JP3596826B2 - Optical element molding method - Google Patents

Description

なお、この表１には、実施例１および以後に述べる実施例２、３についてのガラス素材の重量、ガラス素材の接触面積、ガラス素材の吸着力の作用面積が具体的な数値で示されている。なお、ガラス素材の接触面積について、その大小は、ガラス素材の、吸着前での変形だけに、その意味があり、吸引力との関係については、あくまで、外圧との気密（全周密着状態）が保持されれば問題ない。
【００４９】
【表２】

上表において、吸着圧力はガラス素材の重量／吸着力の作用面積（吸着口の吸引面積）で設定されることが理解される。また、しわなどの変形を起こさせない範囲での吸着圧力差は、ガラス素材の粘度との関係で制限される。換言すれば、ガラス素材の種類には関係なく、あくまでも、ガラス粘度と吸着圧力差により、上記の変形が関連する。
【００５０】
この点を考慮して、吸着フィンガーの吸着口の吸引面積、吸着圧力を選択設定しなければならない（これは、以下の実施例においても考慮されるべき事柄である）。
【００５１】
このような本発明の実施例において、溶融坩堝で溶融し、流出した光学ガラスから、受け型上で、高温軟化状態のガラスゴブ（塊）を得て、吸着搬送装置の吸着部の吸着面で接触し、変形させた状態で、吸着・搬送し、プレス成形型を用いて、光学素子を得る場合においては、下記のような特有の効果がある。
【００５２】
・低粘度の（温度が高く、形状が一定しない）ガラスゴブを、プレス成形型に確実、かつ、短時間で搬送でき、成形サイクルを短縮することにより、生産コストを低減できる。
【００５３】
・溶融光学ガラスからプレス成形で光学素子を一貫生産することが可能となり、材料代、成形サイクルの短縮（溶融からプレス成形までの熱エネルギーロスがない）により、生産コストを低減できる。
【００５４】
・ガラスゴブの吸着による変形、および、プレス成形時、折れ込み不良を防止することにより、成形品の歩留りが向上する。
〔実施例２〕
実施例１で用いたのと同じガラス原料を用いて、図３に示すように、有効径が１３ｍｍ、製品外径が約１７ｍｍ、中心肉厚が３ｍｍ、光学面の曲率半径が２０ｍｍ、３０ｍｍの凹メニスカス形状のレンズを成形する成形方法を、図１、図５を参照して具体的に説明する。
【００５５】
実施例１と同様に、ガラス粘度で１０^２ ｄＰａ・ｓに相当する温度を持つ溶融ガラスを流出口２２から受け型１（カーボン系の材質で作られ、球Ｒ３０ｍｍの凹形状）の上に流出させるが、ここでは、ゲート弁１８、１９を閉じた後、成形室１１と取り出し室１２との内部を一旦、真空にした後、非酸化性のガスとしてＮ_２ ガス導入し、上下加熱ヒーター５４、５５に通電し、上下型部材２、３を、ガラス粘度で１０^８．５ ｄＰａ・ｓに相当する温度に加熱しておく。
【００５６】
また、前述の受け型１は、実施例１と同様に、ガラス粘度で１０^８．５ ｄＰａ・ｓに相当する温度に加熱されている。そして、この受け型１で流出ガラスを受け、所定の量の溶融ガラス塊２４を取り、置換室１０に入れ、置換室の蓋１４を閉じ、置換室１０内をＮ_２ ガス置換させた後、ゲート弁１８を開け、ガラス塊２４の上に吸着フィンガー３４を移動した。そして、シャフト３６を上昇駆動させ、受け型１上のガラス２４の上表面２４ａを、図５に示すように、吸着フィンガー３４に接触させた。
【００５７】
ここでは、吸着フィンガー３４が、ガラス塊の上表面２４ａに接触する吸着面３４ａを中央に、また、その周囲にリング状で、吸引力を作用する領域を中心径１１ｍｍ〜１３ｍｍの範囲に形成した吸着口３４ｂを、更に、吸着口３４ｂの外周にリング状の吸着面３４ｃを具備している。
【００５８】
而して、この時、シャフト３６に設置した圧力センサー３６ａにより、吸着フィンガー３４にて、圧力１５Ｎとなるまで、ガラス上表面２４ａを加圧変形させ、吸着面３４ａ、３４ｃに、全面的に密着させた。この加圧変形に要した時間は５秒であった。
【００５９】
次いで、吸着フィンガーの吸着口に、その内部圧力が、吸着口の外部の圧力より５．００×１０^３ Ｐａ低い圧力の差をつけて、吸引力を作用させ、ガラス２４を吸着保持させ、シヤフト３６を下方に逃がした。更に、シリンダー３２を動かし、吸着されたガラス２４を下型部材３上に置いた。この吸着搬送の終了時（下型部材３上にガラス２４が載置された直後）のガラス粘度は、１０^７ ｄＰａ・ｓであった。
【００６０】
而して、シャフト３３を戻し、ゲート弁１８を閉じ、上下型部材２、３をガラス粘度で１０^８．５ ｄＰａ・ｓに相当する温度に保持した状態で、シリンダー３７を駆動し、シャフト３８を介して、上型部材２に圧力（４５００Ｎ）を、上型部材２のフランジの下面が胴型４の上面に完全につき当たる迄の８０秒間、加えて、ガラスをプレス成形する。
【００６１】
この状態で、ガラス２４ｂを冷却し、これが冷却されて収縮するのに合わせ、下型部材３を追従させるため、下型シリンダー３９を作動させて、下型シャフト４０の先端で、下型部材３を下から２５００Ｎの力で押圧した。
【００６２】
ガラス２４ｂがそのガラス粘度で１０^１４ｄＰａ・ｓに相当する温度になった時、下型シリンダー３９による加圧をやめ、その後、直ちに上型シリンダー３７を上方に動かし、上型シャフト３８に固定されているフック６で、上型部材２のフランジを引っかけて、成形型を開いた。
【００６３】
次いで、実施例１と同様の方法で、ガラス製品２４ｂを取り出し室１２の外に取り出した。この場合、溶融ガラスを受け型１で受け止めてから、ガラス製品を取り出すまでの成形タクトは、２１０秒であった。
【００６４】
この成形動作を、実施例１と同様に連続的に繰り返し、得られた製品２４ｂの品質を確認したところ、製品２４ｂの外観には、ガラスゴブの吸着、搬送時における変形、シワなどの異常も何ら認められず、また、面精度もアス、クセとも一本以内の良好なものが得られた。また、１００回の連続使用の時点での各型部材１、２、３および吸着フィンガー３４の表面を観察したところでは、有害な揮発物の付着は認められず、まだ、十分に成形を継続できる状態であった。
【００６５】
また、本実施例においては、ガラス製品形状が凹メニスカスレンズであったが、同製品形状が、凸メニスカスレンズおよび、両凹レンズについても、上述の成形方法において、同様の成形を行ったところ、同等の成形についての結果を得ることができた。
【００６６】
なお、本実施例では、高温軟化状態のガラスゴブ（塊）を、吸着搬送装置の吸着部の吸着面で、成形品に近似した形状に変形させた後に、プレス成形型を用いて成形し、光学素子を得るようにしたので、その点で、下記のような特有の効果が得られた。
【００６７】
・プレス成形品の形状領域の拡大が図れる。
【００６８】
・低粘度の（温度が高く、形状が一定しない）ガラスゴブを、プレス成形型に確実かつ、短時間で搬送でき、成形サイクルを短縮することにより生産コストを安価にできる。
【００６９】
・溶融光学ガラスから成形光学素子を一貫生産することが可能となり、材料代、成形サイクルの短縮（溶融からプレス成形まで熱エネルギーロスがない）により生産コストを安価にできる。
〔実施例３〕
図７では、本発明の第３の実施例を説明するための、装置の断面を概略的に示している。ここで、符号７１はガラス塊、７６はガラス塊の置き台、７４はガラス塊７１を大気雰囲気から非酸化性雰囲気へ置換するために、成形室１１に隣接して設置された置換室である。置換室７４は、置換室チャンバー７４ａと大気との連絡をする開閉口７５からなっていて、チャンバー７４ａには、搬入シリンダー７３が取り付けらけており、シリンダー７３は、そのシリンダーシャフト７２をシールゴム８１を介して置換室７４に挿入させている。シャフト７２の先端には、吸着フィンガー７２ａが取り付けらており、それによって、置換室７４に置かれたガラス塊７１を吸着し、ゲート弁１８を通過して、成形室１１の内部に設けられている加熱型７０の上に移動できるようになっている。また、置換室チャンバー７４ａには、図示されていない真空引き用の排気口と雰囲気ガス供給用の供給口が設けらている。
【００７０】
成形室１１は、成形室チャンバー１５により、外気と遮断されていて、ゲート弁１８、１９で仕切られた置換室７４および取り出し室１２に隣接している。チャンバー１５には、加熱型の駆動シリンダー８３と、搬送シリンダー８５と、上下において、精密成形用の上型シリンダー３７と下型シリンダー３９とが取り付けられており、シリンダー８３、８５、３７、３９の各シリンダーシャフト８２、７８、３８、４０は、シールゴム８４、８６、６４、６５を介して、成形室１１に挿入されている。
【００７１】
シリンダーシャフト８２の先端には、ヒーター７０ａを内蔵した加熱型７０が取り付けられており、シリンダー８３を上昇駆動させることにより、吸着フィンガー７２ａにより吸着されたガラス塊７１を、加熱型７０の上に載置できるようになっている。また、シリンダーシャフト８２の中間部には圧力センサー８２ａが取付けられている。
【００７２】
符号７７は、成形室１１内に搬送されたガラス塊７１を、プレス成形可能な温度まで加熱するための加熱装置である。シリンダーシャフト７８の先端には、ヒーター８０を内蔵した吸着フィンガー７９が取り付けられており、それによって加熱型７０の上でプレス成形可能な温度まで加熱されたガラス塊７１を吸着し、下型部材３の上に載置できるようになっている。
【００７３】
また、シリンダーシャフト３８の先端には、上型部材２を上昇動作して、成形型を開放するためのフック６が取り付けられている。シャフト３８、４０の間には胴型４が置かれており、胴型４には、その上下間を貫通して開けられた貫通穴に、成形型の上型部材２と下型部材３が挿入されていて、上型部材２は、加圧時には、シャフト３８の先端により加圧され、上昇時には、上部に設けられているフランジ部をフック６で引っかけて、引き上げる構造になっている。また、下型部材３は、底板５で支えられていて、胴型４の内部において上下に動かせる構造となっている。更に、胴型４には、上型部材２および下型部材３の温度調整用に上型ヒーター５４と下型ヒーター５５が設けられている。
【００７４】
取り出し室１２は、成形室１１と同様に、取り出し室チャンバー１６とその蓋１７から構成されていて、チャンバー１６には、置き台の駆動シリンダー４１と取り出しシリンダー４４とが取り付けられている。両シリンダー４１と４４のシリンダーシャフト４２、４５の一端側は、シールゴム６７、６８を介して、成形室１１の内部に挿入されていて、シャフト４２の先端には、置き台４３が取り付けられている。シャフト４５の先端には、吸着フィンガー４６が取り付けられていて、シリンダー４４を駆動することによって、下型部材３上の成形品を置き台４３の上に載置できるようになっている。
【００７５】
また、蓋１７とチャンバー１６との間にはシールゴム６６が取り付けられていて、気密を保てるようになっている。成形用チャンバー１５と取り出し室チャンバー１６には、置換室チャンバー１３の場合と同様に、図示されていない真空引き用の排気口と雰囲気ガス供給用の供給口が設けられている。
【００７６】
このような構成の光学素子成形装置を用いて、本発明の成形方法を具体的に説明する。まず、ガラス塊７１を成形素材（ブランク）を準備する。ガラス塊７１としては、溶融ガラス流をシャーマークを発生させることなく得た、外観上に欠陥の無いガラス塊が、コスト上もっとも望ましいが、光学素子の生産が、小ロットで行われる場合、その成形素材には、予め、研削・研磨した加工品が用いられても良い。本実施例においては、実施例１と同じガラス材で、成形レンズ形状に近似させた研削・研磨加工品を用い、図２に示すように、有効径が１２ｍｍ、製品外径が約１６ｍｍ、中心肉厚が４ｍｍ、光学面の曲率半径が２５ｍｍ、３０ｍｍの両凸形状レンズを成形する場合を、図７を参照して下記に説明する。
【００７７】
常温で、ガラス塊７１を、置換室７４に隣接する位置に準備する。置換室７４の開閉口７５を開け、置換室７４内部を大気雰囲気にする。常温のガラス塊７１を供給搬送装置（図示せず）を用いて、置換室７４内のガラス置き台７６へ載置する。吸着搬送装置（図示せず）は置換室７４の外部へ退出し、開閉口７５は閉じられ、置換室７４は気密に保たれる。
【００７８】
置換室７４内部を非酸化性ガス雰囲気へ置換後（置換室７４内の酸素濃度と成形室１１内の酸素濃度は同等）、ゲート弁１８を開ける。搬入シリンダ７３を駆動させ、シャフト７２の吸着フインガー７２ａをガラス塊７１の上に移動し、ガラス塊の上表面７１ａを吸着フィンガー７２ａにて吸着する。更に、シリンダー７３を動かし、吸着されたガラス塊７１を成形室１１内の加熱型７０上に置き、シャフト７２を戻し、ゲート弁１８を閉める。
【００７９】
加熱型７０上に置かれた常温のガラス塊７１は、加熱型７０の上方に設置された加熱装置７７によって、プレス可能な温度まで加熱される。加熱装置７７は、ハロゲンランプの周囲に、回転楕円体形状の反射鏡を有する構造をしており、ハロゲンランプから発光された赤外光を、ガラス塊７１へ集光することができる。
【００８０】
本実施例においては、加熱型７０は、カーボン系の材質で作られており、内蔵するヒーター７０ａにより、常時、ガラス粘度にて１０^８．５ ｄＰａ・ｓに相当する温度に加熱保持されている。この加熱型７０上に置かれた常温のガラス塊７１は、加熱装置７７のハロゲンランプの出力１００Ｗにて、加熱開始より４０秒後に、ガラス粘度にて１０^７．９ ｄＰａ・ｓに相当する温度まで加熱された。
【００８１】
次いで、搬入シリンダー８５を回転駆動させ、シャフト７８の吸着フィンガー７９を、加熱されたガラス塊７１の上に移動した。シャフト８２を上昇駆動させ、加熱型７０上のガラス塊７１の上表面７１ａを、吸着フィンガー７９の吸着口７９ａに接触させ、加圧を行った。この時、シャフト８２に設置した圧力センサー８２ａにより、圧力８Ｎとなるまで、ガラス上表面７１ａを加圧変形させた。この加圧変形に要した時間は３秒であった。
【００８２】
次いで、吸着フィンガー７９には、その吸着口の内部圧力を、吸着口の外部圧力より１．００×１０^４ Ｐａ低い圧力差をつけた状態にして、ガラス７１を吸着、保持させ、シャフト８２を下方に逃がした（この時の吸着保持可能な圧力差の範囲は、５．００×１０^３ Ｐａ〜２．００×１０^４ Ｐａで設定される）。
【００８３】
更に、搬入シリンダー８５を回転駆動させ、吸着されたガラス塊７１を下型部材３上に置いた。この吸着、搬送の終了時、即ち、下型部材３上にガラス塊７１が載置された直後のガラス粘度は、１０^８．２ ｄＰａ・ｓであった。
【００８４】
シャフト７８を戻した後は、実施例１と同様の方法で、ガラス製品７１ｂをプレス成形し、型開きし、その後、取り出し室１２の外に取り出した。この時の成形条件は、下記の通りであった。
【００８５】
・上型部材２の加圧力：４８００Ｎ、プレス変形時間：７０秒
・下型部材３の加圧力：２８００Ｎ（この際、ガラス７１ｂが、その粘度にて１０^１４ｄＰａ・ｓに相当する温度である）
・溶融ガラスを受け型で受け止めてから、成型品を取り出すまでの成形タクト：２７０秒
この成形動作を、実施例１と同様に、連続的に繰り返し、得られた製品２４ｂの品質を確認したところ、製品７１ｂの外観には、ガラスゴブの吸着搬送時による変形、シワなどの異常が何も認められず、また面精度もアス、クセとも一本以内の良好なものが得られた。また、１００回の連続使用の時点で、各型部材１、２、３および吸着フィンガー７９の吸着面の表面観察では、有害な揮発物の付着が認められず、まだ、充分に連続成形できる状態であった。
【００８６】
また、本実施例において、常時、ガラス粘度にて１０^８．５ ｄＰａ・ｓに相当する温度に加熱、保持された加熱型７０上におかれた常温のガラス塊７１は、加熱装置７７のハロゲンランプの出力１００Ｗにて、加熱開始より３０秒後に、ガラス粘度にて１０^８．２ ｄＰａ・ｓに相当する温度まで加熱された。
【００８７】
次いで、搬入シリンダー８５を回転駆動させ、シャフト７８の吸着フィンガー９を、加熱されたガラス塊７１の上に移動した。シャフト８２を上昇駆動させ、加熱型７０上にあるガラス塊７１の上表面７１ａを、吸着フィンガー７９の吸着口７９ａに接触させ、加圧を行った。この時、シャフト８２に設置した圧力センサー８２ａにより、圧力１０Ｎとなるまで、ガラス上表面７１ａを加圧変形させた。この加圧変形に要した時間は５秒であった。
【００８８】
次いで、吸着フィンガー７９による吸着口の内部圧力を、吸着口の外部圧力より４．００×１０^４ Ｐａ低い圧力差をつけた状態にして、ガラス７１を吸着、保持させ、シャフト８２を下方に逃がした（この時の吸着保持可能な圧力差の範囲は、１．００×１０^４ Ｐａ〜５．００×１０^４ Ｐａの設定されている）。
【００８９】
更に、搬入シリンダー８５を回転駆動させ、吸着されたガラス塊７１を成形下型３上に置いた。この吸着、搬送の終了時、即ち、下型部材３上にガラス塊７１が載置された直後のガラス粘度は、１０^８．５ ｄＰａ・ｓであった。
【００９０】
本実施例では、所定量の光学ガラス塊を、加熱装置を用いて、加熱軟化させ、これで得た高温軟化状態のガラス塊を、搬送部の吸着面で接触し、変形させた状態で吸着、搬送し、プレス成形型を用いて光学素子を得るが、この際に、下記の特有の効果がある。
【００９１】
・高温軟化状態のガラスゴブ（塊）を、プレス成形型に、確実、かつ、短時間で搬送でき、成形サイクルを短縮することにより、生産コストを安価にできる。
【００９２】
・プレス成形型上での軟化のための再加熱時間が不要で、成形サイクルを短縮することにより、生産コストを安価にできる。
【００９３】
【発明の効果】
本発明は、以上説明したように、高温軟化状態のガラス塊を吸着搬送装置の吸着部に吸着し、上下一対の型部材からなる成形型へ搬送し、型部材間にガラス塊を装填して、プレス成形する、光学素子の成形方法において、形状が一定しない高温軟化状態のガラス塊を、前記吸着部の吸着面に接触し、変形させて、前記吸着面に対応した一定形状を前記ガラス塊に形成すると共に、吸着力の作用するガラス塊の表面が変形しない程度の吸引力で、前記ガラス塊を吸着部に吸着し、成形型へ搬送することを特徴とする。
【００９４】
この場合、前記高温軟化状態のガラス塊は、溶融坩堝内部で溶融した光学ガラスをノズルから流出し、受け型に受けて、得られた所定量の高温軟化状態のガラス塊であるか、あるいは、前記高温軟化状態のガラス塊は、受け型に受けた所定量の光学ガラス塊を、加熱装置を用いて加熱軟化させて、得られた高温軟化状態のガラス塊であることが望ましい。
【００９５】
また、本発明では、前記高温軟化状態のガラス塊は、吸着を開始する時点で、その粘度が１０^５ ｄｐａ・ｓ以上１０^８ ｄｐａ・ｓ以下であり、かつ、前記吸着部の吸着力は、外部との圧力差が１．００×１０^２ Ｐａ以上５．００×１０^４ Ｐａ以下の範囲であり、前記吸着面は、その際のガラス塊の重量に見合う面積を保持していることを特徴とする。
【００９６】
この場合、前記吸着搬送装置による搬送に伴う吸着が終了する時点で、前記ガラス塊の粘度が１０^６ 〜１０^９ ｄｐａ・ｓの範囲にあることが望ましい。更に、前記吸着面は、高温軟化状態のガラス塊を、成形時の成形品に近似する形状に変形させるのに適応した形状であるとよい。
【００９７】
これにより、本発明においては、ガラスゴブを第１のガラスゴブ受け型から第２のプレス成形型へガラスゴブを搬送し、プレス成形を行う際に、未だ高温軟化状態のガラス塊を、その低粘度（温度が高く、形状が一定しない）のまま、確実に吸着し、第２のプレス成形型へ短時間で搬送供給することにより、成形可能な粘度状態で、ガラスゴブを成形型に装填でき、高精度、高効率生産を実現できるという優れた効果が得られる。
【図面の簡単な説明】
【図１】本発明の第１、第２の実施例に係る光学素子の成形方法において用いる成形装置の構成を示す概略断面図である。
【図２】本発明の第１、第３の実施例に係る光学素子の成形方法において成形される精密ガラス製品の一例を示す断面図である。
【図３】本発明の第２の実施例に係る光学素子の成形方法において形成される精密ガラス製品の一例を示す断面図である。
【図４】本発明の第１の実施例に係る光学素子の成形方法における高温軟化状態のガラス塊を吸着している状態の一例を示す断面図である。
【図５】本発明の第２の実施例に係る光学素子の成形方法における高温軟化状態のガラス塊を吸着している状態の一例を示す断面図である。
【図６】本発明の第１の実施例に係る光学素子の成形方法において、成形工程の一部を示す工程説明図である。
【図７】本発明の第３の実施例に係る光学素子の成形方法において用いる成形装置の構成を示す概略断面図である。
【符号の説明】
１ 受け型
２ 上型部材
３ 下型部材
４ 胴型
５ 底板
６ フック
１０，７４ 置換室
１１ 成形室
１２ 取り出し室
１３，７４ａ 置換室チャンバー
１４ 置換室蓋
１５ 成形室チャンバー
１６ 取り出し室チャンバー
１７ 取り出し室蓋
１８，１９ ゲート弁
２０ 溶融炉
２１ 流出パイプ
２２ 流出口
２３ 溶融ガラス
２４，７１ 溶融ガラス塊
２４ａ 溶融ガラス塊上表面
２４ｂ 精密ガラス製品
３２ 搬入シリンダー
３３ 搬入シリンダーシャフト
３４，７９ 吸着フィンガー
３４ａ 吸着フィンガー吸着面
３４ｂ，ｃ 吸着フィンガー吸着口
３５ 受け型駆動シリンダー
３６ 受け型駆動シリンダーシャフト
３６ａ 受け型圧力センサー
３７ 上型シリンダー
３８ 上型シリンダーシャフト
３９ 下型シリンダー
４０ 下型シリンダーシャフト
４１ 置台駆動シリンダー
４２ 置台駆動シリンダーシャフト
４３ 置台
４４ 取出しシリンダー
４５ 取出しシリンダーシャフト
４６ 吸着フィンガー
５１ 受け型ヒーター
５２，８０ 吸着フィンガーヒーター
５３ 置換室ヒーター
５４ 上型ヒーター
５５ 下型ヒーター
６１〜６８，８１，８４，８６ シールゴム
７０ 加熱型
７２ 搬入シリンダーシャフト
７３ 搬入シリンダー
７５ 開閉口
７６ ガラス載置台
７７ 加熱装置
７８ 吸着フィンガーシャフト
８５ 吸着フィンガーシリンダー[0001]
[Industrial applications]
The present invention mainly relates to a method for molding an optical element, in which a high-precision optical glass element such as a lens or a prism is directly press-molded from glass in a high-temperature softened state.
[0002]
[Prior art]
Conventionally, in order to obtain a glass lens, a processing method of grinding and polishing a glass block having a predetermined size into a predetermined shape has been adopted. However, the production of a lens having an aspherical shape requires a very high-precision processing technique, and also requires a large amount of processing time for both of the above-mentioned grinding and polishing, resulting in a large cost.
[0003]
Therefore, in recent years, a molding method has been proposed in which a preformed glass material that has been softened by heating is directly pressed in a non-oxidizing atmosphere using a mold having an aspherical shape. Aspherical lenses can now be obtained.
[0004]
Further, in this press molding method, in order to obtain an inexpensive press molded product, the molten glass is directly received in a receiving mold, and the glass mass (cob) in a high-temperature softened state is transferred to a molding die having an aspherical shape and loaded. Then, a molding method for obtaining an aspherical lens by press working has also been proposed. As the molding method, for example, those described in JP-A-3-60435 and JP-A-5-238761 are disclosed. Are known.
[0005]
That is, in the former, a glass gob is placed on a first heat processing jig (glass cob receiving die), and a second heat processing jig (press forming die) is brought into contact with the upper surface thereof from above. By inverting the glass gob, the glass gob is transferred to the second heat processing jig, and the glass gob is press-formed.
[0006]
In the latter method, the glass gob is engaged with a holding member, and the holding member is moved from the first glass gob receiving die to the second press forming die using a conveying means, so that the glass gob is conveyed and loaded. And press forming.
[0007]
[Problems to be solved by the invention]
However, the above-described conventional example has the following problems in transporting the softened glass gob from the first glass gob receiving mold to the second press mold and press-molding the same. That is, there is a concern about the reliability of conveyance due to the variation in the degree of contact between the mold and the glass gob during the reversing operation. descend. Therefore, in order to improve mass productivity, a large number of gob receiving dies and press dies are required.
[0008]
In addition, in order to accurately position the holding member and the gob receiving die and the press forming die in a hot state, a considerably complicated device and mechanism must be used. Further, at the time of pressing, burrs are generated in the gap between the holding member and the press mold, or, between the holding member and the molded product, glass powder is generated at the time of mold release, in order to eliminate this, Since the operation needs to be interrupted, there is a problem in mass production moldability.
[0009]
Further, when the glass gob is transported using the holding member, the glass gob must be cooled and solidified to a viscosity state that does not cause the holding member to fall off from the locking portion or to be displaced due to its own weight deformation. For this reason, it is necessary to reheat the glass to a state in which the glass can be molded on the press mold again. Therefore, the cycle time becomes longer, and the mass productivity decreases.
[0010]
Further, as described above, in the step of reheating to a glass viscous state that can be formed by the press preheating step, the upper surface shape of the glass gob has a free surface shape due to surface tension and self-weight deformation. When performing precision molding of a convex R-shaped surface that is smaller than the R shape of the upper surface of the glass gob with a concave press mold, a defect phenomenon that gas remains near the center of the glass gob that contacts the mold during press molding. Is more likely to occur. Conversely, when the free surface shape (having a gentle convex R shape) of the glass bump is press-formed with a convex press mold to perform precision molding of the concave surface, the convex surface mold is used. The transfer of the contact surface between the outer peripheral portion and the deformed glass tends to cause a defective phenomenon (the deformation pressure is released in the direction of the outer peripheral edge portion when the glass is deformed), which also leads to a decrease in mass productivity.
[0011]
[Object of the invention]
The present invention has been made to solve the above problems, and a first object of the present invention is to transfer a glass gob from a first glass gob receiving die to a second press forming die to perform press forming. When performing, the glass lump still in a high-temperature softened state is reliably adsorbed while maintaining its low viscosity (high temperature and irregular shape), and is conveyed and supplied to the second press mold in a short time. It is an object of the present invention to provide a method for molding an optical element, which can load a glass gob into a mold in a moldable viscosity state and enables high-precision and high-efficiency production.
[0012]
Also, a second object of the present invention is to receive a molten glass melted in a melting crucible in a first receiving mold and to adsorb the molten glass in a high-temperature softened state in order to obtain an inexpensive press-formed product. An object of the present invention is to provide a method for molding an optical element, which is capable of shortening a molding tact and enabling high-efficiency production by supplying a molding device with a conveying device, and particularly suitable for a large lot.
[0013]
Further, a third object of the present invention is to heat and soften a glass lump by using a heating device on a first mold in order to obtain an inexpensive press-formed product, thereby obtaining a high-temperature softened state. By obtaining a glass gob and supplying it to a molding die by means of a suction conveyance device, it is possible to shorten the molding tact and enable high-efficiency production. To provide.
[0014]
A fourth object of the present invention is to supply a glass gob in a high-temperature softened state from a receiving mold to a molding die in a state where defects such as wrinkles do not occur at the time of press molding by required suction conveyance. Another object of the present invention is to provide a method for molding an optical element, which shortens the molding tact and enables high-efficiency production.
[0015]
In this case, in order to transfer a low-viscosity (high-temperature) glass gob to a molding die while maintaining a moldable viscosity state, the suction transfer device sucks the glass gob with a weak suction pressure to reduce the deformation amount. It is necessary. It is preferable that the glass gob be formed into a shape similar to a molded product during the suction and transfer.
[0016]
[Means for solving the problem]
In order to achieve the above object, in the present invention, a glass lump in a high-temperature softened state is adsorbed to a suction section of a suction / transportation device, and is conveyed to a molding die including a pair of upper and lower mold members, and the glass lump is charged between the mold members. In the method of molding an optical element, press molding is performed.In this method, a glass lump in a high-temperature softened state having an irregular shape is brought into contact with the suction surface of the suction portion and deformed, and the glass having a predetermined shape corresponding to the suction surface is deformed. The method is characterized in that the glass block is sucked by the suction unit with a suction force that does not deform the surface of the glass block on which the suction force acts while being formed into a block, and is conveyed to a molding die.
[0017]
In this case, the glass mass in the high-temperature softened state flows out of the optical glass melted in the melting crucible from the nozzle and is received in a receiving mold, and is a predetermined amount of the obtained glass mass in the high-temperature softened state, or It is preferable that the glass lump in the high temperature softened state is a glass lump in a high temperature softened state obtained by heating and softening a predetermined amount of optical glass lump received in a receiving mold using a heating device.
[0018]
In the present invention, the viscosity of the glass lump in the high-temperature softened state is 10 when the adsorption starts. ⁵ dpa · s or more 10 ⁸ dpa · s or less, and the adsorbing force of the adsorbing section is such that the pressure difference from the outside is 1.00 × 10 ² Pa or more 5.00 × 10 ⁴ Pa or less, and the adsorption surface has an area corresponding to the weight of the glass block at that time.
[0019]
In this case, at the time when the suction accompanying the transfer by the suction transfer device ends, the viscosity of the glass lump becomes 10%. ⁶ -10 ⁹ It is desirable to be in the range of dpa · s. Further, it is preferable that the suction surface has a shape adapted to deform a glass lump in a high-temperature softened state into a shape similar to a molded product at the time of molding.
[0020]
【Example】
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1 is a diagram showing an example of an apparatus used to carry out the present invention. Here, reference numeral 20 denotes a melting furnace for melting the glass, and reference numeral 21 denotes an outflow pipe through which the melted glass flows. A heater (not shown) is disposed around the melting furnace 20 and the outflow pipe 21 so that the glass can be melted.
[0021]
Reference numeral 23 denotes glass in a molten state, and reference numeral 22 denotes an outlet provided at the tip of the outflow pipe 21. Below the outlet 22, a molding machine having a replacement chamber 10, a molding chamber 11, and a removal chamber 12 separated from each other by gate valves 18 and 19 is arranged. Is located directly above the receiving mold 1 installed in the receiving mold 1.
[0022]
The replacement chamber 10 includes a replacement chamber 13 and a replacement chamber lid 14. The carry-in cylinder 32 and the receiving drive cylinder 35 are attached to the chamber 13, and the cylinder shaft 33 of each cylinder 32, 35 is provided. , 36 are inserted into the replacement chamber 10 via seal rubbers 62, 63, respectively. A receiving mold 1 having a built-in heater 51 is attached to the tip of the cylinder shaft 36, and receives the molten glass flowing out of the outlet 22 by driving the cylinder 35 upward, as shown in FIG. A glass block 24 can be formed on the mold 1. By driving the cylinder 35 to descend, the receiving mold 1 and the glass block 24 formed thereon can be drawn into the replacement chamber 10.
[0023]
A pressure sensor 36a is attached to an intermediate portion of the cylinder shaft 36, and a suction finger 34 with a built-in heater 52 is attached to the tip of the cylinder shaft 33, as described above. The glass block 24 taken into the replacement chamber 10 is adsorbed, conveyed from the replacement chamber 10 through the gate valve 18 to the molding chamber 11, and the lower mold of the molding die provided inside the molding chamber 11. It can be placed on the member 3.
[0024]
After the receiving mold 1 is drawn into the substitution chamber 10, the lid 14 of the substitution chamber is rotated in the direction of arrow A to cover the substitution chamber chamber 13 via the sealing rubber 61 via the sealing rubber 61. Airtightness can be maintained. Further, the replacement chamber 10 is provided with a heater 53 for controlling the internal temperature, so that an arbitrary ambient temperature can be obtained. Further, the chamber 13 is provided with an exhaust port for vacuuming and a supply port for supplying atmospheric gas (not shown).
[0025]
The molding chamber 11 is isolated from the outside air by the molding chamber 15, and upper and lower mold cylinders 37 and 39 for precision molding are mounted above and below the chamber 15. , 40 are inserted into the molding chamber 11 via sealing rubbers 64, 65, and a hook 6 for opening and closing the upper mold member 2 of the molding die is attached to the tip of the shaft 38. I have.
[0026]
The body mold 4 is placed between the shafts 38 and 40, and the upper mold member 2 and the lower mold member 3 of the molding mold are inserted into the through holes formed through the space between the upper and lower sides of the body mold 4. The upper mold member 2 is pressurized by the tip of the shaft 38 when pressurized, and has a structure in which the flange provided on the upper mold member 2 is pulled up by the hook 6 when ascending. ing. The lower mold member 3 is supported by the bottom plate 5 and has a structure that can be moved up and down inside the body mold 4. Further, the body die 4 is provided with an upper heater 54 and a lower heater 55 for adjusting the temperature of the upper die member 2 and the lower die member 3.
[0027]
The take-out chamber 12 is composed of a take-out chamber 16 and a take-out chamber lid 17, as in the case of the molding chamber 11, and the placing table drive cylinder 41 and the take-out cylinder 44 are attached to the chamber 16. . One end of each of the cylinder shafts 42 and 45 of the cylinders 41 and 44 is inserted into the interior of the molding chamber 11 via seal rubbers 67 and 68. Is attached. Further, a suction finger 46 is attached to the tip of the shaft 45, and the molded product on the lower mold member 3 can be placed on the table 43 by driving the cylinder 44. Further, a seal rubber 66 is attached between the lid 17 and the chamber 16, so that airtightness can be maintained between the two. Further, the molding chamber 15 and the take-out chamber 16 are provided with a vacuum exhaust port and a supply port for supplying atmospheric gas (not shown) as in the case of the replacement chamber 13.
[0028]
Next, an embodiment in which the molding method of the present invention is performed using such an apparatus will be described in detail below.
[Example 1]
In the first embodiment of the present invention, an effective diameter of 12 mm, a product outer diameter of about 16 mm, a center thickness of 4 mm, and a radius of curvature of the optical surface of 25 mm are used as shown in FIG. When molding a biconvex lens with a thickness of 30 mm, the viscosity is 10 when the temperature is 1040 ° C. ² dpa · s, viscosity at 580 ° C is 10 ^8.2 dPa · s, viscosity at 515 ° C is 10 ¹¹ dPa · s, viscosity at 465 ° C is 10 ¹⁴ A glass raw material having the viscosity characteristic is used so that dPa · s is obtained.
[0029]
First, the above-mentioned glass raw material is put into a melting furnace 20, and after vitrification, defoaming and stirring are performed to produce a homogeneous molten glass 23, guided to an outflow pipe 21, and an outlet 22 having a glass viscosity of 10%. ² The temperature was adjusted to dPa · s, and the glass was discharged from the outlet 22.
[0030]
After the gate valves 18 and 19 are closed, the interior of the molding chamber 11 and the take-out chamber 12 is once evacuated, and then N2 is used as a non-oxidizing gas. ₂ The gas is introduced, and the upper and lower heaters 54 and 55 in the body mold 4 are energized, so that the upper and lower mold members 2 and 3 ^8.5 Heated to a temperature corresponding to dPa · s.
[0031]
The receiving surface of the receiving mold 1 made of carbon-based material and having a concave shape of a sphere R: 30 mm, and the suction finger 34 were heated to a glass viscosity of 10 by using heaters 51 and 52, respectively. ^8.5 Heating was performed to a temperature corresponding to dPa · s, the lid 14 of the replacement chamber was opened, the cylinder 35 was driven, and the receiving mold 1 was moved to just below the outlet 22.
[0032]
Then, as shown in FIG. 6A, at the stage where the outflow glass is received by the receiving mold 1 and a predetermined amount of the molten glass block 24 is received, the receiving mold drive shaft 36 is lowered, and the lid 14 of the replacement chamber is closed. Closed.
[0033]
Next, the surface of the glass is 10 ⁵ When the viscosity reaches dPa · s or more, vacuum is applied for 10 seconds, and then the non-oxidizing gas (N ₂ Gas) was introduced for 5 seconds. At this point, the oxygen concentration in the replacement chamber 10 becomes equal to the oxygen concentration in the molding chamber 11, and the surface of the glass ^6.2 The viscosity was dPa · s.
[0034]
Next, the gate valve 18 was opened, the carry-in cylinder 32 was driven, and the suction finger 34 of the shaft 33 was moved onto the glass 24. Further, the shaft 36 is driven upward to bring the upper surface 24a of the glass 24 on the receiving die 1 into contact with the ring-shaped (inner conical surface) suction port surface 34a of the suction finger 34 as shown in FIG. Pressure was applied. At this time, the upper surface 24a of the glass was pressed and deformed by the pressure sensor 36a installed on the shaft 36 until the pressure reached 5N, and the entire surface was brought into close contact with the suction port surface 34a. The time required for this pressure deformation was 2 seconds.
[0035]
Further, the internal pressure of the suction port by the suction finger is set to 5.00 × 10 ³ The pressure was set to give a low pressure difference corresponding to Pa, the glass 24 was sucked and held, and the shaft 36 was released downward. Further, the cylinder 32 is moved to place the sucked glass 24 on the lower mold member 3 (immediately after the glass 24 is placed on the lower mold member 3 at the end of the suction and transfer), the glass has a viscosity. 10 ⁷ dPa · s.
[0036]
Then, the shaft 35 was returned, and the gate valve 18 was closed. The upper and lower mold members 2, 3 have a glass viscosity of 10 ^8.5 While maintaining the temperature corresponding to dPa · s, the cylinder 37 is driven, and the operation of the shaft 38 causes the upper mold member 2 to move until the lower surface of the flange of the upper mold member 2 completely contacts the upper surface of the body mold 4. Pressure (5000 N) was applied for 60 seconds to mold the glass.
[0037]
With the lower surface of the flange of the upper mold member 2 abutting against the upper surface of the body mold 4, the glass is cooled while being placed in the mold, and as the glass 24 b is cooled and contracted, the lower mold member 3 is cooled. The lower mold cylinder 39 was actuated, and the lower mold 3 was pressed by the tip of the lower mold shaft 40 with a force of 3000 N from below.
[0038]
Glass 24b has a viscosity of 10 ¹⁴ When the temperature reaches dPa · s, the pressurization by the lower die cylinder 39 is stopped, and then the upper die cylinder 37 is immediately moved upward, and the upper die 2 is fixed by the hook 6 fixed to the upper die shaft 38. The mold was opened by hooking the flange.
[0039]
Next, the gate valve 19 was opened, the taken-out cylinder 44 was driven, the suction finger 46 provided at the tip of the take-out shaft 45 was moved onto the lower mold 3, and the obtained precision glass product 24b was sucked. Then, the take-out cylinder 44 is returned, stopped on the table 43, and the drive cylinder 41 of the table is moved to release the suction of the suction finger 46 when the table 43 is brought into the position of touching the lower surface of the glass 24b. . After moving the cylinder 41 downward and placing the product 24b on the cylinder 41, the shaft 45 was further returned to the position shown in FIG.
[0040]
The gate valve 19 was closed, the taken-out chamber lid 17 was opened, and the product 24b was taken out of the taking-out chamber 12 with a hand (not shown).
[0041]
The take-out chamber lid 17 was closed, and the atmosphere in the take-out chamber 12 was replaced by the above operation to prepare for the next take-out. As described above, the molding tact from receiving the molten glass to taking out the glass product was 180 seconds.
[0042]
This molding operation was repeated 100 times, and the quality of the obtained product 24b was confirmed. As a result, no abnormality such as wrinkles due to deformation due to suction and conveyance of the glass gob was observed in the appearance of the product 24b. The surface accuracy was as good as less than one for both ass and habits.
[0043]
At this time, the surfaces of the mold members 1, 2, and 3 and the suction finger 34 were observed. However, no harmful volatiles were found to adhere, and it was still in a state in which continuous molding was sufficiently possible.
[0044]
As a comparison, when the same pressure was applied to the glass gob 24 during the ascending drive of the cylinder 36 and the same pressure was applied to the glass gob 24 after the suction, and the same molding was performed after suction, the appearance of the product 24b was deformed wrinkles (adsorption deformation was large, Inferior products such as broken glass occurred frequently) with a probability of 50% or more. Further, the internal pressure of the transfer / suction port of the suction finger 34 is set to be 1.0 × 10 ⁴ When the glass gob was adsorbed with a high pressure difference of Pa or more, the above-mentioned defective glass appearance products were generated with almost the same probability.
[0045]
Further, the internal pressure of the suction port of the suction finger 34 is set to 1.5 × 10 ² When the pressure difference was lower than Pa and the pressure difference was lower than the external pressure of the suction port, poor suction of glass occurred with a probability of 20% or more.
[0046]
In the above embodiment, when the suction of the glass lump by the suction finger 34 is realized, at the high glass temperature, the upper surface of the glass lump is deformed at the time of suction to be suitable for the next molding, and the suction force is applied. It is necessary to select and set the contact area of the suction finger 34, the area where the suction force acts, and the suction pressure in relation to the weight of the glass lump because it is necessary to avoid deformation that locally causes wrinkles.
[0047]
Therefore, various experiments were attempted. An example is shown in the table below.
[0048]
[Table 1]

Table 1 shows specific numerical values of the weight of the glass material, the contact area of the glass material, and the area of action of the attraction force of the glass material in Example 1 and Examples 2 and 3 described below. I have. Note that the size of the contact area of the glass material is significant only in the deformation of the glass material before adsorption, and the relationship with the suction force is only airtight with external pressure (full-circumference state). There is no problem if is maintained.
[0049]
[Table 2]

In the above table, it is understood that the suction pressure is set by the weight of the glass material / the area of action of the suction force (the suction area of the suction port). In addition, the difference in suction pressure within a range that does not cause deformation such as wrinkles is limited by the relationship with the viscosity of the glass material. In other words, regardless of the type of the glass material, the above-described deformation is related to the glass viscosity and the adsorption pressure difference.
[0050]
In consideration of this point, the suction area of the suction port of the suction finger and the suction pressure must be selected and set (this is also a matter to be considered in the following embodiments).
[0051]
In such an embodiment of the present invention, a glass gob (mass) in a high-temperature softened state is obtained on the receiving mold from the optical glass melted in the melting crucible and flown out, and is brought into contact with the suction surface of the suction section of the suction transfer device. In the case where the optical element is obtained by using a press mold while adsorbing and conveying in a deformed state, the following specific effects are obtained.
[0052]
-A low-viscosity (high temperature, irregular shape) glass gob can be conveyed to a press mold in a short time, and the production cost can be reduced by shortening the molding cycle.
[0053]
-Integrated production of optical elements from molten optical glass by press molding becomes possible, and production costs can be reduced by reducing material costs and molding cycles (no heat energy loss from melting to press molding).
[0054]
-The yield of molded products is improved by preventing deformation due to the adsorption of the glass gob and poor folding at the time of press molding.
[Example 2]
Using the same glass raw material used in Example 1, as shown in FIG. 3, the effective diameter was 13 mm, the product outer diameter was about 17 mm, the center thickness was 3 mm, and the radius of curvature of the optical surface was 20 mm and 30 mm. A molding method for molding a concave meniscus lens will be specifically described with reference to FIGS.
[0055]
As in Example 1, a glass viscosity of 10 ² The molten glass having a temperature corresponding to dPa · s is caused to flow out of the outlet 22 onto the receiving mold 1 (made of carbon-based material and having a concave shape of a sphere R30 mm). After closing, the inside of the molding chamber 11 and the take-out chamber 12 is once evacuated, and then N ₂ The gas was introduced, and the upper and lower heaters 54 and 55 were energized. ^8.5 Heat to a temperature corresponding to dPa · s.
[0056]
The receiving mold 1 has a glass viscosity of 10 as in the first embodiment. ^8.5 It is heated to a temperature corresponding to dPa · s. Then, the outflow glass is received by the receiving mold 1, a predetermined amount of the molten glass lump 24 is taken out, placed in the replacement chamber 10, the lid 14 of the replacement chamber is closed, and the inside of the replacement chamber 10 is N ₂ After the gas replacement, the gate valve 18 was opened, and the suction finger 34 was moved onto the glass block 24. Then, the shaft 36 was driven to rise, and the upper surface 24a of the glass 24 on the receiving mold 1 was brought into contact with the suction finger 34 as shown in FIG.
[0057]
Here, the suction finger 34 is formed in the center of the suction surface 34a in contact with the upper surface 24a of the glass lump, and in a ring shape around the suction surface 34a, a region where a suction force is applied is formed in a center diameter range of 11 mm to 13 mm. The suction port 34b is further provided with a ring-shaped suction surface 34c on the outer periphery of the suction port 34b.
[0058]
At this time, the upper surface 24a of the glass is pressed and deformed by the suction finger 34 by the pressure sensor 36a installed on the shaft 36 until the pressure becomes 15N, and the suction surface 34a and 34c are completely adhered. I let it. The time required for this pressure deformation was 5 seconds.
[0059]
Next, the internal pressure of the suction port of the suction finger is higher than the pressure outside the suction port by 5.00 × 10 5 ³ By applying a suction force with a pressure difference of Pa lower, the glass 24 was sucked and held, and the shaft 36 was released downward. Further, the cylinder 32 was moved, and the sucked glass 24 was placed on the lower mold member 3. At the end of the suction conveyance (immediately after the glass 24 is placed on the lower mold member 3), the glass viscosity is 10 ⁷ dPa · s.
[0060]
Then, the shaft 33 is returned, the gate valve 18 is closed, and the upper and lower mold members 2 and 3 are adjusted to a glass viscosity of 10%. ^8.5 While maintaining the temperature at dPa · s, the cylinder 37 is driven to apply a pressure (4500 N) to the upper mold member 2 via the shaft 38, and the lower surface of the flange of the upper mold member 2 is moved to the upper surface of the body mold 4. The glass is press-molded for an additional 80 seconds until the glass is completely hit.
[0061]
In this state, the lower mold member 39 is operated to cool the glass 24b and follow the lower mold member 3 in accordance with the cooling and shrinkage of the glass 24b. Was pressed from below with a force of 2500 N.
[0062]
Glass 24b has a glass viscosity of 10 ¹⁴ When the temperature reaches dPa · s, the pressurization by the lower mold cylinder 39 is stopped. Then, the upper mold cylinder 37 is immediately moved upward, and the upper mold member is fixed by the hook 6 fixed to the upper mold shaft 38. The mold was opened by hooking the second flange.
[0063]
Next, the glass product 24 b was taken out of the take-out chamber 12 in the same manner as in Example 1. In this case, the molding tact from receiving the molten glass by the receiving mold 1 to taking out the glass product was 210 seconds.
[0064]
This molding operation was continuously repeated in the same manner as in Example 1, and the quality of the obtained product 24b was confirmed. The appearance of the product 24b showed no abnormality such as adsorption of glass gob, deformation during transportation, and wrinkles. It was not recognized, and the surface accuracy was as good as less than one for both ass and habits. Observation of the surface of each of the mold members 1, 2, 3 and the suction finger 34 at the time of continuous use 100 times shows no adhesion of harmful volatiles, and the molding can be continued sufficiently. Condition.
[0065]
Further, in the present embodiment, although the glass product shape was a concave meniscus lens, the same product shape was used for the convex meniscus lens and the biconcave lens, and the same molding was performed in the above-described molding method. The result about the molding of was obtained.
[0066]
In this embodiment, the glass gob (mass) in the softened state at high temperature is deformed into a shape similar to a molded product on the suction surface of the suction portion of the suction transfer device, and then molded using a press molding die. Since the element was obtained, the following specific effects were obtained in that respect.
[0067]
-The shape area of the press-formed product can be enlarged.
[0068]
A low-viscosity (high temperature, irregular shape) glass gob can be transported to a press mold in a short time, and the production cycle can be reduced by shortening the molding cycle.
[0069]
・ Molded optical elements can be integrated from molten optical glass, and the production cost can be reduced by shortening the material cost and molding cycle (no heat energy loss from melting to press molding).
[Example 3]
FIG. 7 schematically shows a cross section of the device for explaining a third embodiment of the present invention. Here, reference numeral 71 denotes a glass block, reference numeral 76 denotes a table for placing the glass block, and reference numeral 74 denotes a replacement chamber provided adjacent to the molding chamber 11 for replacing the glass block 71 from an atmospheric atmosphere to a non-oxidizing atmosphere. . The replacement chamber 74 includes an opening / closing port 75 for communicating the replacement chamber chamber 74a with the atmosphere, and a carry-in cylinder 73 is attached to the chamber 74a. And is inserted into the replacement chamber 74 via the. At the tip of the shaft 72, a suction finger 72a is attached, which sucks the glass block 71 placed in the replacement chamber 74, passes through the gate valve 18, and is provided inside the molding chamber 11. It can be moved on the heating mold 70 which is located. The replacement chamber 74a is provided with an exhaust port (not shown) for evacuation and a supply port for supplying atmospheric gas.
[0070]
The molding chamber 11 is isolated from the outside air by the molding chamber 15, and is adjacent to the replacement chamber 74 and the take-out chamber 12 partitioned by the gate valves 18 and 19. In the chamber 15, a heating type driving cylinder 83, a transfer cylinder 85, and upper and lower mold cylinders 37 and 39 for precision molding are attached on the upper and lower sides. Each of the cylinder shafts 82, 78, 38, 40 is inserted into the molding chamber 11 via seal rubbers 84, 86, 64, 65.
[0071]
A heating mold 70 having a built-in heater 70a is attached to the tip of the cylinder shaft 82. By driving the cylinder 83 upward, the glass block 71 sucked by the suction finger 72a is placed on the heating mold 70. Can be placed. A pressure sensor 82a is attached to an intermediate portion of the cylinder shaft 82.
[0072]
Reference numeral 77 denotes a heating device for heating the glass block 71 conveyed into the molding chamber 11 to a temperature at which press molding can be performed. At the tip of the cylinder shaft 78, a suction finger 79 having a built-in heater 80 is attached, thereby sucking the glass block 71 heated to a temperature at which press molding can be performed on the heating mold 70, and It can be placed on top of.
[0073]
A hook 6 is attached to the tip of the cylinder shaft 38 to lift the upper mold member 2 and open the mold. A body mold 4 is placed between the shafts 38 and 40. The body mold 4 has an upper mold member 2 and a lower mold member 3 formed in a through hole formed by penetrating between upper and lower portions thereof. The inserted upper mold member 2 is configured to be pressurized by the tip of the shaft 38 when pressurized, and to be lifted by hooking a flange provided at an upper portion with the hook 6 when ascending. The lower mold member 3 is supported by a bottom plate 5 and has a structure that can be moved up and down inside the body mold 4. Further, the body mold 4 is provided with an upper mold heater 54 and a lower mold heater 55 for adjusting the temperature of the upper mold member 2 and the lower mold member 3.
[0074]
The take-out chamber 12 includes a take-out chamber 16 and a lid 17 thereof, similarly to the molding chamber 11, and a drive cylinder 41 and a take-out cylinder 44 of a table are attached to the chamber 16. One end sides of the cylinder shafts 42 and 45 of both cylinders 41 and 44 are inserted into the molding chamber 11 via seal rubbers 67 and 68, and a mounting table 43 is attached to a tip of the shaft 42. . A suction finger 46 is attached to the tip of the shaft 45, and the molded product on the lower mold member 3 can be placed on the table 43 by driving the cylinder 44.
[0075]
Further, a seal rubber 66 is attached between the lid 17 and the chamber 16 so that airtightness can be maintained. The molding chamber 15 and the take-out chamber 16 are provided with an exhaust port (not shown) for evacuation and a supply port for supplying atmospheric gas, as in the case of the replacement chamber 13.
[0076]
The molding method of the present invention will be specifically described using the optical element molding apparatus having such a configuration. First, a forming material (blank) for the glass block 71 is prepared. As the glass lump 71, a glass lump having a molten glass flow obtained without generating shear marks and having no defect in appearance is most desirable in terms of cost, but when the production of optical elements is performed in small lots, A processed product that has been ground and polished in advance may be used as the molding material. In this example, the same glass material as in Example 1 was used, and a ground and polished product approximated to the shape of a molded lens was used. As shown in FIG. The case of forming a biconvex lens having a thickness of 4 mm and a radius of curvature of the optical surface of 25 mm or 30 mm will be described below with reference to FIG.
[0077]
At room temperature, a glass block 71 is prepared at a position adjacent to the replacement chamber 74. The opening / closing port 75 of the replacement chamber 74 is opened, and the inside of the replacement chamber 74 is made to be in the atmosphere. The glass block 71 at normal temperature is placed on a glass table 76 in the replacement chamber 74 by using a supply and transfer device (not shown). The suction conveyance device (not shown) retreats to the outside of the replacement chamber 74, the opening and closing port 75 is closed, and the replacement chamber 74 is kept airtight.
[0078]
After replacing the inside of the replacement chamber 74 with a non-oxidizing gas atmosphere (the oxygen concentration in the replacement chamber 74 and the oxygen concentration in the molding chamber 11 are equal), the gate valve 18 is opened. The carry-in cylinder 73 is driven to move the suction finger 72a of the shaft 72 onto the glass lump 71, and the upper surface 71a of the glass lump is sucked by the suction finger 72a. Further, the cylinder 73 is moved, the adsorbed glass block 71 is placed on the heating mold 70 in the molding chamber 11, the shaft 72 is returned, and the gate valve 18 is closed.
[0079]
The room temperature glass block 71 placed on the heating mold 70 is heated to a pressable temperature by a heating device 77 installed above the heating mold 70. The heating device 77 has a structure having a spheroidal reflecting mirror around the halogen lamp, and is capable of condensing infrared light emitted from the halogen lamp onto the glass block 71.
[0080]
In the present embodiment, the heating mold 70 is made of a carbon-based material, and the built-in heater 70a always has a glass viscosity of 10%. ^8.5 It is heated and held at a temperature corresponding to dPa · s. At room temperature, the glass lump 71 placed on the heating mold 70 is heated at a power of 100 W of a halogen lamp of the heating device 77, and after 40 seconds from the start of heating, the glass lump 71 ^7.9 It was heated to a temperature corresponding to dPa · s.
[0081]
Next, the carry-in cylinder 85 was driven to rotate, and the suction finger 79 of the shaft 78 was moved onto the heated glass block 71. The shaft 82 was driven to ascend, and the upper surface 71 a of the glass block 71 on the heating mold 70 was brought into contact with the suction port 79 a of the suction finger 79, and pressure was applied. At this time, the glass upper surface 71a was pressed and deformed by the pressure sensor 82a installed on the shaft 82 until the pressure reached 8N. The time required for this pressure deformation was 3 seconds.
[0082]
Next, the internal pressure of the suction port is set to 1.00 × 10 ⁴ The glass 71 was sucked and held while the pressure difference was low, and the shaft 82 was released downward (at this time, the range of the pressure difference capable of being sucked and held was 5.00 × 10 5 ³ Pa ~ 2.00 × 10 ⁴ Pa).
[0083]
Further, the carry-in cylinder 85 was driven to rotate, and the sucked glass lump 71 was placed on the lower mold member 3. At the end of the suction and conveyance, that is, immediately after the glass block 71 is placed on the lower mold member 3, the glass viscosity is 10 ^8.2 dPa · s.
[0084]
After returning the shaft 78, the glass product 71b was press-molded and opened in the same manner as in Example 1, and then taken out of the take-out chamber 12. The molding conditions at this time were as follows.
[0085]
・ Pressing force of upper mold member 2: 4800N, press deformation time: 70 seconds
・ Pressing force of lower mold member 3: 2800 N (at this time, glass 71b has a viscosity of 10 ¹⁴ (Temperature equivalent to dPa · s)
・ Molding tact from receiving molten glass with receiving mold to taking out molded product: 270 seconds
This molding operation was continuously repeated in the same manner as in Example 1. When the quality of the obtained product 24b was confirmed, the appearance of the product 71b showed no abnormalities such as deformation and wrinkles due to suction and transport of the glass gob. Also, the surface accuracy was as good as less than one for both ass and habits. In addition, at the time of 100 continuous uses, no harmful volatiles were found to adhere to the surface of the suction surface of each of the mold members 1, 2, 3 and the suction finger 79. Met.
[0086]
In this embodiment, the glass viscosity is always 10%. ^8.5 The normal temperature glass lump 71 placed on the heating mold 70 heated and held at a temperature corresponding to dPa · s is heated to a glass viscosity of 30 W after the start of heating at a halogen lamp output of the heating device 77 of 100 W. Ten ^8.2 It was heated to a temperature corresponding to dPa · s.
[0087]
Next, the carry-in cylinder 85 was driven to rotate, and the suction finger 9 of the shaft 78 was moved onto the heated glass block 71. The shaft 82 was driven to ascend, and the upper surface 71 a of the glass block 71 on the heating mold 70 was brought into contact with the suction port 79 a of the suction finger 79, and pressure was applied. At this time, the glass upper surface 71a was pressed and deformed by the pressure sensor 82a installed on the shaft 82 until the pressure reached 10N. The time required for this pressure deformation was 5 seconds.
[0088]
Next, the internal pressure of the suction port by the suction finger 79 is increased by 4.00 × 10 4 from the external pressure of the suction port. ⁴ The glass 71 was sucked and held while the pressure difference was low, and the shaft 82 was released downward (the range of the pressure difference that could be sucked and held was 1.00 × 10 ⁴ Pa-5.00 x 10 ⁴ Pa is set).
[0089]
Further, the carry-in cylinder 85 was driven to rotate, and the sucked glass lump 71 was placed on the lower molding die 3. At the end of the suction and conveyance, that is, immediately after the glass block 71 is placed on the lower mold member 3, the glass viscosity is 10 ^8.5 dPa · s.
[0090]
In the present embodiment, a predetermined amount of optical glass lump is heated and softened by using a heating device, and the glass lump in a high temperature softened state obtained by this is brought into contact with the suction surface of the transport unit and sucked in a deformed state. The optical element is obtained using a press mold, and at this time, the following specific effects are obtained.
[0091]
-The glass gob (mass) in a softened state at a high temperature can be transported to a press mold in a reliable and short time, and the production cycle can be reduced by shortening the molding cycle.
[0092]
-Reheating time for softening on the press mold is not required, and the production cost can be reduced by shortening the molding cycle.
[0093]
【The invention's effect】
The present invention, as described above, adsorbs a glass lump in a high-temperature softened state to a suction portion of a suction / transport device, transports the glass lump to a molding die including a pair of upper and lower mold members, and loads a glass lump between the mold members. In the method of molding an optical element, press molding is performed, wherein a glass lump in a high-temperature softened state having an irregular shape is brought into contact with the suction surface of the suction section and deformed to form a glass lump having a constant shape corresponding to the suction surface. The glass block is attracted to the suction portion by a suction force that does not deform the surface of the glass block on which the suction force acts, and is conveyed to a molding die.
[0094]
In this case, the glass mass in the high-temperature softened state flows out of the optical glass melted in the melting crucible from the nozzle and is received in a receiving mold, and is a predetermined amount of the obtained glass mass in the high-temperature softened state, or It is preferable that the glass lump in the high temperature softened state is a glass lump in a high temperature softened state obtained by heating and softening a predetermined amount of optical glass lump received in a receiving mold using a heating device.
[0095]
In the present invention, the viscosity of the glass lump in the high-temperature softened state is 10 when the adsorption starts. ⁵ dpa · s or more 10 ⁸ dpa · s or less, and the adsorbing force of the adsorbing section is such that the pressure difference from the outside is 1.00 × 10 ² Pa or more 5.00 × 10 ⁴ Pa or less, and the adsorption surface has an area corresponding to the weight of the glass block at that time.
[0096]
In this case, at the time when the suction accompanying the transfer by the suction transfer device ends, the viscosity of the glass lump becomes 10%. ⁶ -10 ⁹ It is desirable to be in the range of dpa · s. Further, it is preferable that the suction surface has a shape adapted to deform a glass lump in a high-temperature softened state into a shape similar to a molded product at the time of molding.
[0097]
Accordingly, in the present invention, when the glass gob is transported from the first glass gob receiving mold to the second press mold, and the press molding is performed, the glass lump still in a high-temperature softened state has a low viscosity (temperature). The glass gob can be loaded into the mold in a viscous state in which it can be molded by being reliably adsorbed as it is and the shape is not fixed) and conveyed to the second press mold in a short time. An excellent effect that high efficiency production can be realized is obtained.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a configuration of a molding apparatus used in a method for molding an optical element according to first and second embodiments of the present invention.
FIG. 2 is a cross-sectional view showing an example of a precision glass product formed by the method for forming an optical element according to the first and third embodiments of the present invention.
FIG. 3 is a cross-sectional view illustrating an example of a precision glass product formed by a method for forming an optical element according to a second embodiment of the present invention.
FIG. 4 is a cross-sectional view showing an example of a state in which a glass lump in a high-temperature softened state is adsorbed in the method for molding an optical element according to the first embodiment of the present invention.
FIG. 5 is a cross-sectional view showing an example of a state in which a glass lump in a high-temperature softened state is adsorbed in a method for molding an optical element according to a second embodiment of the present invention.
FIG. 6 is an explanatory view showing a part of the molding step in the method for molding an optical element according to the first embodiment of the present invention.
FIG. 7 is a schematic sectional view showing a configuration of a molding apparatus used in a method for molding an optical element according to a third embodiment of the present invention.
[Explanation of symbols]
1 receiving mold
2 Upper mold member
3 Lower mold member
4 body type
5 Bottom plate
6 hooks
10,74 replacement room
11 Molding room
12 take-out room
13,74a Replacement chamber
14 Replacement chamber lid
15 Molding chamber
16 Extraction chamber
17 Removal room lid
18, 19 Gate valve
20 melting furnace
21 Outflow pipe
22 Outlet
23 molten glass
24,71 molten glass lump
24a Top surface of molten glass block
24b Precision glass products
32 Loading cylinder
33 Loading cylinder shaft
34,79 Suction finger
34a Suction finger suction surface
34b, c Suction finger suction port
35 receiving type drive cylinder
36 receiving type drive cylinder shaft
36a Receiving pressure sensor
37 Upper cylinder
38 Upper cylinder shaft
39 Lower cylinder
40 Lower cylinder shaft
41 Cylinder drive cylinder
42 Mounting table drive cylinder shaft
43 table
44 Take-out cylinder
45 Take-out cylinder shaft
46 Suction finger
51 Receiving heater
52,80 Suction finger heater
53 Replacement room heater
54 Upper heater
55 Lower heater
61-68,81,84,86 Seal rubber
70 heating type
72 Loading cylinder shaft
73 Loading cylinder
75 opening
76 Glass mounting table
77 heating device
78 Suction finger shaft
85 Suction finger cylinder

Claims (6)

A method for molding an optical element, in which a glass lump in a high-temperature softened state is adsorbed to a suction portion of a suction / conveyance device, and is conveyed to a molding die composed of a pair of upper and lower mold members. At
The glass lump in a high-temperature softened state whose shape is not constant is brought into contact with the suction surface of the suction portion and deformed to form a uniform shape corresponding to the suction surface in the glass lump, and the glass lump acting on the suction force. A method for adsorbing the glass block to an adsorbing section with a suction force that does not deform the surface of the glass element, and transporting the glass lump to a molding die. The glass mass in the high-temperature softened state, wherein the optical glass melted inside the melting crucible flows out of the nozzle, is received in a receiving mold, and is obtained as a predetermined amount of the glass mass in the high-temperature softened state. 2. The method for molding an optical element according to 1. The glass mass in the high temperature softened state is a glass mass in a high temperature softened state obtained by heating and softening a predetermined amount of optical glass mass received in a receiving mold using a heating device. 2. The method for molding an optical element according to 1. The glass mass in the high-temperature softened state has a viscosity of not less than 10 ⁵ dpa · s and not more than 10 ⁸ dpa · s at the time of starting the adsorption, and the adsorbing force of the adsorbing portion has a pressure difference with the outside. The range of 1.00 * 10 < ² > Pa or more and 5.00 * 10 < ⁴ > Pa or less, and the said adsorption | suction surface hold | maintains the area commensurate with the weight of the glass lump at that time, The claim 1 characterized by the above-mentioned. A method for molding the optical glass according to the above. The method of molding an optical element according to claim 4, wherein the viscosity of the glass lump is in the range of 10 < ⁶ > to 10 < ⁹ > dpa.s at the time when the suction accompanying the transfer by the suction transfer device is completed. The method according to claim 1, wherein the suction surface has a shape adapted to deform a glass lump in a high-temperature softened state into a shape approximating a molded product at the time of molding. .

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