located above the vicinity of the end opposite to the first part.

A lower fixed mold and an upper movable mold capable of forming a mold cavity having a gas discharge path and a molten metal solidification zone gap communicating with the gas discharge path provided in the vicinity of the gas discharge path; A casting means for supplying and filling molten metal into the mold cavity from below, and the molten metal cast into the mold cavity by the casting means is provided in the fixed mold after filling the cavity. A vertical casting apparatus comprising: closing means for closing the molten metal inflow gate; and pressurizing means for pressurizing the molten metal in the closed mold cavity,
The closing means for closing the molten metal inflow gate provided in the fixed mold includes a closing pin capable of opening and closing the circular molten metal inflow gate, and the diameter of the insertion portion of the closed pin to the circular molten metal inflow gate is circular. It is configured to be slightly smaller than the inner diameter of the inflow gate, and the inner diameter of the circular molten metal inflow gate is configured to be smaller than the inner diameter of the casting stalk disposed on the lower side of the fixed mold. A vertical casting apparatus.

Pressurizing means for pressurizing the molten metal in the closed mold cavity, ( 1 ) A pressure stem that is slidably disposed in a movable mold above the first hot water reservoir, and / or has a closing pin slidably provided at the center thereof; and / or ( 2 ) 2. A vertical casting apparatus according to claim 1, further comprising one or more pressure pins slidably disposed on a movable mold above the cavity second hot water reservoir.

The pressure stem and the closing pin are disposed in the movable mold above the circular molten metal inflow gate, and the diameter of the inlet of the circular cavities first hot water reservoir formed in the state where they are raised is the diameter of the circular molten metal inflow gate. So that the height of the ceiling of the cavity first hot water reservoir at the ascending limit of the pressurizing stem and the closing pin is 10 mm or more higher than the height of the molten metal jet ejected from the circular molten metal inflow gate. 4. The vertical casting apparatus according to claim 3, wherein the vertical casting apparatus is configured as follows.

The casting means for filling the mold cavities with the molten metal from the lower side sucks the gas in the mold cavities by vacuum suction, and through the casting stalk provided on the lower side of the fixed mold, the lower molten metal holding furnace The vertical casting apparatus according to any one of claims 1 to 4, further comprising a vacuum suction mechanism that vacuum-fills the molten metal.

The vertical casting apparatus according to any one of claims 1 to 5, wherein a gap for the molten metal solidification zone communicating with the gas discharge passage is provided close to the pressurizing means.

A molten metal solidification zone gap communicating with a gas discharge passage provided close to the pressurizing means is formed between the outer peripheral surface of the pressurization stem and / or the pressurization pin and the inner peripheral surface of the movable mold. 7. The vertical casting apparatus according to claim 6, wherein the vertical casting apparatus communicates with the gas discharge hole through a gas discharge gap or a gas discharge groove.

It is provided concentrically with the pressure stem and / or the pressure pin, and is 1-5 than the diameter of the pressure stem and / or the pressure pin. mm 10-40 for large internal diameter mm A melt solidification zone gap and a gas discharge gap having a certain depth are provided concentrically with the pressure stem and / or the pressure pin, and 0.4 to 1. 0 mm 8. The vertical casting apparatus according to claim 7, further comprising a gas discharge gap having a large inner diameter, or a gas discharge groove extending in an axial line on an outer peripheral surface of the pressure stem and / or the pressure pin.

Using the vertical casting apparatus according to any one of claims 1 to 8, from the molten metal holding furnace. After the molten metal is cast into the mold cavity through the talk, the molten metal fills the cavity, then the molten metal inflow gate provided in the fixed mold is closed, and then the molten metal in the mold cavity is pressurized to sink during solidification. A solid casting method characterized by casting a cast product that does not generate a nest and does not entrain gas.